低本底实验室γ谱仪探测限研究  

Study on Minimum Detectable Concentration of the γ Spectrometer In Low-background Laboratory

作　　者：王茜[1] 李雪泓 李春阳[1] 曾奕[1] 杜云武[1] 王艳[1] 余强 WANG Qian;LI Xue-hong;LI Chun-yang;ZENG Yi;DU Yun-wu;WANG Yan;YU Qiang(Sichuan Management & Monitoring Center Station of Radioactive Environment, Chengdu 611139, China)

机构地区：[1]四川省辐射环境管理监测中心站,成都611139

出　　处：《四川环境》2018年第6期118-123,共6页Sichuan Environment

摘　　要：使用一台高纯锗γ谱仪在一般实验室和低本底实验室铁室中对高纯锗γ谱仪铅室本底计数率水平和3种不同介质样品γ核素进行测量分析,研究低本底实验室铁室中高纯锗γ谱仪铅室本底计数率水平的优化程度,分析测量气溶胶、生物灰、河水样品中 ^(137)Cs、^(134)Cs两种核素的探测限值,研究探测限值与测量时间的变化趋势,以及对于测量时间的优化程度。结果表明,低本底实验室铁室测量高纯锗铅室本底计数率水平比一般实验室降低了25. 6%。按不同时间测量的探测限值拟合曲线表明 ^(137)Cs、^(134)Cs两种核素的探测限值均随时间的增加而下降。不同介质样品测量中,核素 ^(137)Cs探测限值优化百分比范围为28. 81%～29. 63%,核素^(134)Cs探测限值优化百分比范围为21. 44%～25. 12%。核素 ^(137)Cs的探测限优化百分比均大于核素^(134)Cs,核素 ^(137)Cs的探测限优化程度比^(134)Cs的探测限优化程度大。在应急情况下,可结合低本底实验室铁室的测量分析结果,选择与可探测到的最低活度相对应的最优测量活时间,提高应急监测能力。A high-purity Ge gamma spectrometer was used to measure the background level of its lead chambers and the gamma nuclides of three different media samples in general laboratory and low-background laboratory iron chambers,to study the optimization of the background level of the high-purity Ge lead chamber in low-background laboratory iron chambers.To measure the minimum detectable concentration(MDC)of 137Cs and 134Cs in the samples of the aerosol,bio-ash and river water,and study the change trend of the MDC and the measurement time,and the degree of optimization of the measurement time.The results showed that the background level of the high-purity Ge lead chamber in the low-background laboratory iron chamber reduced 25.6%compared with the general laboratory.The fitting curve of the MDC at different times indicated that the MDC of the two nuclides of 137Cs and 134Cs decrease with time.In the measurement of different medium samples,the optimum percentages of the MDC of nuclide 137Cs ranged from 28.81%to 29.63%,and the optimum percentages of the MDC of nuclide 134Cs ranged from 21.44%to 25.12%.The MDC and the optimization percentage of the radionuclide 137Cs were both greater than that of the radionuclide 134Cs.In the case of emergency,we can combine with the measurement and analysis results of the low-background laboratory iron chamber,to select the optimal measurement live time corresponding to the detectable minimum activity and to improve the emergency monitoring capability.

关 键 词：低本底实验室 Γ谱仪 探测限 

分 类 号：X837[环境科学与工程—环境工程]