Vol. 25 No. 2

Transcription

Vol. 25 No. 2

Nuclear Physics News
International
Volume 25, Issue 2
April–June 2015
FEATURING:
Issue No. 100!
10619127(2015)25(2)
COVER 2
Ad to come
Nuclear Physics News
Volume 25/No. 2
Nuclear Physics News is published on behalf of the Nuclear Physics European Collaboration Committee (NuPECC), an Expert Committee of the
European Science Foundation, with colleagues from Europe, America, and Asia.
Editor: Gabriele-Elisabeth Körner
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Maria José Garcia Borge, Madrid (Chair) Eugenio Nappi, Bari
Rick Casten, Yale
Klaus Peters, Darmstadt and EPS/NPB
Jens Dilling, Vancouver
Hermann Rothard, Caen
Ari Jokinen, Jyväskylä
Hideyuki Sakai, Tokyo
Yu-Gang Ma, Shanghai
James Symons, Berkeley
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Vol. 25, No. 2, 2015, Nuclear Physics News1
Nuclear
Physics
News
Volume 25/No. 2
Contents
Note from the Editor
Is 100NPN Doubly Magic?
by Gabriele-Elisabeth Körner...................................................................................................................... 3
Editorial
40 Years: Decay or “Half-Life” Crisis?
by Martin Hynes and Jean-Claude Worms................................................................................................... 4
Feature Article
The Road to Precision: Extraction of the Specific Shear Viscosity of the Quark-Gluon Plasma
by Chun Shen and Ulrich Heinz................................................................................................................... 6
Facilities and Methods
Spin-Aligned Radioactive Isotope Beams via Two-Step Fragmentation Reaction
by Hideki Ueno and Yuichi Ichikawa............................................................................................................ 12
Exploring the Most Exotic Nuclei with MINOS at the RIBF
by Alexandre Obertelli and Tomohiro Uesaka............................................................................................. 17
The HADES Pion Beam Facility
by Piotr Salabura, Joachim Stroth, and Laura Fabbietti............................................................................. 22
Impact and Applications
Toward Applications of b-NMR Spectroscopy in Chemistry and Biochemistry
by Monika Stachura, Alexander Gottberg, Magdalena Kowalska, Karl Johnston,
and Lars Hemmingsen.................................................................................................................................. 25
Meeting Reports
STORI’14: 9th International Conference on Nuclear Physics at Storage Rings
by Peter Egelhof, Yuri Litvinov, and Markus Steck...................................................................................... 30
FAIR 2014: A Vibrant EPS Conference on the Future of Nuclear and Hadron Science in Europe
by Klaus Peters............................................................................................................................................. 32
ARIS 2014
by Takaharu Otsuka...................................................................................................................................... 35
News and Views
European Strategy for Particle Physics
by Tatsuya Nakada........................................................................................................................................ 38
In Memoriam
In Memoriam: George C. Morrison (1930–2015)
by Martin Freer............................................................................................................................................ 40
Calendar.................................................................................................................................. Inside back cover
A magic eye—probing the time-like structure of excited nucleons by detecting virtual photons. Photograph of the HADES spectrometer looking towards the detection plane of the RICH detector (see article on page ???)
UPDATE
2
Nuclear Physics News, Vol. 25, No. 2, 2015
note from the editor
Is 100NPN Doubly Magic?
At the time of my thesis, “Towards
was a dream,* but even further
away from reality would have been
the thought that many years later I
would reach 100NPN, the 100th issue
of Nuclear Physics News.
The first issue, Vol. 1 No. 1, appeared in September 1990, only two
years after the founding of NuPECC
(Nuclear Physics European Collaboration Committee), the driving force behind the project. It took four years and
a dinner at Argonne with Dave Hendry
from the Department of Energy to get
the United States on board; Canada
and Japan followed a year later, and
since 2012 China also takes part in the
adventure.
This is a good occasion to thank all
those who have contributed to the success, first of all:
100Sn”
*The dream came true a few years later, at
the same place—GSI Darmstadt—realised by
a team from the Physikdepartment E12 of the
Technische Universität München …J (and a bit
later also at GANIL).
• the chairs of the Editorial Board,
starting with the founding chair
Adriaan van der Woude over
Sydney Galès, George Morrison, Juha Äystö, Muhsin Harakeh, Mark Huyse, Paul-Henri
Heenen, to now Maria José García Borge,
• the correspondents who pointed
out interesting developments in
their countries,
• and last, but not least, the many
enthusiastic colleagues who delighted the readers with their
editorials, laboratory portraits,
feature articles, contributions to
facilities and methods, impact
and applications, and news and
views, but who also sometimes
had to sadden us with an obituary of a highly esteemed member
of the community.
The calendar of events became a
sought-after item, and the special issues on nuclear physics activities
in Japan, the World Year of Physics
2005, as well as the FAIR and J-PARC
projects were quite successful.
All this would not have been possible without the help of so many dedicated colleagues and friends to whom
my special thanks go at this time!
Now the answer to the question in
the heading: yes, I think that 100NPN
is doubly magic; against some predictions, it is still around, and some
people even seem to like it. Therefore
I am optimistic that we will make it to
132NPN and even beyond!
Acknowledgment
The views expressed here do not
represent the views and policies of
NuPECC except where explicitly
identified.
Gabriele-Elisabeth Körner
NuPECC Scientific Secretary;
Editor, Nuclear Physics News
Filler
editorial
40 Years: Decay or “Half-Life” Crisis?
The European Science Foundation
(ESF)—and its collaborators, several
Expert Boards and Committees that
are nearly as venerable—turned 40
last year. The celebration was a lively
one, highlighting an eventful past. The
event applauded the achievement of
thousands of researchers over these
four decades and the great benefits
of European collaboration in science.
NuPECC’s chair Angela Bracco attended the event, along with chairs of
Expert Boards and Committees and
Scientific Review Groups.
The ESF was originally set up to
act as a coordinating body for Europe’s main research funding and
performing organizations. But as the
landscape evolved, so did ESF’s role
in supporting scientific endeavors.
At a time of economic crisis Member Organizations (MOs) wishing to
downsize their international payments
considered the future of the association and came close in May 2011 to
summarily dissolving the organization. The European heads of Research
Councils and ESF members decided
to separately establish Science Europe
in Brussels with the mission to act as
Europe’s science policy body, but not
to take over nor reproduce the crossborder funding instruments and tools
of ESF, which are now disappearing
from the landscape.
This translated to a strong drain of
ESF financial and human resources—
a reduction of Euro 15.4 million in
MO contributions for 2015 compared
to 2010, and dramatically reduced
staff numbers. In accordance with the
members’ decisions, ESF is therefore
winding down its traditional network-
ing activities to reach completion by
the end of 2015. Despite all this ESF
has demonstrated that it has the experience and agility to face challenges
and turn them into opportunities. Indeed, at the 2014 Assembly, MOs
agreed to allow business planning to
proceed with a go/no go deadline of
end May 2015. If the business planning is accepted at that time, the existing association will not be dissolved
and will continue, with or without a
change of name, on the understanding
that its activities do not compete with
those of Science Europe.
With this new approach ESF will
work as a science service provider to
public institutions and private research
foundations and thereby support the
European Research Area (ERA) by
concentrating on activities designed
to support and sustain the funding and
conduct of scientific research across
Europe, and helping research funding
organizations carry out their decisionmaking processes. The essential core
of such evidence-based support to decision making will be Peer Review,
Evaluation, expert hosting, and Project Management.
Peer Review and Evaluation activities will be at the core of daily business in the ESF successor. We have
recently completed an information
memorandum describing the future
activities; it will be distributed to all
interested stakeholders. ESF has carried out project work for many MOs
as well as other not-for-profit organizations. The work with the AXA Research Fund (ARF) has proved particularly fruitful in delivering effective
views of scientific excellence and in
expanding the capabilities of both organizations. Similarly, evaluation services spring from a long-term dialogue
with MOs on appropriate structures
and methodologies. In 2012, ESF conducted a detailed review of scientific
evaluation practices across European
research organizations and issued an
MO Forum report entitled Evaluation
in Research and Research Funding
Organisations: European Practices.
Other recent projects include organizational evaluation reports on the Research Council of Lithuania and the
Hungarian Scientific Research Fund
(OTKA). Building on a committed
college of highly regarded and experienced reviewers ESF is able to provide outstanding scientific peer review
support to institutes or organizations
implementing competitive calls across
all scientific domains. ESF is therefore positioned as a benchmark peer
review and evaluation provider at the
European and international level.
ESF can call on unrivaled experience managing both individual
research projects and larger programmes at the international level.
ESF has managed a considerable
number of scientific projects funded
by the European Commission and
MOs, supporting and collaborating
with national institutions. Another
example of providing key support
for European decision making is the
Mapping of the European Research
Infrastructure Landscape (MERIL)
project, which is an online database
of research infrastructures across all
fields of research in Europe. The resulting Web portal gives an easily
searchable list of openly accessible
The views expressed here do not represent the views and policies of NuPECC except where explicitly identified.
4
editorial
research infrastructures in Europe that
are of more than national relevance
across all scientific domains (http://
portal.meril.eu/converis-esf/public
web/startpage?lang=1).
But even more importantly for NuPECC and other similar expert bodies,
for many years ESF has hosted Expert
Boards and Committees (NuPECC,
CRAF, EMB, EPB, ESSC, MatSEEC)
with strong experience of supporting and influencing ministerial and
other high-level fora at the European
and international level. These boards
and committees have the visibility,
expertise and authority to wield influence with major decision makers,
funding agencies, and governments.
The Expert Boards and Committees
develop the strategic approach to their
domains in close collaboration with
national authorities in member nations or European-wide agencies and
research entities. They are composed
of high-level independent researchers
or research managers, nominated by
their stakeholders to provide targeted
expert advice in areas of science, policy, infrastructure, environment, and
society in Europe.
As the result of their 2011 statutory
review ESF MOs and Science Europe
have accepted that “… all Boards and
Committees provide scientific services in the European or even global
framework that are indispensable for
Europe’s scientific landscape” (ESF
2011, Statutory Review of the Expert
Boards and Committees, ESF Strasbourg, ISBN 978-2-918428-53-4).
While Science Europe decided that
there was potential benefit to collaborating with these interdisciplinary
groups, they felt however that they
would not be the appropriate platform
from which to operate. The maintenance of this platform and collaboration is therefore of central importance
and the ESF Governance has agreed
that, should the viability check be
positive in May 2015, this “successor
organization” would be the optimal
platform for the Expert Boards and
Committees. With one exception (the
European Polar Board), all the other
Boards and Committee have come to
a similar conclusion.
The November 2014 Assembly adopted amendments to the ESF statute
that facilitate new types of membership in the organization. It is probable
that we can build a relationship with
a key technology provider as a member. Big data approaches and effective
application of social media, as well as
streamlined internal procedures will
all be important to the future of all
stakeholders.
It is our strong belief therefore
that we hold the key to our future development: science services, project
management, and expert hosting. For
nuclear physicists, stability is boring.
We have an opportunity here and now
to rebuild a dynamic and evolving
structure, able to support Europe in its
research ambitions.
ORCID
Jean-Claude Worms
org/?????????????????
http://orcid.
Martin Hynes
CEO, European Science Foundation
Jean-Claude Worms
Head Science Support,
European Science Foundation
Filler
feature article
The Road to Precision: Extraction of the Speciﬁc
Shear Viscosity of the Quark-Gluon Plasma
Chun Shen AnD ulriCh heinz
Department of Physics, The Ohio State University, Columbus, OH 43210-1117, USA
Overview
ForafewfleetingmomentsaftertheBigBangtheuniversewasfilledwithanastonishinglyhotanddensesoup
knownastheQuark-GluonPlasma(QGP),aprecursorto
the matter we observe today that consisted of elementary
particles. Although this Quark-Gluon Plasma also containedleptonsandweakgaugebosons,itstransportproperties were dominated by the strong interaction between
quarks and gluons. Utilizing the most powerful particle
accelerators,physicistsnowconducthead-oncollisionsbetweenheavyions,suchasgoldorleadnuclei,torecreate
conditionsthatexistedatthebirthoftheuniverse.Themost
strikingdiscoveryinrelativisticheavy-ioncollisionsisthat
thehotanddensemattercreatedduringthecollisionsbehaveslikeanalmostperfect(inviscid)liquid,meaningthat
itcanbecharacterizedbyaverysmallshearviscosity(η)
toentropydensity(s)ratio(or,“specificshearviscosity”)
[1–4].Itturnsoutthattheη/sfortheQGPissmallerthan
1006502
that of any known substance, including that of superfluid
liquidhelium.InFigure1,weillustrateschematicallythe
1 ;
specificshearviscosityη/snormalizedby 4
kB ,theminimumboundinalargeclassoftheorieswithinfinitelystrong
coupling[5],forfourdifferenttypesoffluids.TheQGPat
hightemperatureexhibitsthesmallestvalueofη/sofany
4 kB s
fluidsoccurringinnature.
"1 e i ˆ1
"n e inˆn
1006502
1 ;
4 kB
Sincethediscoveryaroundtheturnofthemillenniumof
theQGPanditssurprisinglyperfectfluidity,stronginterest
hasemergedinboththeoreticalandexperimentalworkto
constrainthetransportpropertiesoftheQGPinrelativistic
heavy-ioncollisions.Thespecificshearviscositycharacterizesoneofthemostimportanttransportpropertiesofthe
QGP.Itisatpresentimpossibletocomputethistransport
coefficientwithanysortofprecisionfromfirstprinciples.
Alternatively,theoreticalanalysisoftheexperimentsconductedattheRelativisticHeavy-IonCollider(RHIC)and
the Large Hadron Collider (LHC) offers opportunities to
unravelphenomenologicallythecollectivebehaviorofthe
QGP created at high energies. Importantly, since the fireballs created in these “Little Bangs” are minuscule (V ~
10–42 m3)andcoolalmostinstantly(~5×10−23 s),physicists can only study the QGP through its remnants. This
raises unique experimental and theoretical challenges. To
tracetheinformationofthedetectedstableparticlesback
totheQGPphaseattheearlystagesofthecollisions,inordertoextracttheQGP’sproperties,requiresaquantitative
understandingoftheentireevolutionofaheavyioncollision,fromtheformationandthermalizationoftheQGP
tothedynamicsofthehadronresonancegasintowhichit
eventuallydecays.(Aschematicviewoftheevolutionas
we currently understand it is illustrated in the left panel
ofFigure2).Suchareverseengineeringprocessrequires
goodcontrolofallthemodeluncertainties,inadditionto
R
aconsistentdescriptionofalargevarietyofmeasuredobrdrdr 3 e.r; /e i servables.
and
D R
rdrdr 3 e.r; /
Inthisfeaturedarticlewehighlightthemajorrecentad(1)
R
vancesintheoryandexperimentinconstrainingtheQGP
rdrdr n e.r; /e in
R cshearviscosity.Webeginbyexplainingthemain
.n 2/;
Dspecifi
rdrdr n e.r; /
ideaofhowtomeasureη/sinheavy-ioncollisions.
The QGP Viscometer
R
dN
inp
Dynamics
and
Hadron Elliptic Flow:
dp dyd
eCharged
Figure 1. The fluid imperfection index of various fluids Bulk
p
in‰n
e
D
and
kB R
ArtdN
4 s as a function of temperature. This picture is taken n The State of the
dp dydp
Thesuccessofviscoushydrodynamicsindescribingthe
from Tribble R (chair), Burrows A et al., Implementingthe
(2)
R
2007LongRangePlan, Report to the Nuclear Science Ad- bulkevolutionofrelativisticheavy-ioncollisionsatRHIC
inp
dp dypT dN
e
dp
d
T
p
.pT /
owdatalatercollected
visory Committee, 31 January, 2013. Available atnhttp://
.pT /e in‰n[6]andpredictinganddescribingfl
D R
;
dN
d
R
p
attheLHC[7,8]leadstoanimportantconclusion:atthe
science.energy.gov/np/nsac/reports/.
dypT dpT dp
rdrdr 3 e.r; /e i and
"1 e i ˆ1 D R
rdrdr 3 e.r; /
R
6
Nuclear
Physics
News, Vol. 25,(1)No. 2, 2015
n
in
rdrdr
e.r;
/e
"n e inˆn D R
.n 2/;
1
1
rdrdr n e.r; /
:
(3)
2:5 s QGP
4
4
R
feature article
1006502
1 ;
4 kB
4 kB
s
"1 e
i ˆ1
D
R
rdrdr 3 e.r; /e i R
rdrdr 3 e.r; /
and
(1)
R
1006502
n
in
rdrdr
e.r;
/e
"n e inˆncollisions.
.n 2/;
D R Right:
Figure 2. Left: Illustration of the dynamical evolution of relativistic heavy-ion
The collective
space time
rdrdr n e.r; /
evolution of the collision systems created at the RHIC and the LHC, compared with an ultra-cold fermi gas [9]. The tem1 ;
perature is color coded.
4 kB
macroscopic level, initial anisotropic pressure gradients in
the fireball drive the system to collectively develop a momentum anisotropy, as illustrated in the right panel of Figure 2. This dynamic evolution shares a great deal of similarity with other strongly coupled many-body systems, such as
ultra-cold fermi gases [9]. Inhomogeneities and anisotro1006502
CORREX
pies
in the- initial
density distribution can be characterized
by the spatial eccentricities {εn, Φn} defined by
"1 e
"n e
i ˆ1
inˆn
R
r dr d r 3 e.r; /e i and
D R
r dr d r 3 e.r; /
R
r dr d r n e.r; /e in
.n 2/;
D R
r dr d r ne.r; /
(1)
where r and φ are polar coordinates in the transverse plane
perpendicular to the beam direction. (At top RHIC and
LHC energies, the dynamics along the beam direction is,
to
good approximation,
1006503
- CORREX boost-invariant, i.e., independent
of the longitudinal motion of the reference frame, and
therefore less informative for the present discussion than
the transverse
dynamics.)
Similarly, the azimuthal depenX
p
k Dof the
2I emitted
C1
.1/l m momentum distribution can
dence
particles’
be characterized bymthe anisotropic(1)
flow coefficients vn and
their associated event plane angles Ψn, defined by
hI; m; i; mjk; 0ia.m/
2 D
s
4 kB
s
n e
in‰n
D
R
dN
dp dyd
e inp
p
R
dN
dp dyd
p
(2)
inp
dp dypT dN
e
dpT dp
/
n .pi
/e in‰n Trdrdr
D 3Re.r; /e i dN
;
and
"1 e T ˆ1 D R
d
p
3
dyp
dp
d
T
T
p
rdrdr e.r; /
(1)
R
n
in
rdrdr
e.r;
/e
inˆn
where pT"and
R coordinates in transverse
.n 2/; momenDpolar
n e φp are
n e.r; /
rdrdr
tum space. The conversion
efficiency
from the initial {εn}
1 in the medium
to the final {vn}1 is degraded
by viscosity
:
(3)
2:5 [10]; this is the main
effect
that
opens
the
door to measuring
s QGP
4
4
η/s with anisotropic flow observables.
In particular, the secondRorder anisotropic
flow coeffidp dN p e inp
cient, dubbed the elliptic
of
charged
hadrons
was
in‰n flow v2, dyd
D R
and
ne
dN
first measured in heavy-ion experiments
at
the
CERN
SPS
dp dyd
p
and RHIC. In Figure 3, we compare the RHIC measure(2)
R
inp
ments to results from viscous hydrodynamic
simulations,
in
dp dypT dN
e
dp
d
T
p
in‰n .pT /
;
order to extract
η/s of
theD
QGP.RBy confronting
state-of-then .pT /e
dN
p dypT dpT dp
art phenomenological modeling d
with
precise experimental
measurements, the specific shear viscosity of the QGP can
be constrained as [10]
R
.p
R
1
1
:
2:5 4
s QGP
4
Vol. 25, No. 2, 2015, Nuclear Physics News
5
I.I C 1/.2I C 3/.2I 1/
X
m
f3m2 I.I C 1/ga.m/
and
(3)
7
feature article
Figure 3. Eccentricity-scaled charged hadron elliptic flow as a function of final charged hadron multiplicity per overlapping area compared to a viscous hydrodynamics + hadron cascade hybrid simulation in Au + Au collisions at top RHIC
energy. The plot is taken from Ref. [10].
AglanceatFigure1showsthateventheupperlimitlies
muchbelowtheminimalspecificshearviscositiesseenobservedinanyotherpreviouslyknownfluid.However,since
thecentralvalueissosmall,theremainingrelativeuncertaintyisstilllarge.Itisdominatedbymodeluncertainties
intheinitialconditions(thetwopanelsinFigure3showthe
samedatacomparedwithtwotypicalinitial-statemodels);
itisirreducibleunlessfurtheranisotropicflowobservables,
inadditiontotheellipticflow,aretakenintoaccount.
Event-by-Event Anisotropic Flow Distributions:
Disentangling the Influence of Viscosity and
Initial State Fluctuations
WithimproveddetectiontechniquesatRHICandnew
dataatthehigherLHCenergies(whereeachcollisioncreatesmorethantwiceasmanyparticlesasatRHIC),higher
order anisotropic flow coefficients of particle momentum
distributionshavenowalsobeenpreciselymeasured[11].
The full anisotropic flow spectrum {vn} provides us with
enoughinformationtodisentangletheextractionofη/s for
theQGPfromthedynamicalconsequencesofthegeometric shape of the initial-state and its quantum fluctuations
thatwereattheheartofthemodeluncertaintyseeninFigure 3 [12, 13].
Figure 4 shows recent results from (3+1)-dimensional
viscous fluid dynamical simulations [14] performed with
thecurrentlymostadvancedinitialstatemodelforheavyion collisions, the IP-Glasma model [15]. The left panel
illustrates that this approach provides a precise and consistentdescriptionofthemeasuredchargedhadronanisotropicflowcoefficients,v2 to v4,with(η/s)QGP = 0.2 [16]
(recentlyrefinedto(η/s)QGP=0.18[17]).Themiddleand
rightpanelsofFigure4showthat,evenmoreimpressively,
the IP-Glasma model initial density distributions, after
viscous hydrodynamic evolution, yield an almost perfect
description of the experimentally unfolded vn probability
distributions[16].Experimentalaccesstothefullspectrum
of vn coefficients and to the probability distributions of
Figure 4. Left: Charged hadrons anisotropic flow vn compared with the state-of-the-art IP-Glasma + viscous hydrodynamic
(MUSIC) simulations for Pb + Pb at 2.76 A TeV. Middle and Right: Event-by-event v2,3 probability distributions compared
with the same model simulations. The plots are taken from Ref. [16].
8
feature article
Figure 5. Time line of precise extraction of the specific shear viscosity of QGP. The plot is taken from the “Hot & Dense
QCD White Paper,” solicited by the NSAC subcommittee on Nuclear Physics Funding in the United States. Available at
http://www.bnl.gov/npp/docs/ Bass_RHI_WP_final.pdf.
theirevent-by-eventfluctuationshaschangedthescopefor
aprecisedeterminationoftheQGPspecificshearviscosity:
aphenomenologicalextractionof(η/s)QGPwitharelative
precision of order 5–10% now appears within reach.The
samedata,aswellasseveraladditionalrecentlyidentified
flowfluctuationandflowcorrelationobservablesthatfocus
morespecificallyonthefluctuatingbehavioroftheflowanglesΨn[18–21]alsopromiseawaytosimultaneouslyconstrainthespectrumoftheinitial-statequantumfluctuations.
Theprocedureinvolvesextensivemodelingcombinedwith
advancedstatisticalanalysistools[22],mirroringmodern
studiesofthecosmicmicrowavebackground[23].
In all, through efforts in the development of sophisticatedphenomenologicalmodelsandimprovementsinthe
precision of the anisotropic flows measurements, the extractionoftheQGPη/shasbecomeincreasinglyaccurate.
Figure5summarizesatimelineoftheimprovementinconstraintsplacedonη/softheQGPoverthepastdecade.We
canseethattheuncertaintyofthevalueoftheQGPη/shas
shrunkdramatically.Theconvergenceisduetoprogresson
boththetheoreticalandexperimentalsides.Atthecurrent
stage, theoretical models and experimental measurements
arebothbeginningtoreachthesensitivitynecessarytoconstraineventhetemperaturedependenceof(η/s)(T)[7,24,
25],aswellasthatofothertransportcoefficients,suchas
thebulkviscosity[26]andvarioussecond-ordertransport
coefficients.
Outlook and Challenges
Whilephenomenologicalmodelingwithhydrodynamics
hasledtoanexcellentdescriptionandtosuccessfulpredictionsofmostsoft( pT<2GeV/c)hadronicobservablesin
relativisticheavy-ioncollisions,therearesome“outliers”
thatthecurrentstate-of-the-arttheoreticalapproacheshave
difficultiesexplaining.
Figure 6. Left: Charged hadrons anisotropic flow vn compared with viscous hydrodynamic simulations for 0–0.2% ultracentral Pb + Pb collisions at 2.76 A TeV [27]. Middle: Direct photon elliptic flow compared with event-by-event viscous
hydrodynamic models [38]. Right: Charged hadrons elliptic flow in peripheral Pb + Pb collisions and central p + Pb
collisions at LHC compared to the model calculations [39].
9
feature article
In the left panel of Figure 6, the CMS collaboration measured charged hadron anisotropic flow vn in 0–0.2% ultracentral Pb + Pb collisions at 2.76 A TeV [27]. The relatively similar size of the measured v2 and v3 coefficients is
a striking feature that challenges current phenomenological
model descriptions [28] (while ε2 and ε3 are predicted to
be similar in these collisions, shear viscous effects should
suppress v3 more strongly than v2). Additionally, in the past
3 years, a surprisingly large direct photon elliptic flow has
been reported by the PHENIX collaboration at RHIC [29,
30] and later confirmed by the ALICE collaboration at the
LHC [31, 32]. All current theoretical models underestimate
the measured photon momentum distributions and elliptic flow by factors of 2 to 4 [33–37] (a typical model/data
comparison is shown in the middle panel of Figure 6). This
major challenge has become known in the field as the “direct photon flow puzzle.” Finally, the right panel of Figure
6 shows that the current state-of-the-art phenomenological
model with IP-Glasma initial conditions [16] fails to provide a consistent description of the measured elliptic (and
triangular, not shown) flow coefficients in p + Pb and Pb +
Pb collisions at the LHC [17]. While this does not necessarily invalidate the hydrodynamic paradigm, it at least shows
that our theoretical understanding of the internal structure
of the proton and of the fireballs it creates when colliding
with a large nucleus is still incomplete.
Resolving these puzzles requires further improvements
of the theoretical model from the description of initial state
fluctuations to more realistic bulk dynamic evolution and
to the detailed reconstruction of the particle correlations in
the final states.
With higher statistics accumulated in the experiments,
the anisotropic flow of rare probes, like high-pT charged
hadrons ( pT > 10 GeV), direct photons, D mesons, J/ψ, and
so on, are now being or will soon be measured to satisfactory precision. Compared to the bulk soft hadrons, the
anisotropies of these rare particles can probe earlier dynamics of relativistic heavy-ion collisions. In principle, they are
more sensitive to the temperature dependence of η/s in the
high temperature region. A combined analysis of these rare
observables with the anisotropic flow of charged hadrons at
a variety of collisions energies will help us to further constrain our theoretical models and improve the precision of
our extraction of the QGP transport coefficients.
Acknowledgments
This work was supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under
Awards No. DE-SC0004286, and (within the framework of
the JET Collaboration) DE-SC0004104.
10
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1039–1044.
Chun Shen
Ulrich Heinz
Filler?
facilities and methods
1006502 - CORREX
R
r dr d r e.r;
/e
Spin-Aligned Radioactive
Isotope
Beams
via
and
" e
D R
1006502 - CORREX
r dr d r e.r; /
Two-Step Fragmentation Reaction
R
3
1
i
i ˆ1
3
"n e
D R
R r dr d 3r ne.r; /i netic quantum
number
natural
r dr m.
dInr ae.r;
/e
R a uniform distri"1 e i ˆ1a(m)
D has
condition,
r dr d r 3 e.r; /
bution, and ρk = R0 (k ≠ 0). However,
when adding
a certain
toin
r drmanipulation
d r n e.r; /e
inˆn
R
"
e
D
n
n
this
population
to make
r dr the
d distribur e.r; /
1006503
- CORREX
tion of a(m) uneven, the value of ρk is
no longer 0. The condition expressed
by ρ1 ≠ 0 (distribution with a primary
X
p
l m polarasymmetry)
the “spin
k D 2I isCcalled
1
.1/
ization”
1006503condition,
- CORREX
mand that expressed
(1)
by ρ2 ≠ 0 (distribution with a second hI; m; i;ismjk;
ary asymmetry)
called0ia.m/
the “spin
alignment”
X Specifically, the
p condition.
k D tensor
2I C 1ρ2 indicating
.1/l m the spin
statistical
m
alignment can be expressed
as
(1)
s
hI; m; i; mjk;
5 0ia.m/
2 D
I.I C 1/.2I C 3/.2I 1/
inˆn
Introduction
Recently the “dispersion-matching
two-step projectile-fragmentation (PF)
method” has been developed as a new
spin manipulation technique for a
quantum system called a radioactive
isotope (RI) beam [1]. This method
obtains an RI beam with a high production yield while producing universally high spin alignment for a large
variety of RIs. A proof-of-principle
experiment was performed at the
RIKEN RIBF facility [2]. By applying this method, it is expected that the
measurement of the nuclear moment
of an unstable nucleus, which was
previously impossible, can be accomplished. In this article, after discussing
the conventional mechanism for producing a spin orientation, the principle
of the new method, demonstration
experiments, evaluations based on the
results
of -these
experiments, and fu1006502
CORREX
ture prospects are described.
Production of Spin
R Orientation
3
i
with "the
i RI
ˆ1 BeamRr dr d r e.r; /e
D
1e
3 e.r; /
We first introducerthe
dr spin
d rorientation of a nucleus.R The definition is in
in
r dr d r n e.r; /e
accordance
For
"n e inˆn with
D theR literature [3].
n
e.r;
/
r dr
dI,rthe
an ensemble of nuclear
spin
distribution of the quantum state with a
magnetic quantum number m is stated
by the statistical tensor ρk of the rank
k (k = 0, 1,..., 2I). The statistical ten1006503
CORREX
sor
ρk can-be
expressed using ClebshGordan coefficients 〈 j1, m1, j2, m2|J,
M 〉:
X
p
k D 2I C 1
.1/l m
m
(1)
where a(m) represents the distribution for a condition with the mag2 D
12
s
5
X
f3m2 I.I C 1/ga.m/
sm
5
(2)
2 D
I.I C 1/.2I C 3/.2I 1/
The spin X
alignment A is defined as
f3mρ22 standardized
I.I C 1/ga.m/
an amount
of
with
m
the maximum
possible value of |ρ2|
2
(2)
(|ρA
). For example, if I  2, when
2|max
and
j2 jmax is localized at m = ±I,
the distribution
(3)
|ρ2| reaches
its(1)
2 maximum and is exX 3m
I.I C 1/
pressed
a.m/
D as
I.2I 1/
.n 2/;
m
2
A
j2 jmax
(3)
X 3m2 I.I C 1/
a.m/
D
I.2I a 1/
b
m T1 D
(4)
0 1
In 1990, it was discovered that
these spin orientations are produced
concomitant to a PF reaction
[4]. It
a b
is known that
T1 this
D reaction can be de(4)
1
scribed well with a0 simple
model in
which the secondary beam nucleus
(fragment) produced in the reaction is
a spectator part obtained by removing
the nucleons involved in the reaction
Nuclear
Physics
I.I C 1/.2I
C 3/.2I
1/ News, Vol. 25, No. 1, 2015
X
m
f3m2 I.I C 1/ga.m/
(2)
(1)
.n 2/;
from the primary beam nucleus (proand and can be approximated to
jectile)
withdraw from(1)
the reaction itself [5].
As a major characteristic of this PF
.n 2/;it can be mentioned that the
reaction,
fragment shows momentum distribution around the momentum p0 corresponding to the projectile velocity, reflecting the total momentum pn of the
participant portion caused by the Fermi
motion. Because the angular momentum LF produced in the fragment after
the reaction becomes a function of the
traveling-direction component of the
beam ( pF//) of the fragment momentum ( pF) (Figure 1), by choosing the
momentum of the fragment after the
reaction, a production of fragments
that have been spin-orientated and the
RI beam can be extracted. However,
it has also been revealed that the spin
orientation is partially or completely
attenuated, when a large nucleon removal is involved in the PF reaction.
This is because the reaction cannot be
simplified as described above in such
cases, and other reaction channels
such as a central collision are opened.
Because primary beams that can be
delivered at a high current are usually
limited to several types of nuclei such
as rare gas elements, spin alignment
can be produced only for their neighboring RIs.
Principle of the DispersionMatching Two-Step ProjectileFragmentation Method
To maximize the spin alignment,
as observed in the aforementioned
mechanism, it is better if the PF reaction is “simple.” Thus, to produce the
target RI beam nucleus AF (particles
are denoted by their mass number in
this section), the “most simple PF re-
Figure 1. Prediction of fragment spin alignment as a function of the outgoing
parallel momentum pF// in the PF reaction. On the bottom, situations for the
outgoing fragment velocity vF < v0 , vF ≈ v0 , and vF > v0 are illustrated, where v0
denotes the projectile velocity. For other notations, see the text.
action” that removes only one nucleon
(proton or neutron), is used. That is,
we use a two-step PF reaction process
in which an intermediate nucleus with
one additional nucleon compared with
the target nucleus (AI (= AF + 1)) is
first prepared from the primary beam
nucleus AP. Next, the target nucleus,
AF, is produced with a one-nucleon
removal reaction. In this way, it is expected that the spin alignment can be
maximized regardless of the nuclide
AF. Although the improvement in the
spin alignment can be expected by
simply conducting the reaction twice,
because it is produced twice, the momentum selection associated with it
must be performed twice. This leads to
a large demerit in the production yield
of the RI beam (Figure 2b). That is, in
a simple two-step PF method, the spin
alignment and production yield trade
off, and both of these cannot be improved concurrently.
An important aspect to note is that
the spin alignment is determined by
the change in the momentum due to
(secondary) the PF reaction that produces the target nucleus AF , and it
does not depend on the momentum
of the intermediate nucleus AI. That
is, even if the PF reaction was used
twice, if the change in the momentum due to the secondary reaction is
directly extracted, the reduction in the
production yield can be minimized. A
key technique to solve this problem is
the momentum dispersion matching
[6, 7]. We have previously mentioned
that when producing a spin alignment
using the PF reaction, a momentum
selection must be made. To select the
momentum, the momentum dispersion depending on the velocity is produced by inserting a dipole magnet.
However, in order to earn the production yield, this momentum dispersion
must be converged again after the
momentum selection. The conditions
of the ion-beam optics related to this
Figure 2. Comparison of three different schemes of spin-aligned RI beams. For
details, see the text.
r dr d r e.r; /e
and
"1 e i ˆ1 D R
r dr d r 3 e.r; /
R
inˆn
"n e
.n 2/;
D R
r dr d r ne.r; /
momentum selection and the achromatic beam transportation after the
1006503 -are
CORREX
selection
called the “dispersionmatching condition.” This condition is
often used in experiments to precisely
X structures using
examinepnuclear level
k D 2I C 1
.1/l m
a nuclear
reaction.
m
(1)
The principal of directly extracting
only thechange
in
the
momentum
due
to the secondary reaction in the dispersion-matching two-step PF method
can be explained as follows (Figure
2c). Introduce
the two-component vecs
tor t(x, p), which expresses
the posi5
2 D
tion
of the beam particle x (horizontal
I.I C 1/.2I C 3/.2I 1/
misalignment from the central orbit)
X p (misalignment from
and momentum
f3m2 I.I C 1/ga.m/
the central value), and examine how
m
this vector is expressed on each focal
(2)
plane. In the first PF reaction from the
primary beam, a secondary beam AI is
produced within a narrow range on the
target. The vector for this beam parti2
cle AI is expressed
as t(x0(AI), p0(AI)) =
A
t(0,
Δp),jwhere
2 jmax ∆p is a difference from
the central momentum
for particle(3)
AI
X 3m2 I.I C 1/
produced
in
the
first
PF
reaction.
Aca.m/
D
1/ optics, the
cording mto theI.2I
ion-beam
transport to the downstream dispersive focal plane can be expressed by
the matrix
a b
T1 D
(4)
0 1
where a is magnification, and b is momentum dispersion. Secondary beam
particle AI on the dispersive focal
plane is expressed by vectors
x1 .AI /
x .A /
bp
D T1 0 I D
p1 .AI /
p0 .AI /
p
(5)
Position the second reaction target on
this dispersive focal plane, and produce the target nucleus AF through
the second PF reaction.
c d Because the
T
D
(6)
position is unchanged
2
0 1 by the reaction, xI(AF) = xI(AI). If the momentum
variation accompanying the second
14 x2.AF /
p2 .AF /
(1)
PF reaction
asδp, the
is defined
mo
x1 .AI / of the beam
x0 .A
after
mentum
particle
AFbp
I/
D T1
D
p1reaction
p0 .ApI /I(AF) = p
.AI /
∆p +
the
becomes
δp. This AF passes through the dipolar
(5)
magnetic field again and is transported
to a focal plane further downstream.
The corresponding transfer matrix is
defined as
x1 .AI / T D xc0 .AdI /
bp
(6)
D2T1 0 1 D
p1 .AI /
p0 .AI /
p
where c is magnification, and d is mo(5)
mentum dispersion. To eliminate the
momentum dispersion and make an
the top
right
achromatic
x2 .AF /focal plane,
x1 .AF /
D
T
2 T T must be 0.
element
inFthe
p2 .A
/ matrix
.A
1 F/
p21
This condition, given
by d = −bc,(7)
is
c d
(6)
T2 D
called the “dispersion-matching
conbcıp
D 0 1
dition.” When the p
dispersion-matchC ıp
ing condition is fulfilled, vectors on
the focal plane can be expressed as
x2 .AF /
x1 .AF /
D
T
2
.t/
"N
.t/
N
24 /
p2 .ADF / 13
p1 .A
F
R.t/
N13 .t/
C
"N
24 .t/
bcıp
D
p C ıp
and position x2 is only dependent on
32 variation
F2
theR.t/
momentum
δp in
the secD
cos 2.!
L t C ˛/
4 C 2 FThis
2
ond PF reaction.
means that the
N13 .t/ "N24.t/
(9)
beamR.t/
particle
(8)
D that produced the same
N13 .t/ Cin"N
24 .t/
momentum variation
the
second PF
reaction connects the focal point at the
same position on the focal plane. The
size of spin alignment is a function of
momentum variation δp in the reaction
32 F2
toR.t/
produce
nucleus
D the targetcos
2.!L t (second
C ˛/
4
2 F2 research); thus, it
PF reaction C
in this
(9)
is possible to only extract component
δp related to the spin orientation out
of the final momentum variations of
AI, ∆p + δp, through a slit on the focal
plane. In this manner, cancellation of
the spin alignment due to the mixing
of different momentum components
can be avoided, and a significant increase in the production yield can be
achieved while maintaining the maximized spin alignment.
Nuclear
x1 .AF / Physics News, Vol. 25, No. 1, 2015
D T2
p1 .AF /
bcıp
D
p C ıp
(7)
(8)
(7)
Experiments with RIBF
A demonstration experiment for
this method was conducted using the
superconducting in-flight RI separator BigRIPS [8] of the RIBF facility
[2]. In this experiment, as shown in
Figure 3, the target nucleus 32Al was
produced from the primary beam of
48Ca through 33Al. In the first reaction
on the F0 focal plane, 33Al was produced through the PF reaction between
the 48Ca beam with a beam energy of
E/A = 345 MeV on a Be target. This Be
thickness was chosen such that the production yield of the secondary beam,
33Al, was maximized. The secondary
reaction was initiated using an aluminum target positioned at the dispersive focal plane F5. Then, the relevant
32Al beam was produced by the onenucleon removal reaction from 33Al.
The Al-target thickness was selected
such that the momentum spread due
to the fluctuation of the reaction position in the depth was as small as that
produced intrinsically in the one-nucleon removal reaction. This isomeric
state was populated at the same time
in the secondary reaction. The finally
obtained 32Al beam, containing the
isomeric state of 32mAl [9], was then
transported to the final focus to satisfy
the dispersion-matching condition.
The spin alignment was measured
by means of the time-differential perturbed angular distribution method
(TDPAD method) [10]. 32mAl stopped
within a stopper crystal placed between two magnet poles and started
a Lamor precession within a static
magnetic field B0. Provided that the
isomeric state has been spin-aligned,
γ rays are emitted with an angular
distribution that is non-isotropic with
respect to the quantization axis; thus,
if the alignment axis rotates owing
to the spin precession, changes in the
strength of the γ ray measured by a Ge
detector fixed in a lab will be synchronized with the precession.
x1 .AI /
x .A /
bp
D T1 0 I D
p1 .AI /
p0 .AI /
p
(5)
x1 .AI /
x0 .AI /
bp
D T1 c d D
p1 .AI / T D
p0 .AI /
p(6)
2
0 1
(5)
Figure 3. Arrangement of BigRIPS RI separator for the production spin-aligned
RI beams.
x .A /
x2 .AF /
D
T2c d1 F
p2 .AFT
p1 .AF /
/ D
(6)
2
The TDPAD
method
evaluates (7)
the in the direction of the beam axis in this
0 1
anisotropy of a γ ray
angular distri- experiment. ωL is the Lamor precesbcıp
bution with a D
function
p CR(t),
ıp and the sion frequency. α represents the initial
spin alignment can be determined phase.
from its amplitude. R(t) is defined as
The isomeric state 32mAl of 32Al
follows:
is known to de-excite through an E2
x1 .AF /
x2 .AF /
D T2
transition as it emits a γ ray with an
p2 .AF /
p1 .AF /
N13 .t/ "N24.t/
energy of 222 keV [11]. We designed
(7)
(8)
R.t/ D
bcıp
N13 .t/ C
"N24 .t/
an R(t) plot according to Eq. (8) for a
D
p C ıp
222-keV γ ray (Figure 4). Using a fitwhere N13(t) and N24(t) are the sum of ting based on Eq. (9), the spin alignthe γ-ray count rate for Ge 1 and Ge ment was determined to be A = 8(1)%.
3 and the sum of the γ-ray count rate
3Ge
2 F2 4, respectively, and
forR.t/
Ge D
2 and
cos 2.!L t C ˛/
N
13 .t/ "N24.t/
4
C
theyR.t/
are positioned
(8)ϵ
D 2 F2diagonally, while
(9)
N13correcting
.t/ C "N24differences
.t/
is the factor for
in the detection efficiency of the detector. Theoretically, R(t) is expressed
as follows:
R.t/ D
Summary and Future Prospects
Owing to the remarkable development of the accelerator in recent years,
the nuclides that can be produced
32 F2
cos 2.!L t C ˛/
4 C 2 F2
(9)
where F2 is the anisotropy parameter
determined by the initial and final state
spins and multipolarity of the γ-ray
emission process. The spin alignment
A appears in ρ2, as defined by Eq. (1).
In addition, the spin alignment axis is
To assess the success and failure of
the dispersion matching—that is, to
confirm that the spin alignment was
not attenuated—the momentum slit
on F5 was narrowed to ±0.5%, and a
measurement was conducted in which
the horizontal position where the secondary reaction occurs was limited. At
this time, the spin alignment was A =
9(2)%, which agrees with the value of
A = 8(1)% in the case where the dispersion matching was used. Thus, it
was confirmed that by satisfying the
condition of the dispersion matching,
an improvement in the production
yield of the target nucleus 32Al could
be achieved while maintaining the
spin alignment. A measurement was
also made where 32Al was directly
produced from 48Ca with the conventional one-step PF method for comparison. This reaction strips 16 nucleons. Because the spin alignment was
low, a significant amplitude for the obtained R(t) was not observed (the spin
alignment was 0.8% or lower for 2σ
confidence). Details of the experiment
are described in Ref. [1].
Figure 4. The R(t) plot derived according to Eq. (8) for de-excitation γ rays from
the isomeric state in 32Al. A solid curve represents the results that were fitted
using Eq. (9).
as an RI beam are expanding twodimensionally on the nuclear chart.
Furthermore, in the RI range with a
large mass number, many long-life
isomeric states have been discovered
in recent experiments [12]. The presently developed new spin-alignment
beam-production method—the dispersion-matching two-step PF method—
provides us an opportunity to study
spin-related observables of far-unstable nuclei. In particular, by combining
this technique with the powerful RI
beam-production capacity of a stateof-the-art accelerator facility such as
RIBF, research into nuclear structures
through nuclear moment over an extensive mass region may see new possibilities. Moreover, inserting the spinoriented RI beam into the substance
can create further new possibilities in
physical properties research that uses
nuclear spin as a probe to extract magnetic impurity or radiation.
Acknowledgments
This research was the result of accelerator experiments conducted at the
RIBF facility. We would like to extend
our sincere appreciation for the accelerator and the beam-time coordination
staff at RIBF. This research was con-
ducted with a total of 26 collaborators
from RIKEN Nishina Center, Tokyo
Institution of Technology, Tokyo
Metropolitan University, Okayama
University, INRNE (Bulgaria), CEA
(France), CSNSM (France), and KU
Leuven (Belgium).
References
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(2012) 918.
2. Y. Yano, Nucl. Instrum. Meth. B 261
(2007) 1009.
3. H. Morinaga and T. Yamazaki, InBeam Gamma-Ray Spectroscopy
(North-Holland, Amsterdam, 1976).
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(1990) 488.
5. J. Hüfner and M.C. Nemes, Phys. Rev.
C 23 (1981) 2538.
6. B.L. Cohen, Rev. Sci. Instrum. 30
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7. H.G. Blosser et al., Nucl. Instrum.
Meth. 91 (1971) 61.
8. T. Kubo, Nucl. Instrum. Meth. B 204
(2003) 97.
9. M. Robinson et al., Phys. Rev. C 53
(1996) R1465.
10. A.J. Freeman and R.E. Watson, Phys.
Rev. Lett. 6 (1961) 343.
11. S. Grévy et al., Nucl. Phys. A 734
(2004) 369.
12. D. Kameda et al., Phys. Rev. C 86
(2012) 054319.
Filler?
16
Hideki Ueno
RIKEN Nishina Center for
Accelerator-Based Science,
Saitama, Japan
Yuichi Ichikawa
RIKEN Nishina Center for
Accelerator-Based Science,
Saitama, Japan
Exploring the Most Exotic Nuclei with MINOS
at the RIBF
Introduction
Rare isotopes, both by their significant neutron-over-proton unbalance or
their weak binding, offer unique features to understand atomic nuclei. The
completion of facilities dedicated to
produce radioactive ion beams worldwide has allowed one to span new regions of the nuclear landscape where
new properties of nuclei, in particular
the evolution of shell structure, can be
investigated. It is now established that
the nuclear shell structure, as unraveled from stable nuclei, is not universal across the entire nuclear chart but
evolves depending on which neutron
and proton orbitals are occupied. Intensive theoretical efforts driven by
new experimental findings have led
to clarification of microscopic mechanisms for such changes and their
predictions are confronted to further
observations. Away from stability, the
shell model picture of a nucleus can
also be subject to significant modifications due to low binding energy
of Fermi nucleons. New phenomena
have been observed in the past decades. The development of weakly
bound neutron halos occurs in light
nuclei at the neutron drip-line, as well
as strong nucleonic correlations under
the form of alpha clustering. Many
quantum phenomena related to rare
isotopes raise fundamental questions
that remain to be solved: Can we reach
a universal description of nuclear
structure? What are the origins of shell
evolution? How do the di-neutron correlations appear in Borromean nuclei?
What are the conditions for clustering
to emerge? What is the role of the underlying structure of nucleons in lowenergy nuclear physics?
The Radioactive Isotope Beam
Factory (RIBF) of RIKEN in Japan
was completed in 2007 and is today
the world’s leading facility in the
production of very exotic nuclei at
intermediate energies. Other newgeneration rare-isotope facilities are
under completion or upgrade in Europe (FAIR, SPIRAL2, SPES, HIEISOLDE), in North America (ARIEL,
FRIB), and Asia (HIAF, BRIF, Raon)
and shall offer multiple attack angles
to the question of nuclear structure.
New experimental devices together
with increasing beam intensities create unprecedented research opportunities and improve our understanding
when combined with state-of-the-art
theories. In the following, we present
the physics program recently undertaken at the RIBF based on hydrogen-induced direct reactions with the
newly developed MINOS device.
Hydrogen-Induced Reactions
Hydrogen-induced reactions have
unique advantages to investigate nuclear structure, as it has been extensively shown in direct kinematics experiments by use of a proton beam on
stable-nucleus targets. The hydrogen
nucleus is the simplest hadronic probe
available as a target. One can foresee
that in the coming decade(s), low-energy transfer and intermediate energy
knockout from an initial A + 1 nucleon
system could be at reach theoretically
from a consistent fully microscopic
approach. Hydrogen-induced reactions measured today are necessary
benchmarks for future nuclear reaction theories. Direct reactions such as
quasi-free scattering or transfer, offer
the possibility of extracting information on the intrinsic angular momentum of the removed nucleon. From
the experimental viewpoint, solid or
liquid hydrogen leads to a maximum
luminosity for a given energy loss in
the target. In addition, hydrogen has
polarization capabilities despite it requires dedicated special techniques.
Finally, proton-induced reactions lead
to unique sensitivity and selectivity to
nuclear single-particle structure. Hydrogen is used to perform inelastic excitations and proton induced knockout
reactions such as (p,2p), (p,pn), and
possibly nucleon-pair removal (p,3p),
which has not been much investigated
in exotic nuclei, partly due to the low
cross-sections. Each of these reaction mechanisms highlights specific
structure aspects of the nucleus. On
the theoretical side, proton elastic and
inelastic scattering has been deeply
investigated. The distorted-wave Born
approximation or coupled channels
formalisms are the most often used
to analyze inclusive or differential
cross-sections and extract structure
information such as nuclear radii or
deformation lengths. Exclusive quasifree scattering (p,2p) measurements
have also provided quantitative spectroscopic information when analyzed
through the distorted-wave impulse
approximation formalism. Consistent
results compared to (e,e9p) have been
found. Today, new formalisms and reaction codes toward unstable nuclei
studies are being developed [1–3].
For an optimal use of proton-induced reactions, a variety of hydrogen
targets have been developed in the last
decades [4]. Among them, MINOS is
a device to pursue the highest lumi-
and the role of three-body forces and
continuum states at and beyond the
neutron drip-line.
Figure 1. View of MINOS inside the DALI2 gamma array. The MINOS system is
hosted in the Spin-Isospin Laboratory at the RIKEN Nishina Center.
nosity for studies of the rarest isotopes
and for kinematically complete measurements.
MINOS
MINOS is a new device composed
of a very thick liquid hydrogen target
and a time projection chamber surrounding the target [5]. A schematic
view of MINOS is shown in Figure
1 where the target thickness is 150 ~
mm, while the target thickness can
be changed according to the requirement of an experiment. Since a typical reaction cross-section of a nucleus
is on the order of 1 barn (10–24 cm2),
the target thickness (6.1023/cm2) corresponds to a mean-free path, and
thus it is expected that an incident
nucleus is subject to some reaction
with a high probability in the target!
It has the advantageous geometry of
being free of any absorbing material
around the target and can therefore be
efficiently surrounded by any type of
radiation detector. The target is cooled
down to about 20 degrees Kelvin by
a cryogenic system located remotely
from the reaction zone. Note that such
a target could generally not be used in
standard in-beam gamma or invariant mass measurement because of its
18
thickness. Both in terms of energy loss
and spatial extension, it would degrade
too much the final energy resolution in
most applications. In order to avoid
degradation of the energy resolution,
a vertex tracker, technically chosen to
be a time projection chamber (TPC)
based on a Micromegas amplification
stage [6, 7], is positioned around the
target. The design goal of the TPC is
to determine the vertex of the reaction with a precision better than 5 mm
FWHM and to achieve a total detection efficiency of better than 80% for
either proton from a (p,2p) reaction.
MINOS is readout by a dedicated
electronics based on the AGET chips
developed within the framework of
the international GET project [8]. MINOS is the first detector to run with
these new-generation chips.
The system was entirely developed
at the Commissariat à l’Energie Atomique et aux Energies Alternatives
(CEA) in France. MINOS has been
used at the RIBF since 2014. This
compact combination is the first of
its kind in nuclear physics. The first
physics questions to be investigated
are the mechanisms of shell evolution
in neutron rich nuclei, the origin of
di-neutron correlations in halo nuclei,
Shell Evolution and First 2+
Excitation Energies in Unstable
Nuclei
Shell evolution along isotopic and
isotonic chains is a known feature of
atomic nuclei and is specifically represented by modifications of nuclear
shell gaps over the whole nuclear
chart. These shell modifications have
mostly been characterized through
systematic studies of low-lying states
of unstable nuclei. A comprehensive
picture of the shell evolution as a function of neutron and proton number is
not yet reached even though an appreciable number of theoretical works has
been performed and several microscopic mechanisms related to fundamental aspects of the nucleon-nucleon
interaction are currently discussed
as possible origins of shell evolution
[9–13]. In-beam gamma coupled to
fast nucleon removal has been shown
to be a powerful technique for the first
spectroscopy of bound excited states
of the most exotic isotopes. The use
of the uniquely high primary beam intensities at the RIBF and the coupling
of MINOS and the DALI2 array [14]
are the core of a new proposal for scientific program (PSP) at RIBF. This
project called SEASTAR aims at accessing new first excitation energies
in even-even nuclei from Ar to Zr isotopes. SEASTAR aims at the spectroscopy of closed (sub)shell nuclei 78Ni
and 110Zr, as well as nuclei in the vicinity of the closed subshell nuclei 48S
and 60Ca. A further study of the onset
of deformation at and beyond N = 40
is also targeted along isotopic chains
from Z = 22 to 26. Collectivity at and
beyond N ~ = ~60 will be investigated
in Kr, Se and Sr isotopes. This Physics
program was initiated in April–May
2014 where the first spectroscopy of
and 78Ni were successfully
performed. A second campaign dedicated to heavier nuclei from Zn to Zr
was successfully completed in May
2015.
Origin of Di-Neutron Correlations
in Halo Nuclei
One of the most exciting phenomena in exotic nuclei may be the
appearance of neutron halos in light
neutron drip-line nuclei. Since their
discovery by I. Tanihata in 1985 from
the measurement of reaction crosssections [15], they are now widely
studied. Nevertheless, it appears that
all previous measurements, although
providing unique insight into the halo
structure, may lack pieces of information. As an example, previous invariant mass experiments do not measure
the excited-core component in the halo
nucleus ground state wave function,
recently argued to be of importance as
part of the neutron-neutron pairing in
such systems [16]. Previous analysis
may have also underestimated the role
of final state interactions (FSI) to extract the nature of the halo.
We proposed a program to deepen
our understanding of the di-neutron
formation in He, Li, Be, and B halos
by performing a fully exclusive measurement of halo spectroscopy via
(p,pn) neutron quasi-free scattering.
The main aspects of this measurement are a first multipole decomposition from quasi-free scattering at large
momentum transfer to minimize FSI,
the measurement of neutron-neutron
relative momentum in the projectile
frame by use of the SAMURAI large
acceptance spectrometer [17] and the
NEBULA neutron array and tagging
of core excitation from prompt gamma
detection with DALI2.
Such a measurement requires 3fold and 4-fold coincidences and the
targeted kinematical region to minimize FSI leads to a rather small cross-
section. These aspects of the measurement require high luminosity that can
be provided by the MINOS target
system while preserving energy resolution. In general, the above physics
cases will benefit from a factor 100
with RIBF beams and MINOS compared to previous experiments.
In order to properly take into account the effect of FSI in the neutron
decay process following the quasifree scattering, a new framework has
been recently developed to analyze
such experiments [2, 3]. It is usually
said that the angular correlation of the
two neutrons after breakup is sensitive
to the correlations between the two
neutrons in the halo. What Y. Kikuchi
shows is different: the inclusive angular distribution of the two neutrons
is very sensitive to the final state interaction during the decay of the unbound neutron. The projection of the
relative momentum distribution of the
two neutrons is not the same and one
would indeed quantify badly the cigar
and di-neutron components by neglecting the final state interaction. On
the other hand, the two components of
the halo, interpreted within the model
mentioned above, can be recovered
60
80
100
Three-Body Forces and
Continuum Effects:
Spectroscopy at and Beyond the
Neutron Drip-Line
Light oxygen nuclei at and beyond
the neutron drip-line have also been
presented recently as a benchmark for
nuclear structure [18–21]. Although
28O gains energy from neutron (N =
20) and proton (Z = 8) shell closures, it
is known to be unbound since 15 years
ago [22]. The location of the drip-line
at N = 16 in C, N and O is known not
to be reproduced by microscopic models with 2-body interaction only.
Three-nucleon interactions become progressively important as one
moves toward neutron-rich isotopes.
Otsuka and collaborators [19] have
demonstrated that the two-pion exchange (a.k.a. Fujita-Miyazawa) term
of 3NFs is responsible for repulsive
NNN3LO
NNN3LO3NNNLO
Exp
120
140
160
180
with a selection on the relative core
and neutron momentum as illustrated
by these two distributions. Such distributions are part of the objectives
of the experiment. Kubota from CNS
and RIKEN and A. Corsi from CEA
Saclay are spokespersons of this program.
Ω24 MeV
ΛSRG 2.0 fm1
Eg.s. MeV
66Cr, 72Fe,
14
O
16
O
22
O
24
O
28
O
Figure 2. Binding energies of oxygen isotopes. Published experimental values
and theoretical calculations from the self-consistent Green’s function theory are
compared (see text for details). Courtesy of C. Barbieri and A. Cippolone, University of Surrey.
contributions to the shell structure
when the neutron-proton difference
increases. This is now fully confirmed
by ab-initio calculations. The binding
energies obtained through self-consistent Green’s function theory [20] are
shown in Figure 2. The dashed line
includes only 3NF effects induced
by two nucleon forces (see Ref. [20]
for details) and neglects 3NFs in the
NNLO term in the chiral Hamiltonian,
the major term of which is the FujitaMiyazawa force. When the latter are
included (full line), all experimental binding energies are reproduced
within numerical accuracy. In particular, the increase of binding energies
is counteracted by a repulsion of the
d3/2 state, key to explain the anomalous drip-line at 24O [19]. The results
of [20] also show that the very same
mechanism determines the drip-lines
of the neighboring nitrogen and fluorine isotopes as well.
In this physics case, the mass of
28O is the key quantity to be determined experimentally. We proposed
to measure the decay energy of 28O
with an invariant mass method. The
proposed experiment aims at producing 28O via proton removal from 29F
and determining the 28O mass by measuring momentum vectors of the four
neutrons together with the 24O core.
Y. Kondo from the Tokyo Institute
of Technology is the spokesperson of
this program. The still low detection
efficiency for neutrons and low beam
intensity of 29F makes this experiment
extremely challenging. For this a very
thick target is necessary. The Vertex
reconstruction offered by MINOS
is necessary not to spoil the energy
resolution due to the beam kinetic energy spread in the target. A detection
efficiency for multi neutrons can be
enhanced by combining new neutron
detector arrays to the existing NEBULA array. The NeuLAND array, constructed for future FAIR experiments,
20
will be installed at RIBF for several
years. It will increase the four-neutron
detection. Recently a proposal to construct a new neutron detector array to
combine with NEBULA has been approved in France. The combination of
the high intensities of RIBF, the large
acceptance SAMURAI spectrometer, high detection efficiency from
NEBULA and additional arrays and
MINOS form a world unique setup
for the spectroscopy of nuclear resonances beyond the neutron drip-line.
Perspectives
Today is an exciting time for nuclear structure research: key exotic
nuclei to understand the mechanisms
of shell evolution with isospin are in
reach thanks to intensities available at
the Radioactive Isotope Beam Factory
of RIKEN. A new physics program
based on the use of the MINOS device
allows an optimal use of the RIBF
capabilities and access the most neutron-rich nuclei. The exploration of
the most exotic nuclei with MINOS at
the RIBF has just started and perspectives are bright. A few years from now,
when a primary beam of heavy ions
such as 238U, 124Xe will be available at
several hundreds of pnA or one pmA at
the RIBF, candidates for doubly magic
nuclei such as 48S, 60Ca or 100Sn could
be at reach from gamma spectroscopy
with the SEASTAR setup within a reasonable beam time. The development
of new beams at high intensity, such as
76Ge, could offer new opportunities in
this venture. These experiments will
provide exceptional information to
deepen our understanding of nuclear
shell evolution well beyond stability.
These studies will be further investigated at upcoming new generation
facilities.
In the case of in-beam gamma experiments, the current limitation of the
setup used at the RIBF is the intrinsic
and spatial (size of the individual detectors) resolution of the DALI2 array.
The use of high-resolution with high
granularity (pulse shape) gamma detectors would open new opportunities
for high-resolution spectroscopy of
heavy nuclei (beyond tin isotopes) or
even-odd nuclei with high-level density away from stability produced at
low intensity. The study of even-odd
nuclei allows a deeper insight into the
orbitals at play in the structure of the
nuclear region under study.
The investigation of specific phenomena for rare isotopes can often
be determined only by missing-mass
spectroscopy from which the absolute energy of the populated states can
be determined. In these experiments,
sufficient energy resolution can be
obtained, usually by use of a thin target. For experiments that require a
few MeV energy resolution, the use
of an extended target such as MINOS
would be extremely beneficial to significantly improve the luminosity. A
natural evolution of the concept would
be the replacement of the time-projection chamber by highly segmented Si
detectors for high resolution tracking
combined with total kinetic energy
detectors for recoil protons and to perform quasi-free scattering measurements. Physics questions such as the
excitation energy dependence of clustering in neutron-rich nuclei could be
investigated this way.
Acknowledgments
The authors thank their collaborators from the Commissariat à lʼEnergie
Atomique et aux Energies Alternatives (CEA), the RIKEN Nishina Center, the University of Tokyo, the Tokyo
Institute of Technology, the Center for
Nuclear Study (CNS), and the Laboratoire de Physique Corpusculaire
(LPC) of Caen in the development of
the mentioned physics program.
This work has been made possible thanks to the European Research
Council (ERC) through the ERC Starting Grant funding MINOS-258567.
The validation phase of MINOS, development of the SEASTAR physics
program, and first physics campaign at
the RIBF was supported by the longterm JSPS fellowship L-13520.
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Alexandre Obertelli
CEA Saclay, IRFU,
Service de Physique Nucléaire,
France
Tomohiro Uesaka
RIKEN Nishina Center, Japan
Filler?
The HADES Pion Beam Facility
Introduction
The quest for unraveling the origin of confinement and spontaneous
breaking of chiral symmetry have
been the driving force for hadron and
nuclear matter physics over the last
two decades. Both processes are responsible for the generation of mass
of all hadronic matter around us [1].
The High Acceptance DiElectron
Spectrometer (www-hades.gsi.de) has
been designed and put into operation
in 2003 to search for signatures of a
(partial) restoration of chiral symmetry, then thought to be observable by
measuring in-medium (shift of pole)
masses of the vector mesons [2, 3].
Electromagnetic decays of the lowmass vector mesons, in particular the r
meson, represent a formidable choice
since they can decay exclusively into
a pair of leptons. Hence, in-medium
decays become observable by reconstructing the invariant mass of the lepton pairs recorded in the spectrometer.
During more than 20 years of research on the emissivity of strongly
interacting matter formed in collisions of heavy ions, at energies rang–
ing from √ s = 2.3 GeV up to a 2 TeV
per N-N pair, radiation off the medium has been unambiguously identified [4, 5]. Using reconstructed four
momentum vectors of lepton pairs
respective spectral distributions have
successfully been used as thermometer, barometer and chronometer of
the evolving fireball [6, 7]. An excitation function of lepton pair production
has also been measured at the RHIC
–
for energies between 20.0 ≤ √ s/GeV
≤ 200. With HADES, the emissivity
of baryon dominated matter has been
–
investigated at SIS18 energies 2.4 √ s
< 3.2 GeV. In contrast to the results at
high beam energies, where the radiation in the spectral region below the
22
vector meson pole masses can essentially be explained as p+p– annihilation in the s-channel, at low beam
energies the radiation of the fireball is
better understood as electromagnetic
decays of baryonic resonances. Assuming a strict Vector Meson Dominance (VMD) theorem the spectral
distribution of the virtual (time-like)
photons reflects in both cases the inmedium properties of the intermediate
r meson. It has been demonstrated,
that the in-medium propagator of the
r meson should be substantially modified by strong coupling of the meson
to baryonic resonance-hole states [8].
An ideal experiment to further test
this hypothesis is the measurement of
exclusive reaction channels of type
p + N → e+e– + N where such resonances are directly excited and decay
into e+e– N final state. To accomplish
this, the recently upgraded HADES
spectrometer can now additionally be
operated with tracked secondary pion
beams. But the physics potential of
this facility goes well beyond: the coupling of, for example, strange mesons
to baryons is of great importance for
the understanding of in-medium kaon
properties and the role of the meson
cloud in hadron structure. Last not
least, p-induced particle production
off nuclei provides ideal conditions to
study medium effects on the meson in
almost recoil-less kinematics.
The Pion Beam Facility at GSI
The combination of secondary
pion beam available at GSI with the
universal HADES detector represents
a worldwide unique facility. The p–beam is generated by a primary 14N
beam, provided by the SIS18 synchrotron, with an intensity close to
the space-charge limit of 0.8–1.0 1011
ions/spill. The pions are then transported to the HADES target, located
33 m downstream of the production
point by a beam-line composed of a
lattice of 7 quadrupole and 2 dipole
magnets, as shown in Figure 1. For
pions with a central momentum (p0)
a transmission of about 56% with
respect to the entrance solid angle is
achieved. The transmission decreases
gradually as the p-momenta depart
from the central momentum, reaching zero for pion momenta of p0 ± 6%.
The transmission can be represented
to first order by a Gaussian distribution with a variance of dp/p0 = 1.5%.
The pion intensity distribution at the
exit of the pion beam-line (last quadrupole) depends on the selected p0,
reaching a maximum of about 106
pions/spill at p0 = 1.0 GeV/c and decreasing to about half of this value at p
= 0.7 GeV/c and 1.3 GeV/c. These intensities are the result of the combined
effect of the beam size at production
target and of the transmission, mostly
driven by the dedicated tuning of the
different magnets and the respective
apertures defined by the vacuum vessels. For a beam of negative pions, the
purity is high and the small contamination by electrons and muons has been
estimated to be lower than a few %. Together with their low interaction probability this contamination does not constitute a handicap for the experiment.
A dedicated tracking system (CERBEROS), composed of two silicon
strip-detectors along the pion chicane
and a start detector right in front of
the HADES spectrometer, has been
developed and successfully commissioned to measure the momentum of
each beam particle. The first silicon
detector station (DET1 in Figure 1) is
located close to the intermediate focus to minimize the effect of multiple
Figure 1. Layout of the HADES pion beam-line with indicated positions of the
pion production target, HADES target position, quadrupoles dipoles, and inbeam tracking detectors (indicated by arrows, DET1, DET2). Sketch of the beam
optics. Note that the second dipole has reverse bias in this notation.
scattering, the second one (DET2) is
installed in the HADES cave close to
the target. While DET1 is mostly sensitive to the momentum offset, DET2
provides additional spatial information to determine the three components
of the pion momentum-vector at the
HADES target point. Each of the 0.3
mm thick, double-sided silicon detectors cover an area of 10 × 10 cm2 and
are segmented into 128 strips oriented
vertically (Y) and horizontally (X).
From the measured positions of the hit
on the two detectors, the pion momentum is reconstructed with a resolution
ranging from 0.1% to 0.3% over the
acceptance window. This allows for a
precise reconstruction of the total center-of-mass energy in pion-nucleon
interactions. The detector is read-out
by an ASIC, n-XYTER [9], providing
as well time as amplitude information, connected to the HADES Trigger
and Read-out Board. During the first
round of experiments the detectors operated stably in the harsh environment
due to a high background level close
to the production target (more than 1
MHz on DET1).
Calculations of the pion beam optics have shown that the beam spot at
the HADES target position exceeds
the diameter of the target (12 mm) and
can cause significant background from
beam interactions in the narrow RICH
beam tube or target holder. In order to
reject this background and to also pro-
vide start time information a position
sensitive detector was placed at 30 cm
in front of the HADES target. This detector consists of two layers, each of
them composed of four, 0.3 mm thick
mono-crystalline diamond wafers (4.7
× 4.7 mm2). This detector provides excellent time resolution (σ = 100 ps), an
efficiency close to 100% for minimum
ionising pions and very high rate capability of <107 hits/cm2.
The HADES detector has been recently upgraded to provide uniform
granularity and improved rate capability. The detector consists (Figure
2, left) of a hadron blind (gthreshold =
18.1) gaseous Ring-Imaging Cherenkov (RICH) detector, four planes of
Mini-Drift Chambers for track reconstruction and a Time-Of-Flight wall
based on scintillators-TOF- (for polar
angles ϑ > 45°) and Resistive Plate
Counters RPC (for ϑ < 45°) supplemented at forward polar angles with
Pre-SHOWER chambers for electron
shower measurement. The detector
features an excellent invariant mass
resolution of ΔM/Me+e– 2.5% at
the r/ω mass poles and electron/
hadron separation (better than 10–5).
With the addition of the RPC in 2010
HADES provides now an excellent
time-of-flight resolution in the full
acceptance of σ = 120 ps and σ = 80
ps for the TOF and RPC systems, respectively. In combination with the
2–3% momentum resolution of the
tracking system the proton/pion and
kaon/pion separation (3 σ) reaches up
to 1.8 GeV/c and ~1.2 GeV/c, respectively (Figure 2, right).
Performance Results from First
Experiments with Pion Beam
The new facility has been operated
in 2014 to take data for p– induced
reaction in two runs with in total two
weeks beam on target. Run 1 was
dedicated to strangeness production
Figure 2. Left: Artist view of the HADES detector. Six identical sectors cover the
full azimuth. The beam location is indicated by the green straight. For measurements, the detectors are pulled tightly to the magnet. Right: Mass of particles
deduced from the time-of-ﬂight and the momentum measurements versus the momentum for particles produced in central Au + Au collisions at 4 AGeV (simulations based on the measured detector performance).
23
3
×10
χ2 / ndf
6.787e+04 / 42
Constant 4.893e+05 ± 2.258e+02
500
1.475 ± 0.000
Mean
Sigma
0.01648 ± 0.00000
400
300
200
100
0
1.2
1.25
1.3
1.35
1.4
1.45
1.5
1.55
1.6
1.65
1.7
p–p–
Figure 3. Left:
Invariant mass distribution from selected p + p elastic collisions. Right: Reconstructed K– mass in p– + C reactions.
in p– induced reactions on a heavy
and light nuclei (C/W) at a beam momentum of p0 = 1.7 GeV/c. The collected data will allow to study the in
medium kaon potential as well as the
f and antikaon meson absorption in
cold nuclear matter. In a more general
perspective, such experiments will
provide new insight in particle production in scattering, charge exchange
or absorption reactions. The goal of
run 2 was to measure the excitation
function of two-pion production in
the p–-p reactions around the pole of
D13(1520) resonance. The exclusive
two pion production data will be analyzed with the partial wave technique
to disentangle the different waves that
build up coherently the measured final
state and will provide a production
amplitude of the r meson production
in the second resonance region. This
information will be used to understand quantitatively how the off-shell
r meson decay into e+e– pairs enters
in the total dilepton production measured simultaneously in this run. This
long awaited result is important for
the understanding of the applicability
of VDM to baryons and the broadening of the r meson observed in protonnucleus (HADES) and heavy ion reactions discussed in the introduction.
Figure 3 (left) shows the distribution of total CMS energy recon-
24
structed from π + p elastic scattering,
selected by angular correlations, indicating no significant background from
non-target interactions and a width
that is dominated by the HADES momentum resolution (σCMS = 1.2%).
The recorded statistics for two-pion
production (π+π– and π–π0) exceeds
the existing data base by about two
orders of magnitude. The right panel
of Figure 3 shows the reconstructed
on-line mass of K– produced in π– + C
reactions for a central beam momentum of 1.7 GeV/c. This preliminary
result already demonstrates the high
purity of the K– selection which will
allow studying K– production on nuclei of increasing mass size with unprecedented precision.
Outlook
It is expected that the HADES
pion beam program will be continued in 2017 after the SIS18 has been
upgraded to serve as injector for the
FAIR facility. For 2016 the HADES
collaboration plans to complement the
detector by a large area electromagnetic calorimeter (ECAL). The ECAL
for HADES will be built from 978 lead
glass modules and will replace the PreShower detector. The calorimeter will
enable measurements of real photons
emitted from nuclear matter, neutral
meson production via their photonic
decays (for example, h/p → gg), and
further improve electron identification.
The latter is crucial for the operation
at higher energies available at SIS100
of FAIR. For p–-N reactions the reconstruction of neutral mesons is essential
to complete the database for partial
wave analysis (PWA). Furthermore,
a concept is developed to operate the
RICH UV-photon detector based on
multi-anode photo multipliers instead
of the existing Multiwire Proportional
Chambers with CsI photocathodes.
The latter project is a synergy between
the HADES and the CBM RICH construction.
References
1. T. Lee, NPA538 (1992) 3.
2. G. Brown and M. Rho, PRL 66 (1991)
2720.
3. T. Hatsuda and S. Lee, PRC 46 (1992)
34.
4. G. Agakichiev et al., CERES Collaboration. EPJ C 41 (2005) 475.
5. G. Agakichiev et al., HADES collaboration. PLB 690 (2010) 118.
6. H. Specht for the NA60 collaboration.
AIP Conf. Proc. 1322 (2010) 1.
7. R. Rapp and H. van Hees, Thermal
Dileptons as Fireball Thermometer and
Chronometer. arXiv:1411.4612 (2014).
8. H. van Hees and R. Rapp, NPA 806
(2008) 339.
9. A. Brogna et al., NIM A 568 (2006) 301.
Piotr Salabura
Jagellonian University Kraków
for the HADES Collaboration
Joachim Stroth
Goethe University Frankfurt
Laura Fabbietti
Technische Universität München
impact and applications
Toward Applications of β-NMR Spectroscopy in
Chemistry and Biochemistry
Introduction
Applications of nuclear spectroscopic techniques are well established
in chemistry and biochemistry, where,
for example, conventional nuclear
magnetic resonance (NMR) spectroscopy is an indispensable analytical tool
[1]. NMR is used routinely to identify
small organic molecules in quality
control, and in more complex research
applications to elucidate structure
and dynamics of large biomolecules
such as proteins and nucleic acids.
Additionally, magnetic resonance
(MR) scanners are available at most
large hospitals for imaging, and it is
now even possible to acquire affordable desk top NMR instruments with
permanent magnets, aimed at small
businesses and educational institutions. However, conventional NMR
spectroscopy faces certain limitations,
mainly due to: (1) relatively poor sensitivity and (2) the fact that there are
elements that are difficult to detect,
because of poor NMR response. To
overcome the first problem, a variety
of hyperpolarization techniques have
been developed, reaching nuclear spin
polarization in the % range [2], which
is far beyond what may be achieved
at thermal equilibrium even in strong
external magnetic fields at room temperature. β-detected NMR (β-NMR)
spectroscopy belongs to this family of
specialized NMR techniques, where
considerable nuclear spin polarization is created prior to the NMR measurement. The sensitivity of β-NMR
spectroscopy is further enhanced, as
it is a radioisotope-based technique,
exploiting the detection of anisotropic
emission of β-particles from the spin
polarized nuclei, vide infra, leading
to a billion-fold or higher increase in
sensitivity as compared to conventional NMR spectroscopy on stable
isotopes. In addition to this, some of
the elements which are problematic
in conventional NMR spectroscopy,
such as Mg, Ca, Cu, and Zn, already are or might be accessible with
β-NMR spectroscopy [3–5]. Several
applications of β-NMR spectroscopy
in nuclear, solid state physics, and
materials science have been published
over the past decades [3–14] and references therein, and with the project
described herein, we aim to advance
the applications to solution chemistry
and biochemistry [5].
An example of a potential field of
application for β-NMR spectroscopy
is biological inorganic chemistry.
Some of the biologically most important metal ions are Mg2+, Ca2+, Cu+,
and Zn2+. Thousands of proteins require these metal ions for their function, and divalent cations play a role in
folding of nucleic acids and function
of catalytic RNA. They are involved in
a broad spectrum of enzyme catalyzed
reactions, in practically all phosphate
(e.g., ATP) chemistry, in electron
transport for example in photosynthesis, in regulation of gene expression,
in muscle contraction and many other
fundamental biochemical processes
[15]. Moreover, the electronic closedshell nature of these ions make them
inaccessible to many standard spectroscopic techniques in chemistry. For
Mg2+ it has been phrased beautifully
in the canonical biological inorganic
chemistry textbook by Fraústo da
Silva and Williams [15]: “Magnesium
in biological chemistry is a Cinderella
element: we know its hidden power
and personality only indirectly since
we are unable to label and follow it in
a sensitive manner.” Thus, it is highly
desirable to develop novel techniques
that allow for the characterization of
local structure and dynamics at biomolecular binding sites for these elements.
β-NMR Spectroscopy
In this section we give a brief introduction to β-NMR spectroscopy,
but it is not intended to be a comprehensive review. The interested
reader is referred to the literature. In
β-NMR spectroscopy, radioactive nuclei are initially spin polarized, and
a differential β-particle count rate is
observed in appropriately positioned
detectors, due to the asymmetry of the
β-emission from the spin polarized
nuclei. Two types of response of the
sample may be explored: (1) recording the decrease of the asymmetry as a
function of time after a pulsed creation
of spin polarization, which allows for
direct observation of the spin-lattice
relaxation time, T1; (2) if the sample
is exposed to radiofrequency radiation
with an energy corresponding to an
NMR transition, the spin polarization
decreases, and correspondingly the recorded β-decay asymmetry is reduced.
Thus, both molecular structure and
dynamics at the probe site may be explored. For a more elaborate description of the technique see, for example,
Refs. [9–11]. The first applications of
β-NMR were proposed by F. L. Shapiro in 1958 [12]. Over the past five to
six decades β-NMR spectroscopy has
been successfully applied in nuclear
physics for measurements of the nuclear magnetic dipole moment, electric quadrupole moments, and nuclear
spins, as well as in the field of solidstate physics and materials science
(some of which is conducted at large
scale facilities ISOLDE [3], GANIL
[6], RIKEN [7], TRIUMF [13]) [3–
14]. In chemistry and biochemistry the
advantages of β-NMR spectroscopy
are: (1) high sensitivity, since as few
as 105–107 ions are required to record
the signal and (2) access to chemical
elements that are otherwise difficult to
interrogate spectroscopically. On the
other hand, specific challenges of this
method are: (1) the relatively short
life-times of the employed radio-isotopes, typically no longer than some
seconds (i.e., the experiments must be
performed rapidly) and (2) that the nuclear spin polarization must be created
prior to the experiment. Various ways
of achieving the spin-polarization exist, most of which require either a facility providing radioactive ion beams,
such as ISOLDE at CERN in Geneva,
Switzerland or ISAC at TRIUMF in
Vancouver, Canada, or irradiation of
the sample with spin polarized neutrons [11].
How Did the Idea and Project
Evolve?
Although this section is not strictly
scientific, it is included to illustrate
how the idea developed from a chat
over a cup of coffee, to a more mature
research project, and to publication of
the initial results. It is written by the
last author on this work, to allow for
acknowledgement of the co-authors,
who really came up with the innovative ideas and did all the hard work on
this project. To the reader exclusively
interested in the science of the project,
I recommend that you skip this section.
During beam time for biochemical applications of perturbed angular
correlation (PAC) of γ-rays spectroscopy at ISOLDE-CERN in 2008, Karl
Johnston, a highly skilled solid state
physicist at ISOLDE-CERN raised the
question if there might be interesting
26
applications of β-NMR spectroscopy
in chemistry and biochemistry. At the
time I—like most biophysicist and
chemists—was not even aware of the
existence of this technique. A Ph.D.
student in my group, Monika Stachura
(MS), was involved in the discussions,
and embarked on the project with great
enthusiasm, and Wolf Dietrich Zeitz,
a β-NMR expert, was affiliated as an
adjoint professor of the University of
Copenhagen to support the project. It
soon became clear that we were—of
course—not the first to consider such
applications, and there was already a
substantial amount of work published
on applications of β-NMR in materials science. However, experiments
on aqueous samples, which would allow for much broader applications in
chemistry and possibly even in biochemistry, were not reported in the
literature, except for a spin relaxation
study on hydrated lithium ions, which
we initially overlooked [16]. Thus, we
set out to apply β-NMR to samples in
aqueous solution. The first substantial challenge was to allow for online
experiments on liquid samples in the
high vacuum environment of a beamline. To this end, a differential pumping system was designed and built by
a very talented post doc, Alexander
Gottberg (AG), and he and MS also
designed a sample chamber specifically for liquid samples. Several experienced researchers were more than
sceptical about this endeavor, including the last author on this work, but
MS was highly dedicated, and drove
the project forward. Following a suggestion by Professor Gerda Neyens
(KU Leuven), who also proposed the
list of isotopes that might be explored,
in 2009 the COLLAPS collaboration
at ISOLDE-CERN got involved, and
generously shared both knowledge
and equipment. In 2010 an application for beam time at ISOLDE/CERN
was submitted and accepted, includ-
ing among others Dr. Magdalena
Kowalska (MK), a very competent
β-NMR spectroscopist with a strong
background in atomic and nuclear
physics, who became equally enthusiastic about the project. With great
ingenuity and a massive effort mainly
by MS and AG, and with constructive
input and support from a large number
of researchers, especially MK, everything was set for 31Mg beam time in
August 2012. The experiments were
successful, and resonance frequencies of 31Mg implanted into a liquid
sample were recorded, vide infra. The
results of this pilot study have been
published recently [5]. The project
has clearly required the convergence
of a broad spectrum of expertise from
nuclear physics over engineering to
biochemistry, the cross-fertilization
that may occur more or less accidently when scientists from various
fields are present at a large-scale facility, and a great, independent, and
passionate effort by AG and MS. For
future studies along these lines, beam
times for 29,31Mg and 58,74,75Cu have
been granted at ISOLDE-CERN [44,
45], and a proposal submitted to TRIUMF (Canada) is pending technical issues. The Knowledge Transfer
Fund at CERN supported the project
financially, and at ISOLDE-CERN
a new beam-line—VITO—has been
commissioned to host, as one of two
permanent experimental stations, a
β-NMR instrument for liquid samples.
Finally and importantly, the European
Research Council (ERC) has recently
provided a substantial grant to MK,
aiming to advance this work further
over the next 5–6 years.
First Measurement of an NMR
Spectrum for Species in Solution
Using β-NMR
β-NMR spectroscopy is conceptually very similar to conventional
NMR on stable isotopes. However, as
Figure 1. Left: The radioactive ion beam enters toward the sample. The continuous gray line shows the laser light (used
to create the nuclear spin polarization, see the text) overlapped with the ion beam. Right: The blue luminescence shows
the laser beam impinging on the liquid drop.
most chemistry and biochemistry occurs in solution, liquid samples had to
be introduced at the end station of the
beam-line at ISOLDE-CERN. Various
options to allow for this were considered, including differential pumping
or thin foils encapsulating the sample.
Using thin foils (carbon and polyimide films), it turned out to be difficult, with a 30 keV ion beam, to obtain
both decent beam penetration and sufficient mechanical strength to sustain
the pressure difference between the
sample and the beam-line vacuum.
However, it may be worthwhile to
pursue this approach at higher beam
energies. Thus, a differential pumping
system allowing for a pressure gradient of six orders of magnitude was designed and fitted into 30 cm of space
available at the β-NMR setup belonging to the COLLAPS collaboration.
The overall design will be published
elsewhere, but a schematic view is
presented in Figure 1. Additionally, a
sample chamber was specifically designed for liquids samples, including a
liquid feedthrough allowing for introduction of a liquid sample at the measurement position inside the chamber.
The beam time with spin polarized
31Mg beam took place in 2012. The po-
larization was achieved using optical
pumping. The lasers as well as several
other parts and equipment were kindly
provided and operated by the COL-
LAPS collaboration. For the proofof-principle experiment we selected
an ionic liquid, 1-ethyl-3-methyl-imidazolium acetate (EMIM-Ac), as the
solvent, because it has exceedingly
low vapor pressure. Thus, introduc-
Figure 2. β -NMR spectrum of 31Mg+ implanted into ionic liquid EMIM-Ac in an
external magnetic field of 0.3 T. Experimental data points are shown with error
bars, and the fit is displayed as a full line.
27
ing various gases (He, Ar, and air) into
the chamber, beam penetration and
conservation of spin polarization during passage through the gas could be
systematically tested as a function of
gas pressure above the sample. The results were encouraging, demonstrating
that a 61 keV 31Mg+ beam penetrates
He gas in the sample chamber up to a
pressure of about 0.1 mbar, and that the
spin polarization is also preserved up
to this pressure [5]. Although it is not
quite sufficient to allow for an aqueous
sample in the setup, it indicates that
this should be possible with further development of the differential pumping
system. The recorded NMR spectrum
is shown in Figure 2. The two resonances are interpreted as originating
from 31Mg ions implanted into the
ionic liquid (3882.9 kHz) and into the
last aluminum part of the pumping system (3887.8 kHz) [5], respectively.
Outlook on Chemical and
Biochemical Applications
The continuation of this project
will encompass a series of test experiments, such as binding of Mg2+ to a
fluorophore in the ionic liquid solution (i.e., a molecule that changes its
fluorescence upon binding of Mg2+).
Using a Mg2+ sensitive fluorophore,
the binding may be observed independently by fluorescence spectroscopy. Since we aim to explore the
binding of metal ions to biomolecules
in solution, the fluorophore is a convenient test system, to elucidate if a
change in resonance frequency (from
Mg2+ implanted into the pure ionic
liquid solution) may be observed using the β-NMR setup at ISOLDE.
For the experiments on Mg2+ it may
be a challenge to achieve sufficiently
small β-NMR line width, to allow for
different resonance frequencies to be
discriminated, as it is known from
conventional 25Mg NMR spectroscopy that the chemical shift span is
28
only about 200 ppm. Next, a feasibility study will be carried out, exploring which, if any, Cu-isotope displays
most favorable nuclear properties for
β-NMR spectroscopy.
A key consideration when searching for relevant applications of
β-NMR, is the fact that radioisotopes
with lifetimes only up to seconds-minutes are useful, because the spin-lattice
relaxation time is usually on this time
scale or shorter, and thus spin polarization is lost on this time scale after
implantation into the sample. That is,
experiments must be conducted with a
biochemical sample “ready” to rapidly
accommodate the radioisotope in the
binding site of interest. In this respect
the applications in chemistry and biochemistry are fundamentally different
from solid state and materials science
applications, where the properties of
the material may be explored in a more
general sense with a β-NMR probe. In
biochemistry the identity of the probe
ion will usually be important, as it is
the biochemistry of this particular element and its interaction with biomolecules that is to be investigated. An
obvious choice for biochemical applications is metal ions displaying relatively fast ligand exchange, and this is
indeed a property of most biologically
relevant metal ions. Combined with
the lack of useful spectroscopic techniques to elucidate the biochemistry
of important metal ions such as Mg2+,
Ca2+, Cu+, or Zn2+, this appears to be
a field where interesting systems may
be investigated, and where β-NMR
may contribute with unique spectroscopic characterization of the role of
these metal ions. To be more specific,
we illustrate these overarching ideas
with three concrete examples where
metal ions are important for macromolecular folding, for catalysis, and
function of biosensors: (1) the role
of Mg2+ in the folding of nucleic acids (DNA and RNA). In collaboration
with the group of Prof. Roland K. O.
Sigel, University of Zürich, we aim to
elucidate the metal site structure at a
high affinity magnesium binding site
of the so-called κ motif of a group II
intron, which is a key element in the
folding of this biomolecule [17]; (2)
exploring the local structure at Mg2+
binding sites in biochemically important macromolecular catalysts in solution: The metal site structure at the
dinuclear magnesium binding site of
catalytic RNA and protein phosphoryltransferases display very similar
architecture in the crystalline state,
despite the fundamentally different
biomacromolecular matrix embedding
[18]; (3) Finally, if the test experiments on Cu β-NMR are successful,
we will attempt to elucidate the metal
site structure of the Cu+ biosensor
CueR in solution, in order to add to
existing knowledge on what gives rise
to the very high affinity and selectivity
of this protein for binding of Cu+ [19].
Summary
In summary, with the current work,
we hope to have provided an account
of the considerations and experimental design leading to the first steps
toward application of β-NMR spectroscopy to solution chemistry and
biochemistry. Although there is still
quite some way to go before these
goals are accomplished, we believe
that they are within reach. There are
most likely other applications, that we
have not yet realized, and that may be
initiated once the technique becomes
more well known in the chemistry and
biochemistry societies.
Acknowledgments
Yorick Blumenfeld and the COLLAPS collaboration are acknowledged
for their great support throughout the
project, and Andrew MacFarlane for
reading and commenting on the manuscript.
CERN-ISOLDE is acknowledged
for beam-time grants and technical
support; the Danish Center for Scientific Computing for resources, the
Danish Council for Independent Research | Natural Sciences, the Knowledge Transfer Fund at CERN, the EU,
and FP7 ENSAR (no. 262010) are
thanked for financial support.
References
1. J. Keeler, Understanding NMR Spectroscopy, 2nd ed., Wiley 2010; http://
www.nobelprize.org/nobel_prizes/
chemistry/laureates/2002/wuthrichlecture.html
2. J. H. Ardenkjær-Larsen et al., Proc.
Natl. Acad. Sci. USA 100 (2003) 10158.
3. G. Neyens et al., Phys. Rev. Lett. 94
(2005) 022501.
4. D.T. Yordanov et al., Phys. Rev. Lett.
99 (2007) 212501.
5. A. Gottberg et al., ChemPhysChem 15
(2014) 3929.
6. K. Shimada et al., Phys. Lett. B 714
(2012) 246.
7. K. Matsuta et al., Hyperfine Interact.
220 (2013) 21.
8. I. McKenzie et al., J. Am. Chem. Soc.
136 (2014) 7833.
9. M. Matthias et al., Phys. Rev. A 4
(1971) 1626.
10. W. D. Brewer, Hyperfine Interact. 12
(1982) 173.
11. H. Ackermann et al., “β-radiation detected nuclear magnetic resonance and
nuclear spin relaxation” Hyperfine Interactions of Defects in Semiconductors, Elsevier, 325–337 (1992).
12. F. L. Shapiro, Usp. Fiz. Nauk 65
(1958) 133.
13. A. Voss et al., J. Phys. G: Nucl. Part.
Phys. 41 (2014) 015104.
14. W. A. MacFarlane et al., Phys. Rev. B
90 (2014) 214422.
15. J. J. R. Frausto da Silva and R. J. P.
Williams, The Biological Chemistry
of the Elements, Oxford University
Press, 2001.
16. P. Heitjans et al., J. Non-Cryst. Solids
131–133 (1991) 1053.
17. D. Donghi et al., Nucleic Acids Res.
41 (2013) 2489.
18. M. R. Stahley and S. A. Strobel, Science 309 (2005) 1587.
19. A Changela et al., Science 301 (2003)
1383.
Monika Stachura
CERN and
Department of Chemistry,
University of Copenhagen
Alexander Gottberg
CERN and TRIUMF
Magdalena Kowalska
CERN
Karl Johnston
CERN and
Experimentalphysik,
Universität des Saarlandes
Lars Hemmingsen
Department of Chemistry,
University of Copenhagen
Filler
meeting reports
STORI’14: 9th International Conference on Nuclear
Physics at Storage Rings
The STORI’14 conference was
held from 29 September to 3 October
2014 at Sankt Goar, Germany, a picturesque little town, located at the Rhine
River close to the famous “Loreley”
within the UNESCO world heritage
“Mittleres Rheintal” (Figure 1). It was
hosted by the GSI Helmholtzzentrum
für Schwerionenforschung, Darmstadt, Germany. The conference was
the ninth of its kind, and followed the
previous conferences held at Lund, St.
Petersburg, Bernkastel-Kues, Bloomington, Uppsala, Jülich, Lanzhou, and
Frascati.
The purpose of the conference was
to provide a forum for the interna-
tional research community, including
accelerator experts as well as experimentalists working at storage rings
and theoreticians, for the presentation and discussion of all aspects of
nuclear physics at storage rings and
related fields. In this spirit the topics
covered:
• a large variety of physics experiments concerning not only
nuclear physics, but also atomic
physics, hadron physics, fundamental symmetries and interactions, subnucleonic degrees
of freedom, and accelerator
physics,
• technologies for providing
cooled, stored stable and radioactive beams and their diagnostics, and
• instrumentation for various inring experiments.
Special emphasis was also put on
perspectives at future facilities, presently under construction or planned.
In addition, some related fields, like
physics and techniques of ion traps and
electrostatic rings, were also featured.
In spite of the variety of physics
questions addressed, which often are
quite diverse, it was realized that the
common basis is the research instru-
Figure 1. Attendees of the STORI’14 conference (photo by M. Lestinsky).
30
meeting reports
ment used: all experiments benefit
from the unrivaled potential provided
by using stored and cooled beams. In
this spirit the conference offered the
opportunity for a lively discussion of
common (not only technical) problems, and for exchanging new and
challenging ideas.
The conference was received with
significant interest among the community with an all-time record of 120
participants from 20 countries all over
the world. The scientific program consisted of 68 plenary oral presentations,
including 9 invited review talks, 25 invited topical talks, and 33 contributed
talks, as well as 45 poster presentations.
The conference opened with two
review talks, one by I. Meshkov,
covering various aspects of storage
ring operation and beam cooling, and
the other by K. Langanke, who gave
an impressive overview on modern
quests in nuclear astrophysics from
the theoretical point of view. The field
of physics experiments at storage
rings was covered by two review talks
given by P. Woods on nuclear structure
and nuclear astrophysics experiments,
and by A. Khoukaz on hadron physics experiments. All aspects of atomic
physics with highly charged heavy
ions at storage rings were covered by
a review presented by A. Surzhykov,
whereas review talks by K. Blaum and
H. Schmidt covered the fields of ion
traps, and electrostatic storage rings,
respectively. The series of review talks
was continued by impressive presentations on fundamental symmetries
and interactions by K. Jungmann, and
on future radioactive beam facilities
by S. Gales. The conference program
was completed by a number of topical
invited talks and contributed presentations, covering all aspects and topics
of the conference discussed above.
In particular, the major new facilities
which offer great perspectives for the
field were also discussed. These are
the HIAF project in China, the NICA
project in Russia, the RIKEN RareRI Ring in Japan, the TSR@ISOLDE
project at CERN and the international
FAIR project in Germany.
One evening was devoted to the
well-attended poster session, which
opened the opportunity to discuss a
good number of interesting topics in
a relaxed atmosphere. In the closing
session a summary of the conference
was presented. For this purpose the
organizers had invited three young
scientists who actively participated in
the conference to present their point of
view of the conference week, instead
of inviting an experienced senior scientist for this duty. S. Kraft-Bermuth,
D. Doherty, and S. Litvinov presented
impressive summaries covering the
three fields of atomic physics, nuclear
physics, and accelerator physics, and
there was common agreement, that
this “experiment” was a full success.
Throughout the conference, active
discussions during the sessions were
continued during coffee and lunch
breaks for which sunny weather and
the garden of the conference location Schloss Rheinfels provided a
spectacular ambience (Figure 1). The
participants also enjoyed the conference excursion which introduced
them to the UNESCO world heritage
“Mittleres Rheintal” and its world famous collection of castles by a boat
trip along the Rhine river from Sankt
Goar to Rüdesheim. After a short hike
at Rüdesheim with spectacular views
on the Rhine valley the boat trip was
continued with a stop at Bacharach for
a wine tasting in the yards of a winery.
During the conference dinner held
at the Rheinfels Castle awards for the
three best poster presentations were
provided. The winners were M. Dolinska, M. von Schmid, and F. Suzaki.
The awards were sponsored by the
representatives of the journal Physica
Scripta, which was also chosen to publish the proceedings of the STORI’14
conference.
During a meeting of the International Advisory Committee it was
decided that the next STORI conference STORI’17 will be organized by
the RIKEN Nishina Center, Tokio,
and will be held at Kazawa in Japan.
Having in mind that within the next
three years a number of new storage
ring facilities will come into operation, providing a lot of interesting experimental opportunities for our community, we are looking forward to an
interesting conference program of the
next STORI conference in 2017.
Peter Egelhof,
Yuri Litvinov,
and Markus Steck
GSI Helmholtzzentrum für
Schwerionenforschung,
Darmstadt, Germany
Filler?
meeting reports
FAIR 2014: A Vibrant EPS Conference on the Future of
Nuclear and Hadron Science in Europe
Figure 1. Attendees of FAIR 2014.
Finding new forms of matter, investigating its fascinating complexity,
and understanding the formation of
elements are only three of the many
intriguing questions in nuclear and
hadron research and drive the construction of FAIR, one of the largest
nuclear research facilities worldwide.
FAIR14 was focused on the status and
prospects of the experimental facilities at FAIR.
The International Conference on
Science and Technology for FAIR in
Europe took place in Worms, Germany, 13–17 October 2014 (http://
fair2014.gsi.de), jointly organized by
the Nuclear Physics Division of EPS,
GSI, and FAIR. FAIR (Facility for Antiproton and Ion Research, http://www.
fair-center.eu) is a new international
research facility on the premises of
32
GSI, the Helmholtz Centre for Heavy
Ion Research in Darmstadt, Germany
(http://www.gsi.de). With about 3,000
users in nuclear, atomic, and hadron
physics, it will be one of the largest
facilities worldwide and the center for
nuclear research in Europe. About 250
scientists from 25 countries and from
4 continents have met at Worms and
discussed the vibrant science and the
unique capabilities compared to other
research opportunities worldwide.
World-leading experts from all fields
of nuclear science presented the status
and development of the experimental
branches APPA, CBM, NUSTAR, and
PANDA planned at FAIR and their respective physics prospects and discovery potential with special emphasis
on complementarity and competition
(Figure 1). Efficient use of the beams,
large statistics, and unparalleled resolution are the cornerstones for the success of FAIR and its underlying physics. This will be possible, for example,
with cooled antiproton beams for hadron and atomic physics to understand
the basic structure of matter, radioactive ion beams for the understanding
of the formation of elements in the
universe, and laser and ion beams for
plasma physics for more macroscopic
studies.
The research program of APPA
(Atomic, Plasma Physics and Applications) covers a broad range from
atomic physics (SPARC and FLAIR)
to plasma physics (HedgeHOB and
WDM) and further on to biophysics
and materials research (BIOMAT).
Wilfried Nörtershäuser (TU Darmstadt) presented an overview of the
meeting reports
research program of SPARC (Stored
Particles Atomic Research Collaboration). Atoms with electrons bound in
extreme electromagnetic fields and
in short and very intense field pulses
allow precision tests of QED under
extreme conditions. Antonio di Piazza
(Heidelberg) elaborated on the critical background electromagnetic fields
for testing QED. It was demonstrated
that the experiments utilize the unique
features of FAIR: very heavy highly
charged ions, storage rings, and trapping facilities. In close symbioses, the
FLAIR collaboration, here presented
by Dimitri Budker (HI Mainz), uses
the antiprotons from FAIR for tests of
matter/anti-matter symmetries. Eberhard Widmann (Vienna) illuminated
the advantages of the FLAIR conditions in comparison to low-energy
antiprotons at CERN and showed this
could be utilized in an early stage if
the transfer of antiprotons from the
production target of FAIR to the ESR
could be installed. Advanced detection techniques and spectroscopic
tools from these collaborations were
shown by Uwe Spillmann and Danyal
Winters (GSI). Emily Lamour (Paris)
presented the FISIC project at Spiral
II for slow ion collisions with fast intense ion beams, which is not competing with any of the SPARC proposals.
A very interesting spectroscopic tool
with unique possibilities at FAIR was
presented by Toshiyuki Azuma (Tokyo) where atomic states in relativistic heavy ions are excited resonantly
in a crystal. It is one of the early experiments of SPARC with the aim to
excite the 1s electron of H-like Uranium to the 2p state available from the
SIS100.
For HedgeHob (High Energy Density Matter Generated by Heavy Ion
Beams), Alexander Golubev (Moscow), described our so far poor knowledge of basic physical properties of
matter under extreme conditions of
high energy density. In this context,
the so-called equation-of-state, static
and dynamic physical properties, and
opacity of warm dense matter (WDM)
are of fundamental importance for
various branches of basic and applied
physics. At FAIR, the HedgeHob
and WDM collaborations can generate dense plasma samples of a large
volume and uniform physical conditions, similar to those in the interiors
of stars, brown dwarfs, and giant gas
planets. This will enable studies of
the fundamental properties of such
matter in so far unexplored regions.
In his talk, David Riley (Belfast) discussed the potential of plasma physics
experiments at FAIR with respect to
those carried out at competing facilities, showing the uniqueness of FAIR
in this area on an international stage.
Elaborate tools for the diagnostic of
the plasma states will be necessary, as
pointed out by Vincent Bagnoud, Paul
Neumayer, and Lev Shestov (GSI) in
their talks.
Biophysics within BIOMAT was
presented by Marco Durante (GSI).
He gave an impressive account of applications of FAIR high-energy beams
in space radiation research, theranostics, and cancer therapy. He showed
that FAIR brings cosmic radiation into
the laboratory to study biological effects of space radiation, test electronic
satellite equipment, and select optimum radiation protection conditions
for space missions. An instrumental
development will employ high energy
protons from FAIR that have a potential for theranostics (i.e., simultaneous
high-resolution imaging and therapy
of small metastasis). As also shown
by A. Constantinescu (GSI), FAIR
will be the test-bed for this innovative technique with potential applications in future therapy. The status and
first experiments in material sciences
within BIOMAT were reported by
Maik Lang (University of Tennessee
Knoxville) as well as new instrumentation by Daniel Severin (GSI). At the
FAIR facility, the simultaneous exposure of materials to multiple extreme
conditions such as high pressure, high
temperature, and extreme energy deposition becomes possible, for example, by irradiating samples in diamond
anvil cells. With that transformation
pathways can be dramatically altered
leading to the formation of new states
of materials, quite far from thermodynamic equilibrium. This innovative experimental approach will allow
BIOMAT to probe materials under
extreme conditions, such as in compressed and heated minerals of Earth’s
interior.
The exploration of the QCD phase
diagram was one of the main topics
of the conference and the main focus
for the Compressed Baryonic Matter (CBM) experiment. Alexander
Schmah (LBNL Berkeley) presented
the latest results of the search for the
first-order phase transition and the
QCD critical point at large net-baryon
densities. The STAR collaboration
made intriguing observations when
scanning the beam energy at RHIC
down to FAIR energies; however, for
a final conclusion data with higher
statistics are needed. The diagnostic power of electromagnetic probes
of QCD matter produced in heavyion collisions was discussed by Ralf
Rapp (Texas A&M University), the
corresponding data on di-lepton production measured by STAR at RHIC
and HADES at GSI were presented by
Zhangbu Xu (LBNL Berkeley), and
Jerzy Pietraszko (GSI), respectively.
Anar Rustamov (GSI) reported on
new high precision data measured in
proton-proton and Be+Be collisions at
CERN-SPS by the NA61 experiment;
these data serve as an important reference for heavy collision systems. The
physics case and the status of preparation of the future CBM experiment
meeting reports
at FAIR was presented by Norbert
Herrmann (University of Heidelberg),
the planned first measurements with
CBM were discussed by Peter Senger
(GSI). Modern instrumentation plays
a decisive role in future heavy-ion experiments. This topic was covered by
Luciano Musa (CERN) who reported
on monolithic pixel detectors for
high-precision vertexing and tracking
in high-rate and high-multiplicity collisions, and by Hans-Rudolf Schmidt
(U Tübingen) who gave a review on
modern 3D-detectors.
An overview of the big scientific
questions addressed by NUSTAR
(Nuclear Structure, Astrophysics and
Reactions) was given by Nasser Kalantar-Nayestanaki. He also outlined
the achievements of various detector
systems and their early implementation for pilot experiments at the existing GSI facilities. In more detail, the
status of the Super-FRS construction
was presented by Haik Simon (GSI),
and the uniqueness of experiments at
Super-FRS, R3B, and the FAIR storage ring complex were highlighted
by Isao Tanihata (Osaka), Thomas
Aumann (TU Darmstadt), and Yuri
Litvinov (GSI). The NUSTAR Collaboration is well underway on its continuous transition from GSI to FAIR
and has already identified science
goals for the first phase of experiments
with the FAIR Super-FRS. Building
on in-flight separation at relativistic
energies, high momentum resolution experiments, and reaction studies with external and internal targets,
the NUSTAR facilities at FAIR are
outstanding on the worldwide scale,
and will offer unique nuclear physics
opportunities in years to come. Examples of novel experimental setups,
cutting-edge technologies, and recently obtained results were presented
by Daniel Rodriguez (University of
Granada) and Klaus Blaum (MPI Hei-
34
delberg) (precision experiments with
trapped charged particles), Alison
Bruce (University of Brighton) and
Silvia Lenzi (University of Padova)
(spectroscopy), and Julien Taieb (CEA
Orsay) (fission of actinide nuclei and
applications). Tremendous progress in
nuclear structure models was achieved
in the last years with ab-initio calculations, as was reported by Peter
Navratil (Triumf). It was important to
see how other major next-generation
facilities like SPIRAL2 (GANIL,
France), RIBF (RIKEN, Japan), and
FRIB (MSU, USA) develop facilities
and instruments that are complementary to NUSTAR@FAIR.
The structure of hadrons and the
binding among quarks to form hadrons of all kinds is the main focus of
the PANDA experiment (antiprotonAnnihilations at Darmstadt). Because
of the complexity of the strong force
and its bound states, both aspects
exhibit a lot of very important open
questions. Abhay Deshpande (Stony
Brook) summarized the status, prospects, and open issues in the structure
of nucleons, while Adam Szczepaniak
(University of Indiana) reported on
open problems in spectroscopy and
dynamics of hadrons. The status of the
PANDA experiment and its potential
for early experiments have been presented by James Ritman (FZ Jülich)
and Paola Gianotti (LN Frascati).
PANDA utilizes an antiproton beam
for its experiments, which annihilates
with varying incident momenta on
different kinds of targets. With, for
example, exotics hadronic systems
with charm and strangeness, electromagnetic form-factors of the proton,
DVCS, hyper nuclear physics as well
as in-medium effects and light quark
phenomena the PANDA experiment
has a broad physics program and complements a lot of other activities worldwide. They have been highlighted by
renowned experts in the respective
fields. Open and hidden charm states
have been investigated by BaBar and
Belle in the past and is continued by
BES3 and Belle-2. Their sensitivity
and the large window of opportunities
due to the uniqueness of PANDA was
detailed by Sören Lange (University
of Gießen), while Sebastian Neubert
(CERN) presented the results and excellent prospects from LHCB at LHC
at CERN. In the light quark domain
the new JLAB-12 facility opens up
many opportunities for the discovery
of light exotics and for improved measurements of the structure of nucleons.
Patrizia Rossi (JLAB) gave a very inspiring talk on all these aspects underlining the complementarity of the
approaches and the need for a complete experimental picture to arrive at
a decisive understanding. Finally, two
colloquial talks on strangeness of nuclei and novel tests of QCD at FAIR
from Ryugo Hayano (University of
Tokyo) and Stan Brodsky (SLAC),
respectively, exemplified how diverse,
complex, and fundamental the experiments in hadron physics at FAIR can
be. All this has been accompanied by
many talks about the challenges in
hardware development as well as in
lattice gauge calculations by Gunnar
Bali (University of Regensburg) and
aspects of the antiproton production
facility by Klaus Knie (GSI).
The five days in Worms showed
an enormous progress and many new
ideas. It has been demonstrated that
the science case for FAIR is excellent and improved compared to the
initial proposals with opportunities
for breaking the frontiers in all aspects
of FAIR physics, like the quest of numerous forms of subatomic matter on
various scales.
Klaus Peters
GSI, Germany
meeting reports
ARIS 2014
Figure 1. Conference photo taken in Ito Hall.
The second conference on Advances in Radioactive Isotope Science, ARIS 2014, was held in Tokyo
on 1–6 June 2014. The first ARIS conference was held in 2011 in Leuven,
Belgium, with the ultimate goal to
create the “flagship conference” series
on the science on radioactive isotopes
including exotic nuclei produced by
RI (Rare- or Radioactive-Isotope)
beams. The ARIS conference is, in
fact, the merged entity of the International Conference on Exotic Nuclei
and Atomic Masses (ENAM) and the
International Conference on Radioactive Nuclear Beams (RNB), which
were previously two major conferences on radioactive isotopes with a
substantial overlap. Science with radioactive isotopes is being developed
very fast with strong contributions
from recent and near-future constructions/upgrades of RI-beam facilities
over the world, as reported in Nuclear
Physics News frequently. Thus, it was
very timely and important to overview
the present status and future perspectives of the field by holding the second
ARIS conference.
The ARIS 2014 was co-organized
by the RIKEN Nishina Center for
Accelerator-Based Science and the
Center for Nuclear Study, the University of Tokyo. From these institutions, Hideto En’yo and Takaharu
Otsuka served as Chair and Co-chair,
respectively. The scientific secretaries
were Tohru Motobayashi, Ken Yako,
Juzo Zenihiro, and Pieter Doornenbal.
ARIS 2014 was sponsored by the International Union of Pure and Applied
Physics (IUPAP) and supported by
several Japanese institutions and societies.
On the first day of the ARIS 2014
conference (1 June), a public lecture
was presented to a general audience,
which we shall come back to later. The
main program started on 2 June, and
lasted for five days. The plenary, parallel, and poster sessions were held in
the Ito International Research Center,
which is a conference complex with
rooms suitable for various functions.
The Ito Center is in the Hongo campus
of the University of Tokyo, located in
the central part of Tokyo.
The total number of registrants
amounted to 407, which was even
slightly beyond the expectation of the
organizers. The conference photo, displayed in Figure 1, indicates that the
conference venue was almost filled to
capacity. Such a large number of attendees highlights the importance of
the activities covered by the conference and the enthusiasm of the researchers in the field.
After the welcome address by the
Conference Chair, Hideto En’yo, and
the speech by Hideyuki Sakai on behalf of the C12 commission of IUPAP,
meeting reports
congratulatory addresses were presented by three distinguished guests:
Dr. Hiroaki Aihara (Vice President,
University of Tokyo), Dr. Maki Kawai
(Executive Director, RIKEN), and
Mr. Satoshi Odoi (Director, Office for
Particle and Nuclear Research Promotion, Ministry of Education, Culture,
Sports, Science and Technology). The
scientific sessions were then opened
by the keynote speech, which was delivered by Robert Janssens with great
enthusiasm (Figure 2). He started by
addressing the Big Questions (quoting
NAS report “Nuclear Physics: Exploring the Heart of Matter”),
• How did visible matter come into
being and how does it evolve?
• How does subatomic matter organize itself and what phenomena emerge?
• Are the fundamental interactions
that are basic to the structure of
matter fully understood?
• How can the knowledge and
technological progress provided
by nuclear physics best be used
to benefit society?
Robert provided a thorough overview
of many important topics and results
that were reported after the first ARIS
conference in 2011.
Figure 2. Robert Janssens presenting
the keynote speech.
36
In fact, these questions also appeared amongst some of the major
objectives of ARIS 2014 also. The
scientific scope of ARIS 2014 aimed
to preserve many of the subjects that
were received well at the first ARIS
conference and the preceding ENAM
and RNB conferences. The science
program was composed of the following subjects:
1. Nuclear structure
2. Nuclear astrophysics
3. Fundamental symmetries and
interactions
4. Nuclear reactions and responses
5. Nuclear properties including
atomic masses and fundamental constants, nuclear moments
and radii, rare decay modes,
and nuclei at the drip-lines
6. Nuclear EOS and its implications
7. Heaviest elements and fission
8. Radioactive isotope production and developments of experimental devices
9. Computational developments
10. Applications
11. Other related issues
The presentations at ARIS 2014
showed that, over the wide variety of
subjects listed above, these Big Questions have been investigated extensively and have been answered to a
good extent with some highlights, for
instance, the experimental verification
of the new magic number N = 34 as a
consequence of shell evolution.
A total of 48 plenary talks were
given on 2–6 June covering all the
subjects mentioned in the scientific
scope above. Exciting reports covering subjects from mass measurements
to the structure and reactions of exotic
nuclei, to superheavy elements and to
the applications of radioisotopes, were
presented by speakers from 18 different countries. Two parallel sessions,
each with presentations taking place
in three separate rooms, ran on both 3
and 6 June; a total of 82 oral presentations were given in these sessions.
Although all of the rooms used during the parallel sessions were located
quite close to one another, the situation was certainly not ideal for the audience and the organizers appreciate
their understanding.
The speakers of the plenary and
parallel sessions were nominated
based on recommendations from the
International Advisory Committee.
The organizers are grateful for their
tremendous contributions.
There were two separate poster
sessions with a total of 239 posters
on display. The organizers were particularly pleased by the large number
of young presenters. In one of the
poster sessions, SEIKO EG&G Co.,
Ltd. very kindly covered the cost of
the refreshments (a crown session),
which provided a cozy and lively atmosphere.
We introduced the Best Poster
Award for young presenters at ARIS
2014. Based on the reports by evaluators chaired by Susumu Shimoura,
seven posters were granted this Award,
and the awards ceremony took place
during the closing session.
The afternoon of 4 June was allocated as free time, and the conference
banquet took place in the evening in
Chinzanso, where the participants enjoyed watching the fiery glows of fireflies in the Japanese-style garden.
On 6 June, ARIS 2014 came to
an end after many exciting talks and
lively discussions. Angela Bracco
gave an excellent summary talk (Figure 3), covering various major aspects
from numerous reports presented during the conference.
It may be interesting to note some
statistical features of ARIS 2014.
There was a broad distribution of participants that included many nations,
meeting reports
reflecting the expansion of the field.
The female contributions were 14%
for the participants, 23% for the plenary talks, and 21% for the oral presentations.
The conference proceedings will be
published electronically as a volume
of the JPS Conference Proceedings
(http://jpscp.jps.jp/) in early 2015, after
all articles have been refereed. Details
of the talks will be provided there.
As mentioned above, a public lecture was given on 1 June to a general
audience that included high-school
students. Michael Thoennessen gave
a very pedagogical lecture on the history of isotopes in English with Japanese subtitles, being coordinated by
Dr. Kaoru Takeuchi (a science writer).
As the majority of the audience was
Japanese with a limited capability of
English, this was certainly a challenge.
Despite this, however, the lecture was
well received and the audience enjoyed the informative talk. The public
lecture included a panel discussion by
Kaoru Takeuchi, Yoshiko En’yo, and
Nori Aoi, for instance, on their careers
as nuclear physicists.
Further details on ARIS 2014 can
be found at the website: https://ribf.
riken.jp/ARIS2014/.
The host institutes and location of
the next ARIS conference were decided during ARIS 2014. It will be
co-organized by NSCL/MSU and
TRIUMF and will take place North
America in 2017.
Figure 3. Angela Bracco presenting the summary talk.
In the author’s opinion, the ARIS
2011 and 2014 have been very successful, and the ARIS conference series has
adopted the role of the flagship conference of the field. I hope that this feature will be reinforced in the next ARIS
conference with even greater success.
ARIS 2014 was made possible by
the contributions and efforts of many
people, from secretariats to International Advisory, Organizing and Program Committees, and of course, the
participants. All of the contributions
are very much appreciated. All photos
shown here were taken by Narumasa
Miyauchi.
TAKAHARU OTSUKA
Department of Physics and Center for
Nuclear Study, University of Tokyo
National Superconducting
Cyclotron Laboratory,
Michigan State University
Filler?
37
news and views
European Strategy for Particle Physics
The CERN convention, originally
established in 1954, describes the mission of the CERN organization. In
addition to the construction and operation of one or more international laboratories for research on high-energy
particles with particle accelerators, it
calls for the organization and sponsoring of international co-operation
with other laboratories. Following the
second mandate, the CERN Council
launched an initiative to establish the
European Strategy for Particle Physics, which was adopted by the Council
in its special session in 2006. Adoption of the strategy also implies regular updates, with an interval of about
five years.
Preparation for the first update of
the Strategy started in 2011, by the
Council setting up the European Strategy Preparatory Group and the European Strategy Group. The Preparatory
Group consisted of selected members
of the CERN Scientific Policy Committee and the European Committee
for Future Accelerators. They were
nominated by their corresponding
committees and ratified by the Council. The Strategy Group consists of
representatives from the member
states, the CERN Director General,
and representatives of major European
national laboratories. The President of
the Council, representatives from the
candidate states for accession and the
associate member states, as well as
from the observer states and organizations were also invited.
The mandate of the Preparatory
Group was to prepare scientific input
that summarized the status of elementary particle physics. It also participated in the Strategy Group meetings
and provided scientific assistance. The
role of the Strategy Group was to prepare a draft of the updated European
38
Strategy for Particle Physics based on
the scientific input from the Preparatory Group and their own investigation on other related issues such as
international relations, outreach, education, and knowledge transfer. Both
groups were chaired by the Scientific
Secretary for the Strategy Session of
Council, who had been elected by the
Council. Furthermore, the Strategy
Group was assisted by the Strategy
Secretariat, consisting of the SPC
chair, ECFA chair, and a representative of the large national laboratories
group.
The first event of the update process was the Open Symposium in
September 2012 held in Cracow. Its
scientific program was organized by
the Preparatory Group with review
talks on a variety of subjects including physics at the high energy frontier,
precision physics, neutrinos, strong
interactions and nuclear physics, astroparticle physics, as well as theory,
accelerators, and detector technology.
Special attention was paid to ensure
long discussion time for the community to express their views. A summary
of the symposium was documented
in a Physics Briefing Book (CERNESG-005) by the Preparatory Group
together with the scientific secretaries
of the Symposium, and was submitted
to the Strategy Group.
The second event was a weeklong Strategy Drafting meeting by
the Strategy Group in January 2013
in Erice. After recapitulating the contents of the Physics Briefing Book, the
Strategy Group discussed strategy issues. Reflecting on the discussion, the
Strategy Secretariat generated the first
draft of the updated Strategy using the
original European Strategy as a starting point. This was then discussed line
by line by the Strategy Group, which
led to a new draft. After several iterations, the final draft was produced and
received unanimous approval from
the Strategy Group members, and was
then submitted to the president of the
Council as a proposal to the Council.
At the same time, it was released to
the community so that the community
could give their feed-back to their
Council delegates for discussion by
the Council, which took place during
the March Council session in 2013. In
the Council discussion the final draft
for the updated Strategy was produced
and then formally adopted as the European Strategy for Particle Physics
(CERN-Council-S/106) at the special
session of the Council in May 2013 in
Brussels.
The updated Strategy identifies
four high priority scientific programs:
Exploitation of LHC including its upgrade; R&D for future high energy
frontier accelerators; e+e– linear colliders with an interest to participate in
the International Linear Collider project that has been under consideration
in Japan; and R&D on the neutrino detectors for a possible future long baseline neutrino program in Japan and the
United States.
This was a direct reflection of the
following achievements made after
the original Strategy had been established: Successful operation of LHC at
√s = 7 and 8 TeV resulting in the discovery of the Higgs-like particle with
a mass in agreement with the Standard Model expectation, completion
of the ILC Technical Design Report
and the measurement of the third neutrino mixing angle, q13, that was at the
larger end of the expected range. After
the discovery of the “Higgs” particle,
precision measurements of its properties are now required. With the measured value of q13, it appears that there
news and views
exists a fair chance to observe CP violation in the neutrino oscillations with
the existing accelerators. For the next
strategy update in around 2018, new
results from the LHC at √s = 13 to 14
TeV may indicate a direction for the
next high energy frontier accelerator,
and R&D for the key technologies for
various accelerator options must be
carried out for possible decision making at that time.
In parallel, well-motivated unique
experiments for precision measurements, in particular in quark and lepton flavor physics, are identified as
a promising alternative approach to
look for physics beyond the Standard
Model with moderate costs. It is also a
place where national laboratories can
provide facilities.
The vital role played by theoretical
physics is well recognized for its double role: on one hand it shows a wide
range of vision for new physics and on
the other hand it provides essential information to understand experimental
measurements.
To ensure the success of future experiments, which will have to operate
in more and more challenging envi-
ronments, not only the R&D on detector technology but also the infrastructure for large detector construction
and computing are identified as areas
to be sustained.
As in the original Strategy, close
relation with nuclear and astroparticle
physics is recognized as crucial and
increased collaborative work through
NuPECC and APPEC, respectively, is
stressed.
In the updated Strategy, the coordinating role of CERN in the European
participation in possible future global
projects is recognized and the commitment by the particle physics community to further strengthen the relation with the European Commission
and related bodies is expressed.
Other issues, which were already
discussed in the original Strategy and
are now receiving even stronger attention in the update, are those related
to the social impact such as outreach,
education, and knowledge transfer.
Lastly, it also outlines a recommended framework for the future update process of the Strategy.
The two-step procedure with the
first step being to compile the scien-
tific issues and to gather community
opinion by the Preparatory Group, and
the second step to draft the Strategy
Update by the Strategy Group where
many of its members were close to the
decision-making body of the CERN
member states, was very successful
in converging on a Strategy that was
accepted by both the community and
CERN member states. After the formal adoption of the updated Strategy
by the Council, it has been used as a
guideline for the European particle
physics program, such as the Medium
Term Plan for CERN. Although it is
the European Strategy, special attention was paid to look at it from the
international context. It is worth noting that the Strategy was seen as a
reference point by the Particle Physics Project Prioritization Panel in the
United States for their recommendation for the future of the U.S. particle
physics program to the Department of
Energy.
Tatsuya Nakada
Laboratory for High Energy Physics,
EPFL
Filler?
in memoriam
In Memoriam: George C. Morrison (1930–2015)
George C. Morrison
Born 14 May 1930, George C. Morrison graduated from the University
of Glasgow with his first degree and
then studied at the University of Chicago before moving to the Argonne
National Laboratory in Chicago. His
scientific reputation was built in the
field of nuclear structure physics, in
particular heavy-ion research and isobaric analogue states. In 1973 George
moved back to the United Kingdom
and took up a chair of Nuclear Structure Physics at the University of Birmingham, appointed by Professor Bill
Burcham.
At that time, the Birmingham Nuclear Physics group’s research was
centered on the Radial Ridge Cyclotron, which was the only accelerator
in the United Kingdom capable of
producing beams of polarized deuterons and then later the only facility in
the world with a polarized 3He beam.
George’s drive and enthusiasm led the
Birmingham Nuclear Structure group
to a leading position within Europe in
the use of polarized beams for nuclear
structure studies.
George also initiated a program of
heavy-ion research on the Variable
Energy Cyclotron at Harwell, which
became a significant component of
the research of the Birmingham group
over the subsequent years. This program continued at the Daresbury
Nuclear Structure Facility (NSF), the
planning and construction of which
started in 1974 with the Birmingham
group providing components such as
the polarized ion source and a large
scattering chamber. The NSF was
commissioned in the early 1980s.
Toward the end of the 1980s
George directed his energy and enthusiasm into the leadership roles of first
deputy dean and then in 1988 dean
of the Faculty of Science and Engineering. He followed this with head
of Physics and Space Research (later
renamed Physics and Astronomy) in
1990. He served on the UK SERC Nuclear Physics Board, was chair of the
SERC Nuclear Structure Committee,
Filler?
40
and a member of NuPECC. He was
elected to the Executive Committee
of the European Physical Society and
was chairman of the Editorial Board
of Europhysics News. Post retirement
in 1997, as emeritus professor, George
continued in this latter role, as did his
work as a non-executive director of
the Birmingham Children’s Hospital
NHS Trust.
George was passionate about nuclear physics, a fierce debater and
strong defender of the interests of
students both as head of the Nuclear
Physics group and head of department. It is these characteristics that
helped set the Birmingham Nuclear
Physics group on its present course
and for which colleagues both of the
present and past generations will be
eternally grateful. George was a great
man, extremely proud of his achievements and endlessly proud of his family. George passed away after a period
of extended illness, surrounded by his
family, on Monday, 2 March 2015.
Condolences may be conveyed
through the Birmingham Nuclear
Physics group ([email protected].
uk).
Martin Freer
Birmingham Nuclear Physics Group,
Birmingham, UK
calendar
2015
June 29–July 2
Kraków, Poland. 5th International Symposium on Nuclear Symmetry Energy (NuSYM15)
http://nusym15.ifj.edu.pl/
June 29–July 3
Pisa, Italy. Chiral Dynamics 2015
http://agenda.infn.it/event/cd2015
July 6–10
Lanzhou, China. 5th International Conference on Proton-emitting Nuclei, PROCON2015
http://procon2015.csp.escience.cn/
July 14–18
Dubna, Russia. International
Conference Nuclear Structure and
Related Topics
http://theor.jinr.ru/~nsrt15/
July 20–24
Pisa, Italy. 30 years with RIBs
and beyond
http://exotic2015.df.unipi.it/index_
file/slide0003.htm
July 28–30
Liverpool, UK. Reflections on the
atomic nucleus
http://ns.ph.liv.ac.uk/
Reflections2015
August 31–September 4
Groningen, The Netherlands.
European Nuclear Physics Conference (EuNPC 2015)
http://www.eunpc2015.org/
September 6–13
Piaski, Poland. 34th Mazurian Lakes Conference on Physics
“Frontiers in Nuclear Physics”
http://www.mazurian.fuw.edu.pl/
September 7–11
Palaiseau, France. Sixth International Conference on Physics
Opportunities at an Electron-Ion
Collider (POETIC6)
http://poetic6.sciencesconf.org/
September 7–12
Sendai, Japan. 12th International
Conference on Hypernuclear and
Strange Particle Physics (HYP2015)
http://lambda.phys.tohoku.ac.jp/
hyp2015/
September 14–19
Kraków, Poland. 5th International Conference on “Collective
Motion in Nuclei under Extreme
Conditions” (COMEX5)
http://comex5.ifj.edu.pl/
September 16–24
Erice, Sicily, Italy. Probing Hadron Structure with Lepton and
Hadron Beams
http://crunch.ikp.physik.
tu-darmstadt.de/erice/2015/
index.php
September 27–October 3
Kobe, Japan. Quark Matter 2015
http://qm2015.riken.jp/
October 19–23
Tokyo, Japan. Fifth International Workshop on Compound-Nuclear Reactions and Related Topics,
CNR*15
http://www.nr.titech.ac.jp/~chiba/
CNR15/index.html
November 10–13
Washington, DC, USA. 12th International Topical Meeting on Nuclear Applications of Accelerators
(AccApp’15)
http://aad.ans.org/meetings.html
December 1–5
Medellín, Colombia. The XI
Latin American Symposium on Nuclear Physics and Applications
http://www.gfnun.unal.edu.co/
LASNPAXI/
2016
August 8–12
Aarhus, Denmark. 23rd European Conference on Few-Body
Problems in Physics
http://owww.phys.au.dk/~fedorov/
EFB23/
September 11–16
Adelaide, Australia. International Conference on Nuclear Physics 2016 - INPC2016
http://www.physics.adelaide.edu.
au/cssm/workshops/inpc2016/
September 11–16
Bruges, Belgium. International
Conference on Nuclear Data for Science and Technology ND2016
http://www.nd2016.eu/
More information available in the Calendar of Events on the NuPECC website: http://www.nupecc.org/
COVER 4
Ad to come

Vol. 25 No. 2

Transcription

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