Pattern-matching track reconstruction for the BES III main Drift Chamber

The tracking algorithm, MdcPatRec, is developed for the Drift Chamber of the BES III detector using C++ language and object-oriented techniques. This algorithm uses a pattern matching method to find track segments and then combine them into track candidates followed by a least square fit. With the simulation data, the tracking performances such as efficiencies and momentum resolution have been studied and results are consistent with parameters from detector design. The algorithm is also proved to be robust enough to process data with severe background expected by the BES III experiment.