TA-DPG-2018-014

The PANDA experiment at the new FAIR facility will use two DIRC detectors for hadron identification. The focal plane of both DIRC detectors will be located inside a magnetic field of ∼1 T. In the PANDA environment the only sensor option for the detection of the Cherenkov photons are Microchannel-Plate Photomultipliers (MCP-PMTs). The most limiting parameter until a few years ago was the lifetime of the MCP-PMTs. The quantum efficiency (QE) correlated to the integrated anode charge (IAC) being measured in the sensor is an indicator for the lifetime. The QE will decrease with increasing IAC because of aging processes taking place at the photo cathode (PC) until the sensor is "blind". One of these processes is the interaction of feedback ions from the residual gas which may damage the PC on impact. The Erlangen lifetime setup is capable of illuminating various MCP-PMTs simultaneously and monitoring their IAC. The spectral QE of the sensors is measured every few weeks and full surface scans are made every few months. This talk will present the current setup and the latest obtained results. The focus will be on recent 2-inch MCP-PMTs from Photonis and Hamamatsu. IACs of ≫5 C/cm2 were obtained with no or only minor QE loss which is sufficient for both PANDA DIRCs.