Monte Carlo investigation of the charge sharing effects in 3-D position sensitive CdZnTe gamma ray spectrometers

Charge sharing effects in a 3-D position sensitive CdZnTe detector have been investigated by Monte Carlo simulations and experimental measurements. The charge sharing is mainly caused by the range of electrons, X-ray emission following by photoelectric interactions, and the diffusion of charge carrier electrons during their drift towards the anodes. A simple model has been developed to include the diffusion effect in the Monte Carlo simulation. Good agreement has been achieved for various irradiation and bias conditions. Based on our model simulations, a 1 mm optimal pixel size is recommended for future 1 cm thick CZT detectors for 662 keV gamma rays.