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Using Multi-gap Resistive Plate Chamber as TOF
WU, Jian Department of Modern Physics University of Science & Technology of China 2018/9/22 Talk for EM group 伍健
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Outline Introduction MRPC as TOF Results & Conclusions Why TOF
Options of TOF MRPC as TOF Working mechanism Simulation & design Major parameters MRPC based TOF tray Results & Conclusions 2018/9/22 Talk for EM group 伍健
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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. QGP – Brisure de la symetrie chirale – hadronisation - Evolution vers notre monde Besoin de tres hautes energies, comme au LHC, pour remonter loin dans le temps. Mais il y a aussi besoin de comprendre les phenomenes a plus basse energie avant ! 2018/9/22 Talk for EM group 伍健
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Relativistic Heavy-Ion Collider at BNL
2018/9/22 Talk for EM group 伍健
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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 2018/9/22 Talk for EM group 伍健
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Time-Of-Flight Detector in Heavy-Ion Exp.
STAR at RHIC ALICE at LHC High multiplicity : 103 – 104 particles produced Large coverage : ~102 m Strong magnetic field : 0.5 – 2 T High event rate: 102 – 103 Hz/cm2 2018/9/22 Talk for EM group 伍健
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p/ Separation Momentum: 3GeV/c Flight path length: 277cm
t=432ps(prediction) t=441ps(experiment) 2018/9/22 Talk for EM group 伍健
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Options of TOF To reduce occupancy ~10%, need small size strip 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 2018/9/22 Talk for EM group 伍健
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Gaseous Detector Advantages Important detector Application fields
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 2018/9/22 Talk for EM group 伍健
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Passage of Particles through Matter
Photon cross section charged particles (other than electrons) energy lose electrons energy lose 2018/9/22 Talk for EM group 伍健
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Gas Gain vs. High Voltage
Geiger Counter MWPC MRPC 2018/9/22 Talk for EM group 伍健
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Multi-Wire Proportional Chamber (MWPC)
G .Charpak, 1992 Nobel Prize for invention and application of MWPC in 1968 2018/9/22 Talk for EM group 伍健
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Resistive Plate Chamber
Fast trigger, good time resolution (<100ps for 300m gap in streamer mode, ~1ns for 2mm gap in avalanche mode), high rate capacity (>104s-1cm-2) 2018/9/22 Talk for EM group 伍健
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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 2018/9/22 Talk for EM group 伍健
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RPC Application – ATLAS Muon Trigger System
HV Bakelite Plates Foam X readout strips Gas Graphite electrodes PET spacers Y readout strips Grounded plane Gas mixture: C2H2F4 94.7% - C4H10 5% - SF6 0.3% Avalanche regime 2018/9/22 Talk for EM group 伍健
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MRPC Principle – from RPC to 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 M.C.S. Williams et al., Nucl. Instr. and Meth. A 374 (1996) 132 2018/9/22 Talk for EM group 伍健
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MRPC Basic Structure 2018/9/22 Talk for EM group 伍健
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Feedback Effect Normal Operation
Abnormal Operation: Feedback effect recovers the right electric potential 2018/9/22 Talk for EM group 伍健
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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 (2105m/s) 2018/9/22 Talk for EM group 伍健
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A MRPC Prototype Strip size:3.0cm×3.1cm gap:6×0.25mm 2018/9/22
Talk for EM group 伍健
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Beam Test at CERN PS-T10 facility
2018/9/22 Talk for EM group 伍健
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Test Setup MRPC prototype
Incident particle: 7GeV/c (~80%) and p(~20%) Tracking resolution: <0.5mm Timing resolution: 30ps(trigger), 25ps(system) 2018/9/22 Talk for EM group 伍健
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Signal Readout 2018/9/22 Talk for EM group 伍健
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Charge (ADC) and Timing (TDC) Spectra
2018/9/22 Talk for EM group 伍健
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Detection Efficiency ~97%
HV Plateau Detection Efficiency ~97% Time resolution ~60ps Plateau range ~1KV 2018/9/22 Talk for EM group 伍健
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Time Walk Time walk : timing change due to gas gain / drift velocity variation at different E-field 2018/9/22 Talk for EM group 伍健
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Position Effect 2018/9/22 Talk for EM group 伍健
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Speed of signal propagation on MRPC strip:40-45ps/cm
2018/9/22 Talk for EM group 伍健
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p/ Separation Momentum: 3GeV/c Flight path length: 277cm
t=432ps(prediction) t=441ps(experiment) 2018/9/22 Talk for EM group 伍健
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Excellent performance to ~300Hz/cm2 Expected rate at STAR ~100Hz/cm2
Rate Capacity Excellent performance to ~300Hz/cm2 Expected rate at STAR ~100Hz/cm2 2018/9/22 Talk for EM group 伍健
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Operation in Different Gas Mixtures
3 kinds of gas mixtures are investigated : %C2F4H2 + 5%iso-Butane +5%SF6, 94.7%C2F4H %iso-Butane and 100%C2F4H2 2018/9/22 Talk for EM group 伍健
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Double-layer MRPC 2018/9/22 Talk for EM group 伍健
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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 2018/9/22 Talk for EM group 伍健
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Performance of Double-layer MRPC
Better Efficiency ! Better time resolution ! ALICE’s final design, but not STAR’s – lack of structural space 2018/9/22 Talk for EM group 伍健
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PID at STAR by dE/dx 2018/9/22 Talk for EM group 伍健
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Achievement 2018/9/22 Talk for EM group 伍健
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MRPC Design for STAR TOF
Strip size: 3.15cm×6.3cm Gas gap: 6×0.22mm 2018/9/22 Talk for EM group 伍健
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Position in a Tray Cover 6 in azimuth and 1 in pseudo-rapidity
at radius ~ 2.2m 2018/9/22 Talk for EM group 伍健
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Photographs 2018/9/22 Talk for EM group 伍健
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Results & conclusions Proton/Kaon separation is extended from 1.1GeV/c to 3GeV/c Kaon/Pion from 0.6GeV/c to more than 1.6GeV/c with TOFr 2018/9/22 Talk for EM group 伍健
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More on Electron Identification
Use velocity cut (from TOF) to select fast particle – electrons are ALWAYS fast !! 2018/9/22 Talk for EM group 伍健
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Compton or photoelectric interaction
A Small Animal PET with (M)RPCs The scanner The detection Compton or photoelectric interaction .... e- Modules of n-stacked timing RPCs. High acceptance geometry > 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 2018/9/22 Talk for EM group 伍健 4
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High voltage distribution
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 2018/9/22 Talk for EM group 伍健 11
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Thank you ! 2018/9/22 Talk for EM group 伍健
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Backup Slides 2018/9/22 Talk for EM group 伍健
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Drift Chamber 2018/9/22 Talk for EM group 伍健
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Signal Induction 2018/9/22 Talk for EM group 伍健
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Time Projection Chamber
2018/9/22 Talk for EM group 伍健
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MicroStrip Gas Chamber
2018/9/22 Talk for EM group 伍健
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MSGC Advantage 2018/9/22 Talk for EM group 伍健
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Gas Electron Multiplier
2018/9/22 Talk for EM group 伍健
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GEM E-Field 2018/9/22 Talk for EM group 伍健
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2018/9/22 Talk for EM group 伍健
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Time-Over-Threshold 2018/9/22 Talk for EM group 伍健
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MAXIM 3760 Bandwidth : 560MHz Max gain : ~6500 2018/9/22
Talk for EM group 伍健
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ALICE at LHC – the Muon spectrometer
HMPID TRD TPC ITS TOF PHOS MUON SPECTROMETER MUON TRIGGER MUON TRIGGER Search for (muon) tracks Compute their deviation Pt cut for background subtraction Detector : 72 RPC in streamer mode 120 m², 2 stations, 4 planes Response time : 700 ns (ALICE L0 trigger) The muons spectrometer hosts a muons trigger system. The electronics associated searches for muons tracks and compute their deviation. A cut on the deviation then allows us to perform a Pt cut on each track The detector is formed by 2 stations. Each of them contains 2 planes of RPC functioning in streamer mode. The response time of the trigger is 700 ns. 2018/9/22 Talk for EM group 伍健
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