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.