Performance of the ATLAS Calorimeters in LHC Run-1 and Run-2

Abstract

The ATLAS experiment at the Large Hadron Collider (LHC) is equipped with electromagnetic and hadronic liquid-argon (LAr) calorimeters and a hadronic scintillator-steel sampling calorimeter (TileCal) for measuring energy and direction of final state particles in the pseudorapidity range $|\eta|<4.9$. The calibration and performance of the calorimetry system was established through beam tests, cosmic ray muon measurements and in particular the first three years of pp collision data-taking. During this period, referred to as Run-1, approximately 27~\ifb of proton-proton collision data were collected at the center-of-mass energies of 7 and 8~TeV. Following a period of detector consolidation during a long shutdown, Run-2 started in 2015 with approximately 3.9~\ifb of data at a center-of-mass energy of 13~TeV recorded in the first year. We present a summary of the calorimeter operation, monitoring and data quality, as well as their performance, including the calibration and stability of the electromagnetic scale and time resolution. These results demonstrate that the LAr and Tile calorimeters perform excellently within their design requirements. The calorimetry system thus played a crucial role in the Run-1 physics programme, and, in particular, in the discovery of a Higgs boson.