Speaker
Description
The online event selection in ATLAS takes place in two stages. At the first level trigger (Level-1), hardware-based, custom electronics and information from the calorimeters and muon spectrometer are used to select events. At the second and final stage, the High Level Trigger (HLT), software-based, various object-specific algorithms as required by different analysis groups apply further selections to filter events. The HLT algorithms, represented as “trigger chains” are collectively known as the “trigger menu”. Therefore, the ATLAS trigger menu encapsulates the selections used by all ATLAS physics analyses and detector studies. This talk covers the trigger menu and its performance in the first year of Run 3 operations. During the second long shut down of the LHC (LS2, 2019-2021), various upgrades were made to the ATLAS trigger system, including new triggers to optimize the data collection. These upgrades have either been deployed in 2022 or have been tested to be implemented for data taking in 2023. The upgraded trigger system will be able to cope with the much higher levels of pileup expected in Run 3, which reached an average number of interactions per bunch crossing of 40.9 in 2022.
| Which session do you think it fits best? | Run-3 trigger performance |
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