溴化铈闪烁探测器双能定向γ辐射取样技术研究  

Dual-energy targeted gamma radiation sampling technique based on cerium bromide scintillation detector

作　　者：刘洪武 葛良全[1] 吴霁桐 杨小峰[1] 邓志鹏 唐传丰 熊茂淋 LIU Hongwu;GE Liangquan;WU Jitong;YANG Xiaofeng;DENG Zhipeng;TANG Chuanfeng;XIONG Maolin(Applied Nuclear Technology in Geosciences Key Laboratory of Sichuan Province(Chengdu University of Technology),Chengdu 610059,China)

机构地区：[1]地学核技术四川省重点实验室(成都理工大学),成都610059

出　　处：《核技术》2023年第12期47-54,共8页Nuclear Techniques

基　　金：国家重点研发计划项目(No.2017YFC0602105);四川省科技计划项目(No.2020YJ0334)资助。

摘　　要：定向获取放射性待测体中放射性元素含量或放射性活度是地质勘查和放射性污染调查的一项重要工作。在定向γ辐射取样过程中,非待测体区域γ射线对测量结果形成极大干扰。本文基于同一放射性衰变系列中高、低能量γ射线在溴化铈闪烁探测器铅屏蔽层中线性衰减系数的差异,设计了一种溴化铈闪烁探测器双能定向γ辐射取样探头。当以214Bi放出的0.609 MeV、1.764 MeV γ射线为探测对象时,使用蒙特卡罗(Monte Carlo,MC)数值模拟得出双能定向γ辐射取样探头的最佳铅屏蔽层厚度为6 mm,定向比例系数为a=0.268、A=0.451。经4种干扰辐射体蒙特卡罗数值模拟和两个镭源物理实验验证表明,采用该定向比例系数得到的双能γ辐射探头铅屏蔽张角以内0.609 MeV的γ射线计数值与MC模拟值的平均相对误差为0.63%;经两个镭源物理实验验证表明,张角以内的0.609 MeVγ射线计数值与实测值的相对误差为±2.52%以内。在放射性混合标准模型和三个放射性模型上进行双能定向γ辐射取样结果表明,设计的新型双能定向γ辐射取样探头具有定向γ辐射取样功能,实测模型中铀含量与模型推荐值的相对误差均小于5%。[Background]The targeted acquisition of the radioactive element content or radioactivity in a radioactivity is an important task in geological exploration and radioactive pollution investigation.During the process of targeted gamma radiation sampling,gamma rays from non-target areas significantly interfere with the measurement results.[Purpose]This study aims to design a dual-energy targeted gamma radiation sampling probe that uses a cerium bromide scintillation detector on the basis of the difference in the linear attenuation coefficients of the high-and low-energy gamma rays from the same radioactive decay series in the lead shielding layer of the detector.[Methods]Firstly,Monte Carlo(MC)numerical simulations were employed to determine the optimal lead shielding layer thickness for the dual-energy targeted gamma radiation sampling probe detecting targets of the 0.609 MeV and 1.764 MeV gamma rays emitted by 214Bi.Then,the directional proportionality coefficients were calculated and applied to obtaining 0.609 MeV gamma ray counts of dual energyγradiation probe within lead shielded angle.Finally,MC numerical simulations with four types of interfering radiation sources and physical experiments with two radium sources were conducted to validate the results that calculated using the directional proportionality coefficients.[Results]The simulation result of optimal lead shielding layer thickness for the dualenergy targeted gamma radiation sampling probe is 6 mm,and the calculated directional proportionality coefficients of a and A are 0.268 and 0.451,respectively.Validation results show that the relative error between the counts for the 0.609 MeV gamma rays within the shielded angle and the net peak area counts measured with the dual-energy targeted gamma radiation sampling probe for two radium sources is within ±2.52% with average relative error of 0.63%.The relative errors between the measured uranium content and recommended values in the tested models are all less than 5%.[Conclusions]The dual-energy targeted gam

关 键 词：双能定向γ辐射取样技术 铀矿勘查 定向比例系数 

分 类 号：TL99[核科学技术—核技术及应用]