Commissioning of the calorimetry in the ATLAS tau trigger system

Abstract

Calorimeters are fundamental in the three levels of the ATLAS tau trigger system. The first level trigger uses the electromagnetic and hadronic calorimeters to make its decision. In the High Level Triggers, these systems are also crucial: both the second level trigger and the third level trigger (Event Filter) heavily exploit the calorimeter based information to identify tau leptons decaying hadronically. While the granularity of the first level is coarse, the second and third level triggers have the full detector read-out. This contribution focuses on the commissioning of the calorimetry in the three levels of the tau trigger with real data. Efficiency measurements with respect to tau candidates reconstructed by the offline algorithms, and distributions of calorimeter based tau information reconstructed at trigger level, are compared to the prediction of the Monte Carlo simulation and the trigger performance with first data is assessed.