Concept and analysis for a 1 - 100 peV tau neutrino observatory

The IceCube Neutrino observatory has discovered an astrophysical neutrino flux in the energy range >1 TeV with their highest energy event ~3 PeV. Although IceCube has excellent muon flavor identification, their ability to identify tau neutrinos is highly limited. We present a concept for observing the tau neutrino flux in the 1-100 PeV range, where a flux is guaranteed and its observation would give further support to the astrophysical origin of the IceCube flux. The design of the observatory requires an acceptance hA?i >400 m² sr×( _PeV^E )^1.5 to match the ~1 PeV IceCube all-flavor event rate in tau neutrinos provided a ?_e: ?_µ: ?_t = 1: 1: 1 flavor ratio. The energy dependence of the acceptance is designed to match the IceCube best-fit spectral flux index of E^-2.5 so the spectrum is evenly sampled in the 1-100 PeV range. We present a background-free implementation with pointing resolution < 1^? to begin the era of high energy tau neutrino astronomy.