Count Rate Performance of a Microchannel Plate Photomultiplier

The count rate dependent gain change of a microchannel plate photomultiplier has been measured. Gain changes of 60% have been observed for count rates in excess of 2 × 105 s-1. The microchannel plate photomultiplier was used as a multiplying element of a scintillation detector system using NaI(Tl) as the scintillator. Data are compared to a simplified model of this form of photomultiplier.