用内充气正比计数管准确测量^(131)Xe^m活度浓度  

Accurate measurement of ^(131)Xe^m activity concentration by internal gas proportional counting system

作　　者：李奇[1] 王世联[1] 樊元庆[1] 赵允刚[1] 张新军[1] 贾怀茂[1] 刘蜀疆[1] 常印忠[1] 

机构地区：[1]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：《核技术》2018年第1期45-49,共5页Nuclear Techniques

基　　金：国家自然科学基金青年科学基金(No.11505082)资助~~

摘　　要：^(131)Xe^m、^(133)Xe^m、^(133)Xe和^(135)Xe是全面禁止核试验条约(Comprehensive Nuclear-Test-Ban Treaty,CTBT)监测地下核试验最重要的核素。氙同位素活度通常采用HPGeγ能谱法和β-γ符合法等相对方法测量,准确刻度测量系统的探测效率是氙同位素活度准确测量的关键。本文介绍了用内充气正比计数管系统通过长度补偿法准确测量^(131)Xe^m活度浓度的方法,^(131)Xe^m活度浓度测量结果为(1.75±0.01)Bq·mL^(–1),为相对测量系统的探测效率刻度提供了活度标准。[Background] Due to the chemical inertness, the noble gases escape more easily from underground nuclear explosions into atmosphere than the fission products in solid form. Among the noble gases, four of radioxenon isotopes, i.e. 131Xem, 133xem, 133Xe and 135Xe, have high fission yields with half-lives of several hours to several days, which can be detected after long distances diffusion from where they were released. So these four radioxenon isotopes play a key role for underground nuclear test monitoring compliance with comprehensive nuclear-test-ban treaty （CTBT）. Accurate measurement of radioxenon isotopes activities is a key technique to identify characteristic of nuclear test from the monitoring data. [Purpose] Radioxenon isotopes activities are usually determined using relative measurement methods--HPGe y spectrometers or 13-y coincidence systems. The detection efficiency calibration of the relative measurement system by standard samples is the critical factor of these relative measurement methods. [Methods] This article describes the process and method of accurate measurement of activity concentration of 131Xem by internal gas proportional counting system which adopted length-compensated method. [Results] The activity concentration of 131xem is determined to be （1.75±0.01） Bq.mL-1 using internal gas proportional counters with corrections for dead time, background, discrimination, end effects and wall effects. [Conclusion] The activity concentration of 131xem sample was measured accurately, which can be used to calibrate detection efficiency of relative measurement system as a standard sample.

关 键 词：放射性氙同位素 活度浓度 内充气正比计数管 

分 类 号：TL816.4[核科学技术—核技术及应用]