基于气体电子倍增器的位置灵敏快中子探测器优化设计  

Optimal design of the position sensitive fast neutron detector based on GEM

作　　者：魏阳东 周健荣 周晓娟[2,3] 朱林 周建晋[2,3,4] 许虹 杨桂安 王小胡 孙志嘉[2,3] 陈元柏 WEI Yangdong;ZHOU Jianrong;ZHOU Xiaojuan;ZHU Lin;ZHOU Jianjin;XU Hong;YANG Guian;WANG Xiaohu;SUN Zhijia;CHEN Yuanbo(Fundamental Science on Nuclear Waste and Environmental Security Laboratory,Southwest University of Science and Technology,Mianyang 621900,China;Spallation Neutron Source Science Center,Dongguan 523803,China;State Key Laboratory of Particle Detection and Electronics,Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China;School of Nuclear Science and Technology,Lanzhou University,Lanzhou 730000,China)

机构地区：[1]西南科技大学核废物与环境安全国防重点学科实验室,绵阳621900 [2]散裂中子源科学中心,东莞523803 [3]中国科学院高能物理研究所核探测与核电子学国家重点实验室,北京100049 [4]兰州大学核科学与技术学院,兰州730000

出　　处：《核技术》2021年第2期43-48,共6页Nuclear Techniques

基　　金：国家重点研发计划(No.2017YFA0403702);国家自然科学基金(No.U1832119、No.11635012、No.11775243);中国科学院青年创新促进会、核废物与环境安全国防重点学科实验室开放基金(No.16kfhk05);广东省基础与应用基础研究基金(No.2019A1515110217)资助。

摘　　要：采用聚乙烯转换层的气体电子倍增器(Gas Electron Multiplier,GEM)探测器具有快中子探测、较高时间分辨及位置分辨等性能,能很好地满足中国散裂中子源(Chinese Spallation Neutron Source,CSNS)大气中子谱仪束流监测的需求。采用蒙特卡罗仿真软件Geant4(GEometry ANd Tracking,version 4)对探测器的物理过程进行模拟,研究7 MeV、10 MeV、14 MeV三种不同能量中子的探测效率与聚乙烯转换层厚度的关系;并研究不同厚度阻止层对反冲质子出射能量、角度以及探测器探测效率的影响。此外模拟计算了反冲质子在不同厚度气体中的能量沉积以及探测器的γ射线灵敏度。最后根据模拟参数制作探测器样机并进行了初步的中子束流实验。实验结果表明:探测器采用2 mm聚乙烯转换层、200μm铝阻止层以及4 mm工作气体时,探测器具有良好的二维成像能力,位置分辨率可达2.9 mm。[Background]The GEM(gas electron multiplier)detector with polyethylene conversion layer has the performance of fast neutron detection,high timporal resolution and spatial resolution.It is an ideal choice for fast neutron beam monitor for China spallation neutron source(CSNS).[Purpose]This study aims to optimize the design of the GEM detector with polyethylene to meet its application requirements of the atmospheric neutron spectrometer of CSNS.[Methods]First of all,the physical process of the detector was simulated by Monte Carlo simulation software Geant4(GEometry ANd Tracking,version 4).The relationship between neutron detection efficiency of three different energies(7 MeV,10 MeV and 14 MeV)and the thickness of polyethylene conversion layer was studied by simulation,and the influences of different thickness of barrier layer on energy and angle of recoil proton along with detection efficiency were investigated.Then,the energy deposition of recoil protons in gas with different thickness was calculated,and theγ-ray sensitivity of the detector was studied by simulation.Finally,the prototype detector was fabricated using simulated parameters,and a preliminary neutron beam experiment was carried out.[Results]The results show that the detection has good two-dimensional imaging ability when the detector adopts 2 mm thick polyethylene,200μm thick aluminium barrier layer and 4 mm thick working gas.The spatial resolution of this detector can reach 2.9 mm.[Conclusions]This GEM based neutron detector meets the requirements of CSNS beam monitoring,which provides a reference for the optimal design of fast neutron beam monitor.

关 键 词：GEM 快中子 位置分辨 束流监测 

分 类 号：TL99[核科学技术—核技术及应用]