Propagation of Extremely High Energy Leptons in the Earth

摘要

It has been claimed that underground neutrino telescopes such as AMANDA and IceCube have detection capability of not only PeV neutrinos but EeV-ZeV neutrinos which are possibly generated by the GZK mechanism associated with the Highest Energy Cosmic Rays.The accurate calculations on propagation of neutrinos and produced muons and taus in the Earth is inevitable for realistic evaluation of such Extremely High Energy (EHE) neutrino detection possibilities,however.The relevant interactions involving EHE neutrinos and charged leptons include charged-current interactions contributing to charged lepton disappearance and the photo-nuclear interactions,both of which has not been considered or only evaluated by the cross sections without accounting newly available data of the photon-nucleon collisions.Here we present the results of the detailed numerical calculations concerning particle propagations at EHE energies (EeV or greater).We use the GZK neutrino flux as a benchmark and show the resultant energy spectra of EHE neutrinos after their propagation in the Earth as well as the generated secondary leptons.The expected event rate above 0.1 EeV by a km cube detector is approx 1 event/year.