中文摘要：

依据分段γ扫描装置（SGS）探测效率刻度理论，推导出探测器对单个光子探测效率计算公式，并分析了前置平板准直器对计算结果的影响，使用MCNP5软件建立探测装置模型，模拟了废物桶处在不同位置时，前置平板准直器两平板不同间距对高纯锗探测器相对计数率的影响，模拟结果表明：对于低密度物质，平板准直器适宜间距3．5 cm；对于中等密度物质，平板准直器适宜间距4 cm；对于密度较大物质平板准直器适宜间距4．5 cm。

英文摘要：

In this paper, through the analysis of sub -scale theory of detection efficiency of the gamma scanning device （SGS）, calculated the single photon detection efficiency formula , and analyzed the front plate collimator using MCNP5 software detection devices model calculations , simulated waste barrel in a different position , and tabled different spacing of the front plate collimator for high -purity germanium detector count rate , the simula-tion results show that：suitable for low-density material, flat collimator spacing is 3.5 cm;for medium-den-sity substances, collimator suitable spacing is 4 cm;suitable for higher density material flat collimator spacing is 4.5 cm.