In the frame of the assumption of only two-neutrino mixing, in the plane vs , the main parameters of the oscillations, two regions are still allowed for MSW by the present experimental results: one at Small Mixing Angle (SMA) and the second one at Large Mixing Angle (LMA). These two zones are 90 C.L. regions around two points, which represent the Best Fit Values. A third zone exists, at 99 C.L. at low and large mixing angle.
Similarly for the Vacuum Oscillation a large region is still allowed, around a Best Fit value.
For both the oscillations: Vacuum Oscillation and MSW the 7Be region is crucial. For the oscillations in matter in the SMA region the 7Be neutrino flux is much more reduced than the 8B flux. This is true also in the LMA, even if the effect is not so strong.
For the oscillation in vacuum the modulation wavelength is very short in the pp neutrino region, with the consequence that the effect appears to be averaged. In the high energy range of the solar neutrino spectrum the wavelength is larger than the distance Sun-Earth and the effect cannot be detected. Finally at the 7Be neutrino energy, the Sun-Earth distance is just few times the wavelength .
Evidence of the neutrino oscillation can be obtained: