Search for day-night and semiannual variations in the solar neutrino flux observed in the Kamiokande-II detector

Abstract

Searches for possible day-night and semiannual variations of the $^{8}\mathrm{B}$ solar neutrino flux are reported based on 1040 days of Kamiokande-II data. Within statistical error, no such short-time variations were observed. The limit on the day-night difference sets a constraint on neutrino-oscillation parameters. A region defined by ${\mathrm{sin}}^{2}$2\ensuremath{\theta}>0.02 and 2\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}6}$\ensuremath{\lesssim}\ensuremath{\Delta}${\mathit{m}}^{2}$\ensuremath{\lesssim}${10}^{\mathrm{\ensuremath{-}}5}$ ${\mathrm{eV}}^{2}$ is excluded at 90% C.L. without any assumption on the absolute value of the expected solar neutrino flux.