Performance and improvements of the ATLAS Jet trigger system

At the harsh conditions of the LHC, with proton bunches colliding every 50 ns and on average 35 proton-proton interactions per bunch crossing in 2012, the ATLAS trigger system has to be highly flexible to maintain a high and unbiased efficiency for a wide range of physics studies whilst providing a fast rejection of uninteresting events. This is especially important for hadronic jets which are not only the most common final state objects at a hadron collider but also an important signature in many physics analyses. The ATLAS jet trigger system has been supplemented with several new features in 2011, to prepare and improve its performance, especially in multi-jet topologies and for the high pile-up environments present at the increasing LHC luminosities in 2011 and 2012.