jaea-researchjaea-research jaea-research 2008-116...
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JAEA
-Research
JAEA-Research
2008-116
─ ZnSシンチレータ、光リフレクタ、及びデジタル信号処理装置の開発 ─
ENGIN-X型1次元シンチレータ中性子検出器の検出器性能向上に関する技術開発
中村 龍也 片桐 政樹 美留町 厚 海老根 守澄筒井 紀彰* 曽山 和彦 Erik Schooneveld* Nigel Rhodes*
Tatsuya NAKAMURA, Masaki KATAGIRI, Atsushi BIRUMACHI, Masumi EBINENoriaki TSUTSUI*, Kazuhiko SOYAMA, Erik Schooneveld* and Nigel Rhodes*
J-PARC センター
J-PARC Center
March 2009
Japan Atomic Energy Agency 日本原子力研究開発機構
JAEA
-Research 2008-116
ENGIN-X
型1次元シンチレータ中性子検出器の検出器性能向上に関する技術開発 ─ ZnS
シンチレータ、光リフレクタ、及びデジタル信号処理装置の開発
─
日本原子力研究開発機構
Development for Upgrading Japanese ENGIN-X Type Linear Scintillation
Neutron Detectors
- Development of New ZnS Scintillator, Light Reflector and Digital Signal
Processing Module -
1
JAEA-Research 2008-116
ENGIN-X 1
ZnS
J-PARC
+ + *1
Erik Schooneveld*2 Nigel Rhodes*2
(2008 12 19 )
ENGIN-X 1 ZnS
ZnS
ZnS
ZnS/10B2O3 ISIS
2 ( 1 Å)
Al
------------------------------------------------------------------------------------------------------------------------
J-PARC 319-1195 2-4+
*1 ( )*2 Rutherford Appleton Laboratory
��
JAEA-Research 2008-116
2
JAEA-Research 2008-116
Development for Upgrading Japanese ENGIN-X Type Linear Scintillation Neutron Detectors
- Development of New ZnS Scintillator, Light Reflector and Digital Signal Processing Module -
Tatsuya NAKAMURA, Masaki KATAGIRI, Atsushi BIRUMACHI+,
Masumi EBINE+, Noriaki TSUTSUI*1, Kazuhiko SOYAMA,
Erik Schooneveld*2 and Nigel Rhodes*2
Materials and Life Science Division, J-PARC Center
Japan Atomic Energy Agency
Tokai-mura, Naka-gun, Ibaraki-ken
(Received December 19, 2008)
New ZnS scintillator, light reflector and digital signal processing modules were developed
to upgrade the Japanese ENGIN-X type linear scintillation neutron detector. The
developed ZnS:Ag/10B2O3 scintillator improved a detector efficiency by a factor 1.2 for
neutrons with a wavelength of 1 Å compared with the ISIS standard scintillator. The
detector maintained a similar gamma sensitivity and multi-count ratio to the present
scintillator. The new light reflector made of an etched-surface aluminum plate was
developed in replace of a light reflector with an acrylic paint coating. The detector
implemented with this reflector exhibited similar detector performances to that with an
acrylic paint coated reflector, securing long-term stability. The digital signal-processing
module incorporating a photon-counting method was successfully developed. The fully
digitalized photon counting system improved temperature stability of neutron counts
significantly compared with the present analogue system.
Keywords: Neutron Detector, Scintillator, Boron Converter, Light Reflector, Digital Signal
Processing, Temperature Stability
------------------------------------------------------------------------------------------------------------------------ + Engineering Services Department, Nuclear Science Research Centre, Tokai Research and
Development Centre *1 Chichibufuji Co. Ltd. *2 Rutherford Appleton Laboratory
����
JAEA-Research 2008-116
JAEA-Research 2008-116
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3
1. 1
2. ENGIN-X 1 27 ch 1
3. ZnS/6LiF ZnS/10B2O3 2
3.1 2
3.2 3
3.3 4
3.3.1 5
3.3.2 Am-Be 6
3.3.3 6
3.3.4 7
4. 8
5. 10
6. 12
12
12
Contents
1. Introduction 1
2. ENGIN-X type linear scintillation neutron detector (27-ch detector) 1
3. Development of ZnS /6LiF and ZnS/10B2O3 scintillator 2
3.1 Specification of developed scintillator 2
3.2 Scintillation light properties: Light yield and decay time 3
3.3 Evaluation of detector performances 4
3.3.1 Experimental methods 5
3.3.2 Evaluation by using an Am-Be neutron source 6
3.3.3 Detector performances plotted with a gamma sensitivity 6
3.3.4 Dependence on neutron wavelength 7
4. Surface etched aluminum reflector 8
5. Digital signal processing with a photon counting method 10
6. Conclusion 12
Acknowledgements 12
References 12
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1.
J-PARC ( )1) /
1
2008
ISIS2) 1
ISIS ENGIN-X 3)
1 1
ENGIN-X 4) ISIS
160 kW
J-PARC 1 MW ISIS
ZnS
2. ENGIN-X 1 27 ch
ENGIN-X
27 ch
27 ch ENGIN-X
1/5 27
PMT 8 2 27 ch
(ENGIN-X )
2 ZnS
2 2 ZnS
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6
1 98
2 (PMT)
2Cn 3 PMT
/ /
PMT5
27
197 mm ( ) X 8.9 mm ( ) X 0.4 mm ( )
3 mm
20
3
3. ZnS/6LiF ZnS/10B2O3
ZnS
ZnS/6LiF ZnS/10B2O3 (6Li10B) 10B
10B 6Li 410B 6Li Q
3.1ZnS:Ag ZnS/6LiF
ZnS 6LiF
ZnS/10B2O3 ZnS H310BO3
600 1
(1) (2) Applied Scintillation Technologies (AST)
(1) AST (4:1) ENGIN-X
AST(4:1) ZnS 6LiF 4 : 1
(2) AST(2:1) ZnS 6LiF 2
(3) (6) JAEA
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JAEA 6Li, 10B
ZnS
(3) : 6Li ZnS Cl Al
(4) : 6Li 0.7 mm
(5) : 6Li ZnS:Ag,Cl
0.4 mm ZnS 8 m
(6) : 10B (H310BO3
10B2O3 )
(0.4 mm )
3.2
30 mm ( 2
) PMT PMT
4 1000
ZnS 100 ns
1~10 s ( )
(6) (ZnS:Ag,Cl/10B2O3)
20% 10% 2
100-20% ( (1)) 0.46 s
(6) 0.29 s 4
ZnS:Ag,Cl ZnS 6LiF
(2)(4)(5) 0.5~0.95 s 10B
(6)
ZnS/10B2O310B2O3
ZnS/6LiF
(6) 4
( 2 100-10% )
(3) ZnS:Ag, Al Al
5 ( 1 s)
Multi Channel Analyzer
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1
(1) (2) (5) (6) (1) (2) (5)6Li (1), (2) AST (5) JAEA
JAEA ZnS/6LiF AST
2
( (3)) (3) 1.7
Al
4 3
(4)
0.7 mm ZnS
180 m
ZnS
10B (6) 6Li
(6) 10B6Li
(6) 6Li 0.1
mm
(6) ( 0.3 mm)6LiF 0.4 mm 3
ZnS
5
ZnS
3.31
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3.3.1
Quiet 4
Am-Be (10 Ci)
Am-Be (1200 x 1200 x 1200 mm3)
750 mm 77 1/s/cm2
1
ZnS
( 1 s) (nrawcounts) 20 s
(n20-us counts) n20-us counts
,1
,
2020
20
scountss
countsscountstrue
countstrue
countstruecountsrawcountmulti
nn
n
nnn
R
20-us 20 s n 1
1%
Quiet 10B Quiet ( 300
mm) 27 ch 2 PMT
PMT Quiet
60Co 3.3 Ci 50 mm
Quiet60Co 1.17 1.33 MeV
ZnS Quiet
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Quiet
Quiet ENGIN-X 1
~50%@ 1 Å ~1 x 10-7
1% Quiet 6 x 10-4 1/s/cm2
3.3.2 Am-Be (1) (6) 27 ch
ISIS5
6
63
1 ISIS (1)
(3) (5) JAEA ZnS:Ag/6LiF 2
(4), (6)
ZnS:Ag,Cl/6LiF ZnS:Ag,Cl/10B2O3 (4)
0.7 mm (6) 10B
3 1 2 (2) (AST(2:1))
(2) (4) (6)
3.3.37 (1) (2) (4) (6) Quiet
(2) (6)
1 x 10-7
( 7 (a) ) (6) (ZnS:Ag,Cl /10B2O3) (2)
(AST(2:1) ) (4) (ZnS:Ag,Cl/6LiF 1109) (6)10B
( 5 ) (2) (6)
(1) 20~30%
7(b) 1%
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(6) 0.2 0.2%
ZnS/10B2O3
(4) 2
0.7 mm
( 5 )
Quiet (2) (4)
(6) 3~5 Quiet
Quiet
(6)
3
3.3.4AST(2:1) ZnS:Ag,Cl/10B2O3 ( (2) (6))
ISIS ROTAX
ROTAX
27 ch
1 x 10-7 0.5% AST(4:1)
-220 mV AST(2:1) ZnS:Ag,Cl/10B2O3 -180mV
8 AST(4:1)
0.3~5 Å
1
2 ( 1 Å
)
3
AST(2:1) ZnS:Ag,Cl/10B2O3 9
ZnS:Ag,Cl/10B2O3 AST(2:1) ZnS:Ag,Cl/10B2O3
1 Å AST(2:1) ( 1
) AST(2:1) 1
ZnS:Ag,Cl/10B2O3
AST(2:1)
ZnS:Ag,Cl/10B2O3
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ZnS:Ag,Cl/10B2O310B
6Li ZnS:Ag,Cl/10B2O3 AST(2:1)
ZnS AST(2:1)
AST(4:1) Quiet 1 Å
2 ZnS:Ag,Cl/10B2O3
Quiet
2
ZnS:Ag,Cl/10B2O310B 6Li
ZnS/10B2O3
4.
( 2 )
AST(4:1)
10 ZnS 400~500 nm
450 nm ISIS (white paint )
(No.4)
Al No.1 No.2 No.3
Al
ZnS
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white paint
( 3)27 ch
white paint ch 17 ch 18 (No.3 No.7)
No.7 No.3
11 No.3
No.7
white paint
ISIS
SUS
SUS
12
White paint
-220 mV 0.01
13 AST(4:1) white paint
ISIS white paint
AST(2:1) ZnS:Ag,Cl/10B2O3
14 AST(2:1) ZnS:Ag,Cl/10B2O3 white paint
AST(2:1)
ZnS:Ag,Cl/10B2O3
20% ZnS:Ag,Cl/10B2O3
4
15 16 AST(2:1) ZnS:Ag,Cl/10B2O3 white paint
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AST(2:1)
ZnS:Ag,Cl/B2O3 10~20
ISIS AST(4:1) white paint
AST(2:1) ZnS:Ag,Cl/10B2O3
5.
ENGIN-X 1
PMT
( PMT )
PMT
ISIS
Field Programmable Gate Array
(FPGA) ZnS
FPGA
FPGA
FPGA
FPGA
4 JAEA
PMT PMT
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Low Voltage Differential Signaling (LVDS)
17
20 50
ISIS +0.017 %/deg
1/6 +0.003 %/deg
PMT +0.02 %/deg
FPGA 1
18 27 ch
1~20
FPGA
( )
27 ch 1
2
19 FPGA
1 s
FPGA
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6.
ENGIN-X
ZnS:Ag,Cl/10B2O3 AST(2:1)
2 ( 1 Å)
1 MW
1) J-PARC: available from < http://j-parc.jp/MatLife/ja/index.html >
2) ISIS: available from <http://www.isis.rl.ac.uk/>
3) ISIS ENGIN-X: available from <http://www.isis.rl.ac.uk/Engineering/>
4) E. M. Schooneveld, et al: “A new neutron sensitive scintillation detector for ENGIN-X”,
ICANS-XVI, 16th Meeting of the International Collaboration on Advanced Neutron Sources,
p.455 (2003)
5) T. Nakamura, et al: “Performance test of the Japanese ENGIN-X type linear scintillation
neutron detector”, JAEA-Research 2007-014 (2007).
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Fig. 1: An image view of Japanese engineering diffractometer, “Takumi”, in the J-PARC/MLF.
Photo. 1: The ENGIN-X diffractometer at ISIS
South bankdetectors
North bankdetectors
Neutron beam
Sample table
South bankdetectors
North bankdetectors
Neutron beam
Sample table
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Photo. 2: A 27-ch fibre-coded detector. An top aluminum foil and detector face
cover were removed for visibility.
81 mm
197
mm
PMTs
Scintillator/reflector grid
81 mm
197
mm
PMTs
Scintillator/reflector grid
Fig. 2: A schematic view of a scintillator / light reflector grid.
Scintillator stripsReflectors
Scintillator stripsReflectors
Scintillator stripsReflectors
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Signal processing, Discrim
inator (G
EM electronics)
Decoder electronics
Data acquisition system
8 PMTs
Scintillator/reflectors grid(27 pixels)
Signal processing, Discrim
inator (G
EM electronics)
Signal processing, Discrim
inator (G
EM electronics)
Decoder electronics
Decoder electronics
Data acquisition system
Data acquisition system
8 PMTs
Scintillator/reflectors grid(27 pixels)
Fig. 3: A schematic view of a 27-ch linear scintillation detector system.
Table. 1: Specifications of scintillator samples
(1) AST*1 AST(4:1) ZnS:Ag,Cl 6LiF 4 :1 0.4 4~5 (-) flexible, thermoplastic
(2) AST AST(2:1) ZnS:Ag,Cl 6LiF 2 :1 0.4 4~5 (-) flexible, thermoplastic
(3) JAEA Ag,Al 1055 ZnS:Ag,Al 6LiF 2.7 :1 0.45 8~9 (1055)*4 non-annealed after sinter
(4) JAEA Ag,Cl 1109 ZnS:Ag,Cl 6LiF 2.7 :1 0.7 4~5 (1109) non-annealed after sinter
(5) JAEA Ag,Cl 2112 ZnS:Ag,Cl 6LiF 2.7 :1 0.4 8~9 (2112) non-annealed after sinter
(6) JAEA ZnS/B2O3 ZnS:Ag,Cl 10B2O3 1.5 :1*2 0.3/0.4*3 4~5 (1109) scintillator layer formed ona glass substrate.
*1 : Applied Scintillation Technologies LTD.*2 : ZnS : H310BO3
*3 : 0.3-mm thick scintillator formed on a 0.4-mm glass substrate.*4 : Numbers in parenthesis denote powder number from Nichia Co LTD.
No. Manu- Sample Scintillation Converter ZnS:6LiF Thickness ZnS particle Notesfacturer name material material (by weight) (mm) size (um)
(1) AST*1 AST(4:1) ZnS:Ag,Cl 6LiF 4 :1 0.4 4~5 (-) flexible, thermoplastic
(2) AST AST(2:1) ZnS:Ag,Cl 6LiF 2 :1 0.4 4~5 (-) flexible, thermoplastic
(3) JAEA Ag,Al 1055 ZnS:Ag,Al 6LiF 2.7 :1 0.45 8~9 (1055)*4 non-annealed after sinter
(4) JAEA Ag,Cl 1109 ZnS:Ag,Cl 6LiF 2.7 :1 0.7 4~5 (1109) non-annealed after sinter
(5) JAEA Ag,Cl 2112 ZnS:Ag,Cl 6LiF 2.7 :1 0.4 8~9 (2112) non-annealed after sinter
(6) JAEA ZnS/B2O3 ZnS:Ag,Cl 10B2O3 1.5 :1*2 0.3/0.4*3 4~5 (1109) scintillator layer formed ona glass substrate.
*1 : Applied Scintillation Technologies LTD.*2 : ZnS : H310BO3
*3 : 0.3-mm thick scintillator formed on a 0.4-mm glass substrate.*4 : Numbers in parenthesis denote powder number from Nichia Co LTD.
No. Manu- Sample Scintillation Converter ZnS:6LiF Thickness ZnS particle Notesfacturer name material material (by weight) (mm) size (um)
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Fig. 4: Normalized signal shapes measured with various scintillators with a bialkali PMT.
The scintillator strips were installed in a light reflector grid. The averaged signals were
displayed.
Table. 2: Scintillation light properties
(1) AST*1 ZnS:Ag,Cl 6LiF 4 :1 0.46 1.44 1.0
(2) AST ZnS:Ag,Cl 6LiF 2 :1 0.50 1.64 0.88
(3) JAEA ZnS:Ag,Al 6LiF 2.7 :1 1.4 3.0 1.69
(4) JAEA ZnS:Ag,Cl 6LiF 2.7 :1 0.95 2.64 (no clear peak)
(5) JAEA ZnS:Ag,Cl 6LiF 2.7 :1 0.86 2.54 0.85
(6) JAEA ZnS:Ag,Cl 10B2O3 1.5 :1*2 0.29 0.82 1.0
*1 : Applied Scintillation Technologies LTD.*2 : ZnS : H310BO3
No. Manu- Scintillation Converter ZnS:6LiF Time Time Relative signal heightfacturer material material (by weight) 100-20% (us) 100-10%(us) (relative peak position)
(1) AST*1 ZnS:Ag,Cl 6LiF 4 :1 0.46 1.44 1.0
(2) AST ZnS:Ag,Cl 6LiF 2 :1 0.50 1.64 0.88
(3) JAEA ZnS:Ag,Al 6LiF 2.7 :1 1.4 3.0 1.69
(4) JAEA ZnS:Ag,Cl 6LiF 2.7 :1 0.95 2.64 (no clear peak)
(5) JAEA ZnS:Ag,Cl 6LiF 2.7 :1 0.86 2.54 0.85
(6) JAEA ZnS:Ag,Cl 10B2O3 1.5 :1*2 0.29 0.82 1.0
*1 : Applied Scintillation Technologies LTD.*2 : ZnS : H310BO3
No. Manu- Scintillation Converter ZnS:6LiF Time Time Relative signal heightfacturer material material (by weight) 100-20% (us) 100-10%(us) (relative peak position)
(1) AST*1 ZnS:Ag,Cl 6LiF 4 :1 0.46 1.44 1.0
(2) AST ZnS:Ag,Cl 6LiF 2 :1 0.50 1.64 0.88
(3) JAEA ZnS:Ag,Al 6LiF 2.7 :1 1.4 3.0 1.69
(4) JAEA ZnS:Ag,Cl 6LiF 2.7 :1 0.95 2.64 (no clear peak)
(5) JAEA ZnS:Ag,Cl 6LiF 2.7 :1 0.86 2.54 0.85
(6) JAEA ZnS:Ag,Cl 10B2O3 1.5 :1*2 0.29 0.82 1.0
*1 : Applied Scintillation Technologies LTD.*2 : ZnS : H310BO3
No. Manu- Scintillation Converter ZnS:6LiF Time Time Relative signal heightfacturer material material (by weight) 100-20% (us) 100-10%(us) (relative peak position)
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Fig. 5: Pulse height distributions measured with various scintillators with a bialkali PMT.
Fig. 6: Neutron counts plotted as a function of a multi-count ratio.
1
10
100
1000
10000
0 100 200 300 400Pulse height, ch
Cou
nts
in 5
00 s
(1) AST(4:1)(2) AST(2:1)(3) ZnS:Ag,Al/LiF 1055(4) ZnS:Ag,Cl/LiF 1109
(3)(4)
(1)
(2)
1
10
100
1000
10000
0 100 200 300 400Pulse height, ch
Cou
nts
in 5
00 s
(1) AST(4:1)(5) ZnS:Ag,Cl/LiF 2111(6) ZnS:Ag,Cl/B2O3
(6)(5)
(1)
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Fig. 7: Detector performances plotted as a function of a gamma sensitivity. (a) detector
efficiency (neutron counts), (b) multi-count ratio and (c) quiet count rate.
(a) Detector efficiency
100
200
300
400
1.E-08 1.E-06 1.E-04 1.E-02
Gamma sensitivity
Neu
tron
coun
ts, c
ps
(1) AST(4:1)(2) AST(2:1)(4) ZnS:Ag,Cl/LiF 1109(6) ZnS:Ag,Cl/B2O3
(b) Multi-count ratio
0
1
2
3
4
1.E-08 1.E-06 1.E-04 1.E-02
Gamma sensitivityM
ulti-
coun
t rat
io, %
(1) AST(4:1)(2) AST(2:1)(4) ZnS:Ag,Cl/LiF 1109(6) ZnS:Ag,Cl/B2O3
(c) Quiet count rate
1.E-05
1.E-04
1.E-03
1.E-02
1.E-08 1.E-06 1.E-04 1.E-02Gamma sensitivity
quie
t cou
nt ra
te, 1
/s/c
m2
(1) AST(4:1)(2) AST(2:1)(4) ZnS:Ag,Cl/LiF 1109(6) ZnS:Ag,Cl/B2O3
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(2) AST(2:1)(3) ZnS/B2O3
Detector efficiency% for 1Å
Gamma sensitivityx 10-7
Multi-count ratio%
Quiet count ratex 10-4 1/s/cm2
56 1 0.9 2 0.5 0.3 2.1 0.5
57 1 1.5 4 0.3 0.3 6.9 1.1
(1) AST(4:1) 46 2 2 1 0.6 0.3 2.1 0.3
Scintillator
(2) AST(2:1)(3) ZnS/B2O3
Detector efficiency% for 1Å
Gamma sensitivityx 10-7
Multi-count ratio%
Quiet count ratex 10-4 1/s/cm2
56 1 0.9 2 0.5 0.3 2.1 0.5
57 1 1.5 4 0.3 0.3 6.9 1.1
(1) AST(4:1) 46 2 2 1 0.6 0.3 2.1 0.3
Scintillator
Table. 3: Scintillator detector performances. The threshold voltages for GEM electronics
were set at -220 mV for AST(4:1) and -180 mV both for AST(2:1) and ZnS/10B2O3
scintillator.
Fig. 8: Count ratios between AST(2:1) and AST(4:1) and between ZnS:Ag,Cl/10B2O3
and AST(4:1) plotted as a function of a neutron wavelength.
0.6
0.8
1
1.2
1.4
1.6
0 1 2 3 4 5 6Wavelength of neutron, Å
Cou
nt ra
tio
AST(2:1) / AST(4:1)ZnS_B2O3 / AST(4:1)
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Fig. 9: Count ratios between ZnS:Ag,Cl/10B2O3 and AST(2:1) plotted as a function of a
neutron wavelength.
Fig. 10: Reflectivity of light reflectors. An ISIS standard reflector is denoted as
white paint. An etching rate is increased from reflector No. 1 to 3 in an order.
0.6
0.8
1
1.2
1.4
0 1 2 3 4 5
Wavelength of neutron, Å
Cou
nt ra
tio, Z
nS_B
2O3
/ AS
T(2:
1)
1e-7 (gamma sensitivity)
1e-6
0
0.5
1
1.5
2
2.5
3
3.5
200 300 400 500 600
Chichibu-no1Chichibu-no2Chichibu-no3Chichibu-no4Al-powder-nhgWhite-spray-ISIS
Rat
io
Wavelength, nm
White paint
No. 4 (non etched)
No. 1
No. 2
No. 3
Al powder
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Photo 3: A white painted reflector grid (ISIS standard, left) and etched aluminum grid
reflectors (No.3 and No.7, right). The reflectors for channel 17 and 18 were replaced
with No.3 and No.7 reflectors for the test.
Fig. 11: Neutron counts measured with surface etched aluminum reflectors. An
AST(4:1) scintillator was installed in the grid.
No. 7 No. 3White painted grid No. 7 No. 3White painted grid No. 7 No. 3White painted grid
0
50
100
150
200
250
100 150 200 250
Thresholdvoltage, mV
Cou
nts
per s
econ
d
w hite paint ref lectoretched Al ref lector (No.3)
etched Al ref lector (No.7)
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Fig. 12: A count ratio in a neighboring pixel through light leakage.
Fig. 13: Detector efficiency (neutron counts) and a multi-count ratio of AST(4:1)
scintillator as a function of a gamma sensitivity.
-0.2
0.0
0.2
0.4
0.6
0.8
50 100 150 200 250 300 350
Threshold voltage, mV
Cou
nt ra
tio in
nei
ghbo
urin
g pi
xel,
%
white paint reflectoretched Al reflector (No.7)
(a) Detector efficiency
0
100
200
300
400
1.E-08 1.E-07 1.E-06 1.E-05 1.E-04Gam m a sens itivity
Cou
nts
per s
econ
d
AST(4:1), white paint reflector etched Al reflector
(b) Multi-count ratio
0
1
2
3
1.E-08 1.E-07 1.E-06 1.E-05 1.E-04Gamma sensitivity
Mul
ti-co
unt r
atio
, %
AST(4:1), white paint reflector etched Al reflector
JAEA-Research 2008-116
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JAEA-Research 2008-116
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27
Fig. 14: Neutron counts measured with white paint and etched surface reflectors.
Fig. 15: Neutron counts and a multi-count ratio of AST(2:1) scintillator as a function of a
gamma sensitivity.
0
100
200
300
400
50 100 150 200 250 300
Threshold voltage, mV
Cou
nts
in c
ps
AST(2:1), white paint
AST(2:1), etched Al No7
ZnS/B2O3, white paint
ZnS/B2O3, etched Al No7
(a) Detector efficiency
0
100
200
300
400
1.E-08 1.E-07 1.E-06 1.E-05 1.E-04Gam m a sens itivity
Cou
nts
per s
econ
d
AST(2:1), white paint reflector etched Al reflector
(b) Multi-count ratio
0
1
2
3
1.E-08 1.E-07 1.E-06 1.E-05 1.E-04Gamma sensitivity
Mul
ti-co
unt r
atio
, %
AST(2:1), white paint reflector etched Al reflector
JAEA-Research 2008-116
− �� −
JAEA-Research 2008-116
− �� −
28
Fig. 16: Neutron counts and a multi-count ratio of ZnS:Ag,Cl/10B2O3 scintillator as a
function of a gamma sensitivity.
Photo 4: A digital signal processing module developed by JAEA.
(a) Detector efficiency
0
100
200
300
400
1.E-08 1.E-07 1.E-06 1.E-05 1.E-04Gamma sensitivity
Cou
nts
per s
econ
d
ZnS/B2O3, white paint reflector etched Al reflector
(b) Multi-count ratio
0
1
2
3
1.E-08 1.E-07 1.E-06 1.E-05 1.E-04Gamma sensitivity
Mul
ti-co
unt r
atio
, %
ZnS/B2O3, white paint reflector etched Al reflector
JAEA-Research 2008-116
− �� −
JAEA-Research 2008-116
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29
Fig. 17: Temperature stability of neutron counts measured with an analogue (a)
and a digital (b) photon counting system.
(a) Analog signal processing (Analogue electronics)
0.990
0.995
1.000
1.005
1.010
0 5 10 15 20 25Time, hr
Nor
mal
ized
cou
nts,
a.u
.
21.4 deg 51 deg
+ 0.017 %/deg
(b) Digital signal processing (FPGA electronics)
0.990
0.995
1.000
1.005
1.010
0 5 10 15 20 25
Time, hr
Nor
mal
ized
cou
nts,
a.u
.
20.6 deg 52.4 deg
+ 0.003 %/deg
JAEA-Research 2008-116
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30
Fig. 18: A gamma sensitivity measured with an analogue and a digital photon
counting system.
Fig. 19: Neutron counts measured with a digital photon counting system as a
function of a coincidence time.
100
150
200
250
0 0.5 1 1.5 2 2.5
Coincidence time, s
Neu
tron
coun
ts, c
ps
1.E-08
1.E-07
1.E-06
1.E-05
0 5 10 15 20Threshold level, s ingle photon num ber
within 2- s coincidence tim e
Gam
ma
sens
itivi
ty
Analog s ignal process ingDigital s ignal process ing
Quiet count is not subtracted.
JAEA-Research 2008-116
− �� −
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