QUARK-GLUON-STRING MODEL AND EAS SIMULATION PROBLEMS AT ULTRA-HIGH ENERGIES

The reliability of model calculations is of considerable significance because at energies above those attained by accelerators only model pr edictions enable us to extract primary cosmic ray characteristics. Dif ferent phenomenological models based on the quark-gluon picture of had ron interactions are of use now as a foundation for experimental data analysis at energies >10(15) eV. In this paper we consider the present status of quark-gluon string (QGS) model with allowance made for semi hard processes and (in the framework of so advanced model) discuss exp erimental data obtained at energies 10(15) divided by 10(19) eV. In do ing so we assume mass composition following from the diffusion notions of cosmic ray propagation through the Galaxy. Some general problems o f;EAS simulation and among them the simulation of electron-photon casc ades are also discussed.