Operation of the ATLAS Experiment: Organization of the Detector Controls and the Data Acquisition System

The overall control of the ATLAS experiment includes the supervision of the hardware in the experimental set-up and the common experimental infrastructure, as well as the supervision of all processes involved in the event readout. This functionality is provided by two independent, although complementary and interacting systems: control for trigger and data acquisition (TDAQ), and the detector control system (DCS). The size and complexity of both systems suggest a hierarchical structure as the natural way to organize the control of the detector. The hierarchical control of both systems is driven by two independent finite state machines. This paper mainly discusses the hierarchical control of ATLAS, how the use of FSMs is approached, and the coordination between the two systems to ensure a coherent operation. In addition, the interfaces to DCS and TDAQ that will be used in the future ATLAS control room are shown