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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 Development of Two-dimensional Scintillator Neutron Detector using Wavelength-shifting Fibres - Development of a Compact Detector for iBIX Instrument in J-PARC/MLF -

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

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  • 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

    JAEA-Research 2008-115

    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

    ����

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    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

    ����

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  • 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

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    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

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    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

    )

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    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

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    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%)

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    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 H310BO31.5 : 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/10B2O3ZnS/10B2O3 0.3 mm ISIS ZnS/6LiF

    0.1 mm

    ZnS/10B2O3 ISIS ZnS/6LiF

    ZnS/10B2O3 6Li

    ISIS ZnS/6LiF

    ZnS/10B2O3 ISIS ZnS/6LiF

    ZnS/10B2O3

    0.17 ~ 0.5 mm ZnS/10B2O32 140 mm x 140 mm ZnS/10B2O3 17)

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    (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

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    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

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    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)

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    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

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    (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 )

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    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 ( )

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    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

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    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

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    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.

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  • 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.

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    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

    32 ch amp./discri. x 8

    Image signal processing module

    WLS fibers for Y axis

    ZnS-type ScintillatorNeutrons

    64 ch PMT x 4

    Photon counting signal for Y axis

    ScintillatorScintillator

    32 ch amp./discri. x 8

    WLS fibers for X axis

    Photon counting signal for X axis

    64 ch PMT x 4

    32 ch amp./discri. x 8

    Image signal processing module

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    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

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    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

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    (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

    ZnS scintillation light

    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

    ZnS scintillation light

    PMTsensitivity

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    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

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    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

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    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

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    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

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    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

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    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

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    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

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    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

    (a) F ront view (b) Rear view

    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

    A number oflit fibres

    Determined position

    Finding position

    One

    Two

    Three

    Four

    A number oflit fibres

    Determined position

    One

    Two

    Three

    Four

    A number oflit fibres

    Determined position

    Two of three

    Three of four

    Three of four

    A number oflit fibres

    Determined position

    Two of three

    Three of four

    Three of four

    A number oflit fibres

    Determined position

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    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)

    (a) F ront view (b) Rear view

    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)

    (a) F ront view (b) Rear view

    30 cm

    16 LVDS input connectors(From Amp. & discriminator)

    25cm

    15cm

    30 cm

    16 LVDS input connectors(From Amp. & discriminator)

    25cm

    15cm

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    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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    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

    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

    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

    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

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

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