Electron capture on 8B nuclei and Superkamiokande results

The energy spectrum of recoil electrons from solar neutrino scattering, as observed by Superkamiokande, is deformed with respect to that expected from SSM calculations. We considered ν−e scattering from neutrinos produced by the electron-capture on 8B nuclei, e−+8B→8Be∗+νe, as a possible explanation of the spectral deformation. A flux ΦeB≃104 cm−2 s−1 could account for Superkamiokande solar neutrino data. However this explanation is untenable, since the theoretical prediction, ΦeB=(1.3±0.2) cm−2 s−1, is smaller by four orders of magnitude.