Solar 8B and hep Neutrino Measurements from 1258 Days of Super-Kamiokande Data

TL;DR

This paper reports on solar neutrino measurements from Super-Kamiokande over 1258 days, including flux, asymmetry, spectral analysis, seasonal variation, and hep neutrino flux limits, providing insights into solar neutrino properties and oscillations.

Contribution

First detailed measurement of solar neutrino flux and spectral features from Super-Kamiokande with extended data set and analysis of seasonal and day-night variations.

Findings

Measured solar neutrino flux at 45% of BP2000 SSM prediction.

Found no significant spectral distortion or day-night asymmetry.

Set an upper limit on hep neutrino flux at 4.3 times the SSM prediction.

Abstract

Solar neutrino measurements from 1258 days of data from the Super-Kamiokande detector are presented. The measurements are based on recoil electrons in the energy range 5.0-20.0MeV. The measured solar neutrino flux is 2.32 +- 0.03(stat.) +0.08-0.07(sys.)*10^6cm^{-2}s^{-1}, which is 45.1+-0.5(stat.)+1.6-1.4(sys.)% of that predicted by the BP2000 SSM. The day vs night flux asymmetry is 0.033+-0.022(stat.)+0.013-0.012(sys.). The recoil electron energy spectrum is consistent with no spectral distortion (\chi^2/d.o.f. = 19.0/18). The seasonal variation of the flux is consistent with that expected from the eccentricity of the Earth's orbit (\chi^2/d.o.f. = 3.7/7). For the hep neutrino flux, we set a 90% C.L. upper limit of 40 *10^3cm^{-2}s^{-1}, which is 4.3 times the BP2000 SSM prediction.