THE ATLAS UPGRADE PROGRAM

In 2018 he ATLAS detector started the preparations for an ambitious physics project, aiming at the exploration of very rare processes and extreme phase spaces, an endeavor that will require a substantial increase in the amount of data to be taken. To accomplish this purpose, a comprehensive upgrade of the detector and associated systems was devised and planned to be carried out in two phases. The Phase-I upgrade program, completed in 2021, includes new features for the muon detector, for the electromagnetic calorimeter trigger system, and for all trigger and data acquisition chain. For the heavy-ion program, a new Zero Degree Calorimeter (ZDC) with improved radiation hardness will be installed. Upon reaching an integrated luminosity of 350 fb(-1), the LHC will undergo a new upgrade, becoming the High-Luminosity LHC (HL-LHC).