A system for the characterization of the HAWC PMTs sensitivity

摘要

The HAWC Project is a very high-energy gamma-ray observatory under construction at the Sierra Negra volcano (4100meters above sea level) in the Pico de Orizaba National Park located in central Mexico. HAWC will reuse the 900Hamamatsu R5912 photomultipliers (PMTs) from Milagro Observatory for the 300 Water Cherenkov Detectors. In orderto characterize their present performance it is necessary to scan the active area of the photocathode by measuring itsefficiency and gain. A characterization system was designed and manufactured to achieve an automated measurement ofover 100 points distributed on the PMT active spherical surface. Preliminary results show the variation of QE of PMTswith respect of the position of incoming photons, as well as the changes in the PMTs response due to the Earth'smagnetic field and gain vs. high voltage. The system allows automated PMT characterization improving its performance,reliability, precision and repeatability. In this work we present the characterization system and preliminary results on thePMT efficiency.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.