基于虚拟刻度原理对放射性体源效率刻度方法的发展  

Development of Efficiency Calibration Method for Radioactive Volume Sources Based on Virtual Calibration Principle

作　　者：许丰 郭建友[1] 於国兵 徐平 张建[4] XU Feng;GUO Jianyou;YU Guobing;XU Ping;Zhang Jian(School of Physics and Optoelectronics and Engineering,Anhui University,Hefei 230601,China;Radiation Environment Supervision Statio,Anhui Provincial Department of Ecology and Environment Protection,Heifei 230071,China;School of Nuclear Science and Technology,University of Science and Technology of China,Hefei 230027,China;School of Nuclear Technology and Automation Engineering,Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]安徽大学物理与光电工程学院,合肥230601 [2]安徽省生态环境保护厅辐射环境监督站,合肥230071 [3]中国科学技术大学核科学技术学院,合肥230027 [4]成都理工大学核技术与自动化工程学院,成都610059

出　　处：《原子核物理评论》2022年第3期352-358,共7页Nuclear Physics Review

基　　金：国家自然科学基金资助项目(11935001)

摘　　要：采用蒙特卡罗模拟计算的方法,标定能够适用于不同HPGe探测器上的体源虚拟点源位置,需要对点源、体源的探测效率进行模拟计算。通过^(241)Am、^(137)Cs、^(60)Co点源和体源研究了HPGe晶体尺寸、类型对它们的虚拟点源位置的影响,模拟结果表明^(241)Am虚拟点源位置随着探测器尺寸、类型的不同呈现明显的差异性,说明虚拟刻度原理对于探测器表面的小体积样品测量在低能区间是不可取的,最后采用^(137)Cs、^(60)Co源得出体源高度与虚拟点源位置的半经验公式。通过实验室两台HPGe探测系统对尺寸Φ70 mm×65 mm标准土壤体源的探测效率进行计算,与模拟探测效率值、虚拟点源效率表征结果对比分析,验证了拟合一组表征虚拟点源位置的半经验公式是可行的。实验结果表明,对γ能量区间在300~2000 keV进行体源的虚拟刻度时,选择可靠的定标源即可建立体源和虚拟点源位置的关系。这为解决监测工作中样品与探测器之间重复进行探测效率校准的问题提供了新的途径。Using the Monte Carlo simulation method,the virtual point source position of the volume source for different HPGe detectors can be quickly obtained.In the calculation,it is necessary to simulate the detection efficiency of the point source and the volume source.The effects of the size and type of HPGe crystals on their virtual point source positions were investigated through^(241)Am,^(137)Cs,^(60)Co point sources and volume sources.The simulation results show that the virtual point position of the^(241)Am source presents obvious differences.In the low energy range,the VPS calibration method is not valid in the measurement of small-volume samples of the surface of the detector.Finally,the semi-empirical formula for the height of the volume source and the position of the virtual point source is obtained by using the^(137)Cs and^(60)Co sources.In the test measurement,the detection efficiency of two types of HPGe detectors was calibrated using the standard soil source of the size of 70mm×65 mm.Compared with the simulated detection efficiency curve and the calculation results of virtual point source efficiency,the validity of the semi-empirical formula was verified.In the gamma energy range of 300~2000 keV,the relationship between the position of the volume source and the virtual point source can be established through a suitable radioactive source.This study provides a new approach in the radiation measurement to avoid the repeated detection efficiency calibration in detectors.

关 键 词：虚拟点源 效率刻度 LabSOCS 体源 

分 类 号：TL81[核科学技术—核技术及应用]