Transcript Document
Bulk Properties of QCD Matter
Many thanks to organizers !
Kai Schweda, University of Heidelberg / GSI Darmstadt
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Outline
Introduction
Hadron Abundances - Tch
Collective Flow - Tfo,
Heavy Quarks - open charm and
quarkonia
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Introduction
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Kai Schweda
Quark Gluon Plasma
Source: Michael Turner, National Geographic (1996)
Quark Gluon Plasma:
(a) Deconfined and
(b) thermalized state of quarks and gluons
Study partonic EOS at RHIC and LHC
(?) Probe thermalization using heavy-quarks
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Nuclear phase diagram
Energy scan
1) Heavy quarks with ALICE at LHC:
- Study medium properties
- pQCD in hot and dense environment
2) FAIR/GSI program:
- Search for the possible phase boundary.
- Chiral symmetry
restoration
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Days, Heidelberg, 5 9 Oct, 2009
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Colliding Heavy Nuclei
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High-Energy Nuclear Collisions
Time
CYM & LGT
1) Initial condition: 2) System evolves:
3) Bulk freeze-out
PCM & clust. hadronization
-Baryon transfer
- parton/hadron expansion - hadronic dof
NFD
- ET production
- inel. interactions cease:
NFD & hadronic TM
particle ratios, Tch, mB
-Partonic dof
string & hadronic TM
PCM & hadronic TM
Plot: Steffen A. Bass, Duke University
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- elas. interactions cease
Particle spectra, Tth, <T>
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Collision Geometry
Au + Au sNN = 200 GeV
Non-central Collisions
Uncorrected
Number of participants: number of incoming nucleons in the overlap region
Number of binary collisions: number of inelastic nucleon-nucleon collisions
Charged particle multiplicity
Reaction plane: x-z plane
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collision centrality
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Hadron Abundances
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Particle Multilplicities
PHOBOS fit
HIJING BBar
Armesto et al.
AMPT
Eskola
CGC
KLN
ASW
DPMJET-III
EHNRR
at LHC, dN/dh 1000 3000
1
1 dE
estimate energy density Bj R 2 dyT
0
PHOBOS compilation: W. Busza, SQM07.
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Theory points: HI at LHC – last call for predictions, CERN, May 2007.
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EoS from Lattice QCD
1) Large increase in !
SPS
RHIC
LHC ?
Large increase in Ndof:
Hadrons vs. partons
2) TC ~ 160 MeV
3) Boxes indicate max. initial
temperatures
Longest expansion
duration at LHC
Expect large partonic
collectivity at LHC
Z. Fodor et al, JHEP 0203:014(02)
C.R. Allton et al, hep-lat/0204010
F. Karsch, Nucl. Phys. A698, 199c(02).
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HI - Collision History
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Tc(ritical): quarks and gluon hadrons, Tc(ritical) = 160 MeV
Tch(emical): hadron abundancies freeze out
Tfo: particle spectra freeze out
Plot: R. Stock, arXiv:0807.1610 [nucl-ex].
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Solar Spectrum
Wavelength and Intensity solely determined by temperature Tsolar = 5500 °C
(at the sun’s surface)
Graphik: Max-Plack-Institut für Plasmaphysik
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Wie heiss ist die Quelle ?
1000
Lichtquelle Teilchenquelle
N
Teilchenhäufigkeit
Häufigkeit von Teilchen am
K+
100.
besten beschrieben durch
L
K0
K- h
N
10.0
T = 2 000 000 000 000 C
X
f
L
= 2 Trillionen C
W
1.0
100 000 mal heisser als
im Innern der Sonne !
X
W
0.1
0
0.4
0.8
1.2
1.6
E = mc2 (GeV)
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Chemical Freeze-out Model
Hadron resonance ideal gas
Refs. J.Rafelski PLB(1991)333
P. Braun-Munzinger et al., nucl-th/0304013
Density of particle i
Qi : 1 for u and d, -1 for u and d
si : 1 for s, -1 for s
gi : spin-isospin freedom
mi : particle mass
mB = 3mq
mS = mq-ms
Tch
mq
ms
V
gs
: Chemical freeze-out temperature
: light-quark chemical potential
: strange-quark chemical potential
: volume term, drops out for ratios!
: strangeness under-saturation factor
All resonances and unstable particles are decayed
Compare particle ratios to experimental data
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Hadron Yield Ratios
1) At RHIC:
Tch = 160 ± 10 MeV
mB = 25 ± 5 MeV
2) gS = 1.
The hadronic
system is
thermalized at RHIC.
3) Short-lived resonances
show deviations.
There is life after
chemical freeze-out.
RHIC white papers - 2005, Nucl. Phys. A757, STAR: p102; PHENIX: p184;
Statistical Model calculations: P. Braun-Munzinger et al. nucl-th/0304013.
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Chemical Freeze-Out vs Energy
With increasing energy:
•
Tch increases and saturates
at Tch = 160 MeV
•
Coincides with Hagedorn
temperature
•
Coincides with early lattice results
limiting temperature for
hadrons, Tch 160 MeV !
mB decreases, mB = 1MeV at LHC
Nearly net-baryon free !
A. Andronic et al., NPA 772 (2006) 167.
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QCD Phase Diagram
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
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Baryon Ratios
With increasing energy:
•
Baryon ratios approach unity
•
At LHC, pbar / p 0.95
with increasing
collision energy,
production of matter
and anti-matter gets
closer
Compilation: N. Xu
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‘Elementary’ p+p Collisions
Low multiplicities
use canonical ensemble:
Strangeness locally
conserved!
particle yields are well
reproduced
Strangeness not
equilibrated ! (gs = 0.5)
Statistical Model Fit: F. Becattini and U. Heinz, Z. Phys. C 76, 269 (1997).
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HI - Collision History
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Tc(ritical): quarks and gluon hadrons, Tc(ritical) = 160 MeV
Tch(emical): hadron abundancies freeze out, Tch(emical) = 160 MeV
Tfo: particle spectra freeze out
Plot: R. Stock, arXiv:0807.1610 [nucl-ex].
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Collective Flow
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Pressure, Flow, …
Thermodynamic identity
– entropy
p – pressure
U – energy
V – volume
= kBT, thermal energy per dof
d dU pdV
In A+A collisions, interactions among constituents
and density distribution lead to:
pressure gradient collective flow
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number of degrees of freedom (dof)
Equation of State (EOS)
cumulative – partonic + hadronic
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Momentum Distributions*
2
dN
[(GeV/c)-1 ]
2 dpT dy
K (dE/dx)
p
K (dE/dx)
Tth=107±8 [MeV]
<t>=0.55±0.08 [c]
n=0.65±0.09
2/dof=106/90
solid lines: fit range
p
L
•
Typical mass ordering in inverse slope
from light to heavier L
•
Two-parameter fit describes yields of
, K, p, L
•
Tth = 90 10 MeV
•
<t> = 0.55 0.08 c
Disentangle
collective motion from thermal
L
random walk
pT [GeV/c]
*Au+Au @130 GeV, STAR
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(anti-)Protons From RHIC
More central collisions
Au+Au@130GeV
mT
pT2 mass 2
Centrality dependence:
- spectra at low momentum de-populated, become flatter at larger momentum
stronger collective flow in more central coll.! STAR: Phys. Rev. C70, 041901(R).
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Thermal Model + Radial Flow
Fit
Source is assumed to be:
– in local thermal equilibration: Tfo
– boosted in transverse radial direction: r = f(s)
boosted
E.Schnedermann, J.Sollfrank, and U.Heinz, Phys. Rev. C48, 2462(1993)
d 3N
(u m p m )/T fo
E 3 e
pd m
dp
random
m coshr p sinh r
R
dN
0 rdrmT K1 T
I0 T
mT dmT
Tfo Tfo
r tanh1 T
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r
T S
R
0.5, 1, 2
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D-meson collective flow
Large collective flow
velocity
Spectrum moves to
larger momentum
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HI - Collision History
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Tc(ritical): quarks and gluon hadrons, Tc(ritical) = 160 MeV
Tch(emical): hadron abundancies freeze out, Tch(emical) = 160 MeV
Tfo: particle spectra freeze out, Tfo 100 MeV :, K, p
Plot: R. Stock, arXiv:0807.1610 [nucl-ex].
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Kinetic Freeze-out at RHIC
1) Multi-strange hadrons f
and W freeze-out earlier
than (, K, p)
Collectivity prior to
hadronization
STAR Preliminary
2) Sudden single freeze-out*:
Resonance decays lower Tfo
for (, K, p)
Collectivity prior to
hadronization
Partonic
Collectivity ?
STAR Data: Nucl. Phys. A757, (2005 102),
*A. Baran, W. Broniowski and W. Florkowski, Acta. Phys. Polon. B 35 (2004) 779.
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Anisotropy Parameter v2
coordinate-space-anisotropy
momentum-space-anisotropy
y
x
y2 x2
2
y x2
py
v 2 cos2 , tan ( )
px
1
Initial/final conditions, EoS, degrees of freedom
v2 in the Low-pT Region
- v2 approx. linear in pT, mass ordering from light to heavier L
characteristic of hydrodynamic flow !
sensitive to equation of state
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Non-ideal Hydro-dynamics
h
s
finite shear viscosity h reduces elliptic flow
many caveats, e.g.:
- initial eccentricity (Glauber, CGC, …)
- equation of state
- hadronic contribution to h/s
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String theory
predicts:
h/s > 1/4
M.Luzum and R. Romatschke, PRC 78 034915 (2008); P. Romatschke, arXiv:0902.3663.
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Elliptic Flow vs Collision Energy
Glauber initial conditions
Centrality dependence:
- initial eccentricity
- overlap area S
QuickTime™ and a
decompressor
are needed to see this picture.
Collision energy dep.:
- multiplicity density dNch/dy
in central collisions
at RHIC, hydro-limit
seems reached !
NA49, Phys. Rev. C68, 034903 (2003);
STAR, Phys. Rev. C66, 034904 (2002);
Hydro-calcs.: P. Kolb, J. Sollfrank, and U. Heinz, Phys. Rev.C62, 054909 (2000).
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v2 of f and multi-strange W
Strange-quark flow - partonic collectivity at RHIC !
QM05 conference: M. Oldenburg; nucl-ex/0510026.
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Collectivity, Deconfinement at
RHIC
- v2, spectra of light hadrons
and multi-strange hadrons
- scaling with the number of
constituent quarks
At RHIC, it seems we have:
Partonic Collectivity
Deconfinement
Thermalization ?
PHENIX: PRL91, 182301(03)
STAR: PRL92, 052302(04)
S. Voloshin, NPA715, 379(03)
Models: Greco et al, PRC68, 034904(03)
X. Dong, et al., Phys. Lett. B597, 328(04).
….
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Collectivity Energy Dependence
Collectivity parameters <T>
and <v2> increase with
collision energy
strong collective
expansion at RHIC !
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
<T>RHIC 0.6
expect strong partonic
expansion at LHC,
<T>LHC 0.8, Tfo Tch
K.S., ISMD07, arXiv:0801.1436 [nucl-ex].
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Partonic Collectivity at RHIC
1) Copiously produced hadrons freeze-out ,K,p:
Tfo = 100 MeV,
T = 0.6 (c) > T(SPS)
2) Multi-strange hadrons freeze-out:
Tfo = 160-170 MeV (~ Tch), T = 0.4 (c)
3) Multi-strange v2:
f and multi-strange hadrons X and W do flow!
4) Model - dependent h/s: (0?),1 - 10 x 1/4
Deconfinement &
Partonic (u,d,s) Collectivity !
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Heavy Quarks
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Kai Schweda
Heavy flavor: a unique probe
mc,b >> LQCD : new scale
mc,b const., mu,d,s ≠ const.
Q2
• initial conditions:
cc bb
test pQCD, mR, mF
probe gluon distribution
• early partonic stage:
diffusion (g), drag (), flow
probe thermalization
X. Zhu, M. Bleicher, S.L. Huang, K.S., H. Stöcker,
N. Xu, and P. Zhuang, PLB 647 (2007) 366.
time
• hadronization:
chiral symmetry restoration
confinement
statistical coalescence
J/ enhancement / suppression
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Limitations in PDFs
Most charm created from
gluons, e.g. g+g c + cbar
increasing uncertainties in gluon
distribution at smaller Bjorken x:
Assume y=0, pT=0, x1=x2
2 x mcharm 3 GeV
RHIC (s=0.2TeV): x = 0.015
LHC (s=14TeV): x = 2x10-4
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Heavy Quark Production
Heavy-quark
production at
LHC,
compared to
RHIC expect
factors
Charm 10
Beauty 100
(i) Heavy-quarks abundantly produced at LHC energies !
(ii) Large theoretical uncertainties energy scan (LHC,FAIR) will help !
Plots: R. Vogt,Eur. Phys. J. C, s10052-008-0809-x (2008).
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Heavy quark Correlations
PYTHIA: p + p @ 14 TeV
c-cbar mesons are correlated
•
Pair creation: back to back
•
Gluon splitting: forward
•
Flavor excitation: flat
Exhibits strong correlations !
Baseline at zero:
clear measure of
vanishing correlations !
probe thermalization
among partons !
X. Zhu, M. Bleicher, S.L. Huang, K.S., H. Stöcker,
N. Xu, and P. Zhuang, PLB 647 (2007) 366.
G. Tsildeakis, H. Appelshäuser, K.S., J. Stachel, arXiv: 0908.0427.
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How to measure HeavyQuark Production
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
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e.g., D0, c = 123 mm
displaced decay vertex is signature of heavy-quark decay
need precise pointing to collision vertex
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Heavy Flavor production at RHIC
large discrepancy between
STAR and PHENIX:
factor > 2 (!)
need Si-vertex upgrades
(> 2011)
large theoretical
uncertainties (factor > 10)
Measure charm production
at RHIC, LHC, FAIR and
provide input to theory:
- gluon distribution,
- scales mR, mF
Plot: J. Dunlop (STAR), QM2009, Open Heavy-flavor in heavy-ion collisions,
Calcs: R. Vogt,Eur. Phys. J. C, s10052-008-0809-x (2008),
M. Cacciari, 417th Heraeus Seminar, Bad Honnef (2008).
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Where does all the charm
go?
J
Lc
Ds
D
D0
Total charm cross section: open charm hadrons,
e.g. D0, D*, Lc, … or c,b e(m) + X
Hidden-charm mesons, e.g. J/ carry ~ 1 % of total charm
Statistics plot: H. Yang and Y. Wang, U Heidelberg.
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D0 + + K- Reconstruction
+
D 0,
c = 123 mm
K-
Plot: A. Shabetai
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Open Charm Performance
Measure secondary decay vertex
Direct reconstruction of D0
address heavy-quark production
with 1st year of data taking
Many other channels, e.g. D+, D*
Also: single-electrons from heavy-flavor
decays
ALICE: PPR.vol.II, J. Phys. G 32 (2006) 1295.
Simulation: 109 p+p, 108 p+Pb, 107 Pb+Pb collisions
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D* meson Identification
D*+ D0 + +
Identify D*+
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
through
M[D*+ - D0]
Subtract resonance
decay to D0
Two different
methods to address
total charm
production
D*± analysis: Yifei Wang, Ph.D. thesis, University of Heidelberg, in preparation.
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Viele neue interessante Signale in ALICE bei LHC:
z.B.
Hadronen mit schweren Quarks
(charm und beauty)
D0, D+, D*, Ds, J/ ’, Lc Lb
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Quarkonia
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Charmonium
Bound state of charm- and anti-charm quark
Hidden-charm meson
mJ/ = 3.1 GeV, rJ/ = 0.45 fm, mJ/' = 3.6 GeV, JP = 1- states
Minimum formation time = rJ/ / c = 0.45 fm
Charm-quark production at time scale tc~ 1/2mc 0.08 fm
Separation between initial production and hadronization (factorization)
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Debye Screening
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Quarkonia as a Thermometer
Check for melting of bottomonium (b-bbar)
at Tdeconfined 2 Tc
Check for melting of charmonium (c-cbar)
at Tdeconfined 1.2 Tc
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Absolute numbers model-dependent Tfo:
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J/ Production
P. Braun-Munzinger and J. Stachel, Nature 448 (2007) 302.
suppression,
compared to
scaled p+p
(SPS)
regeneration,
enhancement
Low energy (SPS):
few ccbar quarks in the system suppression of J/
High energy (LHC):
many ccbar pairs in the system enhancement of J/
Signal of de-confinement + thermalization of light quarks !
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Statistical Hadronization of Charm
large charm production at LHC
strong generation of J/
cc
striking centrality dependence
Signature for QGP
formation !
Initial conditions at LHC ?
Need to measure total
charm production in PbPb !
Assumes kinetic
equilbration of charm !
A. Andronic, P. Braun-Munzinger, K. Redlich, J. Stachel, Phys. Lett. B 652 (2007) 259.
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Charmonium production
In central Pb+Pb collisions at
top SPS energy:
J/’ to J/ ratio approaches
thermal limit
Indicates kinetic equilibration
of charm
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Examples of the ALICE physics potential
- Open charm: D0 K- + +
(already shown)
- Quarkonia: J/,
- Global event properties
Will be addressed in first year of pp collisions
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First Physics with ALICE
Results from simulations
1 day of data taking
Address:
- multiplicity
- mean transverse momentum
- hadro-chemistry
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Charmonia via Di-Electron
Measurement
• electron ID with TPC and TRD
• expect 2500 mesons per Pb+Pb year
with good mass resolution and S/B
Simulation: pp coll.
c1 c2
J/
Simulation: 2·108 central PbPb collisions
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Heavy Flavor in Muon Channel
•
muon channel: J/, m+m- (2.5 <h<
4)
60000 J/ and 2000
•
initial sample sufficient to study
production rates of J/ and
states in muon channel
J/
bm
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LHC: Schedule
1st pp collisions
very short run at 900 GeV
Nov 2009:
Long run of pp collisions at 7- 10 TeV
end of 2010:
3 - 4 weeks Pb+Pb collisions
at 2.8 - 3.9 TeV
*short technical stop
over Christmas period
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ALICE Ready for Physics !
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