Latest Results from Super-Kamiokande

Abstract

We present the latest results from Super-Kamiokande (SK) for solar, atmospheric and supernova neutrinos. SK has been operating for about 16 years, accumulating the highest statistics of the neutrino event data. The flux and energy spectrum as well as the day/night flux asymmetry of solar neutrinos have been measured precisely. We find the day/night flux asymmetry with the 2.7σ significance, indicating that the electron neutrino regeneration may occur in the earth. The recent discovery of the finite θ13 value motivates us to explore the determination of the neutrino mass hierarchy, θ23 octant and a CP-violating phase using atmospheric neutrinos. SK also has found the appearance of τ neutrinos with the 3.8σ significance in the atmospheric neutrino data sample. The neutrino oscillation parameters are determined based on the solar and atmospheric neutrino measurements. SK has the highest sensitivity to the supernova relic neutrinos that have been accumulated in the universe as a result of the past supernova explosions. We report the latest result of a search for the supernova relic neutrinos. We also mention about the current R&D status of a Gd-loaded water Cherenkov detector.