Design and Performance of an Object Oriented Model for CMS Track Reconstruction

An Object Oriented ( OO) model for the CMS central tracking reconstruction has been designed and coded in the C++ programming language. It has been tested with single and multiple track events and has been compared with non-OO programs. The class design of the model is based on well-known data concepts for track reconstruction in HEP, so it should be rather easily understood and adopted by non-expert class users. Extensive use has been made of the C++ Standard Template Library ( STL) in the class design and program coding. A special feature of this model is that it is closely related to the Kalman filtering track reconstruction package in the current CMS simulation and reconstruction facility ( CMSIM) which is coded in FORTRAN. Many well-optimized FORTRAN subroutines in the package have been successfully re-used as member functions of various classes in the OO model. Hopefully, this mode l can demonstrate a possible means for a smooth transition to future object oriented programs in HEP.