Measurement of day and night neutrino energy spectra at SNO and constraints on neutrino mixing parameters.

The Sudbury Neutrino Observatory(SNO) has measured dayand night solar neutrinoenergy spectra and rates. For charged currentevents, assuming an undistorted 8 B spectrum, the night minus day rate is 14.0% ′ 6.3% + 1 . 5 - 1 . 4 % of the average rate. If the total flux of active neutrinosis additionally constrained to have no asymmetry, the v e asymmetry is found to be 7.0% ′ 4.9% + 1 . 3 - 1 . 2 %. A global solar neutrinoanalysis in terms of matter-enhanced oscillations of two active flavors strongly favors the large mixing angle solution.