CONFIG. 1: 12mm (Drift) / 12 mm (T1) / 12 mm (T2) / 12 mm (Induction)

1. Characterization of Micro-Pattern Gas Detectors for Application in the CMS Muon Detection System Ions I+ e- 40 % Induction gap e- 60 % Electrons η= 2.4 Staged Drift 3.00 mm Drift gap GEM3 1.00 /2.00 mm T1 GEM2 2.00 mm T2 GEM1 1.00 /2.00 mm Induction gap Anode Drift 3.25 mm Drift gap GEM3 2.215 mm T1 GEM2 2.215 mm T2 GEM1 2.15 mm Induction gap Anode ANALOG AND ASYNCHRONOUS DIGITAL AND SYNCHRONOUS Tracker GEM 2 Tracker GEM 1 Tracker GEM 3 Beamdirection Standard GEM Single-Mask / Honeycomb GEM D. Abbaneo1, S. Bally1, H. Postema1, A. Conde Garcia1, J.-P. Chatelain1, G. Faber1, L. Ropelewski1, E. David1, S. Duarte Pinto1, G. Croci1, M. Alfonsi1, M. van Stenis1, A. Sharma1, S. Bianco2, S. Colafranceschi2, L. Benussi2, F. Fabbri2, G. Saviano2, N. Turini3, E. Oliveri3, G. Magazzu3, A. Marinov4, M. Tytgat4*, N. Zaganidis4, M. Hohlmann5, K. Gnanvo5, Y. Ban6, H. Teng6, J. Cai6 1 CERN, Geneva, Switzerland 2 LNF Frascati, Frascati, Italy 3 Universita' Degli Studi di Siena - INFN Sezione di Pisa, Pisa, Italy 4 Dept. of Physics and Astronomy, University of Gent, Gent, Belgium 5 Dept. of Physics and Space Sciences, Florida Institute of Technology, Melbourne, Florida, USA 6 Peking University, Beijing, China * Michael.Tytgat@cern.ch, presenter of this contribution CMS Endcap Resistive Plate Chamber Muon System Use Micro-Pattern Gas Detectors for CMS Muon Endcap System ? Micro Pattern Gas Detectors : • Spatial resolution ~ 100 m (track< 45°) • Time resolution ~ 4-5 ns • Efficiency > 98% • Rate capability ~104/mm2 • Non-flammable mixtures (like Ar-CO2) • Good gain stability for high particle fluxes • No ageing effects seen for high doses • Improve contribution to CMS Muon Trigger Efficiency  • Combine triggering and tracking functions ? • Instrument the vacant (RE1-4/1) zones in forward CMS endcap region, 1.6 < |η |<2.4 • Enhance and optimize the readout (η-φ) granularity by improved rate capability Endcap chambers are double-gap Bakelite RPCs with strip readout, operating in avalanche mode at 9.5kV with a C2H2F4-iC4H10-SF6 (96.2-3.5-0.3) gas mixture GEM Multi-GEM Micromegas • At present RPC endcap system limited to |η|<1.6 • RPC Endcap completion phase 1, RE4/2-3, in 2012 • Need other technology for RE1-4/1 region to sustain high LHC/SLHC rates of several kHz/cm2! 10x10 cm2 Triple-GEM Prototypes CONFIG. 1: 12mm(Drift) / 12mm(T1) / 12mm(T2) / 12mm(Induction)  Honeycomb triple-GEM Standard double-mask triple-GEM Single-mask triple-GEM Small prototypes were produced and tested at CERN in EN-ICE surface treatment workshop and RD51 lab : • Triple-GEM detectors with 10x10cm2 active area • GEM and cathode foils glued on fiberglass frames and mounted inside gas-tight box • Double/single mask GEMs • Different gap configuration for double mask GEM • Use of honeycomb spacers • Gain and discharge probability measurements Use of single-mask technique to avoid alignment problems during etching of holes in top/bottom of GEM foils Use of honeycomb spacer frames in gaps could avoid the need for GEM foil stretching Different honeycomb structures (drift/T1/T2/induction) : Config 1 : 12 / 12/ 12/ 12mm Config 2 : 6 / 12 / 12 / 12 mm Config 3 : 6 / 0 / 0 / 0 mm • 2 gap size configurations : 3/2/2/2 & 3/1/2/1 mm • Strip pitch = 0.8mm Measurements @ CERN SPS H4 Beamline RD51 triple-GEM beam telescope VFAT readout Prototypes were tested during several RD51 test beam campaigns in the CERN SPS H4 beamline with 150 GeV muons or pions • Gas flow ~5 l/h for different mixtures : Ar-CO2 (70-30, 90-10) Ar-CO2-CF4 (45-15-40, 60-20-20) • VFAT based readout from INFN Siena-Pisa • RD51 triple-GEM beam telescope used for tracking • 3 Standard triple-GEM detectors with 10x10 cm2 active area • Gas mixture Ar-C02 70-30% • Strip pitch = 0.4 mm; 4x128 strips (2X-2Y) • VFAT readout • Always operated at a gain > 104 • VFAT (TOTEM) is a digital on/off chip for tracking and triggering with an adjustable threshold for each of the 128 channels • Trigger function provides programmable “fast OR” information based on the region of the sensor hit • Output signals synchronous with 40MHz (25ns) clock Data Analysis Results Muon and pion beam profile Standard GEM Performance Single-mask GEM Performance Efficiency ~98% VFAT threshold scan Resolution ~270μm compatible with 0.8mm strip pitch Tunable HV divider allowed Drift and Induction field scans • Single-mask GEM reaches similar performance level as standard GEM 4ns time resolution obtained after correction for 25ns VFAT jitter Honeycomb GEM Performance First CMS Size GEM Prototype Clear effect of gain, gas mixture and gap sizes on cluster size • Different prototypes fully operational without major problems • Observed efficiency loss due to honeycomb spacers • Efficiencies : • Config 1 ~ 50% • Config 2 ~ 75% • Config 3 ~ 75% • First full-size triple-GEM prototype for CMS was produced and tested in SPS H4 beamline during October 18-28 RD51 test beam campaign • Single-mask GEM technology • 4x256 readout strips, 35 GEM HV sectors, 4 η partitions • Efficiency plateau at ~98% • Time resolution of 4ns obtained with 3/1/2/1 configuration and Ar-CO2-CF4 (45-15-40) • Very high gain > 104 reachable General conclusions Prototypes demonstrated : • High efficiency and high gain • Good time resolution • Fast electronics • Single-mask GEM technology works well • Honeycomb GEM needs further tuning of efficiency IEEE Nuclear Science Symposium and Medical Imaging Conference, Oct. 30 – Nov. 6, 2010 – Knoxville, Tennessee