ATLAS-detector operation with beams: the data-acquisition perspective

This year, the Large Hadron Collider at CERN is entering into a continuous operation mode, with the aim of providing proton-proton collisions at the anticipated energy of 7 TeV. In this paper we report on the experience with the ATLAS data-acquisition system during this phase. As a matter of fact, the continuous operation with beam is posing new challenges with respect to the past cosmic data-taking periods. The first LHC collision data will be primarily used to commission the trigger and to understand the detector and physics performance. Therefore, the ATLAS operation will impose new, unforeseen requirements and variable working conditions, like large event sizes and non-standard trigger configurations. The flexibility of both the data-flow system and the trigger infrastructure as well as the capability of monitoring the system operation and the quality of the data will be probed and exploited. In addition, an important goal for the data-acquisition system is the maximization of the data-taking efficiency. Dedicated automatic procedures, including runtime reconfiguration and prompt error handling and recovery, are or will be put in place. These however rely on a correct interaction with both the ATLAS sub-detectors and, for the first time, the LHC. Hence, further developments, aiming at the mastering of these interactions, are expected.