Measurement system of light curves from nearby supernova bursts for the Super-Kamiokande experiment

Super-Kamiokande is a ring imaging Cherenkov detector for astro-particle physics that consists of 50 ktons pure water and about 13000 photomultiplier tubes (PMT). As well as measuring atmospheric and solar neutrinos, one of the main purposes of the detector is to detect neutrinos from a supernova burst. In the case of a nearby supernova burst which occurs at a distance of 500 light years, the neutrino event rate in the Super-Kamiokande detector is expected to reach 30 MHz and it becomes a huge load for the current data acquisition (DAQ) system. Therefore we are developing an independent DAQ system as a backup for such a nearby supernova burst. This system will measure and record total number of hits in the detector using the digitized signals from the current front-end electronics, from which we can obtain a time variation of total charge deposited in the detector during the supernova burst period. The specification of the new system and current status of the development will be reported.