Interpretation of the time structure of the EAS disc measured by the GREX/COVER_PLASTEX experiment

Simulation results for the time structure of the extensive air shower disc are presented and compared with data from the GREX/COVER_PLASTEX experiment. The distribution of the arrival times at various distances from the shower core and the contributions from the secondary particles to the shape of the distribution are described. The main parameters of the distribution, the mean time of arrival [tau] and the standard deviation sigma, reflect the shower disc profile and thickness. The dependence of the shower profile and thickness on the energy and mass of the primary particle initiating the shower as well as on its inclination angle is discussed. The influence of the experimental conditions on the disc profile and thickness measured by the GREX/COVER_PLASTEX experiment is analysed and a parametrization of the average profile and thickness is given. (C) 1997 Elsevier Science B.V.