【摘要】 在环境样品放射性测量中,探测效率越高,在达到同样精度的情况下,可以减少测量时间,从而提高谱仪的利用率。圆柱形环境样品的几何形状大小对探测效率有一定的影响。为了寻找相同体积的圆柱型样品具有最佳探测效率时的半径和高度值,本文利用MCNP-4B程序对相同体积不同圆柱形大小的土壤样品进行了模拟,然后再与实验测量两种样品在四种不同尺寸时的探测效率进行对比和检验。模拟和实验检验结果发现,目前采用的约Φ7.5cm×7.5cm规格样品其探测效率并非最佳,而是约Φ12cm×3cm规格时的探测效率最佳,与前者相比效率可以提高大约20%以上。更多还原

【Abstract】 In the radioactive measurements of environmental samples, if a constant measurement accuracy is required, the higher the detection efficiency, the less measurement time and the higher utilization ratio of the spectrometer. For the same sample volume, the shape of cylindric samples may affect the detection efficiency. The detection efficiencies of cylindric samples with the same volume but variable shapes have been simulated with MCNP-4B, and verified by experiments. It is shown that efficiency of the cylindric sample with a size of Φ12m×3cm is the highest, which is about 20% higher than that for general cylindric samples with a size of Φ7.5cm×7.5cm.更多还原