compton imaging with the porgamrays detector
DESCRIPTION
Compton imaging with the PorGamRays Detector. D S Judson. Imaging 2010, Stockholm, 8 th -11 th June 2010. Outline. PorGamRays project outline Detector description Spectroscopic performance GEANT simulations Experimental Compton imaging performance Summary. PorGamRays: Aims. - PowerPoint PPT PresentationTRANSCRIPT
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Compton imaging with thePorGamRays Detector
D S Judson
Imaging 2010, Stockholm, 8th-11th June 2010
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Outline
PorGamRays project outline
Detector description
Spectroscopic performance
GEANT simulations
Experimental Compton imaging performance
Summary
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PorGamRays: AimsPortable Gamma-Ray Spectrometer
The project aims to develop a gamma-ray spectrometer that is
Handheld and battery operated
Able to work at room temperature
Capable of providingIsotope identificationImaging
Potential applications for this sensor include:
decommissioning, security and
safety monitoring
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6 CZT detectors
Modular design
Energy range:
60 – 2000 keV
PorGamRays: Schematic
gamma
Pixelated CZT
ASICDaughter board
MotherboardLaptop
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PorGamRays: CZT detectors
Dimensions of 20 x 20 x 2 mm
Pixelated (10 x 10)
2 x 2 x 2 mm voxels
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PorGamRays: CZT detectors
Dimensions of 20 x 20 x 2 mm
Pixelated (10 x 10)
2 x 2 x 2 mm voxels
Detector wire bonded
to daughter board
Data read out through
custom built ASICs
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The PorGamRays demonstrator
Two CZT detectors
5 mm separation
Running from external
power supplies
NUCAM II ASICS [1]
Energy range of up to 350 keV
[1] P Seller et. al., IEEE Nuclear Symposium Conf. Rec., V6, 3786, ‘06
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Spectroscopic performance of CZT
At 60 keV (241Am), FWHM ~ 6 keV, noise ~ 20 keV
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Geant4 simulations
Simulated data used to evaluated the effects of the 20 keV noise level and 350 keV energy limit
Simulated two CZT detectors in PorGamRays configuration
Two different gamma-ray energies were used: 121 and 356 keV
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Geant4 simulations
121 keV γ-rays deposit little energy in the scatter detector
Scatterer
Absorber
Eγ (keV)0 20 40 60 80 100 120 140 160 180 200
Eγ (keV)
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Geant4 simulations
356 keV γ-rays deposit 140-220 keV in each detector
Scatterer
Absorber
0 50 100 150 200 250 300 350 400
Eγ (keV)
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Source located at
x = y = 100 mm
z = 40 mm
x (mm)
y (m
m)
FWHM ~ 20 mm
120
120
100
100
y (mm)
x (mm)
Compton images – 133Ba – 356 keV
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Compton images – 133Ba – 356 keV
x (mm)
y (m
m)
FWHM ~ 20 mm
Source located at
x = 105mm y = 115 mm
z = 40 mm
120
120
100
100
y (mm)
x (mm)
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Possible to resolve changes in source position of only a few mms
x position (mm)
x = 95 mm
x = 115 mm
Compton images – 133Ba – 356 keV
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Multi-spectral imaging
133Ba (356 keV) 57Co (121 keV)
x = 110, y = 120 mm x = 130 mm, y =85 mm
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Conclusions
A CZT based Compton camera has been developed
Energy resolution of ~ 10 % at 60 keV
Position resolution of ~ 20 mm FWHM has been demonstrated
Changes in position of ~ 10 mm can easily be resolved
Simultaneous measurement of 2 different source demonstrated
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CollaboratorsA J Boston1, P J Coleman-Smith2, D M Cullen3,
A Hardie4, L J Harkness1, L L Jones4, M Jones1,
I Lazarus2, P J Nolan1, V Pucknell2, S V Rigby1, D P Scraggs1,
P Seller4, J Simpson2, M Slee1, A Sweeney1
and the PorGamRays collaboration.
1 The University of Liverpool
2 STFC Daresbury Laboratory
3 The University of Manchester
4 STFC Rutherford Appleton Laboratory
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Funded jointly by the EPSRC and TSB