Anger Camera for neutrons

Anger Camera for neutrons

F. A. F. Fraga, L. M. S. Margato ,S. T. G. Fetal, M. M. F. R. Fraga, A. Morozov, L. Pereira, R. Ferreira Marques, P. Mendes, J. P. Rodrigues

LIP Coimbra, Universidade de Coimbra

FP6 NMI3 JRA2 RII3-CT-2003-505925 ended 2008

MILAND – development of thermal neutron detectors•Would increase knowledge about neutron detectors, but should have a deliverable working detector prototype with a firm and clear specification

• Partners and Observers• P1 CCLRC N. Rhodes (UK) T3, T6, T7• P2 GKSS R. Kampmann (Germany) T1, T4, T5, T6, T7• P3 BNC L. Rosta (Hungary) T1, T5, T6, T7• P4 ILL B. Guerard (France) T1, T2, T3, T4, T5, T6, T7 coordinator• P5 LLB C. Fermon (France) T2, T4, T6, T7• P6 FRM-II K. Zeitelhack (Germany) T1, T2, T4, T6, T7• P7 LIP F. Fraga (Portugal) T2, T3, T6, T7

ObserversEFO1 BNL G. Smith (USA)

• EFO2 SNSR. Cooper (USA) • EFO3 TU H. Takahashi (Japan) • EFO4 RAL J. Mir (UK)• EFO5 BNL R. Krueger TU Delft (NL)

•32 x 32 cm2 detector•1 mm resolution (FWHM) res/length = 3x10-4

•1 MHz global count rate•100 kHz / mm2 local (peak) count rate•Gamma background rejection 10-8

•50% efficient at 1.8Å•parallax free•Cost is critical

Integrated Infrastructure Initiative for Neutron Scattering and Muon Spectroscopy

http://jra2.neutron-eu.net/jra2/j2_partners/j2_p1_-_cclrc

http://jra2.neutron-eu.net/jra2/j2_partners/j2_p2_gkss

http://jra2.neutron-eu.net/jra2/j2_partners/j2_p3_bnc

http://jra2.neutron-eu.net/jra2/j2_partners/j2_p4_ill

Neutron Detectors nuclear reactions to convert neutrons

• n + 3He 3H + 1H + 0.764 MeV Gaseous detectors (CF4, prop.)

• n + 6Li 4He + 3H + 4.79 MeV Scintillators• n + 10B 7Li* + 4He7Li + 4He + 0.48 MeV +2.3 MeV

(93%) 7Li + 4He +2.8 MeV ( 7%)

• n + 155Gd Gd* -ray spectrum conversion electron spectrum • n + 157Gd Gd* -ray spectrum conversion electron spectrum • n + 235U fission fragments + ~160 MeV • n + 239Pu fission fragments + ~160 MeV

Scintillators for Neutron Detectors

CWE van Eijk, NIM A529(2004)260-267

Gaseous detectors

n + 3He 3H + 1H + 0.764 MeV

CF4 should be added to control the range -3 bar for 1mm FWHM

• CF4 is a good scintillator, but only a few primary photons• Secondary scintillation ~.3 photon per secondary electron

200 300 400 500 600 700 800 9000

200

400

600

800

I norm (a

.u.)

(nm)

CF3

*

CF4+*, CF3

+*

PMT 2

10mm

35m

m

Boron Mask

Neutron Beam

Quartz Window

anodes

PMT 3

AQUISISITION CARDS: Acqiris, CC103

PMT 1 PMT 4

PC

trigger (from anodes or cathodes)

Drift electrode

n

T

p

Scintillation Anger camera

PMT

Transparent window

MSGC

PMT base

gas

Neutron window

PMT

PMT base

New MSGC Batch

NMI3 Meeting, CORSICA, 25-28th June 2008

Remarks

• Cathodes width of the new set of microstrips is more or less half of the older ones (181m vs. 398 m) and the anodes seems to be larger.

• To achieve the same charge gain the new microstrip needed a higher anode voltage than the older one.

• For instance, at 1 bar of CF4, to reach a gain of G ~103 we should apply a voltage of Va~1900V, something like 840V more than in the older microstrip (Va=1060V).

• Taking off the drawbacks linked to a higher voltage, the light yield obtained with the new microstrip (for G ~103 ) is ~ 0.263 ph/sec-e, about 4.5 times higher than the light yield in the older one (~0.045 ph/sec-e).

• This MSGCs batch are unable to operate above 1 bar CF4 (discharges).

Charge gain and light/charge versus anode voltage 15, 20 and 30µm anodes

CF4 (1bar)

CF 4 (1bar)

1.0E+01

1.0E+02

1.0E+03

1.0E+04

500 700 900 1100 1300 1500

Va (V)

Gai

n

15 micron anodes20 micron anodes30 micron anodes

CF 4 (1bar)

0

5

10

15

20

500 700 900 1100 1300 1500

Va (V)

S PM

T /

Qan

ode

15 micron anodes

20 micron anodes

30 micron anodes

New MSGC Batch


Charge and light measurements

Charge gain versus anode voltage Number of emitted photons per

secondary electron

CF 4 (1bar); V d =-700V

1.0E+01

1.0E+02

1.0E+03

1.0E+04

800 1000 1200 1400 1600 1800 2000

V anode (V)

Gai

n

15 micronNew Microstrip - April 2008

CF 4 (1bar)

0.00

0.10

0.20

0.30

0.40

0.50

1.0E+02 1.0E+03 1.0E+04Gain

Em

itte

d P

hoto

ns /

s.e.

15 micron

New Microstrip - April 2008

MSGC ILL6C at High pressure


Measurements at 3 bar CF4

CF 4 (3bar)

0.00

0.10

0.20

0.30

0.40

0.50

1.0E+02 1.0E+03 1.0E+04Gain

Em

itte

d P

hoto

ns /

s.e

ILL6C - Nº1ILL6C - Nº2LLB - 15 micron

CF4 -3bar

1.0E+02

1.0E+03

1.0E+04

1400 1600 1800 2000V anode (V)

Gai

n

ILL6C - Nº2ILL6C - Nº3LLB - 15 micron


secondary electron

Simulations F.Fraga, Hamburg meeting

GSPC details

GSPC in position at the ILL beamAquisition system by Acquiris and E. Shooneveld

2D position images Vanode = 1360, 1550 1650 and 1850V

Mask_1650_3.eve: Va=1650 V; VPMT= 800 V.

fwhm (yy)~1.63 mm

fwhm (xx)~1.68 mm

Mask_1650_3.eve: Va=1650 V; VPMT= 800 V

FHWM center peak 1.68 mm

FHWM center peak 1.63 mm

FWHM resolution versus Vanode

0.00

0.50

1.00

1.50

2.00

2.50

3.00

1300 1500 1700 1900

Vanode (V)

peak

FW

HM

(m

m)

(XX)

(YY)

•For the best safe conditions (Vanode =1850 V; VPMT= 800 V) the intrinsic resolution is 1.1mm after we deconvolute the beam width

Detector uniformity (1850V)

Typical PMT signals

High amplitude – good discrimination

Very fast signals – risetime ~20ns

Transparent electrode MSGC

• Manufactured at the Tokyo University and supplied by Hiroyuki Takahashi

• 90% ITO electrode transparency

• The transparent window can be the active element

• Multigrid approach proposed –it has the advantage of a very high local count rate.

ITO M - MSGC


Photographs

ITO M - MSGC


Experimental Setup

Drift length = 10 mm

Distance between microstrip and PMT = 34.8mm

ITO M - MSGC


Ar+5%CF4 (1atm, 100cc/min.) and CF4 (1atm, 100cc/min.)

ITO M - MSGC

1.0E+02

1.0E+03

1.0E+04

1.0E+05

500 700 900 1100V anode (V)

Gai

n

Ar+5%CF4 (Vg1=400V)

100%CF4 (Vg1=600V)

ITO - Microstrip

0.00

0.10

0.20

0.30

0.40

1.0E+02 1.0E+03 1.0E+04Gain

Nº o

f em

itte

d ph

oton

s / s

.e Ar+5%CF4 (Vg1=400V)

100%CF4 (Vg1=600V)


secondary electron

ITO M - MSGC


Effect of GRID potential (Vg) on Gain and light yield

ITO M - MSGC: 100%CF 4 , Vd=-500V

1.0E+02

1.0E+03

1.0E+04

1.0E+05

600 800 1000 1200V anode (V)

Gai

n

Vg1=200V

Vg1=400V

Vg1=600V

vg1=800V

ITO - Microstrip: 100%CF 4 , Vd=-500V

0.00

0.10

0.20

0.30

0.40

1.0E+02 1.0E+03 1.0E+04 1.0E+05

GainN

º of e

mit

ted

phot

ons

/ s.e Vg1=200V

Vg1=400V

Vg1=600V

Vg1=800V

Charge gain versus anode voltage for several GRID voltages

Number of emitted photons per secondary electron

ITO M - MSGC


Example of typical signal taken directly from the PMT Hamamatsu R1387 (RL=50 ): 55Fe (5.9keV) X-ray source

•100%CF4 (1atm)

•Vdrift= -500V, Vcathode=0

•Vanode=990V Vg1= 600V

•VPMT=-1000V

60ns

100 mV

MSGC ILL6C at High pressure


Measurements at 3, 4 and 5 bar CF4

CF4 - 3, 4 & 5 bar

1.0E+02

1.0E+03

1.0E+04

1400 1900 2400 2900V anode (V)

Gai

n

LLB - 15mic.-3 bar ILL6C - 3 barILL6C - 4 barILL6C - 5 bar

CF 4 - 3, 4 & 5 bar

0.00

0.10

0.20

0.30

0.40

0.50

1.0E+02 1.0E+03 1.0E+04Gain

Em

itte

d P

hoto

ns /

s.e

LLB - 15mic. - 3barILL6C - 3 barILL6C - 4 barILL6C - 5 bar


secondary electron

2009-2011 FP7 WP22CP-CSA_INFRA-2008-1.1.1 Number 226507-NMI3

• Development of new thermal neutron detector technologies based on Gaseous Scintillation Proportional Counters (GSPC) • Explore their potential to overcome the limitations in light output and rate capability of existing scintillation detectors • Investigate their potential as high resolution detectors for Reflectometry or time resolved SANS. • Built and study small scalable prototypes

http://detectors.neutron-eu.net/Detectors

The new family members, born in Munich two months ago!

We will go on studying the scintillation and the PMT readout

The good not so good new

• European Spallation Source (ESS) went to Lund in Sweden

The bad new

• 3He crisis

Documents

Anger Camera for neutrons