Energy reconstruction of the ATLAS Tile Calorimeter under high pile-up conditions using the Wiener filter

The ATLAS experiment records data from the proton-proton collisions produced by the Large Hadron Collider (LHC). The Tile Calorimeter is the hadronic sampling calorimeter of ATLAS in the region |$\eta$| < 1.7. It uses iron absorbers and scintillators as active material. Jointly with the other calorimeters it is designed for reconstruction of hadrons, jets, $\tau$-lepton and missing transverse energy. It also assists in muon identification. The energy deposited by the particles in the Tile Calorimeter is read out by approximately 10,000 channels. The signal provided by the readout electronics for each channel is digitized at 40 MHz and its amplitude is estimated by an optimal filtering algorithm. The increase of LHC luminosity leads to signal pile-up that deforms the signal of interest and compromises the amplitude estimation performance. This work presents the proposed algorithm, based on the Wiener filter theory, for energy estimation in the Tile Calorimeter under high pile-up conditions during LHC Run 3. The performance of the proposed method is studied under various pile-up conditions and compared with the current optimal filtering method using proton-proton collision data.