Implementation of an object oriented track reconstruction model into multiple LHC experiments

Abstract

An Object Oriented (OO) model (Gaines et al., 1996; 1997; Gaines and Qian, 1998; 1999) for track reconstruction by the Kalman filtering method has been designed for high energy physics experiments at high luminosity hadron colliders. The model has been coded in the C++ programming language and has been successfully implemented into the OO computing environments of both the CMS (1994) and ATLAS (1994) experiments at the future Large Hadron Collider (LHC) at CERN. We shall report: (1) how the OO model was adapted, with largely the same code, to different scenarios and serves the different reconstruction aims in different experiments (i.e. the level-2 trigger software for ATLAS and the offline software for CMS); (2) how the OO model has been incorporated into different OO environments with a similar integration structure (demonstrating the ease of re-use of OO program); (3) what are the OO model's performance, including execution time, memory usage, track finding efficiency and ghost rate, etc.; and (4) additional physics performance based on use of the OO tracking model. We shall also mention the experience and lessons learned from the implementation of the OO model into the general OO software framework of the experiments. In summary, our practice shows that the OO technology really makes the software development and the integration issues straightforward and convenient; this may be particularly beneficial for the general non-computer-professional physicists.