Combined Analysis of all Three Phases of Solar Neutrino Data from the Sudbury Neutrino Observatory

TL;DR

This paper presents a comprehensive analysis of all phases of solar neutrino data from the Sudbury Neutrino Observatory, refining neutrino flux measurements and oscillation parameters through improved background rejection and combined data analysis.

Contribution

It provides the first combined analysis of all SNO phases with enhanced background rejection, leading to more precise neutrino flux and oscillation parameter measurements.

Findings

Measured total active neutrino flux from 8B decays: (5.25 ± 0.16(stat.)+0.11-0.13(syst.))×10^6 cm^{-2}s^{-1}

Determined neutrino oscillation parameters: Δm^2_{21} ≈ 5.6×10^{-5} eV^2, tan^2θ_{12} ≈ 0.427

Set an upper bound on θ_{13}: sin^2θ_{13} < 0.053 at 95% C.L.

Abstract

We report results from a combined analysis of solar neutrino data from all phases of the Sudbury Neutrino Observatory. By exploiting particle identification information obtained from the proportional counters installed during the third phase, this analysis improved background rejection in that phase of the experiment. The combined analysis resulted in a total flux of active neutrino flavors from 8B decays in the Sun of (5.25 \pm 0.16(stat.)+0.11-0.13(syst.))\times10^6 cm^{-2}s^{-1}. A two-flavor neutrino oscillation analysis yielded \Deltam^2_{21} = (5.6^{+1.9}_{-1.4})\times10^{-5} eV^2 and tan^2{\theta}_{12}= 0.427^{+0.033}_{-0.029}. A three-flavor neutrino oscillation analysis combining this result with results of all other solar neutrino experiments and the KamLAND experiment yielded \Deltam^2_{21} = (7.41^{+0.21}_{-0.19})\times10^{-5} eV^2, tan^2{\theta}_{12} = 0.446^{+0.030}_{-0.029}, and sin^2{\theta}_{13} = (2.5^{+1.8}_{-1.5})\times10^{-2}. This implied an upper bound of sin^2{\theta}_{13} < 0.053 at the 95% confidence level (C.L.).