Low-energy-threshold analysis of the Phase I and Phase II data sets of the Sudbury Neutrino Observatory

Results are reported from a joint analysis of Phase I and Phase II data from the Sudbury Neutrino Observatory. The effective electron kinetic energy threshold used is Teff=3.5 MeV, the lowest analysis threshold yet achieved with water Cherenkov detectordata. In units of 106 cm-2 s-1, the total flux of active-flavor neutrinosfrom 8B decay in the Sun measured using the neutral current(NC) reaction of neutrinoson deuterons, with no constraint on the 8B neutrinoenergy spectrum, is found to be FNC=5.140-0.158+0.160(stat)-0.117+0.132(syst). These uncertainties are more than a factor of 2 smaller than previously published results. Also presented are the spectra of recoil electrons from the charged currentreaction of neutrinoson deuterons and the elastic scattering of electrons. A fit to the Sudbury Neutrino Observatorydata in which the free parameters directly describe the total 8B neutrinoflux and the energy-dependent e survival probability provides a measure of the total 8B neutrinoflux F8B=5.046-0.152+0.159(stat)-0.123+0.107(syst). Combining these new results with results of all other solar experiments and the KamLAND reactor experiment yields best-fit values of the mixing parameters of 12=34.06-0.84+1.16 degrees and m212=7.59-0.21+0.2010-5 eV2. The global value of 8B is extracted to a precision of -2.95+2.38%. In a three-flavor analysis the best fit value of sin213 is 2.00-1.63+2.0910-2. This implies an upper bound of sin213<0.057 (95% C.L.).