New variables for neutrino oscillation diagnostics at SuperKamiokande and the Sudbury Neutrino Observatory

The SuperKamiokande Collaboration has presented results on the observation of solar neutrinos. The Sudbury Neutrino Observatory (SNO) is also expected to go on-line in the near future. We propose several new variables, insensitive to the absolute Aux of the initial solar neutrino beam, which probe the shape of the observed spectrum at these experiments and can sensitively signal neutrino oscillations. One class of such variables involves normalized moments of the distributions recorded at the two facilities while another variable, specific to SNO, depends on the integrated charged and neutral current signals. The utility of these variables in the context of supernova neutrinos, both from the collapse epoch and the post-bounce era, is also emphasized. It is shown that, notwithstanding the imprecise nature of the information about the initial neutrino spectra from a supernova, oscillations can be detected using these variables and it will be possible to distinguish between the alternatives of oscillation to a sequential neutrino vis-a-vis that to a sterile neutrino. [S0556-2821(99)06013-0].