ИСТИНА

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 is described. Since the lateral spread of high-energy particles in cascades due to Coulomb scattering is negligible, it is possible to use a one-dimensional approximation for the development of the UHE (or EHE) cascade if the energies of the particles in the cascade exceed 10-100 GeV. Under this approximation, 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 developed. The GEANT4 package has been used when particle energies are below 1000 GeV to calculate correctly the longitudinal distribution of energy deposition by charged particles in a cascade. Before program execution, a library of the longitudinal characteristics of cascades is produced. When particles with energy E below the threshold energy (E < 1000 GeV or E < 10**6 GeV) appear in the basic Monte Carlo program, the longitudinal distribution of energy deposition induced by it was drawn from the library. Our results for simulation of cascades in a dense medium can be used for calculations of acoustical or radio signals.