March 2009 - iThemba LABS

Transcription

iThemba LABS Annual Report 2009
iThemba LABS
Annual Report
March 2009
This report covers the period
1 April 2008 to 31 March 2009
Some of the results presented in this report
are in part preliminary and should not be
quoted without the approval of the authors
Editor: Kobus Lawrie
Assistant Editor: Elza Hudson
Cover: Herman Du Plessis
Published in 2009
iThemba LABS
P O Box 722
Somerset West
7129
South Africa
Design and Layout by iThemba LABS
Printed in the Republic of South Africa
by iThemba LABS, Faure
Copyright of this report is the property of the
 National Research Foundation
1
Members of the Director’s Council
Dr Trevor Mdaka
Chairman
Professor David Aschman
University of Cape Town
Professor Joao Rodrigues
University of the Witwatersrand
Professor Mike Sathekge
University of Pretoria
Professor Frederik Scholtz
University of Stellenbosch
Professor Fred Vernimmen
University of Stellenbosch
iThemba LABS
Telephone: International +27-21-843-1000
National: 021-843-1000
Fax: International +27-21-843-3525
National: 021-843-3525
e-mail: [email protected]
worldwide web: http://www.tlabs.ac.za
2
FOREWORD:
FOREWORD
The
year
2008/09
was
by
many
accounts
characterised by major milestones and great
achievements. It has to be noted that this was against
the backdrop of a less than propitious financial climate
as well as power outages, which hampered most of
our activities. However, I am pleased to note that in
spite of these and many other challenges, we have
been able to make headway on many tasks we set out
to achieve.
iThemba LABS celebrated the twentieth anniversary of
the Separate Sector Cyclotron (SSC) in November
2008,
with
a
two-day
symposium
Achievements and Future Plans.
on
Past
This event
highlighted the vital role that iThemba LABS plays
within the National System of Innovation as well as
First test beams are expected before the end of the
within the International Nuclear Science Landscape, in
year. Eagerly awaited will be the first Lithium beams
actively promoting Human Capital Development,
which – it is hoped – could be delivered early next
Technological Innovation and world-class research
year.
and its applications.
Construction of the beam splitting facility for more
We have had more local and international users than
frequent production of 18F-FDG is nearing completion.
ever before applying for beam-time for their research
Demand for long-lived radionuclides in the export
programmes carried out at the SSC. Four of the six
market remains buoyant and there is now an urgent
reviewers for the five-year research plans have
need to increase production capacity to meet the
responded. One key salient point that could be picked
projected higher off-take from May / June 2009
up from the physics review is a suggestion of looking
onwards. Capital equipment is required for a beam
at the feasibility of establishing a radioactive isotope
splitter which will result in the simultaneous
beam facility (RIB).
bombardment of two target stations compared to only
one currently in operation. The development of the
Beam uptime on the SSC on a year-to-date basis
beam splitter has been initiated in-house and
averaged 63%. The commissioning of the Berlin-ECR
installation and commissioning will be finalised in the
Ion Sources has commenced, following the electrical
new financial year.
upgrade project which was completed in May 2008.
3
The Van de Graaff beam availability improved to
competing demands for beam times from isotope
67,4% (~53% last year) with usage at 36,4% (~27%
production and nuclear physics research.
last year). Maintenance was 10% below the previous
year.
The
Following a Memorandum of Understanding
RSA/CERN
Program,
an
international
collaboration between the European Centre for
between iThemba LABS and the Centre for Energy
Nuclear Research (CERN), South African Universities
Research and Development (CERD) in Nigeria,
and iThemba LABS, was officially launched in
signed in May 2007 for the design and construction of
December 2008 although formal research visits to
an end-station for Ion Beam Analysis on Nigeria‟s new
CERN had commenced in March 2008.
1,7 MV Tandem Accelerator, a team from iThemba
Interim
funding of R3,3m for 2008/09 was provided by the
LABS guided this project to its successful completion
DST.
in April 2008. CERD will utilise the new facility for
The collaboration seeks to actively provide research
studies in biomedical and materials sciences. The
platforms for both South African scientists and
end-station consists of a scattering chamber which
students at CERN. The launch of the Large Hadron
can be used for multiple techniques using broad ion
Collider (LHC) at CERN in September 2008 generated
beams of varying diameter, and detectors for X-Ray,
tremendous interest in South Africa and the local
gamma-ray and backscattered particle detection.
programme seeks to take full advantage of the latest
A steady stream of neutron therapy patients can be
accelerator technologies offered at CERN. The South
reported. This year we have seen a marked increase
African Universities involved are Cape Town,
in foreign patients seeking therapy at our facilities.
KwaZulu-Natal, Johannesburg, Witwatersrand and
This came about as a result of an agreement – in the
Rhodes.
form of a Memorandum of Understanding – signed
A dramatic increase in joint lectures / seminars and
between iThemba LABS and Essen University, to
student / scholar outreach activities can be noted, as
facilitate treatment for patients requiring neutron
exemplified by the record number (11 000) of total
boosts. To date three German patients have been
visitors during 2008/09. These efforts greatly enhance
treated for unique conditions requiring neutron therapy
our visibility and thus help fulfil the mandate of
and two more patients are in the pipeline. These are
iThemba LABS‟ status as a national facility.
indeed very positive developments and we have
received glowing reports from the German clinician
The work described in this report reflects not only the
who conducted all the referrals.
efforts of iThemba LABS‟ staff members, but also of
many users and collaborators. We are, indeed, very
However, on the proton therapy side, the picture has
grateful for their contributions as well as to many of
been less than sanguine. This is largely due to the
our advisers, committee members and suppliers.
fact that the new beam schedule imposed highly
Only three
Z Z Vilakazi
patients, mostly requiring stereotactic radio-surgery,
DIRECTOR
restrictive constraints on fractionation.
have been treated to date. Plans are in place to
review the current schedule in view of these dwindling
numbers; however, these plans should factor in other
4
Contents
1.
GROUP OPERATIONAL HIGHLIGHTS.........................................................................................6
1.1
Accelerator Group ......................................................................................................................................... 7
1.2
Medical Radiation Group ............................................................................................................................ 17
1.3
Radionuclide Production ............................................................................................................................. 23
1.4
Materials Research Group ........................................................................................................................... 31
1.5
Physics Group ............................................................................................................................................. 34
1.6
iThemba LABS (Gauteng)............................................................................................................................. 37
1.7
Electronics and Information Technology ..................................................................................................... 41
1.8
Safety, Health and Environmental Management ......................................................................................... 45
1.9
Science and Technology Awareness Programme ......................................................................................... 54
2.
SCIENTIFIC AND TECHNICAL REPORTS................................................................................. 55
2.1
Medical Radiation Group ............................................................................................................................ 56
2.2
Radionuclide Production ............................................................................................................................. 67
2.3
Physics Group ............................................................................................................................................. 81
2.4
Radiation Biophysics Group ........................................................................................................................ 94
2.5
Materials Research Group ......................................................................................................................... 117
2.6
iThemba LABS (Gauteng)........................................................................................................................... 149
3.
PERFORMANCE SUMMARY ..................................................................................................... 153
3.1
Directorate Level Organisation ................................................................................................................. 154
3.2
Financial Performance .............................................................................................................................. 155
3.3
Internal Key Performance Indicators (KPI’s) .............................................................................................. 157
3.4
Human Resources ..................................................................................................................................... 158
4.
APPENDICES ................................................................................................................................ 161
5
1. GROUP OPERATIONAL HIGHLIGHTS
6
Accelerator Group
1.1 Accelerator Group
1.1.1 Overview
Apart from the day-to-day operational activities of supplying the required beams to the various users at the
facility, the accelerator group is also continuously involved in projects to increase the availability and quality of
beam delivery to the users. These projects include the beam splitter system, non-destructive beam position and
profile measurement systems, ECR ion sources and a multi-probe phase measurement system for the SSC. A
new ion source for the Accelerator Mass Spectrometry (AMS) development at iThemba LABS (Gauteng) also
became a reality owing to a financial grant from the International Atomic Energy Agency (IAEA). A second grant
of R4,4m has also been approved for AMS under the National Equipment Programme (NEP), which is
administered by the National Research Foundation (NRF).
Although no forced load shedding was experienced since April 2008, voluntary load shedding had a negative
impact on the availability of beam during 2008 and therefore the accelerator performance (beam supplied 75,17%
of scheduled beam time) was approximately 4% lower than the previous year.
1.1.2 Beam Splitter
A major achievement this year was the completion of the installation of the beam splitter system during the long
shutdown period that started in December 2008. The Electronics and Information Technology (EIT), Technical
Support Services (TSS) and Accelerator groups worked together closely to complete the installation in the allotted
time with no major hold-ups. The beam splitter system will allow the irradiation of targets in two vaults
simultaneously by splitting the beam into two separate beams. An electrostatic channel, operated at 100 kV
across a gap of 34 mm, will be used to peel off a portion of the beam. A magnetic channel further along the
beam line will intercept the peeled-off portion and deflect the beam by 16° into a new beam line.
Figure 1: Electrostatic channel with magnetic channel
in the background
Figure 2: Rotator quadrupole magnets on the isotope
beam line
Beam extracted from the SSC at iThemba LABS is more stable in the vertical direction than in the horizontal
direction. Five quadrupole magnets are used to rotate the beam through 90°, thereby transposing the instability
to the vertical direction. This method will produce more stable beam currents of the two separated beams, as
7
Accelerator Group
well as reduce losses on the septum of the electrostatic channel. The electrostatic channel will need further HV
conditioning before the first tests can be performed to split the beam.
1.1.3 Non-destructive Beam Diagnostics
During preceding years an increase in the current of the 66 MeV proton beam from 100 A to 300 A was
achieved. For safe transportation of these high-current beams, non-destructive beam diagnostic capabilities have
become essential.
Capacitive Beam Position Monitor (BPM)
Non-destructive BPMs have been used successfully at iThemba LABS for a number of years. Due to noise and
RF pick-up, BPMs in the high-energy beam lines are only useful for beam currents of 300 nA and higher. For
proton therapy (using the scattering method) beam position measurements for beam currents as low as 20 nA are
required. A new and more sensitive BPM, as well as electronic measuring equipment, have been developed,
installed and tested in the proton therapy beam line. Initial results are very promising and measurements at
beam currents as low as 10 nA for 200 MeV protons were possible. The project is undertaken in collaboration
with the Forschungszentrum Jülich, Germany.
Beam-induced Fluorescence BPM
A beam-induced fluorescence monitor (32 channel linear array multi-anode photomultiplier tube (PMT)) was used
to measure the profile and position of a 420 A, 3.14 MeV proton beam in the transfer beam line between SPC1
and the SSC. Existing diagnostic equipment in close proximity to the PMT was used to verify the results.
Figure 3 shows that there is a good correlation between the beam profiles measured with the PMT, and a
stepped slit method in conjunction with a Faraday cup. The difference in width is mainly due to the divergence of
the beam over the distance between the two apparatus. This project is also undertaken in collaboration with the
Forschungszentrum Jülich, Germany.
15
1
At slit position
With PMT
Beam position (mm)
Normalised current
0.8
0.6
0.4
-5
Profile grid
5
0
-4
-3
-2
-1
0
1
2
3
4
5
-10
0
-10
BPM
-5
0.2
-15
10
PMT
0
5
10
15
Steering magnet current (A)
Position (mm)
Figure 4: Beam position
Figure 3: Beam profile
Figure 4 shows the beam position measured by means of three different methods. An artificial offset was
implemented for the traces of the BPM (+2 mm) and profile grid (-2 mm) to visually separate the traces on the
graph.
8
Accelerator Group
1.1.4 Electron Cyclotron Resonance (ECR) Ion Sources
Grenoble Test Source
All components of the Grenoble Test Source were delivered to iThemba LABS
during the course of 2008. A temporary room was constructed in the assembly
area of the workshop where the source is being assembled. Two microwave
amplifiers (14 GHz and 18 GHz respectively) were also delivered. Due to financial
constraints, all further development work on the source has been put on hold for
the immediate future.
Figure 5: Grenoble Test Source
being assembled
Hahn-Meitner Source
GANIL originally built this ECR source, with its beam line, for the Hahn-Meitner Institute (HMI). It has been
donated to iThemba LABS and was installed in the ECR vault and linked up to the Q-line. During the past year
the infrastructure of the ion source was also improved by adding a control room and moving some electronic
components into the control room. Before the HMI ECR source and the existing ECR source can be operated
simultaneously, a safety interlock system must still be implemented. To produce the first plasma, 14.5 GHz
microwave power was injected into the source under local control. Ions could be extracted from the source and
1 mA was measured on the first pair of beam line slits. First beam experiments are scheduled for May 2009.
1.1.5 Phase Probes for the Separated Sector Cyclotron (SSC)
A fixed, multi-probe beam phase measurement system
is proposed for the SSC.
The assembly will be
installed in place of the moveable Multi-head Probe 1
in the south valley vacuum chamber.
A total of
20 phase probes will be placed radially in the
accelerator to allow instant and continual beam phase
Figure 6: Phase probe proposal for the SSC
measurement from the innermost to the outermost
orbits, i.e. throughout the acceleration process.
Each phase probe will consist of an upper and a lower capacitive pick-up plate. As part of the complete assembly
the pick-up plates will be shielded individually, as well as collectively, above and below the median plane.
Adequate shielding must be provided to reduce the susceptibility to RF pick-up on the capacitive pick-up plates
and thereby increase the sensitivity of the system as a whole.
The unit is also designed to allow for retraction of the complete assembly from the vacuum chamber on a railand-trolley type system. A coaxial cable will connect to each pick-up plate by means of a vacuum feedthrough
flange close to the pick-up plate. All the coaxial cables will run, in atmosphere, along a welded pipe section to an
interconnecting flange on the wall of the vacuum chamber.
9
Accelerator Group
1.1.6 Accelerator Mass Spectrometry (AMS) at iThemba LABS (Gauteng)
A financial grant from the IAEA made it possible to acquire a multisample (64) Cesium sputter ion source specifically developed for
AMS by the Centre for Accelerator Mass Spectrometry (CAMS)
based at the Lawrence Livermore National Laboratory (LLNL) in the
United States of America. Design drawings were made available to
iThemba LABS under special permission from CAMS.
WITS
Commercial Enterprise (Pty) Limited was awarded a contract by the
IAEA to manufacture the AMS ion source for iThemba LABS
(Gauteng).
The IAEA grant also makes provision to procure vacuum equipment,
power supplies, control modules and some beam line components
for the ion source.
Figure 7: Partially assembled AMS ion
source
A detail specification of the aforementioned was compiled and submitted to the IAEA, who in turn issued
purchase orders to international companies to supply the items, of which 50% have already been delivered to
iThemba LABS to date. The ion source will be commissioned during the course of 2009.
1.1.7 Consultations
Through ongoing collaborations with the Forschungszentrum Jülich, iThemba LABS also became involved in the
design of a magnet system that is required by the Gesellschaft für Schwerionenforschung (GSI), Darmstadt, for a
specific beam diagnostic system to be used as part of the Facility for Antiproton and Ion Research (FAIR) project.
iThemba LABS is in a continuous process of advising GSI on the design and is, to some extent, also involved in
the actual design of the magnets.
1.1.8 Cyclotron Beam Statistics
Cyclotron performance over the past 14 years is shown in Table 1 below. The beam-on-target time declined by
approximately 4% compared to the previous year. The main contributing factor was the national energy crisis.
Interruptions were mainly due to a programme of voluntary load shedding that was introduced as part of a
national energy saving initiative. Other major contributing causes can be ascribed to Radio Frequency (RF)
interruptions and water leaks as a result of ageing equipment, as well as the extended shutdown and service
periods associated with the installation of the beam splitter line.
10
Accelerator Group
Year
Beam Supplied as:
% of Scheduled beam time for:
% of Total time
% of Scheduled* time
Energy Changes
Interruptions
1995
72.95
82.91
5.67
8.46
1996
69.69
78.21
9.30
8.92
1997
67.63
77.31
11.02
10.60
1998
66.93
75.55
13.20
9.73
1999
69.12
78.82
9.99
10.81
2000
58.51
73.07
9.36
15.50
2001
66.13
78.70
6.30
12.61
2002
72.29
82.69
7.50
7.28
2003
70.93
82.79
6.87
8.08
2004
72.0
84.9
6.7
5.9
2005
71.3
83.6
5.5
6.4
2006
66.1
80.3
5.5
7.9
2007
67.1
79.28
5.4
10.4
2008
62.0
75.17
4.0
14.3
* Scheduled time is total calendar time minus scheduled maintenance time and minus the time that the laboratory
is officially closed during December
Table 1: Cyclotron beam delivery statistics for the period 1995 to 2008.
1.1.9 Van de Graaff Accelerator
New Chiller Plant
A chiller for de-ionized water has been completed and is controlling the cooling water to a tolerance of 2°C, which
is better than expected.
New Terminal Potential Stabilizer system
A new National Electrostatic Corporation (NEC) Terminal Potential Stabilizer system was installed to replace the
original 40-year old corona control unit. The Terminal Potential Stabilizer uses two modes of operation, i.e. slit
control or generating voltmeter control, to control the beam energy. The advantage of this control system is that
the control will automatically revert to generating voltmeter whenever the slits malfunction. The system also
incorporates capacitive pick-off monitoring for correction of fast energy fluctuations. The Terminal Potential
Stabilizer system has greatly improved the beam stability and delivers very good energy control of the Van de
Graaff accelerator.
Figure 8: Terminal Potential Stabilizer system
Figure 9: Chiller Plant
11
Accelerator Group
Beam Diagnostics
A new Faraday cup current measurement system was installed with the advantage that all Faraday cups are now
monitored by making use of only one Keithley current meter. This system utilizes an Agilent multiplexer to do the
channel selection and is fully computer controllable.
The Beam Profile Monitors upgrading project is nearing completion and would be a very useful tool, because for
the first time ever it would be possible to overlay multiple profiles so that the deviation of the beam from the
centre line can be observed easily. The system is also fully computerized and will digitize beam profiles for
analysis on a computer screen.
The computerization of the controls for the equipment in the terminal of the Van de Graaff accelerator should be
completed in the coming year. Once this has been done the whole Van de Graaff and its associated equipment
can be controlled remotely via the campus Control Network.
Beam Statistics
Year
Beam on Target
(Hours)
2000
4016
2001
3381
2002
3560
2003
1635
2004
4700
2005
4527
2006
6404
2007
5794
2008
4975
* No records available
Maintenance/Conditioning
(Hours)
2457
497
3212
2331
2329
2360
1457
1591
1072
Development
(Hours)
N/A*
N/A*
N/A*
88
38
1886
776
554
352
Interruptions
(Hours)
N/A*
N/A*
N/A*
N/A*
403
159
164
408
514
Table 2: Van de Graaff beam delivery statistics for the period 2000 to 2008.
1.1.10 Technical Support Services (TSS) Group
Introduction
The TSS group comprises a Mechanical Engineering Division (mechanical workshop and design office) and a
Site Services Division (building and ground maintenance). The group provides a technical support service to
ensure that the core functions of iThemba LABS can be maintained with minimal disruptions. This entails the
maintenance of the complete infrastructure, as well as upgrades and additions to any of the support systems as
required from time to time.
A number of larger projects were completed during the reporting period. These include the beam splitter line,
uninterruptible power supply (UPS) battery upgrade and the upgrade of the electrical distribution system to add
the additional capacity required for the new ion sources and associated equipment.
Apart from the
aforementioned, the general maintenance and repair work was diligently performed throughout the year to
achieve excellent accelerator operational statistics.
12
Accelerator Group
All members of the TSS group endeavour to provide a high quality, cost effective, and reliable service to ensure
that iThemba LABS provides a safe working environment, free of hazards and risks, to all end users at the facility.
Electrical Distribution
No incidences of unplanned load shedding were experienced during the reporting period. iThemba LABS is still
committed to sustain the reduced power consumption levels as per agreement with Eskom. This agreement
constitutes a saving of 10% on the base-line usage of approximately 2.5 million kWh per month. As a result of
power saving initiatives implemented early in 2008, an average saving of 13,7% was achieved during the last
nine months of 2008, which is more than the agreed percentage.

Upgrade of Electrical Infrastructure
The electrical infrastructure upgrade of 1600 kVA was successfully completed and commissioned. The increase
in the Notified Maximum Demand from 5 MVA to 7.5 MVA was approved by Eskom, but due to budgetary
constraints, the payment of the Up-front Distribution Standard Connection Charge (R1,5m) will be delayed until
further notice.

UPS Upgrade
During July 2008 the UPS 1 motor / generator set was returned from Germany after undergoing repairs and reinstalled in the UPS building.
Full replacement of all battery banks of the UPS was completed during September 2008. Re-commissioning of
the UPS units was successfully completed on 19 September 2008. Faulty thyristors had to be replaced on units
1 and 4 during the commissioning phase.
The UPS has been functioning very reliably since re-commissioning. The operating parameters of the UPS are
being monitored and recorded diligently on a daily basis to ensure reliable operation and early detection of
imminent failures.

Electrical Training and Development
Two female electrical apprentices have completed their training and have also completed a final electrical
qualifying trade test during February 2009.
Mechanical Engineering
The Mechanical Engineering division continues to provide a mechanical design, manufacturing, procurement,
assembly and installation service to most divisions and groups within the iThemba LABS structure. Some of the
major projects are discussed below. Staff members also regularly assist members of the operational divisions
with removal / installation and repair of accelerator- and/or beam line components during emergency
breakdowns.

Hot Cell Upgrade
The engineering division designed, fabricated and installed new sample and production hot cells in the isotope
production area. The protective lead shielding for the new clean room hot cells has been designed and is
currently being manufactured in-house. The expected completion date is March 2009.
13

Accelerator Group
Beam Splitter Line
The electrostatic channel and magnetic channel were manufactured,
tested and assembled in the general assembly area.
Final
installation in the isotope production beam line was completed during
the maintenance shutdown period from 12 December 2008 to
23 January 2009. A mechanical hoist system for removing the
septum of the electrostatic channel was also designed,
manufactured and installed above the beam line. Various magnets,
beam pipes, support stands and services were also successfully
Figure 10: Partially assembled electrostatic channel
installed during the shutdown period.

Septum Magnet 2 (SPM2)
Because of the ageing condition of the current SPM2 replacement
components, a complete spare SPM2 had to be manufactured to
permit easy and quick replacement during breakdowns. Due to
financial constraints and to save costs, 70% of the mechanical parts
were manufactured in-house.
Manufacturing of some larger
components was however outsourced.
A new magnet coil was
designed and manufactured in-house. Once the new SPM2 is in
service, the current SPM2 will also be rebuilt with a new magnet coil.
Figure 11: New SPM2 coil assembled into the
magnet
A third coil will be manufactured and stored as an emergency replacement component.

Magnet Coil Manufacturing
A dedicated magnet coil manufacturing facility has been established on site. Here artisans are being trained in
various aspects of coil manufacturing. Magnet coils that have already been manufactured include the following:
magnetic channel, SPM2, steerer magnets and quadrupole magnets. Water cooled coils are manufactured from
copper tubing and steerer coils are wire wound.
Figure 12: Manufacturing of wire-wound steerer magnets
Figure 13: Manufacturing of water-cooled quadrupole magnets
14

Accelerator Group
Mechanical Training and Development
The mechanical engineering division regularly provides training to apprentices and mechanical engineering
trainees. At any given time there are normally two apprentices and two trainees receiving training in the
mechanical workshop. Training provided to trainees is in line with the guideline document for experiential
learning from the Cape Peninsula University of Technology (CPUT). Apprentices follow the Manufacturing,
Engineering and related Services SETA (MERSETA) modules and the training falls within the prescribed
guidelines as set by MERSETA.
All staff members also attend regular training and skills development courses in the areas of CAD software,
pneumatics, specialist welding, overhead crane and forklift operation, occupational health and safety, radiation
protection and computer literacy.
Site Services
The Site Services section is not only responsible for the maintenance and upkeep of the buildings and grounds,
but also provides essential services to the operational and user groups within the iThemba LABS structure.
These services include the electrical distribution, heating, cooling and air conditioning, compressed air and
cooling water. Routine building maintenance and new installations are carried out on a daily basis and a
dedicated team of groundsmen maintains the general appearance of the site and surrounding lawns and gardens.
Some of the major projects are listed below.

UPS Room
Site Services staff assisted with the replacement of the UPS battery banks. The floors in the UPS building were
also cleaned and painted with a durable epoxy coating. The painted floors are easy to clean and enhance the
appearance of the whole area.

Air Handling Unit
Site Services staff assisted an external contractor with the replacement of the controllers for the air handling unit
servicing the red, blue and basement areas of D-block. The complete air handling control and monitoring system
will be upgraded to ensure proper alarms are generated when air flow to and from the various areas are not
within the prescribed limits, i.e. low flow, wrong direction, etc. Alarms are important for warning personnel to
leave the areas immediately in the event of a malfunction of the system.

Stainless Steel Cabinets
New stainless steel cabinets were installed in the D-block clean rooms. Site services was responsible for the
outsourcing of the manufacture and installation of the cabinets, the provision of new plumbing works, lighting and
power outlet points, as well as outsourcing / supervising the completion of the epoxy floor coating.
15
Accelerator Group
Figure 14: Stainless Steel Cabinets

Figure 15: Chiller Room
Chiller Room
During the year-end shutdown it was discovered that the drive-end bearing of the motor on Chiller No 2 had
collapsed, resulting in an oil and gas leak. A highly skilled team from Site Services assisted contractors to
remove the affected parts and to have them repaired and re-installed. The chiller was commissioned successfully
before the end of the shutdown and could be put back in service before accelerator start-up.

Fire Alarm Panels
The fire alarm panels had to be replaced since the installed panels were no longer functional and could not retain
memory status to record alarms. The first phase has been completed and all relevant staff members have
completed in-house training on the use of the new panels.
16
Medical Radiation Group
1.2 Medical Radiation Group
1.2.1 Highlights 2008/2009
Following a workshop on the Future of Proton Therapy that took place at iThemba LABS in November 2007,
Dr Vic Levin from the Clinical Working Group was commissioned to write a report on the actual statistics relevant
to this modality of radiotherapy in South Africa. He submitted his report in April 2008. The report concluded that
an estimated total of 200 state patients would benefit from proton therapy annually, of which almost half would be
paediatric. The report did not consider the referral of private or international patients.
In November 2008, iThemba LABS hosted a two-day symposium to celebrate the twentieth anniversary of
cyclotron operations and the start of patient treatment with neutrons. Invited guests gave first-hand accounts of
the pioneering days of particle therapy in South Africa.
As a result of electricity distribution problems faced by Eskom during 2008, the iThemba LABS management
agreed to implement a voluntary load-shedding scheme whereby a radical change in scheduling for proton
therapy treatments was introduced. This impacted on the Group‟s capabilities to provide continuous service to
our stakeholders. Three patients were treated on the 200 MeV horizontal beam proton therapy facility during the
year.
In 2008, a collaboration between iThemba LABS and the University Duisburg Essen (Faculty of Medicine) and the
University Hospital Essen was started. The aim of this collaboration is to treat patients from Germany at iThemba
LABS using neutrons, and to actively promote joint research in particle therapy. Of the 65 patients treated on the
neutron therapy unit, eight were from Germany.
The following projects related to proton therapy yielded good results:
Chair Control and SPG Systems
The new control system for the treatment chair and collimator was successfully commissioned along with the
modified stereophotogrammetric (SPG) system. The improved lens distortion model was not included in the SPG
system, due to unaddressed implementation issues. However, with the improved outlier detection and singularvalue decomposition calculations, together with the new chair control system, the commissioned system positions
patients considerably faster, as it requires fewer iterations. Also, the positioning accuracy of the system has been
improved, and the variability in the treatment positions has been reduced.
Robotic Patient Positioning System
The integration of the SPG system and robot control system was completed, and a number of software errors in
the initial implementation of the robot path planner were identified and fixed. The robot control system, together
with the SPG system, is now capable of locating the patient in the treatment room, calculating the required
17
treatment position, and moving the patient along a collision-free trajectory to the treatment position. Due to
resource limitations, further work on the software development of the robot control system was suspended,
however the development of the electronics for the robot control system is continuing.
Safety Interlock System
Work on the upgrading of the safety interlock system is proceeding very well. The new SABUS system with the
necessary digital input / output modules has been implemented. The changes to the software to accommodate
the new hardware have been implemented, tested and commissioned. The next phase in this project is to
replace the external PC with one of the new ETX computer modules and to adapt the software to run on the ETX
computer. Due to resource limitations, this work will have to be set aside until the software for the portal
radiographic system is completed.
Portal Radiographic System
The implementation of the final portal radiographic system was started. Parallelised implementations of both the
light slab and ray-casting algorithms for constructing digital reconstructed radiographs, as well as fast
implementations of the similarity measures, were produced. It was decided to use the mutual information
similarity measure in the final system. The calibration cube of the radiographic system was manufactured, and
the code required for the calibration of the system has been written and tested. The communication interface
between the radiographic system and the SPG system has been specified, and work is underway on
implementing a communication framework so that the necessary changes to the SPG system can be
implemented. Much of the overall program flow for the radiographic system has been specified, and a mock-up
of parts of the graphical user interface has been developed so that the graphical user interface design and the
overall program flow can be further refined. The electronics and software required to control the X-ray image
acquisition system have been fully developed and tested. All the electronic problems with the data acquisition
from the flat-panel detector and the synchronization interface between the detector and the high-voltage
generator for the portal X-ray tube have been resolved.
ETX Computer Module
The ETX computer module consists of an ETX (Embedded Technology eXtended) computer unit that is mounted
on a baseboard. The ETX unit is equipped with a Pentium-class processor and a comprehensive set of computer
peripheral and network ports. The baseboard provides customized interfaces for the ETX unit, including SABUS
(SA-bus), differential bus, a relay contact and 12 opto-isolated input and outputs. Permanent storage functionality
for the ETX unit is provided by a 4 GB compact-flash on the baseboard.
The ETX unit is also equipped with a PCI-bus interface, which was used to link it to the hardware of the interfaces
on the baseboard. This was done by developing and implementing a PCI target on a field-programmable gate
array (FPGA) on the baseboard. The PCI interface was successfully tested according to a subset of the tests
prescribed in the compliance checklist for Version 2.2 of the PCI specification. Only a subset of tests was used
18
since only a subset of the full PCI functionality was implemented in the PCI interface design. The ETX computer
design is stable and is ready to be used in new designs and existing systems. Five new modules are currently
being built.
Treatment Planning System
The upgraded treatment planning system for Windows-based workstations was completed. Although not yet fully
commissioned, it is already being used to do the bulk of the planning tasks, with only the final treatment plan of
each patient being recalculated on the old treatment planning system (see section 2.1.4 of this report).
Real-Time Range Controlling System
A grant was awarded by the NRF to aid the development of a new range controlling system for proton therapy in
collaboration with the Division of Radiation Physics and Engineering, Korea Institute of Radiological and Medical
Sciences (KIRAMS), Seoul (see section 2.1.5 of this report).
Dose Monitor Controller (DMC)
The development of a new dose monitor controller was started by specifying the overall design of the system and
defining the performance requirements for the two independent dose monitoring modules of the system. The
front-end electronics of each dose monitoring module has to measure very small currents with a large dynamic
range. This challenging requirement, along with the need for very accurate dosimetric measurements, requires
powerful simulation tools, such as PSpice, to facilitate, evaluate and compare the design of different front-end
topologies. The PSpice model for a front-end based on the venerable recycling integrator is far advanced. The
design and manufacturing of the digital back-end of the dose monitoring modules will be executed in conjunction
with the design of the front-end electronics. To ensure a speedy completion of the project, many design aspects
of the existing DMC will be retained in the less critical modules, such as the high-voltage power supplies for the
transmission ionization chambers and the interface with the therapy display console. One of the new ETX
computer modules will be utilized as the control computer for the DMC.
Monte Carlo Simulations
A major development for the Monte Carlo work in the Medical Radiation Group was the acquisition of two quad
core computers, making it possible to run eight simulations rapidly and simultaneously. Towards the end of the
year the Los Alamos National Laboratory (LANL) suspended the distribution of new β-versions of MCNPX (a
Monte Carlo N-Particle Transport code) indefinitely, just before the scheduled release of MCNPX version 2.7b.
This was unfortunate, as the tally-tagging capability of version 2.7b would have permitted discrimination between
the effects of primary and secondary charged particles – an important capability for the study of radiotherapy
dose distributions. However, a modification to the FORTRAN code to achieve the required tagging is available,
but has not yet been tested at iThemba LABS. Since LANL refused permission for MCNPX to be installed on the
Blue Gene supercomputer at the CSIR‟s Centre for High Performance Computing in Cape Town, greater use of
19
GEANT (GEometry ANd Tracking - a program for the simulation of the passage of particles through matter)
simulations is now envisaged.
CT / MRI Phantom
A phantom for evaluating the accuracy of software systems that fuse CT and MRI data has been designed and
manufacturing of the phantom is in progress. The phantom mimics the human head and neck, and consists of
different compartments to model various anatomical parts, such as the neck, head, brain, eyes, nasal and mouth
cavities, trachea and the spinal cord and brainstem. Although most of these compartments will be filled with
homogeneous fluids, the brain compartment will contain a highly heterogeneous insert that roughly mimics the
convolutions of the brain surface. The phantom will be equipped with a large number of fiducials that will be
clearly visible in both CT and MR images. The design also allows the marker carrier used for proton therapy to
be attached to the phantom, thereby making it possible to use the phantom to test the reliability and accuracy of
the SPG and portal radiographic systems.
Training
A highlight in our role in training was the member of staff, supervised jointly by staff from the University of
Stellenbosch and the Medical Radiation Group, who obtained his MSc in Applied Mathematics Cum Laude. The
topic of his thesis was “Fast generation of digitally reconstructed radiographs for use in 2D-3D image
registration”. Two students started Medical Physics internships with bursaries from iThemba LABS and two
others completed their „particle therapy‟ module with Medical Radiation. Another student started his PhD.
20
1.2.2 Radiotherapy treatment statistics
A total of 65 patients were treated on the p(66)/Be isocentric neutron unit during the year. A total of 13,4% (116
out of 864) of treatments had to be rescheduled. Problems which caused rescheduling are listed in Table 2.
Neutron therapy statistics are given in Table 1 and Figures 1-3.
Just three patients were treated on the 200 MeV horizontal beam proton therapy facility during the year. No
treatments had to be rescheduled. Proton therapy statistics are given in Figures 4-6.
Averages
Treatments per day
Fields per day
Fields per treatment
Time per field (min)
Time per day (min)
Neutron therapy
2008/2009
5.2
18.7
3.6
8.5
158
To date
6.7
18.6
2.8
11.0
206
Proton therapy
2008/2009
1.3
4.8
3.8
20.0
95
To date
2.7
7.7
2.9
17.6
136
Table 1 Hadron therapy statistics
Cause
SPM2 repairs
Beam line vacuum leaks
Power failures
SPC1 RF
SSC RF
Mains distribution boards
SPC1 slits
Beam stability
SSC resonator
Data link to vault
Treatment couch wiring
Number of treatments rescheduled
32
30
15
13
6
6
4
4
3
2
1
Table 2 Neutron therapy rescheduled treatments – Causes
21
160
1400
140
1200
120
1000
100
800
80
600
60
400
40
200
20
Completed Treatments
Patients Treated
70
600
60
500
50
400
40
300
30
200
20
100
10
0
Completed treatments
Patients treated
0
93/94 94/95 95/96 96/97 97/98 98/99 99/00 00/01 01/'02 02/'03 03/'04 04/'05 05/'06 06/'07 07/'08 08/'09
Year
Year
Figure 1: Treatment statistics of patients receiving neutron
therapy.
Figure 4: Treatment statistics of patients receiving proton
therapy.
120.0%
120.0
100.0%
100.0
80.0%
80.0
60.0%
40.0%
Rescheduled treatments
0
88
/8
9
89
/9
0
90
/9
1
91
/9
2
92
/9
3
93
/9
4
94
/9
5
95
/9
6
96
/9
7
97
/9
8
98
/
99 99
/
20 20 0
00 0
/2
00
20 1
01
/
20 2
02
/
20 3
03
20 /4
04
/
20 5
05
/
20 6
06
/
20 7
07
/
20 8
08
/9
0
Rescheduled Treatments
700
Patients
1600
Treatments per year
Patients treated
Treatments per year
60.0
40.0
20.0%
20.0
88
/8
9
89
/9
0
90
/9
1
91
/9
2
92
/9
3
93
/9
4
94
/9
5
95
/9
6
96
/9
7
97
/9
8
98
/9
99 9
/2
20 0 00
00
/2
00
1
20
01
/2
20
02
/3
20
03
/4
20
04
/5
20
05
/6
20
06
/7
20
07
/8
20
08
/9
0.0%
0.0
93/94
94/95
95/96
96/97
97/98
98/99
99/00
00/01
Year
01/'02
02/'03
03/'04
04/'05
05/'06
06/'07
07/'08
08/'09
Year
Figure 2: History of completed neutron therapy treatments
expressed as a percentage of those scheduled each year.
Figure 5: History of completed proton therapy treatments
180
200
160
180
160
140
140
120
120
Days
Days
100
100
80
80
Figure 2 - History of completed neutron therapy treatments
60
60
40
40
20
20
0
0
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
46
48
50
52
0
Fields per day
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
Fields per day
Figure 3: Frequency distribution of number of neutron therapy
fields treated per day.
Figure 6: Frequency distribution of number of proton therapy
fields treated per day.
22
Radionuclide Production Group
1.3 Radionuclide Production
1.3.1 Overview
The mission of the Radionuclide Production Group (RPG) of iThemba LABS is to develop methods to produce
high-grade radionuclides with the 66 MeV proton beam and to apply these methods to produce regularly, on a
weekly basis, radionuclides and radiopharmaceuticals for nuclear medicine in South Africa, and also to produce
longer-lived radionuclides for the export market to aid cost recovery. It includes the objective to sustain and
upgrade the production facilities, to increase the production yield while simultaneously reducing radiation
exposure to staff. As such, and in compliance with the mission of iThemba LABS, the group strives to pursue
active and internationally competitive in-house research, development and training programmes.
2007 - 2008
Activity
(mCi)
Consignments
Radionuclide
22Na
263
68Ge, 68Ge/68Ga
276
82Sr
24744
109Cd
2
88Y
10
Skids
0
Radiopharmaceuticals
123I
(Solution,
3948
Capsule & mIBG)
67Ga Citrate
6147
67Ga Resin
5
81Rb/81mKr
2430
generator
18F-FDG
3210
SUB-TOTAL
41035
Less Credits
2008 - 2009
Total
Income
(R)
Activity
(mCi)
Consignments
Total
Income
(R)
19
10
11
1
1
0
819 891
547 571
8 183 278
11 486
8 439
0
35
510
16793
0
0
2
7
16
8
0
0
1
61 669
1 608 557
6 240 434
0
0
22 415
422
795 233
4862
512
1 245 171
390
5
169
904 825
1 003
138 697
6339
2
2220
411
2
148
1 379 935
360
120 300
149
1178
999 313
12 404 740
-35 018
5347
36110
203
1308
1 465 947
12 144 788
-54 977
TOTALS
R12 368 722
R12 089 811
Table 1: Radiopharmaceuticals and radionuclides revenue
Relative to the previous financial year, the income generated from the sales of radiopharmaceuticals and
radionuclides had shown an overall consolidation above R12m (see Table 1). As shown in Figure 1 and 2,
relatively good growth was shown with
123I-related
products, 67Ga-citrate, 68Ge/68Ga generators and 18F-FDG
year-on-year, but substantial losses were shown with 82Sr and 22Na. The losses for 82Sr were mainly due to a
target (82Sr) that burst under high current in the Vertical Beam Target Station (VBTS). With the VBTS being out
of commission for four weeks, a loss of R2,5m of 82Sr sales to MDS Nordion (Canada) was realised. The losses
23
for 22Na solution and 22Na positron sources were due largely to the limited beam time to produce the product.
22Na
cannot be produced whilst the demand for 82Sr is high. In recent times residual 22Na stock from previous
years were sold and we only expect to recommence the production of 22Na should the demand for 82Sr drop or
Activity (mCi)
when the beam splitter is fully commissioned.
7000
5000
3000
2005/2006
1000
2006/2007
-1000
2007/2008
2008/2009
Radiopharmaceutical
Figure 1: Radiopharmaceuticals Activity Trends
Figure 2: Radionuclides Activity Trends
Distributor agreements for
68Ge/68Ga
generators were maintained with IDB-Holland B.V. (European and
Australian markets) and new contacts were established with iSoSolutions (North and South American markets),
B.J. Madan & Co and Saxons Pty Ltd (India market), Taiwan Life Support Systems (Taiwan market) and
QT Instruments (Singapore, Malaysia and Thailand markets).
iThemba LABS continues to supply radiopharmaceuticals to the local public hospitals at a 40% discounted price,
and continues to provide a free supply of 81Rb/81mKr generators (used for lung ventilation studies) to Groote
Schuur Hospital on a weekly basis, because of their severe budget constraints. For the review period, more than
1 300 consignments were dispatched to over 120 clients worldwide and the delivery of consignments correctly
and punctually was maintained at 93% year-on-year (Figure 3). Non-delivery or delayed delivery was mainly
24
attributable to a) unscheduled power outages, b) cyclotron downtime, c) breakdown of ageing equipment and
infrastructure related to targetry and chemistry.
Figure 3: Service delivery percentage of radiopharmaceuticals and
radionuclides
In February 2009, a rubidium metal target failed on the Vertical Beam Target Station (VBTS), leading to some
station infrastructure damage as well as a loss of income as two orders for 82Sr from MDS Nordion (Canada)
could not be delivered. This was the third recorded VBTS target failure since high-intensity bombardments
commenced on that target station in 2006. During the time that the VBTS was down, all beam time allocated to
that facility was still utilised, however, by bombarding a magnesium target (producing 22Na) in another target
station.
Although relatively few target failures occur at the RPG, each event has very serious consequences. Not only is
that particular production and the corresponding income lost, but customers who rely on our products are
disappointed, and repairs have to be perform under harsh radiological conditions. In fact, a down time of typically
4 weeks is required before repairs on the VBTS can commence, in order for the dose rate from shorter-lived
activation products to decay, while the actual repair work usually takes only a few hours to complete.
It is often very difficult to determine the cause of a target failure. Such an event usually happens very rapidly and
destructively and trying to determine the cause by studying the debris is usually inconclusive. Ideally one would
expect that the various procedures, kinds of monitoring equipment and other engineered systems, would give
prior warning and/or take action automatically before damage occurs. At iThemba LABS, very advanced
diagnostic systems are used to monitor the beam. Likewise, many parameters of the station are monitored and
logged during a bombardment, such as the beam position (according to current readouts from a four-sector
collimator), beam current and accumulated charge, the flow rate, pressure, temperature and conductivity of target
cooling water, radiation levels in the vault, air and helium pressures, etc. The important parameters are all
interlocked with the beam, therefore, should a parameter suddenly fall outside specific set levels, the beam will
trip. The majority of potentially disastrous events are certainly prevented by these measures. Unfortunately, not
all important parameters can be monitored, interlocked and logged, e.g. metal fatigue of targetry components. A
long-standing concern is the number of thermal cycles some of the targets used in the production of long-lived
25
radionuclides are subjected to. Radiation-induced corrosion is another incredibly difficult factor which is virtually
impossible to monitor. This is, in fact, true for other forms of radiation damage as well, e.g. damage to pneumatic
components.
It remains a continuous task to keep all three bombardment stations operational at the RPG, since some of the
infrastructure is quite old. Manufacturing of replacement components is an ongoing activity and improvements
and/or upgrading are performed whenever possible. Improvements to the monitoring and interlocking are also
ongoing, e.g. a recent implementation of a counter to monitor the number of thermal cycles on a target, improved
monitoring of the beam sweep by increasing the sampling rate, etc.
A serious attempt is also being made to understand the targetry better and to improve it. Not all the infrastructure
required to manufacture VBTS targets exists at iThemba LABS, thus, some work is sourced out. The various
components of the Rb target capsules used for 82Sr production, for example, are welded together by the National
Laser Centre of the CSIR. The filling of these capsules with Rb metal as well as some of the quality control of the
assembled targets is done by MDS Nordion staff at the TRIUMF facility, Vancouver, Canada. A method to
investigate activated target components based on an autoradiographic technique using Gafchromic EBT film and
the Doselab software (presented by the Edmonton PET Centre at the 12th International Workshop on Targetry
and Target Chemistry in July 2008) was introduced at iThemba LABS. Using this method, the VBTS sweeper
magnets were properly characterized (shown in Figure 4). The beam profile on a typical VBTS target is shown in
Figure 5. Finally, Figures 6 and 7 show a failed target and a failed beam line component, respectively.
Figure 4: Autoradiographs of a 66 MeV proton beam in the VBTS, obtained by exposure of Gafchromic EBT film to the
radiation from activated foils. The current of the sweeper magnets is progressively increased from (a) through (f), from zero to
the maximum of the respective power supplies. The size of each square is approximately 45 mm by 45 mm. The beam
intensity was low for this study and the beam was also sharply focused.
26
Figure 5: Autoradiograph of a Mg target capsule irradiated in the VBTS. The target was bombarded repeatedly over a period of five
weeks to an accumulated charge of 50 000 μAh, the highest charge yet on any VBTS target. In this case, no structures other that the
expected circular sweep is visible in the beam profile.
Figure 6: A failed VBTS target capsule. In this particular case, the beam sweeping radius was too small. A hole is clearly visible
in the darkened region on the face of the target. The photograph was taken through the 20 cm thick lead glass window of the
reception hot cell.
Figure 7: A badly damaged electron suppression ring. This component was located upstream from one of the bombardment
stations. Damage is visible both to the left and right sides of the aperture, indicating that the high-intensity beam moved quite far
from the centre. Some material melted on the right side.
27
The RPG operates three bombardment stations routinely for the production of radiopharmaceuticals and
radionuclides. Table 2 and Figure 8, 9 and 10 shows the beam time allocation of the various targets for both the
horizontal beams and vertical beams.
Table 2: Production parameters relevant to target bombardments.
Figure 8: Beam and beam-time utilised per radionuclide.
28
Figure 9: Percentage of total accumulated charge per production type for horizontal beams.
Figure 10: Percentage of total accumulated charge by bombardment for vertical beams.
29
1.3.2 Major Achievements
 Revenue for the sales of radiopharmaceuticals and radionuclides consolidated above R12,0m.
 The service delivery of radiopharmaceuticals and radionuclides was maintained at 93% efficiency.
 Distributor and Supply Agreements for 68Ge/68Ga generators were maintained with IDB-Holland B.V. and new
distributor contacts were established with iSoSolutions, B.J. Madan & Co, Saxons Pty Ltd, Taiwan Life
Support Systems and QT Instruments.
 RPG collaborations with Hungary continued and new bilaterals with South Korea and African countries such
as Algeria and Lesotho were established.
30
Materials Research Group
1.4 Materials Research Group
1.4.1 Overview
The Materials Research Department (MRD) is a multidisciplinary research group at iThemba LABS which
conducts both basic and applied materials research by probing various aspects of matter using a wide range of
ion beam analytical techniques such as the Nuclear Micro-Probe (NMP), Rutherford Backscattering Spectrometry
(RBS), Particle Induced X-Ray Emission (PIXE), Heavy Ion Elastic Recoil Detection Analysis (HI-ERDA), etc. In
addition, a wide range of material surface and structural characterization techniques, viz. X-ray diffractometry,
Scanning Probe Microscopy, Mössbauer Spectrometry, Pulsed Laser Deposition and Electro-spinning Deposition,
permit the MRD to conduct a number of research projects in the specialized fields of Nanotechnology, Materials
Engineering, Geological and Bio-medical sciences. The facilities of the MRD thus enable iThemba LABS to
achieve its fundamental objectives in the critical areas of research capacity development and postgraduate
student training through synergistic partnership with local and international Industrial Councils and tertiary
institutions of Higher Learning. The following are some of the MRD highlights for the period under review.
1.
From 19 to 23 September 2008 the MRD successfully hosted an International Centre for Science and High
Technology – United Nations Industrial Development Organisation (ICS-UNIDO) funded nanotechnology
conference event under the title “Nanotechnology Regional Networking to have Better Access to
Knowledge Information Technology”. Organized jointly with the International Center for Theoretical
Physics (ICTP), the conference participants included representatives of Chinese, France and Italian
embassies, as well as a wide range of eminent international scientists and experts in the field of
nanotechnology. The event was opened with a keynote address by the Minister of Science and
Technology, Dr Mosibudi Mangena.
2.
Following an NEP award of R1,132m by the NRF to upgrade the X-ray Diffraction laboratory, the first
phase of the commissioning process was commenced in December 2008. The current upgrade consists
of two principal items, viz. a heating stage for in situ measurements coupled with a new position sensitive
detector for fast data acquisition. The new position sensitive detector was installed in mid-December
2008. The old X-ray tube which had been in use for more than three years had to be replaced in order to
achieve proper calibration of the newly installed position sensitive detector. The commissioning process
was put on temporary hold in the last quarter of the 2008 financial year due to the supplier‟s tight service
schedule. The commissioning process is scheduled to resume by end of May with the commissioning of
the “heating stage” part of the upgrade. It is expected that the current phase of the upgrade will be
completed by no later than the end of the 2008 academic year.
3.
In December 2008 the MRD was awarded a R3,6m grant by the NRF from the National Nanotechnology
Equipment Programme to purchase a Physical Properties Measurement System (PPMS). Once installed,
the PPMS equipment will permit the MRD to perform electrical measurements at a cryogenic base
temperature of 1,9k. A closed He-4 system, the PPMS will also be equipped with a superconducting
31
solenoid which permits application of magnetic fields up to 9 Tesla. The multi-tasking capability of the
PPMS is expected to benefit a range of MRD in-house nanotechnology-based research projects. A
purchase order for the PPMS has been submitted to Cryogenics Company in the United Kingdom.
4.
A Heavy Ion – Elastic Recoil Detection (HI – ERD) analysis equipment set-up has been established as
one of the MRD‟s most suitable analytical techniques for non-destructive simultaneous analysis of light (H2
to Ne) elements in thin film matrices. The measurement set-up, based on the Time of Flight – Energy
spectrometry technique, has been completed at iThemba LABS as part of M Msimanga‟s PhD project for
applications in HI – ERD, presenting a most suitable complimentary technique to the existing RBS and
PIXE nuclear analytical techniques at the MRD. The HI-ERD setup has thus far been used successfully to
measure the thickness of a refractory layer of CaF2 deposited on a silicon substrate. A clear 2D Time of
Flight - Energy scatter plot of target atoms recoiled by a 27.5 MeV Kr15+ beam incident on the target
sample at a grazing incidence angle of 15 was obtained, from which energy spectra were extracted of the
identified recoils, including oxygen and carbon native impurities. The thickness of the deposited layer,
deduced from the width of the Ca energy profile was measured to be (740 ± 40) x 1015 at/cm2 or
210 ± 10 nm.
A comparative measurement using the more established Rutherford Backscattering
Spectrometry technique gave a thickness value of 750.0 x 1015 at/cm2 (212 nm). Development and
implementation of the data analysis procedure are in progress.
5.
A Magnetic Force Microscopy (MFM) starter kit, consisting of a tip magnetizer and ten magnetic probes,
was acquired in order to activate the MFM capabilities of the Atomic Force Microscope (AFM) at the MRD.
The MFM is a proximal probe imaging technique by which a magnetized tip is used to image spatial
variation of magnetic forces on the sample surface. The MFM technique is widely used to image both
naturally occurring and artificially induced structures of magnetic domains on devices such as magnetic
data storage discs and tapes. With the MFM imaging technique activated, the AFM at the MRD is now
routinely used to capture simultaneously a pair of surface images with magnetic force and topographic
information independently resolved. Using both the interleave and the lift-mode scanning techniques, a tip
undergoes four scan lines, with the first two trace and retrace scans used to record the conventional
topographic data, and the remaining two scans used to capture magnetic force variation. Clear MFM
images have been obtained on both nickel and cobalt thin films prepared in-house using the e-beam
evaporator.
6.
During the period under review, a number of MRD staff members and postgraduate students received
special awards:
(a)
Professor M Maaza was appointed and confirmed as an American National Science Foundation
international partner of the Centre for Functional Nanoscale Materials - Clark Atlanta University
(CFNM-CAU CREST) with effect from January 2009. The appointment allows official postgraduate
students exchange between the CFNM-CAU CREST and MRD - iThemba LABS from January
2009.
32
(b)
J Sithole, an ALC-sponsored PhD student, was awarded the “Taylor & Francis Award” for
outstanding research work presented at the 2008 International Fine Particles Conference held at
Laguna Beach in Cape Town. Sithole‟s award included the certificate of recognition jointly
presented by the Taylor & Francis Group together with the Journals of Toxicology and
Environmental Health in recognition of the outstanding achievement of the recipient in the field of
nano-photonics.
(c)
M Msimanga won the Frank Nabarro PhD oral award for the best PhD oral presentation in the
Condensed Matter Specialist group at the 53rd South African Institute of Physics conference held at
the University of Limpopo in July 2008.
(d)
Dr Carlos Pineda-Vargas was admitted as Adjunct Professor at the Faculty of Health & Wellness
Sciences at the Cape Peninsula University of Technology (CPUT) for the period 2008-2010. The
appointment also allows Dr Pineda-Vargas to serve as the official CPUT liaison contact for Ion
Beam Analysis at iThemba LABS.
(e)
Dr R Nemutudi was appointed a board member of the National Metrology Institute of South Africa
which is based at the CSIR in Pretoria.
7.
During the period under review, the MRD made the following staff appointments:
(a)
Dr A Nechaev was appointed on a two-year contract as a postdoctoral researcher in Nanosciences.
(b)
Professor C Pineda-Vargas was appointed a full-time senior research scientist in Ion-Beam
Analysis.
(c)
Dr R Nemutudi was appointed head of the MRD after serving as the interim head of the department
for a period of eighteen months.
33
Physics Group
1.5 Physics Group
1.5.1 Overview
The main activities in the Physics Group at iThemba LABS are research and training (mainly at postgraduate
level) in basic and applied nuclear physics. The basic research being conducted is aimed at expanding
knowledge about nuclear reaction mechanisms and nuclear structure. Particle beams supplied by the injector
and separated sector cyclotrons (SSC), along with experimental facilities managed by our group, are used for this
research. The major facilities include a K600 magnetic spectrometer, the AFRODITE gamma-ray detector array
and the large A-line scattering chamber. In order to produce and store targets needed for SSC-related research,
a target laboratory with a dedicated target maker is operated by the group. The group also conducts research on
theoretical nuclear physics. In this regard we have maintained a focus on clustering phenomena in nuclei and the
modelling of rapidly rotating nuclei. Our group is also formally linked to the research programme around physics
that can be studied using the ALICE detector associated with the Large Hadron Collider at CERN.
The applied research is conducted in the Environmental Radioactivity Laboratory of our group, and by means of
neutron (secondary) beams produced via protons (from the SSC). In the Environmental Radioactivity Laboratory,
research is conducted into natural and anthropogenic radioactivity in the environment (mainly soils, sediment and
water). The main techniques used are in situ and ex situ gamma-ray spectrometry. The Environmental
Radioactivity Laboratory also performs routine measurements of environmental samples for the Radiation Safety
Division at iThemba LABS. Applied neutron-related studies are aimed at studying the biological effects of ionizing
radiation and the intercomparison of dosimetry systems. In order to complement mainly the applied research we
also conduct research around the use of Monte Carlo simulation techniques to model the interaction of radiation
with materials.
During the period covered by this report Richard Newman continued to act as interim head of the group in the
light of the promotion of Kobus Lawrie to deputy director. Paul Papka resigned from iThemba LABS in
September 2008 and joined the Department of Physics at the University of Stellenbosch as a senior lecturer.
Evgenia Lieder resigned as a postdoctorate and left iThemba LABS at the end of November 2008. Israel
Hlatshwayo was promoted to junior scientist in the Environmental Radioactivity Laboratory (from 1 December
2008) and Joele Mira was appointed as junior scientist (with a focus on the light-ion physics programme) from
January 2009. Pradip Datta was appointed as a postdoctorate (with a focus on nuclear structure studies) in
February 2009.
In the reporting period there were 19 full-time postgraduate students (11 at masters and 8 at doctoral level)
registered at South African universities who made use of our group resources to conduct their research. Of
these, seven were black South African students (as classified by the Employment Equity Act), three were female
and eight were foreign students (from the wider African continent).
During the year three masters level students were awarded their degrees. Nine staff members from our group
are also lecturing and organizing practicals for students in the Masters in Accelerator and Nuclear Science
34
Physics Group
(MANuS) programme which is jointly organized by iThemba LABS and the Universities of the Western Cape and
Zululand.
The group was associated with 18 contributions at local and nine at international conferences. During this report
period 21 journal articles (14 as part of conference proceedings) were published from research conducted by the
group.
1.5.2 Highlights
1.
Some molecules form three-dimensional structures with well-defined chirality, (or handedness), e.g. two
molecules might be a reflection of each other, but at the same time are not identical, for example our right
and left hands. Whether nuclear matter can show such phenomena, however, is yet to be verified.
Nuclei, when they rotate, emit sequences of gamma rays, called rotational bands. If the nucleus is chiral,
two degenerate (identical) rotational bands with certain properties should be observed. In order to detect
the emitted gamma rays, large arrays of gamma-ray detectors are employed. Thus far many nuclei have
been proposed as possible candidates for chiral symmetry. Their gamma-ray emission has been studied
around the world, but in none of the suggested cases can the rotational bands be called truly identical.
Whether this means that chirality does not exist for nuclei, or whether the phenomenon is more
complicated and other additional effects cause the doublet bands to differ slightly from each other, is a
topic of debate at present. Recently the AFRODITE gamma-ray array, which is operated by our group,
was used to study the gamma-ray emission of the 198Tl nucleus (containing 81 protons and 117 neutrons).
We found two rotational bands with similar structure and suggested that these form the first candidate pair
of chiral bands in this mass region of very heavy nuclei [E A Lawrie et al., Phys. Rev. C 78 (2008)
021305(R)].
2.
A free -particle, which is the nucleus of the atom of helium, is particularly stable. In heavier atomic
nuclei, this fact leads to theories that postulate the existence of -clusters, which may display some
resemblance to -particles. These -clusters are systems of two-proton, two-neutron pairs in nuclear
matter that would form a single entity, but only for a brief period. A very important question is to what
extent bound -clusters retain properties associated with a free -particle. This issue, for 12C, was
resolved in a recent careful measurement of the left-right scattering asymmetry in the knockout of
-clusters from 12C by polarized protons. It was found that in all respects the projectiles interact with the
clusters as if they were free entities. This result provides compelling and direct evidence for the existence
of preformed -clusters in the atomic nucleus 12C [A A Cowley et al., EPL 85 (2009) 22001; 1-5].
3.
For three months from September 2008, iThemba LABS hosted two IAEA Fellows from South America,
Dr Cristian Pavez Morales, a plasma physicist from Chile, and Angel Cruz Silva, an MSc student from the
University of Bogota, Colombia. They received training in the use of the HYDAD-D landmine detector
(F D Brooks and M Drosg, Appl. Rad. and Isotopes 63 (2005) 565) now being developed and tested at
iThemba LABS with the help of Emeritus Professor Frank Brooks (UCT) and Charles Wikner (a former
iThemba LABS staff member). HYDAD detectors incorporate a radioisotopic source of fast neutrons and
35
Physics Group
can detect slow neutrons backscattered from
small antipersonnel landmines buried at depths
of up to 15 cm in dry ground. HYDAD-D was
tested and compared with other types of
landmine detectors in Egypt in 2007, using real
landmines, and proved very successful. A copy
of the HYDAD-D equipment was constructed and
tested at iThemba LABS, then shipped to Chile
after the training course. Morales plans to use
this equipment for tests in which a plasma-focus
neutron source will replace the radioisotopic
neutron source used at iThemba LABS. Such an
Figure 1: The two IAEA Fellows at iThemba LABS, testing
their newly acquired skills at using HYDAD-D.
arrangement promises to be more convenient for use in the field, because this neutron source can be
“switched off” when not in use. The work carried out by Cruz Silva at iThemba LABS will form part of his
studies at the University of Bogota (see Figure 1).
4.
On 4 July 2008 the ALICE collaboration board officially approved, at their meeting at CERN, the extension
of the former UCT - ALICE collaboration to the UCT - iThemba LABS - ALICE collaboration. As part of the
ensuing memorandum of understanding, scientists from UCT and iThemba LABS are members of the
ALICE Dimuon Group. The ALICE Dimuon Spectrometer is designed to accommodate 10 high-resolution
cathode pad tracking chambers, a large warm dipole magnet, front absorbers, muon filter and two sets of
low-resolution trigger chambers. The UCT - iThemba LABS - ALICE collaboration is currently active in
making simulations to optimize the trigger to use when data taking commences.
5.
Dr Simon Mullins, a senior scientist in our group, was successful in acquiring a grant of R4m from the
DST, as part of the SA-JINR (Dubna) programme, to purchase new state-of-the-art hyperpure germanium
detectors for use in the AFRODITE gamma-ray detector array. AFRODITE is used mainly to study the
behaviour of rapidly rotating atomic nuclei. The new detectors will significantly increase the sensitivity of
the array.
6.
The following students won the prizes in the Nuclear, Particle and Radiation Physics section at the 2008
South African Institute of Physics conference which was held at the University of the Limpopo:
Paulus Masiteng (UWC, best oral presentation by a PhD student), Sifiso Ntshangase (UCT, second best
oral presentation by a PhD student), Susan Bvumbi (UWC, best oral presentation by a MSc student) and
Jacobus Swartz (SU, best poster by a MSc student).
7.
In March 2009 a memorandum of agreement was concluded between iThemba LABS and UCT to pave
the way for the establishment of a positron emission particle tracking (PEPT) facility at iThemba LABS.
The PEPT facility will be operated by UCT Physics Department staff, and iThemba LABS will supply the
positron emitting sources. An ECAD „EXACT3D‟ PET camera will be relocated from Hammersmith
Hospital (United Kingdom) to the iThemba LABS-based PEPT facility. The camera consists of six rings of
BGO detector blocks, each sectioned into 8 x 8 elements (27 648 in total), with a ring diameter of 820 mm,
producing an axial field of view of 234 mm. Commissioning of the camera is expected during the course of
2009.
36
iThemba LABS (Gauteng) Group
1.6 iThemba LABS (Gauteng)
1.6.1 Performance Summary
iThemba LABS (Gauteng) is a new research department in the process of being fully integrated within iThemba
LABS. This process began in January 2005 after the transfer of Wits University‟s then Schonland Research
Centre for Nuclear Sciences (SRCNS) to the National Research Foundation (NRF). The integration was realized
after the Department of Science and Technology (DST) committed funds to the amount of R16m towards the
refurbishment of critical research infrastructure such as the 6 MV Tandem Van de Graaff accelerator and other
related facilities / equipment, with the primary objective being the realization of Accelerator Mass Spectrometry
(AMS), which is expected to take about 60% of the beam-time. Other areas of research will include experiments
in Rutherford Back Scattering (RBS), Nuclear Reaction Analysis (NRA), Channelling and Particle Induced X-Ray
Emission (PIXE). Accelerators at the University of Pretoria and at Necsa will also be used in some of these
research areas, through formal agreements with these institutions.
1.6.2 Highlights
Major Highlights during the period covered by this report are:
1.
Completion of the microprobe beam-line. The micro-probe is the second beam-line, after the completion
of the nuclear physics beam-line in 2007. The greatest challenge at the moment is getting the Microprobe up and running so as to
increase the user base of the
Gauteng facility.
The complete
hardware section of the micro-probe
beam-line is as shown in the figure.
The latest version of Oxford Microbeams Data Acquisition (OMDAQ
2007)
system,
and
associated
electronic modules (e.g. Analogue to
Digital Converters) purchased from
Oxford Micro-beams, in the United
Kingdom, arrived in the country in mid-January 2009. The Data Acquisition system has been installed and
the beam-line has been aligned and leak tested. What remains is running some tests and calibrations
using standard samples. The equipment boasts the latest state-of-the-art innovations in micro-probe
measurements. The chamber has a motorized XYZ stage (where samples are mounted), comprising
three-axis stepper motors with encoded shafts that allows better than two-micrometer repeatability. In
addition to the three-axis stepper motors, there is an integrated manual rotation stage allowing 360 degree
rotation about the Z (vertical) axis, which allows channelling experiments to be conducted with a high
degree of accuracy. The micro-probe will be used in the areas of Rutherford Back Scattering (RBS),
37
Elastic Recoil Detection Analysis (ERDA), Proton Induced X-Ray Emission (PIXE), and Channelling
experiments. Scientists will span a broad spectrum of science fields.
2.
Advancement towards the realisation of Accelerator Mass Spectrometry (AMS). An equipment grant
proposal of R4,7m was submitted to the NEP Programme of the NRF in June 2008 for the purchase of a
High Energy Analysis System and Sample Preparation Laboratory for AMS. The proposal was successful
with a grant of R4,5m awarded by the NRF.
3.
Energy calibration of Tandem accelerator. The Nuclear Physics beam-line is the first to be rebuilt after the
refurbishment of the 6 MV Tandem Van de Graaff accelerator. The early completion of the Nuclear
Physics beam-line was primarily aimed at testing the integrity of the refurbished accelerator. The first
calibration experiment using oxygen on a carbon target and detecting alpha particles has been completed
successfully. The second calibration experiment, now under way, uses a proton beam on aluminium and
detecting neutrons.
4.
A research project on creating
Photovoltaic (PV) nanoparticles
using
spray
pyrolysis
was
introduced in 2009. The figure
on the right shows the spray
pyrolysis equipment. This is part
of a bigger project on the
synthesis and characterization of
solar cells and is a collaboration
between the Fort Hare Institute
of Technology, the University of
the Witwatersrand, CSIR and iThemba LABS (Gauteng).
1.6.3 Human Resources
During the 2008/9 year, Dr I Machi, Group Head, iThemba LABS (Gauteng) resigned and joined the National
Institute for Higher Education (NIHE) in Mpumalanga. Dr M Madhuku and G Badenhorst were appointed Interim
Group Head and Interim Deputy Group Head, respectively, from 1 January – 31 May 2009. Dr S Mullins has been
appointed substantive Group Head with effect from 1 June 2009. Also the joint appointment with Wits University
of Professor E Sideras-Haddad, who will be involved mainly in AMS and Nuclear Microprobe developments, is at
an advanced stage. The following important positions were also filled during this period: Electronic Engineer and
Divisional Head: Technical (G Badenhorst) and Librarian (M Mahlare).
38
1.6.4 Operational Highlights
In addition to the developments in Section 1.1, which are core to iThemba LABS (Gauteng), advancement in
other sections of the laboratory includes analytical divisions of the Environmental Isotope Laboratory (EIL) and
Geology. Hundreds of samples (generating income of around R500k annually) are being analysed in the EIL.
Various research projects associated with the EIL are listed below. These projects are in addition to analysis of
commercial samples from various institutions such as the Department of Water Affairs (DWAF) and the IAEA, to
mention a few.
Research Projects in the EIL
1.
The IAEA Technical Co-operation programme SAF2005012 Thukela, South Africa (the “Thukela Project”).
The project aims to define and quantify the sources, pathways and travel times of components of the
hydrological cycle in the Thukela basin and investigate the feasibility of using river monitoring data as a
diagnostic tool in defining the catchment response.
2.
The company that has been given the tender to monitor the ground water at future PBMR sites will be
sending samples on a monthly basis for the next five to six years.
3.
A study on the Johannesburg-Pretoria Dome will be conducted in conjunction with the University of the
Witwatersrand Geosciences Department. The first sampling trip was undertaken on 22 April. Surface
water samples in the Crocodile River catchment were collected. A draft paper has been compiled which,
once finalized, will be submitted to the Journal of Hydrology.
4.
Establishment of a monitoring system for surface and groundwater in the Cradle of Humankind (COH)
World Heritage Site (WHS).
The World Heritage Convention Act obliges Government to ensure an appropriate balance between
protection and development of the COH WHS. Unprecedented development pressure in and around the
COH WHS is placing the character of the area as an unspoilt tourism destination at risk. Discharge of
effluent, particularly acid mine drainage, pose a potential threat to the sensitive dolomites of the COH
WHS. It is hoped to achieve the following:

Both groundwater and surface water monitoring systems that are localized to achieve best
representation of the hydrological system.

Improvement of water quality and stable groundwater levels.

Achievement of the acceptable standard limits for both surface and groundwater (compliance with
national water standards).

Protection of the Karst system regarding water quality, quantity and water levels.

Modelling of the Karst system.

Compliance with UNESCO requirements regarding the state of the environment in the COH WHS.
39
5.
The use of isotope hydrology to characterise and assess water resources in south(ern) Africa.
The use of isotope hydrology, as a tool to assess water resources in South Africa, which at one stage
developed into a national asset and enjoyed international recognition, has been declining in recent years,
due to several factors (viz. institutional changes, available instruments, human resources and funding).
The principal object of this project is to build awareness and interest in the field of isotope hydrology, from
the point of view of its application and also as a tool in academic research. To this end this project
proposes to (re-)assess the water resources of selected areas, where possible building on existing and
earlier, often uncompleted studies, information and data. The other main aim is to re-establish and
develop the required manpower capacity to analyse and interpret isotopic data and information.
Research Projects in Geology
The research activities in Geology have been carried out largely off site, and are driven by Dr Rodger Hart. The
work has centred mainly on collaborative projects with scientists from the Institut de Physique du Globe, in Paris.
The major project in this field is aimed at “Super Magnetic rock from the Vredefort meteorite crater, South Africa”.
The project is centred on understanding the development of both crystal magnetization and gravity features in the
crust. This is essential in interpreting continental scale terrain boundaries which manifest themselves either as
major magnetic or gravity anomalies.
Ion Implanter
Work on repairing the Ion Implanter
was completed by Wits School of
Physics staff (Mervin Naidoo, Trevor
Derry and technician Tony Voorvelt),
according to the arrangement made
with Isaac Machi.
The machine is
under test with implants limited to the
needs of Wits Physics research
students for the time being, but is
running well again.
40
Electronics and Information Technology Group
1.7 Electronics and Information Technology
During the review period the number of general power outages was significantly less than the number
experienced the previous year due to the national electricity supply crisis. Nevertheless, as a precautionary
measure, a second 10 kVA uninterruptable power supply (UPS) was installed to provide additional reliable power
to the computer server room. The supply to this UPS is sourced via a circuit which switches to one of iThemba
LABS‟ standby generators in the event of a general utility power failure.
iThemba LABS is a member (together with partners in the physics community based in some local universities)
of the SA Academic Grid Consortium project, which will create an infrastructure of many cooperative computer
systems providing the ability to perform sorting and analysis of large amounts of data and complex computer
simulations. iThemba LABS is also a member of the SA-CERN consortium, and in particular, is actively
participating in the area of the high-performance computing for the physics applications component of this
partnership. As part of this initiative a small computer cluster was purchased and installed in the data room
annexe. Extra air conditioning was also installed in this room to reduce the risk of overheating following failure of
the main air-handling system. Reliable power to the cluster is supplied from one of the 10 kVA UPS's.
The frustrations due to iThemba LABS‟ limited Internet access bandwidth have continued for staff and users of
the facility alike. The affordability of appropriate bandwidth has been the limiting factor up to the present. The
deployment of the new SANReN national research network infrastructure has experienced repeated delays. To
alleviate some of the congestion experienced by users of a few critical applications, two (relatively slow) ADSL
services were installed during the year. A faster ADSL service was installed at iThemba LABS (Gauteng) as its
main Internet access circuit. However, general congestion will only be overcome once a fibre-optic access circuit
is installed to connect iThemba LABS‟ Faure facility to the (still to be commissioned) SANReN national backbone.
It is hoped that progress will be made on this front by the end of the current year. Developments in the provision
of significantly enhanced affordable international Internet bandwidth are also promising and should bear fruit
during 2009.
Financial constraints have limited the development of iThemba LABS‟ local area network (LAN) infrastructure.
The backbones on the two campuses consist of fibre optic cable segments operating at 1 Gb/s, which connect
multiple VLANS via managed switches delivering 100 Mb/s or 1 Gb/s copper utp connections to the offices, etc.
With the increasing demands on LAN-LAN connections, as well as the rapid expansion of LAN-WAN connections
once the SANReN infrastructure is deployed, the upgrading of iThemba LABS' core backbone network is
becoming urgent.
There are currently in excess of 500 active personal computer workstations, desktops and servers on site. The
managing of the demands of users of these facilities places a considerable load on the staff of the support
division. A “request tracker” system was implemented to expedite the servicing of this workload. This system
has worked well, and currently the call rate handled is close to 100 per month.
Work on the use of EPICS as the platform on which future accelerator control software will be developed at
iThemba LABS has continued. EPICS (Experimental Physics and Industrial Control System) is a distributed
41
computer control system collaboratively developed at a number of accelerator-based laboratories around the
world over a number of years. Currently, EPICS development efforts are being very actively pursued in
numerous laboratories.
EPICS-based developments of the iThemba LABS' accelerator control systems have included:
1.
A subsystem to control beam scanners installed in the beam lines of the electrostatic accelerators, and to
acquire and monitor data from these beam scanners.
2.
The control of components in the new cyclotron beam splitter.
3.
The development of software drivers for locally designed and manufactured interface controllers.
4.
The provision of standard EPICS record type interfacing to a number of laboratory-designed controller
modules.
5.
The development of a software bridge between the new EPICS process variables and the old control
system‟s variable table.
6.
The subsystem to control, and display information from, beam-line harps and Faraday cups.
7.
A start to the migration of the Gauteng facility‟s tandem electrostatic accelerator control system to the
EPICS platform.
The safety interlock system of the Gauteng tandem accelerator has been upgraded and new devices added,
while a new safety interlock system for the Radionuclide Department has been developed and will be installed
and tested once all the required wiring has been completed. New software has also been developed to test many
of iThemba LABS‟ in-house and commercial electronic modules used in the accelerator control systems.
Work on the development of new data acquisition subsystems (DAQ) for research users have focussed on four
projects:
1.
A pxi-based DAQ to acquire data from experiments on the Afrodite gamma-detector array.
2.
A VME-based DAQ to acquire data from experiments on the K600 magnetic spectrometer using a fast
real-time kernel in the front-end to handle the required data rates.
3.
A DAQ for the channelling / RBS experiments performed on the Faure electrostatic accelerator.
4.
A new DAQ system for the microprobe facility on the Faure electrostatic accelerator.
A computerised visitors' access system for use at the main entrance gate was developed, and successfully
implemented at the beginning of 2009.
The electronics support division provided a service to the whole of iThemba LABS and several external users of
its facilities. The division has also played an important role in the design, manufacture and testing of electronics
subsystems to be used in several major iThemba LABS projects. These have included:
1.
The support of the research users‟ instrumentation requirements.
2.
The development of a VME bus analyzer and tester.
42
3.
Upgrading the power specifications to the Afrodite and magnetic spectrometer vaults, and the cleaning up
of the earth connections to the instrumentation in these vaults.
4.
The design and construction of numerous analogue and digital modules required for the accelerators‟
control subsystems.
5.
The installation, customization and debugging of the control system of the donated Hahn-Meitner Institute
ECR ion source.
6.
The design and construction of several electronics subsystems required for the upgrade of the proton
therapy programme for the Medical Radiation Department.
EIT Department staff members were involved in teaching the electronics modules in the MANuS and MatSci
courses at the University of the Western Cape. Topics included basic analogue and digital electronics, control
systems and electronic interfaces used in accelerator control systems, and experimental physics instrumentation.
Practical sessions were held at iThemba LABS on analogue, digital and control electronics using National
Instruments NI-Elvis training stations. A post-graduate student working on an iThemba LABS-based EIT project
graduated with a MSc from the University of Cape Town. Two collaboration students from the National University
of Lesotho worked on EIT projects.
Four electrical engineering national diploma students studying at CPUT (Cape Peninsula University of
Technology) were placed in the EIT Department for their 12-month in-service training. Six Office Management
and Technology students spent six months each of their experiential training in the library.
In the iThemba LABS‟ International Computer Driving Licence (ICDL) teacher training programme, more than
150 teachers and 14 Khanya facilitators were trained. Some 21 Edunova facilitators were also trained. Edunova
is a local organization that assists Khanya in the local township schools. The busy ICDL testing centre at
iThemba LABS ran very well with more than 1 000 tests completed during the review period, and with only a
single test software failure. The pass rate for the first teacher group in 2008 was an outstanding 99%, the best
ever. Staff training included the customary annual ICDL course, basic computer literacy, a thesis template
workshop and Excel advanced training. Automated assessment software was developed for local use, and also
for use in schools to augment basic computer training.
The library staff managed the organization and logistics for numerous conferences and meetings during the year,
including
1.
Esteq Product training, July 2008,
2.
Women‟s Day event, August 2008,
3.
International Centre for Science and High Technology (ICS) workshop on Nanotechnology Regional
Networking, August 2008,
4.
iThemba LABS 20-year celebration symposium, November 2008, and
5.
CERN-SA launch, December 2008.
43
Document delivery remains one of the major core functions of iThemba LABS‟ library and information systems
service. There was a 7% increase in requests received during the review period. Information is sourced from
libraries across South Africa as well as from the British Library.
The ex-Schonland laboratory book collection was moved to the iThemba LABS (Gauteng) library from the
Witwatersrand University library in mid-2008. Additional shelving was installed, and electronic lists of the material
were provided by the WITS library for editing and importing into the iThemba LABS library database. The
material has been marked, accessioned and bar coded.
44
Safety, Health and Environmental Group
1.8 Safety, Health and Environmental Management
1.8.1 Highlights 2008/2009

iThemba LABS received an IRCA five-Star Rating Legal Compliance for 2008/2009. This is the fourth
consecutive year that iThemba LABS has received a five-star rating. The Audit also provided a gap
analysis with regards to the implementation of ISO 9001, ISO 14001 and OHSAS 18001 (Occupational
Health and Safety Assessment Series 18001).

iThemba LABS had its two-yearly Occupational Hygiene Survey, where all Occupational Hygiene Risk
Factors such as noise levels, asbestos and lead exposure, luminance quality in the work place, ventilation
and work with hazardous chemical substances were assessed by an Approved Inspection Authority.
Results show a slight improvement in Engineering Safety initiatives, compared with the results of two
years ago.

In 2008 a first aiders competition was initiated at the International Aids Day Celebrations.

The SHE Department has also initiated the OHSAS 18001 and strives to gain accreditation by
December 2009. IRCA is assisting with the implementation process.
1.8.2 Safety Management
Safety, Health And Environmental Committee
A new SHE Committee Chairperson, Dr Ricky Smit, was appointed after Dr Piet Cilliers had stepped down due to
his retirement. Three new SHE Representatives have joined the SHE Committee in 2008. The SHE Committee
has initiated SHE Committee Safety Walkthroughs to replace the Management Safety Walkthrough. The
walkthroughs will take place every month, during which the SHE Department, SHE Committee Chairperson and
the SHE Representative of the chosen area will do a thorough assessment. Three areas have been inspected
thus far. A total of 164 SHE non-conformances throughout iThemba LABS were discussed by the Committee. A
breakdown per Department is tabulated below:
Department
A-Block
B-Block
MRG
P & C-Block
S-Block
J-Block
G-Block
D & N-Block
F-Block
General
Totals
APR 08
0
0
0
0
1
1
0
0
0
1
3
MAY
2
3
0
6
0
0
2
0
0
0
13
JUN
2
0
6
0
0
0
0
0
0
0
8
JUL
0
0
5
0
0
4
0
8
0
0
17
AUG
1
0
1
0
0
2
0
1
1
0
6
SEP
0
0
3
0
0
4
0
6
2
0
15
45
OCT
2
0
9
0
0
5
0
1
0
1
18
NOV
3
0
4
1
0
0
0
0
1
0
9
DEC
2
0
4
0
0
0
0
0
0
0
6
JAN 09
0
0
2
1
0
5
0
0
1
1
10
FEB
2
0
0
0
0
0
0
5
1
1
9
MAR
0
0
45
0
4
0
0
0
0
1
50
Hazardous Material Substance Control
Removal of hazardous materials from D- and N-Block laboratories, Materials Research laboratories and the
Hospital has continued without incident. BCL Medical Waste has been assigned to assist with the removal of
medical waste from the Hospital and D- and N-Block on a monthly basis. Safe removal certificates are received
regularly.
All hazardous materials removed from laboratories and workshops are placed in the F-Block
hazardous chemical store for safekeeping until it is removed by an approved service provider for disposal. The
enforced control on hazardous waste accumulation in work areas has created increased HazMat safety amongst
laboratory and workshop staff.
Fire Prevention And Disaster Management
Annual Maintenance of all fire fighting equipment took place as usual from November 2008 to January 2009.
This selected time period was during shutdown as this allowed the service provider, Eagle Fire Safety, to access
the vaults to retrieve and service all fire extinguishers. There were no fire threats at or to the boundaries of
iThemba LABS during 2008/2009. TSS assists the SHE Department by maintaining the fire breaks on the
boundary fence on a regular basis. A new Fire Control Panel system which controls all the emergency alarms
and smoke detectors has been installed in August 2008.
First Aid
A total of 26 first aiders have been trained and appointed as per the requirements of the Occupational Health and
Safety Act, no. 85 of 1993. Ten first aiders have been trained to Level 2 while the remaining 16 Level 1 first
aiders will be trained to Level 2 upon renewal of their certification in 2010. Attendance of first aiders monthly
update training sessions have improved dramatically with a minimum of 10 first aiders attending each session.
The update training courses are hosted by the Occupational Health Clinic.
Occupational Injuries

Disabling Injuries
The DIFR, an internationally accepted formula to calculate disabling injury frequency levels, is used to assess the
disabling injuries: DIFR = Disabling Injuries X 200 000 / Work Hours. No Disabling Injuries occurred during this
period, thus the DIFR for 2008/2009 is zero.
46

Serious / Non-Disabling And Minor Injuries
The MIFR, a formula to calculate the minor injury frequency levels, is used to assess our minor injuries: MIFR =
Minor Injuries X 200 000 / Work Hours. Nine serious / non-disabling injuries and minor injuries occurred during
this period, giving a MIFR of 0.26 for 2008/09.
1.8.3 Occupational Health And Hygiene
Occupational Health
The Occupational Health Clinic in collaboration with the SHE Department continued to have monthly first aid
update and training sessions throughout the year. All injuries attended to by the Occupational Health Clinic are
progressed by the SHE Department for investigation.
Occupational Hygiene
As per the report of the Occupational Hygiene survey conducted by an Approved Inspection Authority in
2008/2009, all non-conformances are being attended to and the interventions discussed at the SHE Committee
Meetings.
1.8.4 Environmental Management
Water Sampling
Drinking water samples are collected once a month throughout iThemba LABS as per the requirements of
SABS/SANS 241, which prescribes the requirements for sampling and analysis of drinking water quality. The
results throughout the year have indicated that drinking water at iThemba LABS is well within legal limits. Water
samples from environmental sources are also collected as a comparison towards drinking water samples.
Waste Management
1000 Litres of oil was collected by the R.O.S.E. (Recycling Oil Saves the Environment) Foundation during May
2008.
BCL Medical Waste has been collecting iThemba LABS Medical Waste for proper disposal and
incineration throughout the Year. Interwaste collects the general waste once a week from the two general waste
skips situated behind F-Block and Materials Research. A new waste collection area was set up behind Materials
47
Research on request from the SHE Committee after continued reports of waste being blown around the general
grounds.
1.8.5 Loss Control Management
Insurance Claims And Loss Management
Total claims processed were as follows:
Motor-Vehicle Accidents
Theft / Break-in
Property Damage
Totals
2005
1
0
0
1
2006
3
0
1
4
2007
5
9
4
18
2008
4
3
0
7
Totals
13
12
5
30
Three theft incidents were reported and closed during 2008. Two incidents involved stolen laptops and one
incident was a break-in at Materials Research where computer equipment was stolen. Four motor vehicle
accidents were reported and closed during 2008/2009. Two incidents were in Cape Town (company owned
vehicles) and two were in Gauteng (rented vehicles). One motor vehicle accident involving an international visitor
using a company vehicle occurred on-site. Awaiting finalization of claim.
Security Management
A security plan is in place which requires a security presence 24 hours a day, seven days a week. Access /
egress control at the main-gate and security of all the buildings and the site at large are the major functions
carried out by Security personnel. A new Access Control system which uses the Biometric Data system i.e. finger
print scanning has been installed at the Security Main Gate. An armed response company has been contracted
to assist with security emergencies as they arise.
1.8.6 Quality Management Systems
The assembly of the SHEQ Manual is an on-going process. The policies, procedures and standards for all
activities are revised on a regular basis and incorporated into the manual. Documentation is continually
converted to be in-line with ISO 9001 and OHSAS 18001 requirements.
1.8.7 Training
Safety, Health and Environmental Management training for staff, students, visitors and users in 2008/2009 were
as follows:
COURSE
Staff Occupational Health Induction Training
First Aid Update Training
Level 2 First Aid Training
Protection and Prevention of Nuclear Facilities: Insider Threats
Team Fire Fighting Training
Substance Abuse Policy Awareness Training
SHE Representative Awareness Training
Security Induction Training
Evacuation Marshal Training
48
NO. OF ATTENDEES
42
66
10
4
10
All Staff Members
12
2
4
NO. OF SESSIONS
5
5
1
1
1
2
2
1
1
1.8.8 Housekeeping Management
During the period 2008/2009, the SHE Department continued to oversee the Health and Hygiene contracts for
deep cleaning all the cloakrooms on site, pest control of all areas including key buildings such as D and N-Block
and provision of plants for foyers, offices and boardrooms. Hygiene Contract revision discussions resulted in a
R50k annual saving and a promise of improved service delivery. The Housekeeping Services remain an in-house
service with some nine personnel employed, including a Supervisor.
1.8.9 Radiation Protection
Medicals Up To Date
To be a qualified radiation worker a person must have an annual medical, plus or minus three months. During
this year a concerted effort by the Radiation Protection Division, INCON Medical Services and all the Group
Secretaries resulted in zero anomalies. This is a major achievement when considering the number of travelling
scientists, occasional students and visitors that frequent the iThemba LABS site.
Low-Dose Maintenance of Vertical Beam Target Station
The Vertical Beam Target Station (VBTS) is a critical part of the Radionuclide Production facility at iThemba
LABS. Due to high beam intensity and long periods of bombardment the VBTS is subject to enormous levels of
neutron irradiation. The VBTS is subsequently the most radioactive component at iThemba LABS and a
complete maintenance overhaul was required during the year. Initial radiation measurements indicated a
projected total man-dose in excess of 10 milli-Sieverts. Training of the individuals performing the work, proper
planning and good Radiation Protection practices resulted in a total dose of less than 4 milli-Sieverts.
Upgrade of D Block Ventilation
The ventilation system in D Block is a critical part of the Radiation Protection Programme as it ensures that all
radioactive gases and particles are removed from the areas where personnel must work. Several anomalies
were spotted during the year and it was decided that the system should be upgraded. In January 2009 the
upgrade was approved and work commenced. It is expected the system will be fully operational by end June
2009.
Upgrade of Liquid Effluent System
All the radioactive liquid effluent generated in the production of nuclear medicines is controlled, monitored and
eventually released to the on-site dam by the Radiation Protection Division. The increase in demand for the
products of the Radionuclide Production Group has resulted in increased effluent. The liquid effluent system was
upgraded in 2008 to cope with this increase and we have seen a significant reduction in the radioactive content of
the liquid effluent. These results will have a beneficial effect on our Environmental Programme and subsequent
Public Dose calculations.
49
Assistance For External Companies

Leak Test Service
In terms of Article 3A of the Hazardous Substances Act of 1973, holders of radioactive sources must have their
radioactive source leak-tested annually. This is to ensure the radioactive source is not damaged or leaking and
causing a potential threat to the users or the public.
The Radiation Protection Division of iThemba LABS provides a leak-test service for all radioactive source holders
in the Western Cape. During the period April 2008 to March 2009 iThemba LABS performed 162 leak tests and
generated 162 leak-test certificates. To ensure responsible disposal of old radioactive sources, Radiation
Protection Division has taken ownership of several small sources which will be absorbed into our radioactive
waste programme.

Distell Pty Ltd.
Distell uses radioactive sources to ensure all their bottles contain the correct amount of liquid. The bottling plant
at Epping as well as the main plant in Springs has recently upgraded their facility and needed to import machinery
incorporating radioactive sources from Germany. iThemba LABS assisted Distell with the ordering, importing and
installation of these units to ensure they are working in a safe and reliable manner.

Denel
Denel uses radioactive sources to ensure uniform thickness of materials used in their production plant. iThemba
LABS provided technical guidance and leak-test services for Denel.

SANS Fibres
SANS Fibres uses radioactive sources to monitor the tank levels for their products. These sources need to be
leak-tested on site as they are permanent fixtures. Two members of the Radiation Protection division spent a day
at SANS performing leak tests and dispensing general radiation protection principles.

Survey One
Survey One is a ship handlers company specialising in Hazardous Goods handling. For the last seven years,
Survey One have requested the services of an RPO to assist with the off-loading and shipping of radioactive
material. Survey One also provides a Leak Testing service for international vessels, using the iThemba LABS
Leak Testing Services.
Training Programme

RPO Training Programme
Companies that use radioactive material need to appoint a Radiation Protection Officer (RPO) who will be
responsible for the material and is a point of contact for the Department Of Health – Directorate Radiation
Control. During this year 14 companies have sent their RPO‟s to attend the Radiation Protection Training Course
at iThemba LABS. These courses are presented on the first Tuesday of each month and this year we have had
50
an impressive turn out with no less than 22 people attending the course from various companies, such as
De Beers Marine, XSIT, HEPRO, Infruitech, Distell and INCON.
In March 2009, 48 trainee radiographers from University of the Western Cape attended iThemba LABS' Radiation
Protection Training course. Their lecturer plans to schedule this training into all her future training sessions.
Links With Koeberg Nuclear Power Station
The two nuclear facilities in the Western Cape are iThemba LABS and Koeberg Nuclear Power Station. It is
important that the Radiation Protection departments from the two organisations stay in contact and are able to
provide assistance for each other. A series of training sessions was developed and presented to the Radiation
Protection Department at Koeberg to explain our function at iThemba LABS and how we can support and develop
each other, particularly in the field of emergency response. The courses were well received and discussions are
under way to expand on this idea.
In addition, Koeberg has an Environmental Survey Laboratory (ESL) that ensures the environment is not
adversely affected by Koeberg and is also intended to be used for post-accident sampling in the unlikely event of
a nuclear accident. A recent study showed that the ESL would probably become unusable in certain accident
scenarios so an alternative ESL needed to be identified. iThemba LABS has been identified as an ideal
candidate due to our location (70 km away on the opposite coast) and our ability to measure low level
radioactivity in our Environmental Radioactivity Laboratory.
Radioactive Waste Programme
The 20-year backlog of Radioactive Radwaste has been packaged into 210 steel drums according to the NECSA
Waste Acceptance Criteria and is now waiting for disposal. Several options for disposal are available and have
been investigated. A final decision will be reached in 2009 when we can start shipping the waste to an approved
radioactive waste repository.
The IAEA programme of removing all large unused radioactive sources and upgrading the security on the
remaining sources has reached a conclusion. iThemba LABS (Cape) identified a large Co-60 source that was no
longer needed and iThemba LABS (Gauteng) had a similar unit that could be disposed of. The two remaining
large Co-60 sources have had their security systems upgraded to conform with best international practices, as
specific by the IAEA.
iThemba LABS was also instrumental in assisting NECSA to collect and remove other sources from various
companies in and around Cape Town. A total of 19 sources were identified and collected on behalf of NECSA.
All the sources have been taken to an approved repository.
Radiation Exposure Of iThemba LABS Personnel
International guidelines have been developed to limit and control the amount of radiation that any individual
worker may be exposed to. At iThemba LABS all personnel who may be exposed to radiation during the course
of their employment are issued with a personal dosimeter. The doses accrued by these dosimeters are
monitored on a monthly basis to ensure nobody exceeds the recommended limits.
51
In addition, several members of staff work with small amounts of high-activity liquids, particularly during the
manufacture and dispensing of nuclear medicines. To ensure these members of staff are not exposed to
excessive hand-exposure they are issued with extremity dosimeters, usually worn on the finger. These are
monitored on a monthly basis to ensure nobody exceeds the recommended limits.
Radiation Protection Indicators

Highest Individual Dose
This graph displays the highest total body dose received by a member of staff in any single calendar month. The
high dose in September 2008 is due to maintenance on the Radionuclides Cooling System. The individual was
banned from radioactive work for the rest of the year, as he was likely to exceed the Administrative Limit of
12 mSv per annum. Any individual monthly dose above 4 mSv must be reported to the Regulator (DoH).

Worker Monthly Dose
This graph displays the total dose to all staff on a monthly basis. This is a good indicator of the overall success of
the Radiation Protection programme. The graph does not take into account the fluctuating number of radiation
workers, which has steadily increased during this period. The peak in May is due to the irradiation of the
dosimeters while in transit. The “twin peaks” in September and November were due to longer Wearing Periods
as the following Wearing Period badges were not available.
52

Liquid Effluent Releases
The quantity of radioactive effluent pumped to our on-site dam is strictly controlled and monitored by the
Radiation Protection Division. Our Department of Health license allows us to release 120 ALI‟s (Annual Limit of
Intake fractions) per annum into the sewerage system. We prefer to keep it on-site where it can be closely
monitored as part of our Environmental Programme.
53
Science and Technology Awareness Group
1.9 Science and Technology Awareness Programme
The CIT division has interacted with more than 15000 learners and 1500 educators over the past year though
interactive workshops and science shows. It participated in various science festivals both locally (Scifest,
Science Unlimited, SU science week, Mthatha-regional science festival) and internationally (Namibian science
week). The division has also participated in teacher development through interventions (nationally and provincial)
of the Department of Basic Education.
The division organized two very successful public lectures by international speakers (Walter Kutchera and Bikash
Sinha) at iThemba LABS in an attempt to expose the general public to the scientific discourse.
The division hosted two very successful interventions, namely Camp iTL‟09 and Girlz just wanna hav PHUN, in
collaboration with SAASTA.
Camp iTL’09 was an intervention aimed at exposing senior
students from local universities to the research activities at
iThemba LABS. The intervention also provided academics
from the three local universities the opportunity to highlight
the research activities associated with their institutions.
The intervention has highlighted the importance of
professionals at iThemba LABS
(and other National
Facilities) to get involved in communicating what they do on a
regular basis.
We need to pursue partnerships with
Students with Dr Rob Bark during Camp iTL.
institutions of higher learning in order to assist in the
promotion of Science and Technology on a bigger scale.
The Girlz just wanna hav PHUN event was a 3-day event and
was attended by female undergraduate students from the
universities of Limpopo, Western Cape, Cape Town,
Stellenbosch, Zululand, Witwatersrand and Nelson Mandela
Metropolitan. Accommodation for 30 students was arranged at
the Stellenbosch Lodge. A shuttle-service was provided for
students attending from the University of the Western Cape.
The average attendance for the whole week end was 40
Hellen Chuma with one of the presenters,
Mrs Elsabe Daneel.
students per day.
A number of staff members from iThemba LABS, academics from local universities, a winemaker from
Stellenbosch and a TV-personality participated in the programme.
The event, which aimed to not only promote science, but also address some of the stereotypes associated with
women in science, was an “educational feast” for the students.
54
2. SCIENTIFIC AND TECHNICAL REPORTS
55
2.1 Medical Radiation Group
2.1.1 Proton therapy clinical programme
Only three patients were treated on the 200 MeV horizontal beam proton therapy facility during the financial year
2008/09. The capability to treat more patients was restricted due to the suspension of the clinical programme
from January until April 2008 as a result of the energy crisis in the country. In an effort to alleviate the impact on
all activities, iThemba LABS reduced its energy consumption by voluntary load-shedding each Monday morning
and offering proton therapy only three days per month, excluding the shutdown months of July, December and
January.
1993 - 2009
April 07 - March 08
April 08 - March 09
Arteriovenous malformation
82
2
1
Angioma
15
Acoustic neuroma
65
3
1
Pituitary adenoma
63
Meningioma
41
Brain tumour
60
Brain metastasis
33
Paranasal sinus tumour
23
Skull base tumour
28
1
Orbital & eye tumour
33
3
Craniopharyngioma
14
Head & neck tumour
11
Prostate tumour
4
Other
31
Patient total
503
1
9
3
Table 1: Patients undergoing proton therapy, by diagnosis
Benign intracranial lesions treated with proton therapy
There are many risks associated with surgery for benign intracranial lesions. Radiotherapy is often used for
these lesions, particularly if surgery is incomplete or the lesion recurs post-surgery. Conventional photon
radiotherapy is often not suitable for these lesions due to the high dose to normal brain tissue and resulting late
effects of radiotherapy. This is particularly important if the lesion is close to critical structures such as the
brainstem or cranial nerves, or if one is treating a young patient with a good prognosis. Proton beam
radiotherapy is highly conformal with no dose distal to the proton range. Another significant advantage for proton
56
beam therapy is that the integral dose is approximately half that of photon therapy (H. Suit, Int. J. Rad. Oncol.
Biol., Phys. 2002). All of these factors make proton therapy ideal for benign intracranial lesions.
At iThemba LABS, with the proton beam available for clinical use on limited days, and with a fixed horizontal
beam line, proton therapy is only offered as a stereotactic radiosurgical modality. Treatment is administered by
means of a 200 MeV passively scattered beam with customized individual beam collimation. A non-invasive
stereophotogrammetric patient positioning and monitoring system utilizing markers on a mask, video cameras
and a computerized adjustable treatment chair is used. This non-invasive stereotactic positioning system makes
fractionation possible, and since the larger, complex shaped lesions are referred that are not suitable for LINACbased stereotactic radiosurgery, patients can then receive treatment in 1 to 3 fractions.
Until last year, patients were treated wearing a tight-fitting Perspex facemask. In an effort to improve the
accuracy of refitting, a bite block system was developed to decouple the localization system and the
immobilization. This new device consisted of a carbon fibre marker carrier coupled to a vacuum-assisted bite
block. A pilot study was performed to evaluate the accuracy and feasibility of this new system (1). The study was
approved by the Research and Ethics Committee of the University of Cape Town. The reseating accuracy of the
vacuum-assisted bite block proved to be superior to the refitting of the previously used facemask. Localising and
treating patients using the carbon fibre marker carrier in conjunction with the vacuum assisted bite block is
accurate and reproducible and the application of this method is simple, quick and reliable. All patients are now
treated using this new system.
Clinical results of proton therapy
A total of 500 patients have been treated to date in the programme which started in 1993. Of those, 82 patients
had arteriovenous malformation, 41 had meningioma and there were 63 with acoustic neuroma.
The results of patients who had proton radiosurgery for meningiomas, arteriovenous malformations and acoustic
neuroma were updated (2,3). Long-term results of stereotactic proton beam radiotherapy for acoustic neuromas
were also published in Ref. 4.
Arteriovenous Malformations
66 patients were analysed. The median age was 33 years with a male / female ratio of 1.4. The median
International Commission on Radiation Units and Measurement (ICRU) reference dose was 19.7 Single Fraction
Equivalent (SFE) CGyE (single-fraction equivalent cobalt Gray equivalent) with a mean minimum target dose of
17.2 SFE CGyE. The mean volume was 19.1 cm3 (1.7 – 64 cm3). With a mean follow-up time of 6.5 years, the
obliteration rate for target volumes smaller than 25 cm3 was 61,5% and 18% for volumes greater than 25 cm3.
30% of patients experienced a clinical improvement while 51% of them remained clinically stable.
Skull Base Meningiomas
34 patients were analysed. The median age was 52 years with a female to male ratio of 3 to 1. The median
ICRU reference dose was 17.9 SFE CGyE with a mean minimum target dose of 15 SFE CGyE. The median
57
tumour volume was 19.4 cm3 (2.6 – 79.8 cm3). With a mean follow-up time of 6.2 years, tumour control (defined
as absence of tumour growth) was achieved in 91% of patients with 55% demonstrating a clinical improvement.
Acoustic Neuromas
51 patients were analysed. The mean age was 50 years with a female to male ratio of 1.2. The mean ICRU
reference dose was 16.1 SFE CGyE with a mean minimum target dose of 13.3 SFE CGyE. The mean target
volume was 5.9 cm3 (0.2 – 45.7 cm3). With a mean follow-up time of six years, a 98% five-year radiological local
control was observed. Hearing preservation was achieved in 42% of patients while 90% of patients had facial
nerve preservation.
Conclusion
Proton radiosurgery is a suitable treatment modality for large inoperable lesions requiring radiosurgery.
References
1. M Loubser, J Symons, C Trauernicht, S de Canha, J Parkes, F Vernimmen. 14th National Congress of the
South African Society of Clinical & Radiation Oncology, CTICC, Cape Town, 19 – 22 February 2009.
2. F J A I Vernimmen. 14th National Congress of the South African Society of Clinical & Radiation Oncology,
CTICC, Cape Town, 19 – 22 February 2009.
3. F J A I Vernimmen. 1st Romanian Society of Hadron Therapy Workshop, Predeal, Romania, 27 February –
1 March 2009.
4. F J A I Vernimmen, Z Mohamed, J P Slabbert, J Wilson. Radiotherapy and Oncology 90 (2009) 208-212.
58
2.1.2 Neutron therapy clinical programme
Neutrons are produced at the cyclotron by the reaction of 66 MeV protons on a beryllium target. The beam is
collimated and further shaped, initially by tungsten blocks and subsequently by a multiblade trimmer. The beam
characteristics are similar to those of an 8 MV X-ray beam. The advantage of neutron therapy is in its biological
effects. Tumour cells in the resting phase of the cell cycle (G0) are less sensitive to photons, whereas with
neutron therapy there is less variation in sensitivity in the different phases of the cell cycle. Therefore neutron
therapy would be the preferred treatment for slowly growing tumours. 65 patients were treated on the isocentric
neutron unit during the year.
Head & Neck carcinoma
Salivary gland carcinoma
Soft tissue sarcoma
Breast carcinoma
Cervical carcinoma
Bronchus carcinoma
Uterine sarcoma
Mesothelioma
Paranasal sinus carcinoma
Bone sarcoma
Malignant Melanoma
Other
Patient total
1988 - 2009
217
521
134
293
5
6
94
21
65
111
67
55
1589
April 07 - March 08
3
16
4
32
April 08 - March 09
6
22
3
27
1
3
1
2
1
3
59
65
Table 1: Patients undergoing neutron therapy, by diagnosis
Clinical results of neutron therapy
The results of patients who had neutron radiotherapy for salivary gland tumours were updated [1], and the
findings of neutron therapy for advanced breast cancer, uterine sarcoma, irresectable neck nodes, maxillary sinus
tumours and sacral chordomas were also recently presented [2].
Salivary Gland Tumours
From 1989 until 2004, 446 patients with tumours of the major or minor salivary glands were treated, 350 with
radical intent. Of these 107 had macroscopic residual disease left after surgery; 60 tumours were not resected
because of anticipated surgical morbidity, and 179 tumours were irresectable. Over 50% were T4 tumours (197).
They received 20.4 neutron Gy in 12 or 15 fractions over four or five weeks.
The five- and ten-year overall local control probabilities were 54% and 43% respectively, and five- and ten-year
survival rates were 70% and 60% respectively. Local control and survival probability at ten years were 71% and
79% for those with macroscopic residual disease after surgery, 37% and 72% for those with unresected tumours,
and 15% and 34% for irresectable tumours. Local control at ten years was 100% for T1, 60% for T2, 39% for T3
and 30% for T4 tumours. Local control probability at five years was 72% for low-grade malignancies and 46% for
59
high-grade malignancies; and the ten-year survival rates were 80% and 57% respectively. There was no
difference whether the initial tumour or recurrent tumour was treated.
From these findings, neutron therapy appears to be the treatment of choice for salivary gland tumours with
macroscopic residual disease after surgery and for irresectable tumours.
The improved local control is
associated with improved survival rates for these advanced tumours.
Inoperable Breast Cancer
Patients with locally advanced breast cancer were treated in a prospective randomised dose-seeking study in the
early 1990‟s comparing 17 Gy neutrons with 19 Gy, both in 12 fractions over four weeks. Local control rate
(complete and partial response rates – CR & PR) for the 74 patients was 68% for 17 Gy and 83% for the 19 Gy
arm. There was no difference in survival or acute toxicity but there were three grade 4 toxicities with the higher
dose. The shorter course of four weeks was well tolerated with apparent improved quality of life.
From 1996 to 1999 a controlled trial of 18 Gy neutron therapy in four weeks was compared with a six-week
course of 60 Gy photon therapy. 22 of 27 patients were evaluable and the local control (CR & PR) was 50% for
the neutron arm and 60% for the photon arm. Median survival was 21,5% for neutron therapy and 13% for the
photon arm. Again the shorter course of four weeks for neutron therapy was better tolerated than the photon
arm, with improved quality of life.
Uterine Sarcomas
37 patients with uterine sarcoma were treated with neutron therapy, 18 – 20 Gy in five weeks. Seven patients
with completely resected tumours had an 83% three-year local control and survival; 14 patients with incompletely
resected tumours had a 45% three-year local control and 33% three-year survival; and of the 15 patients with
irresectable tumours there were 2 PR and a 19% two-year survival. Four patients with incompletely resected
tumours were locally clear when they died of metastases at 7-37 months.
Maxillary Antrum Tumours
There were 91 patients with maxillary antrum tumours treated with a median dose of 20 Gy in 12 - 15 fractions in
four to five weeks. 80 patients had T4 tumours and 11 had T3. Fifty were squamous carcinomas and the
remainder were salivary gland malignancies. The local control rate at two years was 60% for salivary gland
tumours, 30% for squamous carcinomas and 45% overall. Survival at two years was 80% for salivary gland
tumours, 35% for squamous carcinomas and 57% overall.
These results compare favourably with other neutron therapy series but chemoradiation is showing promising
results.
Irresectable Cervical Squamous Carcinoma Lymphadenopathy
Several trials of neutron therapy for squamous carcinoma of the head and neck showed varying results but one
demonstrated improved local control for neck nodes. Twenty patients were treated with irresectable neck nodes
from an unknown or small primary, with 20 Gy neutron therapy in 12 - 15 fractions in four to five weeks. The
60
median diameter was 8.5 cm. There were 8 CR and 6 PR. The median survival was 25 months (range 3 - 91
months) in the eight patients achieving a CR, and 5.5 months (range 3 – 16 months) in the other 12 patients.
Outcomes and toxicity do appear to be acceptable, with the added benefit that the dose is delivered in a relatively
short time.
Chordoma
19 patients were treated with neutron therapy: median dose 18 Gy in four weeks. Of these patients, 15 were
evaluable. Patients experienced a median time to clinical improvement of 7.5 months (range 2 – 20.5 months)
and the median duration of clinical response was 36 months (range 4 – 89 months). Patients had a 63% fiveyear survival which is comparable to the only other neutron therapy series, but carbon radiotherapy is showing
promising results.
References
1. C E Stannard, F Vernimmen, D Jones, E de Kock, E Mills, V Levin, S Fredericks, J Hille, A Hunter.
1st Romanian Society of Hadron Therapy Workshop, Predeal, Romania, 27 February – 1 March 2009.
2. C E Stannard, E Murray, L van Wijk, M Maurel, P Kraus, F Vernimmen, S Fredericks, S de Canha.
1st Romanian Society of Hadron Therapy Workshop, Predeal, Romania, 27 February – 1 March 2009.
61
2.1.3 Monte Carlo simulations
M W Swanepoel, J Mbewe
Comparison of MCNPX, GEANT4, and real measurements of Coulombic scattering
During 2008 research continued concerning the differences between proton dose distributions measured in a
water phantom for scattering foils of different thicknesses and atomic numbers over a range of beam energies,
and GEANT4 [1] and MCNPX [2,3] simulated distributions. It is hoped that the work will allow GEANT4 and
MCNPX to be selected appropriately for simulations, and that differences between simulated and measured dose
distributions can be explained in terms of the different Coulombic scattering and range straggling models of
MCNPX and GEANT4. Final experiments were completed, and a GEANT4 simulation [4] was adapted for
modelling the experiment. First attempts were also made to simulate the experiments using MCNPX. Work on
this project is ongoing.
MCNPX simulations of the mouse gut experiments of Dr Kobus Slabbert and Professor John Gueulette
Depth-related changes in Relative Biological Effectiveness (RBE) along 7 and 5 cm proton Spread-out Bragg
Peaks (SOBPs) created by stepped Perspex range modulating propellers were investigated by J Gueulette, et al.
[5,6]. In one set of experiments the jejunal intestines of mice were drawn down through abdominal slits and
immersed in a saline-filled gap in a Perspex phantom, such that the proton beam passed through a length of
jejunum disposed laterally across the proton beam‟s axis. Comparison of the numbers of regenerated crypt cells
present at set intervals after irradiation with those regenerated after 60Co -irradiation, yielded an RBE at the
distal edge of a 5 cm long proton SOBP that was 10% greater than at its centre [6]. Physical aspects of the
absorbed dose distributions in murine jejunal specimens at proximal, central, and distal positions of 5 and 7 cm
SOBPs were modelled by means of MCNPX v2.7a simulations. It was found that while 30% of the dose in the
distal SOBP position of a 5 cm SOBP was delivered at a Linear Energy Transfer (LET) > 5 eV/nm, just 10% of the
dose delivered to central specimens was delivered at a LET > 5 eV/nm, and mean blade step LETs for the
proximal specimen did not exceed 3 eV/nm. Similar results occurred for the 7 cm SOBP. Careful consideration
of the density of proton tracks led to the conclusion that dose rate effects could not account for the observed axial
increases in the RBE. Thus it was concluded that these increases were most likely related to the mean LET at
which the dose was delivered for each propeller blade step.
References
1. S Agostinelli et al. GEANT4 – A simulation toolkit. Nuclear Instruments and Methods in Physics Research A,
506 (2003) 250-303.
2. J F Briesmeister. MCNP: A general Monte Carlo N-Particle Transport Code. Los Alamos National Laboratory
Report LA-13709. (2000).
3. M B Chadwick, P G Young, S Chiba, S C Frankle, G M Hale, H G Hughes, A J Koning, R C Little,
R E MacFarlane, R E Prael, L S Waters. Nuclear Science and Engineering 131 No. 3 (1999) 293.
4. G A P Cirrone. GEANT4 simulation of an ocular proton therapy beam line. International Conference on
Advanced Technology and Particle Physics; Como, Italy; 6–11 Oct 2003.
5. J Gueulette, L Böhm, J P Slabbert, B M de Coster, G S Rutherfoord, A Ruifrok, M Octave-Prignot, P J Binns,
A N Schreuder, J E Symons, P Scalliet and D T L Jones. Int. J. Rad. Oncol. Biol. Phys. 47 (2000) 10511058.
6. J Gueulette, J P Slabbert, J Martinez, B M de Coster, D T L Jones, and A Wambersie. Variation of the proton
RBE in the SOBP shown with in-vivo systems. Protons, Ions and Neutrons in Radiation Oncology
International Symposium, Munich, Germany, July 6-7, 2007.
62
2.1.4 Treatment planning system
E A de Kock
The treatment planning system used for radiotherapy at iThemba LABS consists of a collection of programs, of
which the VIRTUOS system and the dose calculation module are the two principal components. VIRTUOS is a
graphical front-end that acts as a general-purpose, virtual radiotherapy simulator [1]. It is developed, tested and
maintained by the Deutsches Krebsforschungszentrum (DKFZ) in Heidelberg, Germany. The rest of the
treatment planning system software is developed and maintained in-house.
The latest release of VIRTUOS is available for both Microsoft Windows and Linux-based PC platforms. It
provides a rich and powerful set of functions, including DICOM and DICOM-RT import and export facilities, image
fusion, segmentation of anatomical structures, setting of the parameters that define the treatment fields, and
displaying the dose distributions and dose statistics. However, it needs to be supplemented with an external
dose calculation module before it can be used as a full-blown, modern treatment planning system.
The iThemba LABS dose calculation module supports the calculation of the three-dimensional dose distributions
for both proton and neutron [2] therapy beams. This software is ideally suited for radiotherapy planning at
iThemba LABS since it incorporates aspects specific to the iThemba LABS treatment units and produces auxiliary
output, such as a detailed treatment and dosimetry report, as well as customized treatment files for the therapy
control and patient positioning systems. Other components of the treatment planning system include programs to
generate the system files that contain the CT-calibration curves [3,4], beam data and dose model data [2] needed
by the dose calculation module.
The treatment planning system currently commissioned for clinical use at iThemba LABS is based on version
3.0.0 of VIRTUOS, which only runs on OpenVMS platforms. This old version does not support image fusion, nor
does it provide any means to import DICOM images or DICOM-RT objects. These serious deficiencies of the old
treatment planning system, combined with the old age of the OpenVMS workstations, necessitated an update of
the iThemba LABS software so that it could be integrated with latest release (version 4.6.7) of VIRTUOS. The
upgrading of the iThemba LABS software was started in June 2006 and was completed in December 2008. This
process involved the following tasks:
 Development and implementation of new parser routines to handle the latest formats of the patient and planspecific files being used by VIRTUOS. Many other software changes were required to accommodate the new
coordinate systems that were introduced to describe the data in these files.
 Proper integration of the neutron and proton dose engines into a single dose calculation module (they were
implemented as separate dose calculation programs in the old treatment planning system).
 Incorporation of a new strategy for the segmentation of treatment objects attached to the patient, such as the
bite-block and marker carrier system [5] used for proton therapy. This strategy was introduced to reduce the
memory demands on VIRTUOS and to ensure that the effects of such treatment objects are correctly handled
in the dose calculations.
63
 New features were added, such as the support for multiple target volumes and the use of highly asymmetrical
fields.
 A new and much more efficient ray-tracing algorithm [6] was implemented in the dose engines. This algorithm
accommodates the new segmentation scheme and the support for multiple target volumes.
 Many of the more time consuming dose calculation routines were modified and parallelized with OpenMP
directives, which considerably increased their efficiency on multi-core processors.
 The dose distributions for intermediate plans may now be calculated on down-sampled CT cubes, thereby
decreasing the computation times even further.
 A comprehensive checksum system has been developed and incorporated in the software that generates the
system files. This allows the dose calculation module to verify the integrity of those system files that are used
during the dose calculations.
 An access control system has been developed to allow different levels of access to the different treatment
planning system programs. For example, while all the authorized clinicians, radiographers and medical
physicists may use VIRTUOS and the dose calculation module, only the medical physicists are allowed to use
the programs that generate the system files.
 The software module that prepares the treatment data for the proton patient positioning system was modified
to allow the CT-scanner coordinates of all the markers on the marker carrier [5] to be calculated by registering
the measured coordinates of a subset of the markers against the accurately surveyed coordinates of the
markers. A random sample consensus (RANSAC) algorithm [7] is used to reject markers with poorly
measured coordinates. This program significantly reduces the amount of manual effort required to obtain the
CT-scanner coordinates of the markers and helps to eliminate measurement errors.
 The software module that generates the CT calibration data for the dose calculation engines was modified to
produce additional calibration data for a new DRR program. This program, written by Helge Reikerås (a
visiting student from Norway), is used to generate the digitally reconstructed radiographs (DRR's) needed to
assist in the verification of the proton therapy treatment setups.
 An administrative module was introduced to simplify all the different planning tasks, such as the dose
calculations for a single plan, combining of multiple plans into a single plan, generating and printing of plan
reports, and generating input files for the therapy control and patient positioning systems.
The new treatment planning system software has been installed on two Windows-based workstations, both using
the Samba server on the radiotherapy network for the storage and sharing of patient data on a RAID storage
system. The server is equipped with a tape-drive that allows for the automatic backup of all the patient data on a
daily basis.
Two supplementary programs were developed and commissioned that allow the planning data to be exported
from the new to the old treatment planning system, so that a plan can be calculated on both systems and then be
compared. This allows the bulk of the planning to be done on the new system, while only the final treatment plan
64
for a patient is recalculated on the old treatment planning system. This scheme allows the clinical users to benefit
from the new treatment planning system even though it has not yet been fully commissioned, and helps to speed
up the stress testing of the new dose calculation module (over 200 neutron and 130 proton plans have been
calculated without any run-time errors on the new system since February 2009).
Good progress has been made with the development of a program that will allow dose profiles to be extracted
from the dose cube of a treatment plan and to compare automatically the extracted profiles against measured
data. The differences between the computed and measured dose distributions will be quantified in terms of the
widely accepted  dose comparison index [8]. This tool is essential for the proper and final testing of the new
treatment planning system.
References
1. R Bendl, J Pross, W Schlegel, Proceedings of the International Symposium CAR 93, Computer Assisted
Radiology. eds. H U Lemke , K Inamura, C C Jaffe, R Felix, Springer (1993) 676 – 682, 822 – 823.
2. E A de Kock, Radiation Physics and Chemistry, 71 (2004) 967 – 968.
3. U Schneider, E Pedroni and A Lomax, Physics in Medicine and Biology, 41 (1996) 111 – 124.
4. E A de Kock, “Program CT_CALIBRATE: CT calibration curves for proton radiotherapy planning”, iThemba
LABS Report, 30 June 2003.
5. M Loubser, J Symons, C Trauernicht, S De Canha, J Parkes , F V Vernimmen , “A carbon fiber marker carrier
coupled to a bite block for use in proton beam stereotactic radiosurgery”, Poster and oral presentation,
Fourteenth National Congress: SA Society of Clinical and Radiation Oncology (SASCRO) and SA Society of
Medical Oncology (SASMO), Cape Town, 19-22 February 2009.
6. F Jacobs, E Sundermann, B de Sutter, M Christiaens and I Lemahieu, Journal of computing and information
technology, 6 (1998) 89 – 94.
7. M Fischler and R Bolles, Commun. Assoc. Comp. Mach., 24 (1981) 381 – 395.
8. T Ju, T Simpson, J O Deasy and D A Low, Medical Physics, 35 (2008) 879 – 887.
2.1.5 Real-time range controlling system
M W Swanepoel, E A de Kock
Currently the range of the proton beam is checked by means of an axially-retractable set of annular parallel-plate
ionization chambers. When this device is pushed downstream to its active position, the core of the proton beam
passes through the hole of the ionization chambers, while its periphery passes through the active part of
chambers, so allowing the beam‟s range to be determined. However, the device must be retracted upstream
during treatment so that it does not interfere with the spatial properties of the beam, thus disabling the device
from measuring the beam‟s range. The replacement of this system by a fully automated, real-time range control
system is therefore desirable.
Monte Carlo simulations conducted during 2007 and 2008 demonstrated that the existing occluding ring of the
proton scattering system can be replaced by an annular multilayer Faraday cup. The designs of this multilayer
Faraday cup and the vacuum chamber to house it were refined to produce an optimal combination of measurable
ranges and resolution, proton fluence distributions, manufacturing technique and cost. The proposed design of
the new range controlling system is shown in Figure 1.
65
Figure 1: Proposed design of the new range controlling system
A set of thin radial wires will conduct the charges collected on the multilayer Faraday cup plates to the inner
surface of the vacuum chamber, where the wires will be gathered and connected to an airtight multi-pin socket. A
multi-core cable connected to this socket will conduct the charges to the range monitoring unit, now under
development at the Korean Institute of Radiological and Medical Sciences (KIRAMS). This unit will calculate the
beam range from the charges integrated over each revolution of the range modulating propeller, thereby allowing
the control computer of the double-wedge energy degrader to adjust the proton beam‟s range as required, once
during each revolution of the propeller. One of the new ETX computer modules will be utilized to upgrade the
existing control system for the energy degrader.
66
2.2 Radionuclide Production
2.2.1 Investigation of the 68Zn(p,2p)67Cu nuclear reaction: New measurements and
compilation up to 100 MeV
F Szelecsényi1, G F Steyn2, S G Dolley2, Z Kovács1, C Vermeulen2 and T N van der Walt3
1 Cyclotron
Department, ATOMKI, H-4026, Bem tér 18/C, Debrecen, Hungary
iThemba Laboratory for Accelerator Based Sciences, PO Box 722, Somerset West, 7129, South Africa
3 Department. of Chemistry, Cape Peninsula University of Technology, PO Box 1906, Bellville, 7535, South Africa
2
The excitation function was measured for the 68Zn(p,2p)67Cu reaction from its threshold energy up to 40 MeV.
This was done in order to clear up large discrepancies in the available data in the literature and to quantify the
67Cu
content which would be present in 61Cu and 64Cu productions (both of which have PET potential) where it
appears as a longer-lived radio-contaminant. In recent years, 67Cu (T1/2 = 61.8 h) has also become increasingly
important as a radioisotope for internal radiotherapy.
After irradiation, the radio-copper isotopes were
quantitatively separated from the highly enriched 68Zn (> 98%) metal foils. Two sources were prepared from each
foil in the foil stack, namely by sealing a volumetrically accurate fraction of the final eluate in a standard 10 ml
counting vial and by making a point source by evaporating the remaining fraction to dryness in a specially
designed Teflon backing having a conical cavity. The point sources were required to check the calculation of selfabsorption factors for the extended sources as the strongest gamma-line in 67Cu decay is only 184.58 keV
(48,8%). The counting time of each source varied between 1 and 3 hours and the results from the two sets of
sources were in good agreement. A recommended excitation curve was also compiled up to 100 MeV based on
an evaluation of all the available data sets. The results are shown in Figure 1.
References
F Szelecsényi, G F Steyn, S G Dolley, Z Kovács, C Vermeulen and T N van der Walt, Nucl. Instrum. and
Meth. B (2009) in press; available online, doi:10.1016/j.nimb.2009.03.097.
14
68
12
Cross-section (mb)
1.
67
Zn(p,2p) Cu
10
8
Bonardi et al.(2005) [2]
Cohen et al.(1955) [3]
Levkovskij (1991) [4] (corrected)
McGee et al.(1970) [5] corrected)
Morrison & Caretto (1964) [6]
Stoll et al.(2002) [7]
This work
Recommended curve (this work)
6
4
2
0
0
20
40
60
80
100
Proton energy (MeV)
Figure 1: Cross sections of the 68Zn(p,2p)67Cu nuclear reaction, including the recommended values.
The references to previously published work can be found in Ref. 1.
67
2.2.2 Investigation of the production feasibility of 186Re via the 192Os(p,3n)186Re
nuclear reaction
F Szelecsényi1, G F Steyn2, S G Dolley2, K Aardaneh, C Vermeulen2 and T N van der Walt3
1 Cyclotron
Department, ATOMKI, H-4026, Bem tér 18/C, Debrecen, Hungary
3 Department of Chemistry, Cape Peninsula University of Technology, PO Box 1906, Bellville, 7535, South Africa
2
Rhenium-186 is being regarded as an ideal radionuclide for radio-immunotherapy because of its suitable decay
properties (E-max = 1.07 MeV, - = 92,53%, T1/2 = 3.7183 d). Thus far the 186W(p,n)186Re and the 186W(d,2n)186Re
nuclear reactions were studied in detail [1] for the no-carrier-added production with accelerated charged particles.
Since tungsten is not a mono-isotopic element (the amount of 186W in natural tungsten is only 28,6%) for practical
productions both methods require highly enriched (>99%)
186W
target material to decrease the yields of the
longer-lived undesirable rhenium radio-contaminants, i.e.
182Re
(T1/2 = 64 h),
183Re
(T1/2 = 70 d),
184mRe
(T1/2 = 169 d), and 184gRe (T1/2 = 38 d) [1]. Even if 100% enriched 186W material is used, the formation of 184Re via
the
186W(p,3n)184Re
[Ethr = 15.3 MeV] and the
186W(d,4n)184Re
[Ethr = 17.6 MeV] reactions limits the „useful‟
production energy windows from the relevant thresholds up to 15.3 and 17.6 MeV, respectively [2]. An additional
disadvantage of the „deuteron method‟ is the very limited access to accelerators that produce deuteron beams.
In this work, we considered an alternative production method based on the
192Os(p,3n)186Re
nuclear reaction.
One of the reasons for this study was to investigate the feasibility of 186Re production with proton beams of higher
energy, which are routinely available at iThemba LABS for its radionuclide production programme.
Experimentally measured cross-sections were presented for the first time [2] for the
reaction up to 66 MeV. Highly enriched thin
192Os
192Os(p,3n)186Re
nuclear
targets (15 pcs), prepared by electro-deposition onto Cu
backings at iThemba LABS, were irradiated with an external proton beam delivered by the SSC. The extracted
excitation function shows a maximum cross-section of ~ 82 mb at about 24 MeV. According to the yield
calculations based on these results, the available cumulative no-carrier-added
186Re
(rhenium) yield is
7.76 MBq/Ah (0.21 mCi/Ah) over the energy region 27.3→13.4 MeV. The cross sections are shown in
Figure 1 and the corresponding thick-target yields in Figure 2, where they are compared with the values from the
relevant (p,n) and (d,2n) reactions.
References
1.
2.
F Tárkányi, A Hermanne, S Takács, F Ditrói, F Kovalev and A V Ignatyuk, Nucl. Instrum. and Meth. B 264
(2007) 389, and references therein.
F Szelecsényi, G F Steyn, Z Kovács, K Aardaneh, C Vermeulen, and T N van der Walt, Proc. 8th Int.
Conference on Methods and Applications of Radioanalytical Chemistry (April 2009), in press.
68
120
This work measured
This work eye guide
100
192
Cross-section (mb)
Os(p,3n)
186
Re
80
60
40
20
0
0
10
20
30
40
50
60
70
Proton energy (MeV)
Figure 1: Cross sections of the 186Os(p,3n)186Re nuclear reaction.
18
186W(p,n)186Re
16
186W(d,2n)186Re
Yield (MBq/Ah)
14
192Os(p,3n)186Re this work
12
10
8
6
4
2
0
0
5
10
15
20
25
Bombarding energy
Figure 2: Integral thick-target yields of the 186W(p,n)186Re, 186W(d,2n)186Re and 192Os(p, 3n)
nuclear reactions.
69
30
2.2.3 Synthesis of no-carrier-added (n.c.a.) [123I]mIBG
D D Rossouw1 and L Macheli1,2
1
of Chemistry, National University of Lesotho, Maseru, Lesotho
2 Department
The diagnostic and therapeutic applications of radioiodinated meta-iodobenzylguanidine (mIBG) in oncology and
cardiology are well documented [1,2]. Currently, isotopic exchange is the radioiodination method of choice,
rendering a product with a relatively low specific activity. During the past 10-15 years the synthesis and
applications of high specific activity no-carrier-added (n.c.a.) [*I]mIBG have also been reported [3-6].
N.c.a. [*I]mIBG might have certain clinical advantages over its carrier-added (c.a.) analogue such as higher
myocardial uptake [5]. The nuclear medicine community could benefit from the availability of n.c.a. [*I]mIBG, as
its limited availability might be the reason for the lack of progress in larger scale clinical research efforts. This
prompted us to investigate the radiosynthesis of this product, selecting the most recently described method found
in the literature.
Firstly, a suitable labelling precursor was successfully synthesized by following a literature method [7]. The
amino groups in the benzylguanidine molecule were firstly protected with a suitable protecting group in order to
enhance its solubility in non-aqueous solvents. This was followed by the introduction of a trialkyltin group at the
position of labelling. The radiolabelling was carried out by means of radioiodine-for-tin substitution. The whole
radiosynthesis procedure involved a radioiodination followed by a de-protection step. The former was carried out
in an acidic medium in the presence of an oxidizing agent, N-chlorosuccinimide (NCS), which converted the
radioiodide (123I) to radioiodine. The latter step was carried out in the presence of trifluoroacetic acid at 110°C to
remove the protecting group. The progress of both steps was followed by means of radio-High Performance
Liquid Chromatography (HPLC). A solid phase extraction technique was developed to purify reaction mixtures
and to isolate the pure labelled product. This was done by loading the neutralized reaction mixture onto a
cartridge containing the solid phase support and washing out all polar components of the reaction mixture with
water. The radiolabelled product was then eluted with a 0,1% phosphoric acid / ethanol mixture.
Labelling conditions obtained from literature [7] were optimized at low and high activity levels with regards to the
precursor and NCS contents. The radiochemical yields were initially assessed by means of analytical HPLC and
later also by determining Solid phase extraction isolated yields. The data in Table 1 show that low and
inconsistent HPLC radiochemical yields were obtained using 50-100 g of precursor together with 100-300 g of
NCS. Increasing the NCS content to 2000 g, while maintaining the same levels of precursor, resulted in higher
but still somewhat inconsistent yields. Increasing the precursor content to 200 g resulted in consistently high
HPLC yields at radioactivity levels up to nearly 3300 MBq. In order to incorporate higher amounts of activity into
reaction mixtures, a double scale up was required. Under this condition the radiochemical yield was similar to
that of a normal scale reaction (Table 1, last entry). The HPLC yields were also backed up by good and
consistent isolated yields. The lower isolated yields can be ascribed to activity losses during the purification step
as well as a general over-estimation of HPLC yields.
70
Mass precursor
Mass NCS
Starting
radioactivity
(MBq)
HPLC
radiochemical
yielda
(%)
Isolated
radiochemical
yieldb
(%)
(g)
(g)
50
100
50
100
200
400
100
300
2000
2000
2000
4000
37-140
37-180
115-130
484-2170
1900-3280
5340
39 ± 4 (n=2)
50 ± 28 (n=3)
87 ± 18 (n=5)
74 ± 23 (n=4)
98 ± 1.4 (n=4)
99 (n=1)
Not determined
Not determined
Not determined
Not determined
85 ± 2.2 (n=4)
86 (n=1)
a Assessed
by means of analytical HPLC
Isolated yield of n.c.a. [123I]mIBG after de-protection and solid phase extraction purification, expressed as a
percentage of the starting activity (decay-corrected).
b
Table 1: Distribution coefficients of elements on AG MP-50 in varying HF concentrations
Solid phase extraction isolated [123I]mIBG can easily be converted into a radiopharmaceutical by adding
phosphate buffer to adjust the pH and saline solution to lower the ethanol content. The radiochemical purity of
the product was in excess of 95% and the estimated specific activity was about 1 TBq mol-1. This is more than
3000 times higher than the specific activity of the carrier-added product. These results suggest that the described
procedure is feasible at activity levels up to at least 5000 MBq, yielding a good quality product.
References:
1.
2.
3.
4.
5.
6.
7.
W H Beierwaltes, Med. Ped. Oncol. 15 (1987)163.
A J McEwan, P Wyeth and D Ackery, Appl. Radiat. Isot. 37 (1986) 765.
G Vaidyanathan and M R Zalutsky, Appl. Radiat. Isot. 44 (1993) 621.
G Vaidyanathan and M R Zalutsky, Nucl. Med. Biol. 22 (1995) 61.
M Knickmeier, P Matheja, T Wichter, K P Schäfers, P Kies, G Breithardt, O Schober and M Schäfers, Eur.
J. Nucl. Med. 27 (2000) 302.
S Samnick, J B Bader, M Müller, C Chapot, S Richter, A Schaefer, B Sax and C M Kirsch, Nucl. Med.
Commun. 20 (1999) 537.
G Vaidyanathan, D J Affleck, K L Alston and M R Zalutsky, J Label. Comp. Radiopharm. 50 (2007) 177.
71
2.2.4 Investigation into various aspects of the labelling of a peptide with 68Ga
D D Rossouw1 and T Mochochoko1,2
1
of Chemistry, National University of Lesotho, Maseru, Lesotho
2 Department
In a continuation of the peptide radiochemical labelling evaluation studies, using iThemba LABS‟ newly developed
68Ge/68Ga
generator described in the 2007/2008 annual report, further work was conducted in which other
labelling parameters were investigated.
The elution of the tin dioxide based iThemba LABS generator has to be carried out with 0.6 M HCl instead of the
0.1 M HCl used for other commercial generators, due to the nature of the tin dioxide matrix. This necessitated
changes in the peptide labelling recipe. A recipe developed by a visiting Dutch scientist in 2008 was used and
proved to be efficient. In short, an amount of approximately 2 g modified peptide is mixed with a small amount
of 2.5 M sodium acetate solution, followed by addition of a certain volume of the 68Ga eluate. The volume ratio of
sodium acetate to eluate should be a constant value in order to ensure that the pH of the mixture remains in the
range of 3.5 - 4.0 for optimum complexation of the 68Ga by the modified peptide [1]. The concentration of
modified peptide in the reaction mixture is 0.018 g/l. The mixture is heated at 90°C for 5 minutes and the
labelling efficiency determined by means of radio-HPLC.
Volume 2.5M sodium
Volume 68Ga eluate
acetate solution
Concentration of
Labelling efficiency
peptide in reaction
mixture
(l)
(l)
(g/ l)
(%)
50
138
0.01
96.4 ± 0.9 (n=7)
76
208
0.007
96.5 ± 1.1 (n=8)
100
276
0.005
81.7 ± 12.8 (n=13)
200
552
0.003
44.7 ± 20.8 (n=4)
The main aim of this study was to determine to what extent the reaction can be scaled up without having to
increase the peptide content. This was done in order to save on the fairly expensive modified peptide, as well as
to increase the specific activity of the labelled product. A proportional increase of sodium acetate and eluate
volumes was done, while maintaining the peptide content at a 2 g level. This resulted in increases in the
radioactivity content of reaction mixtures. HPLC analysis results in Table 1 show that labelling efficiencies in
excess of 95% are consistently possible at a peptide concentration up to 0.007 g/l. This represents a
2.6 times scale up from the standard recipe, without having to increase the peptide content.
72
At lower
concentrations the labelling efficiencies starts dropping and become fairly inconsistent. Under these conditions
the peptide content should be increased.
Another area under investigation was the concentration of
68Ga
eluates on ion exchange resins and the
subsequent labelling of the peptide, using the concentrated eluates. Such a procedure would remove any
unwanted metallic impurities as well as any breakthrough 68Ge parent isotope that might be present. Both anion
and cation exchange resins were used, using known methodologies [1,2]. While the concentration on both types
of resin was successful, inexplicably poor labelling efficiency results were obtained using the concentrated 68Ga.
This will be further investigated.
References:
1.
2.
G J Meyer, H Mäcke, J Schuhmacher, W H Knapp and M Hofmann, Eur. J. Nucl. Med. Mol. Imaging 31
(2004) 1097.
K P Zhernosekov, D V Filosofov, R P Baum, P Aschoff, H Bihl, A A Razbash, M Jahn, M Jennewein and
F Rösch, J. Nucl. Med. 48 (2007) 1741.
2.2.5 Radiosynthesis of various radioiodinated pyrimidine nucleoside derivatives and
determining their uptakes into cells
D D Rossouw1 and L Taleli2
1iThemba
Laboratory for Accelerator Based Sciences, PO Box 722, Somerset West, 7129, South Africa
Faculty of Applied Sciences, Cape Peninsula University of Technology, PO Box 1906, Bellville, 7535, South
Africa
2
The use of halogenated pyrimidine nucleosides for studying the metabolic pathways of pyrimidine nucleoside
incorporation into DNA and for measuring cell proliferation dates back more than 30 years [1]. Studies have
demonstrated a substantial incorporation of radiolabelled 5-iodo-2‟-deoxyuridine (IUdR) into the DNA of tumours
and proliferating tissues [1]. Auger electron emitters (e.g. 123I, 125I) have been proposed as attractive alternatives
to energetic -emitters (e.g.
131I)
for use in cancer therapy. IUdR is a thymidine (TdR) analogue in which the
5-methyl group of TdR is replaced by iodine. It has been found that radiopharmaceuticals such as *IUdR,
labelled with
123I
or
125I,
are highly radiotoxic to mammalian cells and exceedingly efficacious in the therapy of
small animal malignancies when these radionuclides decay in proximity to nuclear DNA [2]. The short half-life of
IUdR in vivo, its rapid dehalogenation in the liver, and its cellular uptake only in the S phase of the cell cycle are
limiting factors in the use of this compound. Obtaining high uptake of IUdR by tumour cells and high tumour-tonontumour ratios after intravenous administration remains a challenge [2]. The classical labelling method is the
introduction of the radioiodine in the 5-position of the uracil ring. The size of the iodine atom is comparable to that
of the methyl group in TdR, therefore IUdR behaves remarkably like TdR [3]. Recently the syntheses of some
fluorinated N-3(substituted) analogues of thymidine have also been reported [4]. Although these compounds
were specifically designed for 18F labelling, the chemistry also allows for the synthesis of similar radioiodinelabelled analogues. The only difference is that the iodine atom would be situated in a more stabilized position,
e.g. an iodovinyl group. To the best of our knowledge, there is no documented information on the cell uptakes of
73
radioiodinated N-3(substituted) analogues of thymidine. The objective of this study was therefore to synthesize
radiolabelled N-(3-iodoprop-2-en-1-yl)-thymidine (both cis-and trans-isomers) and to determine and compare their
cell uptakes with that of the conventionally radiolabelled IUdR.
O
O
H3C
I
HO
O
OH
IUdR
N
I
N
NH
O
HO
O
N
O
OH
N-(3-iodoprop-2-en-1-yl)-thymidine
A tetrahydropyranyl (THP)-protected labelling precursor, N-(3-tributyltin-prop-2-en-1-yl)-3‟,5‟-THP-thymidine
(trans-isomer) was successfully synthesized. The THP groups had been introduced to protect the hydroxyl
groups in the sugar moiety during the chemical modification of the thymidine molecule. Radiolabelling was
carried out by means of electrophilic iododestannylation. This was followed by removal of the THP groups under
acidic conditions. All the reactions were monitored by means of radio-HPLC. The identity of the radiolabelled
product was confirmed by comparison of its HPLC retention time with that of its authentic non-radioactive
analogue. The latter compound‟s chemical structure and its correct trans configuration were confirmed by
nuclear magnetic resonance spectroscopy and mass spectrometry. Attempts will also be made to synthesize the
cis-isomer. The cell uptake studies will be carried out in the near future.
References:
1.
2.
3.
4.
J G Tjuvajev, H A Macapinlac, F Daghighian, A M Scott, J Z Ginos, R D Finn, P Kothari, R Desai, J Zhang,
B Beattie, M Graham, S M Larson and R Blasberg, J. Nucl. Med. 35 (1994) 1407.
E S Semnani, K Wang, S J Adelstein and A I Kassis, J. Nucl. Med. 46 (2005) 800.
C F Foulon, Y Z Zhang, S J Adelstein and A I Kassis, Appl. Radiat. Isot. 46 (1995) 1039.
M M Alauddin, P Ghosh and J G Gelovani, J Label. Comp. Radiopharm. 49 (2006) 1079.
74
2.2.6 A more effective way of separating 52Fe from its Ni target material
N P van der Meulen1, A K Pakati1, T N van der Walt2, G F Steyn1, C Naidoo1
iThemba LABS, PO Box 722, Somerset West 7129, South Africa
Africa
1
2
52Fe
(t1/2 = 8.27 h) is a useful radionuclide for studying the biochemistry of iron-based compounds with potential
applications in nuclear medicine [1]. It is also used as the parent material in 52Fe/52Mn generators such that the
short-lived 52Mn (t1/2 = 21.1 min) can be obtained [2, 3]. Both 52Fe and
52mMn
decay characteristics make them useful for quantitative PET studies [4].
52Fe
are positron-emitters and their
has also been proven useful in
determining increased cerebral uptake in Wilson‟s Disease [5], as well as in increasing radiation dose to marrowbased diseases before bone marrow transplantation [6].
The proton bombardment of a Ni target using medium energy protons, as well as a radionuclide separation
method for this production, has been reported previously [7]. While the separation is effective, it is very timeconsuming and an alternative method was sought to improve working conditions.
The Ni target was placed in a 64 to 43 MeV production energy window, with a production rate of 25.8 MBq/Ah.
The target consisted of 7.8 g Ni powder, compacted and annealed a number of times to produce a final thickness
of about 3 mm and a diameter of 20 mm. The bombarded target was dissolved in 3.5 M HNO 3, after which the
solution was evaporated to insipient dryness and picked up in 8.0 M HCl. The solution was pumped through a
5 ml column containing Amberchrom CG161m adsorption resin, where the 52Fe was retained. Any impurities
were removed from the resin column by passing more 8.0 M HCl through it. The 52Fe was eluted from the resin
using 0.1 M HCl. The final product proved to be chemically and radionuclidically pure. This method proved to be
very effective, as a greater yield can be obtained by eliminating unnecessary time constraints.
References
1.
2.
3.
4.
5.
6.
7.
W H Knospe, G V S Rayudu, M Cardello, A M Friedman, E W Fordham, Cancer 37 (1976) 1432.
T H Ku, P Richards, L G Strang Jr, T Prach, Radiology 132 (1979) 475.
R M Lambrecht, Radiochim. Acta 34 (1983) 9.
M Lubberink, V Tolmachev, S Beshara, H Lundqvist, Appl. Radiat. Isot. 51 (1999) 707.
M Bruehlmeier, K L Leenders, P Vontobel, C Calonder, A Antonini, A Weindl, J. Nucl. Med. 41 (2000) 781.
C Jacquy, A Ferrant, N Leners, M Cogneau, F Jamar, J L Michaux, Bone Marrow Transplantation 19
(1997) 191.
P Smith-Jones, R Schwarzbach, R Weinreich, Radiochim. Acta 50 (1990) 33.
75
2.2.7 Method Development for the separation of 22Na from Mg target material
N P van der Meulen1, T N van der Walt2
iThemba LABS, Radionuclide Production, PO Box 722, Somerset West, 7129, South Africa
Africa.
1
2
22Na
(t1/2 = 2.60 years) is a sought-after commodity in the form of positron sources, where iThemba LABS is
currently the sole manufacturer. It is used for energy and efficiency calibrations of -spectrometers, tracer studies
in agriculture and biology [1, 2] and in nuclear medicine [3].
A number of methods have been reported in the literature with regard to the separation of sodium from
magnesium [1, 2, 4, 5] and a modified method of [1] was put into production at iThemba LABS in the mid-1990‟s
[6].
This method has a number of drawbacks, making the production excruciatingly sensitive. The 8 g Mg target is
rinsed with 0.5 M HCl, before being transferred to a reaction vessel where it is dissolved in 3.5 M citric acid at
55ºC. This process takes 12 hours. It is important to control the temperature of the dissolution step carefully, as
insoluble magnesium citrate precipitate is formed at temperatures above 60ºC making it almost impossible to
dissolve and proceed with the production method.
The solution is then cooled with the addition of one litre of ice cold 1.0 M TEA – 80% methanol, before the
resultant solution is loaded on to a 10 ml column containing AG MP-50 macroporous cation exchange resin. The
remaining Mg on the column is then eluted with 0.2 M citric acid – 0.6 M TEA – 80% methanol, before the column
is rinsed with 0.1 M EDTA – 0.6 M TEA. Remaining traces of TEA and EDTA is removed from the column by
passing water through it, and the column is then converted to the ammonium form using 1.0 M NH4OH – 80%
methanol. Any remaining traces of NH4OH and methanol is removed by passing water through the resin column,
before the 22Na final product is eluted from the column using 1.0 M (NH4)2CO3. The eluate is passed through a
10 ml column containing Chelex 100 resin (to finally remove remaining contaminants) before being evaporated to
dryness.
The time taken to perform the above-mentioned production procedure from dissolution to elution takes 24 hours,
after which a further 28 hours is needed for the evaporation stage. While the time taken to perform the
evaporation can be overcome with the construction of a larger evaporator unit, the production method had to be
addressed.
The 8 g Mg target was transferred to a reaction vessel and concentrated Suprapur HCl added to it drop-wise to
regulate the reaction rate. Once the target material had dissolved, the resultant solution was evaporated to
dryness, before picking up the residue in water and combining it with 1.4 l of 0.1 M EDTA – 0.6 M TEA. The
resultant solution is loaded on to a column containing 10 ml AG MP-50 cation exchange resin and the column
rinsed with water, NH4OH – methanol, and water, as described above. The 22Na is eluted as before. 95% of the
22Na
is eluted, with a radiochemically pure product being obtained. As purification of solvents is required as part
76
of the preparation for the production (to remove any non-radioactive Na), the revised method is seen as a
considerable improvement and will be put into use for production in due course.
References
1.
2.
3.
4.
5.
6.
R J N Brits, F von S Toerien, Appl. Radiat. Isot. 39 (1988) 1045.
H Ravn, W H Schulte, C Rolfs, F B Waanders, R W Kavanagh, Nucl. Instr. Meth. Phys. Res. B 58 (1991)
174.
T Smith, C J Edmonds, Nucl. Med. Comm. 8 (1987) 655.
J W Irvine Jr, E T Clarke, J. Chem. Phys 10 (1948) 686.
B Z Iofa, M S A Dzhigirkhanov, A G Maklachkov, V P Ovcharenko, Yu G Sevat‟yanov, A I Silant‟ev, Sov.
Radiochem. 29 (1988) 655.
T N van der Walt, F J Haasbroek, In: Synthesis and Applications of Isotopically Labelled Compounds, Ed.
J Allen (1994). John Wiley & Sons Ltd, 211.
2.2.8 The separation of 88Y from its Nb capsule target material
N P van der Meulen1, C M Perrang1, M R van Heerden1
1
iThemba LABS, PO Box 722, Somerset West, 7129, South Africa
88Y
(T1/2 = 106.6 d) can be effectively produced by means of a cyclotron. Its mode of decay is predominantly by
means of electron capture and the decay emissions include the strong -rays of 898.0 keV (93,7%) and
1836.1 keV (99,2%), respectively [1].
88Y
can be produced with protons via the reaction 88Sr(p,n)88Y and a production method had recently been
conceived using SrCl2 target material [2]. However it can also be obtained as a product from 88Zr/88Y generators
that can be produced by separating 88Zr from bombarded niobium capsules [3, 4]. This method was thought to be
cumbersome, and a more user-friendly method needed to be devised.
88Y
is used as small point sources in the calibration of instruments, as well as in the determination of mixtures
containing Sr radionuclides [5], the accurate determination of yttrium in superconductive oxide ceramics [6], and
as a substitute for
90Y
(a β-emitter radionuclide used for therapy) to quantify the biodistribution of
Y-pharmaceuticals in animals [7]. It is used effectively as tracer for the chemical yield determination of 90Y [8].
Distribution coefficients (Kd) were obtained for Y, Zr and Nb on AG MP-50 and AG 50W-X4 cation exchange
resins in various concentrations of HF (see Table 1).
Kd values of AG MP-50 in HF media
HF concentration
0.1 M
0.2 M
0.5 M
1.0 M
2.0 M
Y(III)
>104
>104
>104
>104
>104
Zr(IV)
6.4
<1
<1
<1
<1
Nb(V)
<1
<1
<1
<1
<1
77
Based on the results obtained above, the bombarded Nb capsule was dissolved in 2.0 M HF (containing a few
drops of HNO3 to speed up the dissolution process) and the resultant solution passed through a 10 ml column
containing AG MP-50 macroporous cation exchange resin, retaining the 88Y. The column was rinsed with 2.0 M
HF to remove any 88Zr and Nb contaminants, before the 88Y final product was eluted with 7.0 M HCl and
evaporated to dryness. The product, a 100% yield which is radiochemically pure, was picked up in 0.1 M HCl.
This method is useful for production purposes as it does not require extra beam time to produce. It merely
requires the processing of bombarded Nb target capsules from other productions.
References
1.
2.
3.
4.
5.
6.
7.
8.
R B Firestone, L P Eckström, WWW Table of radioactive isotopes Version 2.1 (2004) URL:
<http://ie.lbl.gov/toi>.
N P van der Meulen, T N van der Walt, G F Steyn, F Szelecsényi, Z Kovács, C M Perrang,
H G Raubenheimer, Appl. Radiat. Isot. (2009) in press.
M Fassbender, F M Nortier, D R Phillips, V T Hamilton, R C Heaton, D J Jamriska, J J Kitten, L R Pitt,
L L Salazar, F O Valdez, E J Peterson, Radiochim. Acta 92 (2004) 237.
M Fassbender, D J Jamriska, V T Hamilton, F M Nortier, D R Phillips, J. Radioanal. Nucl. Chem. 263
(2005) 497.
M A Lone, W J Edwards, R Collins, Nucl. Instr. Meth. Phys. Res. A332 (1993) 232.
K Shikano, M Katoh, T Shigematsu, H Yonezawa, J. Radioanal. Nuclear Chem. 119 (1987) 433.
G L Griffiths, S V Govindan, R M Sharkey, D R Fischer, D M Goldenberg, J. Nucl. Med. 44 (1993) 77.
A Arzumanov, A Batischev, N Berdinova, A Borissenko, G Chumikov, S Lukashenko, S Lysukhin,
Yu Popov, G Sychikov, In: Cyclotrons and Their Applications, Sixteenth International Conference, East
Lansing, Michigan, Ed. F. Marti (2001) 34.
78
2.2.9 Preparation and characterisation of iThemba LABS 68Ge/68Ga generator
C Naidoo1, D M Prince1, C Davids1, R de Wee1, G Sedres1, E Hlatshwayo1 and D D T Rossouw1
1iThemba
LABS, PO Box 722, Somerset West, 7129, South Africa
Since the 1970's, several 68Ge/68Ga generator systems have been developed in an attempt to provide a reliable
source of the positron-emitter 68Ga (half-life 68 min) that can readily be converted into radiopharmaceuticals for
use in Positron Emission Tomography (PET) studies. However, it is only recently that
68Ga
has seen a
renaissance. Firstly, PET has developed from a research tool to a routine clinical application over the last
decade. Secondly, 68Ge/68Ga generators with suitable properties for labelling in a clinical environment have
become available. Thirdly, small peptides showing suitable pharmacokinetic properties and which can be
labelled with 68Ga at high specific activity have also become available. iThemba LABS has launched a 68Ge/68Ga
generator which complies with current Good Manufacturing Practice (cGMP).
The preparation and
characterisation of this generator, together with the radiolabelling efficiency of a DOTATOC
[1,4,7,10-tetraazacyclodecane-N,N/,N//,N///-tetraacetic acid –
DPhe
1-Tyr3-octreotide]
peptide with
68Ga,
was
determined.
A 30 mCi (1110 MBq) 68Ge/68Ga generator was prepared by loading the parent 68Ge (half-life 271 days) onto a
modified tin dioxide column [1]. The generator was eluted daily with 5 ml suprapur 0.6 M HCl and the following
parameters were determined: a) 68Ga elution profiles, b) 68Ge breakthrough levels, c) metal contaminants (Ga,
Ge, Al, Cu, Ti, Sn, Fe and Zn), d) pH and e) sterility. The 68Ga was quantified using a Capintec Ionisation
Chamber and the 68Ge breakthrough was determined 24 h post elution using the standard calibrated HPGe
detector coupled to a multi-channel analyser. The eluate was analysed using a Jobin-Yvon Ultima Inductively
Coupled Plasma Spectrometer (ICP) to determine the metal contaminants. DOTATOC was labelled with 68Ga
according to the Breeman, et al. method [2].
The 68Ga efficiency profile is illustrated in Figure 1 and 68Ge breakthrough in Figure 2. The 68Ge/68Ga generator
showed reliable stability, while the metal contaminants, pH and sterility were all within the desired specifications.
The labelling efficiency of DOTATOC with 68Ga was consistently more than 95%.
130.00
120.00
68
Ga Efficiency (%)
110.00
100.00
90.00
80.00
70.00
60.00
50.00
0
10
20
30
40
Time (days)
Figure 1: 68Ga efficiency
79
50
60
70
80
0.001
0.0009
68
Ge Breakthrough (%)
0.0008
0.0007
0.0006
0.0005
0.0004
0.0003
0.0002
0.0001
0
1
5
11
15
20
27
33
35
40
46
50
54
57
71
Time (days)
Figure 2: 68Ge breakthrough
References
1.
2.
K Aardaneh and T N van der Walt, Ga2O for target, solvent extraction for radiochemical separation and
SnO2 for the preparation of a 68Ge/68Ga generator, J. Radioanal. Nucl. Chem. 268 (2006) 25-32.
W A P Breeman, M de Jong, E de Blois, B F Bernard, M Konijnenberg and E P Krenning, Radiolabelling
DOTA-peptides with 68Ga, Eur. J. Nucl. Med. Mol. Imaging 32 (2005) 478-485.
80
Physics Group
2.3 Physics Group
2.3.1 Candidate chiral bands in 198Tl
E A Lawrie1, P A Vymers1,2, Ch Vieu3, J J Lawrie1, C Schück3, R A Bark1, R Lindsay2, G K Mabala1,4, S M
Maliage1,2, P L Masiteng1,2, S M Mullins1, S H T Murray1, I Ragnarsson5, T M Ramashidzha1,2, J F SharpeySchafer1,2 and O Shirinda1,2
1iThemba
LABS, P O Box 722, Somerset West 7129, South Africa
of the Western Cape, Private Bag X17, Bellville 7525, South Africa
3Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, CNRS – IN2P3, F-91405 Orsay, France
4Department of Physics, University of Cape Town, Rondebosch 7700, South Africa
5Division of Mathematical Physics, LHT, Lund University, SE-221 00 Lund, Sweden
2University
Excited states in
198Tl
were populated in the
197Au(,3n)
reaction at a beam energy of 40 MeV.
Two
complementary experiments were performed. The first one was carried out at Orsay, France and was dedicated
to electron-gamma spectroscopy. The Orsay electron spectrometer comprises two Kleinheinz magnetic lenses
positioned at 90 and 180 with respect to the beam direction, which direct the internal conversion electrons
towards two segmented Si(Li) detectors. Eight large Ge detectors were positioned in the hemisphere opposite to
the 90 magnetic lens and used to detect the emitted -rays. The data were used to search for low energy
transitions and also to assign multipolarity to the transitions by measuring their internal conversion coefficients.
The second experiment was performed at iThemba LABS. It was dedicated to -ray spectroscopy and employed
the AFRODITE -ray array, consisting of eight clover and six LEPS detectors. The data analysis comprised:
(i) - coincidence analysis, (ii) directional correlation from oriented states ratios and linear polarization
measurements and (iii) -ray intensity measurements.
The previously known level scheme of 198Tl [1] was considerably extended by adding new transitions above the
15- level of the previously known Band 1, by discovering two new bands and several other new transitions. The
extended level scheme of
198Tl
is shown in Figures 1 and 2. The analysis of our two data sets resulted in
unambiguous spin and parity assignment to most of the new levels.
Figure 1: Part 1 of the level scheme of 198Tl. The widths of the arrows represent the transition intensities. Tentative transitions are
shown in brackets. The excitation energy is given with respect to the 7+ level.
81
Physics Group
Figure 2: Part 2 of the level scheme of 198Tl. Notation as in Figure 1.
The low-spin structures in
198Tl
have been assigned two-quasiparticle configurations [1]. The 7+ state was
associated with a s1/2  i13/2 configuration coupled to a weakly deformed oblate core with  = -0.08. The
positive parity states situated above the isomeric state at excitation energy of 143 keV (with a lifetime of 150 ns)
were assigned a h9/2  j (where j stands for orbitals from the p3/2, f5/2, and p1/2 shells) and associated with
moderately deformed shape with  = -0.14.
Band 1 develops above the 8- isomeric level (lifetime of 12.3 ns) and has been previously assigned a h9/2 
i13/2 configuration coupled to a deformed core with  = -0.15. The new Band 2 is associated with a h9/2  i13/22
j configuration. No configuration other than a h9/2  i13/2 can match the spin and parity of Band 3. This band
does not seem likely to be resulting from a coupling with -vibrations of the core, because no low-energy
-vibrational states have been found in the
198Hg
core, or in the odd-mass neighbours. Our calculations using
two-quasiparticle-plus-triaxial-rotor model suggested that Bands 1 and 3 could be chiral partner bands. A
summary of these results was published in Ref. [2], while a paper reporting the full details of this study was
submitted for publication [3].
References
1. A J Kreiner et al., Nucl. Phys. A 282 (1977) 243.
2. E A Lawrie, P A Vymers, Ch Vieu, J J Lawrie, R A Bark, R Lindsay, G K Mabala, S M Maliage, P L Masiteng,
S M Mullins, S H T Murray, I Ragnarsson, T M Ramashidhza, C Schück, J F Sharpey-Schafer and O Shirinda,
Phys. Rev. C 78 (2008) 021305(R).
3. E A Lawrie, P A Vymers, Ch Vieu, J J Lawrie, C Schück, R A Bark, R Lindsay, G K Mabala, S M Maliage,
P L Masiteng, S M Mullins, S H T Murray, I Ragnarsson, T M Ramashidhza, J F Sharpey-Schafer and
O Shirinda, Phys. Rev. C, submitted.
82
Physics Group
2.3.2 Possible Chiral Bands in the doubly-odd 194Tl nucleus
P L Masiteng1,2, E A Lawrie1, T M Ramashidzha1,2, J J Lawrie1, R A Bark1, J Kau1,3, F Komati1,3, S M Maliage1,
I Matamba4, S M Mullins1, S H T Murray1,5, K P Mutshena1,4, J F Sharpey-Schafer1, P Vymers1,2, Y Zhang1,5
1iThemba
of the Western Cape, Private Bag X17, Bellville 7535, South Africa
3University of North West, Private Bag X2046, Mmabatho 2735, South Africa
4University of Venda for Science and Technology, Thohoyandou, South Africa
5University of Cape Town, Private Bag, Rondebosch 7701, South Africa
2University
High-spin states of
194Tl
were studied using the AFRODITE array at iThemba LABS. The
evaporation reaction at 91 and 93 MeV was used to populate high-spin states in
194Tl.
181Ta (18O,5n)
fusion
The experiment was
performed for two weekends. The target consisted of stacks of three and two thin metallic tantalum foils with
thickness of 0.5 mg/cm2 each in the first and the second weekend respectively. The emitted –rays were detected
by the AFRODITE array [1], which consisted of eight clovers and six LEPS detectors. The analysis of the data
involved (i) a study of the -ray coincidence relationships, and (ii) directional correlation from oriented states and
linear polarization measurements to deduce the spin and parity of the levels.
The analysis of the coincidences for the 194Tl data set resulted in the extension of the previously known negative
parity band [2], here called Band 1. Four new bands were also observed. The spins and the parities were
assigned to the new levels with the help of the results of the directional correlation from oriented states ratio and
the linear polarization measurements. The yrast band has been assigned a h9/2  i13/2 configuration [2]. This
proton–particle neutron-hole configuration is suitable for a chiral system. Band 4 also has negative parity and
probably the same configuration as the yrast band. More detailed argument can be found in [3]. The excitation
energy and the staggering plots for these bands in 194Tl are shown in Figure 1.
Figure 1: Excitation energy (left panel) and staggering, S(I)=[E(I)−E(I−1)]/(2(I)) (right panel),
in the negative parity bands in 194Tl.
.
In the region of I = 18–20ħ Band 1 and Band 4 undergo band crossings, at about the same rotational frequency
of about 0.3 MeV. Band 3 crosses Band 1 at a rotational frequency of 0.275 MeV. Bands 1 and 4 have the same
alignments of about 18ħ above the band crossings, while the alignment of Band 3 is about 16ħ. Such large
alignments and moderate band crossing frequencies are consistent with excitation of two more i 13/2 neutrons. The
interesting question then will be whether some of these bands are chiral partners. In particular, Band 1 and
83
Physics Group
Band 4 may be good candidates for chiral bands. Band 4 has relative excitation energy of about 377 keV with
respect to the yrast band at I = 13ħ, which decreases at higher spins. Above the band crossing it is only 37 keV at
I = 21ħ.
The measured quasiparticle alignments, kinematic moments of inertia and the preliminary B(M1)/B(E2) reduced
transition probability ratios for the three negative parity bands are presented in Figure 2. Many of the properties of
Bands 1 and 4 agree with the fingerprints for chirality such as: (i) the small relative excitation energy of Band 4
with respect to Band 1. (ii) Similar alignments, in particular above the band crossing, (iii) similar moments of
inertia, in particular above the band crossings, (iv) similarity in the band crossing regions of both bands. Indeed
both bands undergo band crossings at about the same rotational frequency. Some of their properties, however,
disagree with the fingerprints for chirality such as: (i) Band 1 exhibits energy staggering with a large amplitude
while Band 4 shows no energy staggering. These patterns persist also after the band crossings. (ii) The
preliminary B(M1)/B(E2) ratios seem to differ.
Figure 2: Experimental quasiparticle alignments, and Rothians, (calculated with reference parameters
J0 = 8ħ2/MeV and J1 = 40ħ4/MeV), kinematic moment of inertia, and preliminary values for the
B(M1)/B(E2) ratios of the reduced transition probabilities, for the negative parity bands in 194Tl.
References
1. R T Newman et al., Balkan Phys. Lett. 182 (1991), special issue.
2. A J Kreiner et al., Phys. Rev. C 20 (1979) 2205.
3. P L Masiteng et al., Acta Physica Polonica B 40 (2009) 657.
84
Physics Group
2.3.3 Analyzing power and cross section distributions of the 12C(p, p)8Be cluster
knockout reaction at an incident energy of 100 MeV
J Mabiala1,2, A A Cowley1,2, S V Förtsch2, E Z Buthelezi2, R Neveling2, F D Smit2, G F Steyn2 and J J van Zyl2
1Department
2iThemba
of Physics, University of Stellenbosch, Private Bag X1, Matieland, South Africa
Quasifree alpha-cluster knockout reactions on light- and medium-mass nuclei have been investigated by several
authors over the past years. Since a free alpha particle is a particularly stable configuration, it is tempting to
predict the existence of alpha-clusters in nuclei. One might ask whether these clusters are real entities or simply a
way of carrying out calculations to describe observables appropriately for a many-body system.
The most direct experimental method of studying ground-state alpha-clustering in nuclei is by means of a
knockout reaction [1, 2, 3, 4, 5]. In such a reaction, the knocked out cluster is observed in coincidence with the
projectile. In fact, the existence of clusters of nucleons would clearly be supported if the momentum distribution of
the clusters deduced from the coincidence spectra of emitted particles is in agreement with the expected
“preformed” cluster bound in the target nucleus. Moreover, the absolute spectroscopic factors extracted from the
coincidence results should in principle be in agreement with theoretical expectation.
Previous studies for the alpha-cluster structure of the ground state wave function of light as well as of mediummass nuclei gave good shape agreement between distorted wave impulse approximation (DWIA) calculations
and experimental energy-sharing cross section data [2, 3, 4, 6, 7, 8]. In addition, agreement between extracted
spectroscopic factors and theoretical expectations was also observed.
However, with polarized proton beams, more detailed tests of the DWIA description of (p,p) reactions become
possible. For example, measurements of (p,p) analyzing powers can be compared to analyzing powers
measured in free p-4He elastic scattering and in this treatment, these two quantities should be identical [3].
Therefore the ability to reproduce experimental analyzing powers acts as a more rigorous test of the reaction
dynamics, which consequently influences conclusions drawn about the cluster structure of the studied nuclei
[8, 9].
In this work, the (p,p) quasifree cluster knockout reaction on 12C was investigated experimentally at iThemba
LABS using polarized incident protons of 100 MeV. Coincident cross section and analyzing power energy-sharing
distributions were obtained at ten quasifree angle pairs for proton angles ranging from 25° to 110°. The data
were interpreted in terms of a DWIA theory [10]. Since measurements of analyzing powers were made, spin-orbit
distortions were included in DWIA calculations and were found to have negligible effect, especially around the
quasifree peak where the alpha-cluster momentum is small. The factorization approximation, where the two-body
p- cross section enters as multiplicative factor in the three-body (p,p) cross section expression, is valid; this is
shown in Figure 1 (left panel). The angular distribution of the analyzing power at the quasifree peak follow the
trend of free p-4He elastic scattering data remarkably well and comparisons with DWIA predictions are also in
good agreement (Figure 1, right panel). The energy-sharing spectra show a prominent quasifree-knockout
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Physics Group
contribution, from which we obtain an alpha absolute spectroscopic factor of 0.73. This value is in excellent
agreement with previous experimental results and theoretical predictions.
Figure 1: Cross sections (left panel) and analyzing powers (right panel) for the quasifree peak (zero recoil momentum) as a function of
the two-body p- c.m. scattering angle. Extracted cross section data from 12C(p,p)8Be (left panel) have been corrected for variation
in distortions using DWIA calculations and normalized to free p+4He scattering. The curves in both panels represent DWIA
calculations.
In conclusion, these results imply the existence of preformed α-clusters in 12C, with a two-body interaction
response between the projectile and the -cluster that resembles the scattering of protons from a free α-particle
to a remarkable extent.
References
1. A Nadasen et al., Phys. Rev. C 23 (1981) 2353.
2. T A Carey, P G Roos, N S Chant, A Nadasen, and H L Chen, Phys. Rev. C29 (1984) 1273.
3. C W Wang et al., Phys. Rev. C 31 (1985) 1662.
4. P G Roos et al., Phys. Rev. C 15 (1977) 69.
5. C Samanta, N S Chant, P G Roos, A Nadasen, and A A Cowley, Phys. Rev. C 26 (1982) 1379.
8. T Yoshimura et al., Nucl. Phys. A 641 (1998) 3.
9. R Neveling et al., Phys. Rev. C 66 (2002) 034602.
10. N S Chant and P G Roos, Phys. Rev. C 15 (1977) 57.
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Physics Group
2.3.4 A Global Investigation of the Fine Structure of the Isoscalar Giant Quadrupole
Resonance: the low-mass region 12≤A≤40
I Usman1,2, J Carter1, R Neveling2, Z Buthelezi2, S V Förtsch2, H Fujita1, 2, Y Fujita3, F D Smit2, R W Fearick4, G R
J Cooper5, E Sideras-Haddad1, P von Neumann-Cosel6, A Richter6, A Shevchenko6 and J Wambach6
1School
of Physics, University of the Witwatersrand, Johannesburg 2050, South Africa
3Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan
5School of Geophysics, University of the Witwatersrand, Johannesburg 2050, South Africa
6Institut fϋr Kernphysik, TU Darmstadt, Darmstadt 64829, Germany
2iThemba
Giant resonances are elementary excitation modes of nuclei. Theoretically, the first microscopic basis for the
description of giant resonances is the Random Phase Approximation. In this approach giant resonances are
treated as a coherent superposition of 1p-1h excitations in closed-shell nuclei [1]. However, the fine structure of
giant resonances, which carries unique information on the underlying physical nature and the dominant decay
mechanisms of the resonances, is still an unexplored topic in light nuclei (A ≤ 40). In view of this state of affairs,
high energy-resolution inelastic proton scattering experiments were performed with the K600 Magnetic
Spectrometer to investigate the fine structure of the Isoscalar Giant Quadrupole Resonance of the light nuclei
12C, 28Si, 27Al
and 40Ca. The extraction of the characteristic energy scales was performed using a Lorentzian
mother wavelet [2]. In addition, the semblance and dot product analysis techniques [3] were applied in order to
show quantitatively how the observed scales are isolated. This approach uses information on the phase angles
of the wavelet coefficients found in both experimental and theoretical data, and thus determines their level of
correlation. The dot product provides a better peak-to-valley ratio compared to semblance analysis which
depends only on the phase angles of the data. The results of the application of both semblance and dot product
to experimental and theoretical data sets are presented in Figure 1 for the case of 28Si. The theoretical data ware
obtained within the Second-Random Phase Approximation [4].
Another important aspect of proton inelastic scattering data with high energy-resolution is the use of it as a direct
measurement of level densities even in the excitation energy region of giant resonances. Level densities are of
fundamental interest not only as a test for the understanding of nuclear dynamics, but it also serves as a key
ingredient of large reaction-network codes in modelling stellar energy production and nucleosynthesis. This is
essential for an application of the fluctuation analysis technique and has been applied to the 40Ca(p,p‟) data at the
maximum of the Isoscalar Giant Quadrupole Resonance in the excitation energy region of between 10 and
20 MeV. Figure 2 presents the extracted spin and parity-dependent level densities in 40Ca using the modelindependent method of discrete wavelet transforms and quasifree knockout background determinations along
with the model predictions. While the Hartree-Fock Bogoliubov model underestimates the observed level
densities by a factor of two, it reproduces their energy dependence, the Back-Shifted Fermi Gas parameterisation
curves are in accordance with the data. Results indicate that experimentally extracted level densities are in better
accord with the Back-Shifted Fermi Gas model, as expected.
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Physics Group
References
1. J Speth and J Wambach, Int. Review of Nuclear and Particle Physics, Vol. 7, World Scientific, Singapore
(1991).
2. A Shevchenko, J Carter, G R J Cooper, R W Fearick, Y Kalmykov, P von Neumann-Cosel, V Yu Ponomarev,
A Richter, I Usman and J Wambach, Phys. Rev. C 77 (2007) 024302.
3. G R J Cooper and D R Cowan, Computers and Geosciences 34 (2008) 95.
4. P Papakonstantinou and R Roth, IKP TU Darmstadt (2009) Private Communication.
Figure 1: Energy spectra of 28Si at 12º scattering angle (green line) and the theoretical predictions of Second-Random Phase
Approximation (blue line) showing the extracted energy scales by applying the Lorentzian mother wavelet. The bottom two figures
represent the semblance and dot product analysis for a quantitative correspondence between the experimental data and the
theoretical predictions. Here, a value of 1 on the semblance plot corresponds to a perfect correlation, -1 to anti-correlation and 0 to no
correlation. The dot product uses the values of the wavelet coefficients as well to determine significant regions of correlation with 1
denoting strong correlation and strength.
Figure 2: Extracted spin and parity dependent level densities (Jπ = 2+ ) on 40Ca at 11º scattering angle (solid line) in comparison with
the theoretical Hartree-Fock Bogoliubov (HFB) calculations (dotted line) and the Back-Shifted Fermi Gas (BSFG) parameterisation
(dashed line).
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Physics Group
2.3.5 A search for the 2+ excitation of the Hoyle State
H Fujita1,2, M Freer3, Z Buthelezi1, J Carter2, S V Förtsch1, R Neveling1, S M Perez1,4, F D Smit1, I Usman1,2
1iThemba
of Physics, University of the Witwatersrand, Johannesburg 2050, South Africa
3School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
4Physics Department, University of Cape Town, Rondebosch 7700, South Africa
2School
Great interest exists in the so called Hoyle state, the 0+ 7.654 MeV excited state in 12C, because virtually all
matter as heavy and heavier than 12C passed through this state in the course of its stellar production cycle[1]. In
explosive processes extremely high temperatures are reached and the states well above the alpha-decay
threshold become important. In the current NACRE database [2] a 2+ state is suggested close to 9.2 MeV and
this has a strong influence on reaction processes in such scenarios. However, no such state has ever been
experimentally observed.
Inelastic proton scattering data were taken at iThemba LABS on 12C at an incident energy of 66 MeV and angles
of 10, 16, and 28 degrees. At this energy good energy resolution can be achieved and the contribution to the
measured width of states from the resolution of the spectrometer could then be minimized. Efforts were
concentrated on the 7 to 11 MeV range where a possible weak peak was found.
Figure 1: a) 12C excitation energy spectrum measured at 28. Contaminants from 16O (O) and 13C (C) are indicated. The blue and red
lines correspond to line-shapes with and without the 2+ contribution included. b) The 16° (blue) and 28° (red) data compared with
three resonant line-shapes (folded with the experimental resolution) for widths of 34 (dot-dashed), 42 (solid) and 50 (dashed) keV. c)
16° data. The blue and red lines correspond to line-shapes with and without the 2+ contribution included. The shaded region
corresponds to the R-matrix generated 2+ line-shape. The data points with associated error bars correspond to the calculated excess
yield between 8.8 and 10.6 MeV from 16O contaminants in the target from measurements with carbon and mylar targets at 200 MeV.
.
The experimental excitation energy resolution was determined from a Gaussian fit to the 7.65 MeV peak and
found to be 23 keV (FWHM). A detailed analysis of the 3- state is shown in Figure 1, with 3 resonance lineshapes determined from an R-matrix calculation (34, 42 and 50 keV). These line-shapes have been convolved
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Physics Group
with the experimental resolution. Figure 1b shows that the 34 and 50 keV line-shapes are in clear disagreement
with the data and a width of 42(3) keV is found (significantly larger than the presently accepted value).
As can be seen from Figure 1c, the 9.641 MeV peak has a tail. A possible weak state at 9.6(1) MeV with a width
of 600(100) keV is revealed. This situation repeated itself at the other angles suggesting a possible 2+ character.
Cluster calculations predict a peak in the 9-10 MeV region, and thus the present observations would be in
agreement with such models. Further measurements are planned for later this year.
References
1. F Hoyle, The Astrophysical Journal, Supplement Series, 1 (1954) 12.
2. C Angulo et al., Nucl. Phys. A 656 (1999) 3.
2.3.6 A feasibility study into the investigation of the (3He,8He) reaction
J A Swartz 1,2, E Z Buthelezi2, S V Förtsch2, H Fujita 2,3, J Mira2, R Neveling2, P Papka1,2, F D Smit2, and I Usman3
1Department
of Physics, University of Stellenbosch, Stellenbosch 7600, South Africa
3School of Physics, University of the Witwatersrand, Johannesburg 2050, South Africa
2iThemba
Very exotic nuclei can be studied in rare reactions using stable beams, with macroscopic intensities, and thick
targets. Exotic nuclei are interesting for a number of different reasons, e.g. for testing nuclear models under
extreme conditions of high isospins. In the case of very neutron-deficient nuclei, two-proton decay is the subject
of many theoretical investigations involving cluster and shell models [1-4]. Also, the mass calculation of nuclei
with A>20 on the proton drip line relies on the determination of the Coulomb energy which differs from the mirror
pair. The (3He,8He) reaction was investigated using the K600 magnetic spectrometer positioned at an angle of
θlab = 8° with a 220 MeV beam of incident 3He particles and a 27Al target. This reaction can be used to populate
highly neutron deficient nuclei. Should the study of this reaction prove to be feasible, a number of nuclei on the
proton drip line or beyond could be investigated at iThemba LABS.
The new data acquisition system, with the VME electronics and MIDAS software [6], was used along with one
new drift chamber, which consists of both an X wire-plane and a U wire-plane. An 1/8'' scintillator together with a
1/4'' scintillator was used as trigger detectors, with an additional 1/2'' scintillator used to veto energetic particles
that pass through the first two scintillators. We experimented with different trigger configurations and with placing
Al absorbers between the paddles. The field-settings for the magnets were adjusted in order to look for different
H and He isotopes in the focal-plane. The particles H, 2H, 3H, 3He, and 4He have been identified as outgoing
particles from the collision of 3He with 27Al. Experimental results for low-lying states populated in the (3He, 4He)
reaction are shown in Figure 1.
A discrete spectrum for the (3He,6He) reaction could not be identified, possibly because the cross section is too
low at such a large angle (θlab = 8°) to allow the accumulation of enough statistics within the time allotted to the
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Physics Group
feasibility study. For the same reason no 8He particles were observed. Note that the placement of the K600 at
8° represented the minimum attainable angle of the spectrometer at the time of the measurement.
Valuable experience was gained during this experiment with the 3He beam and with the measurement and
identification of the particles of interest with the magnetic spectrometer. In the short term a similar experiment,
this time with a 4He beam, should be performed since it is expected that two-neutron and four-neutron pick-up
reactions will be easier to measure than three- and five-neutron pick-up reactions. In the long term this
experiment should be repeated using the 0° mode of the K600 spectrometer.
References
1.
2.
3.
4.
5.
6.
L V Grigorenko et al., Phys. Rev. C 64 (2001) 054002.
L V Grigorenko et al., Nucl. Phys. A 713 (2003) 372; Erratum Nucl. Phys. A 740 (2004) 401.
H T Fortune et al., Phys Rev. C 76 (2007) 014313.
I V Poplavsky, Bull. Rus. Acad. Sci. Phys. 64 (2000) 795.
H T Fortune et al., Phys. Rev. C 73 (2006) 064310 .
The Midas Data Acquisition System, https://midas.psi.ch/, Paul Scherrer Institute, Switzerland.
Figure 1: The (3He,4He) reaction: the theoretically predicted particle identification (PID) spectrum for scintillator 1 versus time-of-flight
is shown at the top, while the middle represents the experimentally measured PID spectrum. A one-to-one correlation can be drawn
between what is predicted for the four particles that are expected to have the highest cross-sections (p, d, t and ), and the four most
prominent loci that were measured. In the bottom the position spectrum is shown for the 4He gate in the PID spectrum.
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Physics Group
2.3.7 Binary cluster model interpretation of the K-bands of odd-even nuclei models of
heavy nuclei
B Buck1, A C Merchant1, and S M Perez2,3
1Theoretical
Physics, University of Oxford, Oxford OX1 3NP, U.K
2iThemba
The strong coupling adiabatic model of Bohr and Mottelson [1] provides the basis for the standard interpretation
of the K-bands observed in deformed odd-even nuclei. In this model the bands arise when an appropriately
chosen intrinsic state of the even-even core generates a core – valence nucleon interaction having axial and
reflectional symmetries about a body-fixed OZ‟ axis and OX‟Y‟ plane respectively.
In an alternative approach Brink et al. showed [2] that K-bands are also produced in a model in which the eveneven core is characterised by a degenerate set of Jπ=0+,2+,4+… states having a common intrinsic component,
with the core nucleons coupled to the valence nucleon via an arbitrary nucleon-nucleon interaction.
We have previously found [3] that K-bands also emerge in calculations of the structure of deformed odd-even
nuclei using a binary cluster model for the even-even core. An understanding of this result can be obtained by
using a simple model in which the two clusters forming the even-even core are in a harmonic oscillator state of
their relative motion. Large values of the oscillator strength and of the principal quantum number N are then
implied by the large clusters corresponding to a strongly deformed system. For an even value of N the result is a
degenerate band of core states with orbital angular momenta LP=0+,2+,4+… These are found to have very similar
radial wavefunctions in the surface region, resulting in a novel interpretation of a common intrinsic state for the
band. With all radial integrals set to the same constant value an analytical diagonalization of the core – valence
nucleon interaction is then found to give rise to the K-bands [4].
References
1.
2.
3.
4.
A Bohr and B R Mottelson, Nuclear Structure Vols. 1 and 2 (New York: Benjamin) (1969).
D M Brink, B Buck, R Huby, M A Nagarajan and N Rowley, J. Phys. G 13 (1987) 629.
B Buck, A C Merchant and S M Perez, Nucl. Phys. A 644 (1998) 306.
B Buck, A C Merchant and S M Perez, (in preparation).
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Physics Group
2.3.8 Report on the Physics Target Laboratory
N Y Kheswa1, P Papka1, R Neveling1, R T Newman1
1 iThemba
A variety of targets was produced for nuclear physics experiments employing vacuum deposition and rolling
procedures in the last financial year. Targets were produced from natural and isotopically enriched materials. In
addition to the existing target manufacturing equipment, the design of sputtering equipment needed for production
of for example tungsten is underway. Furthermore the upgrade of the glove box is still in progress in order to
achieve an inert atmosphere desired for the production of targets which oxidize easily. Notable achievements
were:

completion of a vacuum target storage system comprising ten storage boxes;

successful development of a method for preparation of a solid (frozen)
136Xe
target under high vacuum
(P = 5.10-5 mbar). The xenon gas was frozen onto a solid gold substrate and a gold-plated copper
substrate, respectively. The substrates, placed at a tip of a copper cold finger connected to a liquid
nitrogen dewar, were cooled down to T ~ 55 K. Such conditions allowed a Xe target to last for between
4 and 8 hours between regeneration;

a computer program was written to determine the target thickness from measurements using a
228Th
radioactive source (alpha emitter).
A list of targets produced in the period covered by this report is given below. Attempts were also made to make a
tungsten target and targets involving the reduction of rare earth metals.
Target
natZr
natTa
70Zn
96Zr
181Ta
Bi on Ta
120Sn
40Ca
232Th
Xe-natural
Thickness (mg.cm-2)
0.3
0.3
5.2
14.5, 1.74, 0.77
15, 0.5, 1
1.65, 1.75, 2.45,
3.2
1
0.1-0.2
1
Production method
Rolling
Rolling
Vacuum evaporation
Rolling
Rolling
Vacuum evaporation
Vacuum evaporation, rolling
Vacuum evaporation
Vacuum evaporation
Freezing
Table 1: List of targets prepared in the Physics Target Laboratory during 2008-2009.
.
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Radiation Biophysics Group
2.4 Radiation Biophysics Group
2.4.1 The radiosensitizing effect of Ku70 knockdown in MCF10A cells irradiated with
low-LET photons and high-LET radiotherapy neutrons
V Vandersickel1, M Mancini2, J P Slabbert3, E Marras2, G Perletti2 and A Vral1.
1Department
of Basic Medical Sciences, Ghent University, Belgium
of Insubria, Varese, Italy
3iThemba LABS, Somerset West, South Africa
2University
The collaborative project between iThemba LABS and the Universities of Ghent (Belgium) and Insubria (Italy),
allowed us to conduct experiments to investigate molecular mechanisms that can increase the radiosensitivity of
cancer cells. In this work cellular damage in breast cells is examined following irradiation with p(66)/Be neutrons.
This treatment modality is used routinely at iThemba LABS in the treatment of breast cancer [1].
High-Linear Energy Transfer (LET) radiation, such as radiotherapy neutrons, may have potential benefits for the
treatment of some cancers that are inherently resistant to conventional treatment modalities. Some investigations
however showed that cancer cell lines that are resistant to photons are also resistant to high-energy neutrons [2].
A better understanding of the underlying mechanisms of DNA repair after low- and high-LET irradiations is
needed to provide guidance for using neutrons more efficiently in clinical radiotherapy. We investigate the
radiosensitizing effect after modulating the DNA repair capacity in a human mammary epithelial cell line
(MCF10A). This is done using lentiviral-mediated RNA interference (RNAi). For this, MCF10A cells were
transduced with lentiviral particles harbouring DNA sequences encoded for short-hairpin RNA specific for Ku70
RNA interference – Ku70 cell line. Cells were simultaneously mock-infected and used as control cultures –
LVTHM cell line. RNAi of Ku70, resulted in the stable knockdown of Ku70 proteins (Figure 1 and 2). These
proteins form a highly stable protein complex, the Ku heterodimer and this heterodimer plays an important role in
the non-homologous end-joining pathway for double strand break repair.
Figure 1: Western blotting after lentiviral-mediated RNAi of Ku70 in MCF10A cells (Ku70i). LVTHM cells served as control
cell line for RNAi experiments (mock-infected MCF10A cells). Monoclonal antibodies are used to visualize each subunit
after separation on a 10% polyacrylamide gel. Actin is used as a protein loading control.
94
Figure 2: Immuno-fluorescence images after expression of silencing of Ku70 by lentiviral RNA interference. Lower panels
show staining of Ku70. Upper panels show the corresponding 4',6-diamidino-2-phenylindole (DAPI) staining (blue).
To investigate a differential involvement of Ku70 in the repair of DNA lesions induced by neutrons and X-rays,
duplicate MCF10A (Ku70i and LVTHM) cultures were irradiated with either 6 MV X-rays or p(66)/Be neutrons.
The radiosensitizing effect of the Ku70/80 knockdown was evaluated using a cell proliferation assay (Figure 3).
A decrease in cell survival is noted for the Ku70i cell line following irradiation with either conventional X-rays or
neutrons. In this first set of readings the dose modifying factor for RNAi appears to be approximately the same
for low and high-LET radiations. This is most significant considering the different levels of repairable damage that
is induced by neutrons compared to X-rays. These results have important implications for molecular mechanisms
that can be exploited to increase the radiosensitivity of cancer cells to neutron therapy. For this reason additional
experiments are being conducted to confirm these observations.
Figure 3: Cell survival for MCF10A cells following lentiviral-mediated RNA interference (RNAi). Dose modifying factors for 6 MV X-rays
and for p(66)/Be neutrons are approximately equal.
References
1.
2.
E M Murray, I D Werner, G Schmitt, C Stannard, A Gudgeon, J Wilson, S Fredericks, E McEvoy, E Nel,
A Hunter, J P Slabbert, G Langman, Strahlenther. Onkol. 181 (2005) 77.
J P Slabbert, T Theron, F Zölzer, C Streffer and L Böhm, Int. J. Radiat. Oncol. Biol. Phys. 47 (2000)
1059.
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2.4.2 Crypt Cell Survival Measurements made in vivo at the end of a Spread-OutBragg-Peak show an increase in RBE for a Clinical Proton Beam
J Gueulette1, J P Slabbert2, J Martinez1, B de Coster1, J Symons2, J Nieto-Camero2
1Molecular
2iThemba
Imaging and Experimental Radiotherapy, Catholic University of Louvain, Belgium
LABS, Somerset West, South Africa
Using a novel jig to irradiate murine jejunum, a substantial increase in the relative biological effectiveness (RBE)
could be detected in the distal part of a Spread Out Bragg Peak (SOBP) for a 200 MeV proton beam [1]. Studies
to quantify the RBE at different positions of a SOBP for the 200 MeV proton beam at iThemba LABS continue.
The principle reason for this is to quantify RBE readings that are of clinical relevance.
In this work jejunum sections were ex-vivo irradiated in the middle, the very end and at a position between the
middle and the end of a 3 cm SOBP. The 3 cm SOBP was chosen for this study as smaller SOBP‟s are more
often use in proton therapy. The Perspex jig allows the irradiation of intestine segments with a diameter of about
3 mm. Using standard histology and HE staining the regeneration of crypt stem cells could be measured over a
wide range of doses. All histological samples were coded following randomization of mice into the different arms
of the study and analyzed as such. Repeat histological sections at least 2 mm apart in the jejunum were used for
counting.
Dose-effect relationships for crypt regeneration 3.5 days after irradiation at different depths in the 3 cm SOBP are
shown in Figure 1. Clear differences are noted for proton irradiations in the middle of the SOBP, the end of the
SOBP and halfway between the middle and end of the SOBP. Each data point is the average of the crypt counts
per circumference for 3 - 4 mice. The parallel exponential regression curves were fitted through the points by a
Figure 1: Dose-effect relationships for crypt regeneration in mouse jejunum after irradiations in the middle, the very end and a
position between the middle and end of 3 cm proton SOBP. The closed circles, closed triangles and closed squares correspond to
proton irradiations in the middle, halfway between the middle and the end, and at the end of the SOBP, respectively.
96
weighted least squares method. The error bars in Figure 1 correspond to the 95% confidence intervals.
Proton doses corresponding to an iso-effect of 20 regenerated crypts are 12.4 Gy, 11.8 Gy and 11.5 Gy for the
middle, the intermediate position and the end of the SOBP, respectively. This is somewhat less than that noted in
the first experiment for irradiations in the middle (13.0 Gy) and at the end of the SOBP (11.8 Gy) [1].
Notwithstanding this the ratio of doses between the middle and the end of the SOBP yield an RBE = 1.08 and this
is the same as that noted before – RBE = 1.10. A possible reason for the slight increase in radiosensitivity to the
proton irradiations is that a NMRI mice strain was used in this study compared to an ICR strain used in the first
set of readings.
The increase in RBE for the 200 MeV proton beam towards the end of the SOBP is consistent with biophysical
principles and reflects the increase in ionization density with lower proton energies. All readings were obtained
with in vitro methods. This increase is also in general agreement with whole-body irradiations carried out in the
SOBP [2]. However, increases in the RBE noted in these earlier experiments, which were also performed using a
7 cm SOBP, were somewhat less, at 7%. The greater increases obtained with the specialised set-up confirm the
need to perform the more complex irradiation of externalised intestinal tissue, and it is currently the only possible
way to map RBE variations in the critical SOBP dose zone.
References
1.
2.
J Gueulette, J P Slabbert, J Martinez, B de Coster, J Symons, J Nieto-Camero, and C Trauernicht,
iThemba LABS Annual Report 2007/08, 125.
J Gueulette, J P Slabbert, L Böhm, B M de Coster, J F Rosiera, M Octave-Prignot, A Ruifrok,
A N Schreuder, P Scalliet, D T L Jones, Radiotherapy and Oncology 61 (2001) 177.
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2.4.3 Estimating the / ratio for early responding tissue applicable to neutron therapy
M Zerabruk 1, J P Slabbert2, K Meehan3, J Gueulette4
1Cape
Peninsula University of Technology
LABS, Somerset West
3Centre of Excellence for Applied Research and Training, Abu Dhabi, UAE
4Molecular Imaging and Experimental Radiotherapy, Catholic University of Louvain, Belgium
2iThemba
Repair of sub-lethal damage is important in radiotherapy as it influences the physical dose applied when
changing the fractionation protocol. Experience with neutron therapy at iThemba LABS has shown that treatment
with more fractions and lower doses per fraction is beneficial for some patients. To calculate the iso-effective
treatment dose or to adjust the treatment dose in remaining fractions due to dosimetry errors, an appropriate /
ratio for neutrons is needed. Very little information for this is available and only for neutron energies different
from the beam at iThemba LABS.
In this work single and split dose experiments are performed to obtain data for iso-effective tissue responses.
Early tissue damage was quantified using histology sections of jejunum to count crypt survival. Split radiation
doses were applied 4 hours apart to allow full repair. Crypt stem cell survival data is shown for both 60Co gamma
rays as well as p(66)/Be neutrons – (Figure 1).
An / ratio of 11.5 Gy can be estimated for early tissue response using data obtained previously for the clinical
neutron beam at iThemba LABS. This is based on an / ratio of 7 Gy for crypt cell survival that was analyzed
using different fraction protocols with 200 MeV protons [1,2]. The estimated / is for an iso-effect of 10 crypts
per circumference regardless whether the treatment is with low- or high-LET radiation.
Calculating the biological effective dose for an acute treatment, the correctness of the estimated / ratio can be
tested against the observed results. The iso-effective dose calculated for an acute exposure of 8 neutron Gy, is
9.6 Gy for the split dose treatment. This compares to a value of 10.1 neutron Gy observed in the actual
experiment (Figure 1). For comparison the total dose needed to be given in 2 fraction treatment to be isoeffective to an acute photon dose of 13.1 Gy, is calculated to be 17 Gy. This compares to a value of 16.2 Gy
observed in the split dose readings made in this work.
Estimating / ratios for neutrons for different tissue types using data for X-ray and neutron treatments is the
only practical way to obtain such values. Additional histology analysis is ongoing to verify the fractionated
response for early reacting tissue.
98
Figure 1: Dose-effect relationships for crypt regeneration in mouse jejunum after one and two fraction exposures to cobalt-60 gamma rays
and p(66)/Be neutrons. Repair of sub-lethal damage is indicated by the increase in total dose to be iso-effective.
References
1.
2.
L Böhm, L S de Roubaix, D T L Jones and M Yudelev, NAC Annual Report, (1988) 126.
J Gueulette, J P Slabbert, L Böhm, B M de Coster, J Rosier, M Octave-Prignot, A Ruifrok, A N Schreuder,
A Wambersie, P Scalliet, D T L Jones, Radiotherapy and Oncology, 61 (2001) 177.
99
2.4.4 Using clinical findings to estimate the / ratio for acoustic neuroma
F J Vernimmen1, J P Slabbert2
1Department
2iThemba
of Medical Imaging and Clinical Oncology, University of Stellenbosch
LABS, Somerset West
Radiobiological modelling of the radiosensitivity and repair characteristics of specific target tissues is most useful
to decide possible therapeutic gain when using radiosurgery methods. In doing this an estimation of the / ratio
for a particular pathology can be obtained and knowing the extent of this variable is essential to calculate the
dose that needs to be applied.
In this work clinical data for a series of patient treatments for acoustic neuroma was examined. These patients
were treated according to different protocols. The data were analyzed to confirm earlier findings made using a
limited number of treatment protocols and hypo-fractionated stereotactic proton therapy [1]. Various treatment
protocols used by different investigators that proved to be iso-effective were examined according to the Tucker
model [2]. In this the difference in total doses Dn – Dm required to be iso-effective for n and m number of
fractions are related to the dose per fraction dn and dm applied. The slope of the line fitting the data in a plot of
Dn – Dm as a function of Dmdm – Dndn determines the / ratio for the iso-effect examined. An / value of
1.8 Gy is determined for acoustic neuroma. This is very similar to the value of 1.4 Gy estimated previously using
a fractionated equivalent plot. It is concluded that the / ratio for acoustic neuroma is indeed very small and
that they are best treated using radiosurgery or a hypo-fractionation protocol.
Figure 1: Total doses need to be iso-effective are compared when given in n and m number of fractions. Clinical data for the treatment of acoustic
neuroma with different treatment protocols are used to estimate a slope that is related to the / ratio for this radiosurgical target.
References
1.
F J Vernimmen, Z Mohamed, J P Slabbert, J Wilson, S Fredericks, iThemba LABS Annual Report 2007/
08, 127.
2.
S L Tucker, Int. J. Radiat. Oncol. Biol. Phys. 10 (1984) 1933.
100
2.4.5 Radiation-induced Apoptosis of Lymphocytes observed in a Cohort of 300 Donors
in the Western Cape
W Solomon1, K Meehan2, J P Slabbert3, N E A Crompton4, D Gihwala1
1Cape
Peninsula University of Technology
of Excellence for Applied Research and Training, Abu Dhabi, UAE
3iThemba LABS, Somerset West
4Cornerstone University, Michigan, USA
2Centre
The Leukocyte Apoptosis Assay developed by Crompton and Ozsahin [1] was used in this study to observe
radiation-induced apoptosis in a large population of donors in the Western Cape. The methodology used is
identical to that reported previously [2]. Radiation-induced apoptosis in a large population is needed to obtain
information that reflects variations between different individuals. A large number of donors are needed so as to
allow the calculation of z-scores [3] and to ascertain differences due to age and ethnicity. An analysis of z-scores
in a larger population allows one to identify radiosensitive and radioresistant populations. The aim of this study is
to obtain radiation- apoptosis data for CD4 and CD8 T-lymphocytes.
Percentage radiation-induced apoptosis in 300 healthy donors
45
Percentage radiation-induced apoptosis (%)
40
35
30
25
AVERAGE
20
15
10
5
0
0GyCD4
0GyCD8
2GyCD4
2GyCD8
8GyCD4
8GyCD8
Dose (Gy)
Figure 1: The average percentage apoptosis induced by 2 Gy and 8 Gy X-rays in CD4 and CD8 T-lymphocytes for 300 healthy donors.
The background (0 Gy) level of apoptosis is subtracted in each instance.
Figure 1 shows the average percentage of radiation-induced apoptosis for the 300 healthy donors (mean:
39.2 years, range 17-78 years) in CD4 and CD8 T-lymphocytes after 2 Gy and 8 Gy X-rays. A clear dose
response curve is observed as the percentage radiation-induced apoptosis increases with every dose of
radiation. The percentage apoptosis at 2-0 Gy for CD4 ranges from 1.0-23.65 with a mean of 6.86 and for CD8 it
ranges from 1.01-30.55 with a mean of 11.34. The percentage apoptosis at 8-0 Gy for CD4 ranges from 2.346.68 with a mean of 16.77 and for CD8 it ranges from 5.61-67.58 with a mean of 29.43. At each dose point,
there is a higher rate of apoptosis observed with CD8 lymphocytes when compared to that of the CD4
lymphocytes.
101
25
35
n = 300
r² = 0.3022
p = < 0.0001
a
20
b
30
CD8 2-0Gy8
0Gy CD8
25
15
10
20
15
10
n =300
r² =0.4710
P =< 0.0001
5
5
0
0
0
1
2
3
4
5
6
7
8
0
0Gy CD4
5
10
15
20
25
CD4 2-0Gy
80
c
70
CD8 8-0Gy
60
50
40
30
20
n = 300
r² = 0.5086
p = < 0.0001
10
0
0
10
20
30
40
50
CD4 8-0Gy
Figure 2: A comparison of the percentage apoptosis induced in CD4 and CD8 T-lymphocytes of 300 healthy donors. (a) CD4 and CD8
correlation for background(0 Gy) apoptosis; (b) CD4 and CD8 correlation after 2-0 Gy X-rays; and (c) CD4 and CD8 correlation after
8-0 Gy. Regression curves are shown as solid lines.
Background (0 Gy) apoptosis for CD4 and CD8 T-lymphocytes are presented in Figure 2a. Correlation values of
r2 = 0.3022 were observed with a p-value of <0.0001. For radiation-induced apoptosis of CD4 and CD8
T-lymphocytes after 2 Gy X-rays (Figure 2b), a correlation value of r2 = 0.4710 was seen with a p-value of
<0.0001. After 8 Gy X-rays (Figure 2c), a correlation value of r2 = 0.5086 was seen with a p-value of <0.0001.
The significant correlation between the CD4 and CD8 values for both 2 Gy and 8 Gy compares well with results of
Ozsahin et al. [4]. The study to obtain z-scores values that can be used to identify radiosensitive patients before
the commencement of radiotherapy continues.
References
1.
2.
3.
4.
N E A Crompton, M Ozsahin, Radiation Research 147 (1997), 55-60.
W L Solomon, K Meehan, J P Slabbert, N E A Crompton, D Gihwala, iThemba LABS Annual Report
2007/08, 133.
N E A Crompton, Y Shi, G C Emery, L Wisser, H Blattman, A Maier, L Li, D Schindler, H Ozsahin and
M Ozsahin, International Journal of Radiation Oncology Biology Physics 49 (2001) 547-554.
M Ozsahin, H Oszahin, Y Shi, B Larsson, F E Wurgler, N E A Crompton, International Journal of Radiation
Oncology Biology Physics 38 (1997) 429-440.
102
2.4.6 Flow Cytometric Detection of Bromodeoxyuridine as a Predictor of Cellular
Radioresistance
Z Dashi1, J P Slabbert2, M de Kock1
1Department
2iThemba
of Biosciences, University of the Western Cape, Bellville
LABS, Somerset West
A number of biological factors determine the response of tumours to radiotherapy. It is of interest to identify
radioresistant cell types as the treatment of tumours of this nature can benefit from neutron therapy. The inherent
cellular kinetics of a lesion results in different proportions of cells to be in different stages of the cell cycle and this
can influence the response to radiation treatment. Cells in the late S-phase of the cell cycle represent a
population that is very resistant to treatment with most types of ionising radiation.
A method was previously developed to read cells in S-phase using the flow-cytometer at iThemba LABS [1]. In
this method light scatter parameters and fluorescent signals from the laser beam of the flow-cytometer are used
to identify cells in different stages of the cell cycle. Cell cultures in exponential growth are pulse labelled with
5-bromodeoxyuridine (BrdU) and the S-phase fractions are identified using both a FITC labelled anti-body and
DNA histograms from staining with 7-AAD (7-amino-actinomycin-D). In this work the radioresistance of different
tumour cell lines were measured using clonogenic survival and related to S-phase content.
Two-colour flow-cytometric analysis for DU-145 (prostate ca.), HeLa (cervix ca.) and MCF-7 (breast ca.) cell lines
are shown is shown in Figure 1.
HeLa
Figure 1: Flow cytometry dot plots showing cells in different stages of the cell cycle. The large rectangular region show cells in the
S-phase. Circles show cells in G1 phase and G2 / M phase.
The survival curves for the three cells lines used in this study are shown in Figure 2. This for colony formations
following treatment with graded doses of 6 MV X-rays.
The mean inactivation dose for each cell type can be calculated from Figure 2, and is related to percentage cells
in the S-phase in Figure 3. It is evident that faster growing cell types with a higher fraction of cells in the S-phase
are more resistant to X-rays as reflected by larger mean inactivation dose values. These observations are
consistent with findings made using different cell types [2]. S-phase readings observed thus far vary over a
103
narrow range. For this reason radiosensitivity testing and S-phase fraction analysis are currently investigated for
different cell lines in order to confirm the relationship noted in Figure 3.
Figure 3: Mean inactivation dose values as a measure of
radioresistance to 6 MV X-rays for different cell types. This
is related to the percentage cells in the S-phase that could
be detected using flow cytometry.
Figure 2: Cell surviving fractions for different cell lines as a function of
dose following exposure to 6 MV X-rays.
References
1.
2.
Z Dashi, M de Kock and J P Slabbert, iThemba LABS Annual Report 2007/08, 135.
C Theron, J P Slabbert, A Serafin and L Böhm, Int. J. Radiat. Oncol. Biol. Phys. 37 (1997) 423.
104
2.4.7 Radiolabelling of his5-D-try6GnRH peptide with 123I for cell uptake and radiotoxicity
studies.
D G Achel 1, M T Madziva2, D D Rossouw3 and J P Slabbert3
1Applied
Radiobiology Centre, Radiological and Medical Sciences Research Institute, Ghana Atomic Energy
Commission, Legon, Ghana.
2Institute of Infectious Disease and Molecular Medicine, University of Cape Town
In view of non-specific toxicity of most chemotherapeutic agents against normal cells, the development of
targeted chemotherapy is warranted.
The therapeutic benefit of Auger electron emitters has long been
recognised by investigators [1,2]. These particles are characterised by a highly localised distribution of electrons
resulting in energy depositions in cellular DNA within a sphere of nanometre dimensions. This causes high-LET
radiation damage with an efficiency similar to that of -particles.
123I
is particularly attractive for use in Auger
electron therapy as the half-life of the isotope is only 13.2 hours.
More than 80% of ovarian and endometrial cancers and over 50% of breast cancers express the gonadotropin
releasing hormone receptors GnRH-R. GnRH-R is therefore a suitable target for tumour specific gene therapy
[3]. Gonadotropin Releasing Hormone (GnRH) involvement in several carcinomas has also been demonstrated
[4]. For these reasons a peptide specific to this has been labelled with
123I.
Human Embryonic Kidney (HEK)
cells are known to have GnRH receptors and these were used to evaluate radiobiological damage.
Binding of the decapetide (his5-D-tyr6-GnRH) to GnRH receptors after a two-hour incubation is shown in Figure 1.
Specific binding of the radioligand and an affinity of cell surface receptors for the radiopharmaceutical [ 123I]GnRH
are evident and reflect the high radiochemical purity obtained using HPLC purification methods. The affinity
constant for the binding of [123I]GnRH to cell surface receptors, as well as the number of binding sites, was
however not evaluated. This is under investigation. Cell samples labelled with the
123I-peptide
and left for 16
Figure 1: Radioactivity counts showing binding of 123I-peptide to gonadotropin releasing hormone receptors (GnRH-R) to human
embryonic kidney cells. Control readings are shown for [123I]NaI.
105
hours to accumulate decays of the isotope have also been examined for cellular radiation damage. Micronuclei
formation for this treatment is shown in Figure 2. It is concluded that the bioactive [123I]GnRH is a promising
radiopharmaceutical for radionuclide therapy.
Figure 2: Micronuclei counts following binding of [123I]GnRH to gonadotropin releasing hormone
receptors of Human Embryonic Kidney cells.
References
1.
2.
3.
4.
P Haefliger , M Agorastos, A Renard, G Giambonini-Brugnoli and R Alberto, Bioconj. Chem. 16 (2005)
582.
L Bodei, A L Kassis, S J Adelstein and G Mariani, Cancer Biotherapy and Radiopharm 18 (2003) 861.
C Gründker, A H Nia and G Emons, Mol. Cancer Ther. 4 (2005) 225.
A Stragelberger, A V Schally and B Djovan, Eur Urology 3 (2008) 890.
106
2.4.8 Optimization of cell sample preparation methods and classifier parameters to
allow real time analysis of microscope images to detect radiation damage
L August1, P Willems2, A Vral2, B Thierens2, J P Slabbert3
1Department
of Bio-Medical Sciences, University of Western Cape
of Basic Medical Sciences, Ghent University, Belgium
2Department
Experimental work is ongoing to set up an automated microscope that is equipped with a real time image analysis
system. The microscope system is currently in the Department of Basic Medical Sciences, at Ghent University,
Belgium. This instrument is funded by a grant from the Flemish Inter-University Council (VLIR) to help South
Africa implement a routine bio-monitoring service for radiation workers. The main objective of this project is to
automate a Metafer system that will allow the detection of micronuclei in large numbers of T-lymphocytes that is
used as a biomarker of radiation damage. The system consists of a Zeiss Axio-lmager microscope equipped with
a Märzhäuzer motorised scanning stage, a CCD camera and Metafer4 image analysis software (Figure 1).
Figure 1: The automated image analysis system.
Using standard staining methods, image classifier parameters could be set to detect binucleated cells and
micronuclei but some errors occur [1]. An analysis of cell detection errors and incorrect micronuclei readings
showed that these are caused by inconsistent shape and granularity of cell cytoplasm (Figure 2). To eliminate
misclassification of cells, different cell culture methods and staining techniques have been investigated. Wholeblood cells were cultivated for a total of 70 hours. The spindle fibre inference agent cytochalasin B was added at
24 hours and multiple cell fixation steps were applied. Staining with DAPI and generating fluorescence signals
using band filters in the ultraviolet region result in more accurate detection of binucleated cells and micronuclei.
107
Figure 2: Human lymphocytes isolated from whole-blood cell samples and cultured to show radiation damage. Giemsa stained cells are
shown on the left. On the right are T-lymphocytes from whole-blood cultures and stained with acridine orange. Misclassification of cells
is less frequent when prepared as shown on the right and stained with DAPI.
A series of experiments has been performed to systematically analyse the influence of each classifier parameter.
This is listed in Table 1. With a better understanding on how to set up cell classifier values for automated
microscopic analysis, tests are now ongoing to validate the Metafer system. Working with whole-blood cultures
and staining cells using the DNA stain DAPI with anti-fade, result in a high level of accuracy in detecting
micronuclei. An example is given in Figure 3. Here the classifier set-up allowed the processing of a gallery of
images in which the micronuclei in only one cell has been incorrectly counted.
Figure 3
108
Characteristic
Influence when using DAPI Stain of Whole-blood cultures.
Nuclei:
1. Object threshold
Not too critical to identify binucleated cells (BNC‟s).
2. Minimum area (m2)
Cells from whole-blood cultures three times larger than isolated cells. Minimum
3. Maximum area (m2)
and maximum areas increased to include the maximum number of cells.
4. Maximum relative
Not critical. Shape of a BNC does not affect the detection of micronuclei and
concavity depth
number of misclassified BNC‟s not significant.
5. Maximum aspect ratio
6. Maximum distance
between nuclei (m)
7. Maximum area
Visual inspection showed that nearly all BNCs are still touching, but a value
below 18m excluded too many large cells from analysis.
A value of 80% yield good results.
asymmetry
8. Region of interest
radius (m)
9. Maximum object area in
Keeping the values of both parameters at 30 m allow detection of most
scorable cells. Surrounding cells did not affect the accuracy on micronuclei
detection.
ROI (m2)
Micronuclei:
1. Object threshold
Difficult to optimize to exclude background “noise” yet to detect faint micronuclei.
2. Minimum area (m2)
Included pinpoint micronuclei.
3. Maximum area (m2)
Area need to be increased to accommodate larger cells form whole-blood
cultures.
4. Maximum relative
concavity depth
Difficult to optimize to exclude cell debris as slide appearance differs from batch
to batch.
5. Maximum aspect ratio
6. Maximum distance (m)
Not critical. Well-defined criteria for micronuclei will exclude most of other cells.
Table 1: Cell classifier parameters that have been optimized to accurately detect and count binucleated cells and micronuclei.
Parameters are for DAPI-stained lymphocytes following whole-blood cultures.
Reference
1.
L August, A Vral, P Willems, J P Slabbert and B Thierens, iThemba LABS Annual Report 2007/08, 143.
109
2.4.9 The development of a pan-centromeric probe used in assessing cellular damage
from low doses of ionizing radiation.
A Baeyens1, R Swanson1, J P Slabbert1, P Willem2, A Vral3
1iThemba
LABS, Somerset West
of Haematology and Molecular Medicine, WITS Medical School
3Department of Histology, Medical Basic Sciences, University of Ghent, Belgium
2Department
New methods are investigated to quantify residual radiation damage in radiation workers. This is part of the BioMonitoring project funded by the Flemish Interuniversity Council (VLIR). Improving the low dose limit that can be
detected with micronuclei formations in lymphocytes is particularly important as semi-automated equipment to
scan such samples is now available.
Micronuclei, small nuclear fragments in the cytoplasm of interphase cells, are the result of breaks in the DNA.
Two types of micronuclei can be distinguished from each other using fluorescence in situ hybridization (FISH) of a
pancentromeric DNA probe. Centromere-positive micronuclei represents an entire chromosome that is mostly
derived from spontaneous damage. The centromere-negative micronuclei represents chromosomal fragments.
Almost all micronuclei induced by radiation are centromeric negative (Figure 1).
Figure 1: The formation of micronuclei through different mechanisms and the use of FISH methods with a pan-centromeric probe to
determine this.
The pan-centromeric probe can be used to differentiate between micronuclei induced by low doses of radiation
and that from the background-micronuclei found in normal unexposed individuals. Although commercial pancentromeric probes are available it is more feasible to make an in-house probe. Principally, it is relatively
inexpensive to produce and thus makes it affordable for use with large numbers of samples from radiation
workers.
In this study, we make use of two different methods to create an in-house pan-centromeric probe. The first
utilises a human DNA sequence clone called p82H, and the second involves making a synthetic probe from
human DNA with primers designed to target the centromeres.
110
P82H is a 2.4 kb human DNA sequence and is a member of the alphoid repeated sequence family. The p82H
clone hybridises to the centromeres of all chromosomes. The p82H plasmid was grown in Escherichia coli and
extracted using a plasmid extraction kit. Thereafter it was labelled via nick translation, and used as a FISH probe.
Several attempts were made to optimise this method but satisfactory results could not be obtained. For this
reason a second method was employed that involves the making of a synthetic probe that is amplified from
human DNA with polymerase chain reaction (PCR) methods, and primers designed to target centromeres. Male
DNA was used to obtain X, Y and autosomal centromeres. The PCR product was then purified and labelled via
standard nick translation and used as a FISH probe.
The probes prepared using this methodology bind to centromeres of all the chromosomes and can be visualised
using fluorescent microscopy (Figure 2). As a result of this the probe also binds with chromosomes within the
main nucleus of a cell in interphase. This is used as a control to confirm that hybridisation has occurred. Very
good results have been obtained using this method (Figure 3).
Figure 2: A metaphase spread that shows the probe to be highly specific to the centromeric region of a chromosome and binds to this
area of all chromosomes.
Figure 3: Binucleated lymphocytes with a single micronucleus. The micronuclei in the cell on the left show two positive signals for
a centromeric region. The micronuclei in the cells on the right are acentric in nature and the result of ionizing radiation.
The probe can be used to determine clastogenic and aneugenic events that occur as induced or spontaneous
events in individuals. Further studies are in progress to determine background levels of micronuclei in healthy
males and females and the use of the probe to identify them as centromere-negative and centromere-positive.
111
2.4.10 Induction of dicentrics and rings in lymphocytes exposed to Neutrons and X-rays
N Ait Said1, Z Lounis-Mokrani1, J P Slabbert2, M Marx3
Centre de Recherche Nucléaire d‟Alger, Algeria
iThemba LABS, Somerset West
3 Department Human Genetics, University of Stellenbosch
1
2
Biophysical models of radiation action are based on simple linear or linear-quadratic dose-response relationships
[1]. They were proposed to explain the formation of radiation-induced exchanges such as dicentrics, rings and
translocations. Radiation induced unstable chromosome aberration frequency (dicentrics and centric rings) in
peripheral blood lymphocytes is a powerful tool for studies that compare low-LET (X-rays) and high-LET (neutron)
radiation effects [2]. From the observed frequency of unstable chromosome aberrations, it is interesting to
evaluate the F ratio. Several studies have demonstrated that exchanges frequently involve the interaction of
three (or more) damaged sites distributed among two (or more) chromosomes. It is important to understand the
mechanism by which aberrations are produced by radiation, and to compare between those aberrations such as
dicentrics and rings due to neutrons, and those due to X-rays. In order to evaluate the F ratio induced in
lymphocytes, we have exposed blood samples respectively to p(66)/Be neutrons and 6 MV X-rays at iThemba
LABS‟ irradiation facilities.
Heparinized whole blood from the same healthy 48-year old male was used for all the irradiations. After
exposure, enzymatic repair processes take place and lead to the formation of chromosomal aberrations. Whole
blood cultures were set up applying a special method to obtain elongated chromosomes. Slides were stained
with Giemsa to analyze induced chromosome aberrations. Dicentrics and centric rings were scored in well
spread metaphases with 46 centromeres using conventional cytogenetics. The preliminary set of results obtained
after microscope analysis are shown in Figures 1 and 2.
Figure 1. Dose-effect relationship for 6 MV X-rays
Figure 2. Dose-effect relationship for p(66)/Be neutrons
112
As expected, the frequency of dicentrics per cell increases when dose increases with both neutrons and X-rays.
Also, higher frequencies of aberrations are noted for neutrons compared to X-rays. However, before F-ratios can
be determined more metaphases need to be analysed. Complex exchanges necessitate more investigations
about the mechanisms underlying the formation of chromosome aberrations. For this reason Fluorescence In
Situ Hybridization (FISH) techniques are also investigated to quantify stable chromosome translocations
frequencies.
References
1.
2.
ICRP, 1990 Publication 60, Annals of the ICRP, 21 (1991), Pergamon Press, Oxford.
E Schmid, D Regulla, S Guldbakke, D Schlegel and M Roosc. Radiat. Res.157 (2002), 453–460.
2.4.11 Use of CR-39 track detectors to investigate microdosimetric changes in the
spread out Bragg peak region of a proton therapy beam
N Z Lounis-Mokrani1, M Aitziane1, D Imatoukene1, A Badreddine1, M Mezaguer1, J P Slabbert2, J Nieto-Camero2,
J Symons2 and J Gueulette3
1Nuclear
Research Center of Algiers, 2 Bd Frantz Fanon BP 399, Algeria.
LABS, Somerset West.
3Université Catholique de Louvain, Bruxelles, Belgium.
2iThemba
For therapy applications it is important to specify the quality of a proton beam in terms of physical and biological
characteristics. Microdosimetric investigations can provide information on the spatial and temporal distribution of
absorbed energy and consequently on the distribution of cellular damage. The RBE is not constant in all
positions along the spread out Bragg peak (SOBP) [1]. To understand this better, ionization density effects in a
solid state detector were observed. This was done since previous experience with a polyallyl diglycol carbonate
detector (CR-39) proved to be most informative [2,3].
The interaction of charged particles with C, O and H in the detector creates a high density damage region around
the trajectory. These damaged regions were observed using optical microscopy after an etching process in an
alkaline solution. Morphologic parameters of the observed tracks can be related to the characteristics of incident
particles and constitute an important tool for microdosimetric studies [4].
In this study, we investigate the track structure distribution in a 7 cm SOBP for the proton therapy beam at
iThemba LABS. Sixty CR-39 detectors of 500 µm thickness have been stacked tightly to form one block
interfaced by three 6 mm PPMA slides (Figure 1).
The stack of detectors is mounted behind Perspex plates in order to cover the entire 7 cm SOBP (Figure 2).
Irradiations using 200 MeV protons were performed to a dose of 2 Gy using a dose rate of about 3.8 Gy/min.
Track revelations have been made using 6.25 N KOH solution at 60°C for 3 hours. Samples are being assessed
using an optical microscope fitted with a Quantimet 500 image analyzer system.
113
Figure 2: CR-39 detectors positioned to cover the SOBP
region.
Figure 1: A stack of sixty CR-39 detectors exposed to
200 MeV protons.
Figure 3: Track etch structures in a CR-39 detector following exposure to 200 MeV protons. The frequency distribution for different track
areas is shown on the right.
Track density readings as a function of depth in the SOBP region of the 200 MeV proton beam is currently
evaluated. This to compare with radiobiological data that is currently being analyzed for the same proton therapy
beam.
References
1.
2.
3.
4.
J Gueulette, J P Slabbert, B M de Coster, D T L Jones and A Wambersie, Protons, Ions and Neutrons in
Radiation Oncology International Symposium, Munich (Germany), (2007).
Z Lounis-Mokrani, A Badreddine, D Mebhah, D Imatoukene, M Fromm and M Allab, Radiation
Measurements 43 (2008) S41.
Z Lounis-Mokrani, M Fromm, A Chambaudet and M Allab, Radiation Measurements 36 (2003) 615-620.
Z Lounis-Mokrani, S Djeffal, K Morsli and M Allab, Nuclear Instruments and Methods in Physics Research
179 (2001) 543.
114
2.4.12 Development of a Sterile Insect Technique for the Commercial Control of False
Codling Moth, Thaumatotibia leucotreta Meyrick (Lepidoptera: Tortricidae)
J H Hofmeyr 1, M Hofmeyr 1, S Bloem 2, J Carpenter 3 and J P Slabbert 4
1Citrus
Research International, Citrusdal
Atomic Energy Agency, Vienna, Austria
3United States Department of Agriculture, ARS, Georgia, USA
2International
False codling moth (FCM) is indigenous to Southern Africa and the pest infests many different deciduous,
subtropical, and tropical plants. FCM is currently not present in the United States. Many U.S. Federal and State
Agencies have expressed concern that this pest could soon be introduced into the USA, as a direct result of
increased international trade and tourism between the United States and South Africa. FCM has documented
resistance to various insecticides commonly used for its control. Other suppression strategies with pheromones,
pathogens, predators and parasitoids have had limited success and cannot be used as stand-alone tactics. To
prevent FCM from entering the United States, a sterile insect technique (SIT) programme for FCM was initiated to
function as an area-wide pest management tactic in South Africa.
The first part of this programme was to establish radiation doses needed for SIT applications. Suitable irradiation
containers were developed and test samples were irradiated using a Cobalt-60 source. For this extensive
chemical dosimetry readings were used to determine the optimal levels of radiation doses that are required.
Readings are based on internationally acceptable molecular yield values and an extinction coefficient determined
for a UV spectrophotometer at iThemba LABS. FCM male and female mature pupae and newly emerged adults
were treated with 50 Gy incremental doses of gamma radiation (0-350 Gy) and then either inbred or out-crossed
with fertile counterparts (Figure 1). For newly emerged adults, there was no significant relationship between dose
of radiation and insect fecundity when untreated (N) females were mated to treated (T) males (N♀ by T♂).
Figure 1. Fertility of False Codling Moth irradiated with incremental doses of gamma irradiation
115
However, fecundity of treated females mated to either untreated (T♀ by N♂) or treated males (T♀ by T♂)
declined as the dose of radiation increased. A similar trend was observed when mature pupae were treated. The
dose at which 100% sterility was achieved in treated females mated to untreated males (T♀ by N♂) for both
adults and pupae was 200 Gy. In contrast, newly emerged adult males treated with 350 Gy still had a residual
fertility of 5,2% when mated to untreated females and newly emerged adult males that were treated as pupae had
a residual fertility of 3,3%. Inherited effects resulting from irradiation of parental (P1) males with selected doses of
radiation were recorded for the F1 progeny. Decreased F1 fecundity and fertility increased F1 mortality during
development, and a significant shift in the F1 sex ratio in favour of males was observed when increasing doses of
radiation were applied to the P1 males. The radiation biology research is now followed by orchard field cage
experiments.
116
2.5 Materials Research Group
2.5.1 Thin film thickness measurement and depth profiling using Heavy Ion - ERDA
M Msimanga1,2, C Pineda-Vargas1, S Murray1, C M Comrie2
1iThemba
LABS, P O Box 722, Somerset West, 7129 South Africa
of Cape Town, Rondebosch 7701, South Africa
2University
Thin film materials play an important role in many established and emerging technologies, for example in
components for electronic materials, hard and protective coatings and sensor development in nanotechnology [1].
The physical properties of such materials are directly linked to their thin film structuring and composition. The
problem of quantitative and sensitive analysis of light elements in thin films has been found to be best addressed
by nuclear analytical techniques using ion beams from particle accelerators [1]. Of the most widely used ion
beam analysis techniques, Heavy Ion – Elastic Recoil Detection Analysis (HI – ERDA) stands out as the most
suitable for the analysis of light elements. A Time of Flight – Energy spectrometer has been developed and
assembled [2] at iThemba LABS for applications in Heavy Ion – ERDA, developed as a complimentary technique
to the existing RBS and PIXE nuclear analytical techniques.
This presentation describes first test measurements performed to determine the thickness, depth profile and
impurity content of a refractory layer of calcium fluoride deposited on a silicon substrate. The calcium fluoride
was deposited by electron beam evaporation at a base pressure of about 10-6 mbar. The analysis was carried
out using a beam of 27.5 MeV Kr15+ projectile ions incident at an angle of 15° to the sample surface. Coincidence
measurement of the time of flight and energy of recoils from the target sample made possible separation of these
ions according to atomic mass. Figure 1 shows a 2D Time of Flight – Energy coincidence contour plot of recoils
from the target, and the resultant elemental depth profiles measured from the surface inward.
(b)
(a)
Figure 1: A 2-D coincidence scatter plot of the time of flight (ToF) and energy (E) of recoils from a CaF/Si sample (a) and elemental
depth profiles extracted from the individual ToF spectra (b).
117
Energy (MeV)
The depth profiles, calculated using KONZERD [3],
30
show a marked deviation from the expected Ca:F
stoichiometric ratio of 1:2. The stoichiometry varies
0.5
25
1.0
1.5
2.0
experiment
F
layer.
The
concentrations
oxygen
were
and
found
carbon
to
be
impurity
constant
throughout the whole layer. The thickness of the
film, deduced from the point at which the Ca and F
Normalized Yield
with depth, averaging Ca0.4F0.5 in the bulk of the
simulation
20
15
Ca
10
relative concentrations both fall below 0.1 at the
5
interface with the substrate, was measured to be
0
100
(740 ± 40) x 1015 at/cm2 or 210 ± 10 nm.
200
300
400
500
600
Channel
Figure 2 shows the result of a comparative
measurement performed using the more established
Figure 2: RBS energy spectrum of the CaF\Si sample obtained
using 2 MeV helium ions, showing Ca and F peaks. The C and O
impurities peaks are buried in the Si substrate signal.
RBS technique. The RBS measurement gave a thickness value of 750.0 x 1015 at/cm2 (212 nm). While both
techniques give comparable layer thickness, only HI – ERDA can provide elemental depth profiles because
coincidence measurement of Time of Flight and Energy allows for the separation of different atomic species with
similar energies from the target layer. It is also only in HI – ERDA that the oxygen and carbon impurities signals
can be obtained separately from the interference of the silicon substrate signals.
Acknowledgements
The authors would like to thank Professor G Dollinger and Dr A Bergmaier both from the UniBw, Munich,
Germany, for their help during measurements and data analysis.
References
1. N Dytlewski, Improvement of the reliability and accuracy of heavy ion beam nuclear analytical techniques,
IAEA Coordinated Research Project F11013 (2007).
2. M Msimanga et al., Nucl. Instr. and Meth. B. 267 (2009) 2671.
3. A Bergmaier, G Dollinger, C M Frey and T Faestermann, Fresenius J Anal Chem 353 (1995) 582.
118
2.5.2 An investigation into enigmatic textures developed along plagioclase-augite grain
boundaries at the base of the Main Zone, Northern Limb, Bushveld Complex
F Roelofse1, L D Ashwal2, C A Pineda-Vargas3, W J Przybylowicz3
Council for Geoscience, Private Bag X112, Pretoria, 0001, South Africa
School of Geoscience, University of the Witwatersrand, Private Bag 3, WITS, 2050, South Africa
3 Materials Research Group, iThemba LABS, P O Box 722, Somerset West, 7129, South Africa
1
2
An enigmatic texture in which orthopyroxene exsolution lamellae within clinopyroxene protrude into adjacent
plagioclase crystals occurring in a gabbromorite from the base of the Main Zone of the Bushveld Complex was
investigated petrographically, by electron microprobe and by the nuclear microprobe located at the Materials
Research Group of iThemba LABS. Grain boundaries exhibiting said texture show an increase in the An-content
of plagioclase as the grain boundary is approached from the plagioclase side, coupled with an increase in the
magnesium number of clinopyroxene as the grain boundary is approached from the clinopyroxene side. PIXE
elemental maps were able to resolve the zonation in Ca and Si in plagioclase along affected grain boundaries,
coincident with the well-known plagioclase substitution reaction CaAl  NaSi (see Figure 1).
The texture was interpreted as representing the crystallization products from a newly intruded melt into a nearly
solidified crystal mush, which initially gave rise to the lengthening and broadening of pre-existing orthopyroxene
exsolution lamellae within clinopyroxene, followed by crystallization of plagioclase richer in An-component and
clinopyroxene with higher Mg# adjacent to the lengthened and broadened orthopyroxene exsolution lamellae.
Figure 1: (Left) Back-scattered electron image showing variation in plagioclase An% and clinopyroxene Mg# along a grain boundary
exibiting the texture. (Right) : PIXE elemental map for Ca with An% of plagioclase (white) and Mg# of clinopyroxene (black) from a line
profile conducted using the NMP superimposed.
119
2.5.3 The effect of electroless plating bath conditions in the elemental distribution of Pd,
Pt, Ag and Cu layers deposited on the surface of AB5-type metal hydride alloys for
hydrogen storage.
M Williams1, A Nachaev2, C A Pineda-Vargas2
South African Institute for Advanced Materials Chemistry, Department of Chemistry, University of the Western
Cape, Private Bag X17, Bellville, 7535, South Africa
2 Materials Research Group, iThemba LABS, P O Box 722, Somerset West, 7129, South Africa
1
To improve the deposition of Pd layers deposited on the surface of rare earth AB5-type metal hydride alloys the
technique of surface modification with 1% vol gamma-APTES pre-treatment was used [1]. Dynamic analysis in
micro-PIXE using the software package GeoPIXE II [2], was conducted to study qualitatively the surface
distribution of Pd layers deposited on the surface of metal hydride alloys using NaH 2PO2-based and N2H4-based
electroless plating bath conditions. In addition two metals were also deposited sequentially and co-deposited.
It was confirmed that a discontinuous Pd layer was deposited on the surface of the AB5-type alloy after treatment
in a N2H4-based Pd electroless plating bath. In comparison, a similar type of discontinuous Pd-P coating was
observed on the surface of the AB5-type alloy after treatment in a NaH2PO2-based Pd electroless plating bath. It
was thus concluded that the current plating conditions did not facilitate the deposition of continuous Pd layers.
It was previously confirmed that the AB5-type alloy surface-modified without functionalization did not facilitate the
surface deposition of continuous layers of Pd, and that the Pd particles were scattered. In contrast, dynamic
analysis
confirmed
that
the
AB5-type
alloys
surface-modified
after
functionalization
in
-aminopropyltriethoxysilane, supported continuous layers of Pd-P.
Deposited Ni could not be separated from the background matrix, which was mostly constituted of Ni surface
clusters. Discontinuous layers were observed for all the sample alloys surface-modified using palladium mixedmetal coatings. Isolated clusters of Pd, Cu, Pt, and Ag were observed, illustrating the inability to produce
continuous layers on the surface of the alloy.
References
1. C G Ryan, D R Cousens, Geo-PIXE II Quantitative PIXE trace element analysis and imaging. CSIRO
Exploration and Mining, North Ryde, NSW 2113, Australia, 2002.
2. M Williams, M Lototsky, A Nechaev, V Yartys, J Solberg, C A Pineda-Vargas, Q Li and V Linkov. iThemba
LABS Annual Report (2007/8) 155.
120
2.5.4 Effect of annealing on scratch resistance and morphology of vanadium-platinum
multilayer systems.
M Topić1, G Favaro2, C A Pineda-Vargas1, R Bucher1, C I Lang3
Materials Research Group, iThemba LABS, P O Box 722, Somerset West, 7129, South Africa
CSM Instruments, Switzerland
3 Centre for Materials Engineering, University of Cape Town. Private Bag, South Africa
1
2
It is well known that physical and mechanical properties play an important role in applications of pure metals and
their alloys in various industrial fields. However, Pt and V as the metals of our interest are soft in their pure
states. The bulk alloying is one possibility to enhance the mechanical properties. It has been shown that the
surface hardness can be increased by a factor of 6 by alloying of pure Pt with Co or Cu (up to 15 at%) [1-3].
However, the process of bulk alloying has significant limitation in the Pt-V system; an addition of above 11 at%V
increases the strength and surface hardness significantly and therefore, the manufacturing of the components by
severe plastic deformation becomes very limited. An alternative way of improving the surface properties such as
hardness and scratch resistance is to make use of coated systems and thus, our interest in the effect of multilayer
V/Pt coatings on scratch resistance and morphology of single Pt and double coated systems (Pt and V layers).
Vanadium coupons (10x10x1 mm) were used as substrates and were mechanically polished to approx. 0.1 m
surface roughness. Pure platinum and vanadium (99.99 wt%) were deposited by the electron-beam evaporation
method. The coatings were deposited at room temperature under high vacuum conditions, 5 x10-4 Pa, using a
current of 30 mA and a deposition rate of 4 Å/sec. Two coated systems were studied: a single Pt layer (0.3 m)
and a system consisting of two layers (0.3 m Pt and 0.2 m V) both deposited on thick vanadium substrates.
Both systems were subsequently annealed at 700C for 45 minutes under vacuum conditions. The effect of
annealing on scratch resistance of coatings was determined by the CSM Nano-Scratch Tester. The X-ray
diffraction technique (BRUKER ADVANCE-8) was used for the identification of various Pt-V phases. The coating
morphology was studied by scanning electron microscopy (Cambridge Stereoscan 200X). The elemental
distribution of Pt and V was mapped using proton induced X-ray emission technique.
Comparative results of as-deposited coatings show that the critical load (14.83 mN) measured in the single layer
system is slightly lower than the critical load at which the double layer system fails (15.44 mN). More importantly,
the scratch resistance of both systems was significantly improved by the annealing process: critical loads of
27.94 mN and 24.87 mN were measured in single Pt (0.3 m) layer and double (0.3 m Pt_0.2 m V) coated
systems respectively. The scratch resistance of a single layer system was slightly better than the resistance of a
double coated system; the additional V layer could possibly be the reason for such behaviour. The phase
analysis of both coated systems indicates the presence of two phases, PtV and the vanadium rich (PtV 3) phase.
Improved scratch resistance is attributed to phase formation caused by annealing treatment.
The Pt (L line) map (Figure 1a) shows that the concentration of Pt varies across the surface of the annealed
double layer system. The calculated concentration variation between 50% and 70% indicates that different
phases have been formed as a consequence of annealing treatment. The presence of PtV and PtV 3 phases was
121
confirmed by X-ray diffraction. However, the V map (Figure 1b) reflects the overall V-concentration due to the
high penetration of protons on the sample‟s surface. Therefore, the X-rays were collected from both substrate
and top coating layer so that they cannot be directly correlated with the formation of phases.
Figure1: PIXE maps showing the elemental distribution of Pt (a) and V (b) of the double layer system subjected to
annealing at 700C for 45 min
References
1. S Nxumalo, M P Nzula, C I Lang, Materials Sci. Eng. A 336 (2007) 445-446.
2. M Carelese, C I Lang, Scripta Materialia 54 (2006) 1311.
3. T Biggs, S Taylor, E van der Linden, Platinum Metals Rev. 49 (2005) 2.
2.5.5 Scratch Resistance of Platinum Coatings
M Topić1, G Favaro2, R Bucher1, C I Lang3
iThemba LABS, P O Box 722, Somerset West 7129, South Africa
Instruments, Peseaux, Switzerland
3 Department of Mechanical Engineering, University of Cape Town, Rondebosch 7700, South Africa
1
2 CSM
The platinum-coated systems are used in many applications where the surface properties, such as scratch
resistance, surface hardness and electrochemical activity, play an important role [1,2]. However, our particular
research interest was focused on scratch resistance of Pt-V coated systems. We investigated the effect of
coating thickness and annealing parameters on scratch resistance of both single and double layer coatings.
Two systems have been studied: i) single Pt layers (thickness of 0.1 m and 0.3 m) deposited onto
V substrates, and ii) a double coated system consisting of Pt (0.1 m) and V (0.2 m) layers also deposited on
1 mm thick V substrate. The coatings were deposited by electron-beam deposition and afterwards annealed at
700°C under vacuum conditions for 45 minutes. The coating morphology has been studied by scanning electron
microscopy while the phase analysis were performed using X-ray diffraction. The patterns were collected at
diffraction angles of 2=20-100° using CuK radiation with measurements of 0.03° step size. The scratch
resistance was determined by nano-scratch tests using a diamond indenter with an initial load of 0.3 mN and
122
40 mN as a final load. The critical load at which the coatings were deliminated was measured in progressive-load
mode over a total scratch length of 4 mm.
The SEM study revealed that the annealing process changed the coating morphology and surface roughness
while the phase analyses (Figure 1) show that two phases, PtV and PtV3 have been formed in both single and
double layer annealed coatings. Considering the scratch resistance of as-deposited single systems, it was found
that the critical load depends on coating thickness, being better for a thicker Pt layer. Furthermore, the scratch
resistance of double coated systems was slightly better in comparison to single Pt coated systems, see Figure 1.
However, the annealing treatment and subsequent formation of Pt-V phases improved the scratch resistance of
both systems used in this study. The highest critical load was determined in a thicker single Pt system indicating
that the Pt availability has significant effect on scratch resistance. However, the comparison between single and
double systems having the same thickness of Pt layer (0.1 m) shows a higher critical load in double coated
systems which might be attributed to the presence of the second layer.
The study on Pt-V coatings shows that the scratch resistance of the systems is affected by two factors: thickness
of deposited layers and annealing treatment.
Figure 1: X-ray diffraction patterns of Pt-V coatings and (right) schematic presentation of scratch resistance.
References
1. S Nxumalo, M P Nzula, C I Lang. Mat. Sci. Eng. A 336 (2007) 336-340.
2. D Haridas V Gupta K Sreenivas. Bull. Mater. Sci. 31 (2008) 3.
123
2.5.6 An X-ray scattering study of Pt1-xVx alloys
A Gibaud1, M Topić2, G Corbel3, C I Lang4
1 School
Laboratoire de physique de l‟état condensé, UMR-CNRS 6087, Université du Maine, Le Mans, France
3 Laboratoire des oxydes et fluorures, UMR-CNRS 6010, Université du Maine, Le Mans, France
4 Department of Mechanical Engineering, University of Cape Town, 7701 Rondebosch, South Africa
2 iThemba
Platinum and platinum alloys are highly valued in jewellery, electronics and optical applications. In all these fields,
it is of fundamental importance to know as accurately as possible the chemical composition of these precious
materials.
The increasing monetary value of precious metals justifies the high precision demanded for
measurement of fineness. The X-ray fluorescence method is quick and accurate but measures the near-surface
composition, requiring a homogeneous alloy. The other techniques, being destructive, are of little practical
interest. However, the X-ray scattering technique offers determination of the lattice parameter for solid solutions
to high precision. The effect of V concentration on the lattice parameter and density of PtV alloys (1 at.%; 5 at.%;
7.5 at.%, 11 at.% V) was studied using X-ray scattering.
The XRD patterns of Pt-V alloys and the effect of V concentration on their lattice parameters are shown in Figures
1 and 2. Rietveld analysis was used to determine lattice parameters with a very good accuracy. The lattice
parameter of the Pt fcc phase strongly decreases with the increase in V solute concentration. In the range from
0 at.% to 11 at.% the decay is quite linear and the data fit yields a variation of the lattice parameter with the
V concentration x, expressed in percent, as a(nm)  0.39275  2.37 x10 4 x . As the crystal structure of V
differs from that of Pt, this linear decay cannot stand over the whole range of concentrations as shown by the
dotted line in Figure 2, and the line accordingly does not pass through the value of the V lattice parameter. This is
also the reason why the Vegard's law [1,2] cannot be fulfilled over the whole range of concentration in the
platinum-based solid solution. From the lattice parameter measurements of the pure metals we were able to
derive the radii of the Pt and V atoms. If we assume that the packing factors of Pt and V atoms are 0.74 and 0.68,
the radii of their atoms are RPt=0.1389 nm and RV=0.1311 nm. The V atoms are therefore only slightly smaller
than the Pt ones. As a consequence we can infer that a solid solution will be observed at low concentrations. This
is indeed the case at room temperature in the range of concentration we have studied. Since the radius of V
atoms is smaller than that of Pt, the lattice parameter decreases when x increases.
However, if we extend the straight line up to the 100% concentration we end up with a lattice parameter of
0.371 nm. This value is in full agreement with the lattice parameter obtained what could be derived from the fcc
packing and the radius of vanadium. Additionally, it is possible to show that the slope (s) should scale as
s  2 2 ( RPt  RV ) / 100 . This yields a value of s=-2.2x10-4 which is quite close to the fitted one,
s=−2.37x10-4. This clearly indicates that the lattice parameter of the alloy is primarily governed by the statistical
distribution of V atoms on the fcc lattice of Pt.
124
In principle, the measurement of the lattice parameter in such alloys is clearly a way to ascertain the content of
vanadium in the material with a very high precision.
Figure 2: Lattice parameters as a function of V content
Figure 1: X-ray patterns of Pt 1-xVx alloys
References
1. A Vegard, Z. Phys. 5 (1921) 17.
2. M F Trope, E J Garboczi, Phys. Rev. B 42 (1990) 8405.
125
2.5.7 Real-time Rutherford backscattering spectrometry (RBS) study of complex
formation of Pt-germanides
D Smeets1,2, J Demeulemeester1, C M Comrie3, W Knaepen4, C Detavernier4 and A Vantomme1
Instituut voor Kern-en Stralingsfysica and INPAC, KULeuven, B-3001 Leuven, Belgium
de Physique, Université de Montréal, Montréal, QC, Canada H3C 3J7
3 Department of Physics, University of Cape Town, Rondebosch 7700, South Africa
4 Vakgroep Vaste-stofwetenschappen, Universiteit Gent, B-9000 Gent, Belgium
1
2 Département
In future high-performance devices based on germanium-CMOS-technology, metal germanides will take an as
important role as silicides have done in silicon-CMOS-technology. Among the metal germanides, NiGe, PdGe,
and PtGe are the most promising candidates to contact the source, drain and gate areas of Ge-based transistors.
From a more fundamental point of view, the Pt-Ge system is particularly interesting because of the multiple Pt-Ge
phases that form consecutively in a solid state reaction and the marked difference in epitaxial quality of these
germanides on Ge(111), all phases grow epitaxially, and Ge(100), all phases grow in a polycrystalline way.
Because of the numerous advantages over the cook-and-look approach, real-time analysis techniques have
become the standard in thin film formation studies. Most often, real-time X-ray diffraction (XRD) is applied to
investigate the phase formation sequence and study the growth kinetics when a metal film reacts with the
substrate as the specimen temperature is increased during a ramped anneal. Epitaxial films however escape
detection in real-time XRD measurements. This technique however becomes unsuitable when the films grow
epitaxially on the selected substrates, because epitaxial films escape detection in real-time XRD measurements.
Moreover, XRD only contains indirect thickness information, whereas Rutherford backscattering spectrometry
(RBS) composes direct depth sensitive thickness information which is more reliable to study growth kinetics.
Additionally, RBS allows investigating the formation of epitaxial phases as well as polycrystalline films.
Samples for this investigation were prepared at the University of Ghent, Belgium, and the results were obtained at
the MRG. The investigation involved a real-time RBS study of the complex formation of platinum-germanides
during the solid state reaction. Real-time XRD measurements have shown the consecutive formation of Pt2Ge,
Pt3Ge2, PtGe, Pt2Ge3 and PtGe2 on Ge(100) during ramped annealing. From the stoichiometric information in the
real-time RBS data we can clearly observe that the Pt2Ge and Pt3Ge2 phases grow simultaneously and coexist
until the onset of PtGe formation. There is a small temperature window over which the PtGe phase is stable
before the Pt2Ge3 phase forms. All these phases grow in a layer-by-layer fashion induced by a diffusion controlled
process, whereas the growth of PtGe2 is columnar and instantaneous, as dramatically shown in the real-time RBS
data below, representing all the properties of a nucleation controlled reaction. Real-time RBS shows a similar
phase sequence on the Ge(111) substrate, for which no information can be obtained using real-time XRD due to
the epitaxial growth of all germanide phases on this substrate, but with markedly different growth rates. The
comparison of the growth rates on Ge(100) and Ge(111) allows us to investigate the mutual influence of the
epitaxial quality of thin films on their growth kinetics.
126
Figure 1: Contour plots from RBS spectra obtained during real-time RBS analysis of a Pt film on a Ge<100> substrate. The Pt signal
falls in the channel region 415 – 480 and that of Ge in channels 300 – 415. The diagonal shape of the Pt contour lines as they drop
from plateau to plateau are indicative of layer-by-layer growth during (i) Pt to Pt2Ge3/Pt3Ge2 formation, (ii) Pt2Ge3/Pt3Ge2 to PtGe and
(iii) PtGe to Pt2Ge3 formation (red to green). The more horizontal contours separating the green and the blue plateaus is indicative of
columnar growth during the conversion of Pt2Ge3 to PtGe2.
2.5.8 Real-time Rutherford backscattering spectrometry to determine the dominant
diffusing species during nickel germanide growth.
C M Comrie1, J Pondo2, D Brunco3, D Smeets4,5 and A Vantomme4
Department of Physics, University of Cape Town, Rondebosch 7700, South Africa
Department of Physics, University of Zambia, Lusaka 10101, Zambia
3 IMEC, B-3001 Leuven, Belgium
4 Instituut voor Kern- en Stralingsfysica and INPAC, K.U.Leuven, B-3001 Leuven, Belgium
5 Département de Physique, Université de Montréal, Montréal, QC, Canada H3C 3J7
1
2
It is generally believed that germanium, with its higher electron and hole mobility, will eventually become the
semiconductor of choice for high-performance devices. However, before germanium can be adopted a suitable
material for making electrical contact to the active areas of the transistor (i.e. the source, drain and gate) must be
identified. The use of metal-germanides, analogous to the metal-silicides used in silicon-based technology, is
proposed for this purpose. Of all the possible metal germanides, NiGe looks to be the most promising candidate.
A thorough understanding of all processes involved in germanide formation will be essential to the successful
implementation of nickel germanide in Ge-based transistors. Chief amongst the information required is the
identification of the dominant diffusion species during nickel germanide phase formation.
Rutherford backscattering spectrometry (RBS) has been proven to be one of the most valuable techniques to
study the diffusion of species during phase formation. Conventionally, in diffusion studies a thin layer of an inert
marker is deposited between the substrate and the overlying metal film. These specimens are then annealed,
one by one, for various durations or at different temperatures to induce differing amounts of phase formation.
127
Subsequently, the specimens are analyzed to unravel the diffusion process during the formation of the phase. It is
much more convenient to determine the specimen properties in real-time, i.e. during annealing. Not only does
this drastically decrease the workload, but it also eliminates the influence of small differences in the samples and
experiments. Furthermore it enables one to follow the diffusion process at all stages of phase formation, limiting
the risk of overlooking important steps in the diffusion process.
In this investigation a thin 4Å layer of tantalum has been used as an inert marker to determine the dominant
diffusing species during Ni5Ge3 and NiGe phase formation. To study diffusion during Ni5Ge3 formation the thin Ta
layer was interposed directly between the Ni film and the Ge<100> substrate, while for NiGe formation a thin film
amorphous Ge was also included above the Ta marker to enable the first phase to form before the marker was
involved in NiGe formation. RBS data acquired during ramped thermal anneals of the samples show that Ni is
the sole diffusing species during Ni5Ge3 formation. For second phase formation the real-time RBS data show that
both Ni and Ge diffuse during NiGe formation, but Ni is the dominant diffusing species during the growth of this
phase, contributing to about 85% of the overall growth. The major advantage of real-time RBS is that it enables
one to follow the diffusion process at all stages during growth. A detailed analysis of the real-time RBS data
shown in Figure 1 indicates that the Ni / Ge contribution does not remain constant throughout NiGe growth, with
the Ge contribution to NiGe growth being significantly larger during the initial stage (i.e. ~40%), and drops off to
~5% by the end.
Figure 1: Plot of NiGe formed above the marker during NiGe formation. If Ge is the sole diffusing species then all
the NiGe will be formed above the marker, wheras if Ni is the sole diffusing species during the conversion of
Ni5Ge3 to NiGe only 60% of the NiGe will be formed above the marker.
128
2.5.9 In situ, real-time RBS to study the redistribution of impurities during silicide
formation
J Demeulemeester1, D Smeets1,2, C M Comrie3, N P Barradas4 and A Vantomme1
Instituut voor Kern- en Stralingsfysica and INPAC, KULeuven, B-3001 Leuven, Belgium
de Physique, Université de Montréal, Montréal, QC, Canada H3C 3J7
3 Department of Physics, University of Cape Town, Rondebosch 7700, South Africa
4 Instituto Tecnológico e Nuclear, Estrada Nacional 10, Apartado 21, 2686-953 Sacavém, Portugal and Centro de
Física Nuclear da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1699 Lisboa Codex, Portugal
1
2 Département
Throughout the development of CMOS-technology, silicides have taken a prominent place. Whenever
technological demands on the silicide properties became more stringent, research efforts increased and most
often impurities came to the rescue because of the advantageous influence they have on the silicide growth
kinetics and the electrical and morphological properties of the material. For instance, Mo was added to TiSi 2 to
increase the C-54 TiSi2 nucleation density, Ni was added to CoSi2 to lower the nucleation temperature, and
nowadays transistors are manufactured with Ni-silicides containing Pt as an impurity. Pt is used here to increase
the thermal stability of NiSi. In order to understand how these impurities modify the silicide growth properties and
consequently the electrical and morphological properties of the silicides, it is indispensable to examine their
redistribution throughout the successive stages of silicidation.
Rutherford backscattering spectrometry (RBS) has been proven to be most useful to probe elemental diffusion in
a solid state reaction and is the ideal technique to study the distribution of impurities in a thin film. However,
monitoring the impurity redistribution ex situ and via a discrete set of quenched samples yields a large risk to
overlook important steps during silicidation. It is therefore desirable to probe the redistribution profile in situ and
during the annealing process by real-time RBS. Moreover, the direct thickness information on all the growing
phases obtained by RBS enables us to quantify the influence of impurities on the silicide growth kinetics from a
single real-time RBS measurement.
Real-time RBS has been used to investigate the redistribution of Pt during NiSi formation. Due to the high
Z-number of Pt, a high sensitivity to subtle but important changes in the impurity distribution is obtained, which
allows us to monitor their influence on the silicide growth and properties for marginal impurity concentrations
(down to 1 at.%). The contour plots of RBS spectra are shown in Figure 1. Analysing the continuous but drastic
fluctuations in the Pt concentration at the silicide/Si interface enabled us to explain the inhomogeneous Pt
distribution after complete NiSi formation and the influence of Pt on the NiSi texture causing the increase in
thermo dynamical stability.[1] For example, detailed analysis of the spectra obtained at 375C (Figure 2) shows
that although the Ni concentration in the Ni2Si is very low the concentration in the initial NiSi phase is much
higher. Real-time RBS thus provides valuable and useful information on thin film growth in these and other
ternary systems, and helps us to understand their phase formation sequence, stress evolution, morphological and
electrical properties.
129
Figure 1: Contour plots of RBS spectra obtained during a ramped thermal anneal (2C / min) of a
NiPt alloy (containing 3% Pt) deposited on a Si(100) substrate.
Figure 2: RBS spectra acquired at 375C (indicated by solid line in Figure 1), together with the
RUMP simulation. At this temperature the NiSi seed layer (indicated with an arrow) is formed. The
inset represents the sample structure obtained from the simulation.
References
1. J Demeulemeester, D Smeets, C Van Bockstael, C Detavernier, C M Comrie, N P Barradas, A Vieira, and
A Vantomme, Appl. Phys. Lett. 93 (2008) 261912.
130
2.5.10 Magnetic Force Microscopy (MFM) imaging at the SPM Laboratory
M M Nkosi1 and R Nemutudi1
1iThemba
Magnetic force microscopy (MFM), first demonstrated by Martin et al. [1], involves measurements of the spatial
variation of the magnetic force of interaction between a magnetic tip and a sample by using non-contact force
microscopy. In MFM the tip is coated with magnetic material to sense a stray magnetic field from the surface.
Magnetic interactions are weak but long-range compared to van der Waals forces, so that the magnetic
interaction is dominant above tens of nanometers in tip-sample height. Magnetic force microscopy is done in a
two-pass method where the surface topography is measured in the first pass in tapping mode. In the second pass
the tip is lifted to a user defined height from the sample surface and the same line scan is carried out, while
maintaining a constant height separation.
Within a distance of 10 to 500 nm of tip-sample separation [1], magnetic interaction of the tip with the stray field
emanating from the sample becomes noticeable and the interaction strength can be determined by various
methods such as phase shift, frequency modulation or amplitude change. These detection methods, that usually
probe the long range magnetic dipole interaction, are sensitive to force gradients rather than magnetic dipole
forces. The magnetic interaction energy between the tip and the sample is
𝑈=−
𝑡𝑖𝑝
Mtip(r)∙B(r)𝑑𝑟
where Mtip(r) is magnetic moment of the tip, and B(r) is the stray field from the sample.
MFM has now become a well-established technique that is used for non-destructive, fast mapping of magnetic
features on a sample. MFM has also found many industrial applications since magnetic and magneto-optic media
are of interest. The most common application is mapping a magnetic topography (of the sample), which requires
that the sample stray field be not affected by the probe magnetization and vice versa.
In this work we have employed etched antimony (n) doped silicon tips of the MESP type supplied by Veeco.
These are standard probes for MFM. The magnetic coating consists of between 10 and 250 nm of CoCr alloy (the
exact thickness and composition of the coatings are undisclosed). The cantilever is longer than that for the
standard tapping mode probe, with a length L = 200 – 250 µm instead of 115 – 135 µm. As a result the
resonance frequency is considerably lower (f0 = 60 - 100 kHz instead of 303 – 344 kHz). In order to ensure a
predominant orientation of the magnetic field vector along the major probe axis, the thin film probe was
magnetized prior to taking measurements.
Figure 1 shows an MFM image that was collected with our MFM microscope. The sample was a piece of
magnetic recording tape; a standard sample that is used to check whether the microscope is correctly tuned to
image magnetic materials. It is clear that no correlation exists between the topography data shown on the left and
131
the phase shift data on the right. Even though the signals were recorded in continuously alternating scan lines,
the separation of both contributions is successful.
Figure 1: Topographic image (left) and magnetic force gradient image (phase signal)
(right) of magnetic recording tape, data scales 100 nm and 4° respectively, lift height was 100 nm.
Reference
1. Y Martin and H K Wickramasinghe, Applied Physics Letters 50 (1987) 1455.
132
2.5.11 Magnetic force microscopy (MFM) on nickel thin films
M M Nkosi1 and R Nemutudi1
1iThemba
LABS, P O Box 722, Somerset West, 7129
In this investigation we explored magnetic force microscopy (MFM) as a technique for direct imaging of the stray
field pattern arising from nickel thin films supported on a Si substrate. Nickel films, 250 nm thick, were deposited
using a high vacuum electron beam evaporator. Imaging was performed in air with the Nano-Man V AFM from
Digital Instruments housed at the Materials Research Department. The MFM tip was of the commercially
available MESP type coated with between 10 and 250 nm ferromagnetic CoCr alloy.
Figure 1: Height and phase images of Ni film deposited on Si substrate acquired at the same time, with a probe
lift-height of 40nm. The phase contrast range is 4°. The MFM image is not directly related to the topography.
Figure 1 shows the topographic and the corresponding MFM images of a 5 µm x 5 µm area of Si substrate with
deposited Ni film. In the MFM image, the dark contrast corresponds to an attractive interaction and, conversely,
the bright contrast corresponds to repulsive interaction given that the magnitude of the force on the tip decays
with increasing distance from the surface [1, 2]. The scan height was 40 nm in lift mode. A series of
measurements were performed where the lift scan height was increased in steps of 10 nm. A lift height of 30 nm
was the minimum required for stable scanning. Above 140 nm there is a fast decrease in the MFM signal. The
dependence on lift height followed the same pattern on other Ni samples as well. Moreover, van der Waals forces
only become significant at tip-sample distance below 30 nm.
References
1. S A Koch, R H te Velde, G Palasantas, J Th M de Hosson, Applied Surface Science 226 (2004) 185.
2. R D Gomez, A O Pak, A J Anderson, E R Burke, A J Leyendecker, and I D Mayergoyz, J. Appl. Phys. 83
(1998) 6226.
133
2.5.12 Micro-PIXE mapping of elemental distribution in roots of a Mediterranean-type
sclerophyll, Agathosma betulina (Berg.) Pillans, colonized by Cryptococcus
laurentii
K J Cloete1, W J Przybylowicz2, J Mesjasz-Przybylowicz2, A D Barnabas2, A J Valentine3, A Botha1
Department of Microbiology, Faculty of Science, University of Stellenbosch, Private Bag X1, MATIELAND,
7602, Western Cape, South Africa
2 Materials Research Group, iThemba LABS, P O Box 722, Somerset West 7129, South Africa
3 Plant Physiology Group, South African Herbal Science and Medicine Institute, Faculty of Science, University of
the Western Cape, Private Bag X17, Bellville, 7535, Western Cape, South Africa
1
Buchu (Agathosma betulina, Rutaceae) is a fynbos plant of enormous medicinal and ethnobotanical value to
South Africa [1]. Plantations of A. betulina are obtained by the transplantation of five-month old nursery seedlings
to its natural habitat, which is characterized by leached soils with a low nutrient status. Seedling survival is
however less than 10% [2]. Since it is known that yeast have a beneficial effect on plant performance [3], it was
postulated that inoculation of nursery seedlings with yeast indigenous to the plant‟s rhizosphere, would increase
plant nutrition. This study therefore focused on quantitative elemental distribution within the roots of A. betulina,
colonized by Cryptococcus laurentii as well as within controls grown under nutrient-poor conditions. After
harvesting, root material was immediately cryofixed in liquid propane using a Leica EM CFC Cryoworkstation and
freeze-dried in a Leica EM CFD Cryosorption Freeze Dryer. Thin cross sections of the material were
subsequently mounted between two layers of formvar, one of which was carbon-coated. The elemental
distribution in inoculated and control A. betulina plants was characterized using micro-PIXE spectrometry in
combination with Rutherford backscattering spectrometry. To aid in the interpretation of heterogeneous elemental
distribution patterns, apoplastic barriers (Casparian bands) in root tissues were identified using fluorescence
microscopy.
In addition, root cross-sections were examined for endophytic C. laurentii using light and
transmission electron microscopy (TEM). The average concentration of P, Fe and Mn were significantly higher
(P < 0.05) in roots of yeast-inoculated plants, compared to control plants. Casparian bands were observed in the
exodermal and endodermal cells (Figure 1) of both treatments and the presence of these bands was correlated
with elemental enrichment in the epi/exodermal-outer cortical tissues (Figure 2). Light and TEM micrographs
revealed that the yeast was not a root endophyte. This is the first report describing the role of a soil yeast as a
plant nutrient-scavenging microsymbiont.
References
1. K J Cloete, A J Valentine, L M Blomerus, A Botha and M A Pèrez-Fernández, Web Ecol. 77 (2007) 77-86.
2. M De Ponte Machado. 2003. Is buchu (Agathosma betulina) harvesting sustainable? Effects of current
harvesting practices on biomass, reproduction and mortality. Master of Science in Conservation Biology
Dissertation, University of Cape Town, S.A.
3. K A El-Tarabily and K Sivasithamparam, Mycoscience 47 (2006) 25-35.
134
Figure 1: (a) Fluorescence micrograph of berberine hemisulphate-stained root cross section of Agathosma betulina. White arrows
indicate fluorescing Casparian bands in the endodermis. Scale bar = 40 µm. (b) Casparian bands in the anticlinal walls of
exodermal cells (large white arrow), and Casparian bands in the transverse walls of exodermal cells (smaller white arrow). The root
epidermal layer was detached during sectioning and/or staining procedures. Scale bar = 20 µm.
Figure 2: Quantitative elemental PIXE maps of phosphorus and iron distribution in Agathosma betulina root cross sections colonized by
Cryptococcus laurentii showing elemental enrichment in the epi/exodermal-outer cortical root regions. Concentrations are presented in wt%.
135
2.5.13 Structural organization and elemental distribution in root nodules of psoralea
pinnata (L) by TEM and Micro-PIXE
S A Kanu1, M Jaffer2, R Bucher3, A D Barnabas3, J Mesjasz-Przybylowicz3, W J Przybylowicz3 and F D Dakora1
1 Tshwane
University of Technology, Faculty of Science, Pretoria 0001, South Africa
of Cape Town, Electron Microscopy Unit, Rondebosch 7700, South Africa
3 iThemba LABS, Materials Research Department, P O Box 722, Somerset West 7129, South Africa
2 University
Psoralea pinnata (L) is a legume belonging to the tribe Psoraleae and is found only in the Cape Floristic Region
of South Africa known as fynbos. The plant occurs naturally in both wetland and upland conditions, suggesting
that the internal organization of nodules must be different under the two contrasting environments. Because N 2
fixation by rhizobium bacteroids depends on adequate supply of O2 for ATP production, Psoralea nodules
developed in wetlands are more likely to show adaptation to low O2 supply. The aim of this study was: i) to assess
if the differences in the pO2 in the two contrasting natural habitats of P. pinnata altered nodule structure and
internal organization, and ii) to quantify elemental distribution in different nodule components (i.e. outer cortex,
middle cortex, inner cortex and bacteria-infected medulla).
The structural organisation and elemental distribution in P. pinnata nodules were determined using TEM and
Micro-PIXE respectively. Nodules used in this study were developed in their natural habitats within the fynbos.
Elemental analyses were performed using the Nuclear Microprobe at the Materials Research Department,
iThemba LABS, South Africa. TEM and light micrographs revealed differences in internal organization and
distribution of cell types between wetland and upland nodules. Analysis of morphometric measurements showed
a highly reduced medulla in wetland nodules and an enlarged cortex. This was in sharp contrast to the increased
size of the medulla and the reduced cortex in nodules from well drained soils. The shape and size of individual
cells and extracellular airspaces also differed across tissue components in the two nodule types.
The number of bacteriods per micrograph of infected cells in the medulla was lower in wetland nodules (data not
shown). In addition, quantitative elemental maps showed differences in concentrations and distributions of major
and trace elements in the two types of nodules (Figure 1). A two-way ANOVA analysis with the Duncan test
further revealed significant differences (p≤0.05) in the average concentrations of elements (µg g -1 dry weight) in
the same nodule component when compared between the two types of nodules. For example, there were
significantly high concentrations of K (µg g-1 DW) in all components of wetland nodules compared to those of
upland nodules. Higher concentrations of P, Mn, Fe and Mo were detected in the medulla of wetland nodules
compared to the medulla of the upland nodules.
The presence of calcium oxalate crystals in the outer cortex of both types of nodules was confirmed by
histochemical tests using the Yasue [1] method (see Figure 2). By X-ray diffraction analysis, two kinds of calcium
oxalate crystals, whewelite and whadelite, were identified in freeze-dried Psoralea root nodule powder (data not
shown). Taken together, these results provide further evidence that oxygen relations in root nodules in legumes
involve the internal structural organization of the nodule as have been reported by other authors [2, 3].
136
Differences in concentrations of elements and distribution in the two types of root nodule studied are likely due to
environmental conditions.
References
1. T Yasue, Acta Histochem. Cytochem. 2(3) (1969) 83-95.
2. F D Dakora and C A Atkins, Planta 182 (1990) 572-582.
3. J Tjepkema and C S Yocum, Planta 119 (1974) 351-360.
Figure 1: Quantitative elemental maps showing distributions of K, Fe, and P in cross-sections of Psoralea pinnata root nodules
growing in both dry-upland (top) and wetland (bottom) conditions in the Cape Floristic Region in South Africa.
Figure 2: Light microscope images ((A) 40 x and (B) 20 x magnifications) of P. pinnata root nodule sections. Calcium oxalate crystals
are present in the outermost parts of the outer cortex next to the middle cell boundary. Inner cortex (IC), medulla (M), middle cortex
(MC), vascular bundles (VB) and outer cortex (OC) are shown.
137
2.5.14 The growth of Fe1-xCoxSi thin films by pulsed laser deposition for Spintronics
applications
N I Manyala1, B Ngom2, R Bucher2, M Maaza2, A C Beye3 and J F DiTusa4
Department of Physics, Institute of Applied Materials, University of Pretoria, South Africa
iThemba LABS, P O Box 722, Somerset West 7129, South Africa
3 Sciences et Techniques, Universite Cheikh Anta Diop de Dakak, B. P. 25114 Dakar Fann Dakar, Senegal
4 Department fo Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA
1
2
The films of Fe1-xCoxSi were synthesized using pulsed laser deposition (PLD) at the National Laser Center in
Pretoria. The experiments carried out at iThemba LABS focussed on the characterization of structural, surface
morphology and film thickness and composition using X-ray diffraction (XRD), Atomic Force Microscopy (AFM)
and Rutherford back scattering (RBS) respectively. The objective of this project was to grow thin films of
Fe1-xCoxSi with structures similar to those of their bulk counterparts. Once this is achieved, then further
characterization and measurements of interest, such as magnetic and transport measurements, would be carried
out.
4.5
8000
Fe1-xCoxSi Films
7000
111
4.485
6000
5000
4000
110
(Si 111)
200 210
0
221
x = 0.3
3000
x = 0.2
2000
x = 0.15
0.1
0.2
x
222
321
0.3
400
4.47
x = 0.1
1000
x = 0.0
0
30
45
60
75
90
2 (degree)
Figure 1: X-ray diffraction from Fe1-xCoxSi thin films grown via laser ablation with 900 s deposition time with x values denoted in the
figure. Inset: Lattice constant versus Co concentration for films (bullets) and bulk (filled squares). Solid lines through data are a
linear fit confirming Vegard‟s law.
Figure 1 shows the 2 scan of our films and we have identified all discernable peaks in the XRD as belonging to
either the B20 structure of the films or the diamond structure of the Si substrate. No evidence for the secondary
impurity phases has been found in any of the scans indicating that the films are likely single phase. The lattice
constant, a, of the films, presented along with bulk values as a function of x in the inset [1,2], are larger than in
bulk samples by ~0.3% at small x. The lattice 17% mismatch between the Si (111) substrate and the FeSi films
cause significant strain near the film-substrate interface. However, as our films are between 35 and 500 nm thick,
138
changes in a due to interfacial strain are not expected since it is typically relieved via crystalline defects within a
few nm of the interface. Stoichiometric fluctuations have been ruled out as the cause of the expanded lattice by
our RBS and EDX measurements. These results together with magnetic characterization of the films have been
published [3,4].
References
1. N Manyala, Y Sidis, J F Ditusa, G Aeppli, D P Young and Z Fisk, Nature Materials 3 (2004) 255.
2. N Manyala, Y Sidis, J F Ditusa, G Aeppli, D P Young and Z Fisk, Nature 404 (2000) 581.
3. N Manyala, B D Ngom, A C Beye, R Bucher, M Maaza, A Strydom, A Forbes, A T Johnson, Jr and
J F DiTusa, Applied Physics Letters (2009) (in press).
4. N Manyala, B D Ngom, J B Kana Kana, R Bucher, M Maaza and J F DiTuSa, AIP Conf. Proc. 1047 (2008)
127.
2.5.15 On-surface diffusion of gold and copper atoms in Cu/Au/Si annealed systems
C Benazzouz1, H Hammoudi1, N Benouattas2, C A Pineda-Vargas3
Centre de Recherche Nucleaire d_Alger, CRNA, 2 Bd Frantz Fanon, 16000 Algiers, Algeria
Faculte´ des Sciences, Département de Physique, Universite´ Ferhat-Abbas, Sétif 19000, Algeria
3 Materials Research Department, iThemba LABS, P O Box 722, Somerset West, 7129, South Africa
1
2
From a technological standpoint, the knowledge of interdiffusion between a metal bilayer and silicon is of
increasing interest in very large scale integration (VLSI) technology [1]. The Cu/(metal or silicide)/Si systems are
very attractive mainly because of their potential use for shallow silicide contact and diffusion barriers [2].
Unfortunately, even at room temperature, copper is very mobile in silicon leading to the creation of trap levels in
the silicon matrix that are deleterious to the device performance [3]. For this reason, it is of interest to understand
the mechanisms that govern the interdiffusion of copper and silicon through barrier layers. Gold can form an
appropriate barrier because it may penetrate through the silicon without reacting with it and presents a low
electrical resistivity of 2.35  cm-1 [4] for ohmic contacts. We report on the results of the behaviour of silicon and
copper diffusion in the presence of gold atoms.
Copper and gold thin films were thermally evaporated on (111) Si wafers. In order to promote diffusion, the
resulting samples were annealed under vacuum at 200°C or 400°C for 30 minutes in a quartz crucible.
Qualitative and quantitative analyses of samples have been carried out by means of different techniques such as:
Rutherford backscattering spectrometry (RBS) (2 MeV,
4He+);
Nuclear Microscopy (NMP) (probe
size:~2.4x3.0 m2, mapping size: 130x130 m2 and map size: 52x52 Pixels), Scanning Electron Microscopy
(SEM), Atomic Force Microscopy (AFM) and X-ray Diffraction (XRD) (Cu K). The composition and thickness of
the formed phases was determined by RBS and the spacial distribution of elements over the surface of the
multilayer system was obtained by Dynamic Analysis using the software package Geo-PIXE II [5]. The XRD in the
–2 mode was used to identify the formed compounds. The morphology of samples‟ surfaces was examined by
SEM and the samples‟ surface roughness was obtained by AFM analysis.
139
Typical X-ray diffraction patterns corresponding to Cu/Au/Si(111) as deposited were obtained. In particular
Cu (111) and Au (111) peaks were present without any trace of the other reflection lines of the copper and gold
powders. This preferential orientation suggested an epitaxial growth of evaporated copper and gold grains when
Au and Cu layers are used as seed layers on Si (111) respectively. It was found by RBS that before annealing
the system exhibits Cu/Au and Au/Si abrupt interfaces without any apparent interdiffusion or reaction between the
different elements. After annealing at 200°C, the SEM micrographs of the Cu/Au/Si(111) structure presented a
rough metal surface. Whereas, in the correspondent backscattering spectrum, Au and Cu signals overlap for such
a structure, because of the thickness increase of the new compound formed at the interface. On the other hand,
the backscattering yields of Au and Cu signals decreased because of the strong interdiffusion between the
different elements. For the Cu/Au/ Si structure, the two peaks of Cu and Au have a flat profile and correspond to
a uniform Cu–Au mixing layer. By simulation it was found that about 55 at.% Cu and 20 at.% Au, interdiffused
through 25% silicon to form a silicide thickness of about 2480 Å. These compositions are well corroborated by
global X-ray microanalysis where similar percentages were found.
Since the atoms of gold cannot react with those of the silicon, the formation of gold silicide is excluded. The
distribution of Au in the hexagonal motive (about 70-80%, see Figure 1) may indicate that the phase is either
Cu3Si or Cu4Si. After annealing at 200°C, both silicon and gold have moved to the surface leading to a growth of
polycrystalline Cu3Si and Cu4Si copper silicides. The RBS analysis showed that the copper phases are mixed
within the growth layer with a uniform composition in depth. The gold deposited layer dissolved itself completely
during the reaction between Cu and Si showing the high solid solubility of gold atoms in copper silicide
compounds.
Figure 1: Elemental maps of gold, copper and silicon obtained by nuclear microscopy. Beam probe ~ 3x4 mm2 ; mean current 100 pA ; scan
size 56x56 pixels; dwell time 12 ms. Bar scale in microns. The gold atoms in the barrier diffuse through hexagonal motive on the copper
silicides formed after annealing at 200°C for 30 minutes.
References
1. M A Nicolet, S S Lau, VLSI Electronics Microstructure Science, in: J. Einspruch, G.B. Larrabee (Eds.),
Materials and Process Characterization, 6 (1983) Academic Press.
1. S-Q Wang, Mater. Res. Soc. Bull. XIX (8) (1994) 30.
2. S P Murarka, Silicides for VLSI Applications, Academic Press, London, 1983.
3. C Benazzouz, N Benouattas, A Bouabellou, Nucl. Instr. and Meth. B 213 (2004) 519.
4. C G Ryan, D R Cousens, 2002. Geo-PIXE II Quantitative PIXE trace element analysis and imaging. CSIRO
Exploration and Mining, North Ryde, NSW 2113, Australia.
140
2.5.16 Structural and electric characterization of Ni and Ni/Ti contacts on n-type 4H-SiC
M Siad1, C A Pineda-Vargas2, M Nkosi2, A C Chami3
Centre de Recherche Nucleaire d‟Alger, 02 Bd Frantz Fanon, Alger, Algeria
Materials Research Group, iThemba LABS, P O Box 722, Somerset West, 7129, South Africa
3 USTHB, Faculty of Physics, BP 32, El Alia, Bab Ezzouar, Alger, Algeria
1
2
Silicon carbide (SiC) is a semiconductor material with excellent physical and electrical properties. It presents a
larger band gap (3.3 eV), a higher breakdown field (2 x106 V/cm) and a higher thermal conductivity (4.9 W/cm K),
compared to widely used silicon [1]. These properties make SiC very attractive for high temperature, high-power
and high-frequency electronic devices. Metallization is one of the most important steps in the fabrication of
electronic devices. In the contact metal/SiC, the difficulty lies in the control of the interface properties and the
height of the Schottky barrier [2]. These properties of the metal/SiC interface include uniformity and thickness of
the interfacial region, and most importantly, the Schottky barrier height (SBH). For reliable SiC device operation,
stable ohmic contacts with low specific contact resistance are necessary. Several metals are currently being
investigated for the preparation of electrical contacts. Among them, Nickel and Titanium have attracted much
attention as an ohmic contact for n- type SiC, due to their low contact resistivity. In this work, we report on the
structural characterisation of Ni and Ni/Ti bilayer contacts on n- type 4H-SiC. We were mostly interested in the
role, redistribution and chemical state of C after annealing, since these appear to be the most controversial
aspects in studying the Ni/SiC and the Ni/Ti/SiC type contacts [3,4].
The samples consisted of an n- type 4H–SiC epitaxial layer, 10 m thick, grown on an n- type substrate of 4H–SiC
(thickness 360 m, 0.017 cm). The net doping concentration in the epitaxial layer is 2.05 x 1015 cm-3. An
n+ type buffer layer, 0.5 m thick with a doping concentration of 1x1018 cm-3, lies between the epitaxial layer and
the substrate. The samples were chemically cleaned and then Ni (100 nm) and Ni(100 nm)/Ti(20 nm) films were
evaporated onto the whole backside of the wafer (C face), with a deposition rate of 3 Å/s, and annealed at 950°C
for 10 minutes in vacuum (10-8 mbar) to form a large area low-resistance ohmic contact.
Rutherford Backscattering Spectrometry (RBS) and Elastic Backscattering Spectrometry (EBS) with 2.0 and
3.0 MeV 2He+ beam particles respectively were used to characterize the contacts. We exploited the enhanced
scattering cross section for  particles at 3.2 MeV and scattering angle =165° to improve the sensitivity of the
reaction 12C(, )12C. The excitations of strong resonances at 3.75 MeV and around or above 4 MeV are
avoided. Surface morphology of the samples was examined by AFM (Atomic Force Microscopy). The asdeposited contact surface appeared homogeneous and smooth with RMS surface roughness of 12-13.6 nm and
small depressions with vertical dimensions of 107-112 nm. The value of surface roughness remains almost
constant after heat treatment. Thus the surface morphology of the contact does not change and should maintain
excellent wire-contact mechanical durability during high power and high temperature device operation [5].
XRD analyses were carried out in order to identify the formed phases and their crystallographic orientations. For
the as-deposited samples, the diffraction peaks corresponding to Ni (111) and Ni (200) were observed. After
annealing, these peaks disappear, indicating that the deposited film completely reacted after thermal treatment
141
where the Ni2Si phase is formed. The microstructure of Ni based metallization on n type 4H-SiC, after thermal
annealing at 950°C showed (by XRD analysis) a profile which correspond only to a Ni2Si phase. This result is in
agreement with published data. Results obtained by RBS clearly showed that carbon is uniformly distributed
through the silicide and accumulated at the top surface (see Figure 1), after thermal treatment.
Figure 1: Experimental RBS spectra of the samples of Ni/ SiC as deposited and
after annealing at 950°C.
References
1.
2.
3.
4.
5.
P J Sellin et al., Nucl. Instr. and. Meth. A 557 (2006) 479-489.
B Pécz et al., Applied Surface Science 184 (2001) 287-294.
F La Via et al., Microelectronic Engineering, 70 (2003) 519-523.
Y Gao et al., Solid-State Electronics 44 (2000) 1875-1878.
M W Cole et al., J. Appl. Phys. 88(5), (2000) 2652.
2.5.17 Evaluation of stopping power on thin polymer foils with heavy ions ERDA –TOF-E
spectrometer at the K1-line of the iThemba LABS Cyclotron
M Msimanga1, H Ammi2, C A Pineda Vargas1,
1 Material
2 Centre
Research Department, iThemba LABS, P O Box 722, Somerset West, 7129, South Africa
de Recherche Nucléaire d‟Alger, 02 Bd Frantz Fanon Alger, Algeria
An experimental method based on heavy ion elastic recoil detection analysis using a Time of Flight-Energy
spectrometer (TOF-E) [1], has been used to measure energy loss of charged particles in thin polymer foils.
Measurements were carried out at the Cyclotron facility at iThemba LABS using an ECR source to inject the
heavy ions into the SPC2 injector. Krypton ion beams of 27.5 MeV incident on different targets (Si, MgO, AlO,
LiF, C and BO) produced recoils which scattered into the Time of Flight – Energy spectrometer. The stopping
powers of
28Si, 27Al, 24Mg, 19F, 16O, 12C, 9Be
and 7Li ions in Mylar and Formvar in the energy range
100-760 keV/amu were determined. The energy loss of the recoil atoms was measured using the TOF
spectrometer and the Si surface barrier detector (located after the second MCP time detector), with and without
foils (Figure 1) placed in front of the surface barrier detector.
142
Figure 1: 2D Time of Flight (ToF) spectrum obtained for the silicon ion with and without Mylar
Good mass resolution was obtained for different types of recoil atoms (28Si, 27Al, 24Mg, 19F, 16O, 12C, 9Be and 7Li).
This observation allowed us to measure energy loss for thin polymeric foils and to compare our result with those
calculated by the popular code SRIM 2008.
The mean deviation between the experimental stopping powers and those calculated by SRIM 2008 code were
3,52% for Silicon, 6,06% for Aluminium, 2,89% for carbon and 10,15% for Lithium ions, respectively. Preliminary
results for measured stopping power data for 28Si, in Mylar in the energy range 140 – 760 keV/amu are given in
Table 1 as an example.
 S cal  S exp

 S cal
Mean energy
(keV/amu)
28Si
Obtained stopping
power, Sexp.
(keV/g.cm2)
SRIM2008 stopping
power, Scal.
(keV/g.cm2)
146,458
14,373
13.79
%
−4,2
166,742
15,278
14.72
−3,8
184,006
15,899
15.43
−3,1
217,935
18,022
16.63
−8,3
245,633
18,266
17.46
−4,6
273,778
19,459
18.17
−7,1
299,102
18,766
18.74
−0,14
322,676
19,035
19.20
0,86
358,825
19,144
19.80
3,3
387,528
19,678
20.19
2,5
407,635
20,244
20.43
0,91



Table 1: Stopping power measured for 28Si on Mylar at different energies.
Good agreement of the measured stopping power values for 28Si, in Mylar, was obtained by theory using the
software SRIM 2008.
References
1. M Msimanga, Doctoral Thesis, University of Cape Town (in progress).
143
2.5.18 Magnetic Ordering in Diamond Induced by Proton Irradiation
E Sideras-Haddad1,3, C A Pineda-Vargas2, Th Makgato1, S Shrivastava1, M Madhuku3, K Sekonya3, A Strydom4
Department of Physics, University of the Witwatersrand, Private Bag, WITS, South Africa
MRD, iThemba LABS, P O Box 722, Somerset West, 7129, South Africa
3 iThemba LABS Gauteng, Private Bag 11, WITS, 2050, South Afric
4 Physics Department, University of Johannesburg, P O Box 524, Auckland Park 2006, South Africa
1
2
Recently, magnetic ordering in polymerized fullerenes and graphite was reported by the Leipzig group in
Germany [1]. This was also confirmed by the Stanford and Berkeley groups last year [2] using the Lawrence
Berkeley Laboratory's Advanced Light Source (ALS) and showed that pure samples of carbon can be made
permanently magnetic at room temperature. The effect is induced only by proton irradiation and is therefore
related to the hydrogen ions at specific lattice sites. Much research has been done on the magnetic properties of
carbon allotropic systems, as light nonmetallic magnets with a Curie point well above room temperature appear to
be very promising for many practical applications.
We have started similar research using the proton microprobe facility at iThemba LABS with subsequent
Magnetic Force Microscopy at the Wits AFM/STM facility. Preliminary magnetic force microscopy has shown
clear magnetic ordering of the proton irradiated micro-patterns while no magnetism was induced by alpha particle
irradiation. Figure 1 shows atomic force microscopy topological images of the proton irradiated area (left) together
with magnetic force microscopy images of the same area illustrating a clear observation of magnetic ordering
after irradiation (right). Further measurements are now undertaken using the newly established SQUID facility.
Theoretical modelling using density functional theory is also being undertaken.
Figure 1: Topological images mapped by AFM (left) showing the
topology of the proton microbeam scanned area. Magnetic Force
Microscopy (MFM) of the same area exhibits magnetic ordering.
144
The research programme will focus on identifying the causes of the effect, especially with emphasis on hydrogen
lattice residence sites in diamond and hydrogen diffusion. Of particular interest is the induced magnetism in
p-type semiconducting diamond in terms of spintronics applications and devices.
References
1. P Esquinazi et al., Phys. Rev. Lett. 91 (2003) 227201.
2. H Ohldag et al., Phys. Rev. Lett. 98 (2007) 187204.
2.5.19 Proton irradiation induced structural effects in C60 nano-rods
C B Mtshali1,2, J B Kana Kana1, P Sechogela1, R Bucher1, M Lekgoathi3, O M Ndwandwe2, M Maaza1
1Nanoscience
& Nanotechnology Laboratories, MRD, iThemba LABS, P O Box 722, Somerset West, 7129, South
Africa
2Department Physics and Engineering, University of Zululand, Private Bag X1001, KwaDlangezwa 3886, South
Africa
3Department of Chemistry, Tshwane University of Technology, Private Bag X680, Pretoria 0001, South Africa
Studies on C60 have progressed rapidly in wide areas of science and nanotechnology because of its interesting
properties [1-3]. Bulky C60 is an insulator having an optical absorption edge of about 1.6 eV [4]. Many researchers
have explored the possibility of altering the physical properties of C60 by doping with alkali metals which induce
both semiconducting and superconducting changes [5]. More specifically, the research literature reported by
Makarova et al. and Wood et al. showed the occurrence of ferromagnetic ordering in two dimensionally
polymerized highly oriented rhombohedral C60 (Rh-C60) phases which can be explained in terms of topological
defects. Some theoretical studies have predicted a ferromagnetic phase of mixed sp2 and sp3 pure carbon. This
can be made possible by chemical doping or by ion implantation [6-8]. This latter i.e. beam irradiation, changes
spatial arrangement of atoms in the solid material [9]. These changes in the spatial arrangement of carbon atoms
modify the electronic properties of carbon phases, which may be semiconductors, metals, or insulators and this
can be achieved with beam irradiation [10-14]. Structural effects in C60 films by Arsenic ion implantation were
investigated by Narayanan et al. [15]. Mathew et al. [16] reported that polycrystalline fullerene thin films on
hydrogen passivated Si (111) substrates irradiated by 2 MeV protons display ferromagnetic-like behaviour at 5 K
while at 300 K, both pristine and irradiated films show a pure diamagnetic behaviour. Likewise, magnetization
data in the temperature range of 2 -300 K, in 1 Tesla field, for the irradiated films show much stronger
temperature dependence compared to the pristine film. This latter behaviour was predicted by Yazyev et al. [17]
who studied the development stages of radiation damage in graphite and carbon nanostructures using first
principles molecular dynamics. Boukhvalov et al. showed that such a ferromagnetism induced phenomenon in
fullerenes is likely to have been induced by defects [18]. This latter statement corroborates with the findings of
Kumar et al. on the ferromagnetism induced by heavy-ion irradiation in fullerene films [19]. Besides all these
previous observations of ferromagnetism phenomenon in various carbon-fullerene based systems, one should
single out the recent experimental observations reported by Esquinazi et al. The reproducibility of the induced
magnetic ordering by proton irradiation in graphite [20] and its temperature evolution via Electron Spin
Resonance measurements demonstrate clearly the uniqueness of the proton irradiation.
145
In this study, we systematically study the structural changes induced by high-energy (MeV) proton irradiation in
C60 nano-rods films using Raman and X-ray diffraction as qualitative characterization tools to further conduct the
magnetic studies. A significant change in both vibration modes and crystallographic structure after irradiation was
observed.
C60 nano-rods were grown on Si(111) substrates by using a molecular recognition-self assembly methodology via
the so called Miyazawa liquid-liquid interfacial polymerization. The obtained nano-rods of C60 as shown in Figure
1 were subjected to protons irradiation. High energy (2 MeV) proton irradiation was carried out at room
temperature at various doses in the range of ~1.79 x 1016 to ~8.96 x 1016 ions/cm2. The beam current was
maintained at about ~50 nA while the beam spot size was fixed at 2 mm in diameter. The surface morphology of
the films was determined by Scanning Electron Microscopy (SEM). X-ray diffraction (XRD) of these C60 nano-rods
were recorded using a Bruker D8 advance X-ray diffractometer on the samples using CuK radiation of 1.54 Å in
the angular range of 7 to 35°. Raman spectra were performed at room temperature using a NdYAG laser
(=1064 nm).
Figure 1: Scanning electron Microscopy of nanorods
and precipitate of C60 on a Si (111) substrate.
Figure 2: Raman spectra of the irradiated C60
nanorod samples.
Figure 1 shows a scanning electron microscopy image of synthesized the C 60 nano-rods on Si(111) substrate
grown at room temperature for two days. It is clearly seen that the films are composed of a large amount of rods
having different nano-scaled diameters and micron-scale lengths. The diameter of most nano-rods ranges from
100 nm to 900 nm whereas their length is several hundreds of micrometers. The majority of the C60 nano-rods
have a diameter below 400 nm and finer C60 nano-rods with diameter less than 200 nm were also observed.
However, precipitates of pristine C60 are also observed.
Room temperature Raman spectroscopy measurements revealed that the Raman spectra of the pure C60
precursor powder (99,9% purity) and the synthesized C60 nano-rods for comparison were quasi-identical. The
films of C60 nano-rods exhibit all corresponding active Raman peaks as the standard C60 powder. This confirmed
the successful growth of pure C60 nano-rods without any features of chemical contamination.
146
Figure 2 shows the dose dependence of the Raman spectra of the various C60 nano-rod films on Si (111)
irradiated with 2 MeV H+ ions. It can be seen that the C60 molecule lines around 487 cm-1 and 1464 cm-1 i.e. the
Ag(1) and Ag(2) respectively, known as „pentagon pinch‟ modes and Hg(1) modes, develop more prominent
intensity with the increase of the H+ dose. More specifically, at the low dose of 1.79 x 1016 ions/cm2, the broad
peak around 1340 cm-1 can be attributed to the disordered peak of graphite, known as the graphite D peak. In
addition, the peak around 1581 cm-1 corresponds to the well-known G peak signature of graphite.
The
broadening of this specific Raman peak implies the deviation from the bulk crystalline graphite. The G and
D peaks appearing at low doses of 1.79x1016 ions/cm2, have a tendency to change to Hg(7) and Hg(8) Raman
active peaks as the dose increases to 8.96x1016 ions/cm2 respectively. This trend indicates the recovery of the
normal preferred structural bonding arrangement of C60 molecules. Several kinds of spectral changes are clearly
observed as doses increase. More accurately, one should notice the significant intensity increase of Ag(2), a
shift of the Hg(8) line towards lower and higher frequency, gradual disappearance of the 1581 cm-1 line, gradual
appearance of Hg(7), complete disappearance of the 1340 cm-1 line. At higher doses above 5.37x1016 ions/cm2,
some Raman active modes which were not observed at low doses start to occur. This could be due to the fact
that the protons ions during their penetration, interact with the nano-rods breaking specific bonds and thereby
causing a certain re-arrangement of the C60 molecules in order to satisfy the bonding configuration on the nanorods. The most intense modes of C60 molecule around 487 cm-1 and 1464 cm-1 correspond to the pentagon pinch
modes Ag (1) and Ag (2) respectively. One could notice that the intensity of these pentagon pinch modes
increase with the proton dose sustaining the hypothesis of the induced structural re-arrangement by the protons
as they go through the nano-rods of C60. In view of these Raman observations, one could partially conclude that
at low dose of about 1.79 x1016 ions/cm2, the nano-rods behave like graphite which could mean that the protons
have induced a significant bonds breaking. At doses of about 8.96x10 16 ions/cm2, most of the Raman peaks of
C60 nano-rods are clearly observed suggesting that the heat flow around the damaged zones results in structural
re-arrangement.
These Raman investigations were complemented by
X-ray diffraction measurements. Figure 3 reports the
corresponding room temperature patterns of the
irradiated nano-rods. Preliminary investigations of the
un-irradiated nano-rod samples and of as-purchased
powder indicated the preferential texture orientation along
the (111) direction. Concerning the irradiated nano-rod
sample, the variation of the intensity of the various
observed Bragg peaks, namely (111), (220), (311), (222),
(422) and (511) changes in a peculiar way.
Below
5.37x1016 ions/cm2, and excluding the (422) Bragg peak,
Figure 3: Room temperature X-ray diffraction
patterns of the different irrdiated C60 nano-rods.
the intensity of the various other Bragg peaks decreases
while it increases above the mentioned dose. Specifically, such an evolution is obvious in the case of the (111)
peak which is naturally assigned to the fcc formation of C60 in the (100) direction. This could be caused by a
147
rearrangement of the C60 molecules in order to satisfy the bonding configuration on the rod during the proton
irradiations. A more precise investigation of the angular position of the (111) peak located at about 10.9 degrees
shows a sensitive angular shift. As the doses are increased above the likely threshold dose of 5.37x1016
ions/cm2, the (111) and (422) Bragg peak intensities increase and decrease respectively. As in the case of
Raman experiments, the dose within the range of 5.37x1016 ions/cm2 would be a threshold value from which there
is a structural re-arrangement. To reach a clear conclusion about the type of rearrangements taking place after
the proton irradiations, EXAFS and XANES measurements are required to identify the nature and possibly the
process of rearrangements and defects of the C60 molecules within the rod structure.
References
1. C S Sundar, A Bharathi, Y Hariharan, et al., Sol. State, Commun. 84 (1992) 823.
2. U D Venkateswaran, M G Schall, Y Wang, et al., ibid. 96 (1995) 951.
3. K Pichler, M G Harrison, R H Friend, et al., syn. Met. 55 (1993) 3229.
4. C Wen, J Li, K Kitazawa, et al., Appl. Phys. Let. 61 (1992) 2162.
5. Y Kopelevich and P Esquinazi, arXiv:cond-mat/0609497 1 (2006).
6. A A Ovchinnikov et al., J. Mol. Struct. (Theochem) 83 (1991) 133.
7. A Hayashi, S Yamamoto, et al., R&D Review of Toyota CRDL Vol. 40 No.1.
8. A Talyzin, A Dzwilewski, et al. arXiv :cond-mat/0602306 1 (2006).
9. B Telling, C P Ewels, et al., Nature Materials 2 (2003) 333.
10. A V Krasheninnikov and F Banhart, Nature Materials 6 (2007) 723.
11. R Saito, M Fujita, G Dresselhaus, and M S Dresselhaus, Appl. Phys. Lett. 60 (2006) 2204.
12. J W Mintmire, B I Dunlap, and C T White, Phys. Rev. Lett. 68, (1992) 631.
13. M Schluter, M Lannoo, M Needels, G A Baraff, and D Tomanek, Phys. Rev. Lett. 68 (1992) 526.
14. N Hamada, S I Sawada, and A Oshiyama, Phys. Rev. Lett. 68 (1992) 1579.
15. K L Narayanan, N Kojima, et al., Journal of Materials Science, 34 (1999) 5227-5231.
16. S Mathew, B Satpati, B Joseph, and B N Dev, arXiv:cond-mat/0503315 2 (2005).
17. V Yazyev, I Tavernelli, U Rothlisberber, and L Helm, arXiv:cond-mat/0703655 1 (2007).
18. D W Boukhvalov and M I Katsnelson, arXiv: arXiv: cond-mat/0712.2928 1 (2007).
19. A Kumar, D K Avasthi, et al., Physical Review B 74 (2006) 153409.
20. P Esquinazi, D Spemann, et al., Physical Review Letters, 91 (2003) 227201.
21. A Kis, G Csanyi, J -P Salvetat, T -N Lee, E Couteau, A J Kulik, W Benoit, J Brugger, and L Forro, Nature
Materials 3 (2004) 153.
22. C Miko, M Milas, J W Seo, E Couteau, N Barisic, R Gaal, and L Forro, Appl. Phys. Lett. 83 (2003) 4622.
.
148
2.6 iThemba LABS (Gauteng)
2.6.1 Energy Calibration of the Refurbished 6 MV EN Tandem Accelerator of iThemba
LABS (Gauteng) for Nuclear Physics Experiments
C O Kureba1, 2, M Jingo1, 2, J Carter2, E Sideras-Haddad1, 2
1iThemba
2School
LABS (Gauteng), Private Bag 11, WITS 2050, Johannesburg, South Africa
of Physics, University of the Witwatersrand, P O WITS 2050, Johannesburg, South Africa
Refurbishment of the 6 MV EN Tandem accelerator of iThemba LABS (Gauteng) has been completed. Light
heavy-ion beams have been delivered to the nuclear structure beam-line, the C-Line, which has been in operation
since the commissioning of the accelerator in the 1970‟s. The newly upgraded 860C sputter ion source with a
graphite target was used to carry out an inflection magnet scan. Experimental data were analysed, and the
identified ions are shown in Figures 1a and 1b.
Figure 1a: Log plot of ion source species identified.
Figure 1b: Linear plot of ion source species identified.
Nuclear scattering experiments require the energy of the incident beam to be known to within about 20 keV in
order to determine possible resonance energies. An additional requirement is the quick change of beam energy
without changing the stability conditions. We report on two different calibration techniques of the iThemba LABS
(Gauteng) 6 MV EN Tandem accelerator momentum-analysing magnet system.
In the first method, -particle energies measured at a large backward-scattering angle (θlab = 170º) from the
12C(16O,)24Mg*
(1.3686 MeV) reaction exciting low-lying states in 24Mg (see Figure 2a) were used to infer the
energy of the incident 16O beam [1]. The reaction-product -particle energy was obtained by bracketing (see
149
Figure 2b) with known energies from a thin 241Am -source. An analyser magnet constant was determined from
the analysis of the experimental results.
Figure 2b: Enlarged view of the alpha group for the
24Mg level at 1.3686 MeV of excitation bracketed by
the main alpha peaks from a 241Am source.
Figure 2a: Measured energy spectrum from the 12C(16O,)24Mg* reaction
The second method involves the use of the 27Al(p,n)27Si reaction to determine the proton beam energy from the
known sharp neutron-emission threshold of 5.802 ± 0.005 MeV [2]. More details of the technique can be found in
References [2, 3]. Figure 3 shows part of the experimental set-up for this calibration method. The beam energy
measurements will be used to determine another value for the analyser magnet constant. It should be noted that
the silicon surface-barrier detector, 12C target and
241Am
source were set up for the first method in the large
scattering chamber.
27Al Target
Neutron
Position
Rem Detector
Faraday Cup
Eberline Neutron
Counter
Large
Scattering Faraday Cup
Chamber
Current Integrator
Pre-Amplifier
Figure 3: Part of the C-line experimental set-up to measure neutron yield from the 27Al(p,n)27Si reaction
150
The calibrated momentum-analyzing magnet system will then be used to determine the absolute energies of the
various ion beams from the accelerator with a high degree of accuracy.
References
1. D K Olsen, K A Erb, C M Jones, W T Milner, D C Weisser and N F Ziegler, Nucl. Instr. and Meth. in Phys.
Res. A254 (1987) 1-6.
2. J C Overley, P D Parker and D A Bromley, Nucl. Instr. and Meth. 68 (1969) 61-69.
3. E M Bernstein, Geometry effects in precise threshold determinations, Phys. Rev. C15 (1976) 1592-594.
2.6.2 Set up of the Nuclear Physics Beam line on the 6 MV EN Tandem Accelerator of
iThemba LABS (Gauteng)
M Jingo1, 2, C O Kureba1, 2, J Carter2, E Sideras-Haddad1, 2
1iThemba
2School
LABS (Gauteng), Private Bag 11, WITS 2050, Johannesburg, South Africa
of Physics, University of the Witwatersrand, P O WITS 2050, Johannesburg, South Africa
The nuclear physics beam line (C-line) at the Tandem accelerator of iThemba LABS (Gauteng) has been
completely rebuilt.
A preliminary optical alignment has been performed.
New pumps have also been
incorporated in the line and scattering chambers.
Currently under way is an investigation to determine the characteristics of the high-resolution ΔE-E gas-ionisation
detector which will later be used for nuclear particle identification in light heavy-ion scattering reactions. A typical
example of the measured ∆E-E spectrum that was measured using the gas ionisation chamber of the C-line is
shown in Figure 1. The previous operating conditions for the ∆E-E gas-ionisation detector were described in [2],
however, now there is a need to obtain new conditions, having changed the gas used in the ∆E part from argon /
methane to iso-butane. In addition, the gas delivery system has been rebuilt to incorporate an electronic
pressure control system and gas flow regulator, whose operational
requirements should be better than ± 5% stability at a differential
pressure of 1 kPa. We intend to ascertain the long-term stability
(over a 24-hour period) of the new gas delivery system. In order to
determine the characteristics of the ΔE-E gas-ionisation detector,
various heavy-ion beams (9Be, 12C, 16O) will be scattered off a solid
tantalum target to generate a continuum of energies at a forward
scattering angle. The plateau region for the ∆E detector will be
determined by varying the voltages applied to the anode, grid and
cathode. Figures 2 and 3 show the schematic diagram of the ∆E-E
gas-ionisation detector and the set-up of the newly re-built gas
delivery system, respectively.
151
Figure 1: Two-dimensional ∆E-E spectrum of 9Be
on 9Be at ELab = 16 MeV and θLab = 17.5º [1].
References
1. R L Wabwile, Inelastic excitation of unbound states in Bosonic (6Li + 6Li) and Fermionic (9Be+ 9Be) Heavy-ion
systems, MSc Research Report, University of the Witwatersrand, (2004).
2. B O Carragher, Heavy ion -transfer reactions, MSc Dissertation, University of the Witwatersrand, (1981).
Figure 2: A schematic diagram of the ∆E-E gas-ionisation detector.
Figure 3: A picture showing the set-up of the gas delivery system to the gas-ionization chamber.
152
3. PERFORMANCE SUMMARY
153
3.1 Directorate Level Organisation
NRF
Relations with …
Director’s Council
Human Resources
Laboratory Director’s office
Government
Director
Finance
Secretariat
Higher Education
Deputy Director
International Orgs.
Business Admin
User groups
Project Management
Scientific Committees
“iTPTC”
Radio Active Beams
…
Groups/Departments
Accelerators
Gauteng
Technical
Support
Medical
Radiation
Materials
Research
154
Physics
Information
Technology
Radionuclides
Science
Awareness
…
Financial Performance
3.2 Financial Performance
3.2.1 The table below summarises the Financial Performance of iThemba LABS for 2008/09.
Budget
R’000’s
Actuals
R’000’s
Latest Forecast
R’000’s
133 915
109 296
5 648
14 750
4 221
144 795
109 296
18 977
11 906
4 616
155 096
110 796
17 525
14 750
12 025
(134 148)
(149 481)
(153 430)
(41 036)
(80 749)
(12 363)
(47 985)
(82 616)
(18 880)
(46 644)
(82 535)
(24 251)
Net Deficit
(233)
(4 686)
1 666
Cumulative Deficit
(551)
(7 036)
(684)
Income
Core Grant
Internal Grants
Radionuclide Revenue
Other
Expenditure
Net operating expenses
Salaries
Capital Expenditure
3.2.2 The (R7m) deficit was anticipated due to the need to prefund the Beam Splitter Project (R3,5m) and loss of
Revenue of (R3,0m). The R2m received in advance from the NRF for research equipment for the Dubna
Collaboration is offset by outstanding funds for Conferences (R1m) and the AMS Ion Source (R1,4m).
The recovery of the costs for the Beam Splitter has been included in the 2009/10 budget. However, the (R3m)
loss in revenue will need to be offset with increase in revenue and reduction in costs.
3.2.3 Internal grants increase of R13,3m is attributable to:
NEP Funding: Research Equipment (Dubna)
Salary Costs Adjustments from NRF
2005 Gauteng Grant from NRF
Researchers‟ Incentive – 2007 Outputs
Outstanding Ion Source Grant (NEP)
Capital Grant: UPS Batteries Replacement
R’m
2,0
1,6
1,5
1,0
2,3
5,2
13,6
 The DST has approved R5,5m for equipment for the Dubna Collaboration. The R2m is part payment as a deposit is
required on placement of order.
 Salary Costs adjustments refer to R1m for the higher than budget April salary increases (total additional costs R1,5m
per annum) and R0,6m for special once-off bonuses.
155
Financial Performance
 The UPS batteries, which were rapidly reaching the end of their useful operating life, required urgent replacement.
The NRF secured additional capital funds from the DST for this project.
3.2.4 Due to an unforeseen production target failure late February, two large export orders were lost (R2,5m). The
facility was successfully repaired by end March and production resumed.
3.2.5 The Insurance Underwriters rejected the UPS Motor Repair claim of R1,7m, these costs had to be absorbed by
iThemba LABS. An anticipated ex gratia payment of R0,5m did not materialise due to non-renewal of the policy
as a result of excessive increases proposed for the annual premium.
3.2.6 The external ALC grants for international collaborations have been included with other income.
3.2.7 Total Operating Costs of (R67m) reflect an increase of (R8,7m) or 15% relative to the original budget. Major
costs not included in the budget are:

(R0,7m) for conferences, mainly the Synchrotron Conference in February 2009.

(R1,3m) for the RSA/CERN collaboration, the DST awarded R2m in March 2008.

(R1,7m) for the UPS Motor Repairs.

(R1,0m) additional Production and Repairs costs within Radionuclide Production.
 Travel Costs increased by (R1,1m) excluding RSA/CERN and Conferences; this relates to the Algeria collaboration
financed by the DST and Africa / European collaborations funded by the African Laser Centre.

(R2,2m) of the total operating expense variances refer to the increase in the Depreciation charge. Salvage values
were reduced end March 2008 thus increasing this charge.
 The increase in Power Costs of (R0,3m) is well below the tariff increase from Eskom due to the reduction in
consumption, mainly as a result of reducing beam time available for Proton Therapy which requires a high beam
energy of 200MeV.
3.2.8 (R2m) of the additional salary costs are due to the higher April salary increase (R1,5m) and the special bonuses
(R0,5m).
3.2.9 The Capital expenditure increase of (R6,5m) arises from the following projects which were initiated mainly due
to non-core grant funding:
UPS Batteries Replacement
Beam Splitter
NEP Projects not Completed
AMS Ion Source
R’m
(5,2)
(3,5)
3,0
(1,4)
(6,9)
156
Funded Internally
KPI‟s
3.3 Internal Key Performance Indicators (KPI’s)
Listed below are the major KPI‟s used to manage the operations of iThemba LABS.
Table 1: Major KPI‟S
Actual
2007/08
Target
2008/09
Actual
2008/09
Target
2009/10
63,0
59,9
30,9
0
311
473
12521
70,0
68,0
45,0
50,0
325
500
14500
61,8
67,4
36,4
33,3
422
603
11 906
71,0
68,0
35,0
40,0
350
500
20500
iThemba LABS Research Papers
Presentations at International Conferences
Number of Collaborators
% Black SA Users & Collaborators
Total Number of Postgraduate Students
% Black Postgraduate Students
Number of MSc. & Doctoral Degrees obtained
Number of African Collaborations
73
56
538
35
199
84,9
40
44
80
85
450
35
205
86,0
52
22
85
72
608
37
185
80,0
19
54
75
55
450
35
200
85,0
35
30
International Users & Collaborators
Number of International Collaborative Projects
Scientists from African Countries using iThemba LABS
281
90
53
250
85
70
328
126
61
250
85
50
Other Income as % of Core State Grant
IT Costs as % of Total costs
Capital Expenditure as % of Annual Depreciation Charge
23,1
12,3
54,4
22,5
11,6
73,2
30,7
11,1
98,8
25,2
12,7
87,7
Number of Visitors
6746
9000
10 789
9000
% Useful Beam Time (SSC)
% Useful Beam Time: Van de Graaff
% Usage Van de Graaff
% Useful Beam Time (Gauteng)
Patient Income: Proton/Neutron Therapy & LINAC (R‟000‟s)
Income: Hospital
(R‟000‟s)
Radionuclide Income (R‟000‟s)
157
Human Resources
3.4 Human Resources
3.4.1 The Contribution of the Human Resources Functionary to iThemba LABS’ Strategic
Priorities
The past financial year has been characterised by immense pressure and change. An internal audit report received
during the third quarter of the financial year highlighted some significant areas for improvement. Finance, together with
HR embarked on a strategy to address these issues, which have also led to a greater awareness and focus on
compliance. Several audit findings have been addressed to date, thanks to the commitment by the Senior Management
team, but ongoing commitment will be required to resolve all findings by the end of the 2009/2010 financial year.
Although staff turnover remains a concern, the 2008/2009 financial year has also been characterised by quite a number
of successes in other areas, such as Succession Management. We have seen several internal promotions of our staff in
critical areas, i.e. Accelerator and Engineering Department. In addition our Nuclear Physics skills pipeline initiative
continued to grow, and our first Medical Physicist (from our skills pipeline) was appointed at the beginning of 2009.
We have also seen the finalisation of a major job evaluation project started some two years ago. The Director
established an internal grading committee, chaired by the most senior members of staff, to ensure iThemba LABS‟
ongoing commitment to fair and transparent job evaluation processes.
3.4.2 Staff Representation
Employment Equity representation for the said financial year remains unchanged at 66% with gender representing 28%
Designated
Occupational Level
Senior management
Professionally qualified and
experienced specialists and
mid-management
Skilled
technical
and
academically
qualified
workers, junior management,
supervisors, foremen and
superintendents
Semi-skilled
and
discretionary decision-making
Unskilled
and
defined
decision-making
TOTAL
Male
Afr
Clrd
Ind
Total
2
1
1
4
10
12
2
24
2
7
17
34
1
52
6
15
28
43
44
75
123
4
White
Male
Female
Afr
Clrd
Total
White
0
4
11
20
45
9
1
16
21
17
21
5
43
25
37
17
79
158
Ind
0
White
Non Designated
Foreign
Nationals
Male
Female
Grand Total
of our workforce. The table below displays a detailed staff profile for 2008/09:
8
12
2
103
89
86
70
12
2
286
Human Resources
Proportion of researchers to total staff:
iThemba LABS
Research
Staff
Percentage
49
286
17%
2008/09
3.4.3 Staff Movements
The following table displays the staff movements for the period 1 April 2008 to 31 March 2009.
Male
Non - Designated
Female
White Male
Foreign Nationals
Grand Total
Designated
Afr
Clrd
Ind
Total
Afr
Clrd
Ind
White
Total
White
Male
Female
Recruitment
12
9
0
21
5
9
0
0
14
8
3
1
47
Resignations
5
7
1
13
3
4
1
0
8
5
1
1
28
0
1
7
2
Retirements
Contracts Expired
0
6
1
Dismissals
0
7
1
Deaths
1
TOTAL
12
9
1
2
5
1
1
17
1
0
1
1
0
1
22
5
9
1
0
15
8
2
1
48
3.4.4 Training And Skills Development
There are currently 30 members of staff enrolled for part-time studies and some 64 employees attended various training
courses during the year.
Staff Profile in terms of post-graduate qualifications:
Non Designated
BUSINESS UNIT
Male
Total
White
Male
Female
4
5
24
8
2
48
0
2
1
1
6
3
0
2
6
34
White
Male
Female
Afr
Clrd
Ind
Total
Afr
Staff with PhD
4
2
3
9
1
Staff enrolled for PhD
3
Staff with Master's
6
Clrd
Ind
3
1
7
Staff enrolled for
Master's
Total
White
Grand Total
Designated
1
0
13
3
3
19
1
1
159
0
4
Foreign
Nationals
6
1
18
2
12
3
74
Human Resources
Staff who attended training during 2008/2009:
Business Unit iTHEMBA LABS
Occupational
Group
Senior Officials &
Managers
Professionals
Technicians &
Associate
Professionals
Clerks
Craft & Related
trades
Plant & Machine
Operators
Elementary
Occupations
Contract
employees
Non-permanent
employees
TOTAL
Male
Clrd
Ind
Total
Afr
Clrd
0
0
1
1
0
0
2
2
17
5
22
0
5
White
Male
Female
Afr
2
Non - Designated
Ind
White
Foreign
Nationals
Female
Grand Total
Designated
Total
White
Male
1
1
1
1
1
1
3
6
2
2
4
8
34
0
0
0
4
0
7
0
0
0
0
3
3
0
3
2
2
0
2
4
6
1
1
25
13
1
2
2
2
39
4
6
0
0
10
2
14
9
1
0
64
3.4.5 Key Human Resources Challenges
 The start of the new financial year sees the implementation of the NRF‟s revised Integrated Performance
Management System and acknowledges that ongoing communication and training will be key to staff
acceptance of this system.
 The job evaluation process for all management positions remains outstanding. A recent review of the
management structures at iThemba LABS has delayed the process of having accurate and well-defined job
profiles in place for all members of management. It is envisaged that the exercise will be completed by the
end of 2009/2010.
 The internal audit report findings mentioned earlier remains a critical key performance area for the
organization. Ongoing and cogent attention will be given to ensure that corrective actions are implemented
during the new financial year which will require the explicit commitment by all management and staff.
160
4. APPENDICES
161
Appendices
4.1 Publications and Reports*
a problem in post-agricultural lands. Scientia
Horticulturae 117 (2008) 357.
*(Publications
and reports on research done (fully or in
part) at iThemba LABS by external users and/or
members of staff, as well as work done elsewhere in
which members of staff participated)
6. K Vogel-Mikuš, M Regvar, J MesjaszPrzybyłowicz, W J Przybyłowicz, J Simčič, P
Pelicon, M Budnar.. Spatial distribution of Cd in
leaves of metal hyperaccumulating Thlaspi
praecox using micro-PIXE. New Phytologist 179
(2008) 712.
Publications in Refereed Journals
7. K Vogel-Mikuš, J Simčič, P Pelicon, M Budnar, J
Mesjasz-Przybyłowicz, W J Przybyłowicz, M
Regvar. Comparison of essential and nonessential element distribution in leaves of the
Cd/Zn hyperaccumulator Thlaspi praecox as
revealed by micro-PIXE. Plant Cell &
Environment 31 (2008) 1484.
1. G Busetti, C Goletti, A Violante, P Chiaradia and
T Derry. The 2x1-reconstructed Cleavage
Surface of Diamond: A Challenging Test for
Experiment and Theory. Superlattices and
Microstructures
(2009),
doi:10.1016/
j.spmi.2009.01.012.
2. T E Derry, E K Nshingabigwi, C M Levitt and J
Neethling. Cross-section Transmission Electron
Microscopy of the Ion Implantation Damage in
Annealed Diamond. Nuclear Instruments and
Methods B, in press (2009).
8. M M Rost-Roszkowska, I Poprawa, J Klag, P
Migula,
J
Mesjasz-Przybyłowicz,
W
Przybyłowicz. Degeneration of the midgut
epithelium in Epilachna cf. nylanderi
(Insecta,Coccinellidae): apoptosis, autophagy,
and necrosis. Canadian Journal of Zoology 86
(2008) 1179.
3. J D Comins, G O Amolo, T E Derry, S H Connell
and M J Witcomb. Ion Beam Induced Defects in
Solids Studied by Optical Techniques. Nuclear
Instruments and Methods B, in press (2009).
9. M Topić, C A Pineda-Vargas, R Bucher, H E du
Plessis, B Breedt, V Pischedda, S Nxumalo, C I
Lang, High temperature study on thin aluminium
coatings deposited onto thick platinum
substrates. Surface & Coatings Technology 203
(2009) 3044-3048.
1. M Maaza, C Herculano, S Ekambaram, O
Nemraoui, U Buttner, J B Kana Kana and N
Manyala. Pulsed Laser Liquid Interaction:
Synthesis of Pt, Au, Ag and Cu nanosuspensions and their stability. International
Journal of Nanoparticles 1 (2008) 212-223.
10. A M Korsunsky, W J Vorster, S Y Zhang, M
Topić, A Venter. A beam-bending eigenstrain
analysis of residual elastic strains in multi-scan
laser-formed steel samples. Journal of Eng.
Science 222 (2008) 1-11.
2. J B Kana Kana, J M Ndjaka, P Owono Ateba, B
D Ngom, N Manyala, O Nemraoui, A C Beye, M
Maaza. Thermochromic VO2 thin films
synthesized by rf-inverted cylindrical magnetron
sputtering. Applied Surface Science 254 (2008)
3959.
Migula,
J
W
Przybyłowicz. Differentiation of regenerative
cells in the midgut epithelium of Epilachna cf.
nylanderi (Mulsant 1850) (Insecta, Coleoptera,
Coccinellidae). Acta Zoologica (in press).
3. M Williams, C A Pineda-Vargas, E V Khataibe, B
J Bladergroen, A N Nechaev, V M Linkov,
Surface functionalization of porous ZrO2-TiO2
membranes using -aminopropyltriethoxysilane
in palladium electroless deposition. Applied
Surface Science 254 (2008) 3211–3219.
12. J Mesjasz-Przybyłowicz, A Barnabas, W
Przybyłowicz. Root ultrastructure of Senecio
coronatus genotypes differing in Ni uptake.
Northeastern Naturalist (in press).
13. M Williams, A N Nechaev, M V Lototsky, V A
Yartys, J K Solberg, R V Denys, C A PinedaVargas, Q Li, VM Linkov. Influence of
aminosilane surface functionalization of rare
earth hydride-forming alloys on palladium
treatment by electroless deposition and
hydrogen sorption kinetics of composite
materials. Mat. Chem. & Phys. (2009) (in press).
4. R B Heimann, T P Ntsoane, C A Pineda-Vargas,
W J Przybylowicz, M Topic.
Biomimetic
formation of hydroxyapatite investigated by
analytical techniques with high resolution.
Journal of Materials Science: Materials in
Medicine 19 (2008) 3295-3302.
5. H-J Hawkins, H Hettasch, L Louw, C O‟Brian, J
Mesjasz-Przybyłowicz, W Przybyłowicz, M D
Cramer. Phosphorus toxicity in the Proteaceae:
162
Appendices
14. F Roelofse, L D Ashwal, C A Pineda-Vargas, W
J Przybylowicz. Enigmatic textures developed
along plagioclase-aigite grain boundaries at the
base of the Main Zone, Northern Limb, Bushveld
Complex – evidence for late stage melt
infiltration into a nearly solidified crystal mush.
South Afr. J. Geology (2009) (in press).
7. H Fujita, G P A Berg, Y Fujita, J Rapaport, T
Adachi, N T Botha, H Fujimura, K Fujita, K
Hara, K Hatanaka, J Kamiya, T Kawabata, T
Nakanishi, R Neveling, N Sakamoto, Y Sakemi,
F D Smit. High resolution study of isovector
negative parity states in the 16O(3He,t)16F
reaction at 140 MeV/nucleon. Phys. Rev. C79
(2009) 024314.
Physics Group
Radioisotope Production Group
1. T R Saito, N Saito, K Starosta, J Beller, N
Pietralla, H J Wollersheim, D L Balabanski, A
Banu, R A Bark, T Beck, F Becker, P
Bednarczyk, K H Behr, G Benzoni, P G Bizzeti,
C Boiano, A Bracco, S Brambilla, A Brunle, A
Burger, L Caceres, F Camera, F C L Crespi, P
Doornenbal, A B Garnsworthy, H Geissel, J
Gerl, M Gorska, J Grebosz, G Hagemann, J
Jolie, M Kavatsyuk, O Kavatsyuk, T Koike, I
Kojouharov, N Kurz, J Leske, G Lo Bianco, A
Maj, S Mallion, S Mandal, M Maliage, T Otsuka,
C M Petrache, Z S Podolyak, W Prokopowicz,
G Rainovski, P Reiter, A Richard, H Schaffner,
S Schielke, G Sletten, N J Thompson, D Tonev,
J Walker, N Warr, O Wieland, Q Zhong. Yrast
and non-yrast 2+ states of 134Ce and 136Nd
populated in relativistic Coulomb excitation.
Phys. Lett. B669, (2008) 19.
1. N P van der Meulen, T N van der Walt,
G F Steyn, F Szelecsényi, Z Kovács,
C M Perrang, H G Raubenheimer.
The
production of 88Y in the proton bombardment of
natSr: new excitation and separation studies.
Appl.
Radiat.
Isot.
(2009),
doi:
10.1016/j.apradiso.2009.02.058.
1. F J A I Vernimmen, Z Mohamed, J P Slabbert,
J Wilson. Long term results of Stereotactic
Proton Beam Radiotherapy for Acoustic
Neuromas. Int. J of Radiation Therapy and
Oncology: 90 (2009) 208.
2. J M Akudugu, J P Slabbert. Modulation of
radiosensitivity in Chinese hamster lung
fibroblasts by cisplatin. Canadian Journal of
Physiology and Pharmacology 85(5) (2008) 257263.
2. B G Carlsson, I Ragnarsson, R Bengtsson, E O
Lieder, R M Lieder, and A A Pasternak. Triaxial
shape with rotation around the longest principal
axis in 142Gd. Phys. Rev C78 (2008) 034316.
3. E A Lawrie, P A Vymers, J J Lawrie, C H Vieu,
R A Bark, R Lindsay, G K Mabala, S M
Maliage, P L Masiteng, S M Mullins, S H T
Murray, I Ragnarsson, T M Ramashidzha, C
Schück, J F Sharpey-Schafer and O Shirinda.
Possible chirality in the doubly-odd 198Tl
nucleus: Residual interaction at play. Phys.
Rev. C78 (2008) 021305 (R).
Reports
1. K Mathapo, N Steenkamp, J Slabbert.
SunSpace and Information Systems: Test
Report for Si2110 DBV-S demodulator
irradiation.
4. B Buck, A C Merchant, S M Perez. Negative
parity bands in even-even isotopes of Ra, Th, U
and Pu. J.Phys.G: Nucl. Part. Phys. 35 (2008)
085101.
5. S M Perez, W A Richter, B A Brown, M Horoi.
Correlations between magnetic moments and
 decays of mirror nuclei. Phys. Rev. C77
(2008) 064311.
6. A A Cowley, J Mabiala, E Z Buthelezi, S V
Förtsch, R Neveling, F D Smit, G F Steyn, J J
van Zyl. Analyzing power distribution in the
12C(p,p)8Be(g.s) reaction at an incident
energy of 100 MeV. Eur. Phys. Lett. 85 (2009)
22001.
163
Appendices
4.2 Conference Proceedings
residual gas in a cyclotron beam line. EPAC08,
Genoa, Italy, 23 – 27 June 2008.
3. R W Thomae, P J Celliers, J L Conradie, J L G
Delsink, J G de Villiers, H du Plessis, D T
Fourie, M Sakildien. Status of new electron
cyclotron resonance ion sources at iThemba
LABS. 18th International Workshop on ECR Ion
Sources, Chicago, Illinois, USA, September 1518, 2008.
1. M Madhuku, D Gxawu, I Z Machi, S H Connell, J
M Keartland, S F J Cox and P J C King.
Thermal ionisation of bond-centred muonium in
diamond? Physica B: Proceedings of the 11th
International Conference on Muon Spin
Rotation, Relaxation, & Resonance (µSR 2008),
Tsukuba, Japan, 21-25 July 2008.
4. J L Conradie. The Accelerator Facilities of the
National Research Foundation in South Africa.
XXXIth
Russian
Particle
Accelerator
Conference (RuPAC 2008), Zvenigorod,
Moscow, September 28 - October 3, 2008.
2. M A G Andreoli, R J Hart, G R J Cooper and S J
Webb. The Morokweng impact crater, South
Africa: A complex, multiring structure with A
~130 km radius external ring and asymmetric
radial sectors. Large Meteorite impacts and
Planetary evolution: Special papers, Vredefort,
South Africa. 17-24 August 2008.
1. J B Kana Kana, J M Ndjaka, N Manyala, O
Nemraoui, A C Beye and M Maaza. Combined
Themochromic
and
Plasmonic
Optical
responses in novel nanocomposites Au-VO2
films prepared by RF inverted cylindrical
magnetron sputtering. AIP Proceedings 1047
(2008) 103.
3. A Galdeano, M A G Andreoli and R J Hart.
Magnetic imaging of the Vredefort Dome:
Implications for the size and geometry of the
Vredefort crater. Large Meteorite impacts and
4. M A G Andreoli, W D Maier, I McDonald, S J
Barnes, F Roelofse, C M Cloete, C Okujeni and
R J Hart. Siderophile minerals in the melt sheet
of the Morokweng impact crater, South Africa:
Similarities and differences with the Sudbury
deposits.
Large Meteorite impacts and
2. N Manyala, B Ngom Diop, J B Kana Kana, R
Bucher, M Maaza and J F DiTusa.
Characterization of Fe1-xNd1-xNiO3 thin films
deposited via pulsed laser deposition, AIP
Proceedings 1047 (2008) 127-129.
3. S Lafane, T Kerdja, A Abdelli-Messaci, S Malek
and M Maaza. Laser ablated plasma dynamics
for Sm1-xNdxNiO3 thin films deposition. AIP
Proceedings 1047 (2008) 103-106.
5. D E Moser, W J Davis, S Reddy, R L Flemming
and R J Hart. Zircon U-Pb age discordance and
trace element alteration due to deep, postimpact flow.
Implications for planetary
chronology
Goldschmidt
Conference.
Vancouver, Canada, September 2008.
4. B D Ngom, J B Kana Kana, O Nemraoui, N
Manyala, M Maaza, R Madjoe, and A C Beye.
Infrared active Sm 1-xNd 1-xNiO3 based nanoswitchings for high power lasers, AIP
Proceedings 1047 (2008) 280-283.
5. M Maaza. Nano-scaled materials and photonics
applications, AIP Proceedings 1047 (2008) 49.
Accelerator Group
1. Z Kormány, K Juhász, J L Conradie, J L G
Delsink, D J Fourie, J V Pilcher, P F Rohwer.
Development of non-destructive beam current
measurement for the iThemba LABS
Cyclotrons. EPAC08, Genoa, Italy, 23 – 27
June 2008.
6. C A Pineda-Vargas, M E M Eisa, A L Rodgers.
Characterization of human kidney stones using
micro-PIXE and RBS: A comparison study
between two different populations. Proceedings
of the first international conference on
biomedical applications of high energy ion
beams, 30th July-2nd August 2007, Guilford, UK,
ISSN 0969-8043 (2009) 464-469.
2. J Dietrich, C Boehme, T Weis, L Anthony, A H
Botha, J L Conradie, J A Crombie, J L G
Delsink, J G de Villiers, J H du Toit , D T
Fourie, H W Mostert, P F Rohwer, P A van
Schalkwyk. Non-destructive beam position and
profile measurements using light emitted by
164
Appendices
Migula,
J
W
Przybyłowicz. Autophagy in midgut epithelial
cells of Epilachna cf. nylanderi (Insecta,
Coccinelidae). Journal of Morphology 269
(2008) 1494.
LABS. Nucl. Instrum. Meth. Phys. Res. A 590
(2008) 114-117.
4. B Buck, A C Merchant, S M Perez. Recurring
nuclear band spectra. 9th Internat. Conf. on
Clustering Aspects of Nuclear Structure and
Dynamics. Jour. of Phys.: Conference Series
111 (2008) 012011.
Migula,
J
W
Przybyłowicz: Stem cells of the midgut
epithelium of Epilachna cf. nylanderi (Insecta,
Coccinelidae). Journal of Morphology 269
(2008) 1495.
5. B Buck, A C Merchant, S M Perez. Octupole
bands in even isotopes of Ra, Th, U and Pu. 9th
Internat. Conf. on Clustering Aspects of Nuclear
Structure and Dynamics. Jour. of Phys.
Conference Series 111 (2008) 012041.
9. S Kortyka, R Puzniak, A Wisniewski, H W
Weber, T B Doyle, T Q Cai and X Yao.
Influence of low-level Pr substitution on the
superconducting properties of YBa2Cu3O7-d
single crystals. Journal of Physics: Conference
Series 150 (2009) 052123.
6. M Lipoglavšek, R A Bark, E A Gueorguieva, J J
Lawrie, E O Lieder, R M Lieder, E Lindbo
Hansen, S M Mullins, S S Ntshangase, P Papka,
T Petrovic and M Vencelj. Fusion – Fission in
the 86Kr+238U Reaction. AIP Conf. Proc. CP1012,
Frontiers in Nuclear Structure, Astrophysics, and
Reactions: FINUSTAR 2 (2008) 386-388.
10. M Msimanga, C M Comrie, C A Pineda-Vargas,
S Murry, R Bark, G Dollinger. A Time of Flight –
Energy spectrometer for stopping power
measurements in Heavy Ion – ERD analysis at
iThemba LABS. Proceedings of the 23th
international conference on atomic collisions in
solids, 17-22 August 2008, Kruger National
Park, South Africa (2009) (in press).
7. S M Mullins, B M Nyako, J Timar, G Berek, G
Kalinka, J Gal, J Molnar, S H T Murray, R A
Bark, O Shirinda, K Juhasz, E Gueorguieva, A
Krasznahorkay, J J Lawrie, R M Lieder, M
Lipoglavšek, S S Ntshangase, P Papka, J N
Scheurer, J F Sharpey-Schafer, L Zolnai. A
DIAMANT Wedding for AFRODITE: Probing
Structure and Characterizing Reaction
Properties Via Charged – Particle-
Correlations. AIP Conf. Proc. CP1012, Frontiers
in Nuclear Structure, Astrophysics, and
Reactions: FINUSTAR 2 (2008) 404-406.
11. C Cvitanich, W J Przybyłowicz, J MesjaszPrzybyłowicz, M W Blair, E Ø Jensen, J
Stougaard. Iron, zinc, and manganese
distribution in mature soybean seeds. The
Proceedings of the International Plant Nutrition
Colloquium (Proc. IPNC) (in press).
8. E O Lieder, R M Lieder, A A Pasternak, B G
Carlsson, I Ragnarsson, R A Bark, E A
Gueorguieva, J J Lawrie, S M Mullins, P Papka,
Y Kheswa, J F Sharpey-Schafer, W Gast, and G
Duchene. DSAM Lifetime Studies for Gd – Nd
Nuclei with EUROBALL and AFRODITE. AIP
Conf. Proc. CP1012, Frontiers in Nuclear
Structure, Astrophysics, and Reactions:
FINUSTAR 2 (2008) 383-385.
Physics Group
1. F Cerutti, A Ferrari, E Gadioli, A Mairani, S V
Förtsch, J Dlamini, E Z Buthelezi, H Fujita, R
Neveling, F D Smit, A A Cowley and S H
Connell. Complete fusion and break-up fusion
reactions in light ion interactions at low energies.
AIP Conf. Proc. CP947, VII Latin American
Symposium on Nuclear Physics and
Applications (2007) 287–290.
9. J F Sharpey-Schafer, S M Mullins, R A Bark, E
A Gueorguieva, J Kau, F S Komati, J J Lawrie, P
Maine, A Minkova, S H T Murray, N J Ncapayi,
P Vymers. Shape Transitional Nuclei: What can
we learn from the Yrare States? AIP Conf. Proc.
CP1012, Frontiers in Nuclear Structure,
Astrophysics, and Reactions: FINUSTAR 2
(2008) 19-25.
2. A A Cowley, J Bezuidenhout, E Z Buthelezi, S S
Dimitro, S V Förtsch, G C Hillhouse, P E
Hodgson, N M Jacobs, R Neveling, F D Smit, J
A Stander, G F Steyn, J J van Zyl. Reaction
mechanism for proton-induced 3He emission into
the continuum at incident energies between 100
and 200 MeV. Proc. Internat. Nucl. Phys. Conf.
INPC2007 (Tokyo, Japan, 3-8 June 2007), Vol.
2. Nucl. Phys. A805 (2008) 473-475.
10. S M Mullins. Accelerator Based Sciences at the
Fairest Cape of Storms and Good Hope. Proc.
of 24th Internat. Physics Congress of Turkish
Physical Society, Balkan Phys. Lett. Special
Issue (2008) 55-59.
3. N Y Kheswa, Z Buthelezi and J J Lawrie. Making
of targets for physics experiments at iThemba
165
Appendices
11. R Lindsay, R T Newman, W J Speelman. A
study of airborne radon levels in Paarl houses
(South Africa) and associated source terms,
using electret ion chambers and gamma–ray
spectrometry. Appl. Rad. and Isotop. 66 (2008)
1611-1614.
Science and Technology
10.1051/ndata:07379.
2007
DOI:
5. A Guglielmetti, D Faccio, R Bonetti,
S V Shishkin, S P Tretyakova, S V Dmitriev,
A A Ogloblin, G A Pik-Pichak, N P van der
Meulen, G F Steyn, T N van der Walt,
C Vermeulen and D McGee.
Carbon
radioactivity of 223Ac and a search for nitrogen
emission. Journal of Physics: Conference
Series 111 (2008) 012050.
12. R T Newman, R Lindsay, K P Maphoto, N A
Mlwilo, A K Mohanty, D G Roux, R J de Meijer, I
N Hlatshwayo. Determination of soil, sand and
ore primordial radionuclide concentrations by
full–spectrum
analyses
of
high–purity
germanium detector spectra. Appl. Rad. and
Isotop. 66 (2008) 855-859.
1. L August, P Willems, H Thierens, J P Slabbert
and A Vral. Automated micronucleus (MN)
scoring for population triage in case of large
radiation accidents. Radioprotection 43 (2008)
55.
13. S A Talha, R Lindsay, R T Newman, R J de
Meijer, P P Maleka, I N Hlatshwayo, N A Mlwilo
and A K Mohanty. γ-Ray spectrometry of radon
in water and the role of radon to representatively
sample aquifers. Appl. Rad. and Isotop. 66
(2008) 1623-1626.
2. L August, J P Slabbert, A Vral, J Symons.
Variations in the Radiosensitivity of Tlymphocytes of different individuals to a
therapeutic neutron beam. Radioprotection 43
(2008) 244.
14. P L Masiteng, E A Lawrie, T M Ramashidzha, J
J Lawrie, R A Bark, J Kau, F S Komati, S M
Maliage, I Mataba, S M Mullins, S H T Murray, K
P Mutshena, J F Sharpey-Schafer, P Vymers, Y
Zhang. Possible chiral bands in the doubly-odd
194Tl nucleus. Acta Phys. Polonica. B40 (2009)
657–660.
1. F Szelecsenyi, G F Steyn, Z Kovacs and
T N van der Walt. Application of Au + p nuclear
reactions for proton beam monitoring up to
70 MeV. International Conference on Nuclear
Data for Science and Technology 2007 DOI:
10.1051/ndata:07379.
2. F Szelecsenyi, G F Steyn, K Suzuki, Z Kovacs,
T N van der Walt, C Vermeulen, N P van der
Meulen, S G Dolley. Application of Zn + p
reactions for production of copper radioisotopes
for medical studies. International Conference on
Nuclear Data for Science and Technology 2007
DOI: 10.1051/ndata:07379.
3. I Spahn, G F Steyn, S A Kandil, H H Coenen
and S M Qaim. New nuclear data for production
of 73As, 88Y and 153Sm: important radionuclides
for environmental and medical applications.
International Conference on Nuclear Data for
Science and Technology 2007 DOI:
10.1051/ndata:07379.
4. G F Steyn, N P van der Meulen, T N van der
Walt and C Vermeulen. Production of carrierfree 28Mg by 50-200 MeV protons on natCl:
excitation function and target optimization.
International Conference on Nuclear Data for
166
Appendices
4.3 Conference Contributions
16. J P Blanckenberg et al. Monte Carlo simulation
of geoneutrino detection.
53rd Annual SAIP (South African Institute of
Physics) Conference, University of Limpopo,
8-12 July 2008
17. T T Ibrahim et al. On the cluster structure of
212Po.
18. I N Hlatshwayo et al. The 2007 in-situ gammaray mapping of environmental radioactivity at
iThemba LABS.
1. M Sakildien, D T Fourie, J G de Villiers, J L
Conradie, P J Celliers, J G de Villiers, J L G
Delsink, R H McAlister, C Lussi, R E F
Fenemore, M J van Niekerk, Development of the
iThemba LABS cyclotrons.
19. B A S Adam et al. Monte Carlo simulation of a
collimated fast neutron beam.
20. J Mira et al. Production of Li, Be and B isotopes
through complete and incomplete fusion
reactions in the interaction of 12C at 16.7 and
33.3 MeV/ nucleon.
2. R W Thomae, J G de Villiers, P J Celliers, D T
Fourie, M Sakildien, J L G Delsink, H du Toit, J L
Conradie, Ion Sources at iThemba LABS.
3. M Msimanga. A time of flight energy
spectrometer
for
stopping
power
measurements in heavy ion ERD analysis.
21. F D Smit et al. Where do the excited states of
the Hoyle state lie?
22. I Usman et al. Comparison of experimental and
theoretical level densities for 2+ states in 40 Ca.
4. A I Mabuda, W Przybylowicz. The
determination of boron using 11B(p,)8Be
nuclear reaction.
23. S V Förtsch et al. ALICE: a status report and
South Africa‟s involvement.
5. N
P
Mongwaketsi.
Synthesis
and
characterization of porphyrin nano-rods for the
building of light harvesting and energy transfer
systems.
24. R Neveling et al. The K600 zero degree project:
milestones and challenges.
25. S M Mullins et al. Selective massive transfer via
degrees of incomplete fusion.
6. R Bucher. The power of stereographic drawings
in education.
26. S S Ntshangase et al. Development of a recoil
detector to study exotic nuclear shapes.
7. M Makgale. Nuclear Microprobe study of the
exoskeleton role in metal elimination in
epilachna cf nylanderi.
27. E A Lawrie et al. Possible chirality in the doublyodd198TI.
8. B P Zulu. Characterization of vanadiumplatinum single and multi-layer structures.
28. T E Madiba et al. Directional correlation from
oriented states and linear polarization
measurements of gamma rays from 190Tl.
9. J Sithole. Shape anisotrophy in nano-structured
undoped ZnO for gas sensing applications.
29. S P Bvumbi et al. Spin and parity measurements
in 152Gd investigating the double vacuum and
octupole structures.
10. C
Ndlangamandla.
Synthesis
and
characterization of Fe2O3 nano-rod arrays for
H2 production.
30. T D Singo et al. The search of non-yrast states
in 160Yb.
11. B Diop Ngom. Synthesis and characterization
of ZnO nano-particles for opto-electronic
devices.
31. J J Lawrie et al. Dipole bands in 196Hg.
32. R T Newman et al. Determination of soil
primordial radionuclide concentrations by fullspectrum analyses of high-purity germanium
detector spectra.
12. M Cele. Thermochromic VO2 nano-structures,
synthesis and optical characterization.
13. S Khamlich. Synthesis and linear optical
properties of mono-disperse alpha-CrO3 nanospheres.
33. P L Masiteng et al. Possible chiral bands in the
doubly-odd 194Tl nucleus.
14. Z M Khumalo. Shape anisotrophy nanostructured undoped ZnO for gas sensing
applications.
34. M Jingo, C O Kureba, J Carter and E SiderasHaddad. Nuclear Structure studies at the
Tandem accelerator of iThemba LABS
(Gauteng).
15. C M Mtshali. Characterization of C60-porphyrins
nano-structures for solar cells applications.
167
Appendices
35. I Z Machi, M Madhuku, K G Sekonya and E
Sideras-Haddad.
Nuclear physics and
materials science research facilities at iThemba
LABS (Gauteng).
US-Africa Workshop on nanotechnology,
USAMI-Princeton external Activities, Nsukka,
Enugu State, Nigeria, 15 – 19 April 2008
1. M Maaza. Does size matter in materials.
36. G O Amolo, J D Comins and T E Derry.
Darkening Mechanism in Proton Irradiated Tin
Doped Indium Oxide (ITO) Films.
6th International Conference on Inorganic
Materials, Dresden, Germany, 28 – 30 September
2008
IS-TCOs 2008, 2nd International Symposium on
Transparent Conductive Oxides, , Hellas Crete,
Greece 22-26 October 2008
1. J B Kana Kana. Well-controlled reversible
tunable surface Plasmon resonance shift in AuVO2 thermochromic plasmonic nanostructures.
1. M Maaza. Photonic Multifunctionality and
tunability of ZnO based nanostructure.
International
Workshop
on
Materials
Microanalysis and Dating for Rock Art Studies,
Clanwilliam, South Africa, 28 September –
5 October 2008
CIMER 2009: International College on semiconducting Materials and Energy Renewables
2009, Brazzaville-Congo 1 – 5 march 2009
1. C A Pineda-Vargas. Ion Beam Analytical
Techniques in rock art studies.
1. J B Kana Kana. RF-Sputtering Synthesis of VO2.
1st International Conference on Laser Plasma
Applications in Materials Science, LAPAMS'08,
Algiers, Algeria, 23–26 June 2008
1st Yaounde International College on Novel
Materials Technologies and their Impact on
Energy,
Environment
and
Sustainable
Development, Yaounde, Cameroon, 7-12 July
2008
1. J B Kana Kana, J M Ndjaka, N Manyala, O
Nemraoui, A C Beye and M Maaza. Combined
Themochromic
and
Plasmonic
Optical
responses in novel nanocomposites Au-VO2
films prepared by RF inverted cylindrical
magnetron sputtering.
1. J B Kana Kana. Promise of Thermochromic
Nano-plasmonic.
2. J B Kana Kana. Nano-scaled materials and
photonic applications.
2. N Manyala, B Ngom Diop, J B Kana Kana, R
Bucher, M Maaza and J F DiTusa.
Characterization of Fe1-xNd1-xNiO3 thin films
deposited via pulsed laser deposition.
9th International Conference on Fine Particles:
Risks and Opportunities, Cape Town, 02 – 05
September 2008
3. S Lafane, T Kerdja, A Abdelli-Messaci, S Malek
and M Maaza. Laser ablated plasma dynamics
for Sm1-xNdxNiO3 thin films deposition.
1. M Maaza. Nano-science in
biomimics.
nature and
2. J B Kana Kana. Thermo-chromic VO2
nanostructures,
synthesis
and
optical
characterization.
4. B D Ngom, J B Kana Kana, O Nemraoui, N
Manyala, M Maaza, R Madjoe, and A C Beye.
Infrared active Sm1-xNd1-xNiO3 based nanoswitchings for high power lasers.
3. J Sithole. Synthesis and characterization of ZnO
nanoparticles for opto-electronic devices.
5. M Maaza. Nano-scaled materials and photonics
applications.
4. S Khamlich. Mono-disperse Cr2O3 nanospheres, synthesis and optical properties.
5.
Z M Khumalo. Shape anisotropy nanostructured un-doped ZnO for gas sensing
applications.
Gulf Middle-East Regional Workshop on
Nanotechnology, Muscat, Oman, 12-14 January
2008
1. M Maaza. Nano-materials for energy efficiency.
2. M Maaza. Properties of materials at the
nanoscale.
168
Appendices
23rd International Conference on Atomic
Collisions in Solids – ICACS-23, Phalaborwa,
South Africa, 17-22 August 2008.
3rd Danish Conference on Molecular Biology and
Biotechnology
“Functional
Foods
and
Nutrigenomics Nutrition in Health and Disease”,
Vejle, Denmark, 29-30 May 2008.
1. C A Pineda-Vargas. Prompt nuclear satellites
relative intensities observed from high energy
proton induced reactions.
1. C Cvitanich, D Urbanski, N Sandal, E Orlowska,
J Stougaard, E Ø Jensen, W J Przybyłowicz, J
Mesjasz-Przybyłowicz, H Brinch-Pedersen, S
Borg, P B Holm. Biofortification: bioengineering
crop plants to combat micronutrient deficiencies.
2. M Msimanga, C M Comrie, C A Pineda-Vargas,
S Murray, R Bark, G Dollinger. A Time of Flight
– Energy spectrometer for stopping power
measurements in Heavy Ion – ERD analysis at
iThemba LABS.
6th International Conference on Serpentine
Ecology, Bar Harbor, Maine, USA, 16-23 June
2008.
3. E K Nshingabigwi, T E Derry, C M Levitt and J
Neethling. Cross-section Transmission Electron
Microscopy of the ion implantation damage in
annealed diamond.
1. A
Barnabas,
J
Mesjasz-Przybyłowicz.
Ultrastructural features of root tissues of Nihyperaccumulating and non-accumulating
genotypes of Senecio coronatus.
4. K G Sekonya, E Sideras-Haddad and S J
Piketh. Characterisation of ambient atmospheric
aerosol using PIXE analysis.
2. E Orłowska, W Przybyłowicz, J MesjaszPrzybyłowicz, D Orłowski, K Turnau.
Quantitative micro-PIXE comparison of
elemental distribution in mycorrhizal and nonmycorrhizal roots of Ni-hyperaccumulating plant.
5. E Sideras-Haddad, R T Schenckel, S
Shrivastava, T Makgato, A Batra, B
Mwakikunga, R Erasmus and A Persaud.
Diamond-Like Surface Nanostructures Induced
by Slow Highly Charged Ions on Highly Oriented
Pyrolytic Graphite (HOPG).
3. M Augustyniak, K Michalczyk, W Przybyłowicz,
A Babczyńska, M Tarnawska, P Migula, J
Mesjasz-Przybyłowicz. Digestion and elemental
distribution in larval and imaginal stages of
Stenoscepa sp., a grasshopper associated with
Ni hyperaccumulating plants.
SETAC (Society of Environmental Toxicology
and Chemistry) Europe, 18th Annual Meeting,
Warsaw, Poland, 25-29 May 2008
1. D Drozdz-Gaj, P Migula, W J Przybyłowicz, J
Mesjasz-Przybyłowicz. Molecular biomarkers of
stress in the terrestrial pulmonates Cepea
nemoralis and slug Arion luisitanicus exposed
jointly or separately to cadmium, nickel and
pesticide.
XXVIII Konferencja Embriologiczna,
Poland, 14 - 17 May 2008.
International Conference on Plant-Microbial
Interactions, Kraków, Poland, 2-6 July 2008.
1. E Orłowska, D Orłowski, J MesjaszPrzybyłowicz, K Turnau. Mycorrhizal status of
plants colonizing the gold tailing in South Africa.
Wisła,
1st International Congress on Invertebrate
Morphology, Copenhagen, Denmark, 17 – 21
August 2008.
Migula,
J
W
Przybyłowicz. The role of stem cells in midgut
growth in Epilachna cf. nylanderi (Insecta,
Coccinellidae).
Migula,
J
W
Przybyłowicz. Autophagy in midgut epithelial
cells of Epilachna cf. nylanderi (Insecta,
Coccinelidae).
Migula,
J
W
Przybyłowicz. Cell death in the midgut
Coccinellidae).
Migula,
J
W
Przybyłowicz. Stem cells of the midgut
Coccinelidae).
169
Appendices
9th
International
Protea
Association,
Stellenbosch, 3-6 September 2008.
Plant Biotech, Copenhagen, Denmark, 29-30
January 2009
1. H-J Hawkins, H Hettasch, J MesjaszPrzybyłowicz, W Przybyłowicz, M D Cramer.
Phosphorus toxicity in the Proteaceae: a
problem in post-agricultural lands.
1. K M Laszczyca, D Urbanski, N Sandal, E
Orłowska, J Stougaard, E Ø Jensen, W J
Przybyłowicz, J Mesjasz-Przybyłowicz, M A
Klein, M A Grusak, S Husted, C Cvitanich.
Differential iron distribution in seeds of two
closely related legume species.
Meeting on the progress of Coordinated
Research Project F1.20.19 “Development of
nuclear microprobe techniques for the
quantitative
analysis
of
individual
microparticles”, Lisbon, Portugal, 17-19
September 2008.
Science at Synchrotrons, DST, Pretoria, 9-13
February 2009
1. W J Przybyłowicz, T Tyliszczak, A Barnabas, J
Mesjasz-Przybyłowicz. Ni mapping in Berkheya
coddii by Micro-PIXE and NEXAFS.
1. J Mesjasz-Przybyłowicz, W Przybyłowicz. Final
report on the progress of Research Contract No.
13263 entitled “Quantitative studies of cells and
tissues by nuclear microprobe techniques”.
Conference on Quasi-free scattering with
Radioactive Ion Beams, ECT, Trento, Italy, 7-14
April 2008
Joint Symposium of the 14th International
Symposium on Iron Nutrition and Interactions in
Plants and Annual Meeting of HarvestPlus-China
2008 (14th ISINIP) Beijing, China, 11-16 October
2008.
1. A A Cowley. Overview of (p,2p) reactions – what
did we learn?
IAEA
Technical
Meeting
on
in-situ
characterization of materials, Vienna, 19 – 23
May 2008
1. D Urbanski, N Sandal, E Orłowska, J Stougaard,
E Ø Jensen, W J Przybyłowicz, J MesjaszPrzybyłowicz, M A Klein, M A Grusak, C
Cvitanich. Differential iron distribution in seeds
of two closely related legume species.
1. R T Newman et al. In-situ gamma-ray mapping
of primordial and anthropogenic radionuclides in
South African soils - two case studies.
The Technical Meeting (TM) on Special
Configurations and New Applications of
Microanalytical Techniques Based on Nuclear
Spectrometry organized by the IAEA, Vienna, 2024 October 2008.
Nuclear Structure 2008 Conference, Michigan
State University, USA, 3 – 6 June 2008
1. J Mesjasz-Przybyłowicz, W Przybyłowicz. MicroPIXE applied in plant sciences - current status
and perspectives.
2. E O Lieder et al. DSAM Lifetime studies for 134
Nd with AFRODITE.
1. E A Lawrie et al. Possible chirality in the doublyodd 198Tl nucleus.
3. S M Mullins et al. Selective massive transfer via
degrees of incomplete fusion.
35th Annual Conference of the SouthAfrican
Association of Botanists (SAAB), Stellenbosch
University 19-22 January 2009
International Conference on Radioecology and
Environmental Radioactivity, Bergen, Norway,
15 – 20 June 2008
1. J Mesjasz-Przybyłowicz, A D Barnabas, W
Przybyłowicz. Comparison of ultrastructure,
histochemistry and Ni distribution in leaves of Nihyperaccumulating and non-hyperaccumulating
genotypes of Senecio coronatus.
1. I N Hlatshwayo et al. In-situ gamma-ray
mapping of environmental radioactivity at
iThemba LABS and associated risk assessment.
170
Appendices
43rd Zakopane Conference on Nuclear Physics,
Zakopane, Poland, September 1 – 7, 2008
2. S Schroeder, S Rhoda. Radiotherapy with Fast
Neutrons.
1. P L Masiteng et al. Possible chiral bands in the
doubly-odd 194Tl nucleus.
3. D Commins, S Schroeder, F Vernimmen, D
Jones, S de Canha, J Symons, S Fredericks.
Proton Therapy for Meningiomas.
4. S Fredericks. Update of the clinical programme
at iThemba LABS.
International Nuclear Target Development
Society Conference “Target and Stripper foils
technologies for high intensity beams”, France,
15 – 19 September 2008
1st Romanian Society of Hadrontherapy
Workshop, Predeal, Romania, 27 February1 March 2009.
1. N Y Kheswa et al. Manufacturing of calcium,
lithium and molybdenum targets for use in
nuclear physics experiments.
1. C Stannard, F Vernimmen, D Jones, E de
Kock, E Mills, V Levin, S Fredericks, J Hille, A
Hunter. Salivary gland tumours treated with
fast neutron therapy at iThemba LABS, Faure,
South Africa.
International Symposium on In-situ Nuclear
Metrology, Morocco, 13 – 16 October 2008
1. R T Newman et al. Terrestrial in – situ gammaray mapping and applications to viticulture.
2. C Stannard, E Murray, L van Wijk, M Maurel, P
Kraus, F Vernimmen, S Fredericks, S de
Canha. Advanced breast cancer, uterine
sarcoma, irresectable neck nodes and maxillary
sinus tumours treated with neutron therapy.
11th International Conference on Muon Spin
Rotation, Relaxation, & Resonance, Tsukuba,
Japan, 21-25 July 2008.
3. F Vernimmen, Z Mohamed, J Slabbert, J
Wilson. Long-term results of stereotactic
proton beam radiotherapy for acoustic
neuromas.
1. M Madhuku, D Gxawu, I Z Machi, S H Connell, J
M Keartland, S F J Cox and P J C King.
Thermal ionisation of bond-centred muonium in
diamond?
4. F Vernimmen, J Slabbert. The alpha/beta ratio
for proton therapy.
Third South African Conference on Photonic
Materials, Mabula, March 2009.
14th National Congress of the SA Society of
Clinical & Radiation Oncology/ SA Society of
Medical Oncology, Cape Town, South Africa, 1922 February 2009.
1. G O Amolo, J D Comins, R M Erasmus, and T E
Derry. Studies of Defects in Photonic Materials.
1. M Loubser, J Symons, C Trauernicht, S de
Canha, J Parkes, F Vernimmen. A Carbon
Fiber Marker Carrier coupled to a Vacuum Bite
Block for use in Proton Beam Stereotactic
Radiosurgery.
PTCOG 47, Jacksonville USA, 19-24 May 2008
1. J Symons, N Muller, E de Kock, D Maartens, R
van Rooyen, C Trauernicht, M Loubser. The
Search for Higher Precision: Improvements in
the Patient Positioning System for Proton
Therapy at iThemba LABS.
2. S Fredericks, F Vernimmen, L Wessels. Cyst
Formation following Proton Stereotactic
radiotherapy for Arteriovenous Malformations: a
case report.
2. S Rhoda, J Slabbert, T Sebeela, D Jones, J
Symons. Repair of cellular damage in the
plateau region and distal edge of a 200 MeV
clinical proton beam.
3. F Vernimmen. 15 years of proton radiosurgery
experience at iThemba LABS: long-term results
for AVMs, meningiomas, and acoustic
neuromas.
15th ISRRT World Congress, Durban, 24-27 April
2008
1. S Rhoda, J Slabbert, T Sebeela, D Jones, J
Symons. Repair of cellular damage in the
plateau region and distal edge of a 200 MeV
clinical proton beam.
171
Appendices
Workshop on the Monte Carlo Radiation
Transport Code, MCNP, and its Deployment on
Parallel-Architecture Supercomputers at the
CHPC, Cape Town, South Africa, 6 - 7 November
2008.
2. L August, J P Slabbert, A Vral, J Symons.
Variations in the Radiosensitivity of Tlymphocytes of different individuals to a
therapeutic neutron beam.
1. M Swanepoel. Medical Monte Carlo
Simulations.
52nd Academic Day of the University of
Stellenbosch – 13-14 August 2008:
1. W L Solomon, K A Meehan, J P Slabbert and N
E Crompton, D Gihwala. Leucocyte Apoptosis
in Response to Neutron and X-ray Radiation.
Pattern Recognition Association of SA Annual
Congress 2008.
1. J Carstens, N Muller. Fast calculation of digitally
reconstructed radiographs using light fields.
2. J P Slabbert, T T Sebeela, A M Serafin, F J
Vernimmen. The RBE of Different Prostate
Cancer cell Types to high Energy Neutrons.
49th SAAPMB Congress, UFS, Bloemfontein, 2426 March 2009.
48th Annual South African Association of
Physics in Medicine and Biology (SAAPMB)
Congress, Durban, 4-6 June 2008:
1. M Swanepoel, E de Kock. A new range
controlling system for the iThemba LABS
proton therapy nozzle.
1. J P Slabbert, T T Sebeela, A M Serafin.
Potential for Therapeutic Gain treating Prostate
Cancer with high Energy Neutrons.
2. M Swanepoel. Monte Carlo simulations of
some physical aspects of the doses delivered
during experiments to measure the axial
distribution of RBE in proton spread-out Bragg
peaks.
2. W Solomon, K Meehan, J P Slabbert, N A
Crompton, D Gihwala. Leukocyte Apoptosis in
response to Neutron and X-ray Radiation.
3. T Khotle et al. Quality assurance of a 1.5T MRI
scanner at Universitas Hospital using an ACR
MRI phantom.
3. J M Akudugu, J P Slabbert, J Symons. The
Role of Mitochondria-Mediated Apoptosis in the
radiation Response of Prostate.
4. T Khotle et al. Optimization of exposure factors
and image quality for a computed radiography
system.
Nuclear Medical Defence Conference, Munich
11-12 February 2009:
5. C Trauernicht. Determination of the primary
dose component in a 6 MV photon beam using
a small attenuator.
6.
7.
1. P Willems, L August, J Slabbert, H Romm, U
Oestreicher, H Thierens and A Vral. Automated
micronucleus (MN) scoring for population triage
in case of large radiation events.
L August, J P Slabbert, A Vral, J Symons.
Micronuclei formations in T-lymphocytes of
different Individuals following exposure to
Cobalt-60 gamma-rays and high energy
neutrons.
South African Society for Clinical Radiation
Oncology (SASCRO / SASMO) 19 - 22 February
2009, CTICC, Cape Town:
A Baeyens, R Swanson, J P Slabbert, P
Willem, A Vral. The development of a pancentromeric probe used in assessing cellular
damage from low doses of ionizing radiation.
1. J P Slabbert, T T Sebeela, A M Serafin,
F Vernimmen. Variations in the Radiosensitivity
of Different Prostate Cancer Cell lines follow
Treatment with High Energy X-rays and
Neutrons.
36th Annual Meeting of the European Radiation
Research Society (ESRB), Tours, France
1-4 September 2008.
2. W Solomon, K Meehan, N E A Crompton, J P
Slabbert. The Leukocyte Apoptosis Assay:
Standard Curve Study Of A Healthy Western
Cape Population.
1. L August, P Willems, H Thierens, J P Slabbert
and A Vral. Automated micronucleus (MN)
scoring for population triage in case of large
radiation accidents.
172
Appendices
Netherlands Radiobiology Society (NVRB)
Noordwijkerhout, Netherlands 2-3 April 2009:
Tandem Targets for a Vertical Beam Target
Station.
1. V Vandersickel, M Mancini, J P Slabbert, E
Marras, H Thierens, G Perletti and A Vral. The
radiosensitizing effect of Ku70/80 knockdown in
MCF10A cells irradiated with low-LET X-rays
and high-LET radiotherapy neutrons.
Consultants' Meeting on High-precision betaintensity measurements and evaluations for
specific PET radioisotopes, Vienna, Austria, 3 –
5 September 2008
1. G F Steyn, A brief look at selected positron
emitting radionuclides produced at iThemba
LABS.
6th International Conference of Isotopes, Seoul,
Korea, 11-16 May 2008
1. N P van der Meulen, T N van der Walt,
C M Perrang and H G Raubenheimer. The
production of 88Y in the proton bombardment of
natSr.
2. T N van der Walt, N P van der Meulen,
H G Raubenheimer. The production of 133Ba by
a proton-induced reaction on Cs.
13th Biennial Congress of South African Society
of Nuclear Medicine, Windhoek, Namibia, 21-25
August 2008
1. C Naidoo, Overview of iThemba LABS
Radionuclide Production Facilities.
2. C Naidoo, D M Prince, R de Wee, G Sedres,
D D T Rossouw, E Hlatshwayo. Preparation
and characterisation of iThemba LABS
68Ge/68Ga generator.
American Nuclear Society 2008 Annual Meeting,
Anaheim, California, 8-12 June 2008
1. C Naidoo, G F Steyn, Expansion of
Radionuclide Production Facilities of iThemba
LABS
9th Asia Oceania Congress of Nuclear Medicine
and Biology, New Delhi, India, 31 October –
4 November 2008
1. C Naidoo, Characterisation of iThemba LABS
68Ge/68Ga generator.
12th International Workshop on Targetry and
Targetry Chemistry, Seattle, Washington, USA,
21 - 24 July 2008
1. C Vermeulen, G F Steyn, E Isaacs, S DeWindt,
D Saal, H P Burger, C van Rooyen, F C de
Beer, H Knox and J Isobe, Development of
173
4.4
Appendices
Colloquia and Talks
9. C A Pineda-Vargas. Construction and
installation of End-Station for Ion Beam Analysis
for the 1.7 MeV Tandem accelereator at the
Centre for Energy and Research Development
at Ile-Ife, Nigeria, Material Research Group
Users Meeting, iThemba LABS, 30 May 2008.
Accelerator Group
1. J L Conradie: An overview of the iThemba
LABS facility and recent developments.
Laboratorie Du Cyclotron, Nice, France, 27 June
2008.
10. C A Pineda-Vargas. Development of a beam line
for high energy p,X reactions for excitation of the
K-shell of heavy nuclei at iThemba LABS,
Material Research Group Users Meeting,
iThemba LABS, 30 May 2008.
2. J L Conradie: The current status and new
developments of the accelerator facilities at
iThemba LABS. 20-Year Cyclotron Celebration,
iThemba LABS, 26 November 2008.
11. J B Kana Kana. Writing a peer reviewed
publication for the first time, Materials Research
Department and the University of the Western
Cape, 16 October 2008.
3. J L Conradie:
The status and future
development of accelerator facilities at iThemba
LABS. Centre de Recherche Nucléaire d’Alger,
Algeria, February 2009.
12. C Masina. Annealing effects on Pt-coating
morphology, Materials Research Department
and the University of Zululand, 22 October 2008.
13. B Zulu. Characterization of Pt-V single and
multilayered structures, Materials Research
Department and the University of Zululand.
1. B Diop Ngom. W doped-ZnO Nanocoating by
Pulsed Laser Deposition (PLD), Materials
Research Department and the University of the
Western Cape, 5 March 2008.
14. D Smeets. Instantaneous analysis of real-time
RBS using Neural Networks, Catholic University
of Leuven, Belgium, 7 December 2008.
2. C Mtshali. C60 based nano-structures by
molecular recognition and self-assembly,
Materials Research Department and the
University of Zululand, 12 March 2008.
15. H Ammi. The use of indirect transmission
techniques for stopping and struggling
measurements in polymeric film, COMENA,
Algeria, 30 January 2009.
3. M Msimanga. Progress in the development of a
TOF - E spectrometer for applications in HI-ERD
thin
film analysis,
Materials
Research
Department and the University of Cape Town,
19 March 2008.
16. L Gurbous. Photoluminescence, Basics and its
application in rare earth doped systems,
COMENA, Algeria, 30 January 2009.
17. S Mammeri. Sputtering of Bismuth thin films
induced by argon ion beam in the KeV region,
COMENA, Algeria, 30 January 2009.
4. J Jacobson. IBA Techniques in Archaeometry,
McGregor Musium, Kimberly, 26 March 2008.
5. A Cavaleiro. Basic research interest in the SEGCEMUC, 8 April 2008.
18. J Demeulemeester. The influence of additive
elements on the growth of Ni-silicide thin films
studied in-situ, Catholic University of Leuven,
Belgium, 04 March 2009.
6. T Polcar. How to improve the tribological
performance of TMD coatings by the addition of
Carbon, University of Coimbra, Portugal, 08
April 2008.
7. G Favaro. CSM Indentation Testers for Ultra
Nano, Nano and Micro Materials, University of
Coimbra, Portugal, 11 April 2008.
1. J I W Watterson. Gamma-ray Spectroscopy in
Pure and Applied Research. University of the
Witwatersrand and iThemba LABS (Gauteng),
15 July 2008.
8. I Mabuda. The determination of boron using
11B(p,
)8Be nuclear reaction, Materials
Research Department and the University of the
Western Cape, 16 April 2008.
174
Appendices
1. A Chougule. Past, present and Future trends in
Radiobiological Modelling. 16 April 2008.
2. W Solomon. Leukocyte Apoptosis in response
to neutron and X-ray radiation. 7 May 2008.
3. J Gueulette. The RBE of the Clinical Proton
Beam in the very Distal Part of a SOBP. First
results using the special radiosurgery jig. 3
November 2008.
4. V Vandersickel and M Mancini. Lentivirusmediated RNA Interference of Ku70 to Enhance
Radiosensitivity of Human Mammary Epithelial
Cells. 24 November 2008.
175
Appendices
4.5 Post Graduate Training
Degrees Awarded
5. G H Mhlongo. Synthesis and characterization of
nano-structured meso-porous nano-TiO2 by self
evaporation synthesis.
6. K Mbela. The geometry effect and vortex
pinning in high-Tc superconductors, University
of KwaZulu-Natal.
7. C Durrheim. Photometry and characteristics of
tubular fluorescent lamps, University of
KwaZulu-Natal.
MSc
1. L Mkhonza: Evaluation of MicroShield Build-Up
Factors and their Limits of Applicability, NorthWest University, May 2008.
Physics Group
2. N Mlambo, Actibacterial activity testing during
different growth stages of acacia robusta
subspecies clavigera, University of Zululand,
May 2009.
MSc
1. T D Singo. Search for non-yrast states in
University of Cape Town, June 2008.
PhD
1. D Mavunda: Evaluation of radiation detector
systems for mammography X-ray units,
University of the Witwatersrand, December
2008.
160Yb.
2. J P Mira. Production of Li, Be and B nuclei in the
interaction of 12C at incident energies of 200 and
400 MeV. University of the Western Cape,
September 2008.
2. M
M
Dalton:
Baryon
Resonance
Electroproduction at High Momentum Transfer,
University of the Witwatersrand, December
2008.
3. T E Madiba. Directional correlation from oriented
states and linear polarization measurements of
gamma rays from 190 Tl. University of the
Western Cape, September 2008.
3. S R Naidoo: Carbon Overgrowths and Ion Beam
Modification Studies of FCC Crystals by Ion
Implantation, University of the Witwatersrand,
April 2008.
Medical Radiation
MSc
1. J Carstens: Fast generation of digitally
reconstructed radiographs for use in 2D – 3D
image registration. 2008
BSc (Honours)
1. S M Mashego. The association of hydrocarbons
and mineralization in the South Reef at
Doornkop Section, Witwatersrand Basin, South
Africa. University of the Witwatersrand.
MSc
1. E Seane: Radiobiology of neutrons and
protons, Cape Peninsula University of
Technology.
MSc
1. I Mabuda: Determination of boron by 11B
(p, )8Be nuclear reaction, University of the
Western Cape.
2. N. Mongwaketsi. Micro-PIXE study of arbuscular
mycorrhiza influence on elemental uptake by
Berkheya coddii, University of North West.
Postgraduate Students
exoskeleton role in metal elimination in an
insect, Epilachna cf nylanderi, University of
North West.
Medical Radiation
4. P Sotobe Sibiya. Synthesis and Characterization
of nanostructured diamond like carbon by dual
beam pulsed laser ablation-pulsed gas feedings.
J Mbewe
MSc
J Carstens
C Trauernicht
176
Appendices
PhD
11. T Makgato, Interactions of accelerated charged
ions with diamond surfaces, University of the
Witwatersrand.
M A Herbert
B M van Wyk
12. F N Shangase, Environmental isotopes and
evaluation of bio-markers for pollution in
Mozambique tilapia (oreochromis mossambicus)
at Lake Mzingazi, University of Zululand.
BSc (Honours)
13. E Aradi, Heavy-ion modification of soft
hexagonal boron nitride to ultra-hard cubic boron
nitride by ion implantation, University of the
Witwatersrand.
1. M N Xaba, Geohydrological investigation of
Ixapa Town: Towards identifying viable options
of water supply, University of KwaZulu-Natal.
2. K Gravele't-Blondin, The thermal springs of
northern KwaZulu-Natal, University of KwaZuluNatal.
14. M C S Mutheiwana, The assessment of the
causes of high nitrate in ground water in
Bochum District, Limpopo Province, University
of the Witwatersrand.
3. T Mophatlane, Hydrogeological setting of the
Tufa deposit in the Cradle of Humankind, South
Africa, University of the Witwatersrand.
15. T Rossouw, Geochemical characterization of
basement aquifers within the Limpopo Province,
South Africa, University of Pretoria.
MSc
16. M Holland, Groundwater resource directed
measures in Karst terrains with emphasis on
groundwater recharge in the Cradle of
Humankind near Krugersdorp, South Africa,
University of Pretoria.
1. T Sibiya, Radiation shielding design, verification
and dose distribution calculations for industrial
and insect irradiator facilities, University of the
Witwatersrand.
2. C O Kureba, Energy calibration of the 6 MV EN
Tandem accelerator of iThemba LABS
(Gauteng) and measurement of 9Be + 9Be
Scattering, University of the Witwatersrand.
PhD
1. D Gxawu, Possible shallow dopant complex
states in diamond, University of the
Witwatersrand.
3. M Jingo, Characteristics and use of a highresolution ∆E-E gas ionisation detector for
nuclear particle identification, University of the
Witwatersrand.
2. P T Jili, Positron annihilation study of defects in
super-ionic conductors, University of the
Witwatersrand.
4. K G Sekonya, Characterisation of ambient
atmospheric aerosols by using Accelerator
based techniques, University of the
Witwatersrand.
3. M Butler, Towards a Management model based
on Geohydrology, Isotope hydrology and
Hydrochemistry, for the Karoo Acquifers at
Taaibosch, Limpopo Province, University of the
Witwatersrand.
5. M J Raphotle, Modelling of the KAERI 200 MW
pebble bed reactor core, North-West University.
4. E Nshingabigwi, Cross-section transmission
electron microscopy of radiation damage in
diamond, University of the Witwatersrand.
6. W Mampe, The application of nuclear physics
processes for diamond detection within
kimberlite, North-West University.
5. R Machaka, Sliding friction and wear properties
of ion implanted ultra-hard boron-based
materials (provisional title), University of the
Witwatersrand.
7. S M Phoku, The Mineral-PET rock sorter: A
study of the (,n) activation process, North-West
University.
6. A Kozakiewicz, Ion irradiation effects on the
formation of nanoparticle colloids in crystals,
University of the Witwatersrand.
8. W Sibande, Monte Carlo Simulations of nuclear
processes in a high temperature gas cooled
reactor, North-West University.
7. K Jakata, Surface Brillouin scattering at high
temperatures, University of the Witwatersrand.
9. K Buthelezi, Design of a negative ion injection
system for the 6 MV EN Tandem accelerator at
iThemba LABS (Gauteng), North-West
University.
8. E Riddell, Proposal for Isotope Tracer analysis
for the Craigieburn-Manalana Research
Catchment, Limpopo Province, University of
KwaZulu-Natal.
10. I Mayida, University of the Witwatersrand.
177
Appendices
9. V Kongo, Application of Tracer Techniques in
Identifying Runoff Generation Processes in the
Headwaters of the Thukela Basin, University of
KwaZulu-Natal.
nano-TiO2 by self evaporation synthesis.
15. A Haziiot. WO3 for smart windows, INPG,
France.
16. M Urdampilleta. Characterization of TiO2 nanorods, INPG, France.
10. H Saeze, Delineation of deep groundwater flow
regime in the Table Mountain Group, University
of Western Cape.
17. G Kalonga. Characterization and Optimization
of OPV Cells based on P3HT:PCBM Blend,
University of Zambia.
18. A Abiona. Dynamic expansion of Sm1-x NdxNiO
laser ablation plume in oxygen gas, University of
Bab-Ezzoua.
MSc
1. N Shozi. The effects of (H) proton irradiations on
graphene, University of Zululand.
19. A Pajor. Effects of nickel on reproductive activity
of the house cricket, Acheta domesticus
(Orthoptera), University of Silesia, Poland.
2. P Mbuyisa. The effects of photon irradiation on
graphene, University of Zululand.
20. R Wilsdorf. The
seasonal changes in
concentration and distribution of calcium on
cellular level in apple fruit tissue, University of
Stellenbosch.
3. M Nzimande. Radiation induced phase transition
on platinum-based coatings, University of
Zululand.
4. M Cele. Synthesis and physical properties of
nano-structured VOx by sol-gel processing,
University of Zululand.
PhD
1. C L Ndlangamandla. The design of advanced
metal oxide of Iron oxide nanomaterials, thin
films coating for production of hydrogen gas and
its storage devices, University of Zululand.
5. B Zulu. Phase transformation in platinumvanadium single and multilayer structures,
University of Zululand.
2. M Msimanga. Development of a Heavy IonElastic Recoil Detection (HI-ERD) system for
applications in thin film analysis, University of
Cape Town
6. M Modise. Application of X-ray microanalysis to
study the influence of heavy metals on cellular
processes in selected insects, University of
North West.
3. P Sibuyi. Study of the behavior of TRISO coated
fuel particles & thermal Induced interfacial
diffusion Phenomena in PBMR, University of the
Western Cape.
7. M Masina. Annealing effects on morphology of
Pt-Al coatings, University of Zululand.
8. S S Nkosi. Effect of stress on properties of VO2
thin films, University of Zululand.
4. B T Sone. Nano-scale WO3 for Hydrogen
Sensing, University of the Western Cape.
9. Z M Khumalo. Photonics and gas sensing
properties of ZnO nanorods, University of
Zululand.
10. I
5. T P Sechogela. Synthesis and characterization
of VO2 implanted in ZnO by ion implantation.
Mabuda.
Determination of boron by
nuclear reaction, University of the
Western Cape.
6. K Cloete. Effect of a soil yeast, Cryptococcus
laurentii, on growth and nutrition of Agathosma
betulina, University of Stellenbosch
11B(p,)8Be
exoskeleton role in metal elimination in an
insect, Epilachna cf nylanderi, University of
North West.
7. J B Kana Kana. Vanadium dioxide
nanostructured based plasmonics, University of
the Western Cape.
8. B Ngom Diop. Infrared Active Sm1-xNdxNi03
Based Nano-Switchings for High Power Lasers,
University of the Western Cape.
12. N Mongwaketsi. Micro-PIXE study of arbuscular
mycorrhiza influence on elemental uptake by
Berkheya coddii, University of North West.
9. S Khamlich. Nano-Structured Cr2O3 and Optoelectronic applications, Tshwane University of
Technology.
13. P S Sibiya. Synthesis and Characterization of
nanostructured diamond like carbon by dual
beam pulsed laser ablation-pulsed gas feedings.
14. G Hlengiwe Mhlongo. Synthesis and
characterization of nano-structured meso-porous
178
Appendices
10. M Makgaler. Raman Investigations of radiation
induced effects in carbon and silicon carbide
nano-structures, University of North West.
8. S Mohlalisi. Implementation of a customized
ALICE high-level trigger monitoring tool.
University of Cape Town.
11. M Mongoaketsi. Porphyrin nano-rods for light
harvesting systems, University of Stellenbosch
9. J Ndayishimiye. A study of anomalous large
angle scattering of alpha particles. University of
Stellenbosch.
12. I Mabuda. Synthesis of graphene and the effect
of different types of irradiations and study the
chemical properties after exposed to various
radiations, University of Pretoria.
10. J A Swartz. A feasibility study of the use of the
K600 magnetic spectrometer to create neutron
deficient nuclei on the proton drip line. University
of Stellenbosch.
13. K Michalczyk. University of Silesia, Poland
11. J Mabiala. Cross section and analyzing power
distributions in the 12C(p,p)8Be reaction at an
incident energy of 100 MeV. University of
Stellenbosch.
14. P Koosaletse-Meswela. University of Botswana,
Gaborone, Botswana
15. D Drozdz-Gaj. Biomarkers of exposure to heavy
metals and a pesticide (merthiocarb) in selected
organs of terrestrial snails, University of Silesia,
Poland
PhD
1. N Mlwilo. Radiometric characterization of soil,
16. T Sawczyn. University of Silesia, Poland
2. S S Ntshangase. Development and applic-ation
of a recoil detector to study levels in 195-197Po
nuclei, University of Cape Town.
17. G Wojtczak. Jagiellonian University, Krakow,
Poland
18. I Jerzykowska. Jagiellonian University, Krakow,
Poland
3. S A Talha. Uses of radon in water resource
management, University of the Western Cape.
19. S Kanu. Studies of nodule formation and N2
fixation in the tribe Psoraleae, Tshwane
University of Technology
4. I Usman. Fine structure of the isoscalar GQR for
the low mass region 12 < A < 40, University of
the Witwatersrand.
20. M Zamxaka. School of Molecular and Cell
Biology, University of the Witwatersrand
5. M A Stankiewicz. Nuclear structure and reaction
dynamics with AFRODITE and DIAMANT,
Physics Group
6. T T Ibrahim. Studies of clustering phenomena in
nuclei, University of Stellenbosch.
MSc
1. T D Singo. Search for non-yrast states in
7. P L Masiteng. Gamma spectroscopy of oblate
nuclei in A=190 mass region, University of the
Western Cape.
160Yb.
2. J P Mira. Production of Li, Be and B nuclei in the
interaction of 12C at incident energies of 200 and
400 MeV. University of the Western Cape.
8. O Shirinda. Calculating chirality in nuclei.
3. T E Madiba. Directional correlation from oriented
states and linear polarization measurements of
gamma rays from 190 Tl. University of the
Western Cape.
Radiation Biophysics
Postgraduate project
1. B Adam. Chemical dosimetry measurements
and radiation dose calculations for a high energy
Co-60 source at ARC-Infruitec, Sudan AEC,
African Institute of Mathematical Sciences
4. B Adam. Monte Carlo simulation of a collimated
fast neutron beam. University of Cape Town.
5. S Bvumbi. DCO and polarization measurements
in 152Gd. University of the Western Cape.
BSc (Hons) [Honours in Applied Radiation
Science and Technology
6. J P Blanckenberg. Monte Carlo simulation of
geoneutrino
detection.
University
of
Stellenbosch.
1. I Bapela. Radiometry of water from iThemba
LABS dams, North West University.
7. M Segal. Development of a direction-sensitive
antineutrino detector. University of Cape Town.
179
Appendices
MSc / MTech / MMed.
1. Z Jalali. DNA labelling for the assessment of
cellular kinetics in different cancer cell types,
2. R Swanson. Use of molecular markers for
microscopic detection of centromeric regions of
chromosomes, University of the Witwatersrand
3. W Solomon. Flow cytometric and microscopic
analysis of radiation-induced apoptosis in Tlymphocytes, Cape Peninsula University of
Technology.
4. D Narinesingh. Use of Neutrons in Treatment of
Prostate Cancer University of Stellenbosch.
MTech
1. C Perrang: Separation of 88Y from 88Zr and Nb
target material, Cape Peninsula University of
Technology.
2. M van Rhyn: The possible separation of
radioactive contaminants from waste water,
Cape Peninsula University of Technology.
3. S G Dolley: Radiochemical Aspects to resolve a
problem in the determination of the cross section
68Zn(p,xn)64Cu Cape Peninsula University of
Technology.
4. L Taleli: Radiosynthesis of various radioiodinated pyrimidine nucleoside derivatives and
determining their uptakes into cells, Cape
Peninsula University of Technology.
PhD
1. C Vermeulen: Development and modelling of
bombardment facilities at iThemba LABS,
University of Stellenbosch.
2. S Mutsamwira: Separation of some elements by
ion exchange chromatography using a
synthesised ion exchange resin, Cape Peninsula
University of Technology.
180
Appendices
4.6 Users and Collaborators
A Lomax
E Pedroni
International Users and Collaborators
University Center of Medical Technology
(UZMT), Ruhr-Universität Bochum, Germany
R B Heimann
Institute for Nuclear Research (ATOMKI),
Debrecen, Hungary
Z Kormàny
J Panavics
M Posa
G Berek
J Gál
G Kalinka
A Krasznahorkay
J Molnár
B M Nyakó
J Timár
L Zolnai
F Szelecsényi
Z Kovács
Catholic University of Leuven, Leuven, Belgium
A Vantomme
J Demeulemister
D Smeets
Technical University of Clausthal, ClausthalZellerfeld, Germany
R Labusch
Museum of Natural History, Berlin, Germany
U Reimold
Technical University of Münich, Germany
G Dollinger
A Bergmaier
University of Debrecen, Institute of Informatics,
Hungary
K Juhász
University of Silesia, Katowice, Poland
P Migula
M Augustyniak
M Nakonieczny
M Tarnawska
J Juchimiuk
A Babczyńska
A Kafel
T Sawczyn
D Drozdz-Gaj
K Michalczyk
A Pajor
E Głowacka
J Klag
M Rost-Roszkowska
I Poprawa
Forschungszentrum Jülich GmbH, Jülich,
Germany
J Dietrich
F Goldenbaum
W Gast
H Machner
S Qaim
I Spahn
Hahn-Meitner Institute (HMI), Berlin, Germany:
A Denker
International Atomic Energy Agency (IAEA),
Vienna, Austria
N Dytlewski
Polish Academy of Science, Warsaw, Poland
A Wisniewski
A Kortyka
Joint Institute for Nuclear Research (JINR),
Dubna, Russia
O Meshkov
A Efremov
S Bogomolov
S Yakovenko
A Ogloblin
S Shishkin
Laboratori Nazionali di Legnaro, Legnaro, Italy
M Poggi
Jagiellonian University, Krakow, Poland
M Michalik
I Jerzykowska
K Turnau
P Ryszka
G Wojtczak
G Tylko
E Pyza
Paul Scherrer Institute (PSI), Villigen,
Switzerland
J Grillenberger
D Goetz
Jožef Stefan Institute, Ljubljana, Slovenia
J Simčič
P Pelicon
M Budnar
181
Appendices
A Likar
E Lindbo Hansen
M Lipoglavšek
T Petrovič
M Vencelj
T Vidmar
Molecular Biology Institute, University of
Aarhus, Aarhus, Denmark
C Cvitanich
A Jurkiewicz
J Stougaard
E Østergaard Jensen
S Dam
D Urbanski
E Orłowska
N Sandal
University of Ljubljana, Ljubljana, Slovenia
M Regvar
K Vogel-Mikuš
P Pongrac
University of Oslo, Department of Chemistry,
Norway
G Wibetoe
Fysika Institutionen, Lunds Tekniska Högskola,
Lund, Sweden
K Malmquist
J Pallon
P Kristiansson
M Elfman
C Nilsson
B Jonsson
Dipartimento di Scienze Ambientali 'G Sarfatti',
Università degli Studi di Siena, Italy
A Chiarucci
Lund Institute of Technology, Lund, Sweden
B G Carlsson
I Ragnarsson
National Synchrotron Light Source, Brookhaven
National Laboratory, New York, USA
K Evans-Lutterodt
National Institute of Material Science (NIMS),
Tsukuba, Japan
L Vyssieres
Synchrotron SOLEIL, France
J P Itié
P Dumas
V Briois
J Frédéric
Y Ibraheem
James Madison University, USA
B Augustine
National Institute for Agricultural Research
(INRA) INRA-BIA, Nantes, France
F Guillon
Department of Pediatrics, Baylor College of
Medicine USDA-ARS Children's Nutrition
Research Center, Houston, TX, USA
M A Klein
M A Grusak
University of Vienna, Department of Geology,
Vienna, Austria
C Koeberl
Department of Physics, Clark-Atlanta University,
USA
A Msezane
Laboratoire Sols et Environnement INPLENSAIA/INRA Vandoeuvre-lès-Nancy, France
G Echevarria
T Sterckeman
S Raous
Plant Biology Division, The Samuel Roberts
Noble Foundation Inc, Ardmore, Oklahoma,
USA
A J Valentine
Laboratoire Environnement Et Mineralurgie,
CNRS-Nancy Université-INPL, Vandoeuvre les
Nancy, France
E Montarges-Pelletier
Advanced Light Source, Lawrence Berkeley
National Laboratory, Berkeley, USA
T Tyliszczak
University of Le Mans, Department of Physics,
France
A Gibaud
Lawrence Berkeley Laboratory, USA
I Y Lee
Department of Biological Sciences, Auburn
University, Auburn, USA
R Boyd
University of Copenhagen, Denmark
S Husted
182
Appendices
University of California, Los Angeles, USA
D Lundberg
Sultan Qaboos University, College of Science,
Oman
K Bouziane
S El Harthi
International Centre for Tropical Agriculture,
Cali, Colombia
M W Blair
C Astudillo
Sudan University of Science & Technology,
Department of Physics, Khartoum, Sudan
M Eisa
The Federal University of Rio de Janeiro, Brazil
M Oliveira
National University of Zambia, Zambia
K Chinyama
Ottawa University, Canada
I Peripichka
National University of Lesotho, Maseru, Lesotho
N Manyala
M Sekota
L Taleli
L Machel
T Mochochoko
Synchrotron Radiation Source (SRS), Surrey,
United Kingdom
A Korsunsky
University of Surrey, Ion Beam Analysis, Surrey,
United Kingdom
C Jeynes
University of Botswana, Gaborone, Botswana
B Abegaz
O Tortolo
M P Setshogo
P Koosaletse-Meswela
University of Cambridge, Department of
Physics, Cavendish Laboratory, United Kingdom
J F Mckenzie
M Pepper
C Smith
G A C Jones
C B Ford
I Farrer
M Kataoka
University of Namibia, Windhoek, Namibia
F Kavishe
Eduardo Mondlane University, Department of
Physics, Maputo, Mozambique
J F Guambe (BM)
University of Taiwan, Department of Physics,
Taiwan
C T Liang
Addis-Ababa University, Department of Physics,
Ethiopia
G Tessema
G Hailu
University of Coimbra, Mechanical Engineering
Department, Portugal
A Cavaleiro
T Polchar
Centre de Development des Technologies
Avancees-Algiers, Algeria
T Kerdja
Centre de Recherche Nucléaire d’Alger, Algeria
N Ait Said
Z Lounis-Mokrani
CSM, Switzerland
G Fabaro
University of Burdan, West Bengal, India
A Chaundhary
Nuclear Research Centre of Draria, Algiers,
Algeria
A Benzaid
C Ammar
Jawaharal Nehru Center for Advanced Scientific
Research, Bangalore, India
C N R Rao
A Govindaraj
University of Cape Coast, Ghana
YS Mensah
Indian Institute of Sciences (IISc), Bangalore,
India
A Gosh
183
Appendices
Center for Energy Research and Development
(CERD), University of Obafemi Awolowo, Iffe,
Nigeria
G Egharevba
G Osinkolu
S O Olabanji
O Akinwunmi
A A Oladipo
F I Ibitoye
E I Obiajunwa
A Fasasi
Federal Office for Radiation Protection (BfS),
Germany
G Stephan
Florida State University, USA
M A Riley
X Wang
GSI, Germany
T Radon
CSNSM, Orsay, France
C Schück
Ch Vieu
Département Physique / Faculté Sciences and
Techniques, Université Cheikh Anta DIOP de
Dakar, Senegal
S Ndiaye
S C Beye
Institut de Physique Nucléaire (IPN), Orsay,
France
M Assié
F Azaiez
D Beaumel
Y Blumenfeld
J P Ebran
S Franchoo
E Khan
C Monrozeau
B Mouginot
A Ramus
J A Scarpaci
I Stefan
University of Yaounde, Department of Physics,
Cameroon
J M Ndjaka
A F Ioffe Physico-Technical Institute RAS, St
Petersburg, Russia
A Efimov
A A Pasternak
Australian
Australia
P Davidson
P Nieminen
A Wilson
National
University,
Canberra,
INFN, Italy
A Szostak
Bubble Technology Industries, Canada
K Garrow
Institut de Recherches Subatomique, France
G Duchêne
CERN, Switzerland
F Cerutti
A Ferrari
A Mairani
MEDUSA Explorations BV, The Netherlands
R Koomans
J Limburg
Michigan State University, USA
B A Brown
Central Michigan University, USA
M Horoi
M.S. University of Baroda, India
K Kumar
S Mukherjee
China Institute of Atomic Energy, China
L H Zhu
Deutsches
Institut
für
Raumfahrtmedizin, Germany
T Berger
G Reitz
Luft-
Niels Bohr Institute, Denmark
G Sletten
und
National Centre for Health and Environment
(GSF), Germany
E Schmid
EARTH Foundation, The Netherlands
R J de Meijer
184
Appendices
Peking University, China
H Hua
J Meng
S Y Wang
S Q Zhang
D Mengoni
D Petrache
C Petrache
University of Cologne, Germany
C Fransen
K O Zell
Physikalisch-Technische Bundesanstalt,
Braunschweig, Germany
V Dangendorf
M Luszik-Bhadra
R Nolte
S Röttger
B Wiegel
University of Edinburgh, United Kingdom
A Murphy
University of Groningen, Kernfysisch Versneller
Instituut, The Netherlands
H Wörtche
RCNP, Japan
G P A Berg
K Fujita
K Hatanaka
M Matsubara
A Tamii
University of Ibadan, Nigeria
I Farai
University of Istanbul, Turkey
B Akkus
N Erduran
I Izgur
Royal Institute of Technology, Stockholm,
Sweden
R Wyss
University of Liverpool, United Kingdom
A J Boston
H Boston
M Dimmock
D Joss
P J Nolan
E S Paul
S V Rigby
C Unsworth
Royal Military College of Canada, Canada
L Bennet
M Boudreau
B Lewis
STFC Daresbury Laboratory, United Kingdom
J Ollier
N Rowley
J Simpson
University of Madrid, Spain
N Schunk
Technische Universität Darmstadt, Germany
O Burda
Y Kalmykov
M Kuhar
A Lenhardt
I Poltoratska
V Yu Ponomarev
L Popescu
N Pietralla
A Richter
A Shevchenko
P von Neumann-Cosel
J Wambach
University of Milan, Italy
R Bassini
P Colleoni
E Gadioli
E Gadioli Erba
A Guglielmetti
Insubria University, Milan, Italy:
P Perletti
M Mancini
University of Notre Dame, USA
G P A Berg
S O‟Brien
M Wiescher
University of Birmingham, United Kingdom
M Freer
University of Bordeaux, France
J N Scheurer
University of Camerino, Italy
M Fantuzi
185
Appendices
University of Osaka, Japan
T Adachi
Y Fujita
J Martinez
B de Coster
V Grégoir
A Wambersie
University of Oxford, United Kingdom
B Buck
*P Hodgson
A C Merchant
University of Ghent, Ghent, Belgium
A Vral
P Willems
B Thierens
L de Ridder
V Vandersickel
University of Pavia, Italy
A Mairani
University of Sofia, Bulgaria
D Balabanski
A Minkova
Bundesamt für Strahlenschutz und Gesundheit,
Oberschleissheim, Germany
H Romm
U Oestreicher
University of York, United Kingdom
S P Fox
B R Fulton
D G Jenkins
F Johnson-Theasby
P Joshi
A Laird
R Wadsworth
Department of Earth
University, Netherlands
M Drury
Sciences,
Instituto Technologico Nuclear, Portugal
A Belchior
Cornerstone University, Michigan, USA
N Crompton
Sunnybrook Health Sciences Centre, Toronto,
Canada
J P Pignol
R Reilly
Utrecht
Ghana Atomic Energy Commission, Ghana
D Achel
University of Western Ontario, Canada
D Moser
Korea Atomic Energy Research Institute,
Jeongup-si, Daejeon, South Korea
J S Chai
S D Yang
Ludwig Maximilians University, Department of
Earth and Environmental Sciences, Geophysics
Section, Munich, Germany
S Gilder
Los Alamos National Laboratory, USA
M Nortier
Institut de Physique du Globe de Paris,
Laboratoire de Paleomagnetisme, Paris, France
J Badro
M Le Goff
A Galdeano
Erasmus Hospital, Rotterdam, Holland
W A P Breeman
Deutsches Krebsforschungszentrum,
Heidelberg, Germany
A Höss
W Schlegel
Department of Earth, Atmospheric, and
Planetary Sciences, Massachusetts Institute of
Technology, Cambridge, Massachusetts, USA
L Carporzen
Medical College of Jaipur, India
A Chougule
Midwest Proton-Therapy Facility, Bloomington
IN, USA
D F Nichiporov
UAE University, Abu Dahbi, United Arab
Emirates
K Meehan
Pro-Cure Treatment Centres Inc., Bloomington
IN, USA
A N Schreuder
Catholic University Louvain, Brussels, Belgium
J Gueulette
186
Appendices
Istituto Nazionale di Fisica Nucleare - Laboratori
Nazionali del Sud, Catania, Italy
G Cuttone
G A P Cirrone
F di Rosa
D Heiss
G C Hillhouse
N M Jacobs
J A Stander
J J van Zyl
S Wyngaardt
Department of Geology
A Rozendaal
South African Users and Collaborators
Cape Peninsula University of Technology:
B Mokaleng
B Wyrley-Birch
M von Aulock
C le Roux
Department of Medical Imaging and Clinical
Oncology
A Ellmann
F Vernimmen
A Serafin
W Groenewald
Department of Biomedical Technology
W Solomons
D Gihwala
E Truter
J Esterhuizen
S Khan
M Zerabruk
Z Jalali
Department of Occupational Medicine
B de Villiers
Department of Microbiology
M Kwaadsteniet
Department of Physiology
S Hatting
R Smith
Faculty of Applied Science
T N van der Walt
M R van Heerden
C Liu
Department of Plant Pathology
A Viljoen
L Rose
Durban University of Technology
D Gxawu
Department of Chemistry and Polimer Science
H G Raubenheimer
P Mallon
Rhodes University
N Torto
Tygerberg Hospital: Department of Radiation
Oncology
F J Vernimmen
J K Harris
G Georgiev
L Dupper
P C van Eeden
Stellenbosch University
E P Jacobs
M W Bredenkamp
P Swart
S Govender
U Buttner
L Lorenzen
J Symons
R Maleri
A Botha
K Cloete
G Stevens
E Lötze
R Wilsdorf
K I Theron
Tygerberg Hospital:
S Rubow
J W Warwick
J Pelser
Tshwane University of Technology
F Dakora
S Kanu
Department of Applied Mathematics
B Herbst
University of Cape Town
T Egan
K de Villiers
M Cerf
H Hawkins
Department of Physics
J Bezuidenhout
187
Appendices
M Cramer
A Rodgers
C Lang
R Knutsen
M de Wit
Department of Geography, Environmental
Management and Energy Studies
H Annegarn
Department Of Physics
S H Connell
M S Allie
D G Aschman
D Britton
F D Brooks
A Buffler
J Cleymans
C Comrie
R W Fearick
I Govender
M Harting
M Herbert
S Jones
M R Nchodu
H E Seals
T Volkwyn
S Walton
Y Zhang
University of Kwazulu Natal
L L Jarvis
D S McLachlan
University of North West
Centre of Applied Radiation Science and
Technology
E N Mongwakets
M Modise
M Makgale
University of Pretoria
Department of Pharmacology
C Medlin
Department of Radiation Oncology
J A G Wilson
Institute of Infectious Diseases & Molecular
Medicine
M Madziva
J Visser
Pretoria Academic Hospital
M Sathekge
University of the Free State
M Ntwaeborwa
D Ben
R Luyt
Department of Medical Physics
E Hering
J K Hough
Department of Medical Physics
A van Aswegen
H du Raan
Department of Clinical Pathology
J J Hille
R Abratt
E A Murray
C E Stannard
A L van Wijk
K Marszalek
J J P Maurel
P Kraus
A Hunter
A Hendricks
L Goedhals
University of the Western Cape
D Knoesen
R Majoe
K Streib
M Tchokonte
S Halindintwali
J N Mugo
G Balfour
P Ndugu
A Valentine
S Naidoo
U Chikte
M Williams
J Mars
S Naidoo
L Petrik
Department of Astronomy
M Inggs
Department of Electrical Engineering and
Instrumentation
J Tapson
University of Johannesburg
188
Appendices
R Lindsay
D G Roux
I Schroeder
J F Sharpey-Schafer
University of Zululand
T Jili
Department of Physics and Engineering
J Dlamini
O M Ndwandwe
O Nemraoui
S Govender
Department of Earth Sciences
U Saeze
Department of Medical Bioscience
M de Kock
L August
Z Jalali
Africon
M Levin
Agricultural Research Council
Infruitec - Nietvoorbij
P Sange
T Blomefield
University of the Witwatersrand
S Webb
T Mophatlane
K Sekonya
S Piketh
J Sagalas
C Straker
M Zamxaka
I M Weiersbye
L D Aswal
Arnelia Farms, Hopefield
H Hettasch
Citrus Research International
H Hofmeyr
M Hofmeyr
S Groenewald
S Steyl
Department of Human Genetics
P Willem
Constantiaberg Mediclinic
R Mellvill
D van der Merwe
Council for Geoscience, Pretoria
F Roelofse
E Berdermann
J Carter
H Fujita
F Makayi
E Sideras-Haddad
J Larkin
T Derry
M Naidoo
D Comins
Council for Scientific and Industrial Research
(CSIR), Pretoria
C Arendse
S Sinha Ray
T Hillie
S Thema
CSIR
Environmentek
C Colvin
P Hobbs
A Maherry
G Tredoux
School of Geophysics
G R J Cooper
Department of Biomedical Engineering
R Mlambo
CSIR
Meraka Institute
B Becker
Johannesburg General Hospital: Department of
Radiation Oncology
B Donde
CSIR
National Metrology Laboratory – Rosebank
B Simpson
F van Wyngaardt
University of Venda
I Matamba
K P Mutshena
189
Appendices
CSIR
National Laser Center
N Cingo
G Katumba
M Moodley
Steffen, Robertson & Kirsten Consulting
N Sutria
D Duthe
Sun Space and Information Systems (Pty) Ltd.
E Jansen
K B Mathapo
N Steenkamp
Department of Health
S Olivier
E Snyman
Eskom
P Frampton
Water Geosciences Consulting
M Holland
R Titus
Integrated Seismic Systems (ISS) International,
Stellenbosch
R van Rooyen
Unassigned
C V Levin
E Mills
Kimberly Museum, Kimberley, South Africa
L Jacobson
Koeberg
M Alard
Little Company of Mary Hospital
J A G Wilson
Mintek
Advanced Materials Division, Randburg
E van der Linden
R Suss
R Tshikhudo
National Nuclear Regulator
W J Speelman
T Tselane,
Nuclear Energy Corporation of South Africa
(Necsa), Pretoria
J N P Segonyane
C Franklyn
F de Beer
J Nell
M Andreoli
G K Mabala
K P Maphoto
Red Cross Children’s Hospital, Cape Town
M Mann
Simonsig Wine Estate
F Malan
South African National Accreditation System
N Tayler
190
Appendices
4.7 Staff List (as on 31 March 2009)
Radio-Frequency
J van Niekerk - Division Head
D April
G Price
H du Plessis
W Duckitt
Directorate
ZZ Vilakazi - Director
JJ Lawrie - Interim Deputy Director
E Hudson – Personal Assistant
Physics
RT Newman - Interim Group Head
SV Förtsch
EA Lawrie
SM Mullins
F Gonglach
JP Mira
FD Smit
RA Bark
R Neveling
EZ Buthelezi
NY Kheswa
SM Perez - Research Associate
IN Hlatshawyo
AA Cowley - Research Associate
P Datta - Post-Doc
PL Masiteng
JF Sharpey-Schafer – Honorary Research Associate
Diagnostic & Vacuum
P Rohwer - Division Head
C Antonie
L Anthony
R McAlister
G Pfeiffer
L Ashworth
L Heinkelein
D de Villiers
Hospital Services
P Fördelmann - Division Head
L Faviers
C Diba
A Lawrence
E Booysen
J de Morney
M Karels
M Bond
S Daniels (Stephanie) - Supervisor: Kitchen
F Fredericks - Supervisor: Houskeeping
J Fuller
S Daniels (Sanna)
L Arendorff
E Knoop
B Michaels
L Nigrini
J Petro
A Rhoda
S Rose
A Steyn
M Turner
E van Zyl
E Mraqisa
Accelerator
JL Conradie - Group Head
D Fourie – Deputy Group Head
P van Schalkwyk – Deputy Group Head
A Raman – Secretary
J Delsink
A Botha
R Thomae
G de Villiers
S Ntshangse
K Springhorn
S Marsh
C Doyle
Cyclotron Operation
M Sakildien - Division Head
B Greyling
S Eloff
N Khumalo
E van Oordt
K Fortuin
C Williams
E Sauls
M Dire
H Anderson
Finance
V Spannenberg - Division Head
C Saaiman
D Smith
F Wallace
A Tyhali
L Sabsana
N Moshenyane
191
Appendices
Electronics & Information Technology
J Pilcher - Group Head
L Serutla - Deputy Group Head
S Watts – Secretary
N Rabe
Radiation Protection
D McGee - Division Head
T Modisane
NE Mzuzu
WJ Fredericks
J Otto
S Sam
Software Engineering
M Hogan - Division Head
C Oliva
C Pieters
C Ellis
S Murray
MA Crombie
A Sook
L Pool
P Cronje
General Administration
Y Manjoo - Business Manager
N Oliver – Secretary
L Davids
R Hendricks
G Christians
E Theunissen
Electronic Engineering (R&D)
N Stodart - Division Head
H Mostert
P Petev
S Stefanov
J van der Merwe
P Jones
H Gargan
Stores
I Antonie – Supervisor
A Ntunzi
Safety, Health & Environment
F Daniels - Division Head
J Fredericks
B du Preez
A Lombard
M Lots
L Sidukwana
ED Knoop
J Aron
S Klaaste
D Theunissen
E Sono
S Silwanyane
EN Matoshwa
S Magwa
Z Diba
T Tocke
J Mncube
NM Marks
MR Mentyisi
Library & Information Systems
N Haasbroek - Division Head
W Zaal
A Sauls
Information Technology Support
I Kohler - Division Head
J Krijt
A Phillips
M Robertson
M van der Ventel
Electronic Engineering (I & M)
S du Toit - Division Head
C Lussi
M Klop
J Solomons
O Smith
C Baartman
H Klink
P Davids
R Pylman
T Boloyi
N Klaasen
P Sheodass
iThemba LABS Gauteng
M Madhuku – Interim Group Head
G Badenhorst – Interim Deputy Group Head
D Monyamane – Secretary
R Chirwa
R Hart
A Kwelilanga
M Labuschagne
M Mthembu
O Pekar
N Makhathini
P Chuma
K Radebe
Radiation Biophysics
J Slabbert - Group Head
A Baeyens – Post-Doc
192
Appendices
NV Radebe
KF Balzun
N Hadebe
N Mahlare
H Shipalana
J Watterson
TT Matsibiso
GK Sekoyane
M Rebak
T Mashego
SM Selinyane
M Williams
N Ndyalvane
A du Plessis
M Adams
W Kearns
J Augustine
P Paulsen - Supervisor: Workshop
C Alexander
D Payn – Apprentice
K Kunana
M Davids
Environmental Isotopes Laboratory
M Butler - Division Head
M Mabitsela
O Malinga
Site Services
P Gardiner - Division Head
G September – Supervisor
J Pietersen (Johnny)
J Petersen (Kosie)
P Visagie
R Adams (Rasdien)
PJ Jacobs
DJ Arendse
J Carelse
V Nkhalashe
P Naidoo
I Joseph
R Adams (Riyad)
R Hendricks
L Swartz
Z Nogqala
M Isaacs
J Makhasi
E Kanow
LL Ntuma
C Muller
N Xhelo - Apprentice
N Mngqibsa – Apprentice
Materials Research
R Nemutudi - Group Head
L Cuba – Secretary
J Crafford
J Mesjasz-Przybylowicz
M Maaza
M Topic
A Barnabas - Research Associate
CA Pineda-Vargas
T Doyle - Research Associate
M Nkosi
M Msimanga
R Bucher
P Sechogela
R Minnis-Ndimba
A Nechaev – Post-Doc
W Przybylowicz
K Bharuth-Ram – Honorary Research Associate
Medical Radiation
J Nieto-Camero - Interim Group Head
(& Division Head, Operations & Treatment Division)
E van Ster – Secretary
Human Resources
N Africa - Division Head
M Plaatjies
M van der Meulen
B Msiza
T Ramosie
Treatment Planning & Development
E de Kock - Division Head
M Swanepoel
NL Muller
B Martin
C van Tubbergh
C Callaghan
Science & Technology Awareness
G Arendse - Division Head
A Yaga
R Linden
Technical Support Services
Mechanical Engineering
D Wyngaard - Division Head
L Adams
J van der Walt
L Bizwaphi
193
Appendices
Operations & Treatment
S Schroeder – Supervisor Treatment
J Symons – Supervisor Operations
M Loubser
PC du Plessis
P Bonnett
T Khotle
Clinical Research
S de Canha - Division Head
D Commin – Supervisor
S Fredericks
Radionuclide Production
C Naidoo - Group Head
D Opperman – Secretary
V Jackson
Physics & Targetry
G Steyn - Division Head
G Swarts
E Isaacs
PS Louw
S Losper
C Vermeulen
S de Windt
D Saal
Radiochemistry
N Rossouw - Division Head
N van der Meulen
Radiopharmacy
D Prince - Division Head
CR Davids
R Anthony
X Mncedane
G Sedres
S Dolley
A Pakati
M van Rhyn
CM Perrang
S Buwa
S Dyushu
194

March 2009 - iThemba LABS

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