Measurement of reactor antineutrino oscillation at SNO+

TL;DR

The SNO+ collaboration's spectral analysis of reactor antineutrinos provides a highly precise measurement of neutrino oscillation parameters and reports the first geoneutrino flux measurement in the Western Hemisphere.

Contribution

This work presents the second spectral analysis with 286 tonne-years of data, achieving the most precise determination of Δm²₁₂ and a first measurement of geoneutrino flux at SNO+.

Findings

Precise measurement of Δm²₁₂ = (7.96^{+0.48}_{-0.42}) × 10^{-5} eV².

Combined analysis yields Δm²₁₂ = (7.58^{+0.18}_{-0.17}) × 10^{-5} eV² and sin²θ₁₂ = 0.308 ± 0.013.

First measurement of geoneutrino flux in the Western Hemisphere: 73^{+47}_{-43} TNU.

Abstract

The SNO+ collaboration reports its second spectral analysis of reactor antineutrino oscillation using 286 tonne-years of new data. The measured energies of reactor antineutrino candidates were fitted to obtain the second-most precise determination of the neutrino mass-squared difference $\Delta m^2_{21}$ = ($7.96^{+0.48}_{-0.42}$) $\times$ 10$^{-5}$ eV$^2$. Constraining $\Delta m^2_{21}$ and $\sin^2\theta_{12}$ with measurements from long-baseline reactor antineutrino and solar neutrino experiments yields $\Delta m^2_{21}$ = ($7.58^{+0.18}_{-0.17}$) $\times$ 10$^{-5}$ eV$^2$ and $\sin^2\theta_{12} = 0.308 \pm 0.013$. This fit also yields a first measurement of the flux of geoneutrinos in the Western Hemisphere, with $73^{+47}_{-43}$ TNU at SNO+.