1. Ingo DeppnerRPC 2012 Workshop, INFN, 05 - 10 Feb. 2012 1 A Mutistrip MRPC prototype for the CBM Time-of Flight wall Outline: Motivation / CBM-ToF Requirements Conceptional Design HD-MRPC design Experimental setup Results Summary / Next steps Ingo Deppner for the CBM-TOF Group Physikalisches Institut Uni. Heidelberg RPC 2012 – XI Workshop on Resistive Plate Chambers and Related Detectors

2. Ingo DeppnerRPC 2012 Workshop, INFN, 05 - 10 Feb. 2012 2 Motivation 80  120  1 ns RPC twisted pair cabe feed through gas box CBM-ToF Requirements  full system time resolution  T ~ 80 ps  Efficiency > 95 %  Rate capability  25 kHz/cm 2  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) Phase diagram of strongly interacting matter Compresed Barionic Matter Experimen at FAIR facility @ GSI bulk observables and rare probes Interaction rate 10 MHz

3. Ingo DeppnerRPC 2012 Workshop, INFN, 05 - 10 Feb. 2012 3 Conceptional Design Timing RPC with:  active area: A = 120 m 2  counter time resolution:  T ~ 50 ps  rate capability: R ~ 0.5 – 25 kHz/cm 2  granularity:  A ~ 6 – 50 cm 2  operation mode: free running (see talk of P.-A. Loizeau on Friday) Rate profile (Au-Au(minimum bias) at E=25 GeV/A) kHz/cm 2 A. Kiseleva, P.-A. Loizeau 44 SM (55%) have a rate < 1 kHz/cm 2

4. Ingo DeppnerRPC 2012 Workshop, INFN, 05 - 10 Feb. 2012 4 80  120  1 ns Conceptional Design 1,5 m 1,0 m RPC 1 RPC 2 RPC 3 RPC 4 RPC 5 RPC 6 1 Super Module

5. Ingo DeppnerRPC 2012 Workshop, INFN, 05 - 10 Feb. 2012 5 HD-MRPC design MMRPC fully symmetric and differential active area 32 x 27 cm 2 strips32 strip / gap 7 / 3 mm glass typefloat glass glass thickness0.5 mm number of gaps8 gap width 220  m pick-up electrode (green) Kapton foil (orange) HV electrode (blue) glass plates (light blue) HV electrode (blue) Kapton foil (orange) pick-up electrode (green) honeycomb st. connector to a wisted pair cable or to the preamplifier Electrode structure honeycomb st. side view front view side view 200 k  SMD resistor to ground transmission line with 2 x 50  imp- edance to ground connector to PADI impedance of 100  M4 plastic screw

6. Ingo DeppnerRPC 2012 Workshop, INFN, 05 - 10 Feb. 2012 6 HD-MRPC design Pickup electrode HV electrode PADI connected directly to the RPC mounting in clean room @GSI RPC side view RPC in gas tight aluminum box

7. Ingo DeppnerRPC 2012 Workshop, INFN, 05 - 10 Feb. 2012 7 Technical properties Signal rise time measurement Reflectometer measurement 0 200400600 rise time [ps] 2 ns RPC twisted pair cabe non twisted part connector feed through gas box Impedance about 93  mean rise time 208 ps

8. Ingo DeppnerRPC 2012 Workshop, INFN, 05 - 10 Feb. 2012 8 Experimental setup Test beam time @ COSY accelerator Jülich, Germany in Nov. 2011 with protons of 2,5 GeV Heidelberg RPC 4 front PMTs 2 back PMTs 2 RPCs from Tsinghua Univ., China 3 RPCs from NIPNE Romania 2 RPCs from HZDR Germany Hodoscope warmed-up backplane beam Beam profile extracted from Hodoscope is used for rate estimation beam area about 0,4 cm 2 vertical scintillator horizontal scintillator

9. Ingo DeppnerRPC 2012 Workshop, INFN, 05 - 10 Feb. 2012 9 Results 95% HV = 11.5 kV Thr. = 30 mV HV = 11.3 kV rate < 500 Hz/cm 2 directly connected preamps allow for lowering the threshold by  5 mV

10. Ingo DeppnerRPC 2012 Workshop, INFN, 05 - 10 Feb. 2012 10 Results Mean cluster size is defined as the average number of neighboring strips firing simultaneously HV = 11.5 kV Thr. = 30 mV HV = 11.5 kV Thr. = 30 mV

11. Ingo DeppnerRPC 2012 Workshop, INFN, 05 - 10 Feb. 2012 11 Results dt = t Buc-RPC – t HD-RPC dt [channel] counts dt spectrum  t = 71.5 ps Considering equal time resolution for both MRPC‘s the time resolution for the individual RPC is about 51 ps

12. Ingo DeppnerRPC 2012 Workshop, INFN, 05 - 10 Feb. 2012 12 Summary  At the Physikalisches Institute of the Heidelberg University we developed a MMRPC prototype for the low rate region (below 1 kHz/m 2 ) for CBM  This prototype was successfully tested with pions and protons at SIS18 at GSI / Darmstadt and at the COSY accelerator in Jülich  Based on these in-beam tests we can show that an efficiency above 95% was reached for preamplifier thresholds below 30 mV  Results obtained from the electronics mounted directly on the RPC indicate a higher stability in terms of noise and signal reflections  Warming up the RPC environment by 15 °C seems to be enough in order to fulfill the CBM - TOF requirement of he outer region  The mean cluster size for this prototype is in the order of 1.3 and growing with temperature  Time resolution is in the order of 50 ps

13. Ingo DeppnerRPC 2012 Workshop, INFN, 05 - 10 Feb. 2012 13 Next steps Full size demonstrator RPC fully differential active area 52 x 54 cm 2 PCB size 56 x 60 cm 2 (maximal size) strips52 strip / gap 7 / 3 mm glass typefloat glass glass thickness0.5 mm number of gaps8 - 9 gap width 220  m PADI board with 4 channel input (under developmet) transmission line with 2 x 50  imp- edance to ground connector to a 4 ch. PADI 5 cm 200 k  SMD resistor to ground 5 cm Super module # RPCs: 6 # strips: 312 # PADI (4 ch.) : 156 # channels: 624 total active area: 152 cm x 104 cm overlap h: 4 cm v: 2 cm box size (inside) 170 cm x 130 cm x 14 cm

14. Ingo DeppnerRPC 2012 Workshop, INFN, 05 - 10 Feb. 2012 14 Contributing institutions: Tsinghua Beijing, NIPNE Bucharest, GSI Darmstadt, USTC Hefei, PI Heidelberg, KIP Heidelberg, INR Moscow, ITEP Moscow, IHEP Protvino, HZDR Rossendorf, KU Seoul, CCNUWuhan RBI Zagreb. thank you for your attention Special thanks goes to: Norbert Herrmann, Jochen Frühauf, Pierre Alain Loizeau, Changzhou Xiang

15. Ingo DeppnerRPC 2012 Workshop, INFN, 05 - 10 Feb. 2012 15 CBM Physics topics  Deconfinement / phase transition at high ρ B  QCD critical endpoint  The equation-of-state at high ρ B  chiral symmetry restoration at high ρ B Observables  excitation function and flow of strangeness and charm  collective flow of hadrons  particle production at threshold energies  excitation function of event-by-event fluctuations  excitation function of low-mass lepton pairs  in-medium modifications of hadrons (ρ,ω,φ → e+e-(µ+µ-), D) In order to measure all these observables with an high accuracy, we need a good particle identification Backup non twisted part connector  p K D. Kresan Au + Au @ 25GeV Kaon acceptance depends critically on TOF resolution

16. Ingo DeppnerRPC 2012 Workshop, INFN, 05 - 10 Feb. 2012 16 Backup 2 ns Cross talk measurement with a reflectometer

17. Ingo DeppnerRPC 2012 Workshop, INFN, 05 - 10 Feb. 2012 17 Backup

18. Ingo DeppnerRPC 2012 Workshop, INFN, 05 - 10 Feb. 2012 18 Backup 80  1 ns