PA-PRO-2017-015

The favored photon sensors for the DIRC (detection of internally reflected Cherenkov light) detectors at the PANDA (Anti-proton Annihilation at Darmstadt) experiment at FAIR (Facility for anti-proton and ion research) are microchannel-plate photomultipliers (MCP-PMTs). The main problem until a few years ago was the limited lifetime of the MCP-PMTs caused by a rapid decrease in quantum efficiency (QE) of the photo cathode (PC) with increasing integrated anode charge (IAC). These limitations are overcome by applying an atomic layer deposition (ALD) coating on the MCPs, as recently done by PHOTONIS and Hamamatsu. During the last years tests of lifetime enhanced MCP-PMTs were performed and their results were compared. For this the QE was measured in dependence of the IAC as function of the wavelength and position dependent across the PC. The best performing tubes show a lifetime increase compared to not enhanced devices by a factor > 50 with an IAC > 13 C/cm2. Additionally, performance results of new 2 inch Hamamatsu tubes and a new high QE PHOTONIS tube are presented.