Direct probes of neutrino properties using solar-neutrino lines

The spectrum of neutrinos from the Sun contains large fluxes of monoenergetic neutrinos which could be observed in the next generation of solar-neutrino detectors. Such observations directly probe neutrino parameters independent of uncertainties in the standard solar model. Small neutrino mass differences, 10^-11<m₂²-m₁²<10^-8 eV², would cause the measured flux of ⁷line neutrinos to oscillate with a period in the range of a week up to a year. A neutrino magnetic moment comparable to the present laboratory bound would produce large distortions in the spectrum of scattered electrons.