  The MACRO experiment detected more than 300000 multiple muon events. We
analysed these events to measure the distribution of the separation of
underground TeV muons (decoherence function), up to a distance of 70 meters. On
a subsample of very high multiplicity events, we performed two independent
analyses, based on the study of the spatial structure of the bundles. Both the
analyses revealed a correlation between the topology of the bundles and the
dynamics of the shower development in atmosphere. These results have been used
to constrain and disentangle the primary composition and the hadronic
interaction models used by different shower propagation codes
(HEMAS-DPM/CORSIKA).
