Y. Fukuda et al., Constraints on neutrino oscillation parameters from the measurement of day-night solar neutrino fluxes at Super-Kamiokande, PHYS REV L, 82(9), 1999, pp. 1810-1814
A search for day-night variations in the solar neutrino flux resulting from
neutrino oscillations has been carried out using the 504 day sample of sol
ar neutrino data obtained at Super-Kamiokande, The absence of a significant
day-night variation has set an absolute: Bur independent exclusion region
in the two neutrino oscillation parameter space. [S0031-9007(99)08599-3].