11C analysis and muon tracking in Borexino for solar pep and CNO neutrino spectroscopy

Borexino is an experiment for low-energy neutrino spectroscopy at the Gran Sasso underground laboratories. Since May 2007 Borexino is taking data. The achieved radiopurity and the statistics collected up to now allow to study the smaller solar neutrino fluxes from the pep fusion process and the CNO cycle. The main background source is 11C induced by the in-sito muon flux. In 95% of cases a neutron is released by the parent 12C. The 11C-candidates can be tagged on an event-by-event basis by looking at the following threefold coincidence: (1) the parent muon, (2) the 2.2 MeV gamma-ray from neutron capture on proton and (3) the decay of 11C. The method is discussed including the tagging of 11C and the muon track reconstruction. The strategy for the analysis of pep and CNO neutrinos is presented.