Search for Supernova Relic Neutrinos with 2.2 MeV Gamma Tagging at Super-Kamiokande-IV

Tagging the 2.2 MeV gamma released from a neutron capture on hydrogen can provide an effective tool in identifying low-energy electron anti-neutrinos, and can thus reduce the background in supernova relic neutrino searches. With 960 days data at Super-Kamiokande-IV applying this new technique, no significant signals are found in the energy range 13.3 MeV < < 31.3 MeV. A differential flux upper limit is calculated with no model dependence assumed.