基于Geant4模拟^(37)Ar活度测量计数损失的修正方法  

Counting loss correction in ^(37)Ar activity measurement based on Geant4 simulation

作　　者：孔淑颖 杨宝路 王仁生 张明[3] 路天翔 拓飞[1] KONG Shuying;YANG Baolu;WANG Rensheng;ZHANG Ming;LU Tianxiang;TUO Fei(National Institute for Radiological Protection,Chinese Center for Disease Control and Prevention,Beijing 100088 China;School of Radiation Medicine and Protection,Medical College of Soochow University,Suzhou 215123 China;National Institute of Metrology,Beijing 100029 China)

机构地区：[1]中国疾病预防控制中心辐射防护与核安全医学所,北京100088 [2]苏州大学医学部放射医学与防护学院,江苏苏州215123 [3]中国计量科学研究院,北京100029

出　　处：《中国辐射卫生》2023年第2期93-97,101,共6页Chinese Journal of Radiological Health

摘　　要：目的 采用内充气正比计数器开展放射性惰性气体^(37)Ar活度绝对测量时,需要对计数器阈值以下的计数损失进行修正。方法 利用Geant4蒙特卡罗模拟软件,构建正比计数器模型并获得^(37)Ar能量沉积谱,模拟分析计数损失产生原因及修正方法。结果 模拟计数器工作压强60 kPa下对光子探测效率,结果仅为38.7%,漏计数损失主要来源于光子逃逸产生的壁效应,可通过增大工作气体压强的方式减小,并通过外推的方式予以修正。模拟压强100 kPa下,壁效应影响为4.4%,与实验偏差在0.6%以内。结论 可利用Geant4确定计数器阈值以下漏计数修正因子,从而实现正比计数器法对^(37)Ar活度的准确测量。Objective To correct the counting loss of ^(37)Ar below the activity threshold during the measurement of the absolute activity of the inert radioactive gas ^(37)Ar using the proportional counter filled with gas.Methods Monte Carlo simulation with Geant4 was performed to establish a proportional counter model and output the energy deposition spectrum of ^(37)Ar,which were used to simulate and analyze the causes and correction of counting loss.Results The photon detection efficiency was only 38.7%at 60 kPa.The counting loss was mainly caused by the wall effect produced by the photons,which could be reduced by increasing the gas pressure and corrected by extrapolation.The influence of wall effect at 100 kPa was 4.4%,and the deviation between simulation and experiment was<0.6%.Conclusion A factor could be calculated by Geant4 simulation for the correction of counting loss,thus achieving the accurate measurement of ^(37)Ar activity by proportional counter.

关 键 词：^(37)Ar GEANT4 正比计数器 探测效率 计数损失修正 

分 类 号：TL811[核科学技术—核技术及应用]