The design and performance of the ATLAS Inner Detector trigger for Run 2

Abstract

The design and performance of the ATLAS Inner Detector trigger algorithms running online on the High Level Trigger processor farm with the early LHC Run 2 data are discussed. The redesign of the ID trigger, which took place during the 2013-15 long shutdown, in order to satisfy the demands of the higher energy LHC Run 2 operation is described. The Inner Detector High Level Trigger algorithms are essential for nearly all trigger signatures within the ATLAS trigger. The performance of the tracking algorithms with the early Run 2 data for the different trigger signatures is presented, including the detailed timing performance for the algorithms running on the redesigned single stage ATLAS HLT Farm. A comparison with the Run 1 strategy is made and demonstrates the superior performance of the strategy adopted for Run 2.