Towards survey of astronomical tau neutrino sources

Abstract

The recent observation of PeV astrophysical neutrino events by IceCube opens a new chapter in neutrino astronomy, calling for increased sensitivity and improved point-back ability, to probe for PeV-EeV neutrino point sources in the gap between IceCube and Auger energies. By separating ν τ → τ conversion from τ-shower generation, the Earth-skimming ν τ method allows for huge target mass and detection volume simultaneously. The Ashra-1 detector, in operation up Mauna Loa on Hawaii Big Island, has demonstrated the feasibility in a 1 st search for ν τ from a GRB. With design based on this experience, a Neutrino Telescope Array (NTA) observatory is being planned, with three site stations watching the air mass surrounded by Mauna Loa, Mauna Kea, and Hualalai, plus a central site station watching the lower night sky. Sensitivities equivalent to > 100 km 3 water and pointing accuracy of < 0.2 • can be achieved with Cherenkov-fluorescence stereoscopic observation for PeV-EeV neutrinos that is almost background-free. With the scientific goal of clear discovery and identification of astronomical ν τ sources to probe for cosmic proton accelerators, a new international collaboration is being formed.