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Title: Electron energy spectra, fluxes, and day-night asymmetries of {sup 8}B solar neutrinos from measurements with NaCl dissolved in the heavy-water detector at the Sudbury Neutrino Observatory

Abstract

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

Authors:
; ; ; ; ; ; ;  [1]; ; ; ; ; ; ; ; ; ; ; ;  [2]
  1. Department of Physics and Astronomy, Laurentian University, Sudbury, Ontario, P3E 2C6 (Canada)
  2. Department of Physics, Queen's University, Kingston, Ontario, K7L 3N6 (Canada) [and others
Publication Date:
OSTI Identifier:
20699143
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 72; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevC.72.055502; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA). SNO Collaboration
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ASYMMETRY; BORON 8; CAPTURE; CHARGED CURRENTS; COSMIC NEUTRINOS; ELASTIC SCATTERING; ELECTRON NEUTRINOS; ELECTRONS; ENERGY SPECTRA; HEAVY WATER; ISOTROPY; NEUTRINO DETECTION; NEUTRINO OSCILLATION; NEUTRINO-ELECTRON INTERACTIONS; NEUTRON REACTIONS; NUCLEAR DECAY; SODIUM CHLORIDES; SOLAR NEUTRINOS; SUDBURY NEUTRINO OBSERVATORY; WEINBERG ANGLE

Citation Formats

Aharmim, B., Fleurot, F., Hallman, E.D., Krueger, A., Luoma, S., Schwendener, M.H., Tafirout, Virtue, C.J.R., Ahmed, S.N., Chen, M., Duncan, F.A., Earle, E.D., Evans, H.C., Ewan, G.T., Fulsom, B.G., Graham, K., Hallin, A.L., Handler, W.B., Harvey, P.J., and Howard, C.. Electron energy spectra, fluxes, and day-night asymmetries of {sup 8}B solar neutrinos from measurements with NaCl dissolved in the heavy-water detector at the Sudbury Neutrino Observatory. United States: N. p., 2005. Web. doi:10.1103/PhysRevC.72.055502.
Aharmim, B., Fleurot, F., Hallman, E.D., Krueger, A., Luoma, S., Schwendener, M.H., Tafirout, Virtue, C.J.R., Ahmed, S.N., Chen, M., Duncan, F.A., Earle, E.D., Evans, H.C., Ewan, G.T., Fulsom, B.G., Graham, K., Hallin, A.L., Handler, W.B., Harvey, P.J., & Howard, C.. Electron energy spectra, fluxes, and day-night asymmetries of {sup 8}B solar neutrinos from measurements with NaCl dissolved in the heavy-water detector at the Sudbury Neutrino Observatory. United States. doi:10.1103/PhysRevC.72.055502.
Aharmim, B., Fleurot, F., Hallman, E.D., Krueger, A., Luoma, S., Schwendener, M.H., Tafirout, Virtue, C.J.R., Ahmed, S.N., Chen, M., Duncan, F.A., Earle, E.D., Evans, H.C., Ewan, G.T., Fulsom, B.G., Graham, K., Hallin, A.L., Handler, W.B., Harvey, P.J., and Howard, C.. Tue . "Electron energy spectra, fluxes, and day-night asymmetries of {sup 8}B solar neutrinos from measurements with NaCl dissolved in the heavy-water detector at the Sudbury Neutrino Observatory". United States. doi:10.1103/PhysRevC.72.055502.
@article{osti_20699143,
title = {Electron energy spectra, fluxes, and day-night asymmetries of {sup 8}B solar neutrinos from measurements with NaCl dissolved in the heavy-water detector at the Sudbury Neutrino Observatory},
author = {Aharmim, B. and Fleurot, F. and Hallman, E.D. and Krueger, A. and Luoma, S. and Schwendener, M.H. and Tafirout and Virtue, C.J.R. and Ahmed, S.N. and Chen, M. and Duncan, F.A. and Earle, E.D. and Evans, H.C. and Ewan, G.T. and Fulsom, B.G. and Graham, K. and Hallin, A.L. and Handler, W.B. and Harvey, P.J. and Howard, C.},
abstractNote = {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} eV{sup 2} and {theta}=33.9{sub -2.2}{sup +2.4} degrees.},
doi = {10.1103/PhysRevC.72.055502},
journal = {Physical Review. C, Nuclear Physics},
number = 5,
volume = 72,
place = {United States},
year = {Tue Nov 01 00:00:00 EST 2005},
month = {Tue Nov 01 00:00:00 EST 2005}
}
  • 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 {sup 2}H{sub 2}O (in the following denoted as D{sub 2}O) to the solar {sup 8}B 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 amore » day-night asymmetry in the {nu}{sub e} flux. Under the assumption that the {sup 8}B spectrum is undistorted, the measurements from this phase yield a solar {nu}{sub e} flux of {phi}({nu}{sub e})=1.76{sub -0.05}{sup +0.05}(stat.){sub -0.09}{sup +0.09}(syst.)x10{sup 6} cm{sup -2} s{sup -1} and a non-{nu}{sub e} component of {phi}({nu}{sub {mu}}{sub {tau}})=3.41{sub -0.45}{sup +0.45}(stat.){sub -0.45}{sup +0.48}(syst.)x10{sup 6} cm{sup -2} s{sup -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 {nu}{sub e} flux is found to be A{sub e}=7.0{+-}4.9(stat.){sub -1.2}{sup +1.3}%(syst.), when the asymmetry in the total flux is constrained to be zero.« less
  • The Sudbury Neutrino Observatory (SNO) used an array of {sup 3}He proportional counters to measure the rate of neutral-current interactions in heavy water and precisely determined the total active ({nu}{sub x}) {sup 8}B solar neutrino flux. This technique is independent of previous methods employed by SNO. The total flux is found to be 5.54{sub -0.31}{sup +0.33}(stat){sub -0.34}{sup +0.36}(syst)x10{sup 6} cm{sup -2} s{sup -1}, in agreement with previous measurements and standard solar models. A global analysis of solar and reactor neutrino results yields {delta}m{sup 2}=7.59{sub -0.21}{sup +0.19}x10{sup -5} eV{sup 2} and {theta}=34.4{sub -1.2}{sup +1.3} degrees. The uncertainty on the mixing anglemore » has been reduced from SNO's previous results.« less
  • No abstract prepared.
  • A search has been made for sinusoidal periodic variations in the {sup 8}B 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 {sup 8}B 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 scatteringmore » events in Super-Kamiokande, can be attributed to a 7% sinusoidal modulation of the total {sup 8}B neutrino flux.« less
  • We have performed three searches for high-frequency signals in the solar neutrino flux measured by the Sudbury Neutrino Observatory, motivated by the possibility that solar g-mode oscillations could affect the production or propagation of solar {sup 8}B neutrinos. The first search looked for any significant peak in the frequency range 1-144 day{sup -1}, with a sensitivity to sinusoidal signals with amplitudes of 12% or greater. The second search focused on regions in which g-mode signals have been claimed by experiments aboard the Solar and Heliospheric Observatory satellite, and was sensitive to signals with amplitudes of 10% or greater. The thirdmore » search looked for extra power across the entire frequency band. No statistically significant signal was detected in any of the three searches.« less