Investigation of the Imaging Polarization Effect Based on a Pixellated CdZnTe Detector

A pixel array CdZnTe imaging system, employing a 40×40×5 mm3 pixellated CdZnTe detector, is established. The imaging polarization effect in the CdZnTe pixellated detector for a collimated Cs137 Gamma source is investigated in detail. The experimental results for different irradiated fluxes indicate that excessive irradiated flux indeed causes central pixels to be shut off completely. The imaging performance of the polarized detector is severely degraded. Polarized detector counts are simultaneously reduced to one-third of the non-polarized detector counts. A theoretical model of potential distribution is also proposed by solving the Poisson equation and, in turn, the electric potential distortion for high irradiated flux is discussed by comparison with the experimental results.