Recent measurements on the Hamamatsu 13 in., R8055, PhotoMultiplier Tubes

Abstract The key component of NESTOR, the deep-sea Cherenkov neutrino telescope, built in the Mediterranean, NW of Greece, is the optical module. The NESTOR Optical Module employs a PhotoMultiplier Tube (PMT) in a transparent glass pressure housing. The Hamamatsu PMT R8055-01, 13 in. photomultiplier was selected for NESTOR to replace the old 15′′ Hamamatsu PMTs (R2018-03). Extensive tests have been made on the sensitivity, uniformity, time resolution and noise rates of 162 R8055-01 13 in. PMTs