RPC R&D status in Bucharest(JRA12-I3HP)

Mihai Petrovici - CBM-Meeting, GSI, March 1,2006

• Short history

• SMSMGRPC – Glaverbel Glass Prototype– Construction Details

– 60Co Source Test

– In-Beam Test

• Pestov glass Prototype

• Differential read-out Prototype

• Conclusions

First tests – 60Co source - early 2000

= 93 ps

= 90 ps

30 cm length prototype

90 cm length prototype

= 125 ps

Plastic scintillator

FEEFTA420

FEE FTA810

Readout electrode:

- support:0.3mm thick pcb plate

- 16 golded strips on each side

- pitch: 2.54 mm, 1.00 mm strip width,1.54 mm gap width

In-Beam Tests – 2001

•The dark rate increases from 3.6 Hz/cm2 @ 5.8 kV to 6Hz/cm2 @ 7 kV.

•For HV > 6.2 kV the efficiency is larger than 95 %.

•The time resolution improves from ~ 90 ps @ 5.8 kV to 67 ps @ 7 kV.

•The average charge grows almost exponential as a function of HV

FEECascaded DBAs

Signal Amplification

DBA - low gain the charge distribution doesn’t show a clear separation from the noise

DBA + DBA a much better separation of the charge distribution from the noise maximum in the efficiency

CBM extra requirements:

• High granularity

• High counting rate

• Aging

SMSMGRPC – Glaverbel Glass Prototype

● SMSMGRPC with float glass electrodes keeps the performances

up to ~1 kHz/cm2 ( glass ~ 1012 cm)

● ToF – CBM subdetector – high counting rate environment, up to

20 kHz/cm2

● Solutions:

– Glass electrodes with lower resistivity

– Smaller and many gaps

● Our prototype was built using glaverbel glass with

~1010 cm as it was specified by the company !!!

Electrode sequence:

- 1.1 mm glass covered by copper foil

- 0.3 nylon fishing line

- 1.1 mm glass plate (supporting the

spacers)

- 0.3 mm nylon fishing line

- 1.1 mm glass plate

- 0.3 mm double sided strip readout plate

symmetry plane

Readout electrode:

- support:0.3mm thick pcb plate

- 16 golded strips on each side

- pitch: 2.54 mm, 1.00 mm strip width,

1.54 mm gap width

Sizes:

glass electrodes: 46 x 900 mm2

readout plate: 0.3 x 46 x 980 mm3

housing: 40 x 80 x 960 mm3 Al box

Construction Details

60Co Source Test

= 98 ps

85% C2F4H2 +10% SF6 + 5% izo-C4H10

In Beam Test - July 2005

SMSMGRPC

Beam

FOPI RPC module

Charge Spectra7 kV 7.4 kV

M3 - Plastic scintillator

M4 - Plastic scintillator

Detector response as a function of HV

Detector performance as a function of rate

Start Time Resolution

Start resolutionfor the last runs

Start resolutionfor the first runs

•It shows that being a parasite to a parasite is not the best solution even during the R&D phase.

•Using blindly new electronics, adjusted for different purposes, is not the right thing to do either.

•The observed trends are due to a combined effect of counting rate & electronics setting.

Pestov glass prototype

Differential Strip RPC

Standard Strip RPC Differential Strip RPC

ALICE MRPC-TDR

ALICE MRPC-TDR Addendum

Advantages: - all troubles related to the impedance mismatches should be eliminated - reduced cross-talk- reduced pick-up noise

Diferential readout SMGMSRPC

Conclusions

• SMSMGRPC - recommended for a large portion of the CBM-TOF

• Glaverbel glass prototype should be tested again using properly adjusted electronics if precise resistivity measurements give lower values.

• A 30 cm new prototype using Pestov glass of ~1010 cm is ready to be assembled.

• A prototype with smaller gaps. 220 m or 170 m and very thin intermediate electrodes is under consideration

•Design of similar structures with differential readout (first preliminary electronic tests were reported @ FOPI Trakoscan Meeting-2002) ready and the first prototype will be realized

•When and where the next in-beam tests will take place to be known well in advance

Participants

NIPNE-Bucharest I. Cruceru P. Dima A. Dobrin A. Radu M. Duma D. Moisa M. Petris M. Petrovici V. Simion

GSI - Darmstadt M. Ciobanu M. Marquardt K.D. Hildenbrand J. Weinert M. Kiss A. Schuttauf

Uni - Heidelberg

N. Herrmann E. Cordier