Results from one thousand days of real-time, directional solar-neutrino data

A data sample of 1040 days from the Kamiokande II detector, consisting of subsamples of 450 days at electron-energy threshold E(e) greater than or equal to MeV and 590 days at E(e) greater than or equal to 7.5 MeV, yields a clear directional correlation of the solar-neutrino-induced electron events with respect to the sun and a measurement of the differential electron-energy distribution. These provide unequivocal evidence for the production of B-8 by fusion in the sun. The measured flux of B-8 solar neutrinos from the two subsamples relative to a prediction of the standard solar model is 0.46 + or - 0.05 (stat) + or - 0.06 (syst). The total data sample is tested for short term time variation and, within the statistical error no significant variation is observed. (Author)