基于像素型CZT探测器的深度灵敏与能量校正技术研究  

Research on depth sensitivity and energy correction technology based on pixel CZT detector

作　　者：吴俊[1,2] 姜小盼 章志明[2] 汪超[2] 向宇 李岩 曾国强 WU Jun;JING Xiaopan;ZHANG Zhiming;WANG Chao;XIANG Yu;LI Yan;ZENG Guoqiang(The College of Nuclear Technology and Automation Engineering,Chengdu University of Technology,Chengdu 610059,China;Beijing Engineering Research Center of Radiographic Techniques and Equipment,Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]成都理工大学核技术与自动化工程学院,成都610059 [2]中国科学院高能物理研究所,北京市射线成像技术与装备工程技术研究中心,北京100049

出　　处：《物探化探计算技术》2020年第3期401-406,共6页Computing Techniques For Geophysical and Geochemical Exploration

基　　金：国家自然科学基金(11805215,11675191);国家重点研发计划项目(2017YFC0602101)。

摘　　要：碲锌镉(TeZnCd)探测器是近年来兴起的一种新型半导体探测器,其具有能量分辨率高、空间分辨率高、便携性好、且能在室温下正常工作等优点,在现代放射性物探的γ能谱测量中具有很好的应用潜力。但由于碲锌镉材料自身的空穴捕获效应,对高能伽玛射线的电荷收集不完全,制约了其在铀矿放射性勘探的应用。这里通过有限元仿真,研究CZT晶体内部的权重势分布,搭建实验平台,利用准直源射入CZT晶体内不同深度,并通过自主设计的电路读出探测器阴、阳极信号,采用C/A比值法获取探测器晶体内作用深度与电荷收集效率的关系,并基于该研究结果对137Cs能谱进行校正,校正后FWHM@662keV从4.20%提升到2.65%,极大地提升了能量分辨能力,且“低能拖尾”现象也得到了明显地改善,验证了深度灵敏技术及其应用于能谱校正的可行性,从而提高了碲锌镉探测器对高能伽玛射线的能量分辨率,使其可能应用于新型放射性物探仪器,提高对铀矿等放射性物质勘查的精度。CdZnTe detector which has high energy resolution,high spatial resolution and good portability,is a new type of semiconductor detector.CZT detectors can work at room temperature,which causes significant potential on energy spectrum measurement of radioactive geophysical prospecting.However,the charge collection of high energy gamma rays are incomplete due to the hole trapping effect.This restricts the application on Uranium radioactivity prospecting.In our work,we used finite element simulation tools to calculate the weight potential distribution in CZT detectors,and then used collimated rays to incident into CZT crystal at different depths.Both signals from cathode and anode were read out by the self-designed circuit,which were used to research the relationship between the charge collecting efficiency and the incident depths.By means of the relationship,the FWHM@662keV of 137Cs was modified from 4.2%to 2.65%which verified the feasibility of depth sensitivity technique and its application in energy spectrum correction.The improvements of the energy resolution helps CZT detectors to be used in new radio-geophysical instrument.This can improve the precision of radio-prospecting for uranium ore.

关 键 词：TeZnCd 伽玛能谱 权重势 C/A比值法 电荷收集效率 

分 类 号：P631[天文地球—地质矿产勘探]