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

Journal Article · Sat May 15 00:00:00 EDT 2010 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.81.055504· OSTI ID:21389069

Aharmim, B; Chauhan, D; Fleurot, F; Hallman, E D; Schwendener, M H; Virtue, C J ^[1]; Ahmed, S N; Boulay, M G; Cai, B; Chen, M; DiMarco, M; Earle, E D; Evans, H C; Ewan, G T; Guillian, E; Harvey, P J; Kormos, L L; Kos, M; Kraus, C; Leslie, J R ^[2]

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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)

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{sub eff}=3.5 MeV, the lowest analysis threshold yet achieved with water Cherenkov detector data. 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 measured using the neutral current (NC) reaction of neutrinos on deuterons, with no constraint on the {sup 8}B neutrino energy spectrum, is found to be PHI{sub NC}=5.140{sub -0.158}{sup +0.160}(stat){sub -0.117}{sup +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 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 {sup 8}B neutrino flux and the energy-dependent nu{sub e} survival probability provides a measure of the total {sup 8}B neutrino flux PHI{sub {sup 8}{sub B}}=5.046{sub -0.152}{sup +0.159}(stat){sub -0.123}{sup +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 theta{sub 12}=34.06{sub -0.84}{sup +1.16} degrees and DELTAm{sub 21}{sup 2}=7.59{sub -0.21}{sup +0.20}x10{sup -5} eV{sup 2}. The global value of PHI{sup 8}{sub B} is extracted to a precision of {sub -2.95}{sup +2.38}%. In a three-flavor analysis the best fit value of sin{sup 2}theta{sub 13} is 2.00{sub -1.63}{sup +2.09}x10{sup -2}. This implies an upper bound of sin{sup 2}theta{sub 13}<0.057 (95% C.L.).

• OSTI ID: 21389069
• Journal Information: Physical Review. C, Nuclear Physics, Vol. 81, Issue 5; Other Information: DOI: 10.1103/PhysRevC.81.055504; (c) 2010 The American Physical Society; ISSN 0556-2813
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
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CHARGED CURRENTS
CHERENKOV COUNTERS
DECAY
DEUTERONS
ELASTIC SCATTERING
ELECTRON NEUTRINOS
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