Study of Charge Sharing on CdTeCZT Detectors with Segmented Electrodes

The factors degrading the performance of CdTeCdZnTe detectors are the interaction depth dependence of signal induced by ionizing radiation, and for segmented electrode devices the charge sharing between adjacent pixels or strips. To evaluate the influence of the latter effect on the overall response of position sensitive spectrometers, we have performed several measurements on a CZT multipixel and a CdTe microstrip detector. A parallel numerical study has been carried out in order to evaluate charge-sharing between adjacent strips as a function of various geometrical and electronics parameters. The microstrip anode is composed of 15 strips, each 18 times 0.15 times 2 mm³, with a pitch of 0.5 mm, while the pixel size of the 4times4 channel CZT detector is 1.8 times 1.8 times 5 mm³ (2 mm pitch). Both tested detectors are equipped with a single cathode. We report laboratory measurements, compared with the simulation results, of the double events (events that induce the signal on two adjacent strips or pixels), as a function of the photon energy, at different values of the coincidence time, for the same low energy threshold and at various anode bias.