大空间覆盖高集成度闪烁体中子探测器关键性能研究

Neutron scattering techniques are playing an important role in the study of material structure and dynamic properties, which are widely used in various subjects. The neutron scattering spectrometers for China advanced research reactor (CARR), Chinese spallation neutron source (CSNS) and other large neutron science devices require the neutron detector with large area-covered, high integration，high detect efficiency and high position resolution,etc. 3He neutron detector is an ideal one for many neutron spectrometers. However, due to the shortage of 3He gas and the rapidly increasing price, seeking new neutron detectors to replace 3He neutron detector are urgent. The advantages of scintillator detector, including high efficiency, high position resolution, low n/γ rejection ratio, real-time detecting and so on, make it suitable for many neutron instruments which need large area-covered and high integration neutron detectors. .The investigation of the scintillator neutron detector includes: using two layers of oblique incidence 6LiF/ZnS(Ag) scintillator as the neutron convertor; the wavelength-shifting fibers (WLSFs) are used to collect the luminescent lights; the Silicon- photomultiplier tube(Si-PM) is chosen for photoelectric conversion; the fast ASIC electronics and data acquisition system are designed for in-time neutron detect. .The coupling optical path of the scintillator and the wavelength-shifting fibers, and the configuration of the wavelength-shifting fibers array will be studied. The compact construction of the detector will be designed to fulfill the small dead area, high detect efficiency and high spatial resolution. The key technologies will be grasped though the R&D of this detector, which will be used in the volume production in future. The large area-cover and high integration make the scintillator detector be a good alternative detector for the future neutron scattering instruments.

中子散射技术是研究物质结构和动力学性质的理想探针，已在众多学科领域研究中被广泛应用。随着中国先进研究堆(CARR)和中国散裂中子源(CSNS)等大型中子科学装置的建成, 大量中子散射谱仪要求其中子探测器系统能够实现大空间大立体角覆盖、高集成度、高性能的实时快速探测。传统的3He型探测器由于价格高昂，研制新型大面积阵列型中子探测器迫在眉睫。利用中子敏感闪烁材料和波移光纤结构的位敏型中子探测器是目前国际上用于替代3He型中子探测器的研究热点。本项目研究的大空间覆盖位敏型闪烁体中子探测器, 利用斜入射结构的双层中子敏感闪烁屏，配套专用ASIC电子学及数据获取系统，实现对热中子的高效率、高分辨率、实时探测。该探测器同时还具有小死区、可快速拼接等优点，实现批量生产后未来可以在中子谱仪上大面积推广使用，很好解决未来国内新一代中子源上中子谱仪对大空间立体角覆盖的高集成中子探测器的需求。

中子散射技术是研究物质结构和动力学性质的理想探针，已在众多学科领域研究中被广泛应用。随着中国先进研究堆(CARR)和中国散裂中子源(CSNS)等大型中子科学装置的建成, 大量中子散射谱仪要求其中子探测器系统能够实现大空间大立体角覆盖、高集成度、高性能的实时快速探测。传统的3He型探测器由于价格高昂，研制新型大面积阵列型中子探测器迫在眉睫。本项目研究的大空间覆盖位敏型闪烁体中子探测器, 利用斜入射结构的中子敏感闪烁屏，光电信号转换采用高性能、高集成和低成本的硅光倍管（Si-PM），配套专业低功耗高集成度的ASIC电子学及数据获取系统，最终实现探测器高探测效率、高位置分辨、小死区、可大面积拼接的优异性能。本项目首先利用MC模拟实现对探测器中的光子输运过程的跟踪，通过修改探测器单元的关键物理参数得到合理的光路设计参数，之后结合探测器关键器件性能测试结果，修正模拟，最终得到探测器的最佳设计参数，并通过对探测器样机的制作和性能研究，掌握闪烁体与光纤阵列的排布、固定, 硅光倍管阵列的封装，光纤转弯及其端面与硅光倍管阵列的耦合等关键技术难题，并试制出用于硅光倍管阵列读出的专用ASIC电子学。 探测器样机的最终测试结果表明，探测器面积为25cm×50cm，热中子探测效率好于40％@2 Å，位置分辨达为4mm×4mm，所有指标均满足最初的物理设计指标。该探测器还具有小死区、可快速拼接等优点，实现批量生产后未来可以在中子谱仪上大面积推广使用，很好解决未来国内新一代中子源上中子谱仪对大空间立体角覆盖的高集成中子探测器的需求。