1. Compton Camera development for the imaging of high energy gamma rays 1 Martin Jones UNTF 2010 Salford – April 14 th 2010 Email: mj@ns.ph.liv.ac.uk Martin Jones – UNTF April 2010

2. Overview 2 Introduction to the Distinguish Project Compton Imaging Detectors Current work Summary Martin Jones – UNTF April 2010

3. The Distinguish project 3 Developing a highly specific detection and imaging system for the detection and quantification of narcotics and more notably, explosives. Current imaging systems are based on methods such as conventional X-ray imaging through to CT scanners which provide the user with a high level of shape and density information of objects contained within luggage/cargo. This method does not provide any nuclide identification. Industry has indicated a desire to deduce the composition of suspect objects using current novel imaging techniques. Martin Jones – UNTF April 2010

4. The Distinguish project 4 Explosives/narcotics contain combinations of the lighter elements Elements such as Oxygen, Carbon and Nitrogen which have characteristic gamma rays After neutron interrogation these characteristic gamma rays will be emitted An illustration of the chemical difference between Dynamite (a) and TNT (b) (a)(b) Martin Jones – UNTF April 2010 Oxygen - 6.13MeV, Nitrogen - 5.11MeV, 2.31MeV, 1.64MeV, Carbon – 4.43MeV

5. Compton Imaging 5 Projected Cones Location of point source The Compton imaging technique is to be used to localise the source of gamma rays Cone reconstruction method defines that the area of maximum overlap is attributed to source location Scatter detector – good energy resolution, position dependence Absorber detector - high stopping power and position dependence Looking at energies in the range of 0.5-5.0MeV Martin Jones – UNTF April 2010

6. Gamma-ray detection and imaging 6 The scatter detector Planar HPGe detector 60 x 60 x 20mm active volume 12 x 12, 5mm wide orthogonal strips position resolution – in order of a cubic mm Energy resolution (1.53keV @ 122keV) Martin Jones – UNTF April 2010

7. Gamma-ray detection and imaging 7 The absorber detector 64 pixel CsI detector (8 x 8) Photomultiplier – 64 pixels (8 x 8) 64 individual preamps High stopping power 51.6 x 51.6 x 50mm active volume with 4.48 x 4.48 x 50mm pixels Martin Jones – UNTF April 2010

8. Geant4 validation 8 Martin Jones – UNTF April 2010 L.J. Harkness, et al., Nucl. Instr. and Meth. A (2009)

9. Current progress – Simulations 9 Germanium - Germanium configuration 5cm source – detector and detector – detector separation Germanium - Caesium Iodide configuration (5cm, 2cm and 10cm CsI simulations) 5cm source – detector and detector – detector separation Martin Jones – UNTF April 2010

10. Simulations 10 Martin Jones – UNTF April 2010

11. Simulations 11 Martin Jones – UNTF April 2010

12. Simulations 12 Martin Jones – UNTF April 2010

13. Simulations 13 Martin Jones – UNTF April 2010

14. Klein-Nishina 14 Martin Jones – UNTF April 2010

15. Klein-Nishina 15 Martin Jones – UNTF April 2010

16. Simulated detector ‘maps’ 16 Martin Jones – UNTF April 2010

17. The next step 17 1.Generate images using current Compton reconstruction code that has been developed in Liverpool. 2. Assess image quality. (Efficiency and image resolution). 3. Add in other factors to the simulations such as energy resolution and position resolution. 4. Implement all of the above experimentally. Martin Jones – UNTF April 2010

18. The next step. 18 Full detector characterisation to be complete. Detector is on scanning table Will be performed using X-Y scanning table. Move in increments of 1mm. Collimated beam of 122keV gamma-rays. (Co-57). Quantify the uniformity of each pixel. Martin Jones – UNTF April 2010

19. The next step. 19 Martin Jones – UNTF April 2010

20. Summary. 20 Energies of interest 0.5-5.0MeV. Geometry decided based on simulated efficiency. Initial simulated images. - Image quality/position resolution. Raster scan of CsI detector using Co 57 Aim to complete imaging with Ge/Ge and Ge/CsI in Compton camera mode. Martin Jones – UNTF April 2010

21. M.P.Jones 1, A.J. Boston 1, H.C Boston 1, R.J. Cooper 1 M.R. Dimmock 1, L.P. Gaffney 1, A.N. Grint 1, L.J. Harkness 1, D. Judson 1, P.J. Nolan 1, D.C. Oxley 1, B. Pietras 1, A. Sweeney 1, M.J. Joyce 2, R.O. Mackin 2, M.D. Aspinall 2, A.J. Peyton 3, R.G. Silfhout 3 1 Department of Physics, University of Liverpool, UK 2 Department of Engineering, Lancaster University, UK 3 School of Electronic and Electrical Engineering, The University of Manchester, UK 21 Martin Jones – UNTF April 2010

22. Martin Jones – Summer School Leicester 2009 22 Further simulations. No significant change in the number of 1-1 interactions when comparing 5cm and 10cm thick detector. No depth of interaction information possible. 5cm thick detector being used to reduce angular uncertainty.