The heavy ion collider experiment LHC ALICE Gins

The heavy ion collider experiment @ LHC ALICE Ginés MARTINEZ# for the ALICE Collaboration #Photon Group @ SUBATECH(IN 2 P 3/CNRS – ENM - UN) Nantes, France Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17 -24 2001 1

Outlook 1. Why a Heavy Ion Experiment @ LHC? 2. Goals 3. Building ALICE Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17 -24 2001 2

The study of the Quark Gluon Plasma Krasch QM 2001 Lattice QCD calculations nf=2 Tc = 173± 8±Sys. Err Me. V nf=3 Tc = 153± 8±Sys. Err Me. V ec= 700 ± 300 Me. V • QCD-thermodynamics • Properties of the QGP and of the phase transition: – Chiral transition – Deconfinement Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17 -24 2001 3

Towards QCD thermodynamics The TOOLS: Heavy Ion Collisions: SPS => RHIC => LHC The relation with QCD at finite temperature – The pp & p. A baseline – Equilibration – Probes of QGP formation? – QGP Initial conditions? Ginés MARTINEZ, SUBATECH Collision dynamics Rencontres de Moriond March 17 -24 2001 4

collision dynamics 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 5

Why HI program @ Central collisions SPS LHC ? RHIC LHC s 1/2(Ge. V) 17 200 5500 d. Nch/dy 500 700 -1500 3 -8 x 103 e (Ge. V/fm 3) 2. 5 3. 5 -7. 5 15 -40 Vf(fm 3) 103 7 x 103 2 x 104 t. QGP (fm/c) <1 1. 5 -4. 0 4 -10 t 0 (fm/c) ~1 ~0. 5 <0. 2 @ LHC : Hotter – bigger - longer Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17 -24 2001 J. Schukraft QM 2001 6

The gluon-gluon physics… • Gluon distribution in nuclei grows for small values of x = 2 p. T /s 1/2 and high gluon densities are reached. • For high densities (r. T >> L 2 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 PRD 10(74)1649, PRC 49(94)2233, PRD 49(94)3352, PRD 53(96)458, PRC 56(97)2219 Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17 -24 2001 7

Advantages of Pb+Pb collisions @ LHC • Better connection with QCD theory (via the asymptotically free field theory) A E – – – Initial gluon multiplicity (R. Venugopalan QM 01, PRL 86(01)1717) Initial equilibration conditions (D. Son QM 01, 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 8

Final state probes • • • Forward energy d. N/dy hadron p. T distribution Particle ratios Strange particles -1<h<1 Pb+Pb @ 5. 5 A Te. V Ginés MARTINEZ, SUBATECH • • • 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 • …. Rencontres de Moriond March 17 -24 2001 9

Penetrating probes • Real and virtual photons • Quarkonia: J/Y & Y • Open Charm & Beauty • Light vector mesons • Jets Ginés MARTINEZ, SUBATECH • Initial stage • Thermal radiation: Tini • Colour screening of heavy quarks • Jet-matter interaction • Chiral transition Rencontres de Moriond March 17 -24 2001 10

Jet Matter interaction 1 -3 Ge. V/fm# Dt 0 B A Large production of jets @ LHC energies 1 jet/Ge. V/s in the ALICE acceptance at ET =50 Ge. V Looking for Jet matter interaction: 1. High p. T particle distributions 2. Identification of jets … 3. Tagging with photons: • High p. T particles • Jets g #Interference with vacuum and LPM, Jet enhancement Ejet dependence of DE p. T> 10 – 20 Ge. V Ginés MARTINEZ, SUBATECH Urs. Wiedemann QM 2001 et NPB 588(00)203 Rencontres de Moriond March 17 -24 2001 11

Building • • • Event Characterisation d. Nch/dy p. T distribution Particle ratios Strange baryons Fluctuations Ginés MARTINEZ, SUBATECH • • • ALICE Light vector mesons Quarkonium Open charm & beauty Photon & Dilepton Jet quenching … Rencontres de Moriond March 17 -24 2001 12

d. Nch/dh • Time Projection Chamber: Main tracking detector of ALICE central barrel • Inner radius: Track separation Rin = 0. 8 m • Outer radius: d. E/dx & p resolution# Rout= 2. 5 m • Large acceptance Dh <0. 9 • 200 Hz rate capability • MWPC read-out 32 m 2, 40% Oc • 5 105 pads x 500 time bins • 60 Mbyte/evt => DC, Ro. I, L 3 … #Magnetic field of the L 3 magnet 0. 4 T 5% @ 5 Ge. V/c Ginés MARTINEZ, SUBATECH Dh=1~ 8000 Tracking efficiency ~90% 2 tracks eff. 80% Dp>15 Me. V/c 5 m TPC Ne+CO 2(10%) 1. PID below ~600 Me. V/c 2. Low Dp tracks Rencontres de Moriond March 17 -24 2001 13

ALICE PID lu so AL IC E • 0. 5 < p < 5 Ge. V/c • e, p, K, p ti on The p. T distributions • Particles ratios: Tfreeze-out • Fluctuations • Strangeness production • Light vector mesons • Open charm • Jet physics Ginés MARTINEZ, SUBATECH Time of Flight High Momentum Particle Identification Transition Radiation Detector To. F prototype To. F Multigap Resistive Plate Chamber • Large acceptance • MRPC • s= 150 ps • p, K, p • 0. 5<p<2. 5 Ge. V/c Rencontres de Moriond March 17 -24 2001 10 cm 14

High momentum particles High Momentum PID: • Hard processes 1 Ge. V/c < p < 5 Ge. V/c Rich-imaging technique Small acceptance 7 x HMPID Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17 -24 2001 15

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 e channel TRD • Electron detector • 10 -3 pion rejection • Large acceptance • Transition Radiation Detector Pb+Pb central collisions 6 x g ~ 103 EX ~ 3 -30 Ke. V Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17 -24 2001 16

Primary and secondary Vertex Position • Secondary vertex from hyperon decays • Open charm & beauty physics • Tracking of low p. T particles • Improving momentum resolution • Strangelets W- ITS p L K- p- I T S • Large acceptance • 15000 tracks • s~100 mm in rf 6 Silicon layers: 1. 2 Silicon Pixel layers 2. 2 Silicon Drift layers 3. 2 Silicon Strip layers Ginés MARTINEZ, SUBATECH D =>Kp 107 evt Rencontres de Moriond March 17 -24 2001 17

Photon detection Thermal/Decay 10 • Thermal radiation 5 x • High pt physics • Tagged jets • 1200 g p. T>40 Ge. V/c 1 PHOS 5% 0. 1 PHOS Module hep-ph/9906325 1 2 3 4 p. T(Ge. V/c) • EM calorimeter • Pb. WO 4: spectrometer: p 0, h • Small acceptance 0. 07 Dh. Df/2 p • 1< p. T < 5 Ge. V/c • 5< p. T <100 Ge. V/c Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17 -24 2001 18

Di muon channel Quarkonium physics: J/Y and Y families s~ 100 Me. V 2. 4 < h < 4. 0 Di. Muon em coin. : • Intermediate rapidity • DD, BB production Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17 -24 2001 19

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 20

Running conditions • • Pb+Pb @ 5. 5 A Te. V 106 s per year 8000 Hz (L=1027 cm-2 s-1) Data rate full ALICE 50 Hz (TPC challenge) pp & p. A running Lighter ions @ higher luminosity. Beginning 2007 Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17 -24 2001 21

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 22

A new research domain Quark Matter 2002 in Nantes Ginés MARTINEZ, SUBATECH Rencontres de Moriond March 17 -24 2001 23