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The Compressed Baryonic Matter Experiment at FAIR

The Compressed Baryonic Matter Experiment at FAIR

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The Compressed Baryonic Matter Experiment at FAIR

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  1. The Compressed Baryonic Matter Experiment at FAIR Peter Senger, GSI Bergen, April 3, 2005 Outline:  Physics case  Detector requirements  Feasibility studies Detector R&D  Outlook

  2. The future Facility for Antiproton an Ion Research (FAIR) Primary beams: 1012 /s 238U28+ 1-2 AGeV 4·1013/s Protons 90 GeV 1010/s U 35 AGeV (Ni 45 AGeV) Secondary beams: rare isotopes 1-2 AGeV antiprotons up to 30 GeV SIS 100 Tm SIS 300 Tm cooled antiproton beam: Hadron Spectroscopy Ion and Laser Induced Plasmas: High Energy Density in Matter Structure of Nuclei far from Stability low-energy antiproton beam: antihydrogen Compressed Baryonic Matter

  3. States of strongly interacting matter baryons hadrons partons Compression + heating = quark-gluon matter (pion production) “Strangeness" of dense matter ? In-medium properties of hadrons ? Compressibility of nuclear matter? Deconfinement at high baryon densities ? Neutron stars Early universe

  4. Mapping the QCD phase diagram with heavy-ion collisions ε=0.5 GeV/fm3 SIS100/300 Critical endpoint: Z. Fodor, S. Katz, hep-lat/0402006 S. Ejiri et al., hep-lat/0312006

  5. “Trajectories” (3 fluid hydro) Hadron gas EOS V.Toneev, Y. Ivanov et al. nucl-th/0309008 Top SPS energies: baryonic matter not equilibrated

  6. Diagnostic probes U+U 23 AGeV

  7. CBM physics topics and observables  In-medium modifications of hadrons onset of chiral symmetry restorationat high B measure: , ,   e+e- open charm (D mesons)  Strangeness in matter production and propagation of strange particles measure: K, , , ,  Theory working group on Dense Baryonic Matter Kick-off Meeting June 13, 2005, GSI Goal: CBM Physics Book (end of 2006)  Indications for deconfinement at high B production and propagation of charm measure:J/, D  Critical point event-by-event fluctuations

  8. J/ψ measurement requires high beam intensities and lepton identification central collisions 25 AGeV Au+Au 158 AGeV Pb+Pb J/ multiplicity 1.5·10-5 1·10-3 beam intensity 1·109/s 2·107/s interactions 1·107/s (1%) 2·106/s (10%) central collisions 1·106/s 2·105/s J/ rate 15/s 200/s 6% J/e+e- (+-) 0.9/s 12/s spill fraction 0.8 0.25 acceptance 0.25  0.1 J/ measured 0.17/s  0.3/s  1·105/week 1.8·105/week

  9. D-meson measurement requires vertex resolution D meson production in pN collisions Some hadronic decay modes D(c = 317 m): D+  K0+(2.90.26%) D+  K-++ (9  0.6%) D0(c = 124.4 m): D0  K-+ (3.9  0.09%) D0  K-+ + - (7.6  0.4%) Measure displaced vertex with resolution of  50 μm !

  10. ρ,ω, φ e+e- requires electron identification Dominant background: π0-Dalitz decay and gamma conversion. Important: identification of soft electrons/positrons ! D.Adamova et al., PRL 91 (2003) 042301 CERES 2000: 159 AGeV Pb+Au beam intensity: 106 ions / spill 1 spill = 4 s beam and 15 s pause targets: 13 x 25 μm Au ( ~ 1 % interaction) trigger: 8% most central Event rate = 470 / spill (~ 25 Hz = 15 Mio events/week)

  11. Alternative option: ρ,ω, φ, J/ψμ+μ- NA60 preliminary: In+In 158 AGeV

  12. Hadron identification requires TOF C. Blume et al., nucl-ex/0409008

  13. Photon (π0, η) measurements: electromagnetic calorimeter Photon yield measured by WA98 Phys. Rev. Lett. 93 (022301), 2004 Pb+Pb 158 AGeV 10% central collisions

  14. The CBM Experiment  Radiation hard Silicon (pixel/strip) Tracking Systemin a magnetic dipole field  Electron detectors: RICH & TRD & ECAL: pion suppression better 104  Hadron identification: TOF-RPC  Measurement of photons, π0, η, and muons: electromagn. calorimeter (ECAL)  High speed data acquisition and trigger system

  15. Experimental challenges Central Au+Au collision at 25 AGeV: URQMD + GEANT4 160 p, 400 -, 400 +, 44 K+, 13 K-,....  107 Au+Au reactions/sec (beam intensities up to 109 ions/sec, 1 % interaction target)  determination of (displaced) vertices with high resolution ( 50 m) identification of electrons and hadrons If simultaneous measurement of all observables is impossible: optimized running conditions and dedicated subdetectors

  16. Tracking with the Silicon Tracking System High track density:  600 charged particles in  25o track finding efficiency momentum resolution Assumptions: ideal detector response, hit resolution 10 μm, no pile-up events Requirements: track hits more than 3 stations

  17. Silicon Pixel Vertex Detector Silicon Tracking System: 2 (3) Pixel Stations/ 5 (4) Strip Stations Vertex tracking: two pixel layers (5 cm and 10 cm downstream target) • Design goals: • low materal budget: d < 200 μm • single hit resolution < 20 μm • radiation hard (dose 1015 neq/cm2) • read-out time 25 ns • Roadmap: • R&D on Monolithic Active Pixel Sensors (MAPS) • thickness below 100 μm • pitch 20 μm, single hit resolution :  3 μm • radiation tolerant (1013 neq/cm2) • ultimate read-out time few μs Alternative: next generation of thin, radiation hard, fast hybrid detectors MIMOSA IV IReS / LEPSI Strasbourg

  18. Silicon Strip Tracker 4 Strip tracking stations Tracking Stations Nr. 4 and 6 Double sided Si-Strip detectors: thickness 100 μm pitch 25 μm Stereo angle 15o

  19. Track reconstruction with realistic STS detector response 1. Monolythic Active Pixel Sensors (MAPS): read-out time of about 5μs achievable. at reaction rate of 10 MHz: pile-up of about 50 min-bias events Work in progress:  track reconstruction with pile-up events simulation based on Hybrid Pixel detectors  benchmark: D-meson detection 2. Silicon Strip detectors: double sided, stereo angle. fake hits (and fake tracks), Work in progress:  optimization of strip length and orientation of the detector planes  additional planes ?

  20. D0 K-,+signal Background Reconstructed events Z-vertex(cm) D0  K-+ reconstruction Simulations: UrQMD (incl. hyperons) + D meson

  21. D-meson: online event selection Track reconstruction (Kalman filter) without magnetic field, dp/p = 1% ( Similar results with magnetic field) Cuts include: impact parameter 80 μm < b < 500 μm z-vertex 250 μm < b < 5000 μm using track information from MAPS Silicon Tracker only (no particle ID) event reduction by factor 1000: 10 MHz  10 kHz Vertex trigger with MAPS: ≈ 1 MHz reaction rate  ≈300 D mesons per hour

  22. D0  K-+:requirements for Pixel detectors K- and π+ impact-parameter distribution UrQMD (combinatorial background) Signal: D  K-π+ Thresholds: event rejection by factor of 1000 MAPS: 100 μm thickness Hybrid: 700 μm thickness D0 efficiency larger than 1%: hit resolution of better than 20 μm required

  23. Hyperon detection with STS without p, K, π identification • UrQMD central events 25 AGeV • Magnetic field • Silicon detector hits with 10 μm resolution • Ideal track finding (at least 4 MC points) • Momentum and vertex reconstruction with Kalman filter

  24. Invariant mass distributions after topological cuts -- efficiency 15.8% 6.7% 7.7%

  25. Particle identification by TOF Simulations: UrQMD central Au + Au at 25 AGeV GEANT4 with B-field, geometry and material time resolution 80 ps, 10 m distance Squared mass measured with TOF Kaon efficiency π K p

  26. Acceptance for particles identified by TOF 99 % purity: Dynamical fluctuations in particle ratios ?

  27. Event mixing was used to estimate the background UrQMD 4 PID

  28. Fluctuations from NA49 nucl-ex/0403035 NA49, nucl-ex/0403035 • dynamical fluctuations reported by NA49 • increase towards low energies • K/ : not reproduced by UrQMD • p/ : correlation due to resonance decays

  29. Sensitivity on dynamical fluctuations TOF Acceptance Generic model based on UrQMD particle yields: central Au+Au collisions at 25 AGeV:694 , 54 K, 161 p Signals with amplitudes above 2% are well reproduced TOF distance 10 m time resolution 80 ps

  30. Feasibility studies: charmonium measurements Assumptions: no track reconstruction, momentum resolution 1% Pion suppression 104 Background: central Au + Au UrQMD + GEANT4 Cut pT > 1 GeV/c J/ψ 15 AGeV Au+Au Single electron (positron) spectra J/ψ 25 AGeV Au+Au J/ψ 35 AGeV Au+Au

  31. Online selection of J/ψ e+e- using STS and TRD Track – and momentum fitting based on MC hits in STS and TRD: position resolution: σ = 10 μm (STS), σ = 500 μm (TRD) momentum resolution mass resolution

  32. Low mass electron-positron pairs Generic study assuming ideal tracking Background: URQMD Au+Au 25 AGeV + GEANT4 Magnetic fields: 0T, 0.5 T (constant), 1 T (constant) Dominating background:   e+e- 0  e+e- Cuts: 1. reconstruct and remove pairs belowMe+e- 2. single electron: - transverse momentum pt - impact parameter d 3. electron pair: - opening angle α

  33. 56·106 events 35·106 events S/B in the peak: r+wj 0 T 12.5 25 0.5T 3.3 6 1.0T 1.5 4 70·106 events Results assumption: soft electrons identified

  34. Design of a fast RICH • Design goals: • electron ID for γ> 42 • e/π discrimination > 100 • hadron blind up to about 6 GeV/c • low mass mirrors (Be-glass) • fast UV detector URQMD + GEANT4: Au+Au 25 AGeV radiator (40% He + 60% CH4),  50 rings per event, 30-40 photons per ring

  35. Experimental conditions Hit rates for 107 minimum bias Au+Au collisions at 25 AGeV: Rates of > 5 kHz/cm2 detector R&D

  36. Design of a fast TRD • Design goals: • e/π discrimination of > 100 (p > 1 GeV/c) • High rate capability up to 100 kHz/cm2 • Position resolution of about 200 μm • Large area ( 450 - 650 m2, 9 – 12 layers) Simulation of pion suppression: MWPC-based TRD 90% .

  37. Rate performance of TRD prototypes (ALICE type): beam test measurements (p and π) MWPC Dubna MWPC GSI, Bucharest MWPC GSI MWPC (Dubna) GEM (Dubna)

  38. Design of a straw-tube based TRD (ATLAS type) MC simulations: 20 GeV primary particles, 4 mm straws, 2.6 cm radiator with 15 µm foils and 200 µm gap. Design TRD 1 for CBM

  39. Development of a large-area high-rate timing RPC shielded RPC prototype • Design goals: • Time resolution ≤ 80 ps • Rate capability up to 20 kHz/cm2 • Efficiency > 95 % • Large area  100 m2 • Long term stability Multigap RPC (ALICE ) Layout options single cell RPC

  40. RPC prototype tests: time resolution vs. rate Detector with plastic electrodes (resistivity 109 Ohm cm.) New: encouraging results with ceramic electrodes ! Window glass: improved rate capability with increased temperature RPC prototype with phosphate glass

  41. Design of an electromagnetic calorimeter • Design goals: • energy resolution of 5/E(GeV) • high rate capability up to 15 kHz • e/π discrimination of 50-200 • total area 100 m2 Hit density for Au+Au 25 AGeV • Lead-scintillator calorimeter: • 0.5 – 1 mm thick tiles • 25 X0 total length • PM read out • Granularity: • inner region 3x3 cm2 • intermediate region 6x6 cm2 • outer region 12x12cm2

  42. Design of an electromagnetic calorimeter ECAL (Shashlik): E(ECAL)/p(tracker) electrons pions preshower detector electron electron/pion supression using ECAL and preshower detector pion

  43. L1 Select L2 Select Self-triggered FEE – Data Push DAQ Detector Self-triggered front-end Autonomous hit detection fclock FEE No dedicated trigger connectivity All detectors can contribute to L1 Cave Shack DAQ Large buffer depth available System is throughput-limited and not latency-limited High bandwidth Modular design: Few multi-purpose rather many special-purpose modules Special hardware Archive archive rate few GByte/s

  44. CBM R&D working packages FEE, Trigger, DAQ Design & construction of detectors Feasibility studies Simulations Framework GSI Silicon Pixel IReS Strasbourg Frankfurt Univ., GSI Darmstadt, TRD (MWPC) JINR-LHE, Dubna GSI Darmstadt, Univ. Münster NIPNE Bucharest ,ω, e+e- Univ. Krakow JINR-LHE Dubna GSI Darmstadt KIP Univ. Heidelberg Univ. Mannheim Uni. Kaiserslautern GSI Darmstadt JINR-LIT, Dubna Univ. Bergen KFKI Budapest Silesia Univ. Katowice Warsaw Univ. PNPI St. Petersburg NIPNE Bucharest MEPHI Moscow Wuhan Univ. Tracking KIP Univ. Heidelberg Univ. Mannheim JINR-LHE Dubna JINR-LIT Dubna Silicon Strip Moscow State Univ CKBM St. Petersburg KRI St. Petersburg Univ. Obninsk J/ψ e+e- INR Moscow GSI RBI Zagreb TRD (straw) JINR-LPP, Dubna FZ Rossendorf FZ Jülich Tech. Univ. Warsaw Ring finder JINR-LIT, Dubna J/ψμ+μ- PNPi St. Petersburg SPU St. Petersburg RPC-TOF LIP Coimbra, Univ. Santiago Univ. Heidelberg, GSI Darmstadt, NIPNE Bucharest INR Moscow FZ Rossendorf IHEP Protvino ITEP Moscow RBI Zagreb Univ. Marburg Korea Univ. Seoul ECAL ITEP Moscow IHEP Protvino π, K, p ID Heidelberg Univ, Warsaw Univ. Kiev Univ. NIPNE Bucharest INR Moscow D  Kπ(π) GSI Darmstadt, Czech Acad. Sci., Rez Techn. Univ. Prague IReS Strasbourg RICH IHEP Protvino GSI Darmstadt Pusan Univ. PNPI St. Petersburg Magnet JINR-LHE Dubna GSI Λ, Ξ,Ω PNPi St. Petersburg SPU St. Petersburg JINR-LHE Dubna δ-electrons GSI Darmstadt beam det. Univ. Mannheim GSI Darmstadt

  45. CBM Collaboration : 41 institutions, > 300 Members Croatia: RBI, Zagreb China: Wuhan Univ. Cyprus: Nikosia Univ. Czech Republic: CAS, Rez Techn. Univ. Prague France: IReS Strasbourg Hungaria: KFKI Budapest Eötvös Univ. Budapest Korea: Korea Univ. Seoul Pusan National Univ. Norway: Univ. Bergen Germany: Univ. Heidelberg, Phys. Inst. Univ. HD, Kirchhoff Inst. Univ. Frankfurt Univ. Kaiserslautern Univ. Mannheim Univ. Marburg Univ. Münster FZ Rossendorf GSI Darmstadt Poland: Krakow Univ. Warsaw Univ. Silesia Univ. Katowice Portugal: LIP Coimbra Romania: NIPNE Bucharest 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 MEPHI Moscow Obninsk State Univ. PNPI Gatchina SINP, Moscow State Univ. St. Petersburg Polytec. U. Spain: Santiago de Compostela Univ. Ukraine: Shevshenko Univ. , Kiev

  46. The FAIR member states (March 2005) Italy India Romania ? Germany Russia Sweden UK France Poland Finland Spain Greece Obs. EU FAIR Council (Representatives of Institutions) Observ. USA Project Management Obs. China FAIR Project Obs. Hungary