环境样品装样量对低能γ射线放射性核素活度测量的影响  

The Influence of Environmental Sample Quantities to the Activity Measurement of Low-energy γ Radionuclide

作　　者：王芳娜[1] 徐家云[1] 张洁[1] 

机构地区：[1]四川大学物理科学与技术学院,四川成都610064

出　　处：《核电子学与探测技术》2013年第5期548-552,共5页Nuclear Electronics & Detection Technology

摘　　要：为提高用HPGeγ谱仪测量环境样品中发射低能γ射线核素活度的准确性,研究了装样量对测量结果的影响。首先用蒙特卡罗方法模拟计算了不同能量γ射线探测效率与装样量(装样高度)之间的关系,由此得到了不同能量γ射线的全能峰计数与装样高度的关系,由此关系可以确定不同能量γ射线的最佳装样量。然后以土壤样品中的238U为例,分别模拟计算其92.6 keV标识γ射线在不同装样高度时的单能能谱和存在高能γ射线康普顿散射时的叠加能谱。结果表明:合适的装样高度可以在不明显减少全能峰净计数的情况下,有效降低由高能γ射线康普顿散射引起的本底误差。In the experiment of using HPGe γ spectrum instrument to measure the activity of low - energy T radi- onuclide in environmental sample,in order to improve the accuracy of the result, this paper studied the influ- ence of sample quantities on the accuracy of the result. Monte - Carlo method was firstly used to obtain the sim- ulative results of the relationship between the detection efficiency of different energy T - rays and different sam- ple quantity （ i. e. sample height） and thus the relationship between counts of the full - energy peak of different energy γ -rays and different sample height was obtained, then the optimal quantities corresponding to different energy γ- rays were determined. Secondly, taking 238 U of soil sample for example , energy spectrums of a single energy and energy spectrum mixed with Compton scattering from high - energy γ - rays of different sample quan- tities were simulated. It turned out that appropriate sample quantity can effectively reduce the background error caused by Compton scattering. Meanwhile, the net counts of full- energy peak isnt significantly reduced.

关 键 词：环境样品 装样高度 活度测量 蒙特卡罗方法 

分 类 号：X830.1[环境科学与工程—环境工程]