Solar neutrino measurement in SK and larger detector

The results of solar neutrino data from the first phase of Super-Kamiokande (SK-I) are presented. Super-Kamiokande can measure not only the solar neutrino flux but also its energy spectrum and time variations such as day-night and seasonal differences. The detail oscillation analysis using those information is appeared. Combining all the solar and KamLAND reactor data, the obtained oscillation parameters are determined as Δm2=8.3×10−5eV2 and tan2θ=0.38. The recent results in the second phase of SK (SK-II) are also presented, and its flux, spectrum and time variation are consistent with SK-I. The possibility of future water cherenkov detectors, such as SK-III and Mega-ton class detector, are described. If the current neutrino oscillation parameter is assumed, its spectrum has deficit in the lower energy region. And the possibility of the day-night asymmetry is also discussed.