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即将建成的中国散裂中子源(China Spallation Neutron Source,CSNS)反角白光中子束线可为核数据测量提供高注量率的脉冲白光中子束流,填补我国核数据测量用白光中子源的空白,提高我国核数据测量水平,满足核能、核技术及基础核物理研究对核数据的需求。该束线建成后,其中子能谱及注量率的精确测量将是开展其它物理实验的基础,快裂变电离室因其独特优点被选为中子能谱和注量率测量探测器。通过实验研究了快裂变电离室的粒子分辨性能、时间分辨性能;确定阴、阳极的合理间距为10 mm,据此测得电离室的时间分辨约15 ns;利用235U样品量计算的探测效率与利用伴随粒子法给出的探测效率在不确定度范围内符合,因此可以标定快裂变室的探测效率。通过这些工作,完成了满足反角白光中子束能谱及注量率测量需求的快裂变室的物理设计。
The soon to be completed China Spallation Neutron Source (CSNS) contra-angle white neutron beam can provide a pulsed white-light neutron beam with high fluence for nuclear data measurement and fill the white light for nuclear data measurement in China The source of blank, to improve China’s nuclear data measurement to meet the nuclear energy, nuclear technology and basic nuclear physics research on nuclear data needs. After the beamline is completed, the accurate measurement of its neutron energy spectrum and fluence rate will be the basis for other physical experiments. The fast-fission ionization chamber is selected as the neutron energy spectrum and fluence rate measurement detector because of its unique advantages. The particle resolution and time resolution of the fast-fission ionization chamber were experimentally studied. The reasonable interval between anode and cathode was determined to be 10 mm. The time resolution of the ionization chamber was about 15 ns. The detection efficiency The probing efficiency given by the concomitant particle method fits within the uncertainty range so that the detection efficiency of fast fission chambers can be calibrated. Through these efforts, the physical design of a fast fission chamber that meets the requirements of the contra-angle white neutron beam spectroscopy and fluence measurement has been completed.