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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 T eff = 3.5 MeV, the lowest analysis threshold yet achieved with water Cherenkov detector data. In units of 10 6 cm −2 s −1 , the total flux of active-flavor neutrinos from 8 B decay in the Sun measured using the neutral current (NC) reaction of neutrinos on deuterons, with no constraint on the 8 B neutrino energy spectrum, is found to be NC = 5.140 +0.160 −0.158 (stat) +0.132 −0.117 (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 current reaction of neutrinos on deuterons and the elastic scattering of electrons. A fit to the Sudbury Neutrino Observatory data in which the free parameters directly describe the total 8 B neutrino flux and the energy-dependent ν e survival probability provides a measure of the total 8

Results are reported from the complete salt phase of the Sudbury Neutrino Observatory experiment in which NaCl was dissolved in the D 2 O target. The addition of salt enhanced the signal from neutron capture, as compared to the pure D 2 O detector. By making a statistical separation of charged-current events from other types based on event-isotropy criteria, the effective electron recoil energy spectrum has been extracted. In units of 10 6 cm −2 s −1 , the total flux of active-flavor neutrinos from 8 B decay in the Sun is found to be 4.94

The Sudbury Neutrino Observatory (SNO) used an array of 3 He proportional counters to measure the rate of neutral-current interactions in heavy water and precisely determined the total active (ν x ) 8 B solar neutrino flux. This technique is independent of previous methods employed by SNO The Sudbury Neutrino Observatory [1] detects 8 B solar neutrinos through three reactions: charged-current interactions (CC) on deuterons, in which only electron neutrinos participate; neutrino-electron elastic scattering (ES), which are dominated by contributions from electron neutrinos; and neutral-current (NC) disintegration of the deuteron by neutri-

Hydrogen burning of the oxygen isotopes takes place in low-mass stars, AGB stars, and classical novae. Observations of oxygen elemental and isotopic abundances in stellar spectra or in presolar grains provide strong constraints for stellar models if reliable thermonuclear reaction rates for hydrogen burning of oxygen are available. We present the results of a new measurement of the 17 O(p,γ) 18 F reaction in the laboratory bombarding energy range of 170−530 keV. The measurement is performed with significantly higher beam intensities (I max ≈ 2 mA) compared to previous work and by employing a sophisticated γ-ray coincidence spectrometer. We measured the cross section at much lower energies than previous in-beam experiments. We also apply a novel data analysis technique that is based on the decomposition of different contributions to the measured pulseheight spectrum. Our measured strengths of the low energy resonances amount to ωγ pres (193 keV) = (1.86 ± 0.13) × 10 −6 eV and ωγ pres (518 keV) = (13.70 ± 0.96) × 10 −3 eV. For the direct capture S-factor at zero energy, we find a value of S pres DC (0) = 4.82 ± 0.41 keVb. We also present new thermonuclear rates for the 17 O+p reactions, taking into account all consistent results from previous measurements.