A parameterization of the Kalman filter track reconstruction in the ALICE TPC

The complete simulation of the ALICE Time Projection Chamber is very demanding in terms of CPU time and disk space. Therefore, a fast simulation is necessary for the study of physics signals requiring a very large number of events. We have implemented and tested a parameterization of the Kalman filter tracking in the TPC to describe the tracking efficiency, the resolution on track parameters, the covariance matrix and the dE/dx. The different particle species are treated separately. As an example, we used this tool to perform the tracking in the ITS using the Kalman filter without including the TPC in the simulation. The reduction in CPU time and disk space is of a factor 35.