30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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ALICE at LHC
New states of matter ? (QGP, wQGP, sQGP, bsQGP, CGC,…)
New probes“LHC not relevant for the search of the critical point” Marek Gazdzicki
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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SPS: ”New State of Matter created at CERN” (10 Feb. 2000)
7 dedicated experiments (NAxx, WAyy)
Compelling evidence for the existence of a new state of matter (3.2
GeV/fm3]>c, strangeness enhancement, J/ψ suppression, direct thermal photon radiation,…)
Interpretation in terms of QGP formation not unique
Pb+Pb √sNN = 17.3 GeV NA 49
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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RHIC: “The discovery of the QGP at RHIC” (M. Gyulassy QM 2004)
4 multipurpose experiments (BRAHMS, PHENIX, PHOBOS, STAR)
Empirical lines of evidence: Energy density (5 GeV/fm3)
well beyond critical value Large elliptic flow: early
collective behavior at partonic level
Jet quenching, mono jets: absorption of partons in a color dense opaque medium
dA control experiment Interpreted in terms of a strongly
coupled QGP and a new QCD state (?) Color Glass Condensate
Au+Au √sNN = 200 GeVSTAR
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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LHC: “The closest approximation of the Big Bang”
One heavy ion experiment, ALICE
In 04/2007, LHC will deliver first pp at 14 TeV collisions,
and soon after PbPb collisions at √sNN= 5.5 TeV.
“It is dangerous to make predictions, especially about the future."
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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What will be new at LHC
SPS RHIC LHC
√sNN (GeV) 17 200
dNch/dy 500 850
0QGP (fm/c) 1 0.2
T/Tc 1.1 1.9
(GeV/fm3) 3 5
QGP (fm/c) ≤2 2-4
f (fm/c) ~10 20-30
Vf(fm3) few 103 few 104
few 105 bigger
5500 X 28
1000-4000 ?
0.1 faster
3.0-4.2 hotter
15-60 denser
≥10longer
30-40
“The biggest step in energy in the history of heavy-ion collisions”
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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Formation of the real vacuum of QCD
Weakly interacting gas of mass less quarks (3 flavors) and gluons with restored Chiral symmetry
mu= md = ms
mu = md
mu = md ; ms mu,d
HQ suppressed exp(-mc,b,t/T)
s(T)=4/(18log(5T/Tc))
RHIC
SPS
LHC
Not yet a StefanBoltzmann gas
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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A new kinematical regime
x<<1 Determines the properties of
the medium (QS=0.2A1/6√s= 2.7 GeV)
The QGP at LHC might evolve from a Color Glass Condensate in the initial state of the collision
J/ψ
ALICE PPR CERN/LHCC 2003-049²
10-6 10-4 10-2 100
x
108
106
104
102
100
Q2 (
GeV
2)
100 GeV
“LHC: The color glass machine”L. McLerran
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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A new kinematical regime
Q >> 1 Determines the probe of the
medium Q >> QCD, T (, r ~1/Q) ;
pt > 2 GeV/c
J/ψ
ALICE PPR CERN/LHCC 2003-049²
10-6 10-4 10-2 100
x
108
106
104
102
100
Q2 (
GeV
2)
100 GeV
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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Hard probes Particle production dominated
by hard processes Heavy quarks and weakly
interacting probes become accessible
Happen at t=0 → initial stage of the collision
Have a large virtuality → short formation time
Probe matter at very early
times → QGP
Can be calculated by pQCD → predictions
LHC
RHICSPS
(h++h-)/2
0
17 GeV
200 GeV
5500 GeV=√s
LO p+p y=0
LHC:hard/total = 98% (50% at RHIC)
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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Dynamics of hadronisation : in vacuum
The medium modifies the vacuum dynamics Modifications are imprinted in the hadronic final state
ET
hadronic final state
Lhadr ~ ET/Q2hadr
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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Dynamics of hadronisation: in medium
The radiated energy (E) depends on the properties of the medium (the transport coefficient q) The competition between thermalisation (E=E) and hadronisation depends on the hard parton transverse energy.
ET
hadronic final state
Lhadr ~ ET/Q2hadr
E Ltherm ~ √(ET/q )^
^
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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Dynamics of hadronisation: in medium
Ltherm< Lhadr < Lmedium
The hard parton is thermalised in the heat bath Bulk properties of the medium from low ph
t ( ≤ 2 GeV/c) hadrons, leptons, photons
ET
E ~ ET
Experimental requirements: low pt threshold
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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Bulk properties of the LHC medium Monotonic extrapolation from RHIC but changes in
Expansion dynamics and (elliptic flow, transverse volume, event by event fluctuations, …)
Freeze out (temperature, charm, …) Thermal photons (real & virtual)
150
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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Dynamics of hadronisation: in medium
Ltherm~ Lhadr ~ Lmedium
The medium is a tool to modify the hadronisation process Dynamics of hadronisation (ph
t ~2-7 GeV/c)
ET
hadronic final state
Lhadr ~ ET/Q2hadr
E Ltherm ~ √(ET/q )^
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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Medium modified fragmentation
Fragmentation, recombination ?
Experimental requirements: PID up to ~ 10 GeV/c
p/
Pt[GeV/c]
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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Dynamics of hadronisation: in medium
Ltherm> Lhadr > Lmedium The parton looses additional energy (qL2) The multiplicity, transverse momentum of the shower
broadens (qL) Leading hadron
ET
hadronic final state
E Ltherm ~ √(ET/q )^
^
^
xET
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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Leading hadron (qL2)
Probe the reduced energy of the parton with the reduced energy of the leading hadron.
… But surface emission limits the sensitivity to the medium properties
Eskola, Honkanen, Salgado, Wiedemann Nucl Phys A, hep-ph/0406319
Experimental requirements: high pt
^
q=5 GeV2/fm^
q=10 GeV2/fm^
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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Mass and color charge dependence
Egluon Equark,m0 Equark,m0
Experimental requirements: high pt electrons, vertexing
Armesto, Dainese, Salgado, Wiedemann hep-ph/0501225
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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Jet heating (qL)
At LHC jets can be reconstructed in the HI environment The measurement of the jet structure provides a better
sensitivity to the medium properties
^
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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Jet heating
Sensitivity of jet energy distribution weak Broadening of kt
Modified longitudinal fragmentation function: (Z)-jet tagging
Salgado, Wiedemann, hep-ph/0310079
. kt
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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-jet tagging
Pb+Pb 40GeV → -jetR=0.3; pt> 2 GeV/c
Ejet/E xT=pT/E
RAA
Experimental requirements: jet calorimetry, low xt hadrons, high pt , e
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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1+2 experiments at the LHCATLASCMSALICE
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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ALICE Physics Program
Deconfinement: charmonium and bottomonium spectroscopy
Energy loss of partons in quark gluon plasma: jet quenching high pt spectra open charm and open beauty
Chiral symmetry restoration: neutral to charged ratios resonance decays
Fluctuation phenomena - critical behavior: event-by-event (√N) particle composition and spectra
pp collisions in a new energy domain
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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Heavy ion experiment at LHC
ALICE will meet the challenge to measure flavor content and phase-space distribution event-by-event: Most (2 * 1.8 units ) of the hadrons (dE/dx + ToF), leptons
(dE/dx, transition radiation, magnetic analysis) and photons (high resolution EM calorimetry);
Track and identify from very low (< 100 MeV/c; soft processes) up to very high pt (>100 GeV/c; hard processes);
Identify short lived particles (hyperons, D/B meson) through secondary vertex detection;
Identify jets;
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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Alice uses ~all known techniques!
0 1 2 3 4 5 p (GeV/c)
1 10 100 p (GeV/c)
TRD e / PHOS /0
TPC + ITS (dE/dx)
/K
/K
/K
K/p
K/p
K/p
e /
e /
HMPID (RICH)
TOF
Aerogel Cherenkov 10 GeV/c
ALICE PID
EMCAL
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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Jet Phase Space
0 1 2 10 100
pt (GeV/c)
Bulk properties
Hard processesModified by the medium
T=QCD Qs
ALICE Tracking & PID
Jets from Correlations and Leading Particles
Reconstructed Jets
Mini-jets 100/event 1/event 100K/year
Jet physics will dominate the LHC heavy-ion program, ALICE will be the main contender of the race for jet quenching
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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ALICE
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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The ALICE program in 2007 on wards
The first 15 minutes; Lint=1b-1
Event multiplicity, low pt hadronic spectra, particle ratios
The first month; Lint=0.1-1nb-1
Rare high pt processes: jets, D,B, quarkonia, photons, electrons
The following years: pA, A scan, E scan
PbPb = 8barn; LPbPb 1027cm-2s-1; t0=04/2007
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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ALICE: the dedicated HI experiment
Solenoid magnet 0.5 T
Central tracking system:• ITS •TPC• TRD• TOF
MUON Spectrometer:• absorbers• tracking stations• trigger chambers• dipole
Specialized detectors:• HMPID• PHOS
Forward detectors:• PMD• FMD, T0, V0, ZDC
Cosmic rays trigger
30 March -3 April 2005 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement
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Proposed ALICE EMCAL
EM Sampling Calorimeter (STAR Design)
Pb-scintillator linear response -0.7 < < 0.7 /3 < <
Energy resolution ~15%/√E