The Detector Control System of the ATLAS experiment at CERN: An application to the calibration of the modules of the Tile Hadron Calorimeter

The principle subject of this thesis work is the design and development of the Detector Control System (DCS) of the ATLAS experiment at CERN. The DCS must ensure the coherent and safe operation of the detector and handle the communication with external systems, like the LHC accelerator and CERN services. A bidirectional data flow between the Data AcQuisition (DAQ) system and the DCS will enable coherent operation of the experiment. The LHC experiments represent new challenges for the design of the control system. The extremely high complexity of the project forces the design of different components of the detector and related systems to be performed well ahead to their use. The long lifetime of the LHC experiments imposes the use of evolving technologies and modular design. The overall dimensions of the detector and the high number of I/O channels call for a control system with processing power distributed all over the facilities of the experiment while keeping a low cost. The environmental conditions require the utilization of magnetic field and radiation tolerant equipment. Homogeneity throughout the system, despite of the diversity of equipment and the number of people involved, is a key concern in the design of the DCS. For these reasons, the DCS will be implemented using well defined building blocks to reduce the design work, to ease commissioning and integration and to minimize the maintenance effort required during the lifetime of the experiment. This thesis is divided into two main parts. In the first one, the requirements of the DCS are analyzed and the overall architecture of the system is designed. The building blocks of the system, and the different tests performed for their qualification for operation in ATLAS are presented. In the second part, the different technologies of the DCS are used to implement the control system for the final calibration of the modules of the ATLAS Tile Hadron Calorimeter. In addition, the effect of the DCS controlled parameters on the calorimeter response (e.g. the energy resolution and the linearity of the response) have been studied.