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HK: Fachverband Physik der Hadronen und Kerne

HK 6: Instrumentation I

HK 6.8: Vortrag

Montag, 27. März 2017, 18:30–18:45, F 072

Aging of recent lifetime enhanced Microchannel-Plate Photomultipliers — •Markus Pfaffinger, Merlin Böhm, Rafael Frytz, Albert Lehmann, Daniel Miehling, Samuel Stelter, and Fred Uhlig for the PANDA collaboration — Physikalisches Institut , Universität Erlangen-Nürnberg

At the PANDA experiment at the new FAIR facility two DIRC detectors will be used for particle identification. The focal plane of the detectors will be located inside a magnetic field of >1 Tesla. Microchannel-Plate Photomultipliers (MCP-PMTs) are the favored sensors for the detection of the Cherenkov photons. As the lifetime is a known caveat this has has to be carefully tested and optimized. The quantum efficiency (QE) is an indicator of the MCP-PMT lifetime. The QE may decrease because of aging processes taking place at the photo cathode (PC) till the sensor is "blind". The aging process is mainly caused by feedback ions from the residual gas in the MCP-PMT, which may damage the PC on impact. The QE degradation is correlated to the integrated anode charge (IAC) having been measured in the sensor. With the Erlangen lifetime setup new MCP-PMTs are being illuminated and their IAC is monitored. In time intervals of a few weeks the spectral QE is measured and full surface QE scans are made every few months. This talk will present the current status of the measurement systems and the latest results, especially of the most recent 2 inch MCP-PMTs from Hamamatsu and Photonis. IACs of >>5 C/cm² were obtained with no or only minor declines of the QE. This is sufficient for the PANDA DIRCs. - Funded by BMBF and GSI -