Study on energy resolution improvement of pixelated CdZnTe detectors based on 3D position sensitivity

Abstract The pixelated cadmium zinc telluride (CZT) detector is extensively utilized in the domains of nuclear imaging and energy spectrum measurement due to its superior energy resolution and spatial accuracy. Nonetheless, the intrinsic charge transport characteristics of CZT material result in signal response distortion in the near-anode region, which constrains the enhancement of both energy resolution and detection efficiency. This study introduces a refined three-dimensional position resolution and energy spectrum calibration technique, employing a combination of finite element method (FEM) and Monte Carlo methods to reconstruct the accurate signal response of deposited energy. Furthermore, by examining the variation of induced charges between adjacent pixels, we facilitate the attainment of subpixel resolution within the detector. Additionally, based on the subpixel resolution technique, we assess the potential for energy spectrum calibration in the near-anode region. The results indicate that improving three-dimensional position resolution can mitigate the deterioration of energy resolution caused by the non-uniform electric and weighting fields in the near-anode area. Supported by compatible electronic readout systems, this method offers the potential to enhance the energy resolution and effective sensitive volume of pixelated CZT detectors.