采用金阴极的光子计数成像探测器的性能

Properties of Photon Counting Imaging Detector with Au Photocathode

采用Au作为感应读出式光子计数成像探测器的光阴极,在分辨率测试板上蒸镀了薄膜厚度为15nm的Au作为透射式阴极。实验测试了加Au阴极后微通道板(MCP)的增益性能,探测器的分辨率和计数率等成像性能,与未加Au阴极时相应的系统性能做了对比。结果表明,加Au阴极后MCP的脉冲高度分布呈准高斯型,随着MCP工作电压的提高,脉冲高度分布曲线的峰值向高增益方向移动,曲线的半峰全宽(FWHM)逐渐变宽;Au阴极有效提高了光子计数成像探测器的探测效率和信噪比;分辨率测试结果表明加Au阴极后探测器的空间分辨率优于75μm,随着计数率的提高分辨率将会下降,在保证系统分辨率优于150μm时计数率可达到13.5kHz。

Au photocathode is used in photon counting imaging system with induction readout.A 15 nm gold film is deposited on the resolution test board and it is used for transmission photocathode.The gain performance of micro-channel plates（MCP）,resolution and counting rate of the detector with Au photocathode are tested.The results show that the system with Au cathode has a quasi-Gaussian pulse height distribution（PHD） curves.The peak of the PHD curves moved to the high-gain zone and the full width at half maximum（FWHM） gradually widened as the voltage increased.After the adoption of Au cathode,the detection efficiency and the signal-to-noise ratio of photon counting imaging detector effectively improved.The resolution test results show that the spatial resolution of the detector is better than 75 μm,and the counting rate can reach 13.5 kHz when the system′s resolution is better than 150 μm.