A Novel Measuring System for Detecting and Characterizing

A Novel Measuring System for Detecting and Characterizing

A Novel Measuring System for Detecting and
Characterizing Radioactive Particles
Jani Turunen, Kari Peräjärvi, Roy Pöllänen and Harri Toivonen
STUK-Radiation and Nuclear Safety Authority, P.O. Box 14, Helsinki FIN-00881, Finland
Introduction
Air sample measurement with PANDA
A novel device for non-destructive sample analysis known as PANDA
(Particles And Non-Destructive Analysis) has been designed and built
[1,2]. PANDA broadens the prospects on measurements and analysis of
radioactive samples by applying techniques and instruments normally
used in basic research. These are double-sided silicon strip detectors,
event mode data acquisition and software based coincidences.
For initial tests, the air sample was collected using a Fluoropore air filter
(collection time 2.2 h, total air flow 12.7 m3). The measurement was
started 0.5 h after the collection. The total acquisition time was 3 d 5 h.
30
28
26
24
Detectors
• Alpha
• Beta
• Gamma
• X-ray
• e-
22
20
Y-strip
18
16
14
12
10
8
6
4
2
0
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
X-strip
(a) The filter installed to a sample holder.
(b) Alpha XY-hitmap.
40
214
Counts
212
Po
7.687
30
212
20
Po
8.784
Bi
6.051 (70 %)
6.090 (27 %)
10
Fig. 1. The PANDA (Particles And Non-Destructive Analysis) measurement setup.
0
4
5
6
7
8
9
10
Energy (MeV)
PANDA
(c) Alpha spectrum of X-strip 15.
10000
6000
X-rays from
4000
1000
Experimental data
Fit
Tl
212
50
Bi
Counts
Data recorded in event mode.
• Events timestamped.
• Data stored in database.
singles γ-spectrum
α-gated γ-spectrum
8000
Counts
Two vacuum chambers.
• Sample loading chamber.
• Measurement chamber (Measurement Positions MP1 and MP2).
• The samples are transported between them with a linear feedthrough.
39.858
40
100
30
10
20
MP1
• Screening of large-area samples, location of radioactive particles.
• Double-Sided Silicon Strip Detector (DSSSD) and HPGe detector.
MP2 (under construction).
• Small Si drift detector, with excellent energy resolution.
10
0
0
5
10
15
20
25
30
35
40
45
Energy (keV)
(d) Singles and alpha-gated
gamma spectrum.
50
0
50000
100000
150000
200000
250000
Time (s)
(e) Time behaviour of 212Bi
activity
Fig. 3. An air filter mounted into a sample holder and the results from the measurements [2].
A
PANDA is a measurement setup that can greatly improve the analysis of
air samples in Certified Laboratories. However, the sampling and
subsequent sample preparation must be non-destructive, similar to
sample treatment at Cinderella-type IMS stations.
B
C
F
E
D
A
B
C
D
E
F
Loading chamber
Measurement chamber
DSSSD
HPGe detector
Sample holder
Linear feedthrough
Fig. 2. Top view of PANDA's vacuum chambers.
[1] K. Peräjärvi, J. Hakala, A. Jokinen, I.D. Moore, H. Penttilä, R. Pöllänen, A. Saastamoinen,
H. Toivonen, J. Turunen, J. Äystö, Event mode data acquisition for characterization of
samples containing radioactive particles, IEEE Transactions on Nuclear Science, in press.
[2] J. Turunen, K. Peräjärvi, R. Pöllänen, H. Toivonen, PANDA - A novel instrument for nondestructive sample analysis, Nuclear Instruments and Methods in Physics Research Section
A, submitted.