The detector control system of the ATLAS experiment

The ATLAS experiment is one of the experiments at the Large Hadron Collider, constructed to study elementary particle interactions in collisions of high-energy proton beams. The individual detector components as well as the common experimental infrastructure are supervised by the Detector Control System (DCS). The DCS enables equipment supervision using operator commands, reads, processes and archives the operational parameters of the detector, allows for error recognition and handling, manages the communication with external control systems, and provides a synchronization mechanism with the physics data acquisition system. Given the enormous size and complexity of ATLAS, special emphasis was put on the use of standardized hardware and software components enabling efficient development and long-term maintainability of the DCS over the lifetime of the experiment. Currently, the DCS is being used successfully during the experiment commissioning phase

The Common Infrastructure Control of the ATLAS experiment

ATLAS is one of the experiments at the Large Hadron Collider (LHC), constructed to study proton-proton collisions at the unprecedented energy of 14 TeV. In order to guarantee efficient and safe operation of the ATLAS detector, an advanced Detector Control System (DCS) has been implemented. With more than 150 PCs, the DCS is a highly distributed system, hierarchically organized for operating the detector. An important role is played by the Common Infrastructure Control (CIC), supervising the experimental area. The CIC provides monitoring and control for all common services and for the environment in the cavern and in the counting rooms. Distributed I/O concentrators, called Embedded Local Monitor Boards (ELMB), have been developed to operate under the special conditions of the experiment such as strong magnetic field and ionizing radiation. They are used for a variety of applications and are geographically distributed over the whole experiment. The communication is handled via the Controller Area Network (CAN) fieldbus using the CANopen protocol. Information and high level control is available to the users by a Finite State Machine (FSM) software running in the control room and information is also displayed on the web. The technical infrastructure of ATLAS has continuously been supervised during the commissioning phase by the CIC and ensures safe operation

Hierarchical control for the ATLAS experiment

The ATLAS experiment is composed of a set of sub-detectors which have differing requirements for operation. The task of the Detector Control System is to enable the coherent and safe operation of the experiment. In order to provide the required functionality, the Back-End of the control system is hierarchically organized, using a Finite State Machine approach. This paper presents the overall architecture and the standardized interfaces used to represent the sub-detectors, sub-systems and hardware components that constitute the hierarchical experiment control system

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