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Published byReginald Upton Modified over 9 years ago
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T. Lux
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13/12/2012 2 Charged particles X-ray (UV) Photons Cathode Anode Amplification Provides: xy position Energy (z position) e- CsI coating
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Right gas choice and pressure fundamental! Normally: noble gas + quencher gas Choice depends on: Tracking, photon detection or spectroscopy? Fast gas necessary? (still slower than solid state detectors) Is a high gain required? High rate environment? Is ageing an issue? Safety! Better if not flamable! Sensitive to impurities? Diffusion? -> affects point resolution Complication of the gas system? (open or closed for example) Price! 13/12/2012 3
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Argon, xenon or …? 13/12/2012 4 Stopping power larger in Xenon Better energy resolution in Xenon Argon much cheaper Etc. pressure but … pressure vessel + gas system attachment charge gain voltages …
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Infinite possibilities: CH4, CO2, C4H10, CF4, DME, … 13/12/2012 5
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Several advantages about the classical wire readout: Excellent spatial resolution ( amplification structures: ~100 m) Very good energy resolution Low material budget No ExB effects Cheap Can be produced in large quantities 13/12/2012 6 GEM
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1 stage amplification Excellent energy resolution and low threshold (600 eV) Time resolutions below 1 ns possible 13/12/2012 7
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Amplification within holes of Kapton foil coated with copper Normally operated in cascades -> better stability Can be operated in high rate environments (LHCb: 1 MHz/cm 2 ) 13/12/2012 8
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2005: Start R&D efforts for a MPGD TPC for T2K European GEM collaboration: UniGe, IFIC, INFN Bari, IFAE 13/12/2012 9 Thorsten Lux (IFAE/UAB)9/19 2 GEM tower 3 GEM each ~20x24 cm2 also small setup at IFAE
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13/12/2012 11 IFAE participated in setting up testbench characterization of ~ 90 MM modules ~12 m2 readout area nowadays focus on analysis
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13/12/2012 12 between two parallel meshes (G1,G2) a voltage is applied operated below the point where charge amplification sets in linear production of light (~172 nm for Xe) -> better energy resolution light is read out by PMT/APD/MPPC/… gain of 1000-2000 photons per e- at 10 bar possible G1 G2 Sensors e- Drift region EL gap Cathode
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13/12/2012 13 Started for a DB experiment in 2005 First stage: small HP chamber with 5 APDs Allowed to develop readout electronics Excellent energy resolution achieved Low threshold possible (8.2 ± 0.1)% FWHM xenon 13
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13/12/2012 14 Larger chamber with 25 APDs Pressure up-to 5 bar Focus on tracking
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2/11/2012 15IEEE 2012 Anaheim Very primitive cluster finder still Using the cosmic ray trigger
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Optimal imaging: MPGD with Pixel readout New project with CNM will start in January Si-MPGD coupled to MediPix chip 13/12/2012 16 MIPs δ-ray! 14 mm
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Choice of gas and pressure allows wide range of application Energy measurement: 0.6 keV – 100+ keV X-rays (with decreasing detection efficiency for higher energies) Photon counting at lower energies with coating Point resolutions down to 100-200 m possible Time resolutions below 1 ns possible High radiation hardness Count rates of 1 MHz/cm 2 possible MPGD allow to cover large areas to reasonable costs Gas detector knowledge available at IFAE but a gas detector for a ESRF source would require a dedicated R&D program 13/12/2012 17
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G.C. Smith, Gas-based detectors for synchrotron radiation, Journal of Synchrotron Radiation, Vol. 13, page 172-179, 2006 J.E. Bateman et al., A gas microstrip wide angle X-ray detector for application in synchrotron radiation experiments, NIM A, Volume 477, Issues 1–3, 21 January 2002, Pages 340-346 M. Kocsis et al., A novel gas-filled detector for synchrotron radiation applications, NIM A, Volume 563, Issue 1, 1 July 2006, Pages 172-176 M. Kocsis, The status of gas-filled detector developments at a third generation synchrotron source (ESRF), NIM A, Volume 471, Issues 1–2, 21 September 2001, Pages 103-108 13/12/2012 19
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The neutrino group at IFAE has built up in the last 7 years a significant amount gas detector knowledge: 2005-2008: MPGD R&D for the T2K TPCs 2008-2012: Electroluminescence detector R&D Future projects at IFAE: 2013-2015: Development of a Si-MPGD with MediPix readout 13/12/2012 20
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