the h eavy i on c ollider e xperiment @ lhc a l i c e
DESCRIPTION
The h eavy i on c ollider e xperiment @ LHC A L I C E. Ginés MARTINEZ # for the ALICE Collaboration. # Photon Group @ S UBATECH(IN2P3/CNRS – ENM - UN) Nantes, France. Outlook. Why a Heavy Ion Experiment @ LHC? Goals Building ALICE. The study of the Quark Gluon Plasma. Krasch QM2001. - PowerPoint PPT PresentationTRANSCRIPT
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 1
The heavy ion collider experiment @ LHC
A L I C EGinés MARTINEZ#
for the ALICE Collaboration
#Photon Group @ SUBATECH(IN2P3/CNRS – ENM - UN) Nantes, France
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 2
Outlook
1. Why a Heavy Ion Experiment @ LHC?
2. Goals3. Building ALICE
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 3
The study of the Quark Gluon Plasma
• QCD-thermodynamics• Properties of the QGP and of
the phase transition:– Chiral transition– Deconfinement
Lattice QCD calculationsnf=2 Tc = 173±8±SysErr MeVnf=3 Tc = 153±8±SysErr MeVc= 700 ± 300 MeV
Krasch QM2001
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 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
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 5
collision dynamicsp+p and p+A
baseline !Sensitivity to late stages
in HI collisions!
The QGP phase
Final state probes
Penetratingprobes
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 6
Why HI program @ LHC ?
Central collisions SPS RHIC LHC
s1/2(GeV) 17 200 5500
dNch/dy 500 700-1500 3-8 x103
(GeV/fm3) 2.5 3.5-7.5 15-40
Vf(fm3) 103 7x103 2x104
QGP (fm/c) <1 1.5-4.0 4-10
0 (fm/c) ~1 ~0.5 <0.2
J. Schukraft QM2001@ LHC : Hotter – bigger - longer
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 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 (T >> QCD ) 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
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 8
• 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 c ~ 5 : higher T
– Zero baryon density (already p/p ~ 0.6 @ RHIC) – New probes : Jets, Open charm & beauty, bottonium
Advantages of Pb+Pb collisions @ LHC
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 9
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 ’s• 1700 K’s• 700 ’s• 570 p, n, p, n ‘s• ….
-1<<1
Pb+Pb @ 5.5A TeV
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 10
Penetrating probes
• Real and virtual photons
• Quarkonia: J/ & Y • Open Charm &
Beauty• Light vector mesons• Jets
• Initial stage
• Thermal radiation: Tini
• Colour screening of heavy quarks
• Jet-matter interaction• Chiral transition
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 11
Jet Matter interaction
B A
1-3 GeV/fm#
#Interference with vacuum and LPM,
Jet enhancementEjet dependence of E
pT> 10 – 20 GeV
1. High pT particle distributions2. Identification of jets …3. Tagging with photons:
• High pT particles• Jets
Looking for Jet matter interaction:
Urs. Wiedemann QM2001 et NPB588(00)203
Large production of jets @ LHC energies1 jet/GeV/s in the ALICE acceptance
at ET =50 GeV
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 12
Building ALICE
• Event Characterisation
• dNch/dy
• pT distribution• Particle ratios• Strange baryons• Fluctuations
• Light vector mesons• Quarkonium• Open charm & beauty• Photon & Dilepton• Jet quenching• …
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 13
dNch/d =1~ 8000
• Time Projection Chamber: Main tracking detector of ALICE central barrel• Inner radius: Track separationRin = 0.8 m• Outer radius: dE/dx & p resolution# Rout= 2.5 m • Large acceptance <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 …
#Magnetic field of the L3 magnet 0.4T 5% @ 5 GeV/c
1. PID below ~600 MeV/c 2. Low p tracks
Tracking efficiency ~90%2 tracks eff. 80% p>15 MeV/c
TPC
5 m
Ne+CO2(10%)
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 14
The ALICE PID
pT distributions•Particles ratios: Tfreeze-out
•Fluctuations•Strangeness production•Light vector mesons•Open charm •Jet physics
• 0.5 < p < 5 GeV/c
• e, , K, p
Time of FlightHigh Momentum Particle IdentificationTransition Radiation Detector
ToF prototypeALICE solution
• Large acceptance• MRPC• = 150 ps• ,K,p• 0.5<p<2.5 GeV/c
ToF
10cm
Multigap Resistive
Plate Chamber
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 15
High momentum particles
HMPID
High Momentum PID:• Hard processes
1 GeV/c < p < 5 GeV/cRich-imaging techniqueSmall acceptance
7x
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 16
Electron Identificator of ALICE
• Electron detector• 10-3 pion rejection• Large acceptance• Transition Radiation Detector
6x
• J/ in Zero baryon density• Open charm normalization• J/ source from Open Beauty• D annihilation?• production• Light vector resonances:
e channel
~ 103
EX ~ 3-30 KeV
Pb+Pb central collisionsTRD
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 17
Primary and secondary Vertex Position
• Secondary vertex from hyperon decays• Open charm & beauty physics• Tracking of low pT particles• Improving momentum resolution• Strangelets
• Large acceptance• 15000 tracks • ~100m in r
6 Silicon layers:1. 2 Silicon Pixel layers2. 2 Silicon Drift layers3. 2 Silicon Strip layers
ITS
K-
pITS
D =>Kevt
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 18
Photon detection• Thermal radiation• High pt physics• Tagged jets
• 1200 pT>40 GeV/c
• EM calorimeter• PbWO4: spectrometer: 0• Small acceptance 0.07 • 1< pT < 5 GeV/c• 5< pT <100 GeV/c
5x
PHOS ModulePHOS
Th
erm
al/D
ecay
1
0.1
10
1
2 3 pT(GeV/c)4
5%
hep-ph/9906325
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 19
Di muon channel
DiMuon
Quarkonium physics:J/ and Y families~ 100 MeV2.4 < < 4.0
ecoin.:•Intermediate rapidity•DD, BB production
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 20
ALICE = The result of QGP physics requirements at LHC
+PMDFMDCASTORZDCTriggerDAQOffline
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 21
Running conditions
• Pb+Pb @ 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 ions @ higher luminosity.
• Beginning 2007
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 22
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 @ CERN March-April 2007
Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001 23
A new research domain
Quark Matter2002
inNantes