Simulation of cascades caused by UHE and EHE neutrinos in dense media

Abstract

A method of simulation of particle cascades induced by ultra-high (>10$^{15}$ eV) and extremely high (>10$^{18}$ eV) energy neutrinos in water or other dense medium has been elaborated. The lateral spread of high-energy particles in cascades due to Coulomb scattering is negligible. So it is possible to use an approximation of the one-dimensional development of the UHE (or EHE) cascade if energies of particles in it higher than 10-100 GeV. An original program of the one-dimensional development of UHE and EHE cascades in dense media taking into account fluctuations and the Landau-Pomeranchuk-Migdal effect has been elaborated. The GEANT4 package has been used when particle energies are below 1000 GeV, for example, or less to calculate correctly the longitudinal distribution of an energy deposition by charge particles in a cascade. In advance the library of longitudinal characteristics of cascades was calculated. When a particle with the energy E which is below the threshold energy (E<1000 GeV or E<10$^6$ GeV) appears in the basic Monte Carlo program, the longitudinal distribution of an energy deposition induced by it was taken from the library and was added into the corresponding places of the basic distribution. The results of simulation of cascades in a dense medium can be used for calculations of acoustical or radio signals.