Precision measurement of solar neutrino oscillation parameters by a long-baseline reactor neutrino experiment in Europe

Abstract

We consider the determination of the solar neutrino oscillation parameters $Δm^2_{21}$ and $θ_{12}$ by studying oscillations of reactor anti-neutrinos emitted by nuclear power plants (located mainly in France) with a detector installed in the Frejus underground laboratory. The performances of a water Cerenkov detector of 147 kt fiducial mass doped with 0.1% of Gadolinium (MEMPHYS-Gd) and of a 50 kt scale liquid scintillator detector (LENA) are compared. In both cases 3$σ$ uncertainties below 3% on $Δm^2_{21}$ and of about 20% on $\sin^2θ_{12}$ can be obtained after one year of data taking. The Gadolinium doped Super-Kamiokande detector (SK-Gd) in Japan can reach a similar precision if the SK/MEMPHYS fiducial mass ratio of 1 to 7 is compensated by a longer SK-Gd data taking time. Several years of reactor neutrino data collected by MEMPHYS-Gd or LENA would allow a determination of $Δm^2_{21}$ and $\sin^2θ_{12}$ with uncertainties of approximately 1% and 10% at 3$σ$, respectively. These accuracies are comparable to those that can be reached in the measurement of the atmospheric neutrino oscillation parameters $Δm^2_{31}$ and $\sin^2θ_{23}$ in long-baseline superbeam experiments.