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The First Results from ALICE

The First Results from ALICE. In-Kwon Yoo (Pusan National Univ.) for the ALICE Collaboration. Outline. A Large Ion Collider Experiment at LHC Experimental Scheme PID and Performances Some Results to remark Strange Particles Jets Pion HBT Discussions. ATLAS. CMS. ALICE. The ALICE.

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The First Results from ALICE

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  1. The First Results from ALICE • In-Kwon Yoo (Pusan National Univ.) • for the ALICE Collaboration

  2. Outline • A Large Ion Collider Experiment at LHC • Experimental Scheme • PID and Performances • Some Results to remark • Strange Particles • Jets • Pion HBT • Discussions

  3. ATLAS CMS ALICE The ALICE • Pb+Pb @ 5.5 TeV in Large Hadron Collider

  4. LHC Workshop 2009 PID in ALICE Solenoid magnet 0.5 T ALICE: the dedicated HI experiment Why HMPID? • Forward detectors: • PMD • FMD, T0, V0, ZDC Full azimuthal coverage : ITS, TPC, ToF ITS, TPC upto p ~ 600 MeV/c ToF upto ~ 1.2 – 1.4 GeV/c Single-arm detector : HMPID for 1 – 5 GeV/c • Specialized detectors: • HMPID • PHOS • Central tracking system: • ITS • TPC • TRD • TOF • MUON Spectrometer: • absorbers • tracking stations • trigger chambers • dipole

  5. ALICE 2010 • ITS, TPC, TOF, HMPID, MUON, V0, T0, FMD, PMD, ZDC completed • TRD 7/18 • EMCAL 4/10 • PHOS 3/5

  6. ALICE Status 2x 2x 2x 4 5 3 2x 6 2 7 1 2x 8 0 9 17 10 16 15 11 14 12 13 4 0 3 1 2 Installation 2010/11 • Install 6 EMCAL, 3 TRD • Continuous 2 shifts operation • Significant Physics Gain • J/Ψ at TRD • Jets at EMCAL

  7. Motivation in pp • Necessity of the Hadronic reference for the observables • For Quark-Gluon Plasma study in AA collisions • Many Signals ‘relative’ to the pp results • Understanding the particle production in the new energy domain • Soft & Semi-hard QCD • Collective effects at the partonic level ?(Multiplicity dependence of the results)

  8. Trigger / Data samples • MinBias : at least one ch. particle in 8 units of eta (All ALICE is read out) • MBSPD / MBOR / MBAND • Single Muon Trg. (MUON, SPD, V0, FMD, ZDC are read out) • Available Statistics • 2009 (0.9 and 2.36 TeV) : ~ 0.5 M min.bias • 2010 (0.9 and 7 TeV) : ~ 700M min.bias, ~ 50M Muon trig.

  9. Event Classes σtot= σelas+ σs.dif+ σd.dif+ σn.dif • 0.9 and 2.36 TeV • INEL and NSD • MBOR / MBAND • MC : Apply the fractions of SD/INEL, DD/INEL • Pythia and Phojet • 7 TeV • MBSPD with |𝝶|<1

  10. ALICE CMS Mul. Evolution with ECM Inelastic Nch ≥ 1 in |h|<1 • Power law dependence fits quite well • Evolution is higher than expected in MCs. NonSingleDiffractive all Inelastic KLN CGC fits ~ s0.1

  11. Particle Identification TPC dE/dx 7 TeV pps ≈5-6% Vertex detector pT(min)<100MeV TOF 150k channels! s ≈ 90 ps

  12. Strangeness at 0.9 / 7 TeV

  13. ϕ / K*0 at 0.9 / 7 TeV

  14. Further Performances at 7 TeV J/Y → e+e- |y| < 0.9 w → p0p+p-(PHOS + TPC) J/Y → m+m-, y = 2.5 - 4 w/r/f → m+m-

  15. Open Charm at 7 TeV • Hadronic Decay of Open Charms • Even distinct Signal for D*+ • Heavy Flavors from Single Leptons (ongoing) Impact Parameter Resolution vs pT 80 mm @ 1 GeV

  16. Results • Final Results • Nchmultiplicity & distributions • 900 GeV: EPJC: Vol. 65 (2010) 111 • 900 GeV, 2.36 TeV: EPJC: Vol. 68 (2010) 89 • 7 TeV: EPJC: Vol. 68 (2010) 345 • pbar/p ratio (900 GeV & 7 TeV) PRL: Vol. 105 (2010) 072002 • Momentum distributions(900 GeV) PLB: Vol. 693 (2010) 53 • Bose-Einstein correlations (900 GeV) PRD: Vol. 82 (2010) 052001 • Under Collaboration Review • Identified particles (p,K,p) • Strangeness (K0,L,X,W,f) • Ongoing analyses • 7 TeV event properties: spectra, HBT, identified particles, strangeness, high multiplicity • Heavy flavour: charm (D0,D+, D*), heavy quarks (c,b) -> m, e- • J/y -> mm, e+e- • pQCD: Event topology, 2-particle correlations, jet fragmentation, …

  17. K/p Ratio at 900 GeV • Prel. Results: • very large K/p ratio at high pT • not reproduced by event generators • - practically no energy dependence

  18. X + X → L p Decays: K0S, L, X, f at 900 GeV L → p p K0S → pp • Prel. Results: • MC well below Data • more so at high pT • more so for L & X • f ~ ok (at least some MC) f → K K 13/10/2010 29th RRB J. Schukraft * 2009 Data (~300 k events)

  19. |h| < 1 L/K0SRatio 900 GeV 13/10/2010 29th RRB J. Schukraft • very good agreement between STAR (200 GeV) and ALICE (900 GeV) • very different from CDF (630/1800) and UA1 (630) for pT > 1.5 GeV • - UA1(630) and CDF(630) don’t agree either … • to be further investigated (different triggers, acceptance, feed-down correction ?)

  20. Associated pTt Δf Trigger pQCD: High pT Particle Correlations ‘near’ side ‘away’ side UE Trigger Particle Trigger Particle: highest pT particle in event (pTt) Associate Particle: all the others (pTa)

  21. Jet in pp at 0.9 TeV • internal structure of the jet : JT dispersion identical for 0.9 & 7 TeV

  22. More on ‘Event Shapes’ CMS result: unexpected ‘ridge’ in high Mult. pp somewhat similar phenomenon seen at RHIC in HI collisions • Particle Correlations in 2D ALICE acceptance smaller: Dh < 2 Atlas/ALICE/CMS WG established to compare results

  23. Bose-Einstein correlation • Space-Time Freeze-out configuration in pp • pion-pion HBT • 1D HBT (Qinv) vs. multiplicity and kT

  24. Rinv vs. Mul. & kT • Rinv grows with dN/d𝝶 • NO kT dependency

  25. Discussions • ALICE pp program • Do we correctly understand the hadron productions in pp? • Multiplicity Evolution with ECM? • Strangeness Production? • Ridge in pp? • HBT in pp? • Any collective behavior in high-mul events? • Multiplicity dependency • Ongoing • Efficiency Corrections • Identified Hadron Spectra / HBT • Jet Correction w.r.t. UEs • Further heavy flavors • Standby for AA physics in Nov. 2010 : 10-100 Hz Event rate / 107 MB evts. expected • ALICE Upgrade in 2012-13

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