New Results from the Borexino Solar Neutrino Experiment

New Results from the Borexino Solar Neutrino Experiment
Laura Cadonati, UMass Amherst
Date and time: Fri, Oct 14, 2011 - 2:00pm
Location: LGRT 1033
Category: ACFI Seminar
Special notes: See a local news release
Borexino is an ultra-low background experiment for the spectroscopy of low-energy neutrinos. Its primary physics goal is the real time detection of solar neutrinos with energies below 2 MeV, using 300 tons of liquid scintillator in an un-segmented detector at the underground Gran Sasso Laboratory, in Italy. In this talk I will report on three sets of results recently released by the Borexino Collaboration from the analysis of data collected since 2007. First, I will present the measurement of the flux of neutrinos produced in the 7Be electron capture reaction in the Sun. This measurement benefits from an intense calibration campaign for the control of the systematics, and uses a larger data set than previously released results, yielding a total uncertainty of about 5%. Next I will discuss the measurement of day/night asymmetry in 7Be neutrino data and the impact of these results for the validation of the MSW-LMA oscillation model in vacuum, constraints of uncertainties in the pp flux evaluation, and consequences for the global analysis of solar neutrino experiments. Finally, I will describe the first measurement of solar neutrino flux from the pep reaction and limits on the CNO flux, which, combined with the measurements of 7Be and 8B neutrino fluxes in Borexino, provide a unique spectroscopic analysis of the solar neutrino flux within a single detector.