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 subsampks of 450 days at electron-energy threshold E _e ≥ 9.3 MeV and 590 days at E _e ≥ 7.5 MeV, yields a dear 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 ⁸B by fusion in the Sun. The measured flux of ⁸B solar neutrinos from the two subsampks relative to a prediction of the standard solar model is 0.46 ± 0.05(stat) ± 0.06(syst). The tout data sample is tested for short-term time variation; within the statistical error, no significant variation is observed.