The ATLAS Trigger in 2017 and 2018 - developments and performance

This presentation gives a comprehensive review of the ATLAS trigger system in 2017, covering briefly the changes compared to 2016, operational aspects, and encountered constraints. The trigger menu strategy for 2018, the last year of Run-2 will be shown. Focus will be put on the new event-topology-based selections at the Level-1 trigger, and on the trigger performance at high pile-up seen in 2017. The improvement measures taken for 2018 will be discussed and substantiated with first 2018 trigger performance plots