Stefan Schoenert

Title

Solar Neutrino Spectroscopy with BOREXINO at Gran Sasso

Abstract

The physics program of the Borexino experiment at the Gran Sasso underground laboratory focuses on the measurement of low-energy solar neutrinos. Data taking started in May 2007. With the achieved unprecedented radio-purity of the detector materials, the Borexino collaboration succeeded after only two months of data taking to measure neutrinos in real time which are emitted in the electron capture of 7Be in the core of the Sun. Now, after about one year of continuous operations, the accuracy of the measured interaction rate of the 0.862 MeV 7Be neutrinos could be improved to 49± 3(stat)± 4(syst) counts/(day ·100 tons). Very recently, the 8B neutrino flux could be studied down to 2.8 MeV, the lowest threshold achieved so far. The 7Be and low-energy 8B neutrino flux measurements probe for the first time directly the survival probability for solar neutrinos in the transition region between matter-enhanced and vacuum driven neutrino oscillations. Future prospectives for the studies of pep- and CNO neutrinos, as well as anti-neutrinos from the interior of the earth will be presented.