Three-dimensional simulation of air showers. Core structures

Abstract

Three-dimensional Monte Carlo simulations of extensive air showers were made with a model of nuclear interaction based essentially on the two-fireball model. Monte Carlo simulations were tried with primary protons of energy 10⁶ and 2.5 × 10⁵ GeV. Various quantities related to electrons, nuclear-active particles, and muons were obtained which enable us to get detailed information on the development of individual showers.Among various features so far simulated, those of core structures, in particular, are presented in great detail and discussed in connection with shower development. Within the framework of the fireball model the following main features were noted for the formation of multiple electron cores. The fraction of multicored events is strongly dependent on the primary energy, and decreases considerably with increasing height. These events were all initiated at high altitudes and none of them had high-density peaks with a separation of a few or more meters. High-energy nuclear particles play an important role in producing multicored events, but none of the peaks in multi-cored events were produced by a single γ ray.These features, in comparison with the experimental results, require the introduction of a large mean transverse momentum for nucleons, particularly at high energies [Formula: see text]. It seems likely that it increases with energy.