The Phase-II upgrade Demonstrator system for the ATLAS Hadronic Tile Calorimeter facing the High-Luminosity LHC era

The Tile Calorimeter (TileCal) is the central hadronic calorimeter within the ATLAS detector capturing the jet-energy in proton-proton (pp) collisions at the LHC. It is composed of steel absorbers and scintillating tiles, which re-emit part of the absorbed energy in the form of light (Fig. 1). The light from each tile cell is collected by the wavelength shifting fibers and guided to the core element of the detection, the photomultiplier, for converting the incoming photons into an electrical signal. The front-end electronics sums the PMT signals to form a fast analog trigger, digitizes the PMT signals and also integrates the continuous PMT current to measure low-light processes such as gamma rays and minimum bias events. Currently, TileCal records hadrons energies in proton-proton collisions at a centre-of-mass of 14 TeV and a luminosity of 1x1034cm-2s-1[1] with a large dynamic range, being able to identify single muons that deposit about 400 MeV in central cells and also to provide a precise measurements of jet energies up to several TeVs. The High-Luminosity LHC (HL-LHC) is a major upgrade of the Large Hadron Collider aiming to increase the instantaneous luminosity up to 7.5x1034cm-2s-1. This leads to the Phase II Upgrade program for improving the TileCal performances according to the HL-LHC requirements. In order to cope with the increased luminosity, a completely new on-detector and off-detector electronics are being developed, aiming for increased trigger rates and high-performance data acquisition. A hybrid demonstrator prototype module containing a new read-out system was inserted in the ATLAS detector for testing the Phase-II upgrade system during the LS2, as well as for using real conditions of pp collision during the Run-3.