γ射线谱中符合相加修正系数的Monte-Carlo模拟

Monte-Carlo Simulation of the Coincidence-summing Corrections for γ-ray Spectrometry

用Monte Carlo方法模拟放射性核素的衰变过程,得到用HPGe探测器应能测到的多道γ能谱理论谱形,同时给出各特征能峰的探测效率和各特征峰的真符合相加修正系数。采用本方法开发的I、140Co、131Cool2000软件,可模拟60Co、88Y、134Cs、133Ba、95Nb、57Co、103Ru、106Ru、110Agm、124Sb、144Ce、65Zn、58La、241Am、99Mo、166Hom、152Eu、125Sb、214Bi、212Bi(α衰变链)和208T1,共计24种核素的衰变过程。对于60Co圆柱形体源发射的两条主要γ射线进行测量和分析结果表明:符合修正系数的模拟计算值与实验值在±1%的偏差范围内相符。同时给出了一种校正同轴探测器死层厚度和冷指尺寸的方法。

A computer code, Cool2000, was developed. It can be used to calculate the theoretical multi-channels γ-ray spectra and coincidence-summing corrections factors by simulating the processes of the natural decay series in γ-ray spectrometry with Monte-Carlo method, and to simulate the decay schemes of 24 nuclides, such as 60Co, 88Y, 134Cs, 133Ba, 134Ba, 95Nb, 57Co, 103Ru, 106Ru, 110Agm, 124Sb, 144Ce, 65Zn, 58Co, 131I, 140La, 241Am, 99Mo, 166Hom, 152Eu, 125Sb, 214Bi, 212Bi (α decay series) and 208T1. For a cylindrical 60Co source, the coincidence-summing corrections from theoretical calculation (Cool2000) and experimental results agree with each other within the deviation ±1%. An applied method obtained the thickness of dead layer and the size of cooling finger for co-axial HPGe detector is also given.