The heavy ion collider experiment @ LHC A L I C E

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The heavy ion collider experiment _at_ LHC A L I C E

• Ginés MARTINEZ
• for the ALICE Collaboration

Photon Group _at_ SUBATECH(IN2P3/CNRS ENM - UN)
Nantes, France
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Outlook

1. Why a Heavy Ion Experiment _at_ LHC?
2. Goals
3. Building ALICE

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The study of the Quark Gluon Plasma

Krasch QM2001
Lattice QCD calculations nf2 Tc 1738SysErr
MeV nf3 Tc 1538SysErr MeV ec 700 300 MeV

• QCD-thermodynamics
• Properties of the QGP and of the phase
  transition
• Chiral transition
• Deconfinement

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Towards QCD thermodynamics

• The TOOLS
• Heavy Ion Collisions SPS gt RHIC gt LHC
• The relation with QCD at finite temperature
• The pp pA baseline
• Equilibration
• Probes of QGP formation?
• QGP Initial conditions?

Collision dynamics
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collision dynamics
pp and pA baseline !
Sensitivity to late stages in HI collisions!
Final state probes
Penetrating probes
The QGP phase
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Why HI program _at_ LHC ?
Central collisions SPS RHIC LHC
s1/2(GeV) 17 200 5500
dNch/dy 500 700-1500 3-8 x103
e (GeV/fm3) 2.5 3.5-7.5 15-40
Vf(fm3) 103 7x103 2x104
tQGP (fm/c) lt1 1.5-4.0 4-10
t0 (fm/c) 1 0.5 lt0.2
_at_ LHC Hotter bigger - longer
J. Schukraft QM2001
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The gluon-gluon physics

• Gluon distribution in nuclei grows for small
  values of x 2pT /s1/2 and high gluon densities
  are reached .
• For high densities (rT gtgt L2QCD ) in large nuclei
  small x, the gluon distribution can be
  computed in the weak coupling method.
• The classical color field.
• A large number of gluons are freed in the early
  stage of the collision gt Equilibration

PRD10(74)1649, PRC49(94)2233, PRD49(94)3352,
PRD53(96)458, PRC56(97)2219
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Advantages of PbPb collisions _at_ LHC

• Better connection with QCD theory (via the
  asymptotically free field theory) A E
• Initial gluon multiplicity (R.Venugopalan QM01,
  PRL86(01)1717)
• Initial equilibration conditions (D. Son
  QM01,hep-ph/0009237)
• Longer lifetime of the plasma
• Ideal plasma e/ec 5 higher T
• Zero baryon density (already p/p 0.6 _at_ RHIC)
• New probes Jets, Open charm beauty,
  bottonium

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Final state probes

• Forward energy
• dN/dy
• hadron pT distribution
• Particle ratios
• Strange particles

• Multiplicity
• Energy Density
• HBT and dynamical evolution
• Freeze-out temperature
• Fluctuations
• Collective motion

• 12200 ps
• 1700 Ks
• 700 hs
• 570 p, n, p, n s
• .

-1lthlt1
PbPb _at_ 5.5A TeV
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Penetrating probes

• Real and virtual photons
• Quarkonia J/Y Y
• Open Charm Beauty
• Light vector mesons
• Jets

• Initial stage
• Thermal radiation Tini
• Colour screening of heavy quarks
• Jet-matter interaction
• Chiral transition

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Jet Matter interaction
1-3 GeV/fm
Large production of jets _at_ LHC energies 1
jet/GeV/s in the ALICE acceptance at ET 50 GeV
Dt0
B
A
Looking for Jet matter interaction

• High pT particle distributions
• Identification of jets
• Tagging with photons
• High pT particles
• Jets

g
Interference with vacuum and LPM, Jet
enhancement Ejet dependence of DE pTgt 10 20 GeV
Urs. Wiedemann QM2001 et NPB588(00)203
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Building ALICE

• Event Characterisation
• dNch/dy
• pT distribution
• Particle ratios
• Strange baryons
• Fluctuations

• Light vector mesons
• Quarkonium
• Open charm beauty
• Photon Dilepton
• Jet quenching

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dNch/dh Dh1 8000
Tracking efficiency 90 2 tracks eff. 80 Dpgt15
MeV/c

• Time Projection Chamber Main tracking
  detector of ALICE central barrel
• Inner radius Track separation
• Rin 0.8 m
• Outer radius dE/dx p resolution Rout
  2.5 m
• Large acceptance Dh lt0.9
• 200Hz rate capability
• MWPC read-out 32 m2, 40 Oc
• 5 105 pads x 500 time bins
• 60 Mbyte/evt gt DC, RoI, L3

5 m
TPC
NeCO2(10)

1. PID below 600 MeV/c
2. Low Dp tracks

Magnetic field of the L3 magnet 0.4T 5 _at_ 5
GeV/c
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The ALICE PID
Time of Flight High Momentum Particle
Identification Transition Radiation Detector

• 0.5 lt p lt 5 GeV/c
• e, p, K, p

ALICE solution
ToF prototype
Multigap Resistive Plate Chamber

• pT distributions
• Particles ratios Tfreeze-out
• Fluctuations
• Strangeness production
• Light vector mesons
• Open charm
• Jet physics

ToF

• Large acceptance
• MRPC
• s 150 ps
• p,K,p
• 0.5ltplt2.5 GeV/c

10cm
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High momentum particles

• High Momentum PID
• Hard processes
• 1 GeV/c lt p lt 5 GeV/c
• Rich-imaging technique
• Small acceptance

7x
HMPID
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Electron Identificator of ALICE

• Electron detector
• 10-3 pion rejection
• Large acceptance
• Transition Radiation Detector

• J/Y in Zero baryon density
• Open charm normalization
• J/Y source from Open Beauty
• D annihilation?
• G production
• Light vector resonances f, w

e channel
TRD
PbPb central collisions
6x
g 103 EX 3-30 KeV
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Primary and secondary Vertex Position
p
L

• Secondary vertex from hyperon decays
• Open charm beauty physics
• Tracking of low pT particles
• Improving momentum resolution
• Strangelets

W-
I T S
p-
K-
ITS

• Large acceptance
• 15000 tracks
• s100mm in rf

• 6 Silicon layers
• 2 Silicon Pixel layers
• 2 Silicon Drift layers
• 2 Silicon Strip layers

D gtKp 107 evt
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Photon detection
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• Thermal radiation
• High pt physics
• Tagged jets
• 1200 g pTgt40 GeV/c

5x
Thermal/Decay
1
PHOS
PHOS Module
5
0.1
hep-ph/9906325
pT(GeV/c)
1
2
3
4

• EM calorimeter
• PbWO4 spectrometer p0,h
• Small acceptance 0.07 DhDf/2p
• 1lt pT lt 5 GeV/c
• 5lt pT lt100 GeV/c

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Di muon channel

• Quarkonium physics
• J/Y and Y families
• 100 MeV
• 2.4 lt h lt 4.0

DiMuon

• em coin.
• Intermediate
• rapidity
• DD, BB
• production

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ALICE The result of QGP physics requirements
at LHC
PMD FMD CASTOR ZDC Trigger DAQ Offline
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Running conditions

• PbPb _at_ 5.5A TeV
• 106s per year
• 8000 Hz (L1027 cm-2s-1)
• Data rate full ALICE 50 Hz (TPC challenge)
• pp pA running
• Lighter ions _at_ higher luminosity.
• Beginning 2007

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conclusions

• HI in LHC a rigorous step towards the QGP
  physics
• Perturbative weak coupling methods
• Direct partonic probes Jets.
• The LHC HI dedicated experiment ALICE
• Penetrating and final state probes
• 884 members 28 countries 77 institutes
• Rendez-vous _at_ CERN March-April 2007

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A new research domain
Quark Matter 2002 in Nantes