The control system for the ATLAS pixel detector

A pixel detector is under construction for A Toroidal LHC ApparatuS (ATLAS) experiment, which will utilize the large hadron collider (LHC) at Conseil Europe/spl acute/enne pour la Recherche Nucle/spl acute/aire (CERN). Due to the large number of channels, a data-intensive control system will be required. The choice and design of the requisite hardware for this control system is mainly driven by a high power density and a harsh radiation environment. This includes the development of an interlock system to ensure the safety of the detector, and a special control and supply system for the operation of the optical link connection to the data acquisition (DAQ) readout chain. Given the complexity of the required assembly, a commercial supervisory control and data acquisition (SCADA) system is used. Based on this, we have developed a geographical approach, which matches the different hardware components for the operation of one detector part to uniform software elements. Its tree structure allows clear control of a large amount of information. For the final design, where several SCADA systems are linked, a distributed system is necessary. We have shown this system to work efficiently and will discuss first experiences.