YSchutz_PPTWin
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YSchutz_PPTWin Presentation Transcript

  • 1. Heavy-Ion Physics @ LHC
    • Program
    • Detectors
    • Observables
    • ~1100 participants:
    • 26 experimental contributions QM04
      • 6 oral : P. Glaessel, V. Manzari, A. Vestbo, H. Takai, B. Wyslouch, S. Blyth.
      • 20 posters : Spectra 23, HBT 1, High p T 17, 20, 21, Flavor 18, 19, 23, Instr. 1, 2, 7, 8, 10, 12, 14, 15, 16, 17, 22, 30.
    ATLAS 25 CMS 60 ALICE 1000
  • 2. The LHC facility
    • Running conditions:
    • + other collision systems: pA, lighter ions (Sn, Kr, Ar, O) & energies (pp @ 5.5 TeV) .
    April 2007 End 2007 Early 2008 *L max (ALICE) = 10 31 ** L int (ALICE) ~ 0.7 nb -1 /year Collision system PbPb pp <L>/L 0 (%) 10 7 Run time (s/year)  geom (b) L 0 (cm -2 s -1 ) √ s NN (TeV) 0.07 10 34 * 14.0 70-50 10 6 * * 7.7 10 27 5.5
  • 3. Novel aspects :
    • Probe initial partonic state in a novel Bjorken-x range ( 10 -3 -10 -5 ):
      • nuclear shadowing,
      • high-density saturated gluon distribution.
    • Larger saturation scale ( Q S =0.2A 1/6 √s  = 2.7 GeV ) : particle production dominated by the staturation region.
    Qualitatively new regime ALICE PPR CERN/LHCC 2003-049 J/ ψ 10 -6 10 -4 10 -2 10 0 x 10 8 10 6 10 4 10 2 10 0 M 2 (GeV 2 ) 10 GeV
  • 4. Novel aspects :
    • Hard processes contribute significantly to the total AA cross-section ( σ hard / σ tot = 98% ):
      • Bulk properties dominated by hard processes;
      • Very hard probes are abundantly produced.
    • Weakly interacting probes become accessible (  , Z 0 , W ± ).
    Qualitatively new regime LHC RHIC SPS (h + +h - )/2  0 17 GeV 200 GeV 5500 GeV = √ s LO p+p y=0
  • 5. 3 experiments JURA ALPES
  • 6.
    • Which particle multiplicity to expect at LHC ?
    • ALICE optimized for dN ch /dY = 4000 , checked up to 8000 (reality factor 2).
    • CMS & ATLAS (checked up to 7000 ) will provide good performances over the expected range.
    HI experiments dN ch /d  ~ 1500 dN ch /d  ~ 2500 hep-ph0104010 5 √ s (GeV) 10 10 2 10 3 10 2 10 3 10 4 1.0 5.0 10.0 15.0 N ch /(0.5N part ) dN ch /d  |  <1 2 5 10 3
  • 7. ALICE: the dedicated HI experiment
    • Central tracking system:
      • ITS
      • TPC
      • TRD
      • TOF
    • MUON Spectrometer:
      • absorbers
      • tracking stations
      • trigger chambers
      • dipole
    • Specialized detectors:
      • HMPID
      • PHOS
    • Forward detectors:
      • PMD
      • FMD, T0, V0, ZDC
    Cosmic rays trigger Solenoid magnet 0.5 T
  • 8. US EMCaL (under discussion) Pb/Sci EMCal  x  = 1.4 x 2  /3 TPC TRD TOF PHOS RICH ITS
  • 9. ALICE: the dedicated HI experiment
    • Measure flavor content and phase-space distribution event-by-event:
      • Most (2  * 1.8 units  ) 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 p t (~100 GeV/c; hard processes) ;
      • Identify short lived particles (hyperons, D/B meson) through secondary vertex detection;
      • Jet identification;
  • 10. ALICE PID performances ALICE PPR CERN/LHCC 2003-049
  • 11. ALICE tracking efficiency  p/p < 1% 100% p t (GeV/c) 1 3 5 0 0.4 0.8 1.2  ALICE PPR CERN/LHCC 2003-049 TPC only
  • 12. ALICE track resolution at high p t 10 100 p t (GeV/c) 50  p/p (%) 10 30 50  ALICE PPR CERN/LHCC 2003-049
  • 13. ALICE construction status
  • 14. ALICE TPC
  • 15. ALICE Space Frame
  • 16. ALICE Dipole coil
  • 17. ALICE pixel 40K channels 200+150  m
  • 18. CMS
    • Central tracker
    • High resolution EM calorimeter
    • Hadronic calorimeter
    Superconducting solenoid magnet 4T
    • Muon spectrometer
    • Very forward calorimeters
      • ZDC
      • CASTOR
      • TOTEM
  • 19. ATLAS Inner detector Solenoid 2T EM calorimeter H calorimeter  detectors
  • 20. CMS & ATLAS
    • Experiments designed for high p t 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 p t (> 1 GeV/c) probes for HI physics.
  • 21. 3 Experiments Bulk properties Hard processes Modified by the medium ALICE CMS&ATLAS PID T=  QCD Q s 0 1 2 10 100 p t (GeV/c)
  • 22. QGP probes: hard processes modified by the medium
    • Q »  QCD , T, Q s   ,  r ~ 1/Q
    • Jet quenching:
      • Energy degradation of leading hadrons, p t dependence;
      • Modification of genuine jet observables;
      • Mass dependence of energy loss (light and heavy quarks).
    • Dissolution of c’onium & b’onium bound states.
  • 23. Leading hadron quenching
    • Nuclear modification factor pattern very different at LHC:
      • Final state interactions (radiative & collisional energy loss) dominate over nuclear effects (shadowing+Cronin) .
    • Measurement of suppression pattern of leading partons remains experimentally the most straightforward observable for jet-tomography analysis.
    0 20 40 60 80 100 p t (GeV) 0.05 0.1 0.5 1 R AA A+A √s NN = 200, 5500 GeV Vitev&Gyulassy QM02
  • 24. Jets reconstruction
    • Jets are produced copiously.
    • Jets are distinguishable from the HI underlying event.
    p t (GeV) 2 20 100 200 100/event 1/event 100K/year 100 GeV jet + HI event
  • 25. Performance by ATLAS Cone algorithm R=0.4 E t > 30 GeV 50 150 250 350 0 40 80 % Efficiency Fake jets E t 50 150 250 350 E t 0 20 10 Energy resolution PbPb pp  E/E (%)
  • 26. Performance by CMS Cone algorithm R=0.5 E t > 30 GeV Energy resolution E t 50 150 250 350 0 40 80 % E t 0 20 10  E/E (%) 200 300 0 100 0
  • 27. Jet quenching
    • Excellent jet reconstruction… but challenging to measure medium modification of its shape…
    • E t =100 GeV (reduced average jet energy fraction inside R) :
      • Radiated energy ~20%
      • R=0.3  E/E=3%
      • E t UE ~ 100 GeV
    Medium induced redistribution of jet energy occurs inside cone. C.A. Salgado, U.A. Wiedemann hep-ph/0310079 R vacuum medium E t = 50 GeV E t = 100 GeV 0.2 0 0 0.4 0.6 0.8 1 0.2 R=√(  2 +  2 ) 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1  (R)
  • 28. Exclusive jets: Redistribution of jet energy
      • Jet shape: distance R to leading particle;
      • p T of particles for R < R max ;
      • Multiplicity of particles for R < R max ;
      • Heating : k T = p  sin(  (particle, jet axis)) ;
      • Forward backward correlation  (particle, jet axis);
      • Fragmentation function: F(z)=1/N j  dN ch /dz z=p t / p jet .
    Requires high quality tracking down to low p t .
  • 29. Fragmentation functions z=p t / p jet p jet 0 0.5 1 z 10 -4 10 -2 1 vacuum medium 0 0.5 1 z 1/N jets dN c /dz 10 -1 10 10 3 reconstructed input p jet z k t
  • 30. Exclusive jets: Tagging
    • Direct measurement of jet energy:  ,  *, Z 0
    40 500 Z 0 (  μ + μ - )-jet 50 10 4  *(  μ + μ - )- jet 50 10 6  -jet p t (GeV) Statistics (evts/month) Channel 50 600 100 6  10 3
  • 31. Exclusive jets: Tagging
    • Direct measure of jet energy:  ,  *,
    Z 0 Low (< 10%) background as compared to  /  0
  • 32. 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- p T lepton ( B->Dl  ) & displaced vertex
      • Hadronic decay (ex. D 0  K -  + ) & displaced vertex
  • 33. D quenching ( D 0  K -  + )
    • Reduced
    • Ratio D/hadrons (or D/  0 ) enhanced and sensitive to medium properties.
    nucl-ex/0311004
  • 34. c/b Quarkonia
    • 1 month statistics of PbPb √s NN =5.5 TeV;
    |  | < 2.4 2.5 <  < 4 Events/100 MeV 10 3 J/  Y 5 10 15 10 2 dN/d  =8000 M  +  - (GeV) Events/25 MeV 10 4 J/  Y 2 3 4 9 10 11 0 10 5 10 4 dN/d  =5000
  • 35. 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 world-wide distributed Monte-Carlo production and data analysis.
  • 36. Backup
  • 37. The LHC facility
  • 38. The LHC facility: average L Time (h) 1 2 3 Experiments  * = 2 - 0.5 m I O = 10 8 ions/bunch 70% 55% 50% Tuning time 0.2 0.4 0.6 0.8 1 < L >/ L 0 0 5 10 15 20 0 ALICE PPR CERN/LHCC 2003-049
  • 39. Novel aspects : Quantitatively new regime few 10 4 20-30 2-4 5 1.9 0.2 850 200 RHIC few 10 3 V f (fm 3 ) ~10  f (fm/c) ≤ 2  QGP (fm/c) 3  (GeV/fm 3 ) 1.1 T/T c 1  0 QGP (fm/c) 500 dN ch /dy 17 √ s NN (GeV) LHC SPS few 10 5 bigger 5500 X 28 1500-8000 ? 0.1 faster 3.0-4.2 hotter 15-60 denser 30-40 ≥ 10 longer
  • 40. Novel aspects :
    • Thermodynamics of the QGP phase  Thermodynamics of massless 3-flavor QCD.
    • Parton dynamics (  QGP /  0 >50-100 ) dominate the fireball expansion and the collective features of the hadronic final state.
    Qualitatively new regime m u = m d = m s m u = m d m u = m d ; m s  m u,d HQ suppressed exp(-m c,b,t /T)  s (T)=4  /(18log(5T/Tc))
  • 41. Scientific objectives of HI physics
    • Study the QCD phase transition and the physics of the QGP state:
      • 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.
    RHIC + CBM LHC
  • 42. 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< 5.10 30 cm -2 s -1 )
      • PbPb @ L~ 10 27 cm -2 s -1 : rare observables
    • Year 3
      • p(d,  )Pb @ L~ 10 29 cm -2 s -1 : Nuclear modification of structure function
    • Year 4 (as year 2) : L int = 0.5-0.7 nb -1 /year
    • Year 5
      • ArAr @ L~ 10 27 -10 29 cm -2 s -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 (energy-excitation function down towards RHIC), ….
  • 43. Combined PID Probability to be a pion Probability to be a kaon Probability to be a proton
  • 44. Inclusive jets by ALICE
    • Original spectrum
    • Measured spectrum  E/E = 25%
    • Original spectrum for measured energy 90 < E T < 110 GeV
    R=0.3 p t > 2 GeV
  • 45. Exclusive jets: Tagged jets p t (GeV) R AA PbPb + 40 GeV  -jet 1 0 10 20 30 40 0 2 3 4 Tagging 0 10 20 30 40 No Tagging
  • 46. Heavy quarks jets A. Dainese QM04
    • Initially produced Qs experience the full collision history:
      • Short time scale for production:  1/m Q
      • Production suppressed at larger times: m Q »T
      • Long time scale for decay  decay »  QGP
    • 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+  0 2 /  2 ) -2 ;  0 =m Q /E Q
  • 47. D 0  K -  + reconstruction in ALICE
  • 48.  
  • 49.  
  • 50. ALICE TPC E E 510 cm E E 88  s Central electrode
  • 51.  
  • 52. D 0  K -  + reconstruction in ALICE A. Dainese QM04
    • Invariant-mass analysis of fully-reconstructed topologies originating from displaced secondary vertices
  • 53. Cone angle (°) 0 20 40 0 0.1 0.2 C.A. Salgado, U.A. Wiedemann  E/E