平面型CdZnTe探测器的能谱特性模拟  

Simulation of energy spectrum characteristics of planar CdZnTe detector

作　　者：朱伟峰 吴金杰[2] 汤显强 赵瑞[2] 鲁平周 屈冰冰 李梦宇 秦峰 ZHU Weifeng;WU Jinjie;TANG Xianqiang;ZHAO Rui;LU Pingzhou;QU Bingbing;LI Mengyu;QIN Feng(Chengdu University of Technology,Chengdu 610059,China;National Institute of Metrology,Beijing 100029,China;China Jiliang University,Hangzhou 310018,China)

机构地区：[1]成都理工大学,成都610059 [2]中国计量科学研究院,北京100029 [3]中国计量大学,杭州310018

出　　处：《核技术》2023年第5期60-66,共7页Nuclear Techniques

基　　金：国家市场监督管理总局技术保障专项(No.2022YJ33)资助。

摘　　要：CdZnTe(CZT)探测器是一种高原子序数的化合物半导体探测器,具有体积小、探测效率高、可在常温环境使用等特点,广泛应用于X、γ射线探测领域。为了更好地研究CZT探测器能谱特性的影响因素,通过Geant4软件建立探测器几何模型,模拟计算CZT晶体的本征探测效率和吸收率;根据Hecht公式计算电荷收集效率,通过收集晶体中的沉积能量和位置信息得到γ射线能谱;通过分析晶体的物理特性,探索其对探测器性能的影响。模拟计算结果表明:电荷收集不完整是影响探测器能谱性能的重要因素,当能量低于50 keV时,γ射线谱基本不受空穴尾迹的影响,而能量在50~100 keV的γ射线能谱受空穴尾迹的影响较为明显,高于100 keV的γ射线能谱受空穴尾迹的影响逐渐加重。通过增加偏压的方式可以降低空穴尾迹对能谱的影响,同时偏压的增加会使峰位产生偏移,偏移程度受最大电荷收集效率的影响。[Background]A CdZnTe(CZT)detector is a compound semiconductor detector with a high atomic number and high detection efficiency,it can be used at room temperatures to detect short wavelength radiation such as X-ray andγray.[Purpose]This study aims to investigate the factors affecting the energy spectrum characteristics of the CZT detector.[Methods]The geometric model of the detector was established by using Geant4 software,and the intrinsic detection efficiency and absorption rate of CZT crystal in the planar size of 10 cm×10 cm were simulated.The charge collection efficiency of the crystal was calculated using the Hecht formula and theγ-ray energy spectrum was obtained by collecting the deposition energy and position information in the crystal.By analyzing the physical properties of crystals,the impact of physical properties on detector performance was explored.[Results]Simulation results show that incomplete charge collection significantly influences the spectral performance of the detector.When theγray energy is less than 50 keV,the spectrum is not affected by hole wake whilst the influence of hole wake is more obvious when the energy is between 50 keV and 100 keV.The energy spectrum is gradually aggravated by the influence of hole wake when theγray energy is above 100 keV.[Conclusions]This effect of hole wake for CZT detector can be reduced by increasing the bias voltage,but the increased bias voltage shifts the spectrum's peak,and the shift amount is determined by the maximum charge collection efficiency of the crystal.

关 键 词：CZT探测器 本征探测效率 吸收率 电荷收集效率 空穴尾迹 

分 类 号：TL814[核科学技术—核技术及应用]