Fourier analysis of real - time , high -

Solar neutrino oscillations with wavelengths comparable to the Earth-Sun distance provide a viable explanations of the long-standing solar neutrino deecit. They imply a time-dependent modulation of the solar neutrino ux due to the eccentricity of the Earth orbit. Motivated by this testable prediction, we propose a Fourier analysis of the signal observable in real-time, solar neutrino experiments. We give the general expressions of the Fourier coeecients and of their correlated uncertainties in the presence of background. The expressions assume a particularly compact form in the case of two-avor neutrino oscillations in vacuum. We discuss the sensitivity to the lowest harmonics of the new-generation, high-statistics experiments SuperKamiokande, Sudbury Neutrino Observatory, and Borexino.