强激光与粒子束2017，Vol.29Issue(12)：143-148,6.DOI:10.11884/HPLPB201729.170232
(n,2n)反应实验研究中的中子准直器设计
Neutron collimator design for experimental study of (n,2n) reaction cross section
摘要
Abstract
(n,2n) cross section can be measured through the direct measurement method with a 4π spherical 3 He neutron detector.The neutron beam must be collimated in such experiments.A satisfactory design of the collimator is required to:(1)improve the uniformity of neutron flux at sample position and guarantee enough decreasing amplitude of the border of neutron beam at the same time;(2) reduce the scattered neutron background at low energy region.In this work,using FLUKA and MCNPX codes,the comparison between cylindrical collimator,conical collimator,and three double-truncated conical collimators with different slope on the uniformity of neutron flux and the proportion of low energy neutron was studied.The result shows that the double-truncated conical collimator with low slope can satisfy the experiment requirement.At the same time,the response of the detection system was compared after neutrons collimated by five collimators respectively with and without sample.The result shows that when neutrons are collimated by the double-truncated conical collimator with low slope,the detection system has the higher count rate with sample,and the lower background without sample.In addition,the collimation efficiency affected by the slope of collimator outlet was also compared.The double-truncated conical collimator with low slope was finally chosen as the neutron collimator and the materials of the collimator are red copper,stainless steel,polyethylene and lead.The diameter at the beginning of the collimator aperture is 2.64 cm and its length is 137 cm.The beam diameter after collimation at the sample position is 3.2 cm.关键词
准直器/蒙特卡罗模拟/(n,2n)反应截面/中子注量率/低能中子所占份额/直接测量Key words
collimator/Monte Carlo simulation/measurement of (n,2n) cross section/neutron flux/percentage of low energy neutron/direct measurement分类
数理科学引用本文复制引用
陈建琪,陈雄军,阮锡超,于伟翔,任杰..(n,2n)反应实验研究中的中子准直器设计[J].强激光与粒子束,2017,29(12):143-148,6.基金项目
核数据专项基金项目(JCKY201620113001) （JCKY201620113001）
