Perspectives for Heavy Ion Reactions At FAIR

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Perspectives for Heavy Ion ReactionsAt FAIR
2nd Swedish Workshop on FAIR Physics, Lund, 13.
September 2005
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What the accelerator will give us
SIS 100/300

• Heavy-ion beams up to 35 AGeV
• Light-ion beams up to 45 AGeV
• p beam up to 90 GeV
• Intensity 109 / s
• High availability

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Phases of strongly interacting matter
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Cold and dense matter in neutron stars
Strangeness" of dense matter ? In-medium
properties of hadrons ? Compressibility of
nuclear matter? Deconfinement at high baryon
densities ?
F. Weber J.Phys. G27 (2001) 465
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Mapping the QCD phase diagram

• at high collision energies crossover hadron gas
  ? QGP (top SPS, RHIC, LHC)
• lower energies 1st order phase transition
• separated by critical point

• Freeze-out points on smooth curve
• Close to phase border from top SPS on
• Strongly interacting hadronic phase at lower
  energies (?)

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The critical point in lattice QCD
maximal baryon number susceptibility at TC for
?q TC (?B ? 500 MeV) ? baryon number density
fluctuations
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Trajectories of heavy ion collisions

• 3-fluid hydrodynamics with hadron gas EOS
• Phase boundary is reached already with 10 AGeV
• 30 AGeV hits critical point

V.Toneev, Y. Ivanov et al., nucl-th/0309008
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Existing data Onset of deconfinement
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, onset at 30 AGeV
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Critical fluctuations
Dynamical fluctuations in K/p increase towards
lower collision energies
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J/? suppression at top SPS
NA50, QM 2005

• "anomalous" suppression observed at top SPS
  (NA50)
• indication for QGP (?)
• no data at lower energies available !
• can onset be seen?

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Probing the dense fireball
using penetrating probes short lived vector
mesons ? ee- pairs
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Low-mass ee- spectroscopy
No data below 40 AGeV Maximum effect at highest
baronic density need high precision, high
statistics data
Excess of low-mass pairs over hadronic cocktail
(CERES) In-medium modification of ? ? Low
statistics and resolution
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Open charm near threshold
W. Cassing, E. Bratkovskaya, A. Sibirtsev, Nucl.
Phys. A 691 (2001) 745

• extremely low multiplicity
• sensitive to production mechanism
• expected to change mass in medium
• no data in HI collisions!

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Charm in dense matter
D meson masses are expected to drop in dense
environment should have strong effect on
production yield
Mishra et al, nucl-th/0308082
Cassing et al, Nucl. Phys. A 691 (2001) 753
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Physics topics
?
!
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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Diagnostic probes
Urqmd, UU, 23 AGeV
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Why we go back to intermediate energies

• Existing data (AGS, RHIC) do not allow an
  unambiguous interpretation of the collision
  dynamics
• Go on step beyond with a next-generation
  experiment (and accelerator)
• highest interaction rates ? access to rare probes
• high availability ? systematic studies (collision
  energy, system size)
• large acceptance ? complete rapidity coverage
• exploit newest detector technologies
• measure hadronic as well as leptonic observables

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CBM 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
large and uniform acceptance
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CBM 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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Extreme conditions
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 (? 50 ?m)
• ? identification of electrons and hadrons

Simultaneous measurement of all observables is
not possible optimized beam intensities and
dedicated subdetectors
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Unprecedented requirements

• Challenges for detectors and readout
• high rate capability
• fast detector response and readout
• radiation hardness
• high precision
• low material budget
• No existing technology meeets the requirements
• RD is needed and ongoing, e.g.
• radiation hard silicon tracker
• fast gaseous detectors (TRD, RPC)

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The Silicon Tracking System
"minimal setup" 3 pixel stations 4 strip
stations
momentum resolution lt 1
alternative options (including hybrid pixels for
track seed) under investigation
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RD Silicon pixel detectors
Close to target (5 cm), vertex resolution 50 µm
needed Key issues Material budget, resolution,
speed, radiation tolerance
Mimosa IV

• RD on MAPS at IReS Strasbourg
• thickness lt 100 µm
• resolution 3 µm
• readout frame several µs
• rad. tolerance

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RD on fast TRD
Key issues Fast ? Thin radiator and converter,
high rates

• Developments by GSI, Bucharest, Dubna
• First beam test of prototypes at GSI in summer
  2004
• Different readouts (MWPC, GEM)
• Encouraging results Stable up to 70 / 100 kHz/cm2

MWPC (Dubna)
GEM (Dubna)
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RD on large-area timing RPCs

• Design goals
• Time resolution 80 ps
• Rate capability up to 20 kHz/cm2
• Efficiency gt 95
• Large area ? 100 m2
• Long term stability

• RD in GSI/Heidelberg, Coimbra
• prototype tests encouraging
• alternative options (window glass, ceramic)
  under investigation

Prototype with plastic electrodes (109 Ocm)
RPC prototype with phosphate glass
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Benchmark observable D mesons
Simulation STS only (no PID) with MAPS full
track reconstruction, secondary vertex
determination
Challenge Implementation of secondary vertex cut
in online event selection (reduction 1000
needed)
1011 events
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Self-triggered FEE / data-push DAQ
Detector
Self-triggered front-end Autonomous hit detection
fclock
FEE
No dedicated trigger connectivity All detectors
can contribute to L1
Cave
Shack
DAQ
Large buffer depth available System is
throughput-limited and not latency-limited
High bandwidth
Modular design Few multi-purpose rather many
special-purpose modules
Special hardware
archive rate few GByte/s
Archive
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The CBM Physics Working Group
established June 2005
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Summary

• FAIR will offer the opportunity for an exiting
  physics programme for heavy-ion collisions from
  2014 on
• Experimental conditions (beam intensity, machine
  availablity) will be unprecedented
• The physics will cover
• hadrons in dense matter
• deconfinement at high net baryon density
• critical point
• The experimental conditions are extreme. RD on
  fast, radiation hard and precise detectors is
  under way
• Feasibility studies, event reconstruction and
  development of analysis software are advancing

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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