The Detector Control System for ALICE: Architecture and Implementation

<P>Presentation made at LEB99, Snowmass, Colorado, 20-24 September 1999<P>The Alice experiment will include more than 10 individual detectors of different technologies and with specific operating conditions. The instrumentation required to run and control the operation of each sub-detector will include commercial and custom hardware of various standards. <P>The detector control system (DCS) for the ALICE experiment will allow a hierarchical consolidation of the participating systems to obtain a fully integrated detector operation. This goal will be achieved by clearly defined interfaces between system layers. In addition, sub-detectors will continue to be able to access their equipment independently from other sub-detectors for maintenance, upgrading and debugging. The architecture will, therefore, be based on partitioning into self-contained sub-systems, which can be separately developed, maintained and operated. Horizontal communication between sub-systems will consequently be avoided. <P>The DCS will use, where possible, commercial hardware components and software. <P>The clear vertical separation and hierarchical structure of the system should also allow implementing of a single user interface to the experiment, which can access the DAQ control and the DCS.<P>The technologies which will be used for the controller level hardware and the software options are explained. Also described is the current development status and the experience to date with the small-scale prototypes that are used to verify design choices.