The high energy muon spectrum in Extensive Air Showers: first data from LVD and EAS-TOP at Gran Sasso

Abstract We present evidence for a dependence of the average deep underground muon energies on shower size in the coincident EAS-TOP and LVD data at the Gran Sasso laboratories. The measured relation agrees with a mixed chemical composition of the cosmic ray primary spectrum at energies around 10 15 eV.