MULTIPLE INTERACTIONS OF MUONS IN THE NUSEX DETECTOR AND MUON ENERGY-SPECTRUM DEEP UNDERGROUND

Multiple electromagnetic interactions of high energy cosmic ray muons in the NUSEX detector (5000 mwe underground) have been analysed. Diffe rent modes of the pair meter technique have been used to investigate t he muon energy spectrum shape at the observation depth. The observed e vent distributions are in good agreement with the expectation based on the usual picture of underground muon spectra. The first experimental estimates of the muon spectrum parameters at great depths have been o btained. A comparison of the estimated average muon energy with the av ailable theoretical calculations is given.