cbm-meeting, darmstadt26-29.02.2008 a.schüttauf for the fopi- collaboration fopis new mmrpc-barrel

CBM-Meeting, Darmstadt 26-29.02.2008

A.Schüttauf for the FOPI-collaboration

FOPIs new MMRPC-

barrel


Outlook

The MMRPC parameters Installation of the RPC-barrel First experiment using the barrel Results and system performance Summary and Outlook


FOPI ToF Upgrade (Reminder)

For high granularities experiments price isan issue.

FOPI TOF: Size ~5 m2

Channels ~ 4800 ToF<100 ps <0.5 cm

Central Au-Au collisionat 1.45 AGeV has ~60-particles in the acceptanceof the proposed RPC barrelThis needs a granularity of700 cells (2500 strips)


MMRPCs production parameters

FOPIs MMRPC parameters:90 x 4.6 cm2 active area1.1 & 0.5 mm 10 glass plates8 x 220 µm gaps (fishing rope)16 strips 1.64/0.9 mm strip/gap~9.5 kV applied voltageGas:C2F4H2/isobutane/SF6 80/5/15

Multi-pin connector Multi-strip anode

Capacitor block

Glass stack 8 gaps

Stesalit support Mounting table

MMRPC glass stack


FOPIs Super Module (SM)

5 MMRPC in a Super Module (SM)30 SMs within FOPI

Gas box

HV-connector

Gas in/outlets

End-flange

1 MMRPC

Interface between MMRPC & ElectronicsSAMTEC 50 Ω multi-coaxial cable0.8 mm pitch. In total 80 connections (16 used).


Full Readout System

FEE5 + TAC/QDC-Digitizer 16 ch.G ~ 160 TAC ~10 ps/chf ~ 1.5 GHz Zero-suppressionPF ~ 0.56 W/ch PT ~ 0.5 W/ch

Full system electronic resolution E < 25 ps

Free running common stop system at 40 MHz.Individual TAC resets 0.033-2.0 µs.

Electronic resolution

FEE ~ 18 ps TAC ~ 10 ps t ~ 15 ps

TAC < 2 ps+ FEE < 3 ps+ Card 10 ps + Clock 10 ps t ~ 15 ps

M.Ciobanu, K.Koch


Final signal shape for the MMRPC

Primary RPC signal

• The primary charge for a RPC-strip signal is 40-100 fC which is in our case between 1-7 mV.

• The optimal adaption to 50 Ω leads to a nearly perfect primary signal shape.

• After amplification (G~160) the signal has a threshold due to rest oscillations from the discriminator of Uthr>80 mV

Amplified RPC signal


MMRPC: Housing & Joining

Building Super Module 0December 2005

K.D.HildenbrandM.KisX.ZhangY.J.Kim


Setup for in beam tests with SM0

Front ViewTop View

Trigger PMT1 & PMT2 Efficiency PMT1 & PMT2 & PMT3

Side View

PMT 2 PMT 1

PMT 3

RPCs

RPCs

PMT 1PMT 2

PMT 3

Beam , p, d

Measurements:Timing, efficiency & cluster sizeRate dependence of float glass MRPCs


Timing and efficiency for SM0:RPC versus PMT system

Our first module (SM0) deliveredfor E-Fields > 107 kV/cm the following results:

Rate 80-150 Hz/cm2

RPCb + Start σt< 96 psStart σts< 78 ps

RPC σRPC< 56 ps Efficiency > 99 %


Timing and efficiency for SM0:RPC (b) versus RPC (d)


Rate 80-150 Hz/cm2

RPCb + RPCd σt< 84 ps

RPCbd \√2 σRPC< 59 ps Efficiency > 99 %

It confirms the RPC versus PMT measurement within the errors. Both show consistently a time resolution σRPC< 60 ps.


Timing and Efficiency for SM0:At high rates 3-5 kHz/cm2


Rate 3-5kHz/cm2

RPCb + Start σt< 135 psStart σts< 78 ps

RPC σRPC< 110 ps Efficiency > 75 %

T.I Kang

FOPI needs a rate capability between 10-50 Hz/cm2.


Cluster size and charge for SM0

<nstr> =: Mean number of strips fired for a particle.

RMS(nstr) =: Width of the cluster distribution.

The cluster size is smaller then 2.5 strips (<nstr>) with a width below 1.5 strips (RMS(nstr)).

<Q> =: Mean charge for a stripRMS(Q) =: Width of the charge

distribution

The mean cluster charge and its RMS is nearly linear depended on the electric field.


Production of 30 SMs in 2006

All SMs under permanent Ar gas flow

All 30 SMs were tested up to 13 kV.In the final measurement regime, between100-110 kV/cm (8.8-9.6 kV) , all SM were below 0.4 Hz/cm2.

Rat

e H

z/cm

2E-Field (kV/cm)

0.3 Hz/cm2 0.3 Hz/cm2


FOPIs new ToF-barrel was used during the first Ni+Ni run in Sepember 2007


Timing and position resolution for the full system

After all corrections the Time of Flight resolution isσToF < 95 ps including the start resolution with σStart < 65-70 ps

The final -resolution is Δ < 0.14o

which is Δx < 2.5 mm.


Cluster size in relation to the energy loss of the particle

With the Pt cut we select similarangles for the traversing particle in the RPC. The dE/dx is measured by the CDC independently.

The RPCs shows a strong cluster size (<nstr>) dependence on the dE/dx. Varying from<nstr> ~ 2.5 for MIP like particles up to <nstr> ~ 4.3 for slow particleswith high dE/dx.

For a high Pt and low primary dE/dxWe see the expected behavior of <nstr> ~2.5

Plotting the mean summed RPC charge versus the CDCdE/dx, we see a strong correlation between bothmeasurements.


Avalanche size in relation to primary charge and gap thickness

Gap size variation Primary charge variation


The final PID performance:

v [cm/ns]

p [

GeV

/c]

pdt

+

-

K+

K-

K.Piasecki

K- - PID: S/B > 10

K-


How to improve ? Gas mixture

Timing:t = 1.28255/(-)v - = Effective Townsend coefficient v = Drift velocity I.Deppner


GSI-FOPI :K.HildenbrandT.I.KangY.J.Kim M.KisP.KoczonY.LeifelsM.MarquardtW.ReisdorfM.S.RyuA.SchüttaufJ.WeinertX.ZhangN.Zernezki

GSI-EEE.BaduraR.HardelK.KochN.KurzW.OttR.Schulze

HD-UniversityM.CiobanuI.DeppnerA.ReischlK.PiasetzkiN.Herrmann

NIPNE, Bucharest M.PetroviciV.Simion

People:

Summary:

• Our final electronic resolution is E<25 ps for the final system.

• R&DTiming SM0:A) Single hits MMRPC t<48 ps

(RPC) B) Single hits MMRPC t<55 ps

(RPC+E.) C) Single hits MMRPC t<85 ps

(Full) • Efficiency:

A) Single hits > 99%

• Full system performance (2200 strips):• Timing

A) Single hits MMRPC t<60 ps (RPC)

B) Single hits MMRPC t<65 ps (RPC+E.)

C) Single hits MMRPC t<95 ps (Full)

• Efficiency:A) Single hits > 95%

• Cluster size:Is bigger than expected <nstr> ~ 2.5-4.0

and depending on the dE/dx of the particle. It’s <nstr> ~2-2.5 for MIPs.

• PID: K- pid is possible with a S/B =10/1

Korea University,SeoulB.Hong

Conclusion:

FOPI successfully commissioned the new MMRPC-barrel which can now be usedfor the anticipated physics program.


Future developments at the GSI/FAIR

facility for the CBM-ToF

1 10 100 10001

10

100

PADI #1 ,#2 and TACQUILA3, at differents VthrOne channel Timing Resolution

Sig

ma

[ps]

Uinp [mV]

#1;198 mV 98 mV 66 mV #2;198 mV 98 mV 66 mV

M.CiobanuM.KisA.Schuettauf

An ASIC based Preamplifier Discriminator(PADI) for the CBM-TOF system


ToF, dE/dx, Kaon iD


Q/A: -tests for all SM

Test setup for gamma-ray test

High voltage: 9.5 kVGas flow : 2-3 daysHit rate: 50-70 Hz/counterTiming resolution: σTOF< 150-250 ps

The results of SM17 for the gamma


Q/A: Dark-rate measurements

E-Field kV/cm

Rat

e H

z/cm

2

E-Field kV/cm

Rat

e H

z/cm

2

X.Zhang


Signal


Final SM for the installation into FOPI

9.5 kV


Multi-strip-MRPC (MMRPC)


dE/dx dependence of RPCs


DI

Tout+

Tout-

THR-

Threshold Voltage

THR+

Input+

Input-

Hys

Hyssteresis En/Dis

PA

Buffer

Eout+

Eout-

Bias

Iext

+1.8V

RextRext -

Rext

VSSVDD

0V

Bias Tout

+

Ch 1 - 4 Ch 1 - 4

Ch 1 - 4

cbm-meeting, darmstadt26-29.02.2008 a.schüttauf for the fopi- collaboration fopis new mmrpc-barrel

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