The CBM Experiment @ FAIR Volker Friese Gesellschaft für Schwerionenforschung Darmstadt HI physics at intermediate beam energies CBM detector concept

The CBM Experiment @ FAIR

Volker Friese

Gesellschaft für Schwerionenforschung

Darmstadt

HI physics at intermediate beam energies CBM detector concept feasibility studies status

Volker Friese QM 2005, Budapest, August 2005 2

HI collisions at intermediate energies

beam energies 10 – 45 AGeV give access to:

highest baryon densities onset of phase transition (?) critical point (?)


Trajectories in the QCD phase diagram

V.Toneev et al., nucl-th/0309008

3 fluid hydro calculation with hadron gas EOS

predicts 30 AGeV to hit critical point

phase boundary reached already at 10 AGeV


Indications for onset of deconfinement at low SPS energies

NA49 (QM 2004)

peak in strange/nonstrange yield ratioplateau of kaon slopes at SPSnot satisfactorily explained in hadronic scenarios

Hama et al., Braz. J. Phys. 34 (2004) 322Gazdzicki, Gorenstein,

Act. Phys. Polon. B 30 (1999) 2705

can be modeled assuming 1st order phase transition


Hadrons in dense environment

CERES, Phys. Rev. Lett. 91, 042301 (2003)

enhancement of low-mass dileptons stronger in 40 AGeV than in 158 AGeV

even larger effect at lower energies?

statistics and resolution must be improved to discriminate different in-medium scenarios


J/ψ suppressionNA50, QM 2005 Gazdzicki & Gorenstein,

Phys. Rev. Lett. 83 (1999) 4009

anomalous suppression observed at top SPS in J/ψ / DYbut J/ψ / h- flat vs centrality (?)onset of suppression at lower energies ?


Charm near threshold

Gorenstein et alJ. Phys. G 28 (2002) 2151

predictions of ccbar production differ strongly between production scenarios (pQCD / QGP / hadron gas)

strongest differences near threshold

experiment should be able to discriminate


Charm in dense matter

Cassing et al, Nucl. Phys. A 691 (2001) 753

Mishra et al, nucl-th/0308082

D meson masses are expected to drop in dense environment

should have strong effect on production yield


Charm in dense matter (ctd.)Mishra et al, nucl-th/0308082

effect of reduced affectiv D mass:strong decay channels open for charmonium statesobservable in J/ψ yield in dileptons ?


The physics of CBM

in-medium propertiesof hadrons

deconfinement at high ρB

critical point

strangeness (K, Λ, Σ, Ξ, Ω)charm (J/ψ, D)

flow

ρ, ω, φ → e+e-

open charm

fluctuations

? !


FAIR @ GSI

SIS 100 Tm

SIS 300 Tm

U: 35 AGeV

p: 90 GeV


Detector considerations

fast detector response

and readout

radiation harddetectors and

electronics

efficient onlineevent selection

high interaction rates(beam intensity 109/s,

high availability)

rare observables(Ω, J/ψ, D)

STStracking,

displaced vertices

ECALlepton IDphotons

TOFhadron ID

RICHelectron ID

TRDelectron ID


Baseline detector concept

beam

magnet

STS ( 5 – 100 cm)

RICH(1,5 m)

TRDs(4,6,8 m)

TOF(10 m)

ECAL(12 m)


The Silicon Tracking System

vacuum

1

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3

4vertexing

tracking

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6

pixel detectors strip detectors

z = 5,10,(20) cm

z = (20),40,60,80,100 cm

"minimal setup": 3 pixel stations4 strip stations

momentum resolution < 1 %


RICH Designrequests:electron ID p < 10 GeV/cpion suppression > 100pion ID p > 4-5 GeV/c

mirror: Be glass, r=450 cmtwo focal planesradiator: γ > 38 (e. g. N2)

z (beam)

y

optical layout

rings in focal plane

ring radius vs momentum


TRD

serves for e/π separationand trackingposition resolution 300 μmcount rates up to 150 kHz/cm2

R&D ongoing for fast gas detectorsReadout: MWPC/GEM/Straw tube

beam test July 2004, GSI

TR-Simulation


Detector performance: acceptance

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bulk of produced hadrons covered by acceptance


Detector performance: J/ψ

15 AGeV 25 AGeV 35 AGeV

single electron pt

Simulation:J/ψ, D – HSDbackground – UrQMDmomentum resolution 1 %pion suppression 104

pt cut 1 GeV/c, S/B ≈ 1count rate 105/week


Detector performance: D mesons

Simulation: STS only (no PID)with MAPS

1011 events

Challenge: Implementation of secondary vertex cut in online event selection (reduction ≈ 1000 needed)


CBM: StatusNov. 2001: FAIR Conceptual Design Report

Jul. 2002: FAIR Recommendation by german Wissenschaftsrat

Feb. 2003: approved by BMBF

Jan. 2004: CBM Letter of Intent

Jan. 2005: CBM Technical Status Report

Next step: Technical Proposal (ca. 2 years)

First beam on target in 2014


The CBM collaboration

Croatia: RBI, Zagreb

Cyprus: Nikosia Univ. Czech Republic:Czech Acad. Science, RezTechn. Univ. Prague France: IReS Strasbourg

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

Romania: NIPNE Bucharest

Russia:CKBM, St. PetersburgIHEP ProtvinoINR TroitzkITEP MoscowKRI, St. PetersburgKurchatov Inst., MoscowLHE, JINR DubnaLPP, JINR DubnaLIT, JINR DubnaPNPI GatchinaSINP, Moscow State Univ.

Spain: Santiago de Compostela Univ. Ukraine: Univ. Kiev

Hungaria:KFKI BudapestEötvös Univ. Budapest

Italy: INFN Frascati

Korea:Korea Univ. SeoulPusan National Univ.

Norway:Univ. Bergen

Poland:Jagiel. Univ. Krakow Silesia Univ. KatowiceWarsaw Univ.Warsaw Tech. Univ. Portugal: LIP Coimbra

Documents

The CBM Experiment @ FAIR Volker Friese Gesellschaft für Schwerionenforschung Darmstadt HI physics at intermediate beam energies CBM detector concept