The CBM Experiment FAIR

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The CBM Experiment _at_ FAIR
Volker Friese Gesellschaft für Schwerionenforschun
g Darmstadt

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

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HI collisions at intermediate energies

• beam energies 10 45 AGeV give access to
• highest baryon densities
• onset of phase transition (?)
• critical point (?)

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Trajectories in the QCD phase diagram
3 fluid hydro calculation with hadron gas
EOS predicts 30 AGeV to hit critical
point phase boundary reached already at 10 AGeV
V.Toneev et al., nucl-th/0309008
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Indications for onset of deconfinement at low SPS
energies
peak in strange/nonstrange yield ratio plateau of
kaon slopes at SPS not satisfactorily explained
in hadronic scenarios
can be modeled assuming 1st order phase transition
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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
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J/? suppression
NA50, QM 2005
Gazdzicki Gorenstein, Phys. Rev. Lett. 83
(1999) 4009
anomalous suppression observed at top SPS in J/?
/ DY but J/? / h- flat vs centrality (?) onset of
suppression at lower energies ?
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Charm near threshold
predictions of ccbar production differ strongly
between production scenarios (pQCD / QGP / hadron
gas) strongest differences near
threshold experiment should be able to
discriminate
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Charm in dense matter
Mishra et al, nucl-th/0308082
D meson masses are expected to drop in dense
environment should have strong effect on
production yield
Cassing et al, Nucl. Phys. A 691 (2001) 753
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Charm in dense matter (ctd.)
Mishra et al, nucl-th/0308082
effect of reduced affectiv D mass strong decay
channels open for charmonium states observable in
J/? yield in dileptons ?
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The physics of CBM
?
!
deconfinement at high ?B
strangeness (K, ?, S, ?, O) charm (J/?, D) flow
in-medium properties of hadrons
?, ?, f ? ee- open charm
critical point
fluctuations
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FAIR _at_ GSI
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Detector considerations
high interaction rates (beam intensity 109/s,
high availability)
rare observables (O, J/?, D)
fast detector response and readout
radiation hard detectors and electronics
efficient online event selection
STS tracking, displaced vertices
ECAL lepton ID photons
TOF hadron ID
RICH electron ID
TRD electron ID
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Baseline detector concept
TOF (10 m)
ECAL (12 m)
RICH (1,5 m)
magnet
beam
TRDs (4,6,8 m)
STS ( 5 100 cm)
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The Silicon Tracking System
"minimal setup" 3 pixel stations 4 strip
stations
momentum resolution lt 1
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RICH Design
requests electron ID p lt 10 GeV/c pion
suppression gt 100 pion ID p gt 4-5 GeV/c
mirror Be glass, r450 cm two focal
planes radiator ? gt 38 (e. g. N2)
optical layout
rings in focal plane
ring radius vs momentum
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TRD
beam test July 2004, GSI
serves for e/p separation and tracking position
resolution 300 µm count rates up to 150 kHz/cm2
TR-Simulation
RD ongoing for fast gas detectors Readout
MWPC/GEM/Straw tube
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Detector performance acceptance
incl. TOF
?
O
?
bulk of produced hadrons covered by acceptance
10
35
AGeV
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Detector performance J/?
single electron pt
Simulation J/?, D HSD background
UrQMD momentum resolution 1 pion suppression 104
pt cut 1 GeV/c, S/B 1 count rate 105/week
15 AGeV
25 AGeV
35 AGeV
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Detector performance D mesons
Simulation STS only (no PID) with MAPS
Challenge Implementation of secondary vertex cut
in online event selection (reduction 1000
needed)
1011 events
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CBM Status
Nov. 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
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The CBM collaboration
Romania NIPNE Bucharest Russia CKBM, St.
Petersburg IHEP Protvino INR Troitzk ITEP
Moscow KRI, St. Petersburg Kurchatov Inst.,
Moscow LHE, JINR Dubna LPP, JINR Dubna LIT, JINR
Dubna PNPI Gatchina SINP, Moscow State Univ.
Spain Santiago de Compostela Univ.
  Ukraine Univ. Kiev
Croatia RBI, Zagreb Cyprus Nikosia Univ.
  Czech Republic Czech Acad. Science,
Rez Techn. Univ. Prague   France IReS
Strasbourg Germany Univ. Heidelberg, Phys.
Inst. Univ. HD, Kirchhoff Inst. Univ.
Frankfurt Univ. Mannheim Univ. Marburg Univ.
Münster FZ Rossendorf GSI Darmstadt    
Hungaria KFKI Budapest Eötvös Univ.
Budapest Italy INFN Frascati
Korea Korea Univ. Seoul Pusan National
Univ. Norway Univ. Bergen Poland Jagiel.
Univ. Krakow Silesia Univ. Katowice Warsaw
Univ. Warsaw Tech. Univ.   Portugal LIP
Coimbra