Real Time, Directional Measurement of BORON-8 Solar Neutrinos in the Kamiokande-II Detector and Search for Short-Time Variation
Neutrinos from the decay of ^8 B in the Sun have been observed in the Kamiokande -II detector. Based on 802 live detector days in the time period January 1987 through July 1989, the measured flux for Ee >=q 9.5 MeV is 0.39 +/- 0.09 (stat.) +/- 0.07 (syst.) of the value predicted by the standard solar model. The Kamiokande-II result confirms the accuracy of the 37 Cl radiochemical experiment, and also the existence of the so-called solar neutrino problem. The data suggest with low statistical significance a decrease in the observed ^8B solar neutrino flux during a 2.5 year interval in which the sunspot rate increased by approximately an order of magnitude. Within experimental errors, no evidence for either a day-night effect or a seasonal variation was found in the present data.
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- Physics: Elementary Particles and High Energy, Physics: Astronomy and Astrophysics