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Using M ulti-gap R esistive P late C hamber as TOF

Using M ulti-gap R esistive P late C hamber as TOF. WU, Jian Department of Modern Physics University of Science & Technology of China. Outline. Introduction Why TOF Options of TOF MRPC as TOF Working mechanism Simulation & design Major parameters MRPC based TOF tray

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Using M ulti-gap R esistive P late C hamber as TOF

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  1. Using Multi-gap Resistive Plate Chamber as TOF WU, Jian Department of Modern PhysicsUniversity of Science & Technology of China Talk for EM group 伍健

  2. Outline • Introduction • Why TOF • Options of TOF • MRPC as TOF • Working mechanism • Simulation & design • Major parameters • MRPC based TOF tray • Results & Conclusions Talk for EM group 伍健

  3. Heavy Ion Collisions to Go Back in Time • In the Big-Bang theory, our universe is in expansion since 15 billions of years. • Only ultra-relativistic heavy ion collisions • could allow to recreate a small volume of nuclear matter such as the one having existed in the first micro seconds of our universe, the Quark Gluon Plasma (QGP) , making then possible the study and the evolution of this phase of matter. Talk for EM group 伍健

  4. Relativistic Heavy-Ion Collider at BNL Talk for EM group 伍健

  5. Solenoidal Tracker At RHIC • Great interest in large acceptance PID over an extended pT range • full TOF replaces the existing Central Trigger Barrel. • covers the TPC tracking detector • Based on Multi-gap Resistive Plate Chambers (MRPC) • prototype detector: TOFr Talk for EM group 伍健

  6. Time-Of-Flight Detector in Heavy-Ion Exp. STAR at RHIC ALICE at LHC High multiplicity : 103 – 104 particles produced Large coverage : ~102 m2 Strong magnetic field : 0.5 – 2 T High event rate: 102 – 103 Hz/cm2 Talk for EM group 伍健

  7. p/ Separation Momentum: 3GeV/c Flight path length: 277cm t=432ps（prediction） t=441ps（experiment） Talk for EM group 伍健

  8. Options of TOF To reduce occupancy ~10%, need small size strip  105-106 channels “Standard” TOF system built of fast scintillators plus phototubes would cost too much ! ( ~ 80 MCHF for ALICE) Gaseous detectors route to large area detectors at affordable price Talk for EM group 伍健

  9. Advantages Can be made at almost any shape and size Low noise Excellent dynamics range Can make simultaneous measurements of energy and position Important detector Charged particles X- and - ray Visible light Application fields particle & nuclear physics space-borne astro-particle physics medical imaging x-ray crystallography environmental monitoring Gaseous Detector Talk for EM group 伍健

  10. Passage of Particles through Matter Photon cross section charged particles (other than electrons) energy lose electrons energy lose Talk for EM group 伍健

  11. Gas Gain vs. High Voltage Geiger Counter MWPC MRPC Talk for EM group 伍健

  12. Multi-Wire Proportional Chamber (MWPC) G .Charpak, 1992 Nobel Prize for invention and application of MWPC in 1968 Talk for EM group 伍健

  13. Resistive Plate Chamber Fast trigger, good time resolution (<100ps for 300m gap in streamer mode, ~1ns for 2mm gap in avalanche mode), high rate capacity (>104s-1cm-2) Talk for EM group 伍健

  14. Simulation Procedure - step by step • Set time step dt, and position step dx = dt·vdrift • Get primary cluster position (exponential distribution) according to cluster density • Get primary cluster size following the size distribution • For each electron in each cluster, multiplies following Townsend’s law and the avalanche fluctuation distribution (include space charge effect) • Calculate the signal induced by using Ramo’s theorem • Induced current is convolved with FEE response, then passes to discrimination to provide TDC timing, ADC is also calculated Talk for EM group 伍健

  15. X readout strips Gas HV Bakelite Plates Foam Y readout strips PET spacers Graphite electrodes RPC Application – ATLAS Muon Trigger System Grounded plane Gas mixture: C2H2F4 94.7% - C4H105% - SF6 0.3%Avalanche regime Talk for EM group 伍健

  16. MRPCPrinciple – from RPCto MRPC Work in avalanche mode for high rate capacity Thin gas gap to improve time resolution Quench avalanche process to avoid streamer Idea comes true in 1996M.C.S. Williams et al., Nucl. Instr. and Meth. A 374 (1996) 132 Talk for EM group 伍健

  17. MRPCBasic Structure Talk for EM group 伍健

  18. Feedback Effect Normal Operation   Abnormal Operation: Feedback effect recovers the right electric potential Talk for EM group 伍健

  19. Gas Parameters for MRPC Operation Gas Mixture: 90%C2F4H2 + 5%iso-Butane + 5%SF6 Operation E-field : ~ 110 kV/cm Effective Townsend Coefficient :  ~ 1400 /cm Electron drift velocity ~ 200 microns/ns (2105m/s) Talk for EM group 伍健

  20. A MRPC Prototype Strip size：3.0cm×3.1cm gap：6×0.25mm Talk for EM group 伍健

  21. Beam Test at CERN PS-T10 facility Talk for EM group 伍健

  22. Test Setup MRPC prototype Incident particle: 7GeV/c (~80%) and p(~20%) Tracking resolution: <0.5mm Timing resolution: 30ps(trigger), 25ps(system) Talk for EM group 伍健

  23. Signal Readout Talk for EM group 伍健

  24. Charge (ADC) and Timing (TDC) Spectra Talk for EM group 伍健

  25. HV Plateau Detection Efficiency~97% Time resolution~60ps Plateau range~1KV Talk for EM group 伍健

  26. Time Walk Time walk : timing change due to gas gain / drift velocity variation at different E-field Talk for EM group 伍健

  27. Position Effect Talk for EM group 伍健

  28. Signal Propagation Speed of signal propagation on MRPC strip：40-45ps/cm Talk for EM group 伍健

  29. p/ Separation Momentum: 3GeV/c Flight path length: 277cm t=432ps（prediction） t=441ps（experiment） Talk for EM group 伍健

  30. Rate Capacity Excellent performance to~300Hz/cm2 Expected rate at STAR~100Hz/cm2 Talk for EM group 伍健

  31. Operation in Different Gas Mixtures 3 kinds ofgas mixtures are investigated : 90%C2F4H2 + 5%iso-Butane +5%SF6, 94.7%C2F4H2 + 5.3%iso-Butane and 100%C2F4H2 Talk for EM group 伍健

  32. Double-layer MRPC Talk for EM group 伍健

  33. An Example Cross section of double-stack MRPC for the ALICE TOF 130 mm active area 70 mm honeycomb panel Flat cable connector Differential signal sent from strip to interface card (10 mm thick) PCB with cathode pickup pads external glass plates 0.55 mm thick internal glass plates (0.4 mm thick) PCB with anode pickup pads Mylar film (250 micron thick) 5 gas gaps of 250 micron PCB with cathode pickup pads M5 nylon screw to hold fishing-line spacer Honeycomb panel (10 mm thick) connection to bring cathode signal Silicon sealing compound to central read-out PCB Talk for EM group 伍健

  34. Performance of Double-layer MRPC Better Efficiency ! Better time resolution ! ALICE’s final design, but not STAR’s – lack of structural space Talk for EM group 伍健

  35. PID at STAR by dE/dx Talk for EM group 伍健

  36. Achievement Talk for EM group 伍健

  37. MRPC Design for STAR TOF Strip size： 3.15cm×6.3cm Gas gap： 6×0.22mm Talk for EM group 伍健

  38. Position in a Tray Cover 6 in azimuth and 1 in pseudo-rapidity at radius ~ 2.2m Talk for EM group 伍健

  39. Photographs Talk for EM group 伍健

  40. Results & conclusions Proton/Kaon separation is extended from 1.1GeV/c to 3GeV/cKaon/Pion from 0.6GeV/c to more than 1.6GeV/c with TOFr Talk for EM group 伍健

  41. More on Electron Identification Use velocity cut (from TOF) to select fast particle – electrons are ALWAYS fast !! Talk for EM group 伍健

  42. Compton or photoelectric interaction e-  .... ASmallAnimal PET with (M)RPCs The scanner The detection • Modules of n-stacked timing RPCs. • High acceptancegeometry > 90%. • Fully 3D measurement of the interaction point of the photon. No parallax error. • Very high spatial resolution < 0.5 mm (FWHM). • High timing resolution < 1 ns, improve the random events rejection. • Efficiency  10% (sensitivity  6 cps/KBq). • Low cost vs. scintillator based implementations. • Compatible with Magnetic Resonance Imaging. Incident photon Gas gap Alberto Blanco Talk for EM group 伍健 4

  43. Prototype Charge-sensitive electronics allow inter-strip positioning interpolation 32 strips 16 plates ....... ....... 16 stacked (M)RPCs. Z X, Z Sensitivity High voltage distribution X Talk for EM group 伍健 11

  44. Thank you ! Talk for EM group 伍健

  45. Backup Slides Talk for EM group 伍健

  46. Drift Chamber Talk for EM group 伍健

  47. Signal Induction Talk for EM group 伍健

  48. Time Projection Chamber Talk for EM group 伍健

  49. MicroStrip Gas Chamber Talk for EM group 伍健

  50. MSGC Advantage Talk for EM group 伍健

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