CERN Accelerating science

ATLAS Slides
Report number	ATL-DAQ-SLIDE-2025-443
Title	The Phase-1 Upgrade of the ATLAS level-1 calorimeter trigger
Author(s)	Carroll, Anthony Maurel (University of Oregon (US)) ; ATLAS TDAQ Collaboration
Corporate author(s)	The ATLAS collaboration
Collaboration	ATLAS Collaboration
Submitted to	The 32nd International Symposium on Lepton Photon Interactions at High Energies (Lepton Photon 2025), Madison, Wisconsin, Us, 25 - 29 Aug 2025
Submitted by	acarrol4@uoregon.edu on 04 Sep 2025
Subject category	Particle Physics - Experiment
Accelerator/Facility, Experiment	CERN LHC ; ATLAS
Free keywords	L1Calo ; Phase-I Upgrade ; TDAQ ; Hardware Trigger ; Calorimeter Trigger
Abstract	The ATLAS level-1 calorimeter trigger is a custom-built hardware system that identifies events containing calorimeter-based physics objects, including electrons, photons, taus, jets, and missing transverse energy. In Run 3, L1Calo has been upgraded to process higher granularity input data. The new trigger comprises several FPGA-based feature extractor modules, which process the new digital information from the calorimeters and execute more sophisticated trigger algorithms. The design of the system will be presented along with an analysis of the improved performance of the upgrade in the increasingly challenging Run-3 LHC pile-up environment.