1. Ken Read Oak Ridge National Laboratory/ University of Tennessee on behalf of the ALICE Collaboration SESAPS 2008, Raleigh, NC October 30, 2008 Research supported by the Office of Nuclear Physics, US Department of Energy

2. Heavy Ion Nuclear Physics  Ultrarelativistic heavy ion nuclear physics  Investigate properties of nuclear matter at high temperature and density  Improve understanding of strong force concerning deconfinement and chiral symmetry breaking/restoration (transition from quark to hadronic matter)  Explore QCD in novel regimes. Study the phase diagram of QCD matter.  Probe conditions of quark/hadron phase transition (universe at 10 -6 s) and fully characterize the properties of the novel produced matter 2 spectators participants

3. Heavy Ion Nuclear Physics 3

4.  Particles are flowing like an ideal hydrodynamical fluid. Viscosity/entropy ratio is lowest observed, near predicted quantum mechanical lower bound.  Suppression of particles with a high transverse momentum in Au+Au (but not d+Au) collisions as predicted to occur if QGP is formed (“jet suppression”). Opacity very high, effectively stops quarks and gluons.  Significant correlated emission of partons (“flow”) with shock-wave dynamics. Rapid thermalization of created medium, fluid expansion, even heavy quarks are swept up by flow. RHIC Discoveries 4

5.  More protons than pions at high transverse momentum. Almost as many anti-protons as protons, which is another indication that conditions are favorable for the production of a Quark-Gluon Plasma.  Energy density in the center of the collision is about 30 times that of a normal nucleus. Conditions may be favorable for Quark-Gluon Plasma production.  The source of produced particles is large and short-lived.  Modification of charm production measured via semileptonic decays.  Suggests that a new state of matter has been created at RHIC.  Anti de Sitter space / Conformal Field Theory (AdS/CFT) correspondence between QCD (quark gluon plasma) and string theory. The RHIC “fireball” can be “mapped” to a “gravity dual” (mathematical black hole) via this correspondence. RHIC Discoveries 5

6. Large Heavy ion Collider 6

7. LHC Specifications  LHC  p+p collisions at maximum energy of 14 TeV  Pb+Pb at 5.5 TeV per nucleon pair  Energy density 3 to 10 times higher than RHIC  ALICE is the dedicated heavy ion nuclear physics detector at the LHC. Sophisticated charged-particle tracking and particle identification capabilities.  ALICE-USA is primarily focused on the EMCal which provides a fast trigger on high-energy jets. SESAPS institutes (ORNL, Univ. Tennessee, …) are involved. 7

8. LHC Specifications 8 Collision System  s NN (TeV) Luminosity (cm -2 s -1 ) Run Time (s/yr)  geom (b) p+p14.010 34 10 7 0.07 Pb+Pb5.510 27 10 6 7.7 p+Pb8.810 29 10 6 1.9 Ar+Ar6.310 29 10 6 2.7 Integrated luminosity for Pb+Pb: 0.5 nb -1 /yr

9. Denser and Hotter 9 Central Collisions SPSRHICLHC s 1/2 (GeV)172005500  (GeV/fm 3 ) 3515 – 60 initial T (MeV)200300600 t QGP (fm/c)< 11.5 – 4.04 –10

10. Centrality 10 spectators participants b Lorentz-contracted ions in center of mass frame

11. Centrality 11 Centrality corresponds to impact parameter For a given b, Glauber model predicts N part and N coll. Hard processes tend to scale as ~ N coll Can classify events based on centrality class 15 fm b 0 fm 0 N coll 1200 0 N part 394

12. Centrality 12

13.  Initial state spatial anisotropy of reaction zone leads to final state momentum anisotropy  Results in asymmetric particle emission  Second component of Fourier decomposition, v 2, indicates degree of azimuthal anisotropy Flow 13 x z y Masashi Kaneta

14.  High transverse momentum particles probe the medium Probes 14 medium

15.     Variables 15

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17. 17 Simulated Event

18. 18 The “L3” Magnet

19. 19 The “L3” Magnet

20. 20 ALICE: Dedicated Heavy Ion LHC Experiment 31 Countries, 109 Institutes and more than 1000 members

21. ALICE  Detect most (2  * 1.8 units  ) of the hadrons (dE/dx + ToF), leptons (dE/dx, TOF, transition radiation) and photons (high resolution EM calorimetry, conversions)  Track and identify from very low ( 100GeV/c)  Identify short lived particles (hyperons, D/B meson) through secondary vertex detection  Excellent particle ID up to ~ 50 to 60 GeV/c 21

22. Time Projection Chamber  Specifications  designed for dN/dη=8000  |η|<0.9, radius 0.9-2.5m  0.5 T Solenoidal Field  570k chan., 80Mb/event  3% radiation length  Outer diameter 5 m, Length 5 m  Largest ever 22

23. TRD, TOF, HMPID  Transition Radiation Detector  p T >1 GeV electron id, p T >3 GeV trigger  540 modules, 4.8cm radiator with 1.2M chan.  MWPC readout  Time Of Flight  Multi-gap Resistive Plate Chambers (MRPC)  50 ps resolution at ~5m  |η|<0.85, Δφ=2π  High Momentum PID  Proximity focused, Ring Imaging CHerenkov RICH  |η|<0.6, Δφ=π/3  PID 1<p<6 GeV 23

24. PHOS  PHOton Spectrometer  PbO4W crystal calorimeter  ,  0,  for 1<p<100 GeV  |  |<0.12,  = 100º  L0 trigger at 900 ns  σ(E)/E = 3%, σ(x,y)=4mm 24

25. EMCal  Specifications  Lead-scintillator sampling calorimeter  13 k towers  Each tower ΔηXΔφ = 0.014 X 0.014  Shashlik geometry  Avalanche phototodiodes  Δη=1.4, Δφ=107º  σ(E)=0.15/  E + 0.02  L0 trigger at 900 ns for e, , and jets 25

26. EMCal  Specifications  High p T triggering possible on ,  0, and electrons. EMCal will significantly improve the statistics and energy resolution of jets.  EMCal has good high p T electron ID, including above p T ~ 10 GeV/c (beyond TRD reach) 26 Fiber bundles with attached photodiodes and preamps for 4 towers of an EMCal module

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28. ALICE EMCal Physics  Study Initial hard parton scattering  High energy jets, photons and heavy flavors → requires EMCal and triggering  Exploit large kinematic range of jets at LHC  Measure jet structure & medium-induced jet modification  Investigate energy loss  Low energy particles correlated with trigger or quenched jet → requires ALICE acceptance, robust tracking, & PID to low/high p T  Investigate energy propagation in medium to determine medium properties 28

29. ALICE EMCal Physics  Heavy flavor studies in ALICE will serve as sensitive probes of parton energy loss and the level of collectivity of the medium formed in heavy ion collisions.  The ALICE EMCal will provide improved high-p T identification and triggering of non-photonic electrons.  The displaced vertex method used in conjunction with the EMCal can provide efficient and pure identification of semi-electronic decays of B mesons. 29

30. Muon Spectrometer  Single muon acceptance  p>4 GeV/c  - 4.0 < η < - 2.5 30

31. Forward Detectors  FMD (Forward Multiplicity Detector)  3 planes Si-pad, -3.4<η<-1.7, -1.7<η<5.0  T0  2-arrays 12 quartz Cherenkov counters, 30ps res.  V0  2 arrays, 32 scintillator tiles, centrality trigger, 0.6ns res.  ZDC (Zero Degree Calorimeter)  2-neutron, 2-proton calorimeters, 116m from IP  also 2 EM calorimeters at -7 m  PMD (Photon Multiplicity Detector)  2.3< η <3.5 31

32. Readiness  All detectors fully installed except TRD, PHOS, EmCal, HLT to be completed  TRD(25%, completion 2010)  PHOS (60%, completion 2010)  EMCAL (0%, completion 2011) 32

33. Initial Program  Fully commissioned detector & trigger  alignment, calibration available from pp  First 10 5 events: global event properties  multiplicity, rapidity density  elliptic flow  First 10 6 events: source characteristics  particle spectra, resonances  differential flow analysis  Interferometry  First 10 7 events: high-p t, heavy flavors  jet quenching, heavy-flavor energy loss  charmonium production  Yield bulk properties of created medium  energy density, temperature, pressure  heat capacity/entropy, viscosity, sound velocity, opacity  susceptibilities, order of phase transition 33

34. Program  Initial low luminosity run  p+p  2 to 3 years (10 6 s/yr) Pb+Pb  1 year p+Pb  1 year Ar+Ar  Following requests depend on observations 34

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41. Conclusions  ALICE will start to collect p+p data next year  Later will measure Pb+Pb collisions at unprecedented energies  Will study jet suppression at still higher energies than measured at RHIC, as well as a broad program of related measurements concerning the produced matter.  Thanks to my colleagues on PHENIX and ALICE for contributed material.  See aliceinfo.cern.ch/Public 41