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Final Parameters for the FOPI RPC upgrade

Final Parameters for the FOPI RPC upgrade. Everard Cordier (Heidelberg University, Germany). Outline: RPC-6 gaps performance (test Nov-Dec 03) RPC-8 gaps performance (test Aug 04) Application for CBM Next steps Conclusions. CBM MEETING Oct 2004.

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Final Parameters for the FOPI RPC upgrade

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  1. Final Parameters for the FOPI RPC upgrade Everard Cordier (Heidelberg University, Germany) • Outline: • RPC-6 gaps performance (test Nov-Dec 03) • RPC-8 gaps performance (test Aug 04) • Application for CBM • Next steps • Conclusions CBM MEETING Oct 2004

  2. Full system test Nov-Dec 03 (CDC+RPC) System: U+Au @ 900 AMeV (~ 6.105 events in total) Gap 300μm Glass 1mm RPC 90*4.6 cm²/6 gaps/14strips Intrinsic performance (start counter unfolded) • Single hit :time resolution  75ps, efficiency>96% • Multihit : time resolution  95ps, efficiency>90% Particle identification : momentum and velocity Time difference spectrum for fast pions (single and double hits)

  3. Strong cuts on CDC tracks quality Background 0.5% Background 2.5% Mass cuted (GeV/c2) Background studies Status in April 04 : background (single and double hit) ~ 5%

  4. New electronics (Aug 04)(see talk K. Koch) Time resolution  25 ps Next step (last) : 1 round with new connectors (Samtec) Next time resolution  20 ps ?

  5. Darkrate  1Hz/cm2 New long counter 8 gaps, 14 strips glass plates : 1.1/0.5mm gap size : 250μm Darkrate

  6. 90 cm 2mm strip 1mm gap What is a cluster ? Each event can fire several strips • A cluster is defined by the number of strips fired for one event • The cluster size (or width) is the mean obtained for several events In multihit situation the width should be as small as possible

  7. Direct P/π beam Cluster and charge studies Linear increase of mean and width of clusters with the voltage In the inefficient region of the RPC mean and RMS of the charge distribution are nearly constant. When the counter gets fully efficient it’s a linear rise of both Smaller cluster size and better charge distribution for 8 gaps than for 6 gaps

  8. Timing and efficiency results Needed for CBM

  9. We can optimize cluster distribution and charge Operating window of the 8 gap RPC At a voltage between 11.75-12.5 Cluster width <2 strips Charge mean far away from threshold () Fully efficient >98 % Time resolution <65 ps

  10. Could be covered by FOPI counters (33 % of the total area) Can already be covered by FOPI counters (25 % of the total area) Application for CBM Resolution at 100 Hz / cm2 : 60 ps at 1 kHz / cm2 : 85 ps Estimation (linear extrapolation) : 80 ps for a rate of 820 Hz / cm2 Au+Au @ 25 AGeV Interaction rate 107 10% central collisions (Plot from L. Slusarczyk) Total area of the TOF wall at 10 meters : 150 m2 Total area with rate  1 kHz/ cm2 : 50 m2 Total area with rate  800 Hz/ cm2 : 38 m2

  11. Next stepSupermodule test Nov 04 : • Build the supermodule 0 : 5 long RPCs (8 gap 250 μm, 16 strips, 1.1/0.5 mm glass) + new FEE (Samtec connectors) + new Taquila + new mechanics • Beam test : full system performance with high statistics

  12. People GSI-KPI : M.Ciobanu K.Hildenbrand M.Marquardt A.Schüttauf A.Weinert GSI-DVEE E.Badura R.Hardel K.Koch HD-University E.Cordier N.Herrmann A.Mangiarotti IPNE, Bucharest M.Petrovici V.Simion Conclusion Next step FOPI • TestSupermodule 0(5MRPCs 8 gap) in experiment with high statistics with full FOPI system. Adopt this solution for the TOF ugrade. Next step CBM • Determine time resolution needed (simulations) • Increase performance (new electronics, gas or glass studies) • Cover a large part of the TOF wall with this RPCs ? Thank you !!!

  13. From Peter Senger (Oct 6. 04)

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