Detection of nuclear de-excitation gamma-rays in water Cherenkov detector

We measured de-excitation gamma-rays from 15N*s-hole state via the 16O(p,2p)15N. The emission probabilities for more than 6 MeV and 3-6 MeV gamma-rays are estimated to be 3% and 5% respectively. This result is useful for tagging nucleon decay via p→ν¯K+ in Super-Kamiokande and neutrino neutral current interaction study.