New Results On Solar Neutrino Fluxes From 192 Days Of Borexino Data

We report the direct measurement of the Be-7 solar neutrino signal rate performed with the Borexino detector at the Laboratori Nazionali del Gran Sasso. The interaction rate of the 0.862 MeV Be-7 neutrinos is 49 +/- 3(stat)+/-(syst) counts/(day.100 ton). The hypothesis of no oscillation for 7Be solar neutrinos is inconsistent with our measurement at the 4 sigma C.L. Our result is the first direct measurement of the survival probability for solar nu(e) in the transition region between matter-enhanced and vacuum-driven oscillations. The measurement improves the experimental determination of the flux of Be-7, pp, and CNO solar nu(e), and the limit on the effective neutrino magnetic moment using solar neutrinos.