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Experimental features of strip-RPCs. Motivation FOPIs M ultistrip- M ultigap- RPC s Results Conclusions. Motivation. CBM ToF wall area ~ 100 m 2 100 modules with ~ 1 m 2 t <80 ps e > 95 % rate ~ 2 -20 kHz/cm 2 ~ 60000 channels.
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Experimental features of strip-RPCs • Motivation • FOPIs Multistrip-Multigap-RPCs • Results • Conclusions 10 - 13.03.2009
Motivation CBM ToF wall area ~ 100 m2100 moduleswith ~ 1 m2t<80 pse > 95 %rate ~ 2 -20 kHz/cm2~ 60000 channels Multi strip RPCs are one of the possibilities to fulfill the CBM-ToF requirements. The characteristical features of strip-RPCs can be determined with the FOPI Multistrip-Multigap-RPCs. 10 - 13.03.2009
Capacitor block Multi-strip anode Multi-pin connector MRPC glass stack Mounting table MMRPC design FOPIs MMRPC - parameters active area 90 x 4,6 cm strips 16 strip / gap 1.64 / 0.9 mm glass thickness 1 mm / 0.5 mm number of gaps 2 x 4 gap width 220 mm gas: Reclin/SF6/iso-But 80/15/5 10 - 13.03.2009
FOPI´s new ToF-barrel was used during the first Ni+Ni run in September 2007 FOPIs MMRPC barrel FEE 5 RPC Preamp. Disc. Elec. resol. FEE ~ 18 ps TAC ~ 10 ps t ~ 15 ps E < 25 ps Taquila 10 bit 12 bit QDC TAC free running common stop system at 40 MHz TAC ouput MMRPC Barrel characteristics: - 30 SM, 5 counters each with 16 strips - 4800 time + 2400 charge channels - active area 5.12 m2 - t<100 ps, e > 95 %, rate ~ 0,02kHz/cm2 QDC ouput input pulser 10 - 13.03.2009
t < 94 ps t d p p [GeV/c] K+ p+ v [cm/ns] MMRPC performance system time resolution T.I. Kang 10 - 13.03.2009
cluster Cluster size cluster = group of neighboring strips with signals generated by a single avalanche Cluster size drops at the edges- pure geometrical effect mean cluster size is 4.2 for the inner strips 11 mm 10 - 13.03.2009
minimum ionizing particles Cluster charge vs. bg correlation between mean cluster charge and energy deposition of the particle (Bethe-Bloch) mean cluster charge 10 - 13.03.2009
cathode ~5 mm ~ 5 mm strip: 1.64 mmgap: 0.6 mm anode strips Mean cluster charge - charge drops on the size strips - edge effects diminish the electrical field 10 - 13.03.2009
intrinsic time resolution intrinsic time resolution = time difference between hits in different strips for one cluster in the middle region of the rpc the intrinsic time resolution is about 30 ps electronic time res. The degradation towards the sides can be understood by the decreasing signal-to-noise ratio caused by the dropping pulse hight. 10 - 13.03.2009
cluster size dependence Same argumentation as in the slide before. more strips per cluster more charge and pulse hight better signal-to-noise ratio better intr. time resolution 10 - 13.03.2009
cluster size dependence charge per cluster grows linearly with the cluster size 10 - 13.03.2009
Conclusions • The FOPI MMRPC is ideal to study the characteristics of narrow strip counters. • - side effects are clearly identified build larger structures. • cross talk does not seem to be a problem (so far) • multihit analysis just started RPC development for CBM active area 20 x 16,5 cm strips 8 strip / gap 19.1 / 0.9 mm 4 strips are subdivided sub-strip / gap 1.6 / 0.9 mm glass type float glass thickness 0.5 mm number of gaps 2 x 4 gap width 220 mm FOPI type read out pickup electrode 10 - 13.03.2009
thank you People GSI – FOPI: Uni-HD: Korea University, K.Hildenbrand M.Ciobanu Seoul: T.I.Kang I.Deppner B.Hong Y.J.Kim N.Herrmann M.Kis P-A. Loizeau P.Koczon K.PiaseckiGSI-EE: Y.Leifels A.ReischlE.Badura M.Marquardt Y. Zhang R.Hardel W.Reisdorf K.Koch M.S.Ryu NIPNE Bucharest: N.Kurz A.Schüttauf M.Petrovici W.Ott J.Weinert V.Simion R.Schulze X.Zhang N.Zernezki 10 - 13.03.2009