中国散裂中子源反角白光中子源束内伽马射线研究  

In-beam γ-rays of back-streaming white neutron source at China Spallation Neutron Source

作　　者：任杰[1] 阮锡超[1] 陈永浩 蒋伟 鲍杰[1] 栾广源 张奇玮[1] 黄翰雄[1] 王朝辉[1] 安琪 白怀勇[6] 鲍煜 曹平 陈昊磊 陈琪萍[7] 陈裕凯 陈朕[4,5] 崔增琪 樊瑞睿 封常青 高可庆[2,3] 顾旻皓 韩长材 韩子杰[7] 贺国珠 何泳成[2,3] 洪杨 黄蔚玲[2,3] 黄锡汝[4,5] 季筱璐[2,4] 吉旭阳[4,10] 江浩雨 姜智杰 敬罕涛[2,3] 康玲 康明涛 李波[2,3] 李超 李嘉雯 李论 李强 李晓[2,3] 李样 刘荣[7] 刘树彬 刘星言[7] 穆奇丽 宁常军[2,3] 齐斌斌 任智洲 宋英鹏[2,3] 宋朝晖 孙虹 孙康[2,3,9] 孙晓阳 孙志嘉[2,3,4] 谭志新 唐洪庆 唐靖宇[2,3] 唐新懿 田斌斌[2,3] 王丽娇 王鹏程 王琦 王涛峰 文杰 温中伟 吴青彪[2,3] 吴晓光[1] 吴煊 解立坤 羊奕伟 易晗[2,3] 于莉 余滔[4,5] 于永积[2,3] 张国辉[6] 张林浩[2,3,9] 张显鹏[8] 张玉亮[2,3] 张志永[4,5] 赵豫斌[2,3] 周路平[2,3,9] 周祖英[1] 朱丹阳[4,5] 朱科军[2,4,9] 朱鹏[2,3] Ren Jie;Ruan Xi-Chao;Chen Yong-Hao;Jiang Wei;Bao Jie;Luan Guang-Yuan;Zhang Qi-Wei;Huang Han-Xiong;Wang Zhao-Hui;An Qi;Bai Huai-Yong;Bao Yu;Cao Ping;Chen Hao-Lei;Chen Qi-Ping;Chen Yu-Kai;Chen Zhen;Cui Zeng-Qi;Fan Rui-Rui;Feng Chang-Qing;Gao Ke-Qing;Gu Min-Hao;Han Chang-Cai;Han Zi-Jie;He Guo-Zhu;He Yong-Cheng;Hong Yang;Huang Wei-Ling;Huang Xi-Ru;Ji Xiao-Lu;Ji Xu-Yang;Jiang Hao-Yu;Jiang Zhi-Jie;Jing Han-Tao;Kang Ling;Kang Ming-Tao;Li Bo;Li Chao;Li Jia-Wen;Li Lun;Li Qiang;Li Xiao;Li Yang;Liu Rong;Liu Shu-Bin;Liu Xing-Yan;Mu Qi-Li;Ning Chang-Jun;Qi Bin-Bin;Ren Zhi-Zhou;Song Ying-Peng;Song Zhao-Hui;Sun Hong;Sun Kang;Sun Xiao-Yang;Sun Zhi-Jia;Tan Zhi-Xin;Tang Hong-Qing;Tang Jing-Yu;Tang Xin-Yi;Tian Bin-Bin;Wang Li-Jiao;Wang Peng-Cheng;Wang Qi;Wang Tao-Feng;Wen Jie;Wen Zhong-Wei;Wu Qing-Biao;Wu Xiao-Guang;Wu Xuan;Xie Li-Kun;Yang Yi-Wei;Yi Han;Yu Li;Yu Tao;Yu Yong-Ji;Zhang Guo-Hui;Zhang Lin-Hao;Zhang Xian-Peng;Zhang Yu-Liang;Zhang Zhi-Yong;Zhao Yu-Bin;Zhou Lu-Ping;Zhou Zu-Ying;Zhu Dan-Yang;Zhu Ke-Jun;Zhu Peng(Key Laboratory of Nuclear Data,China Institute of Atomic Energy,Beijing 102413,China;Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China;Spallation Neutron Source Science Center,Dongguan 523803,China;State Key Laboratory of Particle Detection and Electronics,Beijing 100049,China;Department of Modern Physics,University of Science and Technology of China,Hefei 230026,China;State Key Laboratory of Nuclear Physics and Technology,School of Physics,Peking University,Beijing 100871,China;Institute of Nuclear Physics and Chemistry,China Academy of Engineering Physics,Mianyang 621900,China;Northwest Institute of Nuclear Technology,Xi’an 710024,China;University of Chinese Academy of Sciences,Beijing 100049,China;Department of Engineering and Applied Physics,University of Science and Technology of China,Hefei 230026,China;School of Physics,Beihang University,Beijing 100083,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 [2]中国科学院高能物理研究所,北京100049 [3]散裂中子源科学中心,东莞523803 [4]核探测与核电子学国家重点实验室,北京100049 [5]中国科学技术大学近代物理系,合肥230026 [6]北京大学物理学院,核物理与核技术国家重点实验室,北京100871 [7]中国工程物理研究院核物理与化学研究所,绵阳621900 [8]西北核技术研究所,西安710024 [9]中国科学院大学,北京100049 [10]中国科学技术大学工程与应用物理系,合肥230026 [11]北京航空航天大学物理学院,北京100083

出　　处：《物理学报》2020年第17期61-69,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11805282,11790321)资助的课题.

摘　　要：在基于白光中子源的中子核反应测量中,伴随中子束的伽马射线是重要的实验本底之一.本文对中国散裂中子源反角白光中子源的束内伽马射线进行了研究.通过蒙特卡罗模拟,得到了伽马射线的能量分布和时间结构.通过直接测量和间接测量两种方法测得低能中子区的束内伽马射线的时间结构.直接测量实验中,将载6Li的ZnS(Ag)闪烁体探测器置于束流线上,通过飞行时间法直接测量束内的中子和伽马射线的时间结构,并利用波形甄别技术进行粒子鉴别.间接测量法是将铅样品置于束流线上,利用C6D6闪烁体探测器测量样品上的散射伽马射线,从而得到入射伽马射线的时间结构.实验测量结果与模拟结果在12μs—2.0 ms的时间区间内具有较好的一致性.The back-streaming neutron beam line(Back-n)was built in the beginning of 2018,which is part of the China Spallation Neutron Source(CSNS).The Back-n is the first white neutron beam line in China,and its main application is for nuclear data measurement.For most of neutron-induced nuclear reaction measurements based on white neutron facilities,the beam of gamma rays accompanied with neutron beam is one of the most important experimental backgrounds.The back streaming neutron beam is transported directly from the spallation target to the experimental station without any moderator or shielding,the flux of the in-beam gamma rays in the experimental station is much larger than those of these facilities with neutron moderator and shielding.Therefore,it is necessary to consider the influence of in-beam gamma rays on the experimental results.Studies of the in-beam gamma rays are carried out at the back-n.Monte-Carlo simulation is employed to obtain the energy distribution and the time structure of the in-beam gamma rays.According to the simulation results,when the neutron flight time is longer than 1.0μs the energy distribution of the in-beam gamma rays does not vary with flight time.Therefore,the time structure of these gamma rays can be measured without the correction of the detection efficiency.In this work,the time structure of the in-beam gamma rays in the low neutron energy region is measured by both direct and indirect methods.In the direct measurement,a 6Li loaded ZnS(Ag)scintillator is located on the neutron beam line and the time of flight method is used to determine the time structure of neutrons and gamma rays.The gamma rays are separated from neutrons with pulse-shape discrimination.The black filter method is used to verify the particle discrimination results.In the indirect measurement,the C6D6 scintillation detectors are used to measure the gamma rays scattered off a Pb sample on the way of the neutron beam.The time structure of the in-beam gamma rays is derived from that of the scattered gamma rays.The ex

关 键 词：反角白光中子源 束内伽马射线测量 飞行时间法 蒙特卡罗模拟 

分 类 号：O571.53[理学—粒子物理与原子核物理]