用标准样品刻度γ能谱仪效率值的变化比较

Comparison of the Vary of the Efficiency for γ Spectrometry Calibrated by Using the Standard Sample

目的比较γ能谱仪刻度用标准样品探测效率的差别,为样品测量分析中的效率校正提供参考。方法利用水、鱼肉灰、蔬菜灰和大米灰四个标准样品,在同一台HPGeγ能谱仪进行测量分析,比较效率值的相对偏差。结果水样品与生物灰样品由于样品的几何形状和样品介质不同,导致各个能量点的效率值都有较大差别。三个生物灰样品仅装样密度不同,各个能量点的效率值略有差别。结论γ能谱仪刻度时应首先保障被测样品与效率刻度用样品在几何形状和介质上一致,其次是样品装样密度应尽量一致,当密度不一致时效率的偏差在低能部分表现较大,应注意样品中低能区的自吸收校正问题。

Objective To compare the difference of detection efficiency of the gamma ray spectrometer between different standard sample,and to provide reference for the efficiency correction in the sample measurement and analysis.Methods Water,fish meat,vegetables and rice ash four standard samples were used in the same HPGe gamma spectrometer for measurement and analysis,the relative deviation of efficiency value were obtained.Results Water samples and biological samples were different from the sample＇s geometry and the media,resulting in the difference of the efficiency value in each point.These three kinds of biological samples have different density,and the efficiency of each point is slightly different.Conclusion During the calibration,the efficiency of the sample should be consistent with the medium is consistent with.Secondly,the sample should be consistent with the density.The deviation of the efficiency of the density is larger in the low energy.