Optimizing the design of ultrafast photomultiplier tubes.

Ultrafast microchannel plate (MCP) photomultiplier tubes are under active development. To obtain high gain, high spatial resolution, and good time performance, we comprehensively investigate the effects of the gap distances and voltages from cathode to MCPin and MCPout to anode in a systematic study using the finite integral technique and Monte Carlo method. A three-dimensional model is introduced to simplify the calculations. From the simulation results, a short gap distance and high gap voltage were determined to achieve good time performance, high spatial resolution, and high gain.