The ATLAS transition radiation tracker (TRT) detector control system

The TRT (Transition Radiation Tracker) is one of the ATLAS experiment Inner Detector components providing precise tracking and electrons identification. It consists of about 350000 proportional counters (straws) which have to be filled with stable active gas mixture and high voltage biased. High voltage settings at distinct topological regions are periodically modified by closed-loop regulation mechanism to ensure a constant gaseous gain independent of drifts of atmospheric pressure, local detector temperatures and gas mixture composition. Low voltage system powers front-end electronics. Special algorithms provide fine tuning procedures for detector-wide discrimination threshold equalization to guarantee uniform noise figure for whole detector. Detector, cooling system and electronics temperatures are continuously monitored by about 3000 temperature sensors. The standard industrial and custom developed server applications and protocols are used for devices integration into unique system. All parameters originating in TRT devices and external infrastructure systems (important for Detector operation or safety) are monitored and used by alert and interlock mechanisms. System runs on 11 computers as PVSS (industrial SCADA) projects and is fully integrated with the ATLAS detector control system. (authors)