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Strangeness and charm of Compressed Baryonic
Matter The CBM Experiment at FAIR
Peter Senger

• Outline
• ? Exploring high baryon densities
• ? Experimental observables
• ? A second generation experiment

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The future Facility for Antiproton an Ion
Research (FAIR)
SIS 100 Tm SIS 300 Tm U 35 AGeV p 90 GeV
Cooled antiproton beam Hadron Spectroscopy
Ion and Laser Induced Plasmas High Energy
Density in Matter
Structure of Nuclei far from Stability
Compressed Baryonic Matter
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States of strongly interacting matter
baryons hadrons partons

Compression heating quark-gluon
plasma (pion production)
Strangeness" of dense matter ? In-medium
properties of hadrons ? Compressibility of
nuclear matter? Deconfinement at high baryon
densities ?
Neutron stars
Early universe
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Mapping the QCD phase diagram with heavy-ion
collisions
SIS300
net baryon density ?B ? 4 ( mT/2?h2c2)3/2 x
exp((?B-m)/T) - exp((-?B-m)/T) baryons
- antibaryons
Lattice QCD calculations Fedor Katz, Ejiri et
al.
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Trajectories (3 fluid hydro)
Ivanov Toneev
Hadron gas EOS
Calculations reproduce freeze-out conditions 30
AGeV trajectory close to the critical endpoint
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Strangeness production in central AuAu and
PbPb collisions
Experimental situation Strangeness enhancement ?
SIS 100 300
SIS 100 300
Statistical hadron gas model P. Braun-Munzinger
et al. Nucl. Phys. A 697 (2002) 902
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Diagnostic probes UU 23 AGeV
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CBM physics topics and observables
? In-medium modifications of hadrons ?
onset of chiral symmetry restoration at high ?B
measure ?, ?, ? ? ee-
open charm (D mesons)
? Strangeness in matter (strange matter?)
? enhanced strangeness production ?
measure K, ?, ?, ?, ?
? Indications for deconfinement at high ?B
? anomalous charmonium suppression ?
measure J/?, D
? Critical point ? event-by-event
fluctuations
? Color superconductivity ?
precursor effects ?
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Electron-positron pairs from PbAu at 40 AGeV
CERES Collaboration S.
Damjanovic and K. Filimonov, nucl-ex/0109017
185 pairs!
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J/? experiments a count rate estimate
central collisions 25 AGeV AuAu 158 AGeV
PbPb J/?? multiplicity
1.510-5 110-3 beam
intensity 1109/s
2107/s interactions
1107/s (1) 2106/s (10) central
collisions 1106/s
2105/s J/? rate
15/s 200/s 6
J/???ee- (??-) 0.9/s
12/s spill fraction
0.8 0.25
acceptance 0.25
? 0.1 J/? measured
0.17/s ? 0.3/s
? 1105/week
? 1.8105/week
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Open charm
D meson production in pN collisions
Some hadronic decay modes D? (c? 317 ?m) D ?
K0? (2.9?0.26) D ? K-?? (9 ? 0.6) D0 (c?
124.4 ?m) D0 ? K-? (3.9 ? 0.09) D0 ? K-?
? ?- (7.6 ? 0.4)
Measure displaced vertex with resolution of ?
30 µm !
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Meson production in central AuAu collisions
W. Cassing, E. Bratkovskaya, A. Sibirtsev, Nucl.
Phys. A 691 (2001) 745
SIS100/ 300
SIS18
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Experimental challenges
Central AuAu collision at 25 AGeV URQMD
GEANT4 160 p 400 ?- 400 ? 44 K
13 K-

• ? 107 AuAu reactions/sec
• (beam intensities up to 109 ions/sec, 1
  interaction target)
• ? determination of (displaced) vertices with high
  resolution (? 30 ?m)
• ? identification of electrons and hadrons

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Feasibility studies
Event generators URQMD, PLUTO Transport
GEANT3,4 via VMC
? Radiation hard Silicon pixel/strip detectors in
a magnetic dipole field ? Electron detectors
RICH TRD ECAL pion suppression up to 105 ?
Hadron identification RPC, RICH ? Measurement
of photons, p0, ?, and muons electromagn.
calorimeter (ECAL)
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Hadron identification
sTOF 80 ps
Bulk of kaons (protons) can well be identified
with sTOF 80 100 ps
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Low mass electron-positron pairs
Assumptions ideal tracking and electron
identification Background URQMD AuAu 25 AGeV
GEANT4

• Cuts
• 1. single electron
• pt gt 0.1 GeV/c
• d lt 50 mm
• 2. electron pair
• vz lt 0.1 cm
• vt lt 0.01 cm
• D lt 0.01 cm
• T gt 10

S/B 0.3 (??) S/B 1.2 (?)
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Pion misidentification
a)0
b)0.01
c)0.1
d)1
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Feasibility studies charmonium measurements
Assumptions ideal tracking
ideal electron identification,
Pion suppression 104 Background URQMD
AuAu 25 AGeV GEANT4
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Feasibility study open charm
Background suppression by cut on detached vertex
? 1000
D0 ? K-? (central AuAu _at_ 25 AGeV) Assuming
ltD0gt 10-3 S/B ? 1
Similar studies under way for D ? K- ? ?
, D?D0 ?
Crucial detector parameters Material budget of
first 2 Silicon stations Single hit resolution
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Design of a Silicon Pixel detector
Silicon Tracking System 7 planar layers of
pixels/strips. Vertex tracking by two first pixel
layers at 5 cm and 10 cm downstream target

• Design goals
• low materal budget d lt 200 µm
• single hit resolution lt 20 µm
• radiation hard (dose 1015 neq/cm2)
• fast read out

• Roadmap
• RD on Monolithic Active Pixel Sensors (MAPS)
• pitch 20 µm
• thickness below 100 µm
• single hit resolution ? 3 µm
• Problem radiation hardness and readout speed
• Fallback solution Hybrid detectors

MIMOSA IV IReS / LEPSI Strasbourg
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Experimental conditions
Hit rates for 107 minimum bias AuAu collisions
at 25 AGeV
Rates of gt 10 kHz/cm2 in large part of detectors
! ? main thrust of our detector design studies
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CBM RD working packages
FEE, Trigger, DAQ
Feasibility studies Simulations
Design construction of detectors
?,?, ? ?ee- Univ. Krakow JINR-LHE Dubna
Framework GSI
Silicon Pixel IReS Strasbourg Frankfurt
Univ., GSI Darmstadt, RBI Zagreb, Univ. Krakow
Fast TRD JINR-LHE, Dubna GSI Darmstadt, Univ.
Münster NIPNE Bucharest
KIP Univ. Heidelberg Univ. Mannheim GSI
Darmstadt JINR-LIT, Dubna Univ. Bergen KFKI
Budapest Silesia Univ. Katowice Univ. Warsaw
Tracking KIP Univ. Heidelberg Univ.
Mannheim JINR-LHE Dubna JINR-LIT Dubna
J/? ? ee- INR Moscow GSI
Straw tubes JINR-LPP, Dubna FZ Rossendorf FZ
Jülich Tech. Univ. Warsaw
Silicon Strip Moscow State Univ CKBM St.
Petersburg KRI St. Petersburg Univ. Obninsk
J/? ? µµ- PNPi St. Petersburg SPU St. Petersburg
Ring finder JINR-LIT, Dubna
ECAL ITEP Moscow GSI Darmstadt Univ. Krakow
RPC-TOF LIP Coimbra, Univ. Santiago Univ.
Heidelberg, GSI Darmstadt, Warsaw Univ. NIPNE
Bucharest INR Moscow FZ Rossendorf IHEP
Protvino ITEP Moscow RBI Zagreb Univ. Marburg
p, K, p ID Heidelberg Univ, Warsaw Univ. Kiev
Univ. NIPNE Bucharest INR Moscow
D ? Kp(p) GSI Darmstadt, Czech Acad. Sci.,
Rez Techn. Univ. Prague
RICH IHEP Protvino GSI Darmstadt
?, ?,O PNPi St. Petersburg SPU St. Petersburg
Magnet JINR-LHE, Dubna GSI Darmstadt
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CBM Collaboration 39 institutions, 14 countries
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    
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 Obninsk State Univ. PNPI
Gatchina SINP, Moscow State Univ. St. Petersburg
Polytec. U. Spain Santiago de Compostela Univ.
  Ukraine Shevshenko Univ. , Kiev Univ. of
Kharkov
Hungaria KFKI Budapest Eötvös Univ.
Budapest Korea Korea Univ. Seoul Pusan National
Univ. Norway Univ. Bergen Poland Krakow
Univ. Warsaw Univ. Silesia Univ.
Katowice   Portugal LIP Coimbra Romania NIPNE
Bucharest
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The experimental program of CBM
Observables Penetrating probes ?, ?, ?, J/?
(vector mesons) Strangeness K, ?, ?, ?, ?,
Open charm Do, D?
Systematic investigations AA collisions from 8
to 45 (35) AGeV, Z/A0.5 (0.4) pA collisions
from 8 to 90 GeV pp 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