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New MRPC prototypes developed in Tsinghua Unversity

New MRPC prototypes developed in Tsinghua Unversity. Huangshan Chen (Tsinghua Unversity). Outline. High rate MRPC modules Performance of low resistivity silicate glass Pad readout MRPC Strip readout MRPC MRPC module for STAR-MTD Module structure Cosmic-ray test setup and result

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New MRPC prototypes developed in Tsinghua Unversity

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  1. New MRPC prototypes developed in Tsinghua Unversity Huangshan Chen (Tsinghua Unversity)

  2. Outline • High rate MRPC modules • Performance of low resistivity silicate glass • Pad readout MRPC • Strip readout MRPC • MRPC module for STAR-MTD • Module structure • Cosmic-ray test setup and result • Beam test setup and result • Summary STAR MTD Workshop, USTC, Hefei, China

  3. High rate MRPC modules STAR MTD Workshop, USTC, Hefei, China

  4. FAIR – CBM TOF CBM • Full TOF system: • Time resolution sT ~ 80 ps • Efficiency > 95 % • Rate capability < 20 kHz/cm2 • Acceptable cross-talk and charge-sharing. • Low power electronics (~75.000 channels). • Sufficient space resolution Timing RPC : • Active area: A = 170 m2 • Counter time resolution: sT ~ 50 ps • Rate capability: R ~ 0.5 - 20 kHz/cm2 • Granularity: DA ~ 6 - 100 cm2 • Operation mode: free running STAR MTD Workshop, USTC, Hefei, China

  5. World map of MRPC’s rate capability STAR MTD Workshop, USTC, Hefei, China

  6. Specification of low resistivity silicate glass Specifications: Maximal dimension: 50cm×50cm Bulk resistivity: ~1010.cm Standard thickness: 0.5mm--2mm Thickness uniformity: 0.02mm Permittivity : ~10 Surface roughness: <10nm DC measurement: very stable STAR MTD Workshop, USTC, Hefei, China

  7. Scanned images of low resistive silicate glass Y Ryi X 3-D image 2-D image • Ra=0.873 nm • Rq=1.10nm • Ry=9.30nm L STAR MTD Workshop, USTC, Hefei, China

  8. Low resistive silicate glass Bulk resistivity: 3-4×1010Ωcm The accumulated charge was 1 C/cm2, roughly corresponding to the CBM life-time over 5 year operation at the maximum counting rate. T = 28 C° HV = 1kV Using low resistive silicate glass instead of common glass is an innovative way of improving the rate capability of Resistive Plate Chambers. STAR MTD Workshop, USTC, Hefei, China

  9. Pad readout MRPC – MRPC #1 3mm 60mm 31.5mm STAR MTD Workshop, USTC, Hefei, China

  10. Pad readout MRPC – MRPC #2 3mm 30mm 31.5mm 15.5mm STAR MTD Workshop, USTC, Hefei, China

  11. Beam test setup at GSI-Darmstadt Tests were performed at GSI-Darmstadt under uniform irradiation by secondary particles stemming from proton reactions at 2.5 GeV. The higher rates can be obtained by moving the RPCs up closer to the main beam. Gas mixture: Freon/iso-butane/SF6 : 96.5%/3%/0.5% 2.5GeV STAR MTD Workshop, USTC, Hefei, China

  12. Counting rate • The beam comes in spills. • We take the mean of the PMT and MRPC measurements as a sound reference for rate estimation : • PMT rate: 0.8~20 kHz/cm2 • MRPC rate: 2~30 kHz/cm2 • Mean rate: 1.4~25 kHz/cm2 STAR MTD Workshop, USTC, Hefei, China

  13. Time difference Timediff =TMRPC#1-TMRPC#2 Resolution of time difference become worse with the raise of rate. STAR MTD Workshop, USTC, Hefei, China

  14. Charge distribution of MRPC#2 MRPC#2: 10-gap With rate increasing, the average charge decreases, which leads to a relativity lower efficiency. STAR MTD Workshop, USTC, Hefei, China

  15. HV scan at 1.4kHz/cm2 • The efficiency is higher than 90% and the time resolution remains below 90ps once at the efficiency plateau. • By means of using more gas gaps, the 10-gap RPC shows a better performance. MRPC#1: 6-gap MRPC#2: 10-gap STAR MTD Workshop, USTC, Hefei, China

  16. Rate scan 90% 110ps 76% 85ps The efficiencies and time resolutions deteriorate with the counting rate. MRPC#2 yields much better results: 90% efficiency, 85ps resolution at the rate of ~25 kHz/cm2. STAR MTD Workshop, USTC, Hefei, China

  17. Strip readout module structure: MRPC#3 & MRPC#4 interval: 3mm 22mm 240mm STAR MTD Workshop, USTC, Hefei, China

  18. Surface resistivity distribution of electrode 20 points: minimum: 2.9M /□ maximum: 5.8M /□ average: 4.3M /□ STAR MTD Workshop, USTC, Hefei, China

  19. Beam test layout MRPC#3：silicate glass MRPC#4: common glass Target Tsinghua RPC Silicon Main beam PM12 PM5 PM34  10 m STAR MTD Workshop, USTC, Hefei, China

  20. HV scan Tdiff =T MRPC#3-T MRPC#4 EffMRPC#3 ≈ EffMRPC#4 > 95%, σMRPC#3 ≈ σMRPC#4 ≈ σdiff /sqrt(2)< 80ps STAR MTD Workshop, USTC, Hefei, China

  21. "or" eff 100 strip1 strip2 80 strip3 "and" eff 60 Efficiency(%) 40 20 0 -20 -10 0 10 20 30 40 Rpcy(mm) Position Scan MRPC#3 3 2 1 Rpcy MRPC#4 STAR MTD Workshop, USTC, Hefei, China

  22. Position resolution T1 T2 DeltaT=(T2-T1)/2 • Using the tracking, we get the signal propagation velocity: ~ 61ps/cm • Position resolution: <5 mm STAR MTD Workshop, USTC, Hefei, China

  23. Efficiency correction with tracking 2×4 (cm2) 1×2 (cm2) MRPC#3 MRPC#4 Efficiency: 95% 97% STAR MTD Workshop, USTC, Hefei, China

  24. MRPC module for STAR-MTD STAR MTD Workshop, USTC, Hefei, China

  25. Module structure 1 2 3 Strip width: 38 mm 4 5 Interval: 6 mm 6 7 8 9 10 11 Strip length: 900mm 12 STAR MTD Workshop, USTC, Hefei, China

  26. Cosmic-ray test system layout 1 2 5cm*5cm*20cm scintillators Above and below the module 3 2cm*2cm*4cm scintillators above and below the module 4 5 6 7 8 9 10 11 12 Gas mixture: 95%Freon/5%iso-butane Or 94%Freon/5%iso-butane/1%SF6 Gas flow: 50ml/min STAR MTD Workshop, USTC, Hefei, China

  27. Efficiency and time resolution 95%Freon/5%iso-butane : efficiency>95% @ 96.3kV/cm (HV=±7.22 kV), time resolution <100ps 94%Freon/5%iso-butane/1%SF6 : efficiency>95% @ 98.3 kV/cm (HV=±7.37 kV), time resolution ~ 75ps STAR MTD Workshop, USTC, Hefei, China

  28. Noise level Filter circuit 94%Freon/5%iso-butane/1% SF6, E=104 kV/cm (HV=±7.8kV) • Having a filter circuit on HV electrode, the noise is reduced to a very low level! • Most of noise level are smaller than 1.0 Hz/cm2. STAR MTD Workshop, USTC, Hefei, China

  29. Noise level 95%Freon/5%iso-butane 94%Freon/5%iso-butane/1% SF6 Noise < 0.6 Hz/cm2 @ (HV=±7.2kV, eff~95%) Noise < 0.6 Hz/cm2 @ (HV=±7.4kV, eff ~95%) STAR MTD Workshop, USTC, Hefei, China

  30. Uniformity 94%Freon/5%iso-butane/1% SF6 @ 100 kV/cm (HV=±7.5 kV) Efficiency ~ 95% Time resolution :60~80ps Not bad uniformity! STAR MTD Workshop, USTC, Hefei, China

  31. Beam-test area at IHEP, BEIJING STAR MTD Workshop, USTC, Hefei, China

  32. Detector system at experiment area position Trigger and PID T0(trigger) and MRPC MRPC C0 MRPC MWPC PMT3&4 PMT1&2 Gas mixture: 90%Freon/5%iso-butane/5%SF6 @ 150ml/min STAR MTD Workshop, USTC, Hefei, China

  33. Beam Trigger = SC1+SC2-C0+T0  + p (600MeV) Rate ~ 1-20/min Distinguish between pion and proton using the charge spectrum of PMTs STAR MTD Workshop, USTC, Hefei, China

  34. Efficiency & time resolution for proton Efficiency > 95% @ ~87 kV/cm (HV= ±6.525 kV) Time resolution ~ 70ps STAR MTD Workshop, USTC, Hefei, China

  35. Trigger scan -- vertical 9 Move trigger: 5mm/step @ 96kV/cm (HV=±7.2kV) 10 11 12 Efficiency Time resolution STAR MTD Workshop, USTC, Hefei, China

  36. Trigger scan -- horizontal 9 Move trigger: 5cm/step @ 90.67 kV/cm (HV= ±6.8 kV) 10 11 12 T_diff/2 = t0+dx/v 1/v = 55.96 ps/cm Efficiency ~ 100% Time resolution ~ 55ps STAR MTD Workshop, USTC, Hefei, China

  37. Summary • High rate MRPC modules • Low resistive silicate glass • ~1010.cm, <10nm, stable DC measurement • MRPC #2 (10-gap, pad readout, silicate glass) • >95%, <70 ps @ 1.4 kHz/cm2; ~90%, ~85 ps @ 25 kHz/cm2 • MRPC #3 (10-gap, strip readout, silicate glass) • ~97%, ~75 ps, <5mm • MRPC module for STAR-MTD • >95%, ~75 ps in cosmic-ray test; ~100%, ~70 ps in beam test • Low noise level • Good uniformity across the different strips and along the strip That’s all! Thank you! STAR MTD Workshop, USTC, Hefei, China

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