Solar neutrinos: Near-far asymmetry and just-so oscillations

Abstract

We propose to study possible signals of just-so oscillations in new-generation solar neutrino experiments by separating the events detected when the earth is nearest to the sun (perihelion $\pm$~3~months) from those detected when the earth is farthest from the sun (aphelion $\pm$~3~months). We introduce a solar model independent near-far asymmetry, which is non-zero if just-so oscillations occur. We apply our calculations to the kinetic energy spectra of electrons induced by $^8$B solar neutrino interactions in the SuperKamiokande and Sudbury Neutrino Observatory experiments. We show that the sensitivity to the neutrino oscillation parameters can be increased by probing the near-far asymmetry in selected parts of the electron energy spectra.