用于裂变中子注量测量的高气压4He气体闪烁体探测器技术研究

γ射线干扰已成为制约临界装置上基准实验不确定度进一步降低的首要因素，亟需中子-伽马射线甄别比高、响应时间快且探测效率较高的新型中子探测器。利用4He气体原子序数低、闪烁光输出值大、n-γ波形甄别容易、响应时间快、裂变中子弹性散射截面高的优点，可研制基于4He气体的气体闪烁体探测器。同时，利用提高4He气压的方法可大幅提高其探测效率。因此，基于高气压4He气体的气体闪烁体探测器有望满足临界装置上精密物理实验对低伽马敏感度新型探测器的需求。本项目将重点解决探测器物理设计、探测器制备及高效n-γ甄别等关键技术问题，从而发展针对强伽马本底下裂变中子注量探测的低伽马敏感度新型探测器技术。基于高气压4He的气体闪烁体探测器具有n-γ甄别比高、响应时间快、探测效率高、无需慢化体的特点，可应用于临界装置上基准实验、乏燃料监测、特殊核材料识别等场景。

Gamma radiation accompanied with the fission neutrons has limited the measurement uncertainty of benchmark experiments performed on critical assemblies. Hence novel neutron detectors with high n-γ rejection ratio, fast response and relatively high detection efficiency are demanded. High-pressure 4He scintillation detectors benefit from helium’s low Z-number, large light output per deposited energy, n-γ pulse shape discrimination, fast response, and large elastic scattering cross section with fission neutrons. Moreover, neutron detection efficiency can be enhanced with high pressure 4He. Consequently, high-pressure 4He scintillation detectors are highly desirable for applications in fission neutron detection. Our study will focus on the detector design, fabrication, and n-γ discrimination. High-pressure 4He scintillation detectors are expected to be usable for neutron detection in intense neutron/gamma mixed field, such as neutron fields of critical assemblies, spent fuel, special nuclear material, etc.