A large area ( 128 m ^ { 2 } ) Muon Tracking Detector ( MTD ) , located within the KASCADE experiment , has been built with the aim to identify muons ( E _ { \mu } > 0.8GeV ) and their directions in extensive air showers by track measurements under more than 18 r.l .
shielding .
The orientation of the muon track with respect to the shower axis is expressed in terms of the radial- and tangential angles .
By means of triangulation the muon production height H _ { \mu } is determined .
By means of H _ { \mu } , a transition from light to heavy cosmic ray primary particle with increasing shower energy E _ { o } from 1-10 PeV is observed .
Muon pseudorapidity distributions for the first interactions above 15km are studied and compared to Monte Carlo simulations .