the cbm experiment @ fair volker friese gesellschaft für schwerionenforschung darmstadt hi physics...
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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 (?)
Volker Friese QM 2005, Budapest, August 2005 3
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
Volker Friese QM 2005, Budapest, August 2005 4
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
Volker Friese QM 2005, Budapest, August 2005 5
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
Volker Friese QM 2005, Budapest, August 2005 6
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 ?
Volker Friese QM 2005, Budapest, August 2005 7
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
Volker Friese QM 2005, Budapest, August 2005 8
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
Volker Friese QM 2005, Budapest, August 2005 9
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 ?
Volker Friese QM 2005, Budapest, August 2005 10
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
? !
Volker Friese QM 2005, Budapest, August 2005 11
FAIR @ GSI
SIS 100 Tm
SIS 300 Tm
U: 35 AGeV
p: 90 GeV
Volker Friese QM 2005, Budapest, August 2005 12
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
Volker Friese QM 2005, Budapest, August 2005 13
Baseline detector concept
beam
magnet
STS ( 5 – 100 cm)
RICH(1,5 m)
TRDs(4,6,8 m)
TOF(10 m)
ECAL(12 m)
Volker Friese QM 2005, Budapest, August 2005 14
The Silicon Tracking System
vacuum
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4vertexing
tracking
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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 %
Volker Friese QM 2005, Budapest, August 2005 15
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
Volker Friese QM 2005, Budapest, August 2005 16
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
Volker Friese QM 2005, Budapest, August 2005 17
Detector performance: acceptance
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incl. TOF
10 35AGeV
Λ Ξ Ω
bulk of produced hadrons covered by acceptance
Volker Friese QM 2005, Budapest, August 2005 18
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
Volker Friese QM 2005, Budapest, August 2005 19
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)
Volker Friese QM 2005, Budapest, August 2005 20
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
Volker Friese QM 2005, Budapest, August 2005 21
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