The ATLAS liquid argon calorimeter read-out system

The liquid argon calorimeters play a central role in the ATLAS experiment. The environment at the LHC collider imposes challenging tasks to their read-out system. To achieve measurements of particles and trigger signals at high precision, the detector signals are processed at various stages before reaching the data acquisition system (DAQ). Signals from the calorimeter cells are received by front-end boards, which digitize and sample the incoming pulse. Readout driver (ROD) boards further process the data at a trigger rate of up to 75 kHz. An optimal filtering procedure is applied to optimize the signal-to-noise ratio. The ROD boards calculate precise energy, time and quality of the detector pulse, which are then sent to the DAQ. In addition, the RODs perform a monitoring of the data. The architecture of the ATLAS liquid argon detector read-out is discussed, in particular the design and functionality of the ROD board. Performance results obtained with ROD prototypes as well as experience from complete test setups with final production boards are reported.