用于(n,2n)反应截面测量的3He管阵列设计  

Design Schemes of 3He Tube Array for(n,2n)ReactionCross Section Measurement

作　　者：王朝辉[1] 于伟翔[1] 陈雄军[1] 江历阳[1] 李景文[1] 陈建琪 阮锡超[1] WANG Zhao-hui;YU Wei-xiang;CHEN Xiong-jun;JIANG Li-yang;LI Jing-wen;CHEN Jian-qi;RUAN Xi-chao(Key Laboratory of Nuclear Data,China Institute of Atomic Energy,Beijing 102413,China)

机构地区：[1]中国原子能科学研究院核数据重点实验室,北京102413

出　　处：《现代应用物理》2020年第1期40-45,共6页Modern Applied Physics

基　　金：国家自然科学基金资助项目(11375275)。

摘　　要：为设计适用于符合法测量(n,2n)反应截面的3He管阵列探测系统,利用粒子输运蒙特卡罗模拟程序MCNP,计算了柱形排列和球形分布两种方案下3He管阵列探测系统的探测效率随中子能量的变化曲线。结果表明,柱形排列虽然探测效率较高,但内外层3He管的探测效率差别较大,整体探测效率随能量有明显变化,引起测量结果的不确定度增大;球形分布3He管的探测效率随能量变化不大,故选用了以聚乙烯为慢化体的3He管球形分布方案。同时,对3He球进行了细化设计,给出了中子不同出射方向分布下的探测效率随中子能量的变化曲线。此外,还设计了包含110根3He管的阵列探测器系统,计算了该系统的探测效率随中子能量的变化关系。结果表明,此系统可以用于符合法测量(n,2n)反应截面。To design a 3He tube array detection system suitable for measuring(n,2n)reaction cross section by coincidence method,two design schemes of the column arrangement and the sphere distribution are simulated by using a general Monte Carlo N-particle transport code(MCNP),and the detection efficiency of 3He tube array detection system with the change of neutron energy is calculated.The results show that the detection efficiency of the inner and outer 3He tubes varies greatly,and the overall detection efficiency varies with the energy.The detection efficiency of 3He tube with sphere distribution varies little with energy,so the sphere distribution scheme of 3He tube with polyethylene as moderator is selected.At the same time,the refinement design of 3He sphere is carried out,and the detection efficiency with the neutron energy under different direction distributions is given.In addition,an array detector system with 1103He tubes is designed,and the relationship between the detection efficiency and the neutron energy is calculated.The results show that this system can be used to measure the(n,2n)reaction cross section by coincidence method.

关 键 词：3He管阵列 中子探测器 探测效率 符合测量 蒙特卡罗模拟 

分 类 号：O571.5[理学—粒子物理与原子核物理]