双拟合方法在快速放射性检测系统中的应用

本文构建了一种用于测量食品中低水平放射性的快速放射性检测系统,提出采用双拟合方法对测量的γ能谱特征峰进行分析。在预设的能窗内通过第1次曲线拟合得到特征峰的基本信息,然后在特征峰位的5σ区间内确定峰区边界。通过第2次曲线拟合自动得到特征峰的净面积,完成快速放射性检测系统的定量分析。利用双拟合方法对标样进行测量、计算、分析,得到检测系统对137Cs核素的判断限、探测限、定量下限与测量时长、测量相对标准误差之间的关系。当检测时间为20 min时,系统的探测限约为8 Bq/L。若相对标准误差为15%,定量下限约为16 Bq/L。结果表明,双拟合方法可应用于快速放射性检测系统的数据处理,可对低水平放射性核素进行定性与定量分析。

Application of Double-fitting Method in Rapid Radioactive Inspection System

A rapid radioactive inspection system was designed to measure the low-level radioactivity in the food.The double-fitting method was proposed to analyze the characteristic peak of measured spectrum.The curve fitting was taken to get the initial parameters, and then the boundary of characteristic peak could be determined by the interval range from ic-5σ to ic+5σ.The second curve fitting was taken to automatically obtain the net area of characteristic peak, and the quantitative analysis of rapid radioactive inspection system could be completed.At last, the double-fitting method was used to measure, compute and analyze the standard sample of 137Cs.Based on these data, critical limit, detection limit and determination limit were calculated with different collecting time intervals and measurement relative standard errors.When the inspection time interval is 20 min, the detection limit of system is 8 Bq/L.If the relative standard error is 15%, the determination limit is about 16 Bq/L.The double-fitting method can be applied to the data processing of rapid radioactive inspection system, and can be used for qualitative and quantitative analysis of the low-level radioactivity.