A. Polini

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.

Study of the performances of the level-1 trigger system for muons in the barrel of ATLAS with cosmic rays

The muon trigger in ATLAS is crucial for all the main physics channels to be studied at the design center of mass energy and luminosity of LHC and also for the initial phase of data taking with beams for the calibration of all the detectors. The level-1 trigger system for muons in ATLAS is performed using dedicated RPC chambers in the |η| ≪ 1 region. The trigger electronics provides both trigger and readout information. This system is being commissioned using cosmic rays with the full trigger and data acquisition chains. Monitoring tools have been developed in order to spot problems during data taking and determine the quality of the data and the trigger performance. Moreover, using the data taken during the commissioning phase, with partial availability of the detector, some studies have been performed to allow the optimization of the trigger system, based on different choises of the configuration parameters, also as a function of the detector working point. In this paper we would like to describe the extensive tests performed on the system and illustrate the possible performances with different conditions.