1. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 1 Status of high rate MRPC for CBM-TOF Outline: Introduction of CBM-TOF Development and aging test of low resistive glass Development and aging test of high rate MRPC Design and beam test of real-size prototype Production preparation Summary Wang Yi Department of Engineering Physics, Tsinghua University

2. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 2 Rate profile (Au-Au(minimum bias) at E=25 GeV/A) A. Kiseleva, P.-A. Loizeau A B C D The structure of CBM-TOF wall Timing RPC with:  active area: A = 120 m 2  intrinsic time resolution:  T ~ 50 ps  rate capability: R ~ 0.5 – 25 kHz/cm 2  granularity:  A ~ 4 – 30 cm 2  operation mode: free running D: 8kHz/cm 2 – 25kHz/cm 2 C: 3.5kHz/cm 2 – 8kHz/cm 2 B: 1.5kHz/cm 2 – 3.5kHz/cm 2 A: 0.5kHz/cm 2 – 1.5kHz/cm 2

3. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 33 Voltage drop changes with rate: Two main ways to improve rate capability: Reducing bulky resistivity of electrode glass (CBM) Reducing the avalanche charge (ATLAS) Other methods: Reducing the thickness of glass Warming the detector How to increase rate of MRPC Wang Yi. Chinese Physics C. 33(5): 374-377. 2009 Wang Jingbo. Nucl. Instru Meth.A713(2013): 40-51

4. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 444 Components: SiO2, Fe 2 O 3, Na 2 O,AL 2 O 3, MnO 2 Development of low resistivity glass Melting Cooling Cutting Polishing Glass resistivity: ~10 10  cm  Different compositions and related production procedures have been studied, yielding a tunable bulk resistivity in the range of 10 10 –10 11 Ωcm.  In the mass production, in order to produce reliable glasses with high quality, surface measurement has been taken as a key part of the quality control.  This glass shows a large stability against electrical stress. Process:

5. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 55 Performance of low resistivity glass 32cm x 30cm

6. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 66 Performance of low resistivity glass Resistivity vs. HV Resistivity at different temperature 10 Wang Jingbo. Nucl. Instru. Meth. A621(2010): 151-156 Zhu Weiping. Science China, Technological Sciences, 2013, 56(11) 2821-2826

7. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 7 Aging test of glass This glass was applied with 1000V for about 32days, integrated charge: 1 C/cm 2 --roughly corresponding to the CBM life- time over 5 years operation at the maximum particle rate. Glass specifications:

8. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 8 Irradiated by fast neutrons Neutron test by Rossendorf group, 2014 Cyclotron U-120M (Řež) Proton energy 36 MeV Neutron production target Be Neutron flux 10 8 - 10 10 n/cm 2 /s Neutron energy spectra 1 – 36 MeV

9. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 9 Comparasion with other material Morales talk @RPC2012

10. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 10 GSI Apr/Agu 2009 Cosy 2011 HZDR 2011/2012 2-pad MRPC 3-strip MRPC 12-pad MRPC 8-strip MRPC Development of high rate MRPC

11. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 11 Rate: 70kHz/cm 2 Time resolution: 40 ps Test results in different labs Even though the rate is 70kHz/cm 2, the efficiency is still higher than 90% and the time resolution is about 80ps. Test results at Nuclotron, Dubna

12. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 12 Strip MRPC is aimed outer area. Glass: glass thickness 0.35mm and 0.7mm, 4.5 x 10 12 Ω.cm Strip: 2.2cm x 12.5cm, 3mm interval, 8 strips Gas gap: 10 x 0.25mm Beam test @Dubna, 2013 Source: 1.5GeV Deuterium. 2-3s/spill Trigger: S2 & SFFD & S3 & S4, 7cm*7cm Mission: 1 March 10 th -12 th, calibrate DCs, HV scan, efficiency and time resolution 2 FEE: Ninos 3 TDC: HPTDC Structure of thin glass MRPC

13. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 13 Performance of strip MRPC-common glass Cluster size Efficiency and time resolution Zhu Weiping. Nucl. Instru. Meth. A735(2014): 277-282 Zhu Weiping. JINST 9 C07007, 2014

14. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 14 Performance of strip MRPC-common glass It can be seen the thinner the glass, the higher of the rate. For the 0.35mm common glass, the rate of MRPC can reach 3kHz/cm 2, which can be used in the outer region of the wall.

15. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 15 Hign rate MRPC X-ray Generator 130cm 60cm This is online test system. The efficiency and time resolution can be obtained by cosmic ray while irradiated by X-rays. 0.1C/cm 2 charge is accumulated in 35 days. Aging test of high rate MRPC

16. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 16 By monitoring the performance on line, we can grasp the detector condition simultaneously. Performance & Dosage

17. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 17 ~500 events/5days More events ->Better statistics Efficiency and time resolution Wang Yi. JINST 7 P11017, 2012

18. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 18 Gas out let HV Signal transmission Interface board PMMA Gas box Normal MRPC Gas out let HV Signal transmission Interface board Gas in let Self-sealed MRPC Gas pollution under high flux rate ---Sealing technology Two MRPC were designed. Same dimension: 50cm x 50cm Gas gap:4x2, 0.25mm Upper: normal MRPC, using aluminium box Lower: Sealed MRPC Compare the gas exchange efficiency 81 litre 2.5 litre

19. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 19 MRPC HV: 5500V Gas flow: 54-3-3(ml/min) X-ray energy: 60kV~160kV X-ray during time: 2min Dose rate estimate: D = 1700V 2.65 Q t r / s Sealed MRPC Normal MRPC 60kV7494 70kV7597 80kV80103 90kV86108 100kV95112 110kV103118 120kV108123 130kV116130 140kV120138 150kV128144 160kV135151 Restoration speed vs. radiation strength

20. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 20 Restoration speed vs. gas flush rate 20 t r / s60sccm40sccm20sccm10sccm 80kV103111117138 90kV108116131159 100kV112122147176 110kV118137160205 t r / s60sccm40sccm20sccm10sccm 70kV75768695 80kV808295105 90kV8695106118 Normal MRPCSealed MRPC

21. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University Dimension: 1800 x 280 x120, PADIs are on the back of SM, Can be connected to main frame by screw directly. Design of inner wall based on pad-MRPC

22. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 22 Pad Readout MRPC Structure 22 Glass: 0.7mm, 5.2cm x 19.5cm Pad: 2cm x 2cm, 16pads Gas gap: 10 x 0.22mm

23. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 23 Feature Module EfficiencyTime resolutionDark rateCluster size MRPC_198.4%56.2 ps0.57 Hz/cm 2 1.23 MRPC_298.6%58.7 ps0.53 Hz/cm 2 1.30 MRPC_398.2%63.3 ps0.61 Hz/cm 2 1.27 MRPC_498.4%62.0 ps0.55 Hz/cm 2 1.25 HV: 6.0kV The reference time is about 62ps (2.48x25ps ). Cosmic test of pad-MRPC

24. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 24 Size of the gas box: 130mm x 290mm x 330mm Designed for PADI 8 Super module of pad-MRPC

25. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 25 Compare with strip-design ItemPadStrip Glass size195 x 52 x 0.7350 x 100 x 0.7 350 x 200 x 0.7 Number of different counters 12 Number of modules328 Number of counters1240252 Number of signals2976040320 Impendence mismatchNo reflectionSignal reflection Cluster size 2.5 （ 2.5 signal) 2.5 (5 signal) Spatial resolution<6mm Occupancy<4%~10%

26. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 26 Glass: low resistive glass 0.7mm thick, 27cm x 25cm Strip: 27cm x 0.7cm, 0.3cm interval, 24 strips Gas gap: 8 x 0.25mm, two stacks Gas box: 600mm x 500mm x 72mm Design of strip-MRPC Differential strip: 7mm wide+3mm interval h w t ground Feed trough: Micro-strip, 50 Ω

27. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 27 Layout of middle TOF wall

28. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 28 Experimental Setup: BEAM Buc-2013 THU-Pad Buc-Ref PMT HD-Ref Beam time in October 2014 at GSI 1.1 GeV 152 Sm beam On 0.3mm/4mm/5mm Pb target Flux rate several hundreds Hz/cm 2 THU-Strip HD-P2 BEAM Beam test @GSI, Oct.2014

29. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 29 Analyzed set of data File nameHV (kV)PADI threshold (mV) Sun13505.5170 Sun13205.5180 Sun12405.5190 Sun12055.5200 Sun01255.8180 Sun02365.6180 Sun03365.5180 Sun04355.4180 Sun05255.2180 Sun06245.0180 All files calibrated with: TofTdcCalibHistos_Sat11Late.root good

30. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 30 High rate test in February 2015 at SPS CERN 13 GeV Ar beam Flux rate around 1kHz/cm 2 Buc-2013 THU-Pad Buc-Ref PMT HD-Ref THU-Strip HD-P2 Experimental Setup: BEAM USTC Up setting Down setting Beam test @ SPS Feb 2015

31. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 31 The data analysis is based on CBM ROOT, macro developed by TOF Group. Analysis Procedure: 3 Main Steps. 1 Unpacking 2 Cluster Building 3 Analysis Converting LMD files into unpacked ROOT file, containing timing, TOT, super module type, super module, RPC, strip, side information of each hit. Initial calibration: Align center of each strip in Detector Under Test and Reference Detector. Iterative calibration: Calibrate data in time-walk, gain and velocity correction. Build calibrated hits into clusters. Calculating observables from fully calibrated hits include clustersize, time resolution and efficiency. Data analysis method

32. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 32 1.Time-walk correction 2.Gain correction Fast time signals can be gotten from large. leading to a dependence of measured time and amplitude of the analogue signal. Amplification gain of PADI varies between each channel, which should be corrected out to get initial amplitude for time- walk correction. Analysis steps (1)

33. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 33 3.Strip alignment correction4.Velocity correction Different cable length and electronic delay lead to the shifting of calculated center of different strip, influencing the position of hits. Slower particles need a longer time to cross the distance between Dut and Mref, widen the time difference distribution. Analysis steps (2)

34. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 34 Results: GSI Oct. 2014 Run: Sun1205 – 5500V: Analysis Process Before Calibration After Calibration Time-walk correction Velocity correction

35. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 35 Run: Sun1205 – 5500V Time Resolution ThresholdEfficiencyTime ResolutionCluster Size 170mV97.0%71.6ps1.7 180mV97.0%68.9ps1.7 190mV97.0%71.0ps1.6 200mV96.7%68.9ps1.6 Analysis Result under Different Threshold Efficiency: Around 97% Time resolution: Around 70ps Results: GSI Oct. 2014

36. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 36 February resolution higher than October, probably two reasons: Flux rate is higher. Diamond is eliminated from the analysis, distance between Dut/Mref and Bref is closer, and velocity correction can’t be effective enough. Feb 2015 Oct 2014 Tracking Developed by Nobert Herrmann Correct efficiency and calibrate time and space for hits in Dut. Tracking setup: tofFindTracks->SetMinNofHits(2); tofFindTracks->SetNStations(3); tofFindTracks->SetStations(374); Results: SPS Feb. 2015

37. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 37 Rate information: Results under different flux rate: Flux rate at THU Strip counter: around 1kHz/cm 2 Run nameRateEfficiencyResolutionCluster 01Mar1126 20098.3%87.2ps1.6 03Mar0607 30097.5%82.4ps1.6 03Mar0646 60097.3%79.1ps1.6 04Mar0425 90098.4%84.9ps1.6 Efficiency: Around 98% Two runs of less events Results: SPS Feb. 2015

38. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 38 Double StackSingle StackSealing Numberx1 Gas gap number2X48 Gas gap width0.25mm0.22mm0.25mm PCB dimension360mm X 338mm 360mm X 332mm 360mm X 338mm Glass dimension276mm X 330mm Strip length270mm Strip width7mm + 3mm Strip number32 Detection area270mm X 317mm New MRPC for SPS Nov. 2015

39. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 39 Glass mass production Continuous melting Continuous pouring Continuous annealing Web: www.ykglass.net All of the low resistive glass will be produced at Yakang glass.

40. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 40 Material preparation Continuous melting Continuous pouring Continuous annealing Cutting Grinding and polish Production schedule 2015.8—2016.3 2015.12 glass samples for measurement and prototype. 2016.1—2016.12 Glass yield: >100m 2 /month

41. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 41 Summary 1.The resistivity of low resistive glass is around ~10 10 .cm, and rate capability of high rate MRPC can reach 70kHz/cm 2. This technology can be used to construct CBM-TOF wall. 2.The rate capability of MRPC assembled with 0.35mm glass can reach 3kHz/cm 2. It can be used in the outer region of CBM-TOF wall. 3.The aging test of low resistive glass and high rate MRPC have been done. 4.The performance of real-size prototype is excellent. Efficiency reach 97% and time resolution is around 45ps. 5.Preparation of SPS beam test (2015.11) and counter production goes smoothly.

42. Workshop on STAR upgrade. Sep.21-22 th, 2015, USTC, Hefei Wang Yi, Tsinghua University 42 Thanks for your attention !