Solar Neutrino Results from Super-Kamiokande

Understand

Super-Kamiokande-IV (SK-IV) data taking began in September of 2008, after upgrading the electronics and data acquisition system.

• Due to these upgrades and improvements to water system dynamics, calibration and analysis techniques, a solar neutrino signal could be extracted at recoil electron kinetic energies as low as 3.5 MeV.
• When the SK-IV data is combined with the previous three SK phases, the SK extracted solar neutrino flux is found to be $[2.37\pm0.015\mbox{(stat.)}\pm0.04\mbox{(syst.)}]\times10^6$/(cm$^{2}$sec).
• The combination of the SK recoil electron energy spectra slightly favors distortions due to a changing electron flavor content.