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Prospects for strangeness and charm measurements in the CBM experiment

Prospects for strangeness and charm measurements in the CBM experiment. Volker Friese GSI Darmstadt. Strangeness in Quark Matter 2009, Búzios, 1 October 2009. Experimental landscape. RHIC energy scan: Collider, moderate rates, bulk probes.

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Prospects for strangeness and charm measurements in the CBM experiment

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  1. Prospects for strangeness and charm measurements in the CBM experiment Volker Friese GSI Darmstadt Strangeness in Quark Matter 2009, Búzios, 1 October 2009

  2. Experimental landscape RHIC energy scan: Collider, moderate rates, bulk probes SPS (NA61): Fixed target, moderate rates, emphasis on light ions, bulk probes NICA (MPD): collider (see talk by A. Sorin) FAIR (CBM): Fixed target, high rates, bulk + rare probes Volker Friese

  3. CBM: experimental setup TOF ECAL TRD RICH PSD Electron + Hadron setup Muon setup absorber + detectors STS+MVD • Tracking in STS • Vertexing in MVD • Electron ID in RICH + TRD • Hadron ID in TOF • γ in ECAL • Centrality in PSD • μ ID in absorber system Volker Friese

  4. Hadron identification by TOF TOF: 150 m2 RPC Pad / strip readout 80 ps resolution at 10 m from target Charged kaon identification track-by-track up to p = 3.5 GeV Volker Friese p

  5. Particle ratio fluctuations Sensitivity to K/π fluctuations studied with UrQMD input (central Au+Au, 25A GeV) No large bias compared to MC truth found after full reconstruction and identification CBM acceptance appears well suited for fluctuation studies CBM MC truth Volker Friese

  6. Hyperon measurements central Au+Au @ 25A GeV Identified by decay topology in main tracker + inv. Mass Clean signals: almost background free for Λ and Ξ Λ Ξ- Ω- Volker Friese

  7. Multi-strange di-baryons Thermal production yields for hyperon clusters Started to study {Ξ0, Λ} → ΛΛ Assuming: m=mΛ + mΞ cτ = 3 cm (1-5 cm) BR = 2 % (1-10 %) {Ξ0, Λ} J. Schaffner-Bielich, R. Mattiello and H. Sorge, 1999 J. Steinheimer, priv. comm. Volker Friese

  8. ΛΛ simulation and analysis Transport event display Λ reconstruction Require off-vertex Λ Cut on ΛΛ vertex Volker Friese

  9. Results and sensitivity for {Ξ0, Λ} Sensitivity limit: 7  10-6 Thermal multiplicity (7  10-3) CBM will see {Ξ0, Λ} with thermal yields Evene three OOM below the signal will be visible above BG Volker Friese

  10. Micro-vertex detection For efficient background suppression imn open charm measurements: detection of displaced vertex indispensable Requires: high-precision, low-mass silicon detector Current choice: 2 station of MAPS, operated in vacuum Promising results on vertex resolution Volker Friese

  11. Open charm detection D+ -> K- π+ π+ : cτ = 312 μm Cuts on: Daughter impact parameter Vertex geometrical fit Vertex topological fit Clean D+ signal observed Volker Friese

  12. Open charm : statistics Typical runtime 25 d @ 106 events / s ≈ 16 k D+ decays measured Good rapidity and pt coverage Volker Friese

  13. Open charm: other channels D0 -> K- π- π+ π+ D0 -> K- π+ + c.c. Ds+ -> K- K+ π+ Λc+ -> p K- π+ Volker Friese

  14. Open charm: summary Volker Friese

  15. Open charm: challenges • High event rates (105 – 106) indispensable • Requires: • Online trigger reduction by factor > 100 • Online track reconstruction and SV detection • Fast micro-vertex detector • MAPS: Limited by readout, 10 μs frame rate possible • Simulations: Event pile-up of 10 – 20 tolerable • Radiation-hard detector: up to 1014 neq/cm2/year • R&D on MAPS radiation tolerance ongoing • Regular replacement of MAPS stations feasible Volker Friese

  16. Open charm trigger Based on: impact parameter of daughters geometrical and topological vertex cuts Rejection factors > 100 in reach To be implemented in FLES Volker Friese

  17. Performance for charmonium μ+μ- e+e- J/ψ peak well observable; similar performance in electron and muon channel ψ‘ at edge of feasibility Measurements requires highest event rates (107 / s) Volker Friese

  18. New DAQ concept FLES ABB ABB BNet Extreme event and data rates (up to 1 TB/s from FEE) require new DAQ and FLES strategies No convential trigger mode, but self-triggered, free-streaming FEE with time tags FEE and DAQ components under development and testing at GSI; first successful test of free-streaming R/O chain in 2008 digitization aggregation buffering processing correlation FEB DCB Det ROC Volker Friese

  19. Fast event reconstruction CPU time for track reconstruction and fit FLES has to reduce the raw data rate (1 TB/s) to the recordable rate (1 GB/s) Necessity of (partial) event reconstruction online at MHz rates Novel algorithms and implementations to exploit modern / future computer architectures Paradigmata: vectorisation and parallelisation Current event reconstruction time in STS: 50 ms Volker Friese

  20. CBM on track: ongoing R&D RPChigh-rate glass substr. GEM for MUCH in beam test AUG09. self-triggering read-out chips 128 ch, 32 MHz radiation hard silicon microstrip detectors STS in beam test AUG09 MAPS TRD high-rate Data Acquisition System throughput 500 MB/s/node Readout ASICs for RPC Time-of-flight system: 25 ps time resolution Partial cherenkov ring From RICH beam test AUG09 Volker Friese

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