Abstract

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 ${E}_{e}$\ensuremath{\ge}9.3 MeV is 0.46\ifmmode\pm\else\textpm\fi{}0.13(stat)\ifmmode\pm\else\textpm\fi{}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.