The Tile Calorimeter (TileCal) is the hadronic calorimeter covering the central region of the ATLAS detector
at the LHC. It is a sampling calorimeter consisting of alternating thin steel plates and scintillating tiles.
Wavelength shifting fibers coupled to the tiles collect the produced light and are read out by photomultiplier
tubes. An analog sum of the processed signal of several photomultipliers serves as input to the first level of
trigger. Photomultiplier signals are then digitized and stored on detector and are only transferred off
detector once the first trigger acceptance has been confirmed.
The Large Hadron Collider (LHC) has envisaged a
series of upgrades towards a High Luminosity LHC (HL-LHC) delivering five times the LHC nominal instantaneous
luminosity. The ATLAS Phase II upgrade, in 2024, will accommodate the detector and data acquisition system for
the HL-LHC. In particular, TileCal will undergo a major replacement of its on- and off-detector electronics.
All signals will be digitized and then transferred directly to the off-detector electronics, where the signals
will be reconstructed, stored, and sent to the first level of trigger at a rate of 40 MHz. This will provide
better precision of the calorimeter signals used by the trigger system and will allow the development of more
complex trigger algorithms. Changes to the electronics will also contribute to the reliability and redundancy
of the system.
Three different frontend options are presently being investigated for the upgrade and a final
solution will be chosen after extensive laboratory and test beam studies that are in progress. A hybrid
demonstrator module is being developed using the new electronics while conserving compatibility with the
current system. The demonstrator is undergoing extensive testing and is planned for insertion in ATLAS during
the next possible opening at the end of 2016.