CsI光阴极在10-100 keV X射线能区的响应灵敏度计算  

Calculation of CsI photocathode spectral response in 10-100 keV X-ray energy region

作　　者：黎宇坤[1] 陈韬[1] 李晋[1] 杨志文[1] 胡昕[1] 邓克立 曹柱荣[1] Li Yu-Kun;Chen Tao;Li Jin;Yang Zhi-Wen;Hu Xin;Deng Ke-Li;Cao Zhu-Rong(Laser Fusion Research Center, China Academy of Sciences, Mianyang 621900, China)

机构地区：[1]中国工程物理研究院激光聚变研究中心,绵阳621900

出　　处：《物理学报》2018年第8期169-175,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11675157);中国工程物理研究院科学技术发展基金(批准号:2015B0102015;2015B0102016)资助的课题~~

摘　　要：为了满足10-100 keV高能X射线光电探测器研究的需要,对CsI光阴极在该能量范围的响应灵敏度进行了研究.基于高能量X射线光子与材料相互作用的物理过程,分析了康普顿散射等效应对CsI响应灵敏度的影响.推导了CsI的响应灵敏度与二次电子平均逃逸深度和光阴极厚度的关系式和二次电子平均逃逸深度与入射光子能量的关系式,计算了CsI在10-100 keV范围内的响应灵敏度,计算结果与实验测试数据相符,验证了分析与推导的可靠性.根据计算可以获得不同入射X射线能量下CsI光阴极的最佳厚度,从而为高能X射线光电探测器的设计优化提供了理论参考.CsI photocathode is widely applied to high energy X-ray detection. And the spectral response is an important character of CsI photocathode. In this paper, the interaction process of high energy X-ray with CsI is analyzed and the spectral response of CsI photocathode is calculated in a 10-100 keV range. The influences of Compton scattering,X-ray fluorescence radiation and Auger emission on the spectral response are analyzed in accordance with the physical process of high energy X-ray interaction with CsI photocathode. These influences prove to be negligible in comparison with photo-ionization influence. Thus only the photoelectric transition is taken into account in calculation. According to the analyses of the processes of the photoelectron creation, transition and escaping, the formula for CsI spectral response is deduced as a function of secondary electron mean escape depth and photocathode thickness. The formula of secondary electron mean escape depth is then deduced as a function of X-ray energy. These formulae indicate that the mean escape depth of the secondary electrons increases markedly with the rise of X-ray energy and has a remarkable influence on the CsI spectral response. The spectral responses for different CsI thickness values are then calculated in a range of 10-100 keV. The results show that 1000 nm CsI has the best response under 20 keV, while 10000 nm CsI has a higher response over 60 keV. Then the calculation data are compared with experimental data of Hara＇s and Khan＇s hard X-ray streak camera measurements. These data agree well with each other and prove that our calculation of CsI spectral response for high energy X-ray is reliable. The spectral responses to CsI thickness for 17.5 keV and 60 keV are also calculated and shown in figures. These calculation data match experimental data of Frumkin and Monte-Carlo simulation data of Gibrekhterman. The measurement error of Frumkin＇s experiment and the uncertainty of the secondary electron mean escape depth are considered to be the reasons fo

关 键 词：CsI光阴极 X射线 响应灵敏度 二次电子 

分 类 号：O434.1[机械工程—光学工程]