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 ${n}_{D}=1\ensuremath{-}30$ observed over a zenith angle range 30\ifmmode^\circ\else\textdegree\fi{}-72\ifmmode^\circ\else\textdegree\fi{} and over a depth range of 1.5\ifmmode\times\else\texttimes\fi{}${10}^{5}$${\ensuremath{-}10}^{6}$ g ${\mathrm{cm}}^{\ensuremath{-}2}$. 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.