1. The heavy ion collider experiment @ LHC A L I C E
Ginés MARTINEZ#
for the ALICE Collaboration
#Photon SUBATECH(IN2P3/CNRS – ENM - UN) Nantes, France
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2. Rencontres de Moriond March 17-24 2001
Outlook
Why a Heavy Ion LHC?
Goals
Building ALICE
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3. The study of the Quark Gluon Plasma
Krasch QM2001
Lattice QCD calculations
nf=2 Tc = 173±8±SysErr MeV
nf=3 Tc = 153±8±SysErr MeV
ec= 700 ± 300 MeV
QCD-thermodynamics
Properties of the QGP and of the phase transition:
Chiral transition
Deconfinement
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4. Towards QCD thermodynamics
The TOOLS:
Heavy Ion Collisions: SPS => RHIC => 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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5. collision dynamics p+p and p+A baseline ! Final state probes
Sensitivity to late stages in HI collisions!
p+p and p+A
baseline !
Final state
probes
Penetrating
probes
The QGP phase
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6. Rencontres de Moriond March 17-24 2001
Why HI LHC ?
Central collisions
SPS
RHIC
LHC
s1/2(GeV) 17
200
5500
dNch/dy
500
3-8 x103
e (GeV/fm3)
2.5
15-40
Vf(fm3)
103
7x103
2x104
tQGP (fm/c)
<1
4-10
t0 (fm/c) ~1
~0.5
<0.2
@ LHC : Hotter – bigger - longer
J. Schukraft QM2001
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7. 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 >> 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 => Equilibration
PRD10(74)1649, PRC49(94)2233, PRD49(94)3352, PRD53(96)458, PRC56(97)2219
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8. Advantages of Pb+Pb collisions @ 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/ )
Longer lifetime of the plasma
Ideal plasma : e/ec ~ 5 : higher T
Zero baryon density (already p/p ~ RHIC)
New probes : Jets, Open charm & beauty, bottonium
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9. Rencontres de Moriond March 17-24 2001
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 p’s
1700 K’s
700 h’s
570 p, n, p, n ‘s ….
-1<h<1
5.5A TeV
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10. Rencontres de Moriond March 17-24 2001
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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11. Jet Matter interaction
1-3 GeV/fm#
Large production of 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
pT> 10 – 20 GeV
Urs. Wiedemann QM2001 et NPB588(00)203
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12. Rencontres de Moriond March 17-24 2001
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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13. Rencontres de Moriond March 17-24 2001
dNch/dh Dh=1~ 8000
Tracking efficiency ~90%
2 tracks eff. 80% Dp>15 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 <0.9
200Hz rate capability
MWPC read-out 32 m2, 40% Oc
5 105 pads x 500 time bins
60 Mbyte/evt => DC, RoI, L3 …
5 m
TPC
Ne+CO2(10%)
PID below ~600 MeV/c
Low Dp tracks
#Magnetic field of the L3 magnet 0.4T
5 GeV/c
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14. Rencontres de Moriond March 17-24 2001
The ALICE PID
Time of Flight
High Momentum Particle Identification
Transition Radiation Detector
0.5 < p < 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
0.5<p<2.5 GeV/c
10cm
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15. High momentum particles
High Momentum PID:
Hard processes
1 GeV/c < p < 5 GeV/c
Rich-imaging technique
Small acceptance 7x
HMPID
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16. Electron Identificator of ALICE
J/Y in Zero baryon density
Open charm normalization
J/Y source from Open Beauty
D annihilation?
G production
Light vector resonances: f, w
Electron detector
10-3 pion rejection
Large acceptance
Transition Radiation Detector e
channel
TRD
Pb+Pb central collisions 6x
g ~ 103
EX ~ 3-30 KeV
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17. Primary and secondary Vertex Position
Secondary vertex from hyperon decays
Open charm & beauty physics
Tracking of low pT particles
Improving momentum resolution
Strangelets L W- I T S p- K-
ITS
Large acceptance
15000 tracks
s~100mm in rf
6 Silicon layers:
2 Silicon Pixel layers
2 Silicon Drift layers
2 Silicon Strip layers
D =>Kp
107 evt
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18. Rencontres de Moriond March 17-24 2001
Photon detection 10
Thermal radiation
High pt physics
Tagged jets
1200 g pT>40 GeV/c 5x
Thermal/Decay 1
PHOS
0.1 5%
PHOS Module
hep-ph/ 1 2 3 4
pT(GeV/c)
EM calorimeter
PbWO4: spectrometer: p0,h
Small acceptance 0.07 DhDf/2p
1< pT < 5 GeV/c
5< pT <100 GeV/c
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19. Rencontres de Moriond March 17-24 2001
Di muon channel
Quarkonium physics:
J/Y and Y families
~ 100 MeV
2.4 < h < 4.0
DiMuon
em coin.:
Intermediate
rapidity
DD, BB
production
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20. ALICE = The result of QGP physics requirements at LHC+
PMD
FMD
CASTOR
ZDC
Trigger
DAQ
Offline
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21. Rencontres de Moriond March 17-24 2001
Running conditions
5.5A TeV
106s per year
8000 Hz (L=1027 cm-2s-1)
Data rate full ALICE 50 Hz (TPC challenge)
pp & pA running
Lighter higher luminosity.
Beginning 2007
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22. Rencontres de Moriond March 17-24 2001
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
CERN March-April 2007
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23. Rencontres de Moriond March 17-24 2001
A new research domain
Quark Matter
2002 in
Nantes
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