Electron energy spectra, fluxes, and day-night asymmetries of boron-8 solar neutrinos from the 391-day salt phase sno data set

Author(s): Aharmim, B.; Ahmed, S.N.; Anthony, A.E.; Beier, E.W.; Bellerive, A.; Bergevin, M.; Biller, S.D.; Boger, J.; Boulay, M.G.; Bowler, M.G.; Bullard, T.V.; Chan, Y.D.; Chen, M.; Chen, X.; Cleveland, B.T.; Cox, G.A.; Currat, C.A.; Dai, X.; Dalnoki-Veress, F.; Deng, H.; Doe, P.J.; Dosanjh, R.S.; Doucas, G.; Duba, C.A.; Duncan, F.A.; Dunford, M.; Dunmore, J.A.; Earle, E.D.; Elliott, S.R.; Evans, H.C.; Ewan, G.T.; Farine, J.; Fergani, H.; Fleurot, F.; Formaggio, J.A.; Frame, K.; Frati, W.; Fulsom, B.G.; Gagnon, N.; Graham, K.; Grant, D.R.; Hahn, R.L.; Hall, J.C.; Hallin, A.L.; Hallman, E.D.; Handler, W.B.; Hargrove, C.K.; Harvey, P.J.; Hazama, R.; Heeger, K.M.; Heelan, L.; Heintzelman, W.J.; Heise, J.; Helmer, R.L.; Hemingway, R.J.; Hime, A.; Howard, C.; Howe, M.A.; Huang, M.; Jagam, P.; Jelley, N.A.; Klein, J.R.; Kormos, L.L.; Kos, M.S.; Kruger, A.; Kraus, C.; Krauss, C.B.; Krumins, A.V.; Kutter, T.; Kyba, C.C.M.; Labranche, H.; Lange, R.; Law, J.; Lawson, I.T.; Lesko, K.T.; Leslie, J.R.; Levine, I.; Loach, J.C.; Luoma, S.; MacLellan, R.; Majerus, S.; Mak, H.B.; Maneira, J.; Marino, A.D.; McCauley, N. | Abstract: Results are reported from the complete salt phase of the Sudbury Neutrino Observatory experiment in which NaCl was dissolved in the D_2O target. The addition of salt enhanced the signal from neutron capture, as compared to the pure D_2O 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 106 cm-2 s-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)+0.38_-0.34(syst) and the integral flux of electron neutrinos for an undistorted 8B spectrum is 1.68+0.06_-0.06(stat)+0.08_-0.09(syst); the signal from (nu_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 Delta m2 = (8.0+0.6_-0.4) x 10-5 eV2 and theta = 33.9 +2.4_-2.2 degrees.