Echo Technique to Distinguish Flavors of Astrophysical Neutrinos
  The flavor composition of high-energy astrophysical neutrinos is a rich observable. However, present analyses cannot effectively distinguish particle showers induced by $\nu_e$ versus $\nu_\tau$. We show that this can be accomplished by measuring the intensities of the delayed, collective light emission from muon decays and neutron captures, which are, on average, greater for $\nu_\tau$ than for $\nu_e$. This new technique would significantly improve tests of the nature of astrophysical sources and of neutrino properties. We discuss the promising prospects for implementing it in IceCube and other detectors. 
Shirley Weishi Li, Mauricio Bustamante, John F. Beacom (Ohio State   University)
astro-ph.HE hep-ph