Supernova Neutrinos and the Neutrino Masses

TL;DR

This paper discusses how observations of neutrinos from a future galactic supernova could be used to measure or limit the masses of muon and tau neutrinos down to about 30 eV, providing a promising method for direct neutrino mass determination.

Contribution

It introduces a method to measure muon and tau neutrino masses using supernova neutrino delays in the SNO detector, with numerical results demonstrating its feasibility.

Findings

Potential to measure neutrino masses down to 30 eV

Robust technique based on neutrino delay analysis

Applicable to future galactic supernova observations

Abstract

Core-collapse supernovae emit of order $10^{58}$ neutrinos and antineutrinos of all flavors over several seconds, with average energies of 10--25 MeV. In the Sudbury Neutrino Observatory (SNO), a future Galactic supernova at a distance of 10 kpc would cause several hundred events. The $\nu_\mu$ and $\nu_\tau$ 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 $\bar{\nu}_e$ 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 $\nu_\mu$ or $\nu_\tau$ mass down to about 30 eV can be simply and robustly determined. This seems to be the best technique for direct measurement of these masses.