ENERGY DISSIPATION OF HADRONIC INTERACTIONS WELL ABOVE COLLIDER ENERGIES VIEWED FROM FLY'S EYE DATA ON DEPTHS OF SHOWER MAXIMA

Abstract

Using the depths of shower maxima, as measured by Fly's Eye experiment,we study the energy dissipation of hadronic showers resulting from cosmic interactions at energies between 3×1017 eV and 1019 eV. We place, based on Fly's Eye data, a set of constraints on the expected depths of shower maxima for proton-initiated showers, disentangling the hadronic interaction features from the cosmic ray composition. It is shown that in the energy region substantially above collider energies, only Monte Carlo simulations using hadronic interaction models characterized by a strong energy dissipation predict the depths of shower maxima that are consistent with this set of constraints. Between the two equally good fitsof the energy dependences of cross-section and multiplicity at collider energies — the power law and log-square law, we find that the cosmic ray data favor the power law above collider energies. The Feynman scaling in the fragmentation region above collider energies is valid only if the cross-section for inelastic hadron–air–nucleus interactions increases much more rapidly than the trend established at accelerator energies. The multiple nucleon interaction picture appears to be plausible for hadron–nucleus interactions.