Expanding the ATLAS discovery potential

by Adriana Milic (CERN)

Wednesday 12 Feb 2025, 13:30 → 14:30 Europe/London

Small Lecture Theatre (Poynting)

The Phase-I upgrade of the ATLAS Liquid Argon and L1Calo trigger system introduces up to ten times finer segmentation at the first trigger level, enabling precise determination of particle production points in the calorimeter. This enhancement is critical for reconstructing long-lived particles, which may not decay immediately at the interaction point, and for complex physics signatures requiring refined particle reconstruction. Additionally, the nanosecond-level timing precision of the LAr calorimeter provides opportunities for delayed triggers, expanding sensitivity to long-lived particle parameter spaces.

To improve detection efficiency for delayed signals, several optimization schemes are proposed. Addressing challenges in capturing small energy deposits, a super cell summing scheme can be implemented to enhance sensitivity to these signals. Such improvements would have a significant impact on searches for new physics, such as long-lived dark photons predicted in Hidden Abelian Higgs Models.

These upgrades, achievable within one year, would benefit Run 3 data-taking. Future developments include leveraging pointing information from the calorimeter to further improve triggering efficiency, aligning with plans for Phase-II system upgrades.