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Recent developments of Micromegas detectors for High Energy Physics. ICHEP 2004, Beijing. P. Colas, DAPNIA Saclay. Principle of operation Advantages Experiments in progress Compass, CAST, NA48/Kabes Developments in progress LC-TPC, neutron detection, NOSTOS neutrino experiment,….
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Recent developments of Micromegas detectors for High Energy Physics ICHEP 2004, Beijing P. Colas, DAPNIA Saclay • Principle of operation • Advantages • Experiments in progress • Compass, CAST, NA48/Kabes • Developments in progress • LC-TPC, neutron detection, NOSTOS neutrino experiment,… P. Colas - Micromegas for HEP
Micromegas: Principle of operation Micromegas : a micromesh sustained by 50-100 mm - high insulating pillars. The multiplication takes place between the anode and the mesh Small size -> Fast signals -> Short recovery time -> High rate capabilities 200 mm P. Colas - Micromegas for HEP
S1 S2 Micromegas further advantages S1/S2 ~ Eamplif / Edrift Can choose the gap/HV to have the gain maximum w.r.t. the gap and pressure -> excellent energy resolution Ion feedback suppressed by Edrift/Eamplif P. Colas - Micromegas for HEP
COMPASS • MIP detection for measuring the nucleon spin structure • High particle flow : 105 kHz/cm2 • Sparks give less than 1 per mil dead time • Space resolution < 70 mm with 350 mm strips • The largest Micromegas so far (40x40 cm2) • In operation at CERN since 2002 efficiency>97% P. Colas - Micromegas for HEP
axions Transverse magnetic field (B) L X ray X ray detector CAST CERN Axion Solar Telescope • Solar Axion detection : con- version of solar axions in a LHC magnet -> observe low-energy X-rays • 2D with overlayed crossed strips • In operation at CERN since 2003 P. Colas - Micromegas for HEP
Low energy spectrum from Micromegas in CAST Cu Fe Cu escape Ar Fe escape 6.5 keV g y X CAST • Low threshold : 600 eV ! • Low background (fluorescence) P. Colas - Micromegas for HEP
Tdrift2 Micromegas Gap 50 μm Micromegas Gap 50 μm Tdrift1 NA48/KABES KAon BEam Spectrometer • CP violation • In operation at CERN since summer 2003 • Principle : TPC + micromegas P. Colas - Micromegas for HEP
Space resolution from drift time measurement:70 μm Time resolution: 0.6 ns Using TOT to correct time slewing Tagged K track (T0)KABES- (T0)DCH Spectrometer(ns) Tagging with reconstructed K± ±+ - XStation1 or 2- XStation3(cm) NA48/KABES • Excellent time resolution P. Colas - Micromegas for HEP
electrons chamber ions ions TPC for the Linear Collider Challenging requirements: High two-track separation in jets both in Z and in Rf (O(8mm)) High background from photons and neutrons (600 n/BX) Excellent jet resolution (E-flow) Particle identification High granularity, small diffusion High granularity Low ion feedback Low H-content of the gas Low material budget of the endplate (thin frame) Good dE/dx resolution => Micropattern detectors P. Colas - Micromegas for HEP
1024 pads Berkeley-Orsay-Saclay TPC Pad layout Field cage Detector Readout P. Colas - Micromegas for HEP
LC-TPC FUTURE PROJECTS, R&D Cosmic ray data taking in May 2004. Accurate measurements of diffusion coefficients in progress. First results show that <100 mm point resolution should be reached P. Colas - Micromegas for HEP
Spherical TPC for neutrino detection FUTURE PROJECTS, R&D • NOSTOS project : • Neutrino oscillation from Tritium • Supernova detection, burst time structure • Coherence in n-A interactions to be tested at a reactor • Uses the longitudinal diffusion in the gas to estimate the distance to center Tritium source surrounded by a Micromegas P. Colas - Micromegas for HEP
Spherical TPC for neutrino detection FUTURE PROJECTS, R&D • Observe tritium ne oscillation and measure q13 • Measure the magnetic moment of the neutrino • Measure the weak mixing angle at low energy • Detect supernovae explosions P. Colas - Micromegas for HEP
Micromegas readout by silicon pixels FUTURE PROJECTS, R&D • CERN-NIKHEF-Saclay-Twente • MIPs have been seen in a combination micromeg.+Medipix • InGrid (integrated grid) project pillars on silicon 10 mm P. Colas - Micromegas for HEP
Neutron detection FUTURE PROJECTS, R&D • Use a converter to extract alphas • Numerous applications: neutron tomography, neutron detection in hostile environments P. Colas - Micromegas for HEP
New developments • Bulk Micromegas obtained by lamination of a woven grid on an anode with a photo-imageable film Large area robust detectors can be made for neutrino detection or photodetection P. Colas - Micromegas for HEP
New developments • Resistive layers (Ottawa-Saclay) Spreads the charge -> improves resolution with large pads (70 mm obtained with 2mm pads with 3keV X-rays) Might protect from discharges • New materials for meshes • Two-stage micromegas P. Colas - Micromegas for HEP
CONCLUSION • Existing Micromegas detectors perform well since over a year • Micromegas offers exciting perspectives for HEparticle detection: • High granularity and suppressed ion back-flow for TPCs • Single electron detection, with a very fast electron signal • Record-breaking time resolution • Low matter budget P. Colas - Micromegas for HEP