Recent progress with microchannel-plate PMTs

Microchannel-plate (MCP) PMTs were identified as the only suitable photon sensors for the two DIRC detectors of the P̄ANDA experiment at FAIR. As the long-standing aging problem of MCP-PMTs was recently overcome by coating the MCP pores with an atomic layer deposition (ALD) technique, further improved 2″ MCP-PMTs were investigated. The best PHOTONIS device has reached a lifetime of >20 C/cm2 integrated anode charge without any sign of aging. Also the newly developed 2″ MCP-PMTs of Hamamatsu are maturing and are usable in high rate environments. The status of our long-term lifetime measurements and the performance parameters of the currently most advanced ALD-coated MCP-PMTs from PHOTONIS and Hamamatsu are presented. In addition, first results obtained with a new quality assurance setup for MCP-PMTs are discussed. This setup consists of a high performance DAQ system to measure the response of ≥64 anode pixels simultaneously. The system allows to study and quantify background parameters like position dependent dark count rates and ion afterpulsing as well as temporal and spacial distributions of recoil electrons and the effects of electronic and charge-sharing crosstalk among the anode pixels.