Measurement of the Total Active B 8 Solar Neutrino Flux at the Sudbury Neutrino Observatory with Enhanced Neutral Current Sensitivity

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…