V. Grassi

The Atlas liquid argon calorimeter at the CERN Large Hadron Collider: General performance and latest developments of the High Voltage system

The ATLAS experiment is designed to study the proton-proton collisions produced at the Large Hadron Collider (LHC) at CERN. Liquid argon sampling calorimeters are used for the identification and characteristics measurement of the electrons, photons and hadronic jets. Since the first collisions in 2010, the calorimeters operated almost optimally, playing a leading role in the discovery of the Higgs boson announced in July 2012. A special emphasis in this paper will be given on the latest developments of the high voltage power supply system. These efforts allowed to equip the calorimeters with innovative power supply modules able to temporarily sustain high current load without major voltage drop.

The ATLAS Detector Control System

The ATLAS experiment is one of the multi-purpose experiments at the Large Hadron Collider (LHC) at CERN, constructed to study elementary particle interactions in collisions of high-energy proton beams. Twelve different sub detectors as well as the common experimental infrastructure are controlled and monitored by the Detector Control System (DCS) using a highly distributed system of 140 server machines running the industrial SCADA product PVSS. Higher level control system layers allow for automatic control procedures, efficient error recognition and handling, manage the communication with external systems such as the LHC controls, and provide a synchronization mechanism with the ATLAS data acquisition system. Different databases are used to store the online parameters of the experiment, replicate a subset used for physics reconstruction, and store the configuration parameters of the systems. This contribution describes the computing architecture and software tools to handle this complex and highly interconnected control system.