SolarB8and hep Neutrino Measurements from 1258 Days of Super-Kamiokande Data

Abstract

Solar neutrino measurements from 1258 days of data from the Super-Kamiokande detector are presented. The measurements are based on recoil electrons in the energy range 5.0–20.0 MeV. The measured solar neutrino flux is $2.32\pm 0.03\left(\mathrm{stat}{)}_{-0.07\mathrm{}}^{+0.08\mathrm{}}\right(\mathrm{syst})\times {10}^6{\mathrm{cm}}^{-2\mathrm{}}{\mathrm{s}}^{-1\mathrm{}}$, which is $45.1\pm 0.5\left(\mathrm{stat}{)}_{-1.4\mathrm{}}^{+1.6\mathrm{}}\right(\mathrm{syst})\%$ of that predicted by the BP2000 SSM. The day vs night flux asymmetry $({\Phi }_n-{\Phi }_d)/{\Phi }_{\mathrm{average}}$ is $0.033\pm 0.022\left(\mathrm{stat}{)}_{-0.012\mathrm{}}^{+0.013\mathrm{}}\right(\mathrm{syst})$. The recoil electron energy spectrum is consistent with no spectral distortion. For the hep neutrino flux, we set a $90\%$ C.L. upper limit of $40\times {10}^3{\mathrm{cm}}^{-2\mathrm{}}{\mathrm{s}}^{-1\mathrm{}}$, which is 4.3 times the BP2000 SSM prediction.