| The Super-Kamiokande neutrino detector was built with the intent to explain the long-standing apparent solar neutrino flux deficit through signatures of neutrino flavor oscillations, such as a distortion in the energy spectrum and an asymmetry in the day and night fluxes. With the absence of any such “smoking-gun” evidence, an oscillation analysis of solar neutrinos was performed using the data sample from Super-Kamiokande I (SK), Sudbury Neutrino Observatory (SNO), and all other neutrino detectors. A model-independent analysis of SK's total solar neutrino rate and SNO's solar electron-neutrino rate showed at 3.7 σ level that the apparent deficit is due to the effects of neutrino flavor oscillations. This analysis was possible because for a careful choice of energy thresholds, SK and SNO have virtually the same response to 8B solar neutrinos, whose energy spectrum is undistorted, as demonstrated by the data. By utilizing the full data sets of SK and SNO, however, the oscillation scenario is favored at 6.0 σ level, with the best-fit oscillation parameters of Δm2 = 6.3 × 10−5 eV2 and tan 2&thetas; = 0.44 (in the LMA region). The measured 8B neutrino flux is Φν = × 106 cm−2s−1 , which confirms its theoretical prediction from the Standard Solar Model. With the addition of the neutrino rates from the radiochemical experiments (gallium and chlorine), and the anti-neutrino oscillation result from KamLAND, the LMA solution is further constricted, the 8B neutrino flux is again confirmed (Φν = × 106 cm−2s −1), and the no-oscillation scenario is ruled out at more than 10 σ level. |
