摘要
金刚石材料具有优异的耐高温、抗辐照性能,用其制作的辐照探测器在反应堆等苛刻环境下具有很好的应用前景。在分析金刚石中子探测器的结构和工作原理的基础上,使用MCNP(Monte Carlo N Particle Transport Code)模拟程序构建了金刚石中子探测器的物理模型,考虑探测器用于2 MWt液态燃料钍基熔盐试验堆(Thorium Molten Salt experimental Reactor-Liquid Fueled,TMSR-LF1)辐射场中,计算中子转换层(6LiF、10B)厚度、金刚石厚度、γ甄别阈值对探测器的中子探测效率、γ探测效率以及n/γ抑制比的影响。结果表明:6LiF更适合在中子、γ混合场中用作中子转换层;随着6LiF厚度增加,中子探测效率先增大后减小,6LiF的最优厚度为25μm;金刚石厚度增大会导致探测器的n/γ甄别性能下降,可以采用设置γ甄别阈值的方法解决金刚石层过厚时带来的γ干扰过大的问题,使探测器达到对γ不灵敏的要求。模拟研究工作获得了探测器结构参数对探测器性能的影响规律,对探测器后续的制作和研究具有指导意义。
[Background]Diamond material demonstrates excellent temperature and radiation resistance properties,and detectors made from diamond exhibit good potential for use under harsh environments.[Purpose]This study aims to analyze the structure and working principle of diamond thermal neutron detectors,and establish a physical model of such a detector applied to 2 MW thorium molten salt experimental reactor-liquid fueled(TMSR-LF1)radiation field by using MCNP program.[Methods]First of all,6Li and 10B were selected as neutron conversion materials considering the neutrons of TMSR-LF1 mainly concentrated in the 10-8~10-6 MeV energy range,and the Stopping and the Range of the Ions in Matter(SRIM)program was employed to calculate the range of secondary charged particles generated by the reaction in the neutron conversion layer and diamond layer.Then,the MCNP program was used to establish a physical model of diamond neutron detector applied to 2 MW TMSR-LF1 radiation field.Finally,the effects of the neutron conversion layer thickness(6LiF,10B),diamond thickness,andγscreening threshold on the neutron detection efficiency,γdetection efficiency,and n/γsuppression ratio of the detector were determined through simulation results.[Results]The results reveals that 6LiF is more suitable than 10B for use in the neutron conversion layer in neutron andγmixed fields.With the increase of the 6LiF thickness,the neutron detection efficiency first increases and then decreases,and the optimal thickness of 6LiF is 25μm.The n/γdiscrimination performance of the detector deteriorates with the increase of diamond thickness,but the diamond thickness must be greater than 20μm to ensure insensitivity of the detector toγ,hence aγscreening threshold is needed to prevent excessiveγinterference for thick diamond layers.[Conclusion]The influence of detector structural parameters on detector performance obtained by this study has guiding significance for the subsequent fabrication of and research on such detectors.
作者
任欢
张志宏
夏晓彬
蔡军
REN Huan;ZHANG Zhihong;XIA Xiaobin;CAI Jun(Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Shanghai 201800,China;China University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《核技术》
CAS
CSCD
北大核心
2023年第7期61-68,共8页
Nuclear Techniques
基金
中国科学院青年创新促进会项目(No.2021256)资助。
