Abstract
We report the direct measurement of the solar neutrino signal rate performed with the Borexino detector at the Laboratori Nazionali del Gran Sasso. The interaction rate of the 0.862 MeV neutrinos is . The hypothesis of no oscillation for solar neutrinos is inconsistent with our measurement at the C.L. Our result is the first direct measurement of the survival probability for solar in the transition region between matter-enhanced and vacuum-driven oscillations. The measurement improves the experimental determination of the flux of , , and CNO solar , and the limit on the effective neutrino magnetic moment using solar neutrinos.
- Received 9 June 2008
DOI:https://doi.org/10.1103/PhysRevLett.101.091302
©2008 American Physical Society