Measurement of the Rate ofνe+d→p+p+e−Interactions Produced byB8Solar Neutrinos at the Sudbury Neutrino Observatory

Abstract

Solar neutrinos from ${}^8\mathrm{B}$ decay have been detected at the Sudbury Neutrino Observatory via the charged current (CC) reaction on deuterium and the elastic scattering (ES) of electrons. The flux of ${\nu }_e$’s is measured by the CC reaction rate to be ${\phi }^{\mathrm{CC}}\left({\nu }_e\right)=1.75\mathrm{}\pm 0.07\left(\mathrm{stat}{)}_{-0.11\mathrm{}}^{+0.12\mathrm{}}\right(\mathrm{syst})\pm 0.05(\mathrm{theor})\times {10}^6{\mathrm{cm}}^{-2\mathrm{}}{\mathrm{s}}^{-1\mathrm{}}$. Comparison of ${\phi }^{\mathrm{CC}}\left({\nu }_e\right)$ to the Super-Kamiokande Collaboration’s precision value of the flux inferred from the ES reaction yields a $3.3\sigma$ difference, assuming the systematic uncertainties are normally distributed, providing evidence of an active non- ${\nu }_e$ component in the solar flux. The total flux of active ${}^8\mathrm{B}$ neutrinos is determined to be $5.44\pm 0.99\times {10}^6{\mathrm{cm}}^{-2\mathrm{}}{\mathrm{s}}^{-1\mathrm{}}$.