Properties of air showers and the nature of the primary cosmic-ray spectrum

Calculations of the longitudinal development of air showers initiated by protons and heavy primaries are made. A comparison of the characteristics indicates that the separation of the heavy nucleus and proton-initiated showers is difficult. The size dependence of the number of muons of energy greater than 1, 220, and 660 GeV is shown to be consistent with the existence of a rigidity cutoff of galactic cosmic rays at ~105 GV, followed by an extragalactic component of protons at higher energies. The lateral distribution of 220-GeV muons in air showers is shown to be consistent with a mean transverse momentum of less than 1 GeV per pion