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Exploring the QCD Phase Diagram at High Baryon Densities: From SPS to FAIR

Exploring the QCD Phase Diagram at High Baryon Densities: From SPS to FAIR. Claudia Höhne, GSI Darmstadt. QCD phase diagram results from SPS and RHIC CBM physics topics and observables feasibility studies and R&D. QCD phase diagram at high baryon densities.

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Exploring the QCD Phase Diagram at High Baryon Densities: From SPS to FAIR

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  1. Exploring the QCD Phase Diagram at High Baryon Densities: From SPS to FAIR Claudia Höhne, GSI Darmstadt • QCD phase diagram • results from SPS and RHIC • CBM physics topics and observables • feasibility studies and R&D

  2. QCD phase diagram at high baryon densities • intermediate range of the QCD phase diagram with high net-baryon densities of strong interest because of • expected structures as 1st order phase transition and critical point • chiral phase transition [F.Karsch, Z. Fodor, S.D.Katz] • deconfinement = chiral phase transition ? • hadrons and quarks at high m? • signatures (measurable!) for these structures/ phases? • how to characterize the medium?

  3. QCD phase diagram & experiments • What do we know from experiment? → Heavy-ion collisions: • chemical freeze-out curve • top SPS, RHIC (high T, low mB): partonic degrees of freedom, crossover (?) • RHIC: first steps towards a quantitative characterization of the medium (gluon density, viscosity, energy loss...) • lower SPS (intermediate T-mB): • intriguing observations around 30 AGeV! • SIS, AGS: high density baryonic matter [Andronic et al. Nucl. Phys. A 772, 167 (2006).

  4. Experimental scan of QCD phase diagram • Within the next years we'll get a complete scan of the QCD phase diagram with 2nd generation experiments • LHC, RHIC: bulk observables and • rare probes (charm, dileptons) • RHIC energy scan: bulk observables • √s ~ (5)10 GeV – 200 GeV • NA61: focus on fluctuations • (√sNN = 4.5 – 17.3 GeV), A < 120 • NICA: strangeness, bulk observables • (√sNN = 3 – 9 GeV) • CBM: bulk observables and rare • probes (charm, dileptons) • beam energy 10 – 45 GeV/nucleon • (√sNN = 4.5 – 9.3 GeV) • HADES: bulk observables, dileptons • beam energy 2 – 10 GeV/nucleon LHC RHIC CBM, NA61, NICA HADES FAIR beam intensities: up to 109 ions/s [Andronic et al. Nucl. Phys. A 772, 167 (2006).

  5. SPS results • energy dedendence of hadron production • → changes in SPS energy regime • discussions ongoing: • hadron gas → partonic phase • baryon dominated → meson dominated matter • missing: high precision measurements, systematic • investigations, correlations, rare probes • → quantitative characterization of the medium! [NA49, PRC 77, 024903 (2008)] [Andronic et al. Nucl. Phys. A 772, 167 (2006).]

  6. High net baryon densities at low SPS energies [NA49, compilation C. Blume] • low SPS/ AGS energies: high net-baryon densities at mid-rapidity • change to nearly net-baryon free region at RHIC • change of shape most pronounced at SPS energies: peak → dip NA49 preliminary construction of total net-baryon distribution: Sx from stat. model fits Central Pb+Pb/Au+Au Statistical Model F. Becattini et al., Phys. Rev. C73 (2006), 044905. NA49 (158) Phys. Rev. Lett. 82 (1999), 2471 E802 Phys. Rev. C 60 (1999), 064901 BRAHMS Phys. Rev. Lett. 93 (2004), 102301

  7. High net-baryon density matter at CBM • high baryon and energy densities created in central Au+Au • remarkable agreement between different models (not shown) [CBM physics group, C. Fuchs, E. Bratkovskaya priv. com.]

  8. Elliptic flow • all particles flow (even D-mesons!) • scaling if taking the underlying number of quarks into account! • → like (all!) quarks flow and combine to hadrons at a later stage (hadronisation) • data can only be explained assuming a • large, early built up pressure in a nearly • ideal liquid (low viscosity!) [PHENIX, PRL.98:162301,2007] baryons n=3 mesons n=2 KET=mT-m

  9. Elliptic flow • data at top SPS support hypothesis of early development of collectivity • influence of hadronic rescattering phase, resonance decay? • lack of complete thermalization, viscosity effect? • larger pt-range needed Pb+Pb collisions, √sNN = 17.3 GeV [NA49, G. Stefanek, PoS CPOD2006:030,2006]

  10. Elliptic flow central midcentral peripheral • → stiffness of medium (EOS), pressure • collapse of elliptic flow of protons at lower energies signal for first order phase transition?! particle identified flow data for large pt-range! [NA49, PRC68, 034903 (2003)] [Paech, Reiter, Dumitru, Stoecker, Greiner, NPA 681 (2001) 41] ? Elab ~ 30 AGeV

  11. Elliptic flow at FAIR AMPT calculations: C.M. Ko at CPOD 2007 ... including charm! probe for dense matter!

  12. Charm production in hadronic and partonic matter Statistical hadronization model (SHM) (c-cbar in partonic phase) Hadronic model (HSD) [A. Andronic, P. Braun-Munzinger, K. Redlich, J. Stachel, arXiv:0708.1488] O. Linnyk, E.L. Bratkovskaya, W. Cassing, H. Stöcker, Nucl.Phys.A786:183-200,2007 NN → D Λc N NN → DD NN NN → J/ψ NN

  13. Charm production in hadronic and partonic matter no charm (J/y) data below 158 AGeV beam energy detailed information including phase space distributions!

  14. Critical point • critical region might be small • focussing effect? • fluctuations would need time to develop [Schaefer, Wambach, PRD75, 085015 (2007)] [Asakawa, Bass, Mueller, Nonaka, PRL 101, 122302 (2008)]

  15. Event-by-event fluctuations • observation might become enormously difficult • correlation length x of sigma field, may become rather small for a finite lifetime of the fireball • large acceptance needed! 1st try to identify 1st order phase transition line fluctuations, correlations with large acceptance and particle identification [NA49 collaboration, arXiv:0810.5580v2 [nucl-ex]] [Stephanov, Rajagopal, Shuryak, PRD60, 114028 (1999)]

  16. CBM: Physics topics and Observables • The equation-of-state at high B • collective flow of hadrons • particle production at threshold energies (open charm) • Deconfinement phase transition at high B • excitation function and flow of strangeness (K, , , , ) • excitation function and flow of charm (J/ψ, ψ', D0, D, c) • charmonium suppression, sequential for J/ψ and ψ' ? • QCD critical endpoint • excitation function of event-by-event fluctuations (K/π,...) • Onset of chiral symmetry restoration at high B • in-medium modifications of hadrons (,, e+e-(μ+μ-), D) predictions? clear signatures? →prepare to measure "everything" including rare probes → systematic studies! (pp, pA, AA, energy) aim: probe & characterize the medium! - importance of rare probes!!

  17. The CBM experiment • tracking, momentum determination, vertex reconstruction: radiation hard silicon pixel/strip detectors (STS) in a magnetic dipole field • hadron ID: TOF (& RICH) • photons, p0, h: ECAL • PSD for event characterization • high speed DAQ and trigger → rare probes! • electron ID: RICH & TRD •  p suppression  104 • muon ID: absorber + detector layer sandwich •  move out absorbers for hadron runs ECAL TOF TRD RICH absorber + detectors STS + MVD magnet

  18. STS tracking – heart of CBM Challenge: high track density:  600 charged particles in  25o @ 10MHz • Task • track reconstruction: 0.1 GeV/c < p  10-12 GeV/c Dp/p ~ 1% (p=1 GeV/c) • primary and secondary vertex reconstruction (resolution  50 mm) • V0 track pattern recognition radiation hard and fast silicon pixel and strip detectors ct = 312 mm self triggered FEE high speed DAQ and trigger online track reconstruction!

  19. Track reconstruction • max: up to ~109 tracks/s in the silicon • tracker (10 MHz, ~100 tracks/event) • start scenario for D more like 0.1 MHz • → 107 tracks/s • → fast track reconstruction! • optimize code, port C++ routines to dedicated hardware • parallel processing → today: factor 120000 speedup of tracking code achieved! • long term aim: make use of manycore architectures of new generation graphics cards etc. GeForce 9600 64 core GPU

  20. Successful test of CBM prototype detector systems with free-streaming read-out electronics using proton beams atGSI, September 28-30, 2008 2 Double-sided silicon microstrip detectors GSI and AGH Krakow KIP Heidelberg VECC Kolkata Double and triple GEM detectors Radiation tolerance studies for readout electronics Full readout and analysis chain: Go4 online Detector signals Analysis Front-end board with self-triggering n-XYTER chip Data Acquisition System Readout controller offline

  21. Detector commissioning: Operation on the beam line: 90Sr -spectra ... Correlation of fired channels in two silicon microstrip detectors ... in several channels of a silicon microstrip detector ... and in a GEM detector Beam spot seen on a GEM detector (every 2nd channel read out) Participants: GSI, Darmstadt, GermanyJINR, Dubna, RussiaKIP, Heidelberg, GermanyVECC, Kolkata, IndiaAGH, Krakow, Poland www-cbm.gsi.de

  22. CBM hardware R&D Forward Calorimeter RICH mirror Silicon microstrip detector GEM dipole magnet MVD: Cryogenic operation in vacuum n-XYTER FEB RPC R&D

  23. Micro Vertex Detecor (MVD) Development Artistic view of the MVD • mechanical system integration • material for cooling! • → material budget! • vacuum compatibility • Monolithic Acitive Pixel Sensors in commercial CMOS process • 1010 mm2 pixels fabricated, • e > 99%, Dx ~ 1.5 – 2.5 mm die thinned to 50 mmglued to support. IPHC, Strasbourg (M. Winter et al.)

  24. D-meson Simulations • CbmRoot simulation framework, GEANT3 implemented through VMC • full event reconstruction: track reconstruction, particle-ID (RICH, TRD, TOF), 2ndary vertex finder • feasibility studies: central Au+Au collisions at 25 AGeV beam energy (UrQMD) • several channels studied: D0, D±, Ds, Lc • signal multiplicities from HSD, stat model (SM); e.g. <D+>HSD = 8.410-5, SM ½ less • important layout studies: MAPS position (5cm , 10cm), thickness (150 mm – 500mm) D- D+ D+→ p+p+K- (ct = 312 mm, BR 9%) D0 → K-p+ (ct = 123 mm, BR 3.85%) Lc → pK-p+ (ct = 60 mm, BR 5%)

  25. CBM feasibility studies D0 • feasibility studies performed for all major channels including event reconstruction and semirealistic detector setup di-electrons di-muons r w f Lc r w f J/y J/y y' y'

  26. Be prepared for exotica: multi-strange di-baryons p p- L2 p (X0L)b L1 p- Particle identification with CBM Signal: strange dibaryon (0)b   (cτ=3cm) M= 10-6, BR = 5% Background: Au+Au @ 25 AGeV 32  per central event 11  reconstructable KS0 Λ π K p χ2primary> 3()

  27. Detector layout optimization: RICH • first ansatz: gaseous RICH detector (N2 radiator), ~ 100 m3 volume, 200k channels for photodetector (photomultiplier, pixel size appr. 6x6 mm2), Be mirrors (glass coating) • optimization process: ~40 m3 volume, CO2 radiator, 55k channels, glass mirrors RICH + TRD 75% efficiency 104p suppression photodetector: H8500 MAPMT, UV glass window 15 – 22 hits/ring

  28. Detector layout optimization: Muon absorber hit density after 1st absorber central Au+Au collisions at 25 AGeV 10 cm Fe 20 cm Fe 40 20 20 20 25 30 cm Fe 40 cm Fe 30 20 20 20 35 20 20 20 30 35 10 20 30 30 35 total absorber length 125 cm = 7.5 lI

  29. Summary – physics of CBM • CBM@FAIR – high mB, moderate T: • searching for the landmarks of the QCD phase diagram • first order deconfinement phase transition • chiral phase transition • QCD critical endpoint • → systematic measurements, rare probes • characterizing properties • of baryon dense matter • in medium • properties of hadrons? • in A+A collisions from • 10-45 AGeV • (√sNN = 4.5 – 9.3 GeV) • starting in 2016 at SIS 300

  30. CBM + HADES @ SIS 100 in 2014 Rigidity Bρ = 100 Tm: Au beam 10 AGeV Ni beam 14 AGeV p beam 30 GeV HADES:electrons, hadrons CBM "light" (magnet, Silicon tracker, TOF): p, K, π, Λ, Ξ, Ω, ..., flow, fluctuations, up to Au+Au

  31. CBM @ SIS 100 • A+A collisions at 8 AGeV beam energy, p+A at 30 GeV/c • first feasibility studies: charm production for p+C at 30 GeV/c • multiplicities from HSD 1012 events J/y →m+m- S/B ~150 e 23 % 4 J/ψ→μ+μ- in 109 central events

  32. CBM collaboration China: Tsinghua Univ., Beijing CCNU Wuhan USTC Hefei Croatia: University of Split RBI, Zagreb Univ. Mannheim Univ. Münster FZ Rossendorf GSI Darmstadt Univ. Kashmir, Srinagar Banaras Hindu Univ., Varanasi Korea: Korea Univ. Seoul Pusan National Univ. Russia: IHEP Protvino INR Troitzk ITEP Moscow KRI, St. Petersburg Hungaria: KFKI Budapest Eötvös Univ. Budapest Norway: Univ. Bergen Kurchatov Inst. Moscow LHE, JINR Dubna LPP, JINR Dubna India: Aligarh Muslim Univ., Aligarh IOP Bhubaneswar Panjab Univ., Chandigarh Gauhati Univ., Guwahati Univ. Rajasthan, Jaipur Univ. Jammu, Jammu IIT Kharagpur SAHA Kolkata Univ Calcutta, Kolkata VECC Kolkata Poland: Krakow Univ. Warsaw Univ. Silesia Univ. Katowice Nucl. Phys. Inst. Krakow Cyprus: Nikosia Univ. LIT, JINR Dubna MEPHI Moscow Obninsk State Univ. PNPI Gatchina SINP, Moscow State Univ. St. Petersburg Polytec. U. Czech Republic: CAS, Rez Techn. Univ. Prague France: IPHC Strasbourg Portugal: LIP Coimbra Romania: NIPNE Bucharest Bucharest University Ukraine: INR, Kiev Shevchenko Univ. , Kiev Germany: Univ. Heidelberg, Phys. Inst. Univ. HD, Kirchhoff Inst. Univ. Frankfurt 55 institutions, > 400 members Dubna, Oct 2008

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