MWPC’s, GEM’s or Micromegas for AD transfer and experimental lines December 5, 2018 BDI-Day (Kondo GNANVO)
BDI-Day (Kondo GNANVO) Contents MWPC’s on the AD transfer and experimental lines. New Gaseous Detectors to replace the MWPC’s. MWPC, GEM, Micromegas : Performances. Modification of GEM to replace the MWPC’s Conclusion December 5, 2018 BDI-Day (Kondo GNANVO)
BDI-Day (Kondo GNANVO) AD Overview December 5, 2018 BDI-Day (Kondo GNANVO)
AD Experimental Lines Layout Transfer Line 7000 + Experimental lines DE1, DE2, DE3, DE4 16 MWPC’s for the extraction and experimental lines. MWPC’s in a tank with an IN & OUT system Machine steering Beam position and size measurements. MWPC’s perturbs the measurement and destructs the beam Old chambers and electronics. Performances limited for high Intensity. MWPC fragile and maintenance December 5, 2018 BDI-Day (Kondo GNANVO)
Multi Wire Proportional chamber Limitations of MWPC : Gain drops at high count rate (intrinsic ) 1D detector2 detectors for a 2D profile Slow response and saturation (intrinsic) Spatial resolution limited (mechanical) Wires structure are fragile and subject to aging AB/BDI/EA (J. Spanggaard) 2D MWPC Position from the delay between 2 extremities of a delay line connected to the cathode wire. December 5, 2018 BDI-Day (Kondo GNANVO)
BDI-Day (Kondo GNANVO) GEM & Micromegas GEM : Gas Electron Multiplier Micromegas : Micro Mesh Gaseous Detector Sauli (CERN EP/GDD 1997) Copper coated Kapton foil with high density of holes PCB technology PCB technology Flexibility for Read Out Giomataris (Saclay 1996) Metallic Mesh as amplification cathode PCB technology for Read Out Both GEM and Micromegas are advanced technology Detectors already used in some HEP experiments (COMPASS, CAST etc…) GEM is manufactured at CERN (Sauli) December 5, 2018 BDI-Day (Kondo GNANVO)
BDI-Day (Kondo GNANVO) GEM Detector Drift zone Transfer zone 75 µm 100-200 µm Holes density = Electron microscope view of a GEM foil December 5, 2018 BDI-Day (Kondo GNANVO)
BDI-Day (Kondo GNANVO) GEM flexible readout Different 2D Readout Same PCB technology as GEM Flexibility for the 2D readout electrodes Cartesian Stereo Angle Pads 2D Cartesian readout 350 µm 400 µm 80 µm Substrate Kapton Copper COMPASS : equal charge sharing between coordinates Correlation between charges amplitudes = multiple hits measurements Good spatial resolution December 5, 2018 BDI-Day (Kondo GNANVO)
BDI-Day (Kondo GNANVO) Micromegas 2D readout 2D readout Charge division of the avalanche on the resistive strips Ni-Cr layer (1µm) on Kapton foil (20 µm) glued on epoxy box Epoxy 400 µm to 1.5 mm (most comonly used) Glass 10 to 50 µm (Harsh Irradiation condition ?) Kapton 20 to 5 µm on a Honeycomb structure (Is it possible?). Strip Substrate December 5, 2018 BDI-Day (Kondo GNANVO)
GEM foil as a preamplification stage Micromegem : Mesh replaced by a GEM foil => double amplification GEM + MSGG Multi GEM Operation at low voltage Higher gain Avoid (reduce) discharge Reduce charging up effect of the GEM foil December 5, 2018 BDI-Day (Kondo GNANVO)
BDI-Day (Kondo GNANVO) GEM & Micromegas : Gain Gain & Discharge probability GEM Micromegas December 5, 2018 BDI-Day (Kondo GNANVO)
BDI-Day (Kondo GNANVO) GEM & Micromegas : Gain Gain stability GEM MWPC, MSGC & Micromegas December 5, 2018 BDI-Day (Kondo GNANVO)
BDI-Day (Kondo GNANVO) GEM Signal Electrons Ions NO POSITIVE ION TAIL Very good multi-track resolution Full Width 20 ns (for 2 mm gap) The total length of the detected signal corresponds to the electron drift time in the induction gap: Double GEM, normal operating conditions (EDRIFT=200 V/cm), Ion Feedback is ~ 1.5% December 5, 2018 BDI-Day (Kondo GNANVO)
GEM & Micromegas : Spatial resolution GEM Spatial resolution Negligible effects (Geometry of the detectors) GEM X-Y Correlation Useful for multi track ambiguity resolution Y position measurement With resistive strips method Resolution > 300 µm Depend on strip Length December 5, 2018 BDI-Day (Kondo GNANVO)
MWPC, GEM & Micromegas Performances Rate capability 10^4Hz/mm^2 >5x10^5Hz/mm^2 10^6Hz/mm^2 Gain High 10^6 low 10^3 (single) > 10^5 (multi GEM) High > 10^5 Gain stability Drops at 10^4Hz/mm^2 Stable over 5*10^5Hz/mm^2 Stable over 10^6Hz/mm^2 2D Readout ? Not really Yes and flexible Yes, not flexible Position resolution > 200 µm (analog) 50 µm (analog) Good < 80 µm Time resolution ~ 100 µs < 100 ns Magnetic Field effect High Low Cost Expensive, fragile Cheap, robust December 5, 2018 BDI-Day (Kondo GNANVO)
Modification of GEM to replace the MWPC’s What is available now ? Modifications of the GEM Detector geometry to fit the MWPC’s vacuum tank Drift cathode (Nickel mesh) Readout connections to fit the MWPC’s electronics December 5, 2018 BDI-Day (Kondo GNANVO)
BDI-Day (Kondo GNANVO) Conclusion 2D Micro Pattern Gaseous detectors to replace MWPC’s on the AD experimental lines. GEM detectors and Micromegas are the most promising. Low cost and high performances. More accurate beam’s position and beam size measurement. But not less destructive for the beam. Different techniques for the beam’s position size measurement SEM’s, Scintillators, Wire scanners, etc… They are destructives too ! Not 2D measurement ! Not necessary easy to implement ! For the immediate future Development of a new GEM detector suitable for the AD MWPC vacuum thank December 5, 2018 BDI-Day (Kondo GNANVO)
BDI-Day (Kondo GNANVO) END December 5, 2018 BDI-Day (Kondo GNANVO)