一个PIXE-RBS离子束分析系统的刻度

摘要

四川大学原子核科学技术研究所依托2.5 MeV范德格拉夫静电加速器搭建了质子诱发X射线荧光分析(Proton Induced X-ray Emission,PIXE)与卢瑟福背散射分析(Rutherford Backscattering Spectrometry,RBS)相结合的离子束分析系统,描述了该分析系统和刻度过程.通过10个金属单质的PIXE-RBS测量,刻度得到的仪器常数H值是一条随能量变化的曲线,然后采用最小二乘法拟合确定了X射线探测器前的Mylar膜有效厚度、选择性滤膜的有效厚度和中心小孔大小,从而得到H值.为了对刻度H值进行检验,在相同实验条件下测量了标准粘土样品元素成分,测量数据与证书数据符合得较好.刻度结果将用于以后的PIXE-RBS分析.%Background: An ion beam analysis system combining proton induced X-ray emission (PIXE) and Rutherford backscattering spectrometry (RBS) has been established based on the 2.5-MeV Van de Graaff accelerator facility in Institute of Nuclear Science and Technology, Sichuan University. Purpose: Calibration of this PIXE-RBS system must be done before further quantitative analysis. The aim is to calibrate this PIXE-RBS system for future quantitative analysis. Methods: 10 single-element thick pure metal samples were measured by PIXE-RBS under experimental condition to determine the so-called instrumental constant H. The least square fit method was utilized to determine the effective thickness of Mylar and Al absorbers and aperture diameter of the funny filter in front of the X-ray detector. Results: The measured H values calculated from experimental spectra for K-shell X-rays of ten single-element thick pure metal samples were a function of X-ray energy, and the H values recalculated using aforementioned three effective values became a constant. A clay standard sample was measured at the same experimental condition to test the accuracy of the calibration, and the measured elemental content values and certified values are in good agreement. Conclusion: The accuracy of the calibration was satisfactory and the calibration results will be used for future PIXE-RBS analysis.