基于蒙特卡罗模拟的α能谱拖尾分析

α能谱测量是通过对放射性核素释放α粒子能量的测量来实现核素识别和定量分析的技术.α能谱易受测量样品形态的影响,存在着向低能拖尾的现象,这降低了α能谱测量的准确性.为了分析α能谱谱形特点,采用蒙特卡罗程序Geant4模拟了~(241)Am源的α能谱,并对可能造成~(241)Amα能谱峰拖尾的因素进行了模拟分析.结果表明,~(241)Am源上沉积的灰尘是其α能谱峰拖尾的主要原因;采用最小二乘法拟合可以对沉积灰尘的粒径分布进行估计.这项工作也表明基于蒙特卡罗模拟的α能谱分析可获得测量样品更多特性(如形状),有助于提高α能谱的分析能力.

The Analysis of Alpha Spectrum Peak Tailing Based onMonte Carlo Simulation

Alpha spectrum measurement is an identification and quantitative analysis method of alpha radionuclide,which measures the alpha particle energy releasing from the radionuclide.Alpha spectrum in vacuum is very sensitive to the characteristics of alpha samples.The alpha spectrum peak always tails to the low energy,which lower the accuracy of the alpha spectrum analysis.For finding the reason of the tailing,the ²⁴¹Am alpha spectrum is simulated with different parameters using Monte Carlo program Geant4,and compared with the ²⁴¹Am measurement spectrum.The result shows the dust depositing on the ²⁴¹Am source is the main reason for the spectrum tailing,and the diameter distribution of the dust may be evaluated by the least square method.This work also shows that the Monte Carlo simulation will be helpful to improve the ability of the alpha spectrum analysis for finding the alpha sample property.