平板高纯锗探测器几何参数修正的解析方法
Analytic Method for Geometrical Parameter Correction of Planar HPGe Detector
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摘要: 本文推导了1个用于计算平板高纯锗探测器对点源发射光子的探测效率的数值积分公式，并应用此积分公式进行了高纯锗探测器的几何参数修正。将241Am、137Cs点源分别置于平板探测器前端的不同距离（1~20 cm）处进行实验测量，以探测效率的实验结果为拟合真值，利用积分公式通过加权最小二乘拟合获得该探测器的几何参数。将修正后的参数应用于MCNP模拟计算，对59.5及661.6 keV光子，在1~20 cm探测距离范围内，探测效率的模拟值与实验值之间的相对偏差<1%。研究表明，此解析方法实现了对探测器几何参数的快速修正，结果准确可靠。Abstract: A numerical integration formula was introduced to calculate the response of planar HPGe detector to photons emitted from point source. Then the formula was used to correct the geometrical parameter of planar HPGe detector. 241Am and 137Cs point sources were placed at a certain distance (1-20 cm) away from entrance window to get the corresponding detection efficiency. The detection parameters were calculated in weighted least square fitting using the formula with the experimental efficiencies as formula results. This correction method was accurate and timesaving. The simulation result from MCNP using the corrected parameters shows that the relative deviations between simulation and experimental efficiencies are less than 1% for 59.5 and 661.6 keV photons with the distance of 1-20 cm.
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Keywords:
- planar HPGe ,
- Monte Carlo ,
- numerical integration ,
- weighted least square
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