中文摘要：

为满足脉冲中子探测系统对辐射屏蔽的要求，在利用MCNP程序模拟计算准直孔分别为圆柱形直孔和锥形孔的屏蔽效果基础上，设计了圆柱形直孔＋锥形孔的准直器结构，准直器采用铁35 cm厚＋聚乙烯20 cm厚＋铅15 cm厚的组合材料。理论计算表明：该准直器用于反冲质子探测系统时，探测系统输出信号与干扰信号的比值大于10。

英文摘要：

It is very important to design collimator to reduce the radiation background.A collimator design for a pulsed neutron flux measurement to reduce background is investigated in this paper.The shading effects of round shaded hole and coned-shaded hole have been simulated by MCNP.The collimator structure,which is a combination of round shaded hole and coned-shaded hole,has been design to be composed of a combination of 35 cm thick iron,20 cm thick polyethylene and 15 cm thick lead.The ratio of signal current and background current is calculated to be larger than 10 when this collimator is used for the recoil proton detection system.