Significantly improved lifetime of micro-channel plate PMTs

The lifetime of the most recent generation micro-channel plate (MCP) PMTs of BINP, Hamamatsu (R10754X) and PHOTONIS (XP85112) is being studied in a simultaneous measurement. We find that the new techniques applied to reduce the aging of the photocathode of the MCP-PMTs has significantly increased the lifetime. Dark count rate, gain and quantum efficiency of the tubes are given as a function of the integrated anode charge. Several times the quantum efficiency was also measured across the surface of the photocathode. At this point of the ongoing measurements the best MCP-PMT turns out to be the XP85112 with its MCP surfaces coated by an atomic layer to reduce the outgassing of the lead glass. This tube shows no aging after an integrated anode charge of 2.1 C/cm2 which is more than an order of magnitude better than that of previous generation MCP-PMTs.