Measurement of cosmic ray muon flux in the Belgrade ground level and underground laboratories

The cosmic-ray muon count rate and energy loss spectra in plastic scintillator detectors are recorded in the Institute of Physics, Belgrade. Measurements are performed at two different levels: at the surface level (78 m a.s.l.) and in the Belgrade underground laboratory at the depth of 25 m.w.e. From experimental data and with the use of GEANT4 computer simulation the flux and vertical intensities have been determined. At ground level the muon flux is determined to be J1G=(1.37±0.06)×10-2s-1cm-2 and vertical intensity IvG=(8.4±0.4)×10-3s-1cm-2sr-1 while the same quantities underground are J1U=(4.5±0.2)×10-3s-1cm-2 and IvU=(2.5±0.2)×10-3s-1cm-2sr-1. Their relation to the results of similar measurements worldwide is discussed.