Measurement of the Total Active<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">B</mml:mi><mml:mprescripts/><mml:none/><mml:mn>8</mml:mn></mml:mmultiscripts></mml:math>Solar Neutrino Flux at the Sudbury Neutrino Observatory with Enhanced Neutral Current Sensitivity

Abstract

The Sudbury Neutrino Observatory has precisely determined the total active (${\ensuremath{\nu}}_{x}$) $^{8}\mathrm{B}$ solar neutrino flux without assumptions about the energy dependence of the ${\ensuremath{\nu}}_{e}$ survival probability. The measurements were made with dissolved NaCl in heavy water to enhance the sensitivity and signature for neutral-current interactions. The flux is found to be $5.21\ifmmode\pm\else\textpm\fi{}0.27\mathrm{(}\mathrm{stat}\mathrm{)}\ifmmode\pm\else\textpm\fi{}0.38\mathrm{(}\mathrm{syst}\mathrm{)}\ifmmode\times\else\texttimes\fi{}{10}^{6}\text{ }{\mathrm{cm}}^{\ensuremath{-}2}\text{ }\text{ }{\mathrm{s}}^{\ensuremath{-}1}$, in agreement with previous measurements and standard solar models. A global analysis of these and other solar and reactor neutrino results yields $\ensuremath{\Delta}{m}^{2}={7.1}_{\ensuremath{-}0.6}^{+1.2}\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}\text{ }{\mathrm{eV}}^{2}$ and $\ensuremath{\theta}={32.5}_{\ensuremath{-}2.3}^{+2.4}$ degrees. Maximal mixing is rejected at the equivalent of 5.4 standard deviations.