γ-ray energy spectrum response tailing in CdZnTe detector

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 2022-08, Vol.1037, p.166922, Article 166922
• Main Authors: Li, Linxiang, Huang, Guangwei, Xi, Shanxue, Zhang, Siyuan, Zhou, Chunzhi, Liu, Dahai, Wang, Zungang, Zeng, Guoqiang, Yang, Xiaofeng
• Format: Article
• Language: English
• Subjects: Charge collection efficiency; CZT detector; Energy spectrum response; Finite element analysis; Monte Carlo simulation
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2022.166922

Affected by the characteristics of carrier transport, the γ-ray energy spectrum of the cadmium zinc telluride (CZT) detector usually has a low-energy tail phenomenon The traditional γ -ray energy spectrum response simulation model is mainly aimed at detectors with a uniform internal electric field, not suitable for non-uniform internal electric fields, and cannot accurately characterize the low-energy tailing phenomenon of the γ -ray energy spectrum of CZT detectors. In this study, for the quasi-hemispherical and coplanar-grid CZT detectors, the Geant4 program was used to establish the energy deposition model, and the γ-ray energy deposition and the carrier distribution in the two detectors were obtained. On this basis, the finite element analysis method was used to construct the internal electric field of the two detectors, and the charge collection efficiency model is established according to the transport law of carriers in the detectors. Finally, the above model was used to simulate the γ energy spectrum response of the four nuclides 241Am, 133Ba, 137Cs, and 60Co, and the simulation results were verified through experiments. The results show that the method in this paper can accurately describe the low-energy tail of the γ-ray energy spectrum of the two CZT detectors, and the obtained simulated γ-ray energy spectrum is basically consistent with the full-spectrum characteristics of the measured energy spectrum.