Detection of muon bundles from cosmic ray showers at medium depth underground

The DELPHI detector at Large Electron-Positron collider (LEP) at CERN near Geneva, has been used to detect multimuon bundles originated from cosmic ray interactions in the atmosphere. The muon multiplicity distribution has been measured over a wide range of multiplicities. The cosmic events registered during the years 1999 and 2000 correspond roughly to 1.6 10/sup 6/ s of effective run time. This paper provides a preliminary comparison between the data and a prediction of the QGSJET model implemented to the CORSIKA simulation package. (6 refs).