The heavy ion collider experiment @ LHC A L I C E Ginés MARTINEZ# for the ALICE Collaboration #Photon Group @ SUBATECH(IN2P3/CNRS – ENM - UN) Nantes, France Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001

Rencontres de Moriond March 17-24 2001 Outlook Why a Heavy Ion Experiment @ LHC? Goals Building ALICE Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001

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 Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001

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

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 Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001

Rencontres de Moriond March 17-24 2001 Why HI program @ LHC ? Central collisions SPS RHIC LHC s1/2(GeV) 17 200 5500 dNch/dy 500 700-1500 3-8 x103 e (GeV/fm3) 2.5 3.5-7.5 15-40 Vf(fm3) 103 7x103 2x104 tQGP (fm/c) <1 1.5-4.0 4-10 t0 (fm/c) ~1 ~0.5 <0.2 @ LHC : Hotter – bigger - longer J. Schukraft QM2001 Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001

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 Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001

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/0009237) Longer lifetime of the plasma Ideal plasma : e/ec ~ 5 : higher T Zero baryon density (already p/p ~ 0.6 @ RHIC) New probes : Jets, Open charm & beauty, bottonium Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001

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 Pb+Pb @ 5.5A TeV Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001

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 Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001

Jet Matter interaction 1-3 GeV/fm# Large production of jets @ 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 Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001

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 … Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001

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% @ 5 GeV/c Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001

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 Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001

High momentum particles High Momentum PID: Hard processes 1 GeV/c < p < 5 GeV/c Rich-imaging technique Small acceptance 7x HMPID Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001

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 Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001

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 Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001

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/9906325 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 Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001

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 Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001

ALICE = The result of QGP physics requirements at LHC + PMD FMD CASTOR ZDC Trigger DAQ Offline Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001

Rencontres de Moriond March 17-24 2001 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

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 Rendez-vous @ CERN March-April 2007 Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001

Rencontres de Moriond March 17-24 2001 A new research domain Quark Matter 2002 in Nantes Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17-24 2001