Radiation Tolerant Electronics and Digital Processing for the Phase-I Trigger Readout Upgrade of the ATLAS Liquid Argon Calorimeters

The high luminosities of $\mathcal{L} > 10^{34} \mathrm{cm}^{-2} \mathrm{s}^{-1}$at the Large Hadron Collider (LHC) at CERN produce an intense radiation environment that the detectors and their electronics must withstand. The ATLAS detector is a multi-purpose apparatus constructed to explore the new particle physics regime opened by the LHC. Of the many decay particles observed by the ATLAS detector, the energy of the created electrons and photons is measured by a sampling calorimeter technique that uses Liquid Argon (LAr) as its active medium. The Front End (FE) electronic readout of the ATLAS LAr calorimeter located on the detector itself consists of a combined analog and digital processing system. The FE electronics were qualified for radiation levels corresponding to 10 years of LHC operations. The high luminosity running of the LHC (HL-LHC), with instantaneous luminosities of $5 \times 10^{34} \mathrm{cm}^ {-2} \mathrm{s}^{-1}$ and an integrated luminosity of $3000 \ \mathrm{fb}^{-1}$ will exceed these design qualifications. In order to exploit the higher luminosity while keeping the same trigger bandwidth of 100 kHz, higher transverse granularity, higher resolution and longitudinal shower shape information will be provided from the LAr calorimeter to the Level-1 trigger processors.