Detecting Ultra High Energy Neutrinos by Upward Tau Airshowers and Gamma Flashes

Abstract

Tau Air-showers are the best trace of rarest Ultra High Energy neutrinos UHE $ν_τ$, $\barν_τ$ and $\barν_e$ at PeV and higher energy. $τ$ Air-showers may generate billion times amplified signals by their secondaries . Horizontal amplified $τ$ air-showers by $ν_τ N$ and UHE $\barν_{e} e$ at PeV emerging from mountain chain might be the most power-full imprint. Upward UHE $ν_τ N$ interaction on Earth crust at horizontal edge and from below, their consequent UHE $τ$ air-showers beaming toward high mountains should flash $γ$,$μ$,X and optical detectors on the top. Upward $τ$ air-shower may hit nearby satellite flashing them by short, hard, diluted $γ-$burst at the edge of Gamma Ray Observatory BATSE threshold. We identify these events with recent (1994) discovered upward Terrestrial Gamma Flashes (TGF) and we probed their UHE $τ$ - UHE $ν_τ$ origin. From these TGF data approximated UHE $ν_τ$ flux and $Δm_{ν_μν_τ}$ sever lower bound are derived. Partial TGF Galactic signature is also manifest within known 47 TGF events clustered within three degrees from the Galactic plane at ${\simeq 2\cdot 10^{-3}}$probability. Well known $X-γ-\mathrm{TeV}$ active galactic and extragalactic sources have found probable counterpart in TGF arrival directions. Detection of elusive UHE $ν_τ$ seem finally achieved.