低本底γ能谱实验室铅室放射性本底变化分析探讨  

Analysis of background variations in low-background γ-ray spectrometer with lead shielding

作　　者：杨宝路 拓飞[1] 周强[1] 张京[1] 李文红[1] 李则书 Yang Baolu;Tuo Fei;Zhou Qiang;Zhang Jing;Li Wenhong;Li Zeshu(Key Laboratory of Radiological Protection and Nuclear Emergency,National Institute for Radiological Protection,Chinese Center for Disease Control and Prevention,Beijing 100088,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辐射防护与核应急中国疾病预防控制中心重点实验室,北京100088

出　　处：《中华放射医学与防护杂志》2018年第10期774-778,共5页Chinese Journal of Radiological Medicine and Protection

基　　金：国家自然科学基金（21806156）;科技部基础性工作专项资金（2014FY211000）

摘　　要：目的 探讨γ能谱仪本底中天然放射性核素净计数率的变化规律，为降低本底涨落对样品测量的影响提供科学依据。方法 收集两台高纯锗γ能谱仪在2013-2017年间不定期测量的本底谱，记录天然放射性核素210Pb、234Th、212Pb、214Pb、208Tl、214Bi、228Ac和40K特征峰的净计数率，运用统计学方法分析其净计数率的变化。结果 谱仪本底中210Pb、234Th、212Pb、214Pb、208Tl、214Bi、228Ac和40K的净计数率不同，其中214Pb、214Bi和40K的净计数率明显高于210Pb、234Th、212Pb、208Tl和228Ac。2013-2017年间，8种天然放射性核素的各自净计数率差异无统计学意义（P〉0.05），但是214Pb和214Bi的净计数率变异系数均在50%以上。结论 用γ能谱仪测量样品中天然放射性核素的活度浓度，当活度浓度较低时，须用近期测量的本底进行扣除，以保证结果的准确性。Objective To study the variation in net count rates of natural radionuclides in background of gamma-ray spectrometer, so as to provide a scientific basis for reducing the effect of background fluctuations on sample measurement. Methods The unscheduled background spectrum obtained using two high-purity gamma-ray spectrometers during 2013-2017 were collected, and then the net count rates of 210Pb, 234Th, 212Pb, 214Pb, 208Tl, 214Bi, 228Ac and 40K were calculated and analyzed by aid of statistical method. Results There was a significant difference in the net count rates of 210Pb, 234Th, 212Pb, 214Pb, 208Tl, 214Bi, 228Ac and 40K in the background spectrum of gamma-ray spectrometer, and the net count rates of 214Pb, 214Bi and 40K was significantly higher than those of 210Pb, 234Th, 212Pb, 208Tl and 228Ac. There were no significant differences in the net count rates of these eight natural radionuclides from 2013 to 2017, respectively （P〉0.05）. However, the coefficients of variation in the net count rates for 214Pb and 214Bi were both greater than 50%. Conclusions When the activity concentration of natural radionuclides is determined in a sample by gamma-ray spectrometer, it is critical to subtract the background spectrum obtained recently to ensure the accuracy of the measurement, especially for the low activity concentration of natural radionuclide to be measured.

关 键 词：低本底γ能谱仪 铅室 天然放射性核素 

分 类 号：R14[医药卫生—公共卫生与预防医学]