紫外单光子成像系统增益特性研究

介绍了基于微通道板和楔条形阳极的紫外单光子成像系统的组成和工作原理.利用该系统分别研究了两块和三块微通道板在不同电压下的暗计数特性.实验和拟合结果表明微通道板的暗计数脉冲幅度呈负指数型分布，暗计数率随电压升高而增大.通过测试不同电压下的脉冲幅度分布曲线，发现微通道板增益在较高电压下更加均匀.研究了两块微通道板情况下，微通道板电压和间距对系统分辨率的影响.结果表明，系统分辨率随微通道板电压增加而提高；另外，适当增加微通道板间距也可以提高系统分辨率. 关键词： 单光子计数成像 微通道板 楔条形阳极 分辨率

Gain characteristic of ultraviolet single photon imaging system

Single-photon-counting imaging technology has been widely used in ultraweak bioluminescence, space environment detection and nuclear radiation detection. The structure and working principle of an ultraviolet single photon imaging system based on the microchannel plates and the wedge and strip anode are introduced. The gain characteristic of dark count of two and three microchannel plates is investigated under different voltages respectively. The experimental and fitted results show that the dark count pulse height distribution of microchannel plate has exponential distribution, and the dark count rate rises as the voltage increases. It is shown that the gain becomes more homogeneous as the voltage increases by measuring the pulse height distribution under different voltages. Then the effects of microchannel plate voltage and distance on system resolution with two microchannel plates are tested. It is revealed that the system resolution rises as the voltage of microchannel plate increases, and can be improved also by increasing the distance of microchannel plate properly.