Analysis of Multi Muon Events in the L3 Detector

The muon density distribution in air showers initiated by osmi parti les is sensitive to the hemi al omposition of osmi rays. The density an be measured via the multipli ity distribution in a nite size dete tor, as it is L3. With a shallow depth of 30 meters under ground, the dete tor provides an ex ellent fa ility to measure a high muon rate, but being shielded from the hadroni and ele troni shower omponent. Subje t of this thesis is the des ription of the L3 Cosmi s experiment (L3+C), whi h is taking data sin e May 1999 and the analysis of muon bundles in the large magneti spe trometer of L3. The new osmi trigger and readout system is brie y des ribed. The in uen e of dierent primaries on the multipli ity distribution has been investigated using Monte Carlo event samples, generated with the CORSIKA program. The simulation results showed that L3+C measures in the region of the \knee" of the primary spe trum of osmi rays. A new pattern re ognition has been developed and added to the re onstru tion ode, whi h enables the program, to re ognise events having a high number of tra ks. A omparison of the data with a simple two- omponent-model, whi h des ribes the hemi al omposition of the primary osmi radiation with protons and iron nu lei, shows good agreement within the statisti al error.