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

Searches for possible day-night and semiannual variations of the ⁸B 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 sin²2{θ}>0.02 and 2×{}10^-6{}{Δ}m²{}10^-5 eV² is excluded at 90% C.L. without any assumption on the absolute value of the expected solar neutrino flux.