Simulation and experimental results on monolithic CdZnTe gamma-ray detectors

Monolithic CdZnTe detectors are promising for medical and small animal imaging because of a good energy resolution that allows both multi-drug diagnostic and scatter event rejection. Optimizations of electrode geometry and detector thickness are used to improve detection efficiency as well as energy resolution for various material transport properties, with the ULYSSE simulator. As an example, for a 5 mm thick detector with (mu tau)(e) = 3. 10(-3) cm(2)/V, a 1.8 mm pitch gives the best simulated energy resolution on the conventional spectrum at 122 keV. Nevertheless, even with an optimized detector, electronic correction methods contribute to reduce tailing. Correction using cathode and anode signals have been tested with HPBM CdZnTe and THM CdTe:Cl detectors. The appropriate method to correct energy seems to depend on material. This paper also presents experimental results on charge sharing and loss.