Compressed baryonic matter - Experiments at GSI and at FAIR Outline: Probing dense baryonic matter (1-3 ρ 0 )  The nuclear equation-of-state  In medium properties of strange mesons Towards highest baryon densities (3-10 ρ 0 )  Exploring the phases of QCD matter Peter Senger (GSI) Dense Matter In Heavy Ion Collisions and Astrophysics, August 2006, Dubna

Outline:  The Facility for Antiproton and Ion Research  Compressed Baryonic Matter: the physics case  The CBM detector: challenges and possible solutions

storage and cooler rings beams of rare isotopes e – A Collider stored and cooled antiprotons GeV primary beams /s; GeV/u; 238 U 28+ factor increased intensity 4x10 13 /s 90 GeV protons /s 238 U 35 GeV/u ( Ni 45 GeV/u) secondary beams rare isotopes GeV/u; factor increased intensity antiprotons 3(0) - 30 GeV The international Facility for Antiproton and Ion Research accelerator technical challenges Rapidly cycling superconducting magnets high energy electron cooling beam losses

accelerator physics high intensive heavy ion beams dynamical vacuum rapidly cycling superconducting magnets high energy electron cooling Research programs at FAIR Rare isotope beams; nuclear structure and nuclear astrophysics nuclear structure far off stability nucleosynthesis in stars and supernovae Beams of antiprotons: hadron physics quark-confinement potential search for gluonic matter and hybrids hypernuclei high-energy nucleus-nucleus collisions: compressed baryonic matter baryonic matter at highest densities (neutron stars) phase transitions and critical endpoint in-medium properties of hadrons short-pulse heavy ion beams : plasma physics matter at high pressure, densities, and temperature fundamentals of nuclear fusion atomic physics and applied research highly charged atoms low energy antiprotons radiobiology

Status Signatures Memorandum of Understanding for the FAIR project (as of November 24, 2005) Romania signed in 2006 Observers: EU, USA, Hungary, Austria CountrySignatoryDate FinlandProf. Dr. D. Riska FranceDr. E. Giacobino GermanyDr. H. Schunck GreeceProf. Dr. C. Fotakis ItalyDr. L. Criscuoli PolandProf. Dr. R. Kulessa Russian FederationDr. S. Mazurenko SpainDr. S. Ordónez Delgado SwedenDr. P. Omling United KingdomProf. Dr. J. Wood ChinaMeng Shuguan / Ma Yanhe IndiaDr. Y.P. Kumar Cost of the FAIR project: ~ 1 Billion € (25% from foreign partners) German Federal Government has approved construction budget over 10 years Start of civil construction end of 2007

The phase diagram of strongly interacting matter RHIC, LHC: high temperature, low baryon density FAIR: moderate temperature, high baryon density

Phases of QCD picture taken from T. Hatsuda asymptotic freedom pre-formed pairs (strong residual force)

Critical endpoint: Z. Fodor, S. Katz, hep-lat/ S. Ejiri et al., hep-lat/ μ B <  400 MeV: crossover ε =0.5 GeV/fm 3 first order phase transition baryon density:  B  4 ( mT/2  ) 3/2 x [exp((  B -m)/T) - exp((-  B -m)/T)] baryons - antibaryons SIS300 SIS18 SPS RHIC LHC Mapping the QCD phase diagram with heavy-ion collisions lattice QCD crossover transition ? recent data from RHIC: T freezeout → 165 MeV recent L QCD calculations: T C → 190 MeV

Baryon density in central cell (Au+Au, b=0 fm): HSD: mean field, hadrons + resonances + strings QGSM: Cascade, hadrons + resonances + strings C. Fuchs, E. Bratkovskaya, W. Cassing Transport calculations: baryon densities

Baryon density in central cell (Au+Au, b=0 fm): HSD: mean field, hadrons + resonances + strings QGSM: Cascade, hadrons + resonances + strings Transport calculations: energy densities C. Fuchs, E. Bratkovskaya, W. Cassing

“Trajectories” from UrQMD L. Bravina, M. Bleicher et al., PRC 1998

“Trajectories” from 3 fluid hydrodynamics Hadron gas EOS: Y. Ivanov, V. Russkikh, V.Toneev nucl-th/ early phase not in thermodynamic equilibrium !

J. Randrup and J. Cleymans, hep-ph/

Diagnostic probes U+U 23 AGeV

Compressed Baryonic Matter: physics topics and observables Search for chiral symmetry restoration at high  B  in-medium modifications of hadrons Observables: , ,   e + e -, open charm,..... Search for a deconfined phase at high  B  enhanced strangeness production ? Observables: K, , , ,   anomalous charmonium suppression ? Observables: charmonium (J/ψ, ψ'), open charm (D 0, D  ),  c Probing the equation-of-state at high  B Observables: collective flow of hadrons, particle production at threshold energies (open charm) Search for the 1. order phase transition & the critical endpoint Observable: event-by-event fluctuations (K/π, p T,...)

Towards higher baryonic densities Ch. Fuchs, Tübingen

SIS18 SIS 100/300 Meson production in central Au+Au collisions W. Cassing, E. Bratkovskaya, A. Sibirtsev, Nucl. Phys. A 691 (2001) 745

In-medium modification of D-mesons E. Bratkovskaya, W. Cassing

Signatures of the quark-pluon plasma ? Anomalous suppression of charmonium (J/  ) ??? 1 fm CC

C. Blume et al., nucl-ex/ Strangeness/pion ratios versus beam energy Decrease of baryon-chemical potential: transition from baryon-dominated to meson-dominated matter ?

Comparison of experimental data to results of transport codes E.L. Bratkovskaya, W. Cassing, M. van Leeuwen, S. Soff, H. Stöcker, nucl-th/ “Flow generated by extra pressure generated by partonic interactions in the early phase of a central Au+Au/Pb+Pb collision”

Intriguing observations by CERN-SPS coexistence phase hadrons QGPQGP critical point next steps:  confirmation of NA49 → Low energy run at RHIC ?  comprehensive experimental study → FAIR ? Pb+Pb (non-equilibrium fluctuations) ?

E-by-E dynamical fluctuations of particle ratios in UrQMD 4pi 2pi CBM Interpretation of e-by-e fluctuations of particle abundances requires detailed information about contribution of resonance decays Simulations by D. Kresan (GSI), M. Bleicher (Frankfurt): Au+Au 25 AGeV

p n  ++  K   p e+e+ e-e-  Looking into the fireball … … using penetrating probes: short-lived vector mesons decaying into electron-positron pairs

Dilepton Sources in Heavy-Ion Collisions

Dimuon pairs measured by NA60 (CERN) 5-week-long run in Oct.–Nov ~ 4 × ions delivered in total In+In 158 AGeV Dilepton experiments require: high momentum resolution ( %) and high statistics

Radiation-hard silicon pixel detectors (LHC development) Idea: identify prompt dimuon pairs and those from decaying D-Dbar pairs by precise vertex-determination Upgrade of NA50 at CERN-SPS: indirect measurement of D-mesons 10 planes 88 pixel readout chips channels pixel size : 50  425  m 2

Low mass vector mesons (CERES/CERN) D.Adamova et al., PRL 91 (2003) CERES 2000: 159 AGeV Pb+Au beam intensity: 10 6 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) Calculations by R. Rapp: thick dashed line: unmodified rho thick dashed-dotted line: in-medium dropping rho mass thick solid line: in-medium spread rho width no ρ,ω,φ → e + e - measurement between 2 and 40 AGeV no J/ψ → e + e - (μ + μ - ) measurement below 160 AGeV

Observables: Penetrating probes: , , , J /  → e+e- (μ+μ-) Strangeness: K, , , , , Open charm: D o, D , D s,  c, global features: collective flow, fluctuations,..., exotica Experimental program of Systematic investigations: A+A collisions from 8 to 45 (35) AGeV, Z/A=0.5 (0.4) p+A collisions from 8 to 90 GeV p+p collisions from 8 to 90 GeV Beam energies up to 8 AGeV: HADES Large integrated luminosity: High beam intensity and duty cycle, Available for several month per year Detector requirements Large geometrical acceptance (azimuthal symmetry !) good hadron and electron identification excellent vertex resolution high rate capability of detectors, FEE and DAQ

Experimental challenges  up to 10 7 Au+Au reactions/sec (beam intensities up to 10 9 ions/sec, 1 % interaction target)  determination of (displaced) vertices with high resolution (  50  m)  identification of electrons and hadrons Central Au+Au collision at 25 AGeV: URQMD + GEANT4 160 p 400   + 44 K + 13 K -

 Radiation hard Silicon (pixel/strip) Tracking System in a magnetic dipole field  Electron detectors: RICH & TRD & ECAL: pion suppression better 10 4  Hadron identification: TOF-RPC  Measurement of photons, π, η, and muons: electromagn. calorimeter (ECAL)  High speed data acquisition and trigger system The Compressed Baryonic Matter Experiment Silicon Tracking System (STS)

Acceptance for particles identified by TOF 100 % purity: Very important for the measurement of event-by-event fluctuations: a large and azimuthally symmetric acceptance

Hyperon detection with STS without p, K, π identification   -  - efficiency 15.8% 6.7% 7.7% (uds)(dss) (sss) central Au+Au collisions at 25 AGeV:

Track reconstruction: realistic magnetic field, 7 pixel detectors (no strips yet), no particle ID required D + mesons from Au+Au collisions at 25 AGeV D + production cross section from HSD 25 AGeV Au+Au from UrQMD D + mesons registered in min. bias Au+Au collisions at 25 AGeV → 1 day run with fast and rad hard vertex detector and tracking trigger → 100 days run with todays MAPS vertex detector without trigger

Signal/Background (  1.4 σ): s/b = 0.5 at mass of ω meson s/b = 0.3 at mass of φ meson ωφ ρ combinatorial background Electron-positron pairs from Au+Au collisions at 25 AGeV Simulations without track reconstruction & electron identification Experimental challenge: branching ratios ~ for ρ,ω,φ → e + e - major sources of physical background:  Dalitz decays π 0 → e + e - γ  gamma conversion γ → e + e -

Feasibility studies: charmonium measurements Assumptions: no track reconstruction (momentum resolution 1%) ideal electron identification, pion suppression 10 4 Background: central Au + Au UrQMD + GEANT4 Cut p T > 1 GeV/c J/ψ 15 AGeV Au+Au 25 AGeV Au+Au 35 AGeV Au+Au J/ψ Single electron (positron) spectra ongoing work:  track reconstruction (STS-TRD)  electron identification (RICH+TRD)

Study of μ ID system with absorber for CBM C/Fe absorbers + detector layers Simulations Au+Au 25 AGeV:  track reconstruction from hits in STS and muon chambers (100 μm position resolution)  muon ID: tracks from STS to muon chamber behind absorber  vector meson multiplicities from HSD transport code J/ψ→μ+μ- s/b ~ 100 ρφω Problems:  low efficiency for small invariant masses (cut-off at 200 MeV/c 2 )  low efficiency for soft muons from ρ, ω, φ → μ+μ-  Challenging muon detector (high particle densities)

Experimental requirements and ongoing R&D Transition Radiation Detector: e/π discrimination of > 100 (p > 1 GeV/c) High rate capability up to 100 kHz/cm 2 Position resolution of about 200 μm Large area (  m 2, 9 – 12 layers) Resistive Plate Chamber (ToF-RPC): Time resolution ≤ 80 ps High rate capability up to 25 kHz/cm 2 Efficiency > 95 % Area 100 m 2 Electromagnetic Calorimeter: energy resolution of 5  /  E(GeV) high rate capability up to 15 kHz e/π discrimination of Area 100 m 2 FEE and DAQ: self triggered digitization, dead time free Silicon Pixel (Vertex) Detector: low materal budget: d < 200 μm single hit resolution < 20 μm radiation hardness (dose n eq /cm 2 ) fast read out Si-Strip detectors: pitch 50 μm thickness 150 μm double sided, stereo angle 15 o Area 2 m 2 Ring Imaging Cherenkov Detector: e/π discrimination > 100 hadron blind up to about 6 GeV/c low mass mirrors fast UV detector Muon detection system: fast gas chambers (GEM) high granularity

HADES 2 – 8 AGeV CBM 8 – 45 AGeV

CBM Collaboration : > 40 institutions, > 350 Members Croatia: RBI, Zagreb China: Wuhan Univ. Hefei Univ. Cyprus: Nikosia Univ. Czech Republic: CAS, Rez Techn. Univ. Prague France: IReS Strasbourg Hungaria: KFKI Budapest Eötvös Univ. Budapest India: VECC Kolkata SAHA Kolkata* IOP Bhubaneswar* Univ. Chandighar* Univ. Varanasi* Romania: NIPNE Bucharest Russia: 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. Ukraine: Shevshenko Univ., Kiev * to be approved by CB 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. Münster FZ Rossendorf GSI Darmstadt Poland: Krakow Univ. Warsaw Univ. Silesia Univ. Katowice Nucl. Phys. Inst. Krakow* Portugal: LIP Coimbra

Technical Status Report: Next steps:  CBM Physics Book  CBM Technical Proposal Workshop on the Physics of Compressed Baryonic Matter Dec. 15 – 16, 2005 at GSI Transparencies can be found on Workshop on the Physics of high baryon density May 29 - June 2, 2006 at ECT* in Trento, Italy

Baryon density in central cell (Au+Au, b=0 fm): HSD: mean field, hadrons + resonances + strings QGSM: Cascade, hadrons + resonances + strings Transport calculations: equilibrated system ? C. Fuchs, E. Bratkovskaya, W. Cassing