基于涂硼转换体的He3替代中子探测器研究

涂硼气体中子探测器是一种受到广泛关注的He3替代探测器。在此类探测器中，大的比表面积是获取高本征探测效率的前提，因此多数方案都在探测器内设置了大量细径长丝的正比管阵列来实现中子探测，以大量阳极丝倍增、收集10B（n，α）7Li反应后电离产生的电子。这不仅增加了制造工艺的难度，也降低了探测器的工作可靠性。本申请提出基于涂硼蜂窝转换体的中子探测器实现方案，通过引入电子漂移机制，使10B（n，α）7Li反应后电离产生的电子迁移出中子转换体，在外置位敏电子倍增器处再进行倍增。由此可在保持较高热中子探测效率的基础上显著降低探测器制备复杂度、改善工作可靠性并获得mm量级的位置分辨率。此外，本方案还具有出色的中子方向敏感性和串扰中子抑制能力，可将本底中子计数降低一个量级，提升探测系统的信本比。在预研验证的基础上，本项目将继续研究其中的核心物理技术问题，以获得一种在中子散射领域可用的3He替代探测器。

Boron-lined gaseous detectors play the important role as the 3He alternative detectors in the neutron scattering and homeland security. However, due to the short range of alpha particle or 7Li nucleus, the large S/V (surface area vs volume) ratio is the necessity for achieving a high intrinsic neutron detection efficiency. Most of the researchers thus place tremendous anode wires inside the detector’s sensitive volume to multiply the ionized electrons after the 10B（n，α）7Li reaction. Unfortunately, these designs inevitably complicate the manufacturing process and deteriorate the operation robustness of the detector. In this research, a boron-lined honeycomb convertor based neutron detector (BHCND) is proposed to address these problems. A new process, the migration of electrons driven by an electric field from their birth places near the 10B（n，α）7Li reaction points to a outside electron multiplier, is introduced. This design has been confirmed by the pre-research and showed the simplified manufacturing process and a better operation robustness, as well the ~mm scale spatial resolution for the neutron detection. It also has a directional neutron sensitivity and the good capability of suppressing cross-talk neutrons, which can suppress the background neutrons by 10 times and improve the S/B (signal vs background) ratio of the detection system significantly. The principal physical and technique issues will be further studied in this research, in order to develop a new neutron detector that may replace the 3He counter in the area of neutron scattering.