UC Berkeley

The SNO+$$+$$ collaboration reports its first spectral analysis of long-baseline reactor antineutrino oscillation using 114 tonne-years of data. Fitting the neutrino oscillation probability to the observed energy spectrum yields constraints on the neutrino mass-squared difference Δm212$$\Delta m^2_{21}$$. In the ranges allowed by previous measurements, the best-fit Δm212$$\Delta m^2_{21}$$ is (8.85-1.33+1.10$$8.85^{+1.10}_{-1.33}$$) ×$$\times $$10-5$$10^{-5}$$eV2$$\hbox {eV}^2$$. This measurement is continuing in the next phases of SNO+ and is expected to surpass the present global precision on Δm212$$\Delta m^2_{21}$$ with about three years of data.