高探测效率低噪声的大面阵热中子敏感微通道板

High Dectection Efficiency Low Noise Large Format Neutron Sensitive Microchannel Plate

在微通道板玻璃中掺中子灵敏核素,并去除玻璃中的天然放射性同位素成份,可以实现微通道板对热中子的敏感,使探测器具有极低的背景事件率.在微通道板玻璃中掺加3mol%的Gd2O3,同时去除玻璃中的K2O和/或Rb2O,制作成50 mm直径、0.6 mm厚度、10μm孔径的微通道板,实现了对25.3meV热中子33%的探测效率,同时探测器的暗计数率低至0.11events cm-2·s-1.通过计算和分析热中子在微通道板基体中的俘获概率和155,157 Gd(n,γ)156,158 Gd反应所能引发的有效信号,说明了通过微通道板的结构优化,掺3mol%Gd2O3的微通道板可以实现最大50%的热中子探测效率.在此基础上,进一步完成了106mm直径10μm孔径的掺3mol%Gd2O3的优化结构大面阵低噪声中子敏感微通道板的制作.

Both direct addition of neutron-absorbing atoms into Microchannel Hate （MCP） glass and elimination of content contained natural radioactive isotope can make MCP sensitive to neutrons without changing the remainder of the fabrication process, while such a neutron-sensitive detector has very low background rate. The 50 mm format and 10 ;m pore size MCP which fabricated by a MCP glass doped with 3 mol; Gd2O3 and eliminate K2O and Rb2O contnent demonstrated its capability to image thermal neutrons with 33% detection efficiency and low dark count rate of 0. 11 events cm^-2 ; s^-1. Through calculation and analysis of the capture probability of neutron within a MCP matrix and the effective signal which arised from 155,157Gd（n,γ）156,158Gd reaction production, our study indicated that the maximum detection efficiency of 50% can be achieved for this MCP doped with 3 mol% Gd2O3 and optimized geometry. In addition, a 106 mm-diameter and 10 ;m pore size neutron sensitive MCP doped with 3 mol; Gd2 O3 and optimized geometry were fabricated based on above-mentioned method.