A new approach to EAS investigations in the energy region 1015-1019Â eV

A new method of extensive air shower (EAS) investigations based on a new phenomenological variable-local muon density at the observation point-is discussed. It is shown that local muon density spectra are sensitive to primary spectrum shape, primary composition and hadronic interaction model. Ground level measurements of muon density spectra in a wide range of zenith angles provide the possibility to study EAS spectrum in very wide energy interval by means of a single, relatively small-size setup. New data on muon bundles obtained with Russian-Italian coordinate-tracking detector DECOR are compared with simulation results for different spectrum and interaction models.