用于裂变瞬发中子谱测量的平行板雪崩计数器研制及性能测试  

Development of parallel plate avalanche counters for prompt fission neutron spectrum measurement

作　　者：朱意威 黄翰雄[1] 杨贺润[2] 王学浩 任杰[1] 段利敏[2] 张俊伟 孙琪 阮锡超[1] ZHU Yiwei;HUANG Hanxiong;YANG Herun;WANG Xuehao;REN Jie;DUAN Limin;ZHANG Junwei;SUN Qi;RUAN Xichao(Key Laboratory of Nuclear Data,China Institute of Atomic Energy,Beijing 102413,China;Institute of Modern Physics,Chinese Academy of Sciences,Lanzhou 730000,China;China West Normal University,Nanchong 637002,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]中国科学院近代物理研究所,兰州730000 [3]西华师范大学,南充637002

出　　处：《核技术》2021年第12期55-62,共8页Nuclear Techniques

基　　金：科技部国家重点研发计划项目(No.2016YFA0401603);国家自然科学基金面上项目(No.11975318)资助。

摘　　要：裂变瞬发中子谱(Prompt Fission Neutron Spectrum,PFNS)是重要的核反应数据,为了测量低于源中子能量的裂变瞬发中子谱,通常是用中子探测器与平行板雪崩计数器(Parallel Plate Avalanche Counters,PPAC)进行符合测量以扣除非裂变事例的影响。针对裂变瞬发中子谱测量的需求,研制了一个由10个单元组成的PPAC。用Maxwell软件模拟了相同尺寸及工作条件下丝状电极电离室和平板电极电离室的电场分布。对该PPAC的结构及其性能测试进行了详细介绍。该PPAC工作于低气压流气模式,每个单元可以独立工作。该PPAC测试的结果为相邻两个PPAC单元之间的时间符合谱半高宽(Full Width at Half Maximum,FWHM)为620 ps,PPAC与液体闪烁体探测器的时间符合谱γ峰的半高宽为880 ps。测试结果表明:该PPAC的时间响应快,达到预期指标,适合用于高事例率情况下的时间符合测量。[Background]The prompt fission neutron spectrum (PFNS) is an important nuclear reaction data.Coincident measurement between neutron detectors and parallel plate avalanche counters (PPAC) is widely used to measure the PFNS below the energy of the neutron source,hence most of the non-fission neutrons can be exclude.[Purpose]This study aims to develop a PPAC to satisfy the PFNS measurement and performance test.[Methods]First of all,a ten-cell PPAC was designed with low-pressure flow working gas and individual cell functionality.Then the software named"Garfield"was used to simulate the distributions of electric field of two kind of fission chambers,i.e.,wire-electrode chamber and plate-electrode chamber,under the same geometric dimensions and working conditions.Finally,the structure and the performance of the PPAC were introduced in detail,and relevant performance of this PPAC was tested by experiment.[Results]The full width at half maximum (FWHM) of the timecorrelated spectrum between two neighbor cells using a;Amαsource is 620 ps.The FWHM of the time-correlated spectrum between a PPAC cell and a liquid scintillator detector is 880 ps using a;Cf fission source.[Conclusions]The experiment confirms that the time resolution of the designed PPAC is good enough for high event rate measurements.

关 键 词：平行板雪崩计数器 裂变瞬发中子谱 符合测量 中子谱 时间响应 

分 类 号：TL81[核科学技术—核技术及应用]