提高HPGe γ能谱法测量^(131)Xe^m和^(133)Xe^m探测灵敏度的方法研究  

Method to Enhance Detection Sensitivities of ^(131)Xe^m and ^(133)Xe^m Measured by HPGeγSpectrometer

作　　者：李奇[1,2] 王世联[2] 赵允刚[2] 樊元庆[2] 贾怀茂[2] 张新军[2] 陈占营[2] 刘蜀疆[2] 常印忠[2] 于伟翔[1] 

机构地区：[1]中国原子能科学研究院核数据重点实验室,北京102413 [2]禁核试北京国家数据中心和北京放射性核素实验室,北京100085

出　　处：《原子能科学技术》2016年第12期2240-2244,共5页Atomic Energy Science and Technology

基　　金：国家自然科学基金青年基金项目资助(11505082)

摘　　要：放射性氙同位素(^(131)Xe^m、^(133)Xe^m、^(133)Xe和^(135)Xe)具有化学惰性、裂变产额大、易释放的特点,是监测核试验尤其是地下核试验最关键的核素之一。^(131)Xe^m和^(133)Xe^m的γ射线发射概率小,X射线能量完全相同,致使HPGeγ能谱法测量^(131)Xe^m和^(133)Xe^m活度的探测灵敏度低。针对这一技术难题,本文研究建立了^(131)Xe^m和^(133)Xe^m活度测量的X/γ射线交互分析方法。利用贝叶斯方法推导了γ能谱中净峰面积概率分布,根据得到的^(131)Xe^m和^(133)Xe^m X射线和γ射线净峰面积分布构建了活度分布的似然函数,采用最大似然法得到了^(131)Xe^m和^(133)Xe^m活度。相对于仅用γ射线分析,提高了^(131)Xe^m和^(133)Xe^m的探测灵敏度。Owing to their inert chemical properties ,large fission yields ,and abilities to easily vent into the atmosphere ,detection of radioactive xenon isotopes （131 Xem ,133 Xem , 133 Xe and 135 Xe） is one of the most effective technology of underground test monitoring . Due to the lower γ ray emission probability and energy overlapping of X ray , the detection sensitivities of 131 Xem and 133 Xem are lower measured by using HPGe γspectrometer .To enhance the detection sensitivities of 131 Xem and 133 Xem ,an X andγray interactive analysis method was developed .The distribution of the net peak counts in γspectrum was deduced through Bayesian approach .The likelihood function of 131Xem and 133 Xem activities was established by using the distribution of net peak counts of X and γray .The activities of 131Xem and 133Xem were estimated by maximum likelihood method . The detection sensitivities of 131Xem and 133Xem are enhanced comparing with analyzing their γ ray .

关 键 词：探测灵敏度 放射性氙同位素 贝叶斯方法 最大似然法 

分 类 号：TL816.4[核科学技术—核技术及应用]