Mass signature of supernova {nu}{sub {mu}} and {nu}{sub {tau}} neutrinos in the Sudbury Neutrino Observatory

Core-collapse supernovae emit of order 10{sup 58} neutrinos and antineutrinos of all flavors over several seconds, with average energies of 10{endash}25 MeV. In the Sudbury Neutrino Observatory (SNO), which begins operation this year, neutrinos and antineutrinos of all flavors can be detected by reactions which break up the deuteron. For a future Galactic supernova at a distance of 10 kpc, several hundred events will be observed in SNO. The {nu}{sub {mu}} and {nu}{sub {tau}} neutrinos and antineutrinos are of particular interest, as a test of the supernova mechanism. In addition, it is possible to measure or limit their masses by their delay (determined from neutral-current events) relative to the {bar {nu}}{sub e} neutrinos (determined from charged-current events). Numerical results are presented for such a future supernova as seen in SNO. Under reasonable assumptions, and in the presence of the expected counting statistics, a {nu}{sub {mu}} or {nu}{sub {tau}} mass down to about 30 eV can be simply and robustly determined. If zero delay is measured, then the mass limit is {ital independent} of the distance D. At present, this seems to be the best possibility for direct determination of a {nu}{sub {mu}} or {nu}{sub {tau}} mass within the cosmologically interestingmore » range. We also show how to separately study the supernova and neutrino physics, and how changes in the assumed supernova parameters would affect the mass sensitivity. {copyright} {ital 1998} {ital The American Physical Society}« less