Longitudinal development of muons in large air showers observed at 5200 m above sea level

Abstract
The longitudinal development of muons at atmospheric depths between 200 and 700 g cm-2 has been studied by measuring the arrival time distributions of muons in air showers with primary energies from 1*1017 to a few times 1019 eV observed at Mount Chacaltaya. These arrival time distributions are consistent within those expected from very high multiplicity models of nuclear interactions, whether produced by primary protons or heavy nuclei. The longitudinal development of muons determined from equi-intensity cuts of muon size spectra of air showers is also consistent with the predictions of these models. However, the longitudinal developments of electrons expected from such models show much faster attenuation than is observed. A two-component model of air showers is proposed to explain this apparent discrepancy.