Measurements of the Solar Neutrino Flux from Super-Kamiokande's First 300 Days

TLDR

Data from 31 May 1996 to 23 June 1997 were used to obtain the results. The first Super‑K solar neutrino flux measurement, using recoil electrons above 6.5 MeV, yields a total ${}^{8}$B flux of $2.42^{+0.10}_{-0.07}\pm0.06\times10^6$ cm$^{-2}$ s$^{-1}$, consistent with Kamiokande and 36 % of the BP95 model, and shows no time variation over 1.5‑month intervals.

Abstract

The first results of the solar neutrino flux measurement from Super-Kamiokande are presented. The results shown here are obtained from data taken between 31 May 1996, and 23 June 1997. Using our measurement of recoil electrons with energies above 6.5 MeV, we infer the total flux of ${}^{8}\mathrm{B}$ solar neutrinos to be $2.42\ifmmode\pm\else\textpm\fi{}0.06(\mathrm{stat}{)}_{\ensuremath{-}0.07}^{+0.10}(\mathrm{syst})\ifmmode\times\else\texttimes\fi{}{10}^{6}\mathrm{cm}{}^{\ensuremath{-}2}{\mathrm{s}}^{\ensuremath{-}1}$. This result is consistent with the Kamiokande measurement and is 36% of the flux predicted by the BP95 solar model. The flux is also measured in 1.5 month subsets and shown to be consistent with a constant rate.