Upgrade of the ATLAS Tile Calorimeter for the High Luminosity-LHC

The Tile Calorimeter (TileCal) is a sampling hadronic calorimeter covering the central region of the ATLAS experiment with steel as the absorber and plastic scintillators as the active medium. Scintillators are read out by wavelength shifting fibers coupled to photomultiplier tubes, positioned at the outermost part of the modules. TileCal is used for detecting hadronic particles, discriminating muons, and measuring hadronic particle energy and transverse missing momentum. The upcoming High-Luminosity phase of the LHC, starting in 2030, will increase the nominal instantaneous luminosity by a factor of at least five, alongside an upgraded ATLAS Trigger and Data Acquisition architecture. This upgrade necessitates a complete redesign of the readout electronics and power systems of TileCal. It improves calorimeter signal precision for the trigger system, enabling the development of more effective trigger algorithms. The TileCal upgrade program has involved extensive research and development, including test beam studies and the construction of a Demonstrator module. These proceedings outline recent progress in the development of the onand off-detector systems, expected performance characteristics, and results from test beam campaigns featuring the latest electronics designs.