Efficiency and accuracy of time-of-flight detector measurements in the ATLAS experiment and di-photon vertex reconstruction for the search for an axion-like particle in data from LHC Run-3

In summer 2022, the first LHC Run-3 proton-proton collision data were recorded with the ATLAS central detector and the ATLAS Forward Proton (AFP) detectors. An analysis of this data was performed. Two methods were used to study the efficiency of the Time-of-Flight (ToF) detector for all 2022 data. For the determination of the ToF time resolution, first an elaborate calibration was performed. These performance studies of the ToF data included a proton-proton vertex reconstruction using the matching of ToF and central ATLAS vertex positions. After a calibration of time delays, a preliminary resolution of the vertex reconstruction was determined with a low-𝜇 ATLAS data set. In addition, based on selected di-photon events, a vertex reconstruction study was conducted with a high-𝜇 2022 data set. The potential of ToF data for an improved vertex reconstruction and thus reduction of background in an Axion-Like-Particle search using AFP data has been demonstrated.