cbm collaboration meeting, gsi 10 - 13.03.2009 experimental features of strip-rpcs motivation fopis...
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CBM Collaboration Meeting, GSI
10 - 13.03.2009
Experimental features of strip-RPCs
• Motivation• FOPIs Multistrip-Multigap-RPCs• Results• Conclusions
CBM Collaboration Meeting, GSI
10 - 13.03.2009
Motivation
CBM ToF wall
area ~ 100 m2
100 moduleswith ~ 1 m2
t<80 ps > 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.
CBM Collaboration Meeting, GSI
10 - 13.03.2009
MMRPC design
Multi-pin connector Multi-strip anode
Capacitor block
FOPIs MMRPC - parametersactive area 90 x 4,6 cmstrips 16strip / gap 1.64 / 0.9 mmglass thickness 1 mm / 0.5 mmnumber of gaps 2 x 4gap width 220 m
gas: Reclin/SF6/iso-But 80/15/5
Mounting table
MRPC glass stack
CBM Collaboration Meeting, GSI
10 - 13.03.2009
FOPIs MMRPC barrel
FOPI´s new ToF-barrel was used during the first Ni+Ni run in September 2007
MMRPC Barrel characteristics:- 30 SM, 5 counters each with 16 strips- 4800 time + 2400 charge channels- active area 5.12 m2
- t<100 ps, > 95 %, rate ~ 0,02 kHz/cm2
RPC Preamp. Disc.
QDC TAC
FEE 5
Taquila
input
pulser
QDC ouput
TAC ouput
Elec. resol.
FEE ~ 18 ps TAC ~ 10 ps t ~ 15 ps
E < 25 ps
10 bit 12 bit
free running common stop system at 40 MHz
CBM Collaboration Meeting, GSI
10 - 13.03.2009
MMRPC performance
t < 94 ps
v [cm/ns]
p [
GeV
/c]
pK+
+
dt
T.I. Kangsystem time resolution
CBM Collaboration Meeting, GSI
10 - 13.03.2009
Cluster size
Cluster size drops at the edges- pure geometrical effect
mean cluster size is 4.2 for the inner strips
cluster
cluster = group of neighboring strips with signals generated by a single avalanche
11 mm
CBM Collaboration Meeting, GSI
10 - 13.03.2009
Cluster charge vs.
minimum ionizing particles
correlation between mean cluster charge and energy deposition of the particle (Bethe-Bloch)
mean cluster charge
CBM Collaboration Meeting, GSI
10 - 13.03.2009
Mean cluster charge
- charge drops on the size strips
- edge effects diminish the electrical field
cathode
anode strips
~5 mm
~ 5 mm strip: 1.64 mmgap: 0.6 mm
CBM Collaboration Meeting, GSI
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.
CBM Collaboration Meeting, GSI
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
CBM Collaboration Meeting, GSI
10 - 13.03.2009
cluster size dependence
charge per cluster grows linearly with the cluster size
CBM Collaboration Meeting, GSI
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
pickup electrode
RPC development for CBMactive area 20 x 16,5 cmstrips 8strip / gap 19.1 / 0.9 mm4 strips are subdivided sub-strip / gap 1.6 / 0.9 mmglass type floatglass thickness 0.5 mmnumber of gaps 2 x 4gap width 220 mFOPI type read out
CBM Collaboration Meeting, GSI
10 - 13.03.2009
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. LoizeauP.Koczon K.Piasecki GSI-EE:Y.Leifels A.Reischl E.BaduraM.Marquardt Y. Zhang R.HardelW.Reisdorf K.KochM.S.Ryu NIPNE Bucharest: N.KurzA.Schüttauf M.Petrovici W.OttJ.Weinert V.Simion R.SchulzeX.ZhangN.Zernezki
thank you