[en] Results are reported from the complete salt phase of the Sudbury Neutrino Observatory experiment in which NaCl was dissolved in the ²H₂O (''D₂O'') target. The addition of salt enhanced the signal from neutron capture as compared to the pure D₂O 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 10⁶cm^-2s^-1, the total flux of active-flavor neutrinos from ⁸B decay in the Sun is found to be 4.94_-0.21^+0.21(stat)_-0.34^+0.38(syst) and the integral flux of electron neutrinos for an undistorted ⁸B spectrum is 1.68_-0.06^+0.06(stat)_-0.09^+0.08(syst); the signal from (ν_x,e) elastic scattering is equivalent to an electron-neutrino flux of 2.35_-0.22^+0.22(stat)_-0.15^+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 Δm²=(8.0_-0.4^+0.6)x10^-5 eV² and θ=33.9_-2.2^+2.4 degrees

[en] Upper limits on the ν_e flux at the Sudbury Neutrino Observatory have been set based on the ν_e charged-current reaction on deuterium. The reaction produces a positron and two neutrons in coincidence. This distinctive signature allows a search with very low background for ν_e's from the Sun and other potential sources. Both differential and integral limits on the ν_e flux have been placed in the energy range from 4-14.8 MeV. For an energy-independent ν_e→ν_e conversion mechanism, the integral limit on the flux of solar ν_e's in the energy range from 4-14.8 MeV is found to be Φ_νe≤3.4x10⁴ cm^-2 s^-1 (90% C.L.), which corresponds to 0.81% of the standard solar model ⁸B ν_e flux of 5.05x10⁶ cm^-2 s^-1, and is consistent with the more sensitive limit from KamLAND in the 8.3-14.8 MeV range of 3.7x10² cm^-2 s^-1 (90% C.L.). In the energy range from 4-8 MeV, a search for ν_e's is conducted using coincidences in which only the two neutrons are detected. Assuming a ν_e spectrum for the neutron induced fission of naturally occurring elements, a flux limit of Φ_νe≤2.0x10⁶ cm^-2 s^-1 (90% C.L.) is obtained

[en] A search has been made for sinusoidal periodic variations in the ⁸B solar neutrino flux using data collected by the Sudbury Neutrino Observatory over a 4-year time interval. The variation at a period of 1 yr is consistent with modulation of the ⁸B neutrino flux by the Earth's orbital eccentricity. No significant sinusoidal periodicities are found with periods between 1 d and 10 years with either an unbinned maximum likelihood analysis or a Lomb-Scargle periodogram analysis. The data are inconsistent with the hypothesis that the results of the recent analysis by Sturrock et al., based on elastic scattering events in Super-Kamiokande, can be attributed to a 7% sinusoidal modulation of the total ⁸B neutrino flux

[en] This article provides the complete description of results from the Phase I data set of the Sudbury Neutrino Observatory (SNO). The Phase I data set is based on a 0.65 kiloton-year exposure of ²H₂O (in the following denoted as D₂O) to the solar ⁸B neutrino flux. Included here are details of the SNO physics and detector model, evaluations of systematic uncertainties, and estimates of backgrounds. Also discussed are SNO's approach to statistical extraction of the signals from the three neutrino reactions (charged current, neutral current, and elastic scattering) and the results of a search for a day-night asymmetry in the ν_e flux. Under the assumption that the ⁸B spectrum is undistorted, the measurements from this phase yield a solar ν_e flux of φ(ν_e)=1.76_-0.05^+0.05(stat.)_-0.09^+0.09(syst.)x10⁶ cm^-2 s^-1 and a non-ν_e component of φ(ν_μτ)=3.41_-0.45^+0.45(stat.)_-0.45^+0.48(syst.)x10⁶ cm^-2 s^-1. The sum of these components provides a total flux in excellent agreement with the predictions of standard solar models. The day-night asymmetry in the ν_e flux is found to be A_e=7.0±4.9(stat.)_-1.2^+1.3%(syst.), when the asymmetry in the total flux is constrained to be zero.

[en] Results are reported on the measurement of the atmospheric neutrino-induced muon flux at a depth of 2 kilometers below the Earth's surface from 1229 days of operation of the Sudbury Neutrino Observatory (SNO). By measuring the flux of through-going muons as a function of zenith angle, the SNO experiment can distinguish between the oscillated and unoscillated portion of the neutrino flux. A total of 514 muonlike events are measured between -1≤cosθ_zenith≤0.4 in a total exposure of 2.30x10¹⁴ cm² s. The measured flux normalization is 1.22±0.09 times the Bartol three-dimensional flux prediction. This is the first measurement of the neutrino-induced flux where neutrino oscillations are minimized. The zenith distribution is consistent with previously measured atmospheric neutrino oscillation parameters. The cosmic ray muon flux at SNO with zenith angle cosθ_zenith>0.4 is measured to be (3.31±0.01(stat)±0.09(sys))x10^-10 μ/s/cm².

[en] The Sudbury Neutrino Observatory is a 1000 T D₂O Cerenkov detector that is sensitive to ⁸B solar neutrinos. The energy, radius, and direction with respect to the sun is measured for each neutrino event; these distributions are used to separately determine the rates of the charged current, neutral current and electron scattering reactions of neutrinos on deuterium. Assuming an undistorted ⁸B spectrum, the ν_e component of the ⁸B solar flux is phi_e = 1.76^+0.05_-0.05(stat.)^+0.09_-0.09 (syst.) x 10⁶ cm^-2s^-1 based on events with a measured kinetic energy above 5 MeV. The non-ν_e component is phi_μτ 3.41^+0.45_-0.45(stat.)^+0.48_-0.45 (syst.) x 10⁶ cm^-2s^-1, 5.3σ greater than zero, providing strong evidence for solar ν_e flavor transformation. The total flux measured with the NC reaction is phi_NC = 5.09^+0.044_-0.43(stat.)^+0.46_-0.43 (sy st.) x 10⁶ cm^-2s^-1, consistent with solar models. The night minus day rate is 14.0% ± 6.3%^+1.5_-1.4% of the average rate. If the total flux of active neutrinos is additionally constrained to have no asymmetry, the ν_e asymmetry is found to be 7.0% ± 4.9%^+1.3_-1.2%. A global solar neutrino analysis is terms of matter-enhanced oscillations of two active flavors strongly favors the Large Mixing Angle (LMA) solution

[en] The Sudbury Neutrino Observatory (SNO) is a water imaging Cherenkov detector. Its usage of 1000 metric tons of D₂O as target allows the SNO detector to make a solar-model independent test of the neutrino oscillation hypothesis by simultaneously measuring the solar ν_e flux and the total flux of all active neutrino species. Solar neutrinos from the decay of ⁸B have been detected at SNO by the charged-current (CC) interaction on the deuteron and by the elastic scattering (ES) of electrons. While the CC reaction is sensitive exclusively to ν_e, the ES reaction also has a small sensitivity to ν_μ and ν_τ. In this paper, recent solar neutrino results from the SNO experiment are presented. It is demonstrated that the solar flux from ⁸B decay as measured from the ES reaction rate under the no-oscillation assumption is consistent with the high precision ES measurement by the Super-Kamiokande experiment. The ν_e flux deduced from the CC reaction rate in SNO differs from the Super-Kamiokande ES results by 3.3σ. This is evidence for an active neutrino component, in additional to ν_e, in the solar neutrino flux. These results also allow the first experimental determination of the total active ⁸B neutrino flux from the Sun, and is found to be in good agreement with solar model predictions

[en] The Sudbury Neutrino Observatory (SNO) has precisely determined the total active (v_x)⁸B solar neutrino flux without assumptions about the energy dependence of the v_e survival probability. The measurements were made with dissolved NaCl in the heavy water to enhance the sensitivity and signature for neutral-current interactions. The flux is found to be 5.21+-0.27 (stat)+-0.38(syst)x10^-6 cm^-2s^-1, in agreement with previous measurements and standard solar models. A global analysis of these and other solar and reactor neutrino results yields Δm² = 7.1^+1.2_-0.6 x 10^-5 eV² and θ 32.5^+2.4_-2.3 degrees. Maximal mixing is rejected at the equivalent of 5.4 standard deviations

[en] A search has been made for neutrinos from the hep reaction in the Sun and from the diffuse supernova neutrino background (DSNB)using data collected during the first operational phase of the Sudbury Neutrino Observatory, with an exposure of 0.65 kilotons-years. For the hep neutrino search, two events are observed in the effective electron energy range of 14.3 MeV< T_eff<20 MeV where 3.1 background events are expected. After accounting for neutrino oscillations, an upper limit of 2.3 x 104 cm-2s-1 at the 90 percent confidence level is inferred on the integral total flux of hep neutrinos. For DSNB neutrinos, no events are observed in the effective electron energy range of 21 MeV< T_eff<35 MeV and, consequently, an upper limit on the nu e component of the DSNB flux in the neutrino energy range of 22.9 MeV< E nu<36.9 MeV of 70 cm-2-1 is inferred at the 90 percent confidence level. This is an improvement by a factor of 6.5 on the previous best upper limit on the hep neutrino flux and by two orders of magnitude on the previous upper limit on the nu e component of the DSNB flux

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