Simulation and experimental results on monolithic CdZnTe gamma-ray detectors

Monolithic CdZnTe detectors are promising for medical and small animal imaging thanks to their good energy resolution that allows both multidrug diagnostics and scatter rejection. Using the ULYSSE simulator, electrode geometry and detector thickness are optimized to improve detection efficiency and energy resolution for various material transport properties. As an example, for a 5 mm thick detector with (mutau)_e=3times10^-3 cm²/V, a 1.8 mm electrode pitch gives the best-simulated energy resolution on the conventional spectrum at 122 keV. Once the electrode geometry and thickness are optimized, electronic correction methods are shown to further reduce spectrum tailing. Corrections using cathode and anode signals have been tested with the high pressure Bridgman method (HPBM) CdZnTe and THM CdTe:Cl detectors. The best method for electronic correction appears to depend on the material