HPGe γ谱仪体源效率与源高度和密度的关系

Relationship of the HPGe γ-Spectrometer Detection Efficiency with Sample Height and Density

用γ谱仪分析环境样品时,常遇到样品高度和样品密度与刻度标准体源不一致的情况,通常的方法是分别给出体源效率与样品高度和样品密度的拟合公式,这在实际应用中很不方便.作者使用一个统一的二元二次多项式拟合公式,以描述体源探测效率与样品高度和样品密度的关系,并用经实验验证且由蒙特卡罗方法计算出的一组效率、高度、密度数据,对其高度范围从9～70mm,密度范围从0.4～1.6g/cm3,所相应的拟合公式进行了验证,其复相关性达到0.99992,最大相对残差小于0.7%.

The inconsistency between the being detected sample and the standard sample in height and density is often encountered when the radioactivity of environment sample is analyzed by γ spectrum. The existent method for solving this problem is by giving the relationship between the detection efficiency and sample height and the relationship between the efficiency and the density respectively. In order to overcome the inconvenience of this method, tha authors have provided the unite fit formula which using binomial of two independent variable to describe the relationship of efficiency with the sample height and the density.The validity of this formula has been verified by Monte Carlo method. The multi correlation coefficient obtained to (0.99992.) The maximal relative difference between fit value and MC calculated value was less than 0.7%.