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Compton imaging with the PorGamRays Detector

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.

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Compton imaging with the PorGamRays Detector

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  1. Compton imaging with thePorGamRays Detector D S Judson Imaging 2010, Stockholm, 8th-11th June 2010

  2. Outline • PorGamRays project outline • Detector description • Spectroscopic performance • GEANT simulations • Experimental Compton imaging performance • Summary

  3. PorGamRays: Aims Portable 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 providing • Isotope identification • Imaging Potential applications for this sensor include: decommissioning, security and safety monitoring

  4. PorGamRays: Schematic Laptop Motherboard • 6 CZT detectors • Modular design • Energy range: 60 – 2000 keV gamma Pixelated CZT Daughter board ASIC

  5. PorGamRays: CZT detectors • Dimensions of 20 x 20 x 2 mm • Pixelated (10 x 10) • 2 x 2 x 2 mm voxels

  6. 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

  7. 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

  8. Spectroscopic performance of CZT • At 60 keV (241Am), FWHM ~ 6 keV, noise ~ 20 keV

  9. 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

  10. Geant4 simulations 121 keV γ-rays deposit little energy in the scatter detector Scatterer 0 20 40 60 80 100 120 140 160 180 200 Eγ (keV) Eγ (keV) Absorber

  11. Geant4 simulations 356 keV γ-rays deposit 140-220 keV in each detector Scatterer 0 50 100 150 200 250 300 350 400 Eγ (keV) Absorber

  12. Compton images – 133Ba – 356 keV Source located at x = y = 100 mm z = 40 mm x (mm) y (mm) 100 120 120 y (mm) x (mm) 100 FWHM ~ 20 mm

  13. Compton images – 133Ba – 356 keV Source located at x = 105mm y = 115 mm z = 40 mm x (mm) y (mm) 100 120 120 y (mm) x (mm) 100 FWHM ~ 20 mm

  14. Compton images – 133Ba – 356 keV Possible to resolve changes in source position of only a few mms x = 115 mm x = 95 mm x position (mm)

  15. Multi-spectral imaging 133Ba (356 keV) 57Co (121 keV) x = 110, y = 120 mm x = 130 mm, y =85 mm

  16. 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

  17. Collaborators A 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

  18. Funded jointly by the EPSRC and TSB

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