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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 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
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
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
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
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
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
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
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
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
Schematic of Cosmic ray muon trigger XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004
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
Schematic of data acquisition system XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004
Data acquisition system electronics CAMAC NIM XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004
V-I characteristics Small RPC Large RPC XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004
Typical RPC pulse profile RPC pulse Muon trigger XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004
Noise rate and efficiencies XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004
Charge performance XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004
Timing performance XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004
Charge-time linearity XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004
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
Controlled humidity test Carlo Gustavino et al, LNGS XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004
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
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
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
Backup slides XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004
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
Telescope stability monitoring XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004
Preliminary cross-talk measurements XVI DAE-BRNS High Energy Physics symposium, SINP, Kolkata, Nov 29 - Dec 3, 2004
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