掺钆液闪探测器用于锦屏地下实验室的快中子本底测量  

Fast neutron background measurement at the China Jinping laboratory with a gadolinium-doped liquid scintillator detector

作　　者：王桢 何汉涛 刘书魁[3] 林兴德[3] 幸浩洋[3] 朱敬军[1] WANG Zhen;HE Han-Tao;LIU Shu-Kui;LIN Xing-De;XING Hao-Yang;ZHU Jing-Jun(Key Laboratory of Radiation Physics and Technology of the Ministry of Education,Institute of Nuclear Science and Technology,Sichuan University,Chengdu 610064,China;China Institute of Atomic Energy,Beijing 102413,China;College of Physics,Sichuan University,Chengdu 610064,China)

机构地区：[1]四川大学原子核科学技术研究所辐射物理及技术教育部重点实验室,成都610064 [2]中国原子能院,北京102413 [3]四川大学物理学院,成都610064

出　　处：《四川大学学报（自然科学版）》2021年第4期117-124,共8页Journal of Sichuan University(Natural Science Edition)

基　　金：国家自然科学基金(11275134);清华大学粒子技术与辐射成像教育部重点实验室项目(20151202)。

摘　　要：文章采用掺杂0.5%Gd液闪探测器测量了中国锦屏地下实验室(CJPL)的快中子本底通量及中子能谱.掺钆液闪探测器对于核反冲信号和电子反冲信号优异的甄别性能用于中子候选事例的筛选,并采用钆对热中子的俘获特性进行时间甄别.对有效采数时间为206 d的数据进行分析,获得锦屏地下实验室的聚乙烯室(PE)内1~10 MeV快中子通量为4.45×10^(-8)cm^(-2)·s^(-1).采用相似的方式分析了掺钆液闪探测器(Gd-Ls)中天然放射系的α本底程度,来源于^(238)U,^(235)U,^(232)Th的α粒子含量分别为(0.0227±0.0001)s^(-1),(0.0329±0.0001)s^(-1)和(0.1471±0.0002)s^(-1).与世界上其他深地实验室的快中子通量进行对比,CJPL的快中子通量处于极低水平,是进行稀有事例测量实验的理想场所.We report the fast neutron flux and spectrum in the PE room at the China Jinping Underground Laboratory(CJPL)with a liquid scintillator detector doped with 0.5%gadolinium(Gd-Ls).The difference between nuclear recoil signals and electronic recoil signals is used to select neutron events in a liquid scintillator detector doped with gadolinium.The signature of gadolinium-captured thermal neutrons is used to time discrimination.The fast neutron flux range of 1~10 MeV measured in the PE room at the CJPL is 4.45×10^(-8)cm^(-2)·s^(-1)based on 206 days of data.A similar selection method is used to analyze the degree ofαcontamination in the Gd-Ls.Theαcontamination of the natural radioactivity series including^(238)U,^(235)U,and^(232)Th are(0.0227±0.0001)s^(-1),(0.0329±0.0001)s^(-1),and(0.1471±0.0002)s^(-1),respectively.Compared with the fast neutron flux of other deep laboratories around the world,the fast neutron flux of CJPL is at an extremely low level,which is an ideal place for rare-events measurement experiments.

关 键 词：CJPL 暗物质 快中子 粒子甄别 α本底 掺钆液闪探测器 

分 类 号：TL812.2[核科学技术—核技术及应用]