Peter Senger The Compressed Baryonic Matter Experiment at FAIR Critical Point and the Onset of Deconfinement, Florence, July Outline:  The Facility for Antiproton and Ion Research  Compressed Baryonic Matter: the physics case  The CBM detector: challenges and possible solutions  Feasibility studies and Detector R&D

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

Mapping the QCD phase diagram with heavy-ion collisions

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

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

Baryon density in central cell (Au+Au, b=0 fm): HSD: mean field, hadrons + resonances + strings QGSM: Cascade, hadrons + resonances + strings Equilibration in transport calculations C. Fuchs, E. Bratkovskaya, W. Cassing but: only binary collisions even at very high baryon densities !

“Trajectories” from UrQMD H. Stöcker nucl-th/

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

Onset of deconfinement? 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) ?

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  ) 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 & its critical endpoint Observable: event-by-event fluctuations (K/π, p T,...)

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 -

Acceptance for particles identified by TOF 100 % purity:

E-by-E dynamical fluctuations of particle ratios in UrQMD 4pi 2pi CBM Simulations by D. Kresan (GSI), M. Bleicher (Frankfurt): Au+Au 25 AGeV

SIS18 SIS100/ 300 Meson production in central Au+Au collisions W. Cassing, E. Bratkovskaya, A. Sibirtsev, Nucl. Phys. A 691 (2001) 745 (C. Fuchs)

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

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

Dilepton Sources in Heavy-Ion Collisions no ρ,ω,φ → e + e - measurement between 2 and 40 AGeV no J/ψ → e + e - (μ + μ - ) measurement below 160 AGeV

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

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)

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 -

 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 CBM Experiment Silicon Tracking System (STS)

Dipol magnet Silicon Tracking Station Muon detection system Tracking chambers TOF RPC ECAL

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 CBM: 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 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 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

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

C. Blume et al., nucl-ex/ Strangeness/pion ratios versus beam energy

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:

Next steps:  CBM Technical Proposal 2007  CBM Physics Book Workshop at ECT* in Trento May 29 - June 2, 2006 "The physics of high baryon density"

Low-mass di-electron pairs Conceptional studies: MC tracks, ideal particle ID Major background sources: π 0 → γ e + e -, γ → e + e - track segment reconstructed no PID reconstructed PID no magnetic field constant magnetic field 7.5 kG 0 cm 15 cm 200 cm Physical background:  small pair opening angle  often: one hard, one soft electron

E-by-E dynamical fluctuations of particle ratios (NA49) NA49, nucl-ex/

C. Blume et al., nucl-ex/ (CERN NA49) Indication for a phase transition around 30 AGeV ? Strangeness production in central Pb+Pb collisions