In the radioactive measurement of environment sample with HPGe detector, it is evident that the higher detection efficiency, the less measurement time and the more spectrometer's utilization. For the same sample volume, the shape of environment sample may affect the detection efficiency. The detection efficiency of environment samples which filled in different shapes for saddle-like sample boxes with the same volume was simulated with MCNP code, and the optimum shape was found and demonstrated by experiments. Results of both experiments and simulations show that the detection efficiency of the optimum shape for saddle-like sample box is twice higher than that of cylinder sample.%在HPGe探测器测量环境样品放射性时,探测效率越高,测量时间越短,谱仪的利用率也越高.对一定体积的体源样品,几何形状对探测效率有较大影响.本文利用MCNP程序对同体积的不同马鞍形环境样品进行了模拟,寻找出了最佳马鞍形样品形状,并进行了实验验证.模拟和实验结果表明,最佳马鞍形样品与目前常用的圆柱形样品相比,其探测效率可提高1倍以上.
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