Download pdf - JAEA-Research · 2013. 2. 25. · 2 JAEA-Research 2008-115 Development of Two-dimensional Scintillator Neutron Detector using Wavelength-shifting Fibres - Development of a Compact

JAEA

-Research

JAEA-Research

2008-115

− J-PARC/MLF 生命物質構造解析装置「iBIX」のためのコンパクト型検出器の開発 −

波長シフトファイバを用いた高検出効率、高位置分解能型2次元シンチレータ中性子検出器の

開発研究

中村龍也　片桐政樹　細谷孝明*　美留町厚海老根守澄　曽山和彦　Erik Schooneveld* Nigel Rhodes*

Tatsuya NAKAMURA, Masaki KATAGIRI, Takaaki HOSOYA*, Atsushi BIRUMACHI*Masumi EBINE, 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 2008-115　

波長シフトファイバを用いた高検出効率、高位置分解能型２次元シンチレータ中性子検出器の開発研究　─ J-PARC/M

LF

生命物質構造解析装置「iBIX

」のためのコンパクト型検出器の開発

─

日本原子力研究開発機構

Development of Two-dimensional Scintillator Neutron Detector

using Wavelength-shifting Fibres

- Development of a Compact Detector for iBIX Instrument in J-PARC/MLF -

1

JAEA-Research 2008-115

2

- J-PARC/MLF iBIX -

J-PARC

*1 + +

Erik Schooneveld*2 Nigel Rhodes*2

(2008 12 19 )

J-PARC/MLF

2

13.3 x 13.3 cm2 69

ISIS 2

------------------------------------------------------------------------------------------------------------------------

J-PARC 319-1195 2-4+

*1

*2 Rutherford Appleton Laboratory, ISIS facility

��

JAEA-Research　2008-115

2


Development of Two-dimensional Scintillator Neutron Detector

using Wavelength-shifting Fibres

- Development of a Compact Detector for iBIX Instrument in J-PARC/MLF -

Tatsuya NAKAMURA, Masaki KATAGIRI, Takaaki HOSOYA*1, Atsushi BIRUMACHI+,

Masumi EBINE+, 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)

A compact two-dimensional neutron detector was developed for iBIX instrument in the

J-PARC/MLF. The specifications required for the detector were a spatial resolution of less

than 1 mm, a detector efficiency of more than 50% for thermal neutrons, a gamma sensitivity

of less than 10-6, detector coverage of around 16 x 16 cm2 with least dead area,

compactness, modularity, and a pulse pair resolution of less than 2 s. The detector

components including new scintillator material, wavelength-shifting fibres, photomultipliers,

amplifier/discriminator electronics, signal processing electronics, time of flight data

acquisition module, were studied in detail and optimized for the purpose. The compact

prototype detector that has a neutron sensitive area of 13.3 x 13.3 cm2 was made and

feasibility of the detector was demonstrated successfully in the experiments at the ISIS

pulsed neutron source.

Keywords: Neutron Detector, Scintillator, Two-dimensional Detector, Wavelength-shifting

Fibre

------------------------------------------------------------------------------------------------------------------------ + Engineering Services Department, Nuclear Science Research Centre, Tokai Research and

Development Center *1 Ibaraki University, Department of Biomolecular Functional Engineering *2 Rutherford Appleton Laboratory, ISIS facility

��

JAEA-Research　2008-115


��

3

1. 1

2. WLSF 2 1

2.1 1

2.2 2

2.3 3

3. 4

3.1 ZnS/10B2O3 4

3.2 6

3.3 8

3.4 / 10

3.5 11

3.6 ToF 12

4. 12

5. ISIS 12

5.1 13

5.2 ToF 13

5.3 13

6. 14

14

14

��


��

4

Contents

1. Introduction 1

2. Two-dimensional WLSF-type scintillator neutron detector 1

2.1 Principle of neutron detection 1

2.2 Detector specifications required for iBIX instrument 2

2.3 Detector design 3

3. Development of detector components for a iBIX detector 4

3.1 ZnS/10B2O3 scintillator 4

3.2 Evaluation of a wavelength-shifting fibre 6

3.3 Multianode photomultiplier 8

3.4 Amplifier/discriminator circuit module for photon counting method 10

3.5 Digital signal processing and encoding electronics 11

3.6 Time of flight data acquisition circuit module 12

4. A prototype 2-d detector system 12

5. Detector performance test at ISIS pulsed neutron source 12

5.1 Spatial resolution 13

5.2 Time of flight measurements 13

5.3 Neutron diffraction measurements 13

6. Conclusion 14

Acknowledgements 14

References 14


�v


− � −

5

1.

2008 5 J-PARC/ (Materials and Life science Facility,

MLF)

JRR3 2

ISIS

MLF 23

1)

2 2

(> 50%@1A) (< 1 mm) (> 16 x 16 cm2)

(> 70%) (< 2 s) ToF

1 100

50

2

10 15

(Wavelength-shifting fibre, WLSF)

WLSF

2

16 19

20

2. WLSF 2

2.1WLSF 1996

D.P. Hutchingson2)

3,4,5)

WLSF


�v


− � −

6

6) WLSF

WLSF

7) 8) 9)

1 ZnS/6LiF WLSFZnS/6LiF 6Li(n, )T

ZnS (4.78 MeV)( 450 nm)

WLSF WLSF

(Photomultiplier, PMT)2 2

X Y 256 WLSFWLSF 90

PMT ( )/ /

2.2

1) (> 50% for thermal neutrons)

2) (< 1 mm )

3) (< 10-7)

4) (> 160 mm x 160 mm)

5) (< 30%)

6)

7) (< 2 s)

8) Time of Flight (ToF)

1 x 1 x 1 mm3

10-100 Å

( MeV

)


− � −


− � −

7

1 mm

1

ToF

2 s

WLSF 2 1 mm

ISIS SXD 35%(1.8 Å )10)

40.7%11)

50%

ISIS 10-6

12) ( )

10-6

20~30%

PMT

2

WLSF 2

2.3WLSF


− � −


− � −

8

2

1) 6Li 10B ZnS

2) WLSF 1 ZnS/10B2O3

WLSF

3) WLSF 90WLSF 90

PMT WLSF

WLSF

4)

/ PMT

5)

Field Programmable Gate Array (FPGA)

3.

3.1 ZnS/10B2O3

6LiF6Li 4 10B

6Li 10B6Li + n 3H + + 4.78 MeV, 940 barn for thermal neutrons, 10B + n 7Li*+ + 2.792 MeV, (6%)


− � −


− � −

9

7Li*+ + 2.31 MeV, (94%) 3840 barn for thermal neutrons, 10B Q

(1)10B 6Li

7Li 4.2 m 2.3 m13) 6LiF 6.1 m 33.0 m

13) ZnS

Q 4.78 MeV10B

10B2O314) ZnS

ZnS:Ag H310BO3 1

600 ZnS H310BO3

1.5 : 1 JAEA ZnS/10B2O3 1

JAEA (50 x 50 mm2)

ZnS/10B2O3 ZnS

PMT15) PMT

3 Am-Be ISIS ZnS/6LiF16) (AST 0.4 mm) ZnS/10B2O3

ZnS/10B2O3

ZnS/10B2O3 0.3 mm ISIS ZnS/6LiF

0.1 mm

ZnS/10B2O3 ISIS ZnS/6LiF

ZnS/10B2O36Li

ISIS ZnS/6LiF

ZnS/10B2O3 ISIS ZnS/6LiF

ZnS/10B2O3

0.17 ~ 0.5 mm ZnS/10B2O3

2 140 mm x 140 mm ZnS/10B2O317)


− � −


− � −

10

(2)J-PARC (BL03)

0.5~8 Å

( )

ZnS/10B2O3 0.2 mm 0.3 mm 2

WLSF (64 X 64

) 4 Am-Be

JAEA ZnS/10B2O3 0.3 mm

0.2 mm 20~30%

ISIS 1~5 Å

0.2 mm

WLSF

0.4 mm

3.2(1)

WLSF PMT

WLSF

10 1 2

100 ppm

4

3.4~7% /

WLSF ZnS /WLSF WLSF /PMT

5


− � −


− � −

11

BCF-91A (a)

Y11 (c) ZnS (450 nm) BCF-92 (b)

BCF-92 Y11 BCF-92 ZnS18) Y11 (BCF91A) BCF- 92

( )

0.5 mm

(2) WLSF 1

WLSF

WLSF

Y11 ( 0.5 mm)

50 160 ppm 6

100~160 ppm

100~160 ppm

WLSF 160 ppm

(3)7 WLS 90

0.5 mm Y11 5~1000 mm LED

8

20 mm

10 mm 5 mm

80%

Y11 WLSF 90 1

9 11

90 73

10


− � −


− � −

12

30%

3.3512 PMT PMT 1 mm

1 30 mm x 30 mm x 45 mm( )

64 PMT PMT(H7546) 8

PMT 107 16

PMT(H8711) 19) 32

3 H8711 H7546 H7546 1

2 x 2 mm2 20 PMT

1 mm 1.5%20) PMT

107 PMT

(1) PMTH7546 PMT -950 V 2 x 106 20)

PMT

12 3

12 2.4 : 2.4 : 2.4 : 1 : 1 : : 1 : 1.2

PMT PMT

ZnS 10

1 WLSF (64 ) H7546

H8711( ) H7546

H8711 H7546 H8711

PMT

PMT

H7546 PMT

(2) (UBA) PMT2007 10

PMT(Ultra

Bialkali photomultiplier, UBA-PMT) 11 21)


− � −


− � −

13

WLSF 500 nm 16% 20% 1.3

UBA-PMT 2

(3)UBA H8711MOD(16

PMT) UBA

H8711MOD

4 x 4 mm2 H7546 4 2

mm WLSF 11 H7546 (20%) 11

WLSF WLSF LED

12 PMT 6

UBA BA-PMT 1.3~3.1%

0.1% %

PMT

UBA-PMT BA-PMT 1.2~1.8

PMT 3% BA-PMT

UBA-PMT

(4)UBA-PMT BA-PMT BA

UBA-PMT 2 -800 V 0.03 0.07

nA 1.4 4.8 nA UBA-PMT BA-PMT

UBA-PMT

PMT

X,Y

UBA-PMT PMT

13 1 WLSF (64 ) PMT BA-PMT

UBA-PMT

UBA-PMT BA-PMT

2 PMT (

) 104 cps/cm2

13 x 13 cm2 10-2 cps

2 UBA-PMT


− � −


− � −

14

(5)UBA BA-PMT 14

UBA-PMT BA-PMT 1.3

PMT

3.4 /PMT 1

PMT

mV ns 1

512

/

/

(1)16

PMT ( >100MHz)

10~40 WLSF 1 64

PMT(H7546) 252Cf

15 40

60 ( 600 MHz)

32 / ( 4 )

IC(THS3201 LMH6703) 2

/

16 40 mV

PMT -950V

(2) 32 /

(512 )


− �0 −


− �� −

15

IC

AD8001

220 MHz 4 32 /

7 (5 W/ 1 80 W/16 )

100 mm X 160 mm 17 /

30 mV

16 /

16 / 5

3.5

ToF

X Y 256 Low Voltage Differential Signaling (LVDS)

FPGA

FPGA 100 MHz 5 ns PMT

1 FPGA

1~4

ZnS

( )

( 18) X Y

PMT

2 FPGA

ToF

LVDS 19

1 X Y 8 ToF 12

DAQ ( 100 )

DAQ

6 30 cm x

15 cm x 25 cm ( )


− �0 −


− �� −

16

3.6 ToFToF ToF

ToF J-PARC T0

ToF 7 VME

1 1 FPGA 2GB (1GB X2) DRAM 16 MB SDRAM

FPGA

256 ch X 256 ch 4096

26 bit

T0 VME

4.

WLSF 2

820 2 1 m

J-PARC/MLF

2

30

177 cm2 13.3 cm X 13.3 cm

1 mm

69

: 10-6 (60Co )

16 cm X 16 cm X 30 cm

5 kg

5. ISIS

WLSF 2

ISIS

2

ROTAX 22) 15.74 m

0.6~5.2 Å 106


− �� −


− �� −

17

n/s/cm2

5.11 mm Cd

PMT-850 / 40 mV

1 21 (a)

ToF (b) 1( 1 s ) (a)

21 (b)

2 mm 1 mm

5.2 ToFToF

ToF 21(a) ToF 22

1 1.5 2 4 s

ToF ( 2 s23))

ISIS 1.5~1.8 Å ToF

5.32 Ni ( 6

mm) 9 ROTAX 2

2 90 (detector 1) 45 (detector 2)

65, 140 mm 23 ToF

1

24 ToF 2 ToF( )

Ni ToF

25

ToF

Ni ToF 2


− �� −


− �� −

18

6.

J-PARC/MLF 2

2

ISIS

2

JRR-3 CHOP

J-PARC

1) J-PARC/MLF BL03: < http://j-parc.jp/MatLife/ja/instrumentation/bl03/bl03.html>

2) D.P. Hutchinson, et al., Proc. SPIE 3769 (1999) p.88.

3) A. Gorin, et al., Nucl. Instrum. and Meth. A 479 (2002) p.456.

4) K. Sakai, et al., Nucl. Instrum. and Meth. A 529 (2004) p.301.

5) M. Katagiri et al., Nucl. Instrum. and Meth. A 529 (2004) p.325.

6) for example, SAINT-GOBAIN, Optical Scintillating Fibers catalogue.

7) A. Menzione, Proc. 2nd Int. Conf. on Calorimetry in High Energy Physics, Capri, 1991

(World Scientific, Singapore, 1992) p.131.

8) ATLAS TileCal, E. Mazzoni, Nucl. Instrum. and Meth. A 409 (1998) p.601.

9) K. Kuroda, et al., Nucl. Instrum. and Meth. A 430 (1999) p.311.

10) N.J.Rhodes, et al., Nucl. Instrum. and Meth. A 392 (1997) p.315.

11) M. Katagiri, et al., Nucl. Instrum. and Meth. A 529 (2004) p.274.

12) N.J.Rhodes, Private communication

13) Calculation with SRIM code, < http://www.srim.org/ >

14) T. Kojima et al., Nucl. Instrum. and Meth. A 529 (2004) p.325.


− �� −


− �� −

19

15) T. Nakamura et al., IEEE NSS 2008, to be published in Conference Record.

16) Applied Scintillation Technologies : < http://www.appscintech.com/>

17) N. Tsutsui, presented at 1st International Symposium on Pulsed Neutron and Muon

Sciences (IPS08), Mito, Ibaraki, Japan, 5 – 7 March 2008

18) M. Katagiri , Japanese Patent pending

19) Hamamatsu photonics, Multianode photomultiplier tube assembly H8711 catalogue, P2.

20) Hamamatsu photonics, Multianode photomultiplier tube assembly H7546 catalogue, P2.

21) Hamamatsu photonics, Ultra Bialkali photomultiplier catalogue, P11.

22) ISIS ROTAX < http://www.isis.rl.ac.uk/excitations/rotax/ >

23) T. Hosoya, et al., presented at 1st International Symposium on Pulsed Neutron and

Muon Sciences (IPS08), Mito, Ibaraki, Japan, 5 – 7 March 2008, to be published in NIMA.


− �� −


− �� −

20

Fig. 1: A schematic view of a typical neutron detector using a ZnS/6LiF scintillator and wavelength-shifting fibres.

Fig. 2: A schematic view of a two-dimensional neutron detector system using a neutron-sensitive scintillator and wavelength-shifting fibres. This system comprised of 256 fibres in both axis.

NeutronsZnS/6LiFscintillator

WLSF

Scintillation light

Reemitted light

NeutronsZnS/6LiFscintillator

WLSF

Scintillation light

Reemitted light

WLS fibers for Y axis

ZnS-type ScintillatorNeutrons

64 ch PMT x 4

Photon counting signal for Y axis

Scintillator

32 ch amp./discri. x 8

WLS fibers for X axis

Photon counting signal for X axis

64 ch PMT x 4


Image signal processing module

WLS fibers for Y axis

ZnS-type ScintillatorNeutrons

64 ch PMT x 4

Photon counting signal for Y axis

ScintillatorScintillator


WLS fibers for X axis

Photon counting signal for X axis

64 ch PMT x 4


Image signal processing module


− �� −


− �� −

21

Photo 1: A ZnS:Ag/10B2O3 scintillator made in house (50 mm x 50 mm).

Fig. 3: Pulse height spectra of a developed ZnS:Ag/10B2O3 and a standard ZnS/6LiF scintillator manufactured by AST Co. The scintillators were installed in an ENGIN-X type light reflector grid to collect scintillation light efficiently from the both sides of the scintillator15).

0

200

400

600

800

1000

0 50 100 150 200

Pulse height, ch

Cou

nts

/ 500

s

.

ZnS/LiF

ZnS/B_2O_3


− �� −


− �� −

22

Photo 2: Large size ZnS:Ag/10B2O3 scintillators manufactured by Chichibufuji Co. The size of the scintillators measured 14 cm x 14 cm. The thickness of the scintillator was 0.175 mm (left) and 0.375 mm (right).

Fig. 4: Neutron counts measured with a 2-d test detector equipped with a 0.2 or 0.3 mm-thick ZnS/10B2O3 scintillator.

0

100

200

50 70 90 110 130 150 170Threshold voltage, mV

Neu

tron

coun

ts in

cps

0.2 mm0.3 mm

Scintillator area : 32 x 32 mm2

ZnS/10B2O3 scintillator

Scintillator thickness


− �� −


− �� −

23

(b) BCF-92

0.0

0.2

0.4

0.6

0.8

1.0

1.2

300 400 500 600 700Wavelength, Å

Rel

ativ

e in

tens

ity, a

.u.

. Absorption

Emission

ZnS scintillation light

PMTsensitivity

Fig. 5: Light absorption/reemission spectra of a ZnS/6LiF scintillator, WLSF and a photocathode sensitivities of a bialkali PMT.

(a) BCF-91A

0.0

0.2

0.4

0.6

0.8

1.0

1.2

300 400 500 600 700Wavelength, Å

Rel

ativ

e in

tens

ity, a

.u.

. Absorption

Emission


PMTsensitivity

(c) Y11

0.0

0.2

0.4

0.6

0.8

1.0

1.2

300 400 500 600 700Wavelength, Å

Rel

ativ

e in

tens

ity, a

.u.

.

Absorption

Emission


PMTsensitivity


− �� −


− �� −

24

Fig.6: Light output of a Y11 WLSF of front and back fibres in a 2-d detector as a function of dye content. The Y11 fibres had square-shape with a side length of 0.5 mm.

Fig. 7: A schematic view of a scintillator/fibre head in a 2-d detector.

Wavelength shift ing fibe rsfor Y-axis readout

64 ch Multi-anodePhotomultiplier

Wave length shifting fibe rsfor X-axis readout

Fiber part bent in 90 degree

ZnS:Ag/ B2O3scintillator sheet

Neutrons ZnS:Ag/ B2O3scintillator sheet

Wavelength shift ing fibe rsfor Y-axis readoutWavelength shift ing fibe rsfor Y-axis readout

64 ch Multi-anodePhotomultiplier64 ch Multi-anodePhotomultiplier

Wave length shifting fibe rsfor X-axis readoutWave length shifting fibe rsfor X-axis readout

Fiber part bent in 90 degreeFiber part bent in 90 degree

ZnS:Ag/ B2O3scintillator sheetZnS:Ag/ B2O3scintillator sheet

NeutronsNeutrons ZnS:Ag/ B2O3scintillator sheetZnS:Ag/ B2O3scintillator sheet

0

0.2

0.4

0.6

0.8

0 100 200 300 400

Dye content in a 1/2-mm square fibre, ppm

Ligh

t out

put (

a.u.

)

I_f, simulationI_b, simulationexp. dataexp. dataexp. dataexp. data

Y11, Kuraray1/2-mm square fibres

front fibres

back fibres


− �0 −


− �� −

25

Fig. 8: Light transmission of round-shaped Y11 fibres as a function of bending radius. A diameter of a fibre was 0.5 mm. Four of Y11 fibres with multiclad were tested.

Fig. 9: Light transmission of square-shaped Y11 fibres with 90-degree bending.

0

1

2

3

4

5

6

0.62 0.66 0.7 0.74 0.78

Sam

ples

Transmissivity

0.6

0.7

0.8

0.9

1.0

1.1

0 5 10 15 20 25 30

Bending radius, mm

Nor

mal

ized

ligh

t out

put


− �0 −


− �� −

26

Photo 3: Multianode photomultipliers, H8711 (16 ch.) and H7546 (64 ch.), manufactured by Hamamatsu Co.

Fig. 10: Neutron counts measured with a 1-d WLSF test detector equipped with a H8711 or H7546 PMTs.

H8711

H7546

H8711

H7546

0

100

200

300

400

500

600

800 850 900 950 1000 1050High voltage, V

Neu

tron

cou

nts,

cps

H7546 with modified resistive chain

H8711 (16 ch, standard)

PMT


− �� −


− �� −

27

Fig. 11: A quantum efficiency of an ultra bialkali PMT manufactured by Hamamatsu Co21).

Fig. 12: Light cross talk between pixels on a PMT window in a bialkali (BA) PMT (a) and ultra bialkali (UBA) PMT (b). The light cross talk was defined as a ratio of a signal height relative to a signal in a center pixel (light incident pixel).

0.12.00.2

1.41001.3

0.42.20.3

0.12.00.2

1.41001.3

0.42.20.3

0.12.40.4

2.61001.4

0.33.10.4

0.12.40.4

2.61001.4

0.33.10.4

(a) BA-PM T (b) UBA-PM T


− �� −


− �� −

28

Fig. 13: Background counts measured with a 1-d WLSF test detector with a BA or UBA PMT.

Fig. 14: Neutron counts measured with a 2-d WLSF test detector with a BA or UBA PMT.

1.E-05

1.E-04

1.E-03

50 100 150 200 250

Threshold voltage, mV

Back

grou

nd c

ount

s (1

/s/c

m^2

)

BA-PMTUBA-PMT

0

50

100

150

200

250

0 50 100 150 200

Threshold voltage, mV

Neu

tron

coun

ts, c

ps

UBA-PMT

BA-PMT


− �� −


− �� −

29

Fig. 15: Neutron counts measured with a 2-d WLSF test detector with a preliminary amplifier board. The gain of the amplifier was variable from 10 to 40.

Photo 4: 32 channel amplifier/discriminator boards. A test board (left) and a prototype board (right).

0

1

2

3

4

5

6

7

8

0 10 20 30 40 50 60 70 80

x10 no14

x20 no20

x30 no15

x40 no11

Cou

ntin

g ra

te, c

ps

Discrimination level, mV

18 cm 16 cm

12 c

m 10 cm

18 cm 16 cm

12 c

m 10 cm


− �� −


− �� −

30

Fig. 16: Neutron counts measured with a 2-d WLSF test detector equipped with a 32-channel test amplifier/discriminator board.

Fig. 17: Pulse height spectrum of photons measured a prototype 32-channel amplifier/discriminator board.

0

20

40

60

80

100

0 0.1 0.2

Cou

nts

Peak voltage, V

AD8001Gain : x100


− �� −


− �� −

31

Photo 5: A prototype mini power crate for amplifier/discriminator boards.

Fig. 18: A pattern matching method employed in a signal processing and encoder module to determine a position of an incident neutron.

(a) F ront view (b) Rear view

20 cm

18cm

15 cm


20 cm

18cm

15 cm

(b) Rear view

20 cm

18cm

15 cm

Finding position

One

Two

Three

Four

A number oflit fibres

Determined position

Two of three

Three of four

Three of four


Determined position

Finding position

One

Two

Three

Four


Determined position

One

Two

Three

Four


Determined position

Two of three

Three of four

Three of four


Determined position

Two of three

Three of four

Three of four


Determined position


− �� −


− �� −

32

Photo 6: A signal processing and encoder circuit module.

Fig. 19: A data flow and data bit structure of the signal processing and encoder module.

Condition Parallel dataoutput

Analysisstatus

4bit4bitline

To Data readout module

Condition Parallel dataoutput

Analysisstatus

4bit4bitline

To Data readout module

LVDS output connector(To TOF data acquisition module)


30 cm

16 LVDS input connectors(From Amp. & discriminator)

25cm

15cm

LVDS output connector(To TOF data acquisition module)LVDS output connector(To TOF data acquisition module)


30 cm


25cm

15cm

30 cm


25cm

15cm


− �� −


− �� −

33

Photo 7: A time of flight data acquisition circuit module

Photo 8: A prototype detector. A front view (a) and a rear view (b).

1 GB DRAM x 2 FPGA

16 M B SDRAM

1 GB DRAM x 2 FPGA

16 M B SDRAM

(a) F ront view (b) Rear view(a) F ront view (b) Rear view


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34

Fig. 20: A prototype 2-d WLSF detector system. A block diagram (a) and detector system (b).

Fig. 21: A collimated neutron beam measured with a prototype detector summed over whole time of flight. A 2-d image (a) and a sliced spectrum at the peak (b).

LVDS signal cable10 m

1m

1 2 3

6 5 4

A. High position resolution neutron imaging detector

Main computersystem

VME Power Supply

ETHER-NET

LVDS Cable(~10 m)

DataAcqui-sitionmodule

CPUModule

or(SiTCP)

Signal processingmodule with FPGA

2 x 256 ch.amplifier &discriminator

Scintillator

Detector

WLS photon readout pack

B4C light fiber block

64 ch read out circuit

64 ch Multianode PMT

B. TOF data acquisition system


Main computersystem

VME Power Supply

ETHER-NET

LVDS Cable(~10 m)


CPUModule

or(SiTCP)



Scintillator

Detector






LVDS signal cable10 m

1m

1 2 3

6 5 4


Main computersystem

VME Power Supply

ETHER-NET

LVDS Cable(~10 m)


CPUModule

or(SiTCP)



Scintillator

Detector







Main computersystem

VME Power Supply

ETHER-NET

LVDS Cable(~10 m)


CPUModule

or(SiTCP)



Scintillator

Detector






(a) 2-d image (b) 1-d spectrum

0

1000

2000

3000

4000

0 5 10 15 20 25Channel

Cou

nts,

a.u

.

DataGaussian fit

FWHM = 2.0 mm

(a) 2-d image (b) 1-d spectrum

0

1000

2000

3000

4000

0 5 10 15 20 25Channel

Cou

nts,

a.u

.

DataGaussian fit

FWHM = 2.0 mm


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35

Fig. 22: Time of flight spectra in the area of neutron count peak.

Photo. 9: Experimental setup in the ROTAX port at ISIS pulsed neutron source. Two prototype 2-d WLSF detectors were set up at the angle positions of 45 and 90 degree.

1

10

100

1000

0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000

Coun

t

Time of flight [us]

ISIS ROTAX, Direct beam with slit, 2008-3-12

1.0-us 2-4P coinc1.5-us 2-4P coinc2.0-us 2-4P coinc4.0-us 2-4P coinc

1

10

100

1000

0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000

Coun

t

Time of flight [us]

ISIS ROTAX, Direct beam with slit, 2008-3-12

1.0-us 2-4P coinc1.5-us 2-4P coinc2.0-us 2-4P coinc4.0-us 2-4P coinc

Detector 1Detector 2

Ni rod

Detector 1

Detector 2

neutron Detector 1Detector 2

Ni rod

Detector 1Detector 2

Ni rod

Detector 1

Detector 2

neutron

Detector 1

Detector 2

neutron


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36

Fig. 24: Scatter plot of neutron diffraction from a Ni rod sample.

Fig. 23: Diffraction images of Ni rod measured with a detector 1 and detector 2 at fixed time of flight.

(a) Detector 1 (b) Detector 2(a) Detector 1 (b) Detector 2

40

140

2

Wavelength (ToF)

40

140

2

Wavelength (ToF)


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37

Fig. 25: Time of flight spectra after time focusing correction.


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