Upgraded readout electronics for the ATLAS LAr calorimeter at the phase I of LHC

The ATLAS Liquid Argon (LAr) calorimeters produce a total of 182,486 signals which are digitized and processed by the front-end and back-end electronics at every triggered event. In addition, the front-end electronics is summing analog signals to provide coarsely grained energy sums, called trigger towers, to the first-level trigger system, which is optimized for nominal LHC luminosities. However, the pile-up noise expected during the high luminosity phases of LHC will be increased by factors of 3–7. An improved spatial granularity of the trigger primitives is therefore proposed in order to improve the identification performance for trigger signatures, like electrons or photons, at high background rejection rates. The general concept of the upgraded LAr calorimeter readout together with the various electronics components to be developed for such a complex system is presented. The R&D activities and architectural studies undertaken by the ATLAS LAr Calorimeter group are described.