基于概率密度的面源刻度法对碘盒中^(131)I的定量监测

Quantitative monitoring of ^(131)I in iodine cartridge using probability density calibration method of disk source

本文引入概率密度函数,对^(131)I特征γ射线的面源效率与高度进行函数关系拟合,采用积分法对非均匀分布碘盒体源进行效率刻度,然后根据正反放置下的效率比值K与分布参数α联立构建数学模型,确定了碘盒中^(131)I的活度。为了验证该方法在实验中的可行性,通过对气态碘采集实验获得的非均匀碘盒样品进行分析,采用概率密度面源刻度方法得到的碘盒总活度与碘盒拆解-搅拌-回填处理得到的总活度比较,以^(131)I特征γ射线364.48 keV为分析射线,两者的均匀偏差为5.71%,最大偏差为8.54%。结果表明:通过概率密度函数的面源刻度方法,可以快速、方便地获得不均匀分布碘盒的探测效率,为实现气态碘的定量监测提供一条可行的途径。

In this study,we used the integral method of the probability density function to evaluate the detection efficiency of an inhomogeneous iodine cartridge source by fitting the function relationship between the efficiency of the ^(131)I γ-ray and the height of the disk source from the detector.We constructed a mathematical model by combining the efficiency ratio of the positive and negative placement,K,and the distribution parameter,α,to determine the activity of ^(131)I in the iodine cartridge.To verify this method,we analyzed the inhomogeneous iodine cartridge samples obtained from a gaseous iodine collection experiment.The average deviation of the total activity of ^(131)I,calculated by using ^(131)I γ-ray(364.48 keV),in the iodine cartridge between our method and the homogeneous iodine cartridge source obtained by employing disassembly-stirring-backfilling was 5.71%,and the maximum deviation was 8.54%.The results showed that the disk source calibration method of the probability density function can be used to determine the detection efficiency of inhomogeneous iodine cartridges,thereby providing a feasible method for monitoring gaseous iodine.