The high-energy muon flux at sea level up to 8 TeV derived from the observed burst size spectrum

The size spectrum of bursts produced by high-energy muons in rock has been observed at a depth of 40 m w.e. underground. The apparatus used consisted of two layers of plastic scintillator with 2 cm thickness, having (3.65 × 5.0) m2 area for each layer and being 2.43 m apart vertically. Observed sizes of the bursts were equivalent to a number of traversing relativistic particles from several hundreds to 12 000. From the observed size spectrum, we have estimated the muon energy spectrum at sea level up to 8 TeV considering fluctuations in the number of particles in the developments of their cascade shower. Their integral energy spectrum had a power exponent of 2.5 ± 0.2 in the range from 500 GeV to 8 TeV. The energy spectrum is compared with the spectra observed by other workers and discussed for energy losses of high-energy muons above 1 TeV.