Electronic readout of the ATLAS Liquid Argon calorimeter: Calibration and performance

The Liquid Argon (LAr) calorimeter is a key detector component in the ATLAS experiment at the Large Hadron Collider (LHC) at CERN. The LAr calorimeter is designed to provide precision measurements of electrons, photons, jets and missing transverse energy. It consists of a set of sampling calorimeters kept in three separate cryostats with liquid argon as the active medium. The electronic readout of the ATLAS LAr calorimeters is divided into a Front End (FE) system of boards mounted in custom crates directly on the cryostat feedthroughs, and a Back End (BE) system of VME-based boards located in an off-detector underground counting room where there is no radiation. After a brief overview of the LAr readout electronics, we present a description of the methods used to reconstruct the calorimeter pulses and the system performance. Given the intrinsic limitations imposed by the current FEBs, an upgrade will be necessary to maintain ATLAS physics potential at luminosities beyond 10³⁴ cm^-2 s^-1. We also present a brief description of the ongoing upgrade efforts.