Track finding of cosmic multimuon events in the L3+C muon detector

We describe a track finding method based on the combinatorial Hough transform (CHT) in the large drift chambers of the L3+C experiments at CERN. With the feature of near parallelism of muons in cosmic multimuon events, the dominant direction can be estimated from the histogram of directions of segments. Then the CHT in finding the whole track can be greatly optimized. The cross octant reconstruction program can efficiently reconstruct cosmic muon events with multiplicity up to 50.