Neutron tagging and its physics application in Super-Kamiokande-IV

摘要

With the electronics upgrade in 2008, the fourth phase of Super-Kamiokande (SK) is now capable of detectingthermal neutrons from neutrino interactions with 20% efficiency. Observation of neutrons produced in atmosphericneutrino interactions is presented. Preliminary results of a background study for the supernova relic neutrino (SRN)detection are shown. Prospects of future SRN searches and possible improvement of background rejection for protondecay searches with neutron tagging in SK-IV and beyond are also discussed.