|
Neutrinos produced as a product of pion decay following interactions of ultrahigh energy cosmic rays with the cosmic microwave background may have energies as high as ~1021 eV. With cross sections as high as around 10-31 cm2 at these energies, the earth is opaque to neutrinos that pass through even a few tens of thousands of g/cm2 of crust. Earth-skimming neutrinos at these energies should interact in the crust or atmosphere near the HiRes experiment and be detected as upward-going particle showers exiting the earth or atmospheric showers with very small elevation angles. In the case that a neutrino undergoes a charged-current interaction resulting in an ultrahigh energy electron, the Landau-Pomeranchuk-Migdal (LPM) effect, which is responsible for large decreases in the probability of bremsstrahlung and pair production, should permit an electromagnetic cascade to begin deep in the crust and exit the earth with enough charged particles to trigger the HiRes instrument. Below are some images and animated GIFs detailing the LPM effect in rock and in air. |
|
|
Rock Shower profile comparisons with Greisen approximation by log(E). [15] [16] [17] [18] [19] [20] [21] Animated shower profiles showing particle spectrum (E dN/dE) as a function of depth. [15] [16] [17] [18] [19] [20] [21] |
Air (sea level) Shower profile comparisons with Greisen approximation by log(E). [15] [16] [17] [18] [19] [20] [21] Animated shower profiles showing particle spectrum (E dN/dE) as a function of depth. [15] [16] [17] [18] [19] [20] [21] |
|
Air (different altitudes) Shower profiles at sea level, 1.4 km (Dugway desert floor), 5.0, 7.5, 10.0, 12.5, 15.0, and 16.0 km by log(E) [18] [19] [20] [21] |
|