ABSTRACT
We discuss the results of Homestake and Kamioka experiments, showing that – if the results of these experiments are taken at their face values – one way to save “conventional neutrinos” is to look for a nuclear solution decreasing both 7Be and 8B neutrino fluxes with respect to the predictions of the standard solar models. Recent GALLEX results appear in agreement with such a conclusion. We discuss the sensitivity of the 8B and 7Be neutrino fluxes to the behaviour of the low energy 3He + 3He and 3He+4He cross sections. We derive analytically the dependence of the neutrino fluxes on the low energy nuclear cross sections. This analytical approach has been supported by numerical experiments based on a new Standard Solar Model. In the non-resonant case, reduction of the neutrino fluxes to about 1/3 of the Standard Solar Model could be obtained if the true value of 534(0) is three times smaller than the presently accepted extrapolated value. Alternatively, one should have S33(0) wrong by a factor nine. A resonance in the 3He + 3He channel could yield a sufficient reduction of 8B neutrinos and, furthermore, a suppression of 7Be neutrinos larger than that of8B neutrinos provided that E R≤21.4 keV, an energy region so far almost unexplored experimentally. We show that future experiments in underground laboratories should be able to explore the region down to E R = 10 keV with a significant sensitivity. We also compare our Standard Solar Model with the results of previous calculations.
