28th Conference on Computing in High Energy and Nuclear Physics (CHEP 2026)

The ATLAS Trigger System

25 May 2026, 13:45

18m

Chulalongkorn University

Oral Presentation Track 2 - Online and real-time computing Track 2 - Online and real-time computing

Speaker

Stefanie Morgenstern (Heidelberg University (DE))

Description

The ATLAS experiment in the LHC Run 3 uses a two-level trigger system to select
events of interest to reduce the 40 MHz bunch crossing rate to a recorded rate
of up to 3 kHz of fully-built physics events. The trigger system is composed of
a hardware based Level-1 trigger and a software based High Level Trigger.
The selection of events by the High Level Trigger is based on a wide variety of
reconstructed objects, including leptons, photons, jets, b-jets, missing
transverse energy, and B-hadrons in order to cover the full range of the ATLAS
physics programme.
We will present an overview of improvements in the reconstruction, calibration,
and performance of the different trigger objects, as well as computational
performance of the High Level Trigger system.