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Developments of an Active target GEM-TPC for the AMADEUS experiment

Developments of an Active target GEM-TPC for the AMADEUS experiment. Outline: Micro-Pattern Gas Detector (MPDG) era; GEM: principle of operation; GEM-TPC in the AMADEUS experiment; Active target TPC: GEANT simulation; Prototype construction & PSI beam test ;

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Developments of an Active target GEM-TPC for the AMADEUS experiment

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  1. Developments of an Active target GEM-TPC for the AMADEUS experiment • Outline: • Micro-Pattern Gas Detector (MPDG) era; • GEM: principle of operation; • GEM-TPC in the AMADEUS experiment; • Active target TPC: GEANT simulation; • Prototype construction & PSI beam test ; • GEM-TPC performances: efficiency, spatial resolution, dE/dx; • New development: resistive anode GEM detector; • Conclusions Achievements and Perspective in Low-Energy QCD with Strangeness

  2. MPGDs: THE EARLY DAYS MSGC - MicroStrip Gas Chamber 200 mm A. Oed, NIMA 263(1988) 351 st ~9 ns • High E-values at the edge between insulator and strips  damages • Charge accumulation at the insulator  gain evolution vs time st ~12 ns GEM: F.Sauli, NIMA A386 (1997) 531 Later (~ 1999-2000): Passivation of the cathode edges  MSGD operational ! MICROMEGAS (MM) : Y. Giomataris et al, NIMA A376 (1996) 29 Achievements and Perspective in Low-Energy QCD with Strangeness

  3. MPGDs: THE EARLY DAYS MSGC - MicroStrip Gas Chamber 200 mm A. Oed, NIMA 263(1988) 351 • Why MPGDs? • High rates (granularity & occupancy, signal formation time) • Fine space resolution • Moving towards high luminosity / high precision experiments, i.e. towards the future • MPGDS are realized by photo-lithography technology, the same used for standard PCBs. st ~9 ns • High E-values at the edge between insulator and strips  damages • Charge accumulation at the insulator  gain evolution vs time st ~12 ns GEM: F.Sauli, NIMA A386 (1997) 531 Later (~ 1999-2000): Passivation of the cathode edges  MSGD operational ! MICROMEGAS (MM) : Y. Giomataris et al, NIMA A376 (1996) 29 Achievements and Perspective in Low-Energy QCD with Strangeness

  4. MPGDs @ LHC (I-Run) LHCb has been the first LHC experiment using GEM detectors for triggering purpose TOTEM uses GEM detectors for tracking purpose 24 triple-GEM 20x24 cm2 active area • The LNF group started the work on GEM in the 2000: • Non-standard gaps: 3/1/2/1 mm • Innovative gas mixture: Ar/CO2/CF4 = 45/15/40 • high time resolution (high efficiency ≈ 96% - in 25 ns) • No aging effects observed up to 2.2 C/cm2 during R&D Half-Moon Triple-GEM chambers Inner Ø: 80 mm Outer Ø 300 mm 40 Detectors (Helsinki-CERN) Achievements and Perspective in Low-Energy QCD with Strangeness

  5. MPGDs @ LHC (Upgrades) Small Wheel LHCb upgrade Rates in Hz/cm2 Rates at inner rim 1–2 kHz/cm2 GE2/1 GE1/1 ME0 Alice-TPC Achievements and Perspective in Low-Energy QCD with Strangeness

  6. GEM Principle of operation Achievements and Perspective in Low-Energy QCD with Strangeness

  7. Gas Electron Multiplier Cathode Field lines conversion and drift amplification By applying a voltage between the two copper sides an electric field as high as 100 kV/cmis produced in the holes acting as multiplication channels. Voltage ranging between 400 - 500 V induction Anode Readout Achievements and Perspective in Low-Energy QCD with Strangeness

  8. Cartesian Small angle Pads Triple-GEM detector Detector peculiarities: • The regions of conversion, multiplication and signal induction are physically distinct  freedom in readout design choice; • Signal is purely due to the motion of electrons in the induction region  no ion tail, fast signal; • Ions are quickly removed from multiplication region high rate capability • Multiplication is divided in 3 stepsrobustnessto discharges; • Lightdetector ( 3 ‰ X0 /GEM foil)

  9. AMADEUS EXPERIMENT Achievements and Perspective in Low-Energy QCD with Strangeness

  10. AMADEUS Experiment A novel idea of using an active target GEM-based TPC as a low mass target & tracker/PID detector at the same time is investigated Achievements and Perspective in Low-Energy QCD with Strangeness

  11. Active target GEM-TPC requirements GEM-TPC in AMADEUS GEANT Simulation Achievements and Perspective in Low-Energy QCD with Strangeness

  12. GEANT Simulation in Hydrogen gas target Achievements and Perspective in Low-Energy QCD with Strangeness

  13. Elastic Scattering: K± p  K ± p Kinematics for a 127 MeV/c kaon elastic scattering proton Both backward & forward scattering can be tracked in the target GEM-TPC Kaon Kaon proton Forward Scattering Backward Scattering Achievements and Perspective in Low-Energy QCD with Strangeness

  14. Performances in a pure H2 Active Target GEM-TPC Kaon Multiple-scattering Particle ID with dE/dx for Kaon & proton (a.u) proton kaon Angular distribution of diffused kaons < 1 mrad z= 0.085+-0.003 mm @ radius = 20 cm Achievements and Perspective in Low-Energy QCD with Strangeness

  15. GEM-TPC prototype Achievements and Perspective in Low-Energy QCD with Strangeness

  16. GEM-TPC R&D design A prototype of 10x10 cm2 active area and 15 cm drift gaphas been realized in a class 100 clean room. The detector is encapsulated inside a gas tight box (PERMAGLASS material) which allow to simply change the geometry and/or replace with new GEMs. Thewatercontamination is below 100 ppmv No value for O2contamination Windows Cathode Field Cage GEMs Foil Gas Tight Box Achievements and Perspective in Low-Energy QCD with Strangeness

  17. GEM-TPC construction: Assembly 10 cm Field Cage support GEMs Cathode electrode

  18. 4 Rows of 32 PADs PAD 3x3 mm2 GEM-TPC construction: Readout Pads readout by CARIOCA-GEM chip (Digital FEE) THR= 2 fC

  19. GEM-TPC Performances Achievements and Perspective in Low-Energy QCD with Strangeness

  20. Proton momentum Pion Momentum range Test beam @ PSI The PSI M1 beam is a (quasi) continuous high-intensity secondary beam: Pions/protonarrive in 1 ns-wide bunches every 20 ns. Characteristics of the piM1 beam line: Momentum range100-500 MeV/cMomentum resolution 1 % Spot size on target (FWHM): 15 mm (H)- 10 mm (V) The triggerconsisted of thecoincidence of three scintillatorsplaced at the edge of the detector ( 20 cm) and covering an area of about12x20 mm2. Another scintillator, 5 m far from the detector, allowed to performthe measurement of particle momentum by mean Time of Flight. An external tracker (100 μm) improves the tracking

  21. GEM: Ionization & Gain Successfully Tested @ PSI Laboratory Measurements The use of pure helium (no quencher) allows to work in stable operation until to gain of 3*104 Achievements and Perspective in Low-Energy QCD with Strangeness M. Poli Lener 21

  22. Hydrogen Helium Detector Efficiency High ionizing particle & high yield gas allow to reach higher detection efficiency at lower gain (Eff=1-e-np (*)) • The curves are fitted with negative exponential function • for different efficiency values the relative gain is reported as function of the simulated primary clusters • (G=ntot/np (*)) (*) F. Sauli. Yellow Report CERN 77-09, 1977

  23. Spatial Resolution Double Gaussian fit due to particles scattering in the detector gas volume/field cage walls σcore 200μm Spatial Resolution=√(σ2RES –σ2 trackers) Achievements and Perspective in Low-Energy QCD with Strangeness

  24. Time Over Threshold measurement The measurement of signal pulse width above a discriminator threshold may be used as a determination of the charge  Landau distribution as expected dE/dx resolution = 15% • Accepting the 40%lowest values, the most probable value of the trackcharge is correctly reproduce • forhigher values of the accepted fraction, theresolutiongetsworsedue to inclusion of hits from the Landau tail • forsmaller values, the effect is related to theloss in statistics. Achievements and Perspective in Low-Energy QCD with Strangeness

  25. Resolution Limit (*) PID & dE/dx measurements (Isobutane gas mixture) By simultaneously measuring the momentum of proton & pion (by means the time of flight) and thedeposited energy(by means the mean value of the truncated distribution), an estimation of the prototype to identify the particle crossing the detector has been performed ThedE/dx resolution is usually parametrized (*) as: σdE/dx ∝ Na *xb N=# of samples and x their length (3 mm). Assuming an average track length of 100 hits in AMADEUS, with 100 MeV/c pion and 40% of accepted fraction, we expect to measure adE/dx resolution of 10%. (*) W. Allison, J.H. Cobb., Ann. Rev. Nucl. Part. Sci 30 (1980) 253.

  26. e/ Separation power nE K/ K/p Particle Momentum (MeV/c) PID & dE/dx measurements Estimation with a dE/dx 10%

  27. LlMIT ON ACHIEVABLE TPC RESOLUTION • The physics limit of TPC resolution comes from transverse diffusion: Neff = effective electron statistics. • For best resolution, choose a gas with smallest diffusion ExB systematics limits wire/pad TPC resolution Pad width would limits MPGD TPC resolution Micro PatternGas Detector Proportionalwire Cathode pads width w Anode pads width w Direct signal on the MPGD anode pad Induced cathode signal determined by geometry For small diffusion, less precise centroid for wide pads Accurate centroid determination possible with wide pads

  28. R.K.Carnegie et.al., NIM A538 (2005) 372 K. Boudjemline et.al., NIM A574 (2007) 22 GEM with direct charge readout GEM with charge dispersion readout Charge dispersion in a GEM with a resistive anode Modified GEM anode with a high resistivity film bonded to a readout plane with an insulating spacer 2 mm wide pads 2 mm wide pads Achievements and Perspective in Low-Energy QCD with Strangeness

  29. Conclusions • The GEM-TPC prototype is successfully tested at the M1 test beam facility of PSI withisobutane-based gas mixturesand pure Helium: • Efficiency > 99% and spatial resolution ≈ 200 μm withisobutane-based gas mixture have been measured; • With pure Heliumgas a detector stability up to3*104has been achieved  efficiency  97% & spatial resolution  270 µm; • Particle Identification capability & dE/dx resolution  10% with isobutane gas mixtures have been achieved  High separation µ//K/p in AMADEUS environment; • Charge DispersionTechnique by means of resistive anode will be soon validated in order to reach a better spatial resolution and todecrease the number of FEE channels; Achievements and Perspective in Low-Energy QCD with Strangeness

  30. THANKS Achievements and Perspective in Low-Energy QCD with Strangeness

  31. Achievements and Perspective in Low-Energy QCD with Strangeness

  32. Field Cage Effect on detector performance Detector Efficiency Field Cage Edge effect Efficiency per Row

  33. Garfield Garfield GEM Detector Simulation Garfield GARFIELD is a powerfull simulation tool: primary ionization, diffusion, attachment,multiplication, E-/ion drift, induced & direct signal, ecc Achievements and Perspective in Low-Energy QCD with Strangeness

  34. GEANT Simulation of a pure H2 Active Target GEM-TPC 0.6 tesla Kapton Kapton Copper Scintillator Hydrogen gas:1 atm 40 cm 20 cm Berylium beam pipe: 20 mm - 20.5 mm Plastic Scintillator : 40 mm - 40.5 mm Kapton target wall : 49.95 mm - 50. mm Copper Cage : 49.94 mm - 49.95 mm Hydrogen gas : 50 mm - 200 mm Performed with H. Shi

  35. Field Cage Effects Low and/or not full detection efficiency has been measured on the edge of each pad rows. - the first and the last pad of each rows collect about 2/3 of the charge with respect to the other pads of the row; - the primary electrons produced in the drift gas and drifting toward the first GEM can be collected by the internal strips of the field-cage. Garfield All these effects are fully reduced drifting away from the field-cage by 5 mm

  36. GEM-TPC construction: Field Cage 32 copper strips on both sides of Kapton foil (strip pitch 2.5 mm) 15 cm Cylindrical mould of the Field cage in vacuum bag 30 cm The Field Cage has been produced with the same C-GEM technique (*) 100 M resistor (*) G. Bencivenni et al., NIM A 572 (2007) 168

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