An On-Line Acoustic Fluorocarbon Coolant Mixture Analyzer for the ATLAS Silicon Tracker

作者：Bates R^*; Battistin M; Berry S; Bitadze A; Bonneau P; Bousson N; Boyd G; Botelho Direito J; DiGirolamo B; Doubek M; Egorov K; Godlewski J; Hallewell G; Katunin S; Mathieu M; McMahon S; Nagai K; Perez Rodriguez E; Rozanov A; Vacek V; Vitek M

来源：IEEE Transactions on Nuclear Science, 2012, 59(5): 2367-2374.

DOI：10.1109/TNS.2012.2209895

• Evaporative cooling
• fluorocarbons
• gas composition detector
• signal processing
• speed of sound measurements
• thermodynamics
• ultrasonic transducers

The ATLAS silicon tracker community foresees an upgrade from the present octafluoropropane (C3F8) evaporative cooling fluid to a composite fluid with a probable 10-20% admixture of hexafluoroethane (C2F6). Such a fluid will allow a lower evaporation temperature and will afford the tracker silicon substrates a better safety margin against leakage current-induced thermal runaway caused by cumulative radiation damage as the luminosity profile at the CERN Large Hadron Collider increases. Central to the use of this new fluid is a new custom-developed speed-of-sound instrument for continuous real-time measurement of the C3F8/C2F6 mixture ratio and flow. An acoustic vapour mixture analyzer/flow meter with new custom electronics allowing ultrasonic frequency transmission through gas mixtures has been developed for this application. Synchronous with the emission of an ultrasound %26apos;chirp%26apos; from an acoustic transmitter, a fast readout clock (40 MHz) is started. The clock is stopped on receipt of an above threshold sound pulse at the receiver. Sound is alternately transmitted parallel and anti-parallel with the vapour flow for volume flow measurement from transducers that can serve as acoustic transmitters or receivers. In the development version, continuous real-time measurement of C3F8/C2F6 flow and calculation of the mixture ratio is performed within a graphical user interface developed in PVSS-II, the Supervisory, Control and Data Acquisition standard chosen for LHC and its experiments at CERN. The described instrument has numerous potential applications-including refrigerant leak detection, the analysis of hydrocarbons, vapour mixtures for semi-conductor manufacture and anesthetic gas mixtures.

• 出版日期2012-10