Aging and time resolution measurements for the Hamamatsu R7600 multi-anode photomultiplier tube

The Ring Imaging Cherenkov (RICH) detector at LHCb is now readout by Hybrid Photon Detectors. In view of its upgrade a possible option is the adoption of the flat panel Photon Multipliers Tubes R7600, manufactured by Hamamatsu. This detector has just been fully tested in the single photon condition and in this paper the last measurements are presented. The study of the Transit Time Spread was done using Cherenkov light from a PbF₂ crystal and a ²²Na source. The time difference between signals from individual pixels was estimated by means of an offline analysis algorithm and the TTS is estimated to be about 200 ps RMS. A system to measure the gain decrease of the PMT due to aging was also assembled. In this measurements the light was produced by a commercial blue LED and the system was run for about two months; after 500 hours the conversion gain reduced to about 60%.