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CBM The future of relativistiv heavy-ion physics at GSI

CBM The future of relativistiv heavy-ion physics at GSI. V. Friese Gesellschaft f ür Schwerionenforschung Darmstadt, Germany v.friese@gsi.de. Tracing the Onset of Deconfinement in Nucleus-Nucleus Collisions Trento Workshop April 2004. SIS 100/300. Double-ring synchrotron

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CBM The future of relativistiv heavy-ion physics at GSI

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  1. CBMThe future of relativistiv heavy-ion physics at GSI V. Friese Gesellschaft für Schwerionenforschung Darmstadt, Germany v.friese@gsi.de Tracing the Onset of Deconfinement in Nucleus-Nucleus Collisions Trento Workshop April 2004

  2. SIS 100/300 Double-ring synchrotron 1100 m circumference 100 / 300 Tm Cooler/Storage rings (CR, NESR, HESR) SIS Unilac • Experimental areas for: • nuclear structure • plasma physics • antiproton physics • nuclear collisions • atomic physics HESR Existing facility serves as injector SuperFRS NESR The planned facility in Darmstadt A "next generation" accelerator facility: 2 Deconfinement Workshop, Trento, April 2004 V. Friese

  3. Design Goals Excellent beam quality Highest beam intensities 3 Deconfinement Workshop, Trento, April 2004 V. Friese

  4. Design Goals (2) Parallel operation for different physics programmes 4 Deconfinement Workshop, Trento, April 2004 V. Friese

  5. Design goals (3) Higher beam energies Heavy-ion beams 2 – 35 AGeV Slow extraction, continuous beam 1010 ions/s up to Uranium Light ions (Z/A=1) up to 45 AGeV 5 Deconfinement Workshop, Trento, April 2004 V. Friese

  6. Project Status November 2001 Conceptual Design Report Cost estimate 675 M € July 2002 German Wissenschaftsrat recommends realisation February 2003 German Federal Gouvernment decides to build the facility. Will pay 75 % January / April 2004 Letters of Intent submitted 6 Deconfinement Workshop, Trento, April 2004 V. Friese

  7. Timescale 7 Deconfinement Workshop, Trento, April 2004 V. Friese

  8. The Times they are a' changing 8 Deconfinement Workshop, Trento, April 2004 V. Friese

  9. lattice QCD : Fodor / Katz, Nucl. Phys. A 715 (2003) 319 RHIC SPS SIS300 dense bayonic medium dilute hadron gas hadronic phase nuclei The Future GSI and the QCD Phase Diagram ... operating at highest baryon densities ... maybe reaching deconfinement ... maybe close to the critical point 9 Deconfinement Workshop, Trento, April 2004 V. Friese

  10. Why another experiment? We have data from AGS ( - 12 AGeV) and SPS (20 AGeV - ) but : • studying the dense hadronic phase requires penetrating probes: dileptons • studying the onset of deconfinement requires systematic (energy, system size) measurements of hadronic observables The qualitatively new feature of the future accelerator: Highest beam intensities (109 ions/s) give access to rare probes (ρ,dileptons, Ω, D, J/Ψ) 10 Deconfinement Workshop, Trento, April 2004 V. Friese

  11. Physcis Topics and Observables 1. In-medium modifications of hadrons onset of chiral symmetry restorationat high B measure: , ,   e+e- open charm (D mesons) 2. Indications for deconfinement at high B  enhanced strangeness production ? measure: K, , , ,   charm production ? measure: J/, D softening of EOS measure flow excitation function 3. Critical point event-by-event fluctuations 4. Color superconductivity precursor effects at T>Tc ? 11 Deconfinement Workshop, Trento, April 2004 V. Friese

  12. Predictions of open charm yield differ by orders of magnitude for different production scenarios, especially at low energies Gorenstein et al J. Phys. G 28 (2002) 2151 A physics example : Charm production Soft A dependence : <D> ~ <h-> ~ Np pQCD : <D> ~ A2 ~ Np4/3 Hadron gas in chemical equilibrium Canonical suppression analoguous to strangeness Equilibrated QGP + statistical coalescence 12 Deconfinement Workshop, Trento, April 2004 V. Friese

  13. Open charm in dense matter Various QCD inspired models predict a change of D mass in hadronic medium Mishra et al, nucl-th/0308082 Substantial change (several 100 MeV) already at =0 In analogy to kaon mass modification, but drop for both D+ and D- Effect for charmonium is substantially smaller 13 Deconfinement Workshop, Trento, April 2004 V. Friese

  14. Cassing et al, Nucl. Phys. A 691 (2001) 753 HSD : D yield enhanced by a factor of 7 at 25 AGeV! Reduced D meson mass : consequences If the D mass is reduced in the medium: DD threshold drops below charmonium states Mishra et al, nucl-th/0308082 • Decay channels into DD open for ’, c, J/ • broadening of charmonium states • suppression of J/ • enhancement of D mesons 14 Deconfinement Workshop, Trento, April 2004 V. Friese

  15. Caveats and Advantages Only one slot for relativistiv nuclear collisions at future GSI  Build an "universal experiment" for both hadronic and leptonic probes, covering as many obervables as possible High beam intensity, quality and duty cycle High availability due to parallel operation of accelerator  Possibility of systematic measurements: beam energy (10 – 35/45 AGeV) system size even of very rare probes! 15 Deconfinement Workshop, Trento, April 2004 V. Friese

  16. W. Cassing et al, Nucl. Phys. A 691(2001) 753 Challenges : rare probes in heavy-ion environment Au+Au @ 25 AGeV charge muliplicity ≈ 1000 D multiplicity 10-4 – 10-3 need : high event rates highly selective trigger 16 Deconfinement Workshop, Trento, April 2004 V. Friese

  17. central Au+Au @ 25 AGeV, UrQMD + GEANT Conditions and requirements High track multiplicity (700-1000) Beam intensity 109 ions/sec. High interaction rate (10 MHz) Need fast and radiation hard detectors Detector tasks: Tracking in high-density environment STS + TRD Reconstruction of secondary vertices (resolution  50 m) STS Hadron identification :  / K / p separation (t  80 ps) TOF Lepton identification :  / e separation (pion suppression 10-4) TRD + RICH Myon / photon measurements ECAL 17 Deconfinement Workshop, Trento, April 2004 V. Friese

  18. The CBM detector Setup in GEANT4 18 Deconfinement Workshop, Trento, April 2004 V. Friese

  19. magnet Radiation hard Silicon pixel/strip detectors Tracking System Requirements: Radiation hardness Low material budget Fast detector response Good positon resolution Monolothic Active Pixel Sensors Pitch 20 m Low material budget : Potentially d = 20 m Excellent single hit resolution :  3 m S/N = 20 - 40 19 Deconfinement Workshop, Trento, April 2004 V. Friese

  20. Tracking reconstructed tracks Reconstruction efficiency > 95 % Momentum resolution ≈ 0.6 % 20 Deconfinement Workshop, Trento, April 2004 V. Friese

  21. Hadron identification σTOF = 80 ps Bulk of kaons (protons) can well be identified with σTOF = 80 – 100 ps 21 Deconfinement Workshop, Trento, April 2004 V. Friese

  22. R&D FOPI Upgrade Detector resolution 90 cm-14 strips-4 gaps t < 80 ps Tail < 2% RPC developments for TOF Challenge for TOF : Huge counting rate (25 kHz/cm2) Large area (130 m2 @ 10 m) 22 Deconfinement Workshop, Trento, April 2004 V. Friese

  23. TRD • Requirements • hit rate up to 500 kHz per cell • fast readout (10 MHz) • Duties • e/ separation • tracking • Anticipated setup • 9 layers in three stations (z = 4m / 6m / 8m) • area per layer 25 / 50 / 100 m2 • channels per layer 35 k / 55 k / 100 k For most of the system state-of-the art (ALICE) is appropriate. For the inner part, R&D on fast gas detectors in progress Readout options : drift chamber / GEM / straw tubes 23 Deconfinement Workshop, Trento, April 2004 V. Friese

  24. TRD Wire chamber readout studied at GSI requires small drift times  thin layers  more layers Pion efficiency of < 1% reachable with 9 layers extrapolated from single ALICE-type chamber 24 Deconfinement Workshop, Trento, April 2004 V. Friese

  25. RICH Optical layout for RICH1 • Duties • e/ separation • K/ separation ? horizontal plane vertical plane Mirror: Beryllium / glass Two focal planes (3.6 m2) separated vertically 25 Deconfinement Workshop, Trento, April 2004 V. Friese

  26. RICH Radiator gas: C4H10 + N2 (thr = 16 – 41) Photodetectors: photomultipliers or gas detectors RICH1: thr = 41  p,thr = 5.7 GeV  (almost) hadron blind 26 Deconfinement Workshop, Trento, April 2004 V. Friese

  27. RICH Kaon ID by TOF deteriotes quickly above 4 GeV Kaon ID by RICH for p > 4 GeV would be desirable Option for RICH2 ? thr = 30  p,thr = 4.2 GeV, pK,thr=15 GeV Problem: Ring finding in high hit density environment 27 Deconfinement Workshop, Trento, April 2004 V. Friese

  28. Self triggered digitization: Dead time free Detector Front end ADC Each hit transported as Address/Timestap/Value Compensates builder/selector latency Buffer memory Use time correlation of hits to define events. Select and archive. Event builder and selector DAQ / Trigger Architecture clock Practically unlimited size Max. latency uncritical Avr. latency relevant Challenge : reconstruct 1.5 x 109 track/sec. data volume in 1st level trigger  50 Gbytes/sec. 28 Deconfinement Workshop, Trento, April 2004 V. Friese

  29. Crucial detector parameters: Material in tracking stations Single hit resolution Feasibility study : open charm D0 K-+ (central Au+Au @ 25 AGeV) c = 124 m, BR = 3.8 % BG suppression 2 x 105 Assuming <D0> = 10-3 : S/B  1 SNR = 3 at 2 x 106 events detection rate 13,000 / h Key variable to suppress background: secondary vertex position Similar study for D+  K-+ + (c = 315 m, BR = 9 %) First estimate S/B  3 29 Deconfinement Workshop, Trento, April 2004 V. Friese

  30. Feasibility study: J/  e+e- Extremely rare signal! Background from various sources: Dalitz, conversion, open charm... Very efficient cut on single electron pT S/B > 1 should be feasible 30 Deconfinement Workshop, Trento, April 2004 V. Friese

  31. Feasibility study : Light vector mesons Background sources: Dalitz, conversion no easy pT cut; sophisticated cutting strategy necessary depends crucially on elimination of conversion pairs by trackingand charged pion discrimination by RICH and TRD (104) S/B = 0.3 (ρ+) S/B = 1.2 () idealised: no momentum resolution 31 Deconfinement Workshop, Trento, April 2004 V. Friese

  32. The CBM Collaboration Russia: CKBM, St. Petersburg IHEP Protvino INR Troitzk ITEP Moscow KRI, St. Petersburg Kurchatov Inst., Moscow LHE, JINR Dubna LPP, JINR Dubna LIT, JINR Dubna Obninsk State University PNPI St. Petersburg SINP, Moscow State Univ. Spain: Santiago de Compostela Univ. Ukraine: Shevshenko Univ. , Kiev University of Kharkov USA: LBNL Berkeley Croatia: RBI, Zagreb Cyprus: Nikosia Univ. Czech Republic: Czech Acad. Science, Rez Techn. Univ. Prague France: IReS Strasbourg Germany: Univ. Heidelberg, Phys. Inst. Univ. HD, Kirchhoff Inst. Univ. Frankfurt Univ. Mannheim Univ. Marburg Univ. Münster FZ Rossendorf FZ Jülich GSI Darmstadt Hungaria: KFKI Budapest Eötvös Univ. Budapest Italy: INFN Catania INFN Frascati Korea: Korea Univ. Seoul Pusan Univ. Norway Univ. of Bergen Poland: Krakow Univ. Warsaw Univ. Silesia Univ. Katowice Portugal: LIP Coimbra Romania: NIPNE Bucharest 32 Deconfinement Workshop, Trento, April 2004 V. Friese

  33. Summary • CBM will operate at the future facility from 2012 on • It will measure nucleus-nucleus collisions from 10 – 35 / 45 AGeV at interaction rates of 10 MHz • The key observables will be rare probes like multiple strange hyperons, open and hidden charm and dileptonic decays of light vector mesons • These will (hopefully) give insight into the properties of baryonic matter at extreme densities and into the transition to a deconfined state • (Still) open for new ideas! • The collaboration has been formed; detector R&D is started or starting • CDR : November 2001, LoI : January 2004 • Next milestone: Progress Report 2004 / 2005 33 Deconfinement Workshop, Trento, April 2004 V. Friese

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