What might we learn from a future supernova neutrino signal?

Abstract

Neutrinos from a future Galactic supernova will be detected by several large underground detectors, in particular by SuperKamiokande (SK) and the Sudbury Neutrino Observatory (SNO). If, as expected, the $ν_μ$ and $ν_τ$ neutrinos have somewhat higher energy on average that the electron neutrinos, they will dominate the neutral current response. The ways to separate the neutral and charged current signals will be discussed, and the best strategy to measure the possible time delay of the neutral current events will be outlined. Given the expected count rates, one will be able to measure in this way the $ν_τ$ mass down to about 30 eV in SNO and to 50 eV in SuperKamiokande. Another application to be discussed is the supernova localization by the neutrino signal, prior to or independently of the electromagnetic signal. The accuracy with which this can be accomplished using the angular distributions of the reactions will be estimated. With two or more detectors one can, in principle, attempt triangulation based on the arrival time of the neutrinos. It will be argued that for realistic parameters this method will be very difficult and likely leads only to crude localization.