Transcript Document 7316678

Heavy-Ion Physics @ LHC
 ~1100 participants:

1000 ALICE

60 CMS
 Program

25 ATLAS
 Detectors  26 experimental contributions QM04
 6 oral: P. Glaessel, V. Manzari, A.
 Observables Vestbo, H. Takai, B. Wyslouch, S. Blyth.
 20 posters: Spectra 23, HBT 1, High
pT 17, 20, 21, Flavor 18, 19, 23, Instr.
1, 2, 7, 8, 10, 12, 14, 15, 16, 17, 22,
30.
QM2004
Yves Schutz
1
The LHC facility
 Running conditions:
√sNN
(TeV)
L0
<L>/L0
(cm-2s-1)
(%)
pp
14.0
1034*
PbPb
5.5
1027
Collision
system
April 2007
End 2007
Early 2008
70-50
*Lmax(ALICE) = 1031
Run time
(s/year)
sgeom
(b)
107
0.07
106 * *
7.7
** Lint(ALICE) ~ 0.7 nb-1/year
 + other collision systems: pA, lighter
ions (Sn, Kr, Ar, O) & energies (pp @ 5.5 TeV).
QM2004
Yves Schutz
2
Novel aspects:
Qualitatively new regime
108


nuclear shadowing,
high-density saturated
gluon distribution.
 Larger saturation scale
(QS=0.2A1/6√sd= 2.7 GeV):
particle production
dominated by the
staturation region.
106
M2 (GeV2)
 Probe initial partonic state
in a novel Bjorken-x range
(10-3-10-5):
104
10 GeV
102
J/ψ
100
10-6
10-4
ALICE PPR CERN/LHCC 2003-049
QM2004
Yves Schutz
x
10-2
100
3
Novel aspects:
Qualitatively new regime
 Hard processes
contribute significantly
to the total AA crosssection (σhard/σtot = 98%):


LO p+p y=0
(h++h-)/2
p0
Bulk properties
dominated by hard
processes;
Very hard probes are
abundantly produced.
=
5500 GeV
200 GeV
17 GeV
LHC
 Weakly interacting
probes become
accessible (g, Z0, W±).
QM2004
√s
RHIC
SPS
Yves Schutz
4
3 experiments
JURA
ALPES
QM2004
Yves Schutz
5
HI experiments
Which particle multiplicity to expect at LHC ?
5
15.0
dNch/dh|h<1
Nch/(0.5Npart)

10.0
5.0
1.0
103
5
dNch/dh ~ 2500
1500
10
102
2
103
102
103
104
√s (GeV)
hep-ph0104010
 ALICE optimized for dNch/dY = 4000, checked up to 8000
(reality factor 2).
 CMS & ATLAS (checked up to 7000) will provide good
performances over the expected range.
QM2004
Yves Schutz
6
Solenoid magnet 0.5 T
Cosmic rays trigger
ALICE:
the dedicated HI experiment
Forward
detectors:
• PMD
• FMD, T0, V0, ZDC
Specialized detectors:
• HMPID
• PHOS
Central tracking system:
MUON Spectrometer:
• ITS
• absorbers
•TPC
• tracking stations
• TRD
• trigger chambers
• TOF
QM2004
Yves Schutz
7
• dipole
US EMCaL
(under discussion)
RICH
Pb/Sci EMCal
Dh x Df = 1.4 x 2p/3
TPC
TRD
ITS
TOF
QM2004
Yves Schutz
PHOS
8
ALICE:
the dedicated HI experiment
 Measure flavor content and phase-space
distribution event-by-event:
 Most (2p * 1.8 units h) 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;
 Jet identification;
QM2004
Yves Schutz
9
ALICE PID performances
ALICE PPR CERN/LHCC 2003-049
QM2004
Yves Schutz
10
ALICE tracking efficiency
ALICE PPR CERN/LHCC 2003-049
e
100%
TPC
only
1.2
0.8
Dp/p < 1%
0.4
0
QM2004
1
3
Yves Schutz
5
pt (GeV/c)
11
ALICE track resolution at high pt
Dp/p (%)
ALICE PPR CERN/LHCC 2003-049
50
30
9%
10
10
QM2004
50 pt (GeV/c)
Yves Schutz
100
12
ALICE construction status
QM2004
Yves Schutz
13
ALICE TPC
QM2004
Yves Schutz
14
ALICE Space Frame
QM2004
Yves Schutz
15
ALICE Dipole coil
QM2004
Yves Schutz
16
ALICE pixel
40K channels
200+150 mm
QM2004
Yves Schutz
17
CMS
• Central tracker
• High resolution
EM calorimeter
• Hadronic
calorimeter
• Very forward calorimeters
• ZDC
• CASTOR
• TOTEM
Superconducting solenoid magnet 4T
• Muon
spectrometer
QM2004
Yves Schutz
18
ATLAS
m detectors
EM calorimeter
Solenoid 2T
QM2004
Inner detector
H calorimeter
Yves Schutz
19
CMS & ATLAS
 Experiments designed for high pt physics in
pp collisions:
 Precise tracking systems in a large solenoid
magnetic field;
 Hermetic calorimeters (EM+Hadronic)
systems with fine grain segmentation;
 Large acceptance muon spectrometers;
 Accurate measurement of high energy
leptons, photons and hadronic jets.
 Provide adequate performances for selected
high pt (> 1 GeV/c) probes for HI physics.
QM2004
Yves Schutz
20
3 Experiments
T=LQCD
0
1
Qs
2
10
100
pt (GeV/c)
Hard processes
Modified by the medium
Bulk properties
ALICE
PID
CMS&ATLAS
QM2004
Yves Schutz
21
QGP probes: hard processes
modified by the medium
Q » LQCD, T, Qs  Dt, Dr ~ 1/Q
 Jet quenching:
 Energy degradation of leading hadrons, pt
dependence;
 Modification of genuine jet observables;
 Mass dependence of energy loss (light and heavy
quarks).
 Dissolution of c’onium & b’onium bound
states.
QM2004
Yves Schutz
22
Leading hadron
quenching
1
 Nuclear modification factor
pattern very different at
LHC:
0.5
 Final state interactions
(radiative & collisional
energy loss) dominate
RAA
over nuclear effects
(shadowing+Cronin).
 Measurement of
0.1
suppression pattern of
leading partons remains
experimentally the most
A+A √sNN = 200, 5500 GeV
straightforward observable 0.05
0
20 40 60 80 100
for jet-tomography analysis.
pt (GeV)
Vitev&Gyulassy QM02
QM2004
Yves Schutz
23
Jets reconstruction
 Jets are produced copiously.
20
2
100/event
100
1/event
200
pt (GeV)
100K/year
 Jets are distinguishable from the HI
underlying event.
QM2004
Yves Schutz
24
Performance by ATLAS
%
80
Efficiency
Fake jets
40
0
Cone algorithm R=0.4
Et > 30 GeV
DE/E (%)
20
50
150
250
10
Et
350
pp
0
50
QM2004
Energy resolution
PbPb
150
Yves Schutz
250
350
Et
25
Performance by CMS
Cone algorithm R=0.5
Et > 30 GeV
%
80
DE/E (%)
20
40
0
Energy resolution
10
0
50
150
250
Et
350
0
QM2004
0
Yves Schutz
100
200
Et
300
26
Jet quenching
 Excellent jet reconstruction… but
challenging to measure medium
modification of its shape…
Medium induced
redistribution of jet
energy occurs inside
cone.
medium
0.6
r(R)
R
vacuum
1
0.8
0.4
0.2
0
1
0.8
Et = 50 GeV
0.6
 Et=100 GeV (reduced average jet energy
fraction inside R):



Radiated energy ~20%
R=0.3 DE/E=3%
EtUE ~ 100 GeV
QM2004
0.4
0.2
0
Et = 100 GeV
0
0.2
0.4
0.6
0.8
1
R=√(Dh2+Df2)
C.A. Salgado, U.A. Wiedemann hep-ph/0310079
Yves Schutz
27
Exclusive jets:





Redistribution of jet energy
Jet shape: distance R to leading particle;
pT of particles for R < Rmax;
Multiplicity of particles for R < Rmax ;
Heating: kT = p  sin((particle, jet axis)) ;
Forward backward correlation: Df(particle, jet
axis);
 Fragmentation function: F(z)=1/NjdNch/dz
z=pt/pjet.
Requires high quality tracking down to low pt .
QM2004
Yves Schutz
28
p
Fragmentation functions
1/NjetsdNc/dz
z=pt/pjet
jet
103
reconstructed
10
input
1
vacuum
medium
10-1
0
0.5
z
z
pjet
1
10-2
10-4
kt
QM2004
Yves Schutz
0
0.5
z
29
1
Exclusive jets: Tagging
 Direct measurement of jet energy: g, g*, Z0
Channel
Statistics
(evts/month)
pt
(GeV)
106 6103
50 100
g*(μ+ μ-)- jet
104
50
Z0 (μ+ μ-)-jet
500 600
40
g-jet
QM2004
Yves Schutz
50
30
Exclusive jets: Tagging
 Direct measure of jet energy: g, g*, Z0
Low (< 10%)
background as
compared to
g/p0
QM2004
Yves Schutz
31
Heavy flavor quenching
observables
 Inclusive:
 Suppression of dilepton invariant mass
spectrum (DDl+l-, BB l+l- , B D+ l+)l Suppression of lepton spectra
 Exclusive jet tagging:
 High- pT lepton (B→Dl) & displaced
vertex
 Hadronic decay (ex. D0 K-p+) &
displaced vertex
QM2004
Yves Schutz
32
D quenching
(D0 K-p+)
nucl-ex/0311004
 Reduced
dN AA / dpt
1
RAA 

N coll dN pp / dpt
 Ratio D/hadrons (or D/p0) enhanced and
sensitive to medium properties.
QM2004
Yves Schutz
33
c/b Quarkonia
 1 month statistics of PbPb √sNN=5.5 TeV;
Y
J/
104
104
2
QM2004
3
4
h| < 2.4
|
9
dN/dh=8000
J/
dN/dh=5000
Events/100 MeV
Events/25 MeV
105
10
11
Mm+m-
Yves Schutz
Y
103
102
0
(GeV)
5
h
2.5 <
10
<4
15
34
Looking forward
 For a timely completion of LHC and
experiments construction in April 2007;
 Accelerators and experiments are today in the
production phase.
 For an exciting decade of novel HI physics
in continuation of the SPS and
complementary to RHIC;
 Detailed physics program, complementary
between 1+2 experiments, takes shape (see
PPRs, Yellow reports…).
 The 2004 challenge: demonstrate worldwide distributed Monte-Carlo production
and data analysis.
QM2004
Yves Schutz
35
Backup
QM2004
Yves Schutz
36
The LHC facility
QM2004
Yves Schutz
37
The LHC facility:
<L>/L0 1
average
L
b* = 2 - 0.5 m
IO = 108 ions/bunch
0.8
70%
0.6 Tuning time
55%
0.4
50%
1
2
3
Experiments
0.2
0
0
5
10
ALICE PPR CERN/LHCC 2003-049
QM2004
Yves Schutz
15
20
Time (h)
38
Novel aspects:
Quantitatively new regime
SPS
RHIC
LHC
√sNN (GeV)
17
200
5500
X 28
dNch/dy
500
850
1500-8000
?
t0QGP (fm/c)
1
0.2
0.1
faster
T/Tc
1.1
1.9
3.0-4.2
hotter
e (GeV/fm3)
3
5
15-60
denser
tQGP (fm/c)
≤2
2-4
≥10
tf (fm/c)
~10
20-30
30-40
Vf(fm3)
few 103
few 104
few 105
QM2004
Yves Schutz
longer
bigger
39
Novel aspects:
Qualitatively new regime
 Thermodynamics of the QGP phase  Thermodynamics of
massless 3-flavor QCD.
 Parton dynamics (tQGP/t0>50-100) dominate the fireball
expansion and the collective features of the hadronic final
state.
as(T)=4p/(18log(5T/Tc))
mu= md = ms
mu = m d
mu = md ; ms  mu,d
HQ suppressed exp(-mc,b,t/T)
QM2004
Yves Schutz
40
RHIC + CBM
Scientific objectives
of HI physics
 Study the QCD phase transition and the
physics of the QGP state:
LHC
 How to apply and extend the SM to a complex
and dynamically evolving system of finite size;
 Understand how collective phenomena and
macroscopic properties emerge from the
microscopic laws of elementary particle physics;
 Answer these questions in the sector of strong
interaction by studying matter under conditions
of extreme temperature and density.
QM2004
Yves Schutz
41
Heavy-ion running scenario






Year 1
 pp: detector commissioning & physics data
 PbPb physics pilot run: global event-properties,
observables with large cross-section
Year 2 (in addition to pp @ 14 TeV, L< 5.1030 cm-2s-1 )
 PbPb @ L~ 1027 cm-2s-1: rare observables
Year 3
 p(d, a)Pb @ L~ 1029 cm-2s-1 : Nuclear modification of
structure function
Year 4 (as year 2) : Lint = 0.5-0.7 nb-1/year
Year 5
 ArAr @ L~ 1027 -1029 cm-2s-1 : energy density dependencies
Options for later
 pp @ 5.5 TeV, pA (A scan to map A dependence), AA (A
scan to map energy-density dependence), PbPb (energyexcitation function down towards RHIC), ….
QM2004
Yves Schutz
42
Combined PID
Probability
Probabilityto
tobe
bea
proton
aa kaon
pion
QM2004
Yves Schutz
43
Inclusive jets by ALICE
R=0.3
pt > 2 GeV
● Original spectrum
● Measured spectrum DE/E = 25%
● Original spectrum for measured
energy 90 < ET < 110 GeV
QM2004
Yves Schutz
44
Exclusive jets:
Tagged jets
PbPb + 40 GeV g-jet
4
3
RAA
Tagging
2
No Tagging
1
0
0
10
20
30
40
0
10
20
30
40
pt (GeV)
QM2004
Yves Schutz
45
Heavy quarks jets
A. Dainese QM04
 Initially produced Qs experience the full
collision history:
 Short time scale for production: t1/mQ
 Production suppressed at larger times: mQ»T
 Long time scale for decay tdecay»tQGP
 The large masses of c and b quarks make
them qualitatively different probes (
massless partons)
 Radiative energy loss suppressed as
compared to q, g: (1+02/2)-2; 0=mQ/EQ
QM2004
Yves Schutz
46
D0 K-p+ reconstruction in ALICE
QM2004
Yves Schutz
47
QM2004
Yves Schutz
48
QM2004
Yves Schutz
49
ALICE TPC
EE
E E
Central electrode
QM2004
Yves Schutz
50
QM2004
Yves Schutz
51
D0 K-p+ reconstruction in ALICE
A. Dainese QM04
 Invariant-mass analysis of fullyreconstructed topologies originating from
displaced secondary vertices
QM2004
Yves Schutz
52
DE/E
0.2
0.1
0
0
20
C.A. Salgado, U.A. Wiedemann
QM2004
40
Cone angle (°)
Yves Schutz
53