Multiple muons in the Utah detector. II. Comparison with a hadronic scaling model

Abstract

Detailed predictions are made for the multiple-muon-event rates measured in the underground muon experiment at the University of Utah. In our calculations, Feynman scaling is used to project inclusive proton-nucleus particle production cross sections from 19.2-GeV accelerator measurements to the ultrahigh-energy region from 1 TeV to 10 000 TeV. The multiplicity distribution is assumed to follow Koba-Nielsen-Olesen scaling. The primary cosmic-ray spectrum and composition are extrapolated upwards from the direct measurements made at less than a few TeV. Rates are calculated for detected multiplicities $n_D=1\mathrm{}-30$ observed over a zenith angle range 30°-72° and over a depth range of 1.5×${10}^5$ ${-10\mathrm{}}^6$ g ${\mathrm{cm}}^{-2\mathrm{}}$. Good agreement between predictions and measurements has been obtained with scaling and such a simple extrapolation to higher energies of the directly measured primary spectrum and composition.