Аннотация:To study EAS cores (beams of most energetic particles near the shower axis) at E0 ≳ 10^15 eV(√s ≳ 2 TeV), which carry the most valuable information about the types of primary particles andthe characteristics of their interactions in the atmosphere, a new set of detectors has been developed,including a high-altitude ionization calorimeter “ADRON-55”, located at a high-altitude scientificstation on the Tien Shan. The first results of modeling the development of EAS from primary protons,main groups of nuclei and hypothetical strangelets at various energies, related to measurements withthe “ADRON-55” calorimeter, are presented.