UHE Cosmic Rays and Neutrinos Showering on Planet Edges

Abstract

Ultra High Energy (UHE) Cosmic Rays, UHECR, may graze high altitude atmosphere leading to horizontal upward air-showers. Also PeVs ν e ¯ hitting electron in atmosphere may air-shower at W− boson resonant mass. On the other side ultra high energy muon and electron neutrinos may also lead, by UHE neutrinos mass state mixing, to the rise of a corresponding UHE Tau neutrino flavor; the consequent UHE tau neutrinos, via charge current interactions in matter, may create UHE taus at horizons (Earth skimming neutrinos or Hor-taus) whose escape in atmosphere and whose consequent decay in flight, may be later amplified by upward showering on terrestrial, planetary atmospheres. Indeed because of the finite terrestrial radius R ⊕ , its thin atmosphere size ( h 0 ≃ 10 ) km, its dense crust, the UHE tau cannot extend much more than ∼ R ⊕ h 0 π / 2 ≃ 360 kilometers in air, corresponding to an energy E τ ⊕ ≃ 7.2 EeV , near but below GZK cut-off ones; on the contrary Jupiter (or even Saturn) may offer a wider, less dense and thicker gaseous layer at the horizons where Tau may loose little energy, travel longer before decay and rise and shower at E ν τ ≃ 4 − 6 ⋅ 10 19 eV or ZeV extreme energy. Also solar atmosphere may play a role, but unfortunately tau-showers secondaries maybe are too noisy to be disentangled, while Jupiter atmosphere, or better, Saturn one, may offer a clearer imprint for GZK (and higher Z-Burst) Tau showering, well below the horizons edges.