Measurement of the Total ActiveB8Solar Neutrino Flux at the Sudbury Neutrino Observatory with Enhanced Neutral Current Sensitivity

The Sudbury Neutrino Observatory has precisely determined the total active (νₓ) ⁸B solar neutrino flux without assumptions about the energy dependence of the νₑ 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 $5.21±{}0.27(stat)±{}0.38(syst)×{}{10}⁶ {cm}^{{-}2} {s}^{{-}1}$, in agreement with previous measurements and standard solar models. A global analysis of these and other solar and reactor neutrino results yields ${Δ}{m}²={7.1}_{{-}0.6}+1.2×{}{10}^{{-}5} {eV}²$ and ${θ}={32.5}_{{-}2.3}+2.4$ degrees. Maximal mixing is rejected at the equivalent of 5.4 standard deviations.