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