α、β放射性测量中计数效率与取样量的关系

Relationship between counting efficiency and sample volume in α,β radioactive measurement

目的分析α、β放射性测量中计数效率与取样量的关系，以便在α、β放射性测量中使用准确的计数效率进行计算。方法以50—250mg标准物质粉末，制备成标准源系列，分别进行计数效率测定，用SPSS软件的曲线估计功能分析计数效率和取样量之间可能的曲线关系，选择拟合程度高且便于使用的拟合曲线模型作为计数效率与取样量之间的曲线关系。同时研究不同通道之间的差异。结果同一通道d计数效率与取样量对数曲线、二次曲线和三次曲线相关性较高，r方值大于等于0．995，对于不同通道，其拟合曲线方程不同；同一通道β计数效率不受取样量的影响，50-250mg标准物质粉末，在同一通道β计数效率的相对标准偏差为2．9％～5．9％；对于不同通道，其β计数效率均值不同。结论进行α放射性测量时，对于同一通道，可以以取样量对α计数效率作对数曲线、二次曲线或三次曲线，由曲线方程求得50～250mg取样量对应的α计数效率作为该样品的仪计数效率，其中建立对数曲线较为简便，建议首选对数曲线，对于不同通道，其拟合曲线方程不同，应分别进行拟合；进行β放射性测量时，可采用同一通道β计数效率均值作为该样品的β计数效率；对于不同通道，其β计数效率均值不同，应分别进行计数效率校正。

[ Objective]To analyze the relationship between counting efficiency and sample volume in α、β radioactive measurement, in order to use accurate counting efficiency to calculate in α、β radioactive measurement. [ Methods ] 50-250 mg standard material powder was used to make up the standard source series, the counting efficiency was detected, the possible curvilinear relationship between counting efficiency and sample volume was analyzed by curve estimation function of SPSS software, fitting curve model with high fitting degree and easy to use was selected as curvilinear relationship between counting efficiency and sample volume. The difference of different channels was studied. [ Results ] The correlation of α counting efficiency of the same channel and logistic curve, binary curve and cubic curve of sample volume was higher, r t〉0. 995. For different channel, the fitting curve equations were different. For the same channel, β counting efficiency was not affected by the sample volume. The RSD of β counting efficiency in the same channel of 50-250 mg standard material powder was 2.9%-5.9%. For the different channels, the average of β counting efficiency was different. [ Conclusion ] Making α radioactive measurement, for the same channel, we can use sample volume to ot counting efficiency for logistic curve, binary curve or cubic curve, calculate the α counting efficiency of 50-250 mg sample volume as the α counting efficiency of this sample. Building logistic curve is sample, we suggest first choose it. For differ- ent channel, the fitting curve equations were different, it should be fitted respectively. Making β radioactive measurement, the average of β counting efficiency of the same channel can be as the β counting efficiency of this sample. For different channel, the av- erage of β counting efficiency was different, we should make counting efficiency correction respectively.