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T: Fachverband Teilchenphysik

T 79: Invited Topical Talks 5

T 79.2: Eingeladener Vortrag

Donnerstag, 7. März 2024, 14:30–15:00, Geb. 30.21: Gerthsen-HS

Hadronic signals at the LHC: timing as a handle to face the challenges of higher luminosity — •Margherita Spalla — Max-Planck-Institut für Physik, München

The physics programme at the Large Hadron Collider (LHC) relies on measuring increasingly rare processes with high precision, while coping with the busier environment driven by increased luminosity. An efficient signal reconstruction is the first step towards this goal. During the LHC Run 1 and 2, the ATLAS experiment has mostly relied on measured energy and momentum, as well as fine detector segmentation. Even though this method has proven highly performant, it is sensitive to the piling-up effect of hadrons from additional soft collisions (pile-up). Integrating a precise measurement of signal timing into the existing reconstruction is gaining interest as a way to improve pile-up suppression. While a dedicated High-Granularity Timing Detector is expected to provide timing information for tracking at the High-Luminosity LHC, a measurement of signal timing is already provided in the current detector by the ATLAS calorimeters. Calorimeter signals are reconstructed based on energy signal-to-noise ratio, they provide the basis for the reconstruction of jets, electrons, photons and τ-leptons. The introduction of a timing criterion in the topological clustering algorithm is shown to suppress pile-up originated jets by ∼50% or more, with no reduction in signal reconstruction efficiency. Such large pile-up suppression also reduces the average ATLAS event size by 6%, improving resource consumption. This method has been adopted as the Run 3 default.

Keywords: timing; ATLAS; signal reconstruction