利用Geant4模拟计算角关联对HPGe探测器符合相加效应的影响  

Simulation of the Angular Correlation Impact on HPGe Detector Coincidence Summing Effect by Geant4

作　　者：徐晨曦 倪建忠[1] 余功硕[1] 刘杰[1] XU Chen-xi;NI Jian-zhong;YU Gong-shuo;LIU Jie(Northwest Institute of Nuclear Technology,Xi'an 710024,China)

机构地区：[1]西北核技术研究所,西安710024

出　　处：《现代应用物理》2019年第1期3-9,共7页Modern Applied Physics

摘　　要：根据近似抽样原理建立了γ-γ角关联的蒙特卡罗抽样方法,并对该方法的正确性进行了验证。利用Geant4软件分别计算了^(60)Co,^(133)Ba和^(134)Cs能谱中4条不同γ射线的符合相加因子。结果表明:针对不考虑角关联和考虑角关联2种情况,计算得到的符合相加因子之间的相对偏差均小于2.0%。同时,还模拟计算了能量为1 875.0keV的γ射线以0(5)5(5)0跃迁方式与能量为140.0keV的γ射线级联下的符合相加因子,考虑角关联与不考虑角关联情况下,计算得到的符合相加因子之间的相对偏差可达7.75%。因此,角关联对HPGe探测器符合相加效应的影响并不相同,而是与γ射线的能量、跃迁方式以及放射源与探测器间的相对位置等因素有关。在模拟计算符合相加因子时,需考虑角关联效应。According to the principle of approximate sampling,a Monte Carlo sampling method with 60Coγ-γangular correlation is established,and the validity of the method is verified.The coincidence summing coefficients of fourγrays from 60Co,133Ba and 134Cs spectra are calculated by Geant4 code.The results indicate that the relative deviation between the calculated coincidence summing coefficients is less than 2.0%with or without consideringγ-γangular correlation.At the same time,the coincidence summing coefficients ofγrays with energy of 1 875.0 keV cascaded withγrays with energy of 140.0 keV in 0(5)5(5)0 transition mode are also calculated.The relative deviation between the calculated coincidence summing coefficients can reach 7.75%when considering the angular correlation and not considering the angular correlation.Therefore,the impact of angular correlation on the coincidence summing effect of HPGe detectors is not same,but is related to the energy ofγrays,the mode of energy transition and the relative position of radiation source and the detectors.Angular correlation effect should be considered when calculating the coincidence summing coefficients in simulation.

关 键 词：HPGE 符合相加因子 角关联 GEANT4 

分 类 号：TL816.2[核科学技术—核技术及应用]