点源效率函数确定大体积样品的HPGe探测器γ射线峰效率

Point Source Function to Determine HPGe Detector γ-ray Peak Efficiency for Large Volume Samples

利用HPGeγ谱仪,用241Am、137Cs、60Co混合点源分别测量样品在5个高度上、不同剖面、不同位置的全能峰效率,通过最小二乘拟合确定了点源峰效率函数的拟合参数,用该点源效率函数对φ75mm×25mm的土壤样品的半径和高度数值积分计算可得到59.54、661.66、1173.2、1332.5keVγ射线全能峰效率。将点源效率函数数值积分计算的体源全能峰效率与实测标准体源全能峰效率以及LabSOCS无源效率刻度结果进行比较,相对偏差在10%内符合,说明该点源效率函数参数确定方法是正确的。同时,该点源效率函数在计算任意几何形状的样品得到了应用,积分计算了球状样品的探测效率,并与LabSOCS无源效率刻度结果进行比较,两者相对偏差在10%内符合。

Based on HPGe spectrometers, the full energy peak efficiencies at different height sample radius were obtained by the 241Am, 137Cs, 60Co mixed point sources, and the function parameters about the full energy peak efficiencies of point sources based on radius and height were fixed. The 59.54, 661.66, 1 173.2, 1 332.5 keV γ-ray’s detection efficiencies of 75 mm×25 mm sample were obtained,based on integrality radius and height of point sources. The detection efficiencies integrality by point sources function were consistent with the results of standard source and LabSOCS in 10%. Therefore, the calibration method of standard source is feasible. And this method was applied in calculating any shape sample. The integrality sphere source’s detection efficiency was consistent with the results of LabSOCS in 10%.