1. Compton imaging with the PorGamRays Detector D S Judson Imaging 2010, Stockholm, 8 th -11 th 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. 6 CZT detectors Modular design Energy range: 60 – 2000 keV PorGamRays: Schematic gamma Pixelated CZT ASIC Daughter board Motherboard Laptop

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 ( 241 Am), 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 Absorber Eγ (keV) 0 20 40 60 80 100 120 140 160 180 200 Eγ (keV)

11. 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)

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

13. x (mm) y (mm) FWHM ~ 20 mm Source located at x = 105mm y = 115 mm z = 40 mm 120 100 y (mm) x (mm)

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

15. Multi-spectral imaging 133 Ba (356 keV) 57 Co (121 keV) x = 110, y = 120 mmx = 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 Boston 1, P J Coleman-Smith 2, D M Cullen 3, A Hardie 4, L J Harkness 1, L L Jones 4, M Jones 1, I Lazarus 2, P J Nolan 1, V Pucknell 2, S V Rigby 1, D P Scraggs 1, P Seller 4, J Simpson 2, M Slee 1, A Sweeney 1 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