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A differential MRPC prototype for CBM

A differential MRPC prototype for CBM. Ingo Deppner for the CBM-TOF Group Physikalische Institut Uni. Heidelberg. Outline: Motivation and CBM-ToF Requirements Conceptional Design of CBM-ToF MRPC Design Experimental Setup (@ COSY) Results Summary. Motivation.

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A differential MRPC prototype for CBM

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  1. A differential MRPC prototype for CBM Ingo Deppner for the CBM-TOF Group Physikalische Institut Uni. Heidelberg • Outline: • Motivation and CBM-ToF Requirements • Conceptional Design of CBM-ToF • MRPC Design • Experimental Setup (@ COSY) • Results • Summary Ingo Deppner

  2. Motivation Kaon acceptance depends critically on TOF resolution CBM-ToF Requirements • full system time resolution sT ~ 80 ps • Efficiency > 95 % • Rate capability  25 kHz/cm2 • Acceptable cross-talk and charge-sharing. • Polar angular range 2.5° – 25° • Low power electronics (~75.000 channels). • Pile-up < 5% • Occupancy < 5 % (for Au-Au(central) at E=25 GeV/A) Ingo Deppner

  3. Conceptional Design Timing RPC with: • active area: A = 120 m2 • counter time resolution: sT ~ 50 ps • rate capability: R ~ 0.5 – 25 kHz/cm2 • granularity: DA ~ 6 – 50 cm2 • operation mode: free running HK55.3 Rate profile (Au-Au(minimum bias) at E=25 GeV/A) 44 SM (55%) have a rate < 1 kHz/cm2 kHz/cm2 A. Kiseleva, P.-A. Loizeau Ingo Deppner

  4. Strip-MRPC Design Fully differential Strip MRPC developed at Physikalische Institut Uni. Heidelberg RPC in aluminum box active area 28 x 16.5 cm2 strips 16 strip / gap 7 / 3 mm glass thickness 0.55 mm float number of gaps 8 gap width 220 mm gas: Reclin/SF6/iso-But 85/10/5 FEE (PADI III) pickup electrode Counter is designed for an impedance of 100 Wstrip size ~ avalanche size Ingo Deppner

  5. proton – beam Buc. – MRPC 1st. Sili.stage 2nd. Sili.stage HD- RPC 1st. Scin. + PMT 1,2 2nd. Scin. + PMT 3,4 rear view 3rd. Scin. + PMT 5,6 front view Experimental Setup test beam time @ COSY Jülich in Nov. 2010 Beam parameter: Beam: protons Momentum: 3 GeV/c Extraction time: 5 min Rate: 10 Hz/cm2 – 40 kHz/cm2 Beam diameter:  6 cm Trigger and DAQ: TDC: CAEN 1290V Ingo Deppner

  6. Results cluster := group of neighboring strips with signals generated by a single avalanche A proper threshold is important for a low occupancy Ingo Deppner

  7. Results 2RPC := 2sys – (ref/2)2 ref = 0.5*( 4 PMT_i )1/2 At this time resolution level the TDC non-linearity corrections become important Ingo Deppner

  8. Results At a higher threshold bigger signals with steeper rise times are discriminated which leads typically to a better time resolution Ingo Deppner

  9. hits in the RPChits in the trigger PMTs Efficiency := Results Control of threshold is very important for a high and uniform efficiency Ingo Deppner

  10. Results Ingo Deppner

  11. Summary Summary • With a threshold of 30 mV at nominal working voltage (11.7 kV) an efficiency of about 94 % is obtained • Cluster size is between 1.4 (thr. = 50 mV) and 1.6 (thr. = 30 mV) at nominal working voltage  occupancy can be reduced by setting the proper threshold • Cross talk is less 3 % • Time resolution is in the order of 50 ps and depends also on threshold • A rate capability of 1 kHz/cm2 is not achievable with this prototype (float glass)  warming up the counter can help fulfilling this criterion Next steps • testing the rate capability of this prototype in a high rate environment at GSI in a warm up condition • building and testing a full size prototype (active area 25 x 32 cm2, 32 channels and semi conducive glass) until end of May • next iteration of PADI (V) with individual threshold settings is ready in the next month Ingo Deppner

  12. CBM-TOF Group Contributing institutions: Tsinghua Beijing, NIPNE Bucharest, GSI Darmstadt, USTC Hefei, PI Heidelberg, KIP Heidelberg, INR Moscow, ITEP Moscow, IHEP Protvino, FZD Rossendorf, KU Seoul, RBI Zagreb. thank you for your attention Ingo Deppner

  13. Backup Typical RPC signal at  11 kV(from one pickup electrode) reflectometer measurements Scope: LeCroy Wavepro 7300, 3 GHz, 10GS/s • signal properties: • amplitude 5 – 30 mV • rise time ~ 250 ps • FWHM ~ 500 ps – 1 ns Ingo Deppner

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