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This paper details the solar neutrino analysis of the 385.17-day phase-III data set acquired by the Sudbury Neutrino Observatory (SNO). An array of He-3 proportional counters was installed in the heavy-water target to measure precisely the rate of neutrino-deuteron neutral-current interactions. This technique to determine the total active B-8 solar neutrino flux was largely independent of the methods employed in previous phases. The total flux of active neutrinos was measured to be 5.54(-0.31)(+0.33)(stat.)(-0.34)(+0.36)(syst.) x 10(6) cm(-2) s(-1), consistent with previous measurements and standard solar models. A global analysis of solar and reactor neutrino mixing parameters yielded the best-fit values of Delta m(2) = 7.59(-0.21)(+0.19) x 10(-5) eV(2) and theta = 34.4(-1.2)(+1.3) degrees. DOI: 10.1103/PhysRevC.87.015502

This article provides the complete description of resultsfrom the Phase I data set of the Sudbury Neutrino Observatory (SNO). ThePhase I data set is based on a 0.65 kt-year exposure of heavy water tothe solar 8B neutrino flux. Included here are details of the SNO physicsand detector model, evaluations of systematic uncertainties, andestimates of backgrounds. Also discussed are SNO's approach tostatistical extraction of the signals from the three neutrino reactions(charged current, neutral current, and elastic scattering) and theresults of a search for a day-night asymmetry in the ?e flux. Under theassumption that the 8B spectrum is undistorted, the measurements fromthis phase yield a solar ?e flux of ?(?e) =1.76+0.05?0.05(stat.)+0.09?0.09 (syst.) x 106 cm?2 s?1, and a non-?ecomponent ?(? mu) = 3.41+0.45?0.45(stat.)+0.48?0.45 (syst.) x 106 cm?2s?1. The sum of these components provides a total flux in excellentagreement with the predictions of Standard Solar Models. The day-nightasymmetry in the ?e flux is found to be Ae = 7.0 +- 4.9 (stat.)+1.3?1.2percent (sys.), when the asymmetry in the total flux is constrained to bezero.

Results are reported from the complete salt phase of the Sudbury Neutrino Observatory experiment in which NaCl was dissolved in the {sup 2}H{sub 2}O (''D{sub 2}O'') target. The addition of salt enhanced the signal from neutron capture as compared to the pure D{sub 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{sup 6}cm{sup -2}s{sup -1}, the total flux of active-flavor neutrinos from {sup 8}B decay in the Sun is found to be 4.94{sub -0.21}{sup +0.21}(stat){sub -0.34}{sup +0.38}(syst) and the integral flux of electron neutrinos for an undistorted {sup 8}B spectrum is 1.68{sub -0.06}{sup +0.06}(stat){sub -0.09}{sup +0.08}(syst); the signal from ({nu}{sub x},e) elastic scattering is equivalent to an electron-neutrino flux of 2.35{sub -0.22}{sup +0.22}(stat){sub -0.15}{sup +0.15}(syst). These results are consistent with those expected for neutrino oscillations with the so-called large mixing angle parameters and also with an undistorted spectrum. A search for matter-enhancement effects in the Earth through a possible day-night asymmetry in the charged-current integral rate is consistent with no asymmetry. Including results from other experiments, the best-fit values for two-neutrino mixing parameters are {delta}m{sup 2}=(8.0{sub -0.4}{sup +0.6})x10{sup -5}more » eV{sup 2} and {theta}=33.9{sub -2.2}{sup +2.4} degrees.« less

The reaction $^{32}\mathrm{S}(^{14}\mathrm{N}, \mathrm{pn}\ensuremath{\gamma})^{44}\mathrm{Ti}$ has been studied with a view to populating high spin states in $^{44}\mathrm{Ti}$. In singles and $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidence experiments $\ensuremath{\gamma}$-ray transitions in the ground state band and a negative parity band are seen and three levels connected to the ground state band, at 6508, 7671, and 8040 keV, are inferred. Angular distributions are consistent with stretched cascades. The lifetime of the 7671-keV level, presumed ${10}^{+}$, has been determined by the attenuated Doppler-shift method to be 2.7 \ifmmode\pm\else\textpm\fi{} 0.5 ps. A comparison of the present reaction with the recently reported $^{28}\mathrm{Si}(^{19}\mathrm{F}, p2n\ensuremath{\gamma})^{44}\mathrm{Ti}$ reaction is made and a method for predicting the propensity of these types of reaction to feed high spin states is proposed. $\mathrm{An}{(\mathrm{fp})}^{4}$ shell model calculation of yrast levels up to $J=12$ has been made.

A reported splitting of the lowest T = 2 strength in /sup 44/Ti has been confirmed by examining resonances in the /sup 40/Ca(..cap alpha.., ..gamma..) /sup 44/Ti reaction at excitation energies in the region of 9.28--9.36 MeV. A level at 9298 +- 2 keV in /sup 44/Ti is found to have ..gamma..-decays to the 1/sup +/, T = 1 level at 7216 keV and to a T = 0 level at 3756 keV. The former transition is attributed to a T = 2 component in the 9298 keV level, with, however, the main T = 2 strength remaining in the level at 9338 +- 2 keV, as reported previously. Evidence is presented for a weak (9338 ..-->.. 3756), ..delta..T = 2 transition in addition to the dominant (9338 ..-->.. 7216), ..delta..T = 1 ..gamma..-decay branch. The two levels at 9298 and 9338 keV are interpreted as an isospin-mixed doublet. The perturbing matrix element is estimated to be 16 +- 3 keV, and the unperturbed T = 2 state to lie at 9330 +- 4 keV.

Evidence on the lifetimes and spins of the bound levels of /sup 44/Ti as obtained from the /sup 40/Ca(..cap alpha..,..gamma..)/sup 44/Ti reaction is presented. Lifetimes were obtained by the Doppler shift attenuation method, and spins from angular distribution and transition strength arguments. Weak ..gamma..-ray branches have been established in ..gamma..-..gamma.. coincidences between Ge(Li) and NaI(Tl) detectors. Present information supports the interpretation of most of the bound levels of /sup 44/Ti in terms of rotational-like bands.

The extrapolated end-point of the tritium beta spectrum has been measured in a tritium-implanted Si(Li) detector for which the radiation damage has been kept small. The result is 18577 +- 7 eV. Adding the maximum recoil energy, the /sup 3/H-/sup 3/He atomic mass difference is taken to be 18580 +- 7 eV.

A formalism is presented for extracting isospin mixing in the compound nucleus from a comparison of Ericson fluctuations in the cross section of mirror reactions. Some experimental aspects of the comparison are also discussed.

The decay of /sup 50/V has been studied with a low-background, three-crystal intrinsic Ge detector operating in a salt mine. The partial half-life for electron-capture decay to the first excited state of /sup 50/Ti has been estimated to be (2.05+-0.49)/times/10/sup 17/ yr, and the partial half-life for ..beta../sup /minus// decay to the first excited state of /sup 50/Cr has been estimated to be (8.2/sub /minus/3.1//sup +13.1/)/times/10/sup 17/ yr.

The half-life of tritium implanted into a Si(Li) x-ray detector has been determined to be 12.32\ifmmode\pm\else\textpm\fi{}0.03 yr by following the decay for about 5.5 years. Using a recently determined \ensuremath{\beta}-decay end-point energy for the same system, the product (${G}_{A}$/${G}_{V}$)〈\ensuremath{\sigma}\ensuremath{\tau}〉 for tritium has been determined to be 2.094\ifmmode\pm\else\textpm\fi{}0.004.

An upper limit of 0.16% (one standard deviation) is placed on the $\ensuremath{\gamma}$-ray branching ratio for the $\ensuremath{\Delta}T=2$ transition from the $T=2, {0}^{+}$ level at 9338 \ifmmode\pm\else\textpm\fi{} 2 keV in $^{44}\mathrm{Ti}$ to the first excited ${2}^{+}$ level at 1083 keV. A new determination of $\frac{{\ensuremath{\Gamma}}_{\ensuremath{\alpha}}{\ensuremath{\Gamma}}_{\ensuremath{\gamma}}}{\ensuremath{\Gamma}}$ for the $T=2$ level gives 0.24 eV. The upper limit for the $\ensuremath{\Delta}T=2$ transition is shown to be consistent with shell-model estimates of isospin mixing.

A \ensuremath{\gamma}-ray peak attributed to the deexcitation of the first excited state of $^{50}\mathrm{Ti}$ has been detected from vanadium metal by a large, low background intrinsic Ge detector operating in a salt mine. The partial half-life for the electron capture decay of $^{50}\mathrm{V}$ to the first excited state of $^{50}\mathrm{Ti}$ has been estimated to be ${1.2}_{\mathrm{\ensuremath{-}}0.4}^{+0.8}$\ifmmode\times\else\texttimes\fi{}${10}^{17}$ yr. A limit on the partial half-life for ${\ensuremath{\beta}}^{\mathrm{\ensuremath{-}}}$ decay is also obtained.

The /sup 12/C(/sup 12/C,t)/sup 21/Na reaction has been studied at theta = 0/sup 0/ over an energy range from 37 to 50 MeV. Rapid fluctuations in the cross sections to individual final states were observed, but no conclusive evidence for pronounced resonant structure was observed, either at the 19.3 MeV (c.m.) anomaly or elsewhere.