A new approach to EAS investigations in the energy region 1015–1019 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.