Search

With SNO data [SNO Collaboration, nucl-ex/0106015] on electron–neutrino flux from the sun, it is possible to derive the νesurvival probability Pee(E) from existing experimental data of Super-Kamiokande, gallium experiments and Homestake. The combined data of SNO and Super-Kamiokande provide boron νeflux and the total flux of all active boron neutrinos, giving thus Pee(E) for boron neutrinos. The Homestake detector, after subtraction of the signal from boron neutrinos, gives the flux of Be+CNO neutrinos, and Peefor the corresponding energy interval, if the produced flux is taken from the Standard Solar Model (SSM). Gallium detectors, GALLEX, SAGE and GNO, detect additionally pp-neutrinos. The ppflux can be calculated subtracting from the gallium signal the rate due to boron, beryllium and CNO neutrinos. The ratio of the measured pp-neutrino flux to that predicted by the SSM gives the survival probability for pp-neutrinos. Comparison with theoretical survival probabilities shows that the best (among known models) fit is given by LMA and LOW solutions.

Experimental determinations of the pp and pep fluxes have great potentialities. We briefly review the reasons that make such measurements privileged tests of neutrino properties. We discuss the predictions for these fluxes given by four goodsolutions to the solar neutrino problem: small- and large-angle MSW and Just-So oscillations into active neutrinos, and small-angle MSW oscillations into sterile neutrinos. In addition, we examine the impact of the planned Hellaz detector, which should measure separately the νeand νμfluxes in the pp energy window and the signal from the pep neutrinos, for distinguishing among the different solutions and for determining the solar central temperature.