The ATLAS Jet Trigger at 13 TeV

he new Large Hadron Collider (LHC) center of mass energy and expected high luminosity conditions impose more demanding constraints on the ATLAS online trigger than ever before. The immense rate of proton-proton collisions must be reduced from the bunch-crossing rate of 40 MHz to approximately 1 kHz before the data can be written on disk for offline analysis. The ATLAS Trigger System performs real-time reconstruction and selection of these events in order to achieve this reduction. The selection of events containing jets is uniquely challenging at a hadron collider where nearly every event contains significant hadronic activity. It is, however, of crucial importance for several physics analyses, including early searches for new physics in the new kinematic regime. Following the very successful first LHC run in 2010/12, the ATLAS Trigger was much improved, including a new hardware topological module and a restructured High Level Trigger system, merging two previous software-based processing levels. After summarizing the overall performance of the jet trigger during the first LHC run, the software design choices and use of the topological module will be reviewed. The expected performance of jet trigger for the second LHC run will be described and compared with the first trigger results from real data.