大面积MCP-PMT的优化设计

大面积微通道板型光电倍增管（MCP-PMT）拥有大光阴极覆盖面积、高量子效率以及良好的增益稳定性等优点，广泛应用于众多高精度探测实验中，具有较好的发展前景。但目前为止，大面积MCP-PMT仍存在倍增系统结构未达到最优化、延迟脉冲较严重等问题亟待解决。本课题针对以上问题拟开展大面积MCP-PMT的优化研究工作：（1）设计双MCP倍增系统，实现增益最优化。包括优化单片MCP的长径比、偏置角等结构参数；双MCP的板间距及板间电压的优化设计。（2）优化研究MCP蒸镀材料的二次电子发射特性，在保证高水平收集效率的前提下，达到削弱延迟脉冲的目的；提出设计合理的内置栅网，包括栅网数量、摆放位置以及偏置电压的设计，使延迟脉冲得到有效抑制；提出设计一款前置打拿极型MCP-PMT，将打拿极作为第一倍增极置于未镀膜双MCP之前，预计其收集效率将接近100%，且几乎无延迟脉冲。

Large area photomultiplier tubes based on microchannel plate（MCP-PMTs）with advantages of large photocathode coverage area, high quantum efficiency and good gain stability are widely applied in basic physics detection experiments. It has a good development foreground. Nevertheless, to date there are still some shortcomings: the non-optimal multiplication system and the severe delay pulse. This project will work on the optimization study of the high performance MCP-PMT. The study includes the following two points: (1) Measures will been taken for the optimizations of the multiplication system, including optimizing the MCP structure parameters such as length-diameter ratio, bias angle and so on, and designing the gap distance and voltage of the V-cascaded MCPs. (2) For the delay pulse suppression, secondary electron yield property of the MCP coated material will be studied and optimized with the collection efficiency upon 95%. Besides, placing electric grids upon the top MCP is proposed in this project. The delay pulse will be suppressed by designing the grid number, the position and the applied voltage. In addition, a novel dynode-MCP-PMT is proposed in this project, in which the dynode is placed in front of the MCPs as the first multiplication stage. CE of it is expected to be 100%, and little delay pulse will be observed.