A new calculation of Earth-skimming very- and ultra-high energy tau neutrinos. (arXiv:1908.03603v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Reno_M/0/1/0/all/0/1">Mary Hall Reno</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Venters_T/0/1/0/all/0/1">Tonia M. Venters</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Krizmanic_J/0/1/0/all/0/1">John F. Krizmanic</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Anchordoqui_L/0/1/0/all/0/1">Luis A. Anchordoqui</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Guepin_C/0/1/0/all/0/1">Claire Guepin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Olinto_A/0/1/0/all/0/1">Angela V. Olinto</a> (for the POEMMA Collaboration)

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. We quantify the
experimental detection capability based on our calculation, including using the
Probe of Extreme Multi-Messenger Astrophysics (POEMMA) concept study response
parameters for optical air Cherenkov detection. These case studies are used to
illustrate the features and uncertainties in upward tau air shower detection.

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. We quantify the
experimental detection capability based on our calculation, including using the
Probe of Extreme Multi-Messenger Astrophysics (POEMMA) concept study response
parameters for optical air Cherenkov detection. These case studies are used to
illustrate the features and uncertainties in upward tau air shower detection.

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