Compressed baryonic matter -Experiments at GSI and at FAIR

Outline:

Probing dense baryonic matter (1-3 ρ0) The nuclear equation-of-state In medium properties of strange mesons

Towards highest baryon densities (3-10 ρ0) 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

• 1011 stored and cooled antiprotons

0.8 - 14.5 GeV

primary beams

• 1012/s; 1.5-2 GeV/u; 238U28+

• factor 100-1000 increased intensity• 4x1013/s 90 GeV protons• 1010/s 238U 35 GeV/u ( Ni 45 GeV/u)

secondary beams

• rare isotopes 1.5 - 2 GeV/u; factor 10 000 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 Understandingfor the FAIR project (as of November 24, 2005)

Romania signed in 2006 Observers: EU, USA, Hungary, Austria

Country Signatory Date

   

Finland Prof. Dr. D. Riska 22.09.2004

France Dr. E. Giacobino 08.12.2004

Germany Dr. H. Schunck 13.09.2004

Greece Prof. Dr. C. Fotakis 11.11.2004

Italy Dr. L. Criscuoli 06.12.2004

Poland Prof. Dr. R. Kulessa 18.01.2005

Russian Federation Dr. S. Mazurenko 11.11.2004

Spain Dr. S. Ordónez Delgado 06.10.2004

Sweden Dr. P. Omling 21.09.2004

United Kingdom Prof. Dr. J. Wood 13.09.2004

China Meng Shuguan / Ma Yanhe 24.11.2005

India Dr. Y.P. Kumar 17.11. 2005

Cost of the FAIR project: ~ 1 Billion € (25% from foreign partners)German Federal Government has approved construction budget over 10 yearsStart of civil construction end of 2007

The phase diagram of strongly interacting matter

RHIC, LHC: high temperature, low baryon densityFAIR: moderate temperature, high baryon density

Critical endpoint:Z. Fodor, S. Katz, hep-lat/0402006S. Ejiri et al., hep-lat/0312006μB < 400 MeV: crossover

ε=0.5 GeV/fm3

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

RHICLHC

Mapping the QCD phase diagram with heavy-ion collisions

lattice QCD

crossover transition

?

recent data from RHIC:Tfreezeout → 165 MeVrecent L QCD calculations:TC → 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/0503088

early phase not in thermodynamic equilibrium !

J. Randrup and J. Cleymans, hep-ph/0607065

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 (D0, 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, pT, ...)

Towards higher baryonic densities

Ch. Fuchs, Tübingen

SIS18 SIS

100/300

Meson production in central Au+Au collisionsW. Cassing, E. Bratkovskaya, A. Sibirtsev, Nucl. Phys. A 691 (2001) 745

In-medium modification of D-mesons

E. Bratkovskaya, W. Cassing

C. Blume et al., nucl-ex/0409008

Strangeness/pion ratios versus beam energy

Decrease of baryon-chemicalpotential: transition frombaryon-dominatedto meson-dominatedmatter

?

Comparison of experimental data to results of transport codes E.L. Bratkovskaya, W. Cassing, M. van Leeuwen, S. Soff, H. Stöcker, nucl-th/0307098

“Flow generated by extra pressure generated by partonic interactions in the early phase of a central Au+Au/Pb+Pb collision”

Intriguing observations by NA49 @ CERN-SPS

coexistence phase

hadronsQGP

critical point

next steps:confirmation of NA49 → Low energy run at RHIC ?comprehensive experimental study → CBM @ 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

pn

++

K

p

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. 2003 ~ 4 × 1012 ions delivered in total

In+In 158 AGeV

Dilepton experiments require: high momentum resolution ( 1 - 2 %) and high statistics

Low mass vector mesons (CERES/CERN)

D.Adamova et al., PRL 91 (2003) 042301 CERES 2000: 159 AGeV Pb+Aubeam intensity: 106 ions / spill 1 spill = 4 s beam and 15 s pausetargets: 13 x 25 μm Au ( ~ 1 % interaction)trigger: 8% most centralEvent 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: Do, D, Ds, c,

global features: collective flow, fluctuations, ..., exotica

Experimental program of CBM@FAIR

Systematic investigations:A+A collisions from 8 to 45 (35) AGeV, Z/A=0.5 (0.4) p+A collisions from 8 to 90 GeVp+p collisions from 8 to 90 GeVBeam energies up to 8 AGeV: HADES

Large integrated luminosity:High beam intensity and duty cycle,Available for several month per year

Detector requirementsLarge geometrical acceptance (azimuthal symmetry !)good hadron and electron identificationexcellent vertex resolutionhigh rate capability of detectors, FEE and DAQ

Experimental challenges

up to 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

Central Au+Au collision at 25 AGeV:URQMD + GEANT4

160 p 400 -

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 104

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 HSD25 AGeV Au+Au from UrQMD

81000 D+ mesons registered in 1012 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

ω φρ

combinatorial background

Electron-positron pairs from Au+Au collisions at 25 AGeV

Simulations without track reconstruction & electron identificationExperimental challenge: branching ratios ~ 10-5-10-4 for ρ,ω,φ → e+e-

major sources of physical background: Dalitz decays π0→ e+e-γ gamma conversion γ → e+e-

Feasibility studies: charmonium measurementsAssumptions:no track reconstruction (momentum resolution 1%)ideal electron identification, pion suppression 104

Background: central Au + Au UrQMD + GEANT4Cut pT > 1 GeV/c

J/ψ15 AGeV Au+Au

25 AGeVAu+Au

35 AGeVAu+Au

J/ψ

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

ρ φω

Problems: low efficiency for small invariant masses (cut-off at 200 MeV/c2 ) 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/cm2

• Position resolution of about 200 μm• Large area ( 450 - 650 m2, 9 – 12 layers)

Resistive Plate Chamber (ToF-RPC): • Time resolution ≤ 80 ps• High rate capability up to 25 kHz/cm2

• Efficiency > 95 %• Area 100 m2

Electromagnetic Calorimeter:• energy resolution of 5/E(GeV) • high rate capability up to 15 kHz• e/π discrimination of 50-200• Area 100 m2

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 1015 neq/cm2)• fast read out

Si-Strip detectors:• pitch 50 μm• thickness 150 μm• double sided, stereo angle 15o

• Area 2 m2

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

HADES2 – 8 AGeV

CBM8 – 45 AGeV

CBM Collaboration : > 40 institutions, > 350 MembersCroatia:

RBI, Zagreb

China:Wuhan Univ.Hefei Univ.

Cyprus: Nikosia Univ.  

Czech Republic:CAS, RezTechn. Univ. Prague

France: IReS Strasbourg

Hungaria:KFKI BudapestEötvös Univ. Budapest

India:VECC KolkataSAHA Kolkata*IOP Bhubaneswar*Univ. Chandighar*Univ. Varanasi*

   

Romania: NIPNE Bucharest

Russia:IHEP ProtvinoINR TroitzkITEP MoscowKRI, St. PetersburgKurchatov Inst., MoscowLHE, JINR DubnaLPP, JINR DubnaLIT, JINR DubnaMEPHI MoscowObninsk State Univ.PNPI GatchinaSINP, Moscow State Univ. St. Petersburg Polytec. U.

Ukraine: Shevshenko Univ. , Kiev

* to be approved by CB

Korea:Korea Univ. SeoulPusan National Univ.

Norway:Univ. Bergen

Germany: Univ. Heidelberg, Phys. Inst.Univ. HD, Kirchhoff Inst. Univ. FrankfurtUniv. KaiserslauternUniv. Mannheim Univ. MünsterFZ RossendorfGSI Darmstadt

Poland:Krakow Univ.Warsaw Univ.Silesia Univ. KatowiceNucl. Phys. Inst. Krakow* 

Portugal: LIP Coimbra

Technical Status Report:http://www.gsi.de/fair/experiments/CBM

Next steps: CBM Physics Book CBM Technical Proposal

Workshop on the Physics of Compressed Baryonic Matter

Dec. 15 – 16, 2005 at GSITransparencies can be found on

http://www-aix.gsi.de/conferences/cbm2005-Dec/

Workshop on the Physics of high baryon density

May 29 - June 2, 2006at 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