A Probabilistic Data Association Filter for fast tracking in the ATLAS Transition Radiation Tracker

The ATLAS Level 2 Trigger algorithm for simultaneous pattern recognition and track fitting in the ATLAS Transition Radiation Tracker (TRT) is presented. The algorithm employs the Probabilistic Data Association Filter (PDAF) as a tool for “hit-to-track” association and track parameter estimation. An introduction to the PDAF technique and details of its implementation for tracking and electron identification in the TRT are given. The results of tests on simulated data with high track multiplicity are presented and discussed.