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Results from development of Glass RPCs for INO detector

Results from development of Glass RPCs for INO detector. B.Satyanarayana (For INO Collaboration) TIFR, Mumbai. Plan of the presentation. Introduction Principle of operation of a glass RPC Overview of the field Our prototype designs and fabrication RPC gas mixtures and gas system

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Results from development of Glass RPCs for INO detector

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  1. Results from development ofGlass RPCs for INO detector B.Satyanarayana (For INO Collaboration) TIFR, Mumbai XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  2. Plan of the presentation • Introduction • Principle of operation of a glass RPC • Overview of the field • Our prototype designs and fabrication • RPC gas mixtures and gas system • Cosmic ray muon telescope • Data acquisition system • Preliminary results • RPC aging problem • Future work plan XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  3. Introduction • Neutrinos are one of the fundamental particles of matter. • Electrically neutral and were initially thought to be mass less. • Three types or flavors (ne,nm,nt) of neutrinos known. • Recent evidence indicates that neutrinos have mass and also experience mixing among these flavors. • Neutrino oscillations can explain the discrepancy between theory and observations about its flux; can be used to estimate its mass. • Pioneering experiments at the KGF underground laboratories. • Formation of Indian Neutrino Observatory (INO) collaboration. • Feasibility studies for setting up of a neutrino experiment in India is in progress. XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  4. Proposed INO detector • RPC dimension: 3m X 2m • No of chambers: 11K • No of channels: 220K • No of TDC channels: 3K Magnetised iron calorimeter Iron 140 layers RPC 35KTons XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  5. Principle of operation of a RPC V-I model Each discharge locally deadens the RPC. The recovery time is approximately XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  6. Our prototype designs: Single gap Gas inlet Two versions Graphite coat Spacer Gas outlet HV terminals XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  7. Our prototype designs: Double gap Double gap RPC for better detection efficiencies XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  8. Jigs for RPC fabrication Glass handlers Resistivity measurement jig Glue and dispensers RPC fabrication jig A finished small area RPC A glued RPC XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  9. Gas mixing and flow control unit Flow monitor Gas mixing unit XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  10. Schematic of Cosmic ray muon trigger XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  11. Cosmic ray muon telescope setup Mounting structure for flexible and precise telescope alignment Paddle alignment detail XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  12. Schematic of data acquisition system XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  13. Data acquisition system electronics CAMAC NIM XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  14. V-I characteristics Small RPC Large RPC XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  15. Typical RPC pulse profile RPC pulse Muon trigger XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  16. Noise rate and efficiencies XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  17. Charge performance XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  18. Timing performance XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  19. Charge-time linearity XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  20. RPC aging problem • Drop in efficiency, increase in noise rate and chamber current seen after a few weeks of continuous operation • Reports in the literature (Monolith, Belle etc) • Moister contamination in Freon gas, the culprit? • Use of SF6 instead of Freon preferred XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  21. Controlled humidity test Carlo Gustavino et al, LNGS XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  22. AFM images of damaged electrodes 2 scans 10 scans Raw glass Damaged electrodes Raw glass Damaged electrodes • 500nm structures of 100nm thick seen in the images XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  23. SEM image of damaged electrode 6 scan 2 scan Raw glass Fluorine: 4% Damaged electrode Fluorine: 38% XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  24. Future work plan • Systematic study of RPC stability problem • Fabrication of more large area RPCs and studies • Detailed studies on timing, spatial resolution, cross-talk • Optimization of detector gas composition • INO prototype detector; needs about 16 large area RPCs • Performance studies of prototype detector; comparison of results with those from simulation studies • RPC Parameter inputs for electronics and data acquisition system design • Full pledged RPC device simulations XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  25. Backup slides XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  26. RPCs of modern designs Hybrid RPC Micro RPC Multi gap • Applications in HEP research • Cosmic ray experiments: EAS-Top, Cover-Plastex, Argo, Auger • Accelerator based experiments: Belle, Babar, Star, Harp • Future experiments: Alice, ATLAS, CMS, LHCb • Medical applications etc XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  27. Telescope stability monitoring XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  28. Preliminary cross-talk measurements XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

  29. Recovery of a damaged RPC • Purging with pure Argon at high flow rate. • Bubbling pure Argon through pure ethyl alcohol. • Bubbling pure Argon through 3% Ammonia solution for 24 hours with high voltage off. • Recovers efficiency and brings down noise rate. XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004

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