CSNS带宽限制中子斩波器系统性能研究  

Research on system performance of a bandwidth limiting neutron chopper at CSNS

作　　者：王闪闪 蔡伟亮 王平[2,3] 张鸿 左太森[2,3] 王松林[2,3] WANG Shanshan;CAI Weiliang;WANG Ping;ZHANG Hong;ZUO Taisen;WANG Songlin(College of Physics and Optoelectronic Engineering,Shenzhen University,Shenzhen 518060,China;Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China;Spallation Neutron Source Science Center,Dongguan 523803,China)

机构地区：[1]深圳大学物理与光电工程学院,深圳518060 [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

出　　处：《核技术》2021年第2期23-29,共7页Nuclear Techniques

基　　金：国家自然科学基金(No.U1932163);中国科学院青年创新促进会(No.2016014)资助。

摘　　要：带宽限制中子斩波器是飞行时间型中子散射谱仪上的重要设备之一,其性能的优劣影响着谱仪的测试效率。依靠周期性转动的转盘,带宽限制中子斩波器可用于中子波长范围的选择和脉冲周期重叠背底的滤除,提高信噪比。基于安装在中国散裂中子源(China Spallation Neutron Source,CSNS)通用粉末衍射仪上的带宽限制中子斩波器系统,结合理论计算、McStas软件模拟及中子束流实验方法,对带宽限制中子斩波器的性能进行了系统的研究。结果表明:带宽限制中子斩波器实际选择的波长带宽约为0.478 nm,与目标带宽0.48 nm的相对误差在0.5%以内,具有显著滤除长波背底的效果;验证了安装在CSNS散射谱仪上的带宽限制中子斩波器的性能满足工程需求,也可为即将建设的中子散射谱仪上带宽限制中子斩波器的设计与改进提供参考。[Background]Bandwidth limiting(BWL)neutron chopper is one of the important devices installed on the time-of-flight neutron scattering spectrometer.The BWL chopper can select the wavelength range of neutrons and filter the pulse period overlapping background by means of the periodically rotating disk,so as to improve the signalto-noise ratio.[Purpose]This study aims to verify whether the performance of the BWL choppers installed on the neutron scattering spectrometer of China Spallation Neutron Source(CSNS)meets the engineering requirements;on the other hand,it can provide reference for the design of BWL chopper on to be constructed.[Methods]First of all,based on the BWL chopper system installed on the general purpose powder diffractometer(GPPD)of CSNS,the performances of the BWL chopper were systematically studied by theoretical calculation.Then,Monte Carlo simulation software McStas was employed to calculate the performance of BWL with the physical parameters of neutron choppers.Finally,neutron beam experiments were carried out to measure the actual working performance of the BWL choppers.[Results]The results show that the actual wavelength bandwidth is about 0.478 nm with less than 0.5%relative error to the target bandwidth of 0.48 nm.The BWL chopper has a significant effect on the filtering longwave neutron background.[Conclusions]The BWL neutron chopper installed on GPPD of CSNS satisfies engineering needs,and can provide a reference for the design and improvement of the BWL in the neutron scattering spectrometer to be built in the future.

关 键 词：带宽限制中子斩波器 转盘 McStas 中子束流实验 

分 类 号：TL99[核科学技术—核技术及应用]