1. RPC R&D status in Bucharest (JRA12-I3HP) Mihai Petrovici - CBM-Meeting, GSI, March 1,2006 Short history SMSMGRPC – Glaverbel Glass Prototype –Construction Details – 60 Co Source Test –In-Beam Test Pestov glass Prototype Differential read-out Prototype Conclusions

2. First tests – 60 Co source - early 2000  = 93 ps  = 90 ps 30 cm length prototype 90 cm length prototype  = 125 ps Plastic scintillator FEE FTA420 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

3. In-Beam Tests – 2001 The dark rate increases from 3.6 Hz/cm 2 @ 5.8 kV to 6Hz/cm 2 @ 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 FEE Cascaded DBAs

4. 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

5. CBM extra requirements: High granularity High counting rate Aging

6. SMSMGRPC – Glaverbel Glass Prototype ●SMSMGRPC with float glass electrodes keeps the performances up to ~1 kHz/cm 2 (  glass ~ 10 12  cm) ●ToF – CBM subdetector – high counting rate environment, up to 20 kHz/cm 2 ●Solutions: –Glass electrodes with lower resistivity –Smaller and many gaps ●Our prototype was built using glaverbel glass with  ~10 10  cm as it was specified by the company !!!

7. 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 mm 2 readout plate: 0.3 x 46 x 980 mm 3 housing: 40 x 80 x 960 mm 3 Al box Construction Details

8. 60 Co Source Test  = 98 ps 85% C 2 F 4 H 2 +10% SF 6 + 5% izo-C 4 H 10

9. In Beam Test - July 2005 SMSMGRPC Beam FOPI RPC module

10. Charge Spectra 7 kV7.4 kV M3 - Plastic scintillator M4 - Plastic scintillator

11. Detector response as a function of HV

12. Detector performance as a function of rate

13. Start Time Resolution Start resolution for the last runs Start resolution for the first runs

14. 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.

15. Pestov glass prototype

16. Differential Strip RPC Standard Strip RPCDifferential Strip RPC

17. ALICE MRPC-TDR

18. ALICE MRPC-TDR Addendum

19. Advantages: - all troubles related to the impedance mismatches should be eliminated - reduced cross-talk - reduced pick-up noise Diferential readout SMGMSRPC

20. 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 ~10 10  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

21. 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