Solar neutrino measurements in Super-Kamiokande-II

TL;DR

This paper reports on the second phase of solar neutrino measurements by Super-Kamiokande-II, confirming previous results and finding no spectral distortion or correlation with solar activity, with precise flux and day-night difference measurements.

Contribution

It provides the second phase results of Super-Kamiokande solar neutrino measurements, confirming consistency with the first phase and improving measurement precision.

Findings

Measured boron 8 flux: 2.38 x 10^6 cm^-2 sec^-1

No spectral distortion observed

No correlation with solar activity

Abstract

The results of the second phase of the Super-Kamiokande solar neutrino measurement are presented and compared to the first phase. The solar neutrino flux spectrum and time-variation as well as oscillation results are statistically consistent with the first phase and do not show spectral distortion. The time-dependent flux measurement of the combined first and second phases coincides with the full period of solar cycle 23 and shows no correlation with solar activity. The measured boron 8 total flux is 2.38 +/-0.05(stat.) +0.16-0.15(sys.) X 10^6 cm^-2 sec^-1 and the day-night difference is found to be -6.3 +/-4.2(stat.) +/-3.7(sys.) %. There is no evidence of systematic tendencies between the first and second phases.