Nucleus - Air Interactions for Extensive Air Showers Experiments at Ultrahigh Energies

The HIJING and VENUS models of relativistic hadron-nucleus and nucleus-nucleus collisions are used to study interactions of proton and nuclei with nitrogen, specific for the extensive air shower developments initiated by cosmic rays in the atmosphere. The transverse energy,transverse momenta and secondary particles produced spectra as well as their energy and mass dependence were investigated in detail. Results are presented with particular emphasis on the contributions of minijets in HIJING model and validity of superposition models in this energy range .