System for photomultiplier tubes characterization and data acquisition for Water Cherenkov Detectors

A water Cherenkov detector uses the emission of Cherenkov radiation for detecting the trace of secondary particles generated by extensive air shower cascades traversing a purified water tank. These are used for the detection of high energy gamma-rays. A fundamental component of the detectors consists of the photomultiplier tubes (PMTs) used for detection of the Cherenkov radiation that is produced by very high energy particles moving faster than the speed of of light in the medium. INAOE, being one of the leading institutions of HAWC, decided to develop a system to characterize the PMTs that includes measurement of dark current, linear response region determination, response to a photoelectron and hence the gain. This characterization is indispensable when several PMTs operate in an array of water Cherenkov detectors. The system was further developed to simultaneously acquire data of several phototubes, allowing also to measure coincidences. Additionally, the VME scalers modules will be used to monitor up to 32 phototubes. This system has been used to characterize the PMTs of the LAGO experiment and can be used in the future for any type of PMT system.