A new calculation of Earth-skimming very- and ultra-high energy tau neutrinos

Understand

Cosmic neutrinos above a PeV are produced either within astrophysical sources or when ultra-high energy cosmic rays interact in transit through the cosmic background radiation.

• Detection of these neutrinos will be essential for understanding cosmic ray acceleration, composition and source evolution.
• By using the Earth as a tau neutrino converter for upward-going extensive air showers from tau decays, balloon-borne and space-based instruments can take advantage of a large volume and mass of the terrestrial neutrino target.
• The theoretical inputs and uncertainties in determining the tau lepton exit probabilities and their translation to detection acceptance will be discussed in the context of a new calculation we have performed.