Observation of electromagnetic interactions of high energy muons deep underground

Abstract

The first experimental measurement of the spectrum of cascade showers produced by cosmic ray muon interactions deep underground in the transferred energy range 0.4-200 GeV has been performed by means of the NUSEX calorimeter at a depth of about 5000 hg/cm2, the average muon energy being close to 360 GeV. The spectrum of energy transfers is in good agreement with calculations based on the commonly used theoretical formulas for muon interaction cross sections and on a conservative picture of the formation of muon energy spectrum at great depths. The present data do not confirm the deficit of the cross section at low energy transfers for the 1 TeV muon energy recently reported by the CCFR Collaboration. A possible explanation of the difference between the observed and the expected stochastic energy loss distributions presented by the CCFR group is discussed.PACS number(s): 95.85.Ry, 13.10.+q, 95.55.Vj

Measurement of the energy spectrum of underground muons at Gran Sasso with a transition radiation detector

“…The measured spectrum was consistent with a surface muon differential distribution of the type E −3.71 folded with absorption in 5000 hg/cm 2 standard rock. More recently, a measurement of the cascade showers produced by underground muons inside the NU-SEX calorimeter [3,4] was used to obtain an average muon energy of 346 ± 14 ± 17 GeV at a depth of 5000 hg/cm 2 . The residual energy spectrum was reported to be "not in contradiction with a power law integral distribution with an index γ = 2.712.9".…”