Solar neutrino experiments: recent results and future prospects

Abstract

Recent results from the SNO and Borexino solar neutrino experiments have pushed the observation of solar neutrinos to lower energies. Borexino's measurement of the rate of 7Be solar neutrinos demonstrates that the survival probability for solar neutrinos below 1 MeV is larger than for the 8B solar neutrinos, consistent with our expectation for neutrino propagation affected by matter. On the other hand, by looking at lower energy 8B solar neutrinos, SNO (and also Borexino) do not see the predicted rise in the survival probability and there is even a hint that the survival probability drops to a lower value. Future solar neutrino experiments, in particular the SNO+ experiment, will look at this question by making precision measurements of the survival probability of the pep solar neutrinos (1.44 MeV energy).