Observation ofB8solar neutrinos in the Kamiokande-II detector

Neutrinos from the decay of ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ in the Sun have been observed in the Kamiokande-II detector. Based on 450 days of data in the time period January 1987 through May 1988; the measured flux obtained from data with $E_e$≥9.3 MeV is 0.46±0.13(stat)±0.08(sys) of the value predicted by the standard solar model. Within experimental errors, the Kamiokande-II value is in agreement with the corresponding value obtained in the ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$ radiochemical detector in essentially the same time period.