Multiple muons deep underground

A sample of 176723 single cosmic ray muon events, 2802 two-muon events, and 225 three-muon events have been collected and analysed to obtain muon rates adjusted for an equivalent detector having a constant normal area of 20 m2. The measurements span the range of zenith angles between 40 and 70 degrees and slant depths of standard rock between 2*105g cm-2 and 6.5*105 g cm-2, corresponding to minimum muon energies at ground level of between 750 and 8000 GeV. A comparison of these measurements with those predicted by a conservative model based upon extrapolation from results at lower energies is given in the paper by Adcock et al. (see ibid. vol. 4, 276, 1971).