1 / 37

Physics in ALICE at the LHC

Physics in ALICE at the LHC. Alice. Dedicated “general purpose” Heavy Ion experiment at LHC. ALICE at the LHC. LHC. The ALICE Experiment. (charged particles). µ arm. ALICE Detectors & Acceptance. central barrel -0.9 < h < 0.9 Df = 2 p tracking, PID (TPC/ITS/ToF)

varian
Download Presentation

Physics in ALICE at the LHC

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Physics in ALICE at the LHC John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  2. Alice Dedicated “general purpose” Heavy Ion experiment at LHC ALICE at the LHC LHC John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  3. The ALICE Experiment John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  4. (charged particles) µ arm ALICE Detectors & Acceptance central barrel -0.9 < h < 0.9 • Df = 2p tracking, PID (TPC/ITS/ToF) • single arm RICH (HMPID) • single arm e.m. cal (PHOS) • jet calorimeter (EMCal) forward muon arm 2.4 < h < 4 • absorber, 3 T-m dipole magnet10 tracking + 4 trigger chambers multiplicity detectors -5.4 < h < 3 • including photon counting in PMD trigger & timing detectors • 6 Zero Degree Calorimeters • T0: ring of quartz window PMT's • V0: ring of scint. Paddles John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  5. The ALICE Experiment (Installation) John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  6. ALICE Detectors in 2009 at LHC • Complete – fully installed & commissioned • ITS, TPC, TOF, HMPID, MUONS, PMD, V0, T0, FMD, ZDC, ACORDE, TRIGGER, DAQ • Partially completed • TRD (20%) completed now • PHOS (20%) completed now • EMCAL (20%) just completed, installation in current shutdown • At start-up full hadron and muon capabilities • Partial electron and photon capabilities John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  7. separation power to 50 GeV The TPC Performance Tracking (cosmic rays) Energy loss (dE/dx) ~6.5% resolution in central Pb+Pb PID John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  8. First LHC Beam in ALICE • ALICE ready for LHC collisions. • First LHC proton beams circulated on September 10th , 2008. • 450 GeV/c proton + pixel interaction John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  9. Early p + p Physics in ALICE • “Day 1” physics with p + p: • global event properties (energies - 0.9/10/14 TeV?) • requires only several x 10K events Multiplicity distributions < dNch /dh |h = 0> < pT > vs Nch John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  10. ALICE Heavy Ion Physics Overview: Soft Probes – “same as RHIC and Beyond” • Expansion dynamics different from RHIC • Soft physics measurements similar to RHIC + extended PID • Day 1 physics + Hard Probes – Heavy Quarks • Displaced vertices (Do K- p+) from TPC/ITS • Electrons in Transition Radiation Detector (TRD) Hard Probes – Quarkonia • J/y, , ’ (excellent),’’(2-3 yrs),y’ ??? Hard Probes – Jet Quenching • Jets, g , pi-zeros, leading particles to large pT John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  11. Soft Physics in ALICE LHC Heavy Ions – • expectations based on QCD predictions, p + p extrapolations, & RHIC results • a lesson from RHIC “expect the unexpected”  versatility!!  ALICE!! Soft Physics (pT≤ 2 GeV/c) with heavy ions at LHC – • Is there a smooth extrapolation from SPS  RHIC LHC? dNch/dy = 2600 ALICE saturation model Eskolahep-ph/050649 Particle Multiplicities dNch/dy = 1200 ln(√s) extrapolation J. Phys. G 30 (2004) 1540 John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  12. Soft Physics in ALICE LHC Heavy Ions – • expectations based on QCD predictions, p + p extrapolations, & RHIC results • a lesson from RHIC “expect the unexpected”  versatility!!  ALICE!! Soft Physics (pT≤ 2 GeV/c) with heavy ions at LHC – • smooth extrapolation from SPS  RHIC LHC? • expansion will be different (HBT, v2, Tchem & Tkin, • strange/charm particles & resonances) N.Borghini & U.A.Weidemann, J.Phy.G 35 (2008) 023001 Hirano et al, nucl-th/0701075v2 John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  13. Equilibrium / Non-Equilibrium in ALICE B. Hippolyte et al. EPJ C49 (2007) Rafelskiet al. E. J. Phys. C45 (2006) 61 Non-equilibrium s (gs = 3 - 5) oversaturated Andronic et al. nucl-th/0511071 Equilibrium gs = 1 • at LHC expect : Tch = 161 ± 4 MeV • mB = 0.8+1.2-0.6 MeV Many additional questions: Strangeness enhancement? Correlation volume? Evolution in pp & PbPb? John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  14. Resonances (, , K*, …)  Hadrons Short-lived resonances: • Time difference between chemical and kinetic freeze-out • In medium modifications of mass, width, comparison of hadronic and leptonic channels → partial chiral symmetry restoration? • Reconst invariant mass spectrum, background subtract (like-sign method). • Mass resolutions ~ 1.5 - 3 MeV . pT statistical limits: 8 () to 15 GeV/c (,K*) f (1020)  K+K- r0(770)p+p- 106central Pb-Pb Mass resolution ~ 1.2 MeV K*(892)0 K p 15000 central Pb-Pb Invariant mass (GeV/c2) Invariant mass (GeV/c2) Mass resolution ~ 2-3 MeV Invariant mass (GeV/c2) John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  15. Resonances (, , w, J/y)  e+e- Short-lived resonances: • In medium modifications of mass, width, comparison of hadronic and leptonic channels → partial chiral symmetry restoration? 2 x 107 Pb+Pb events John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  16. Resonances (, , w, J/y)  e+e- Short-lived resonances: • In medium modifications of mass, width, comparison of hadronic and leptonic channels → partial chiral symmetry restoration? 2 x 107 Pb+Pb events 2 x 107 Pb+Pb events -w, f: significance = 12 - 15 J/y: significance = 40 - 50 John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  17. Hard Probe Rates in ALICE ALICE hard physics capabilities: - Electron/hadron disc. (TRD, EMCal) - m measurements (forward muon arm) - Goodg/p0discrimination (EMCal, PHOS) - Fast trigger on jets (EMCal) • Hard Probes statistics in ALICE: • 104/year in minbias Pb+Pb: • inclusive jets: ET ~ 200 GeV • dijets: ET ~ 170 GeV • p0: pT ~ 75 GeV • inclusive g: pT ~ 45 GeV • inclusive e: pT ~ 30 GeV Thanks – Peter Jacobs John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  18. Hard Probes in ALICE – Heavy Quarks Heavy Quarks (mass/color dep. of parton E-loss) • Displaced vertices (Do K- p+) from TPC/ITS • Electrons in Transition Radiation Detector (TRD) John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  19. Heavy Quark RAA at RHIC & LHC! Heavy quark electrons at RHIC D & B mesons at LHC LHC RHIC Wicks & Gyulassy, Last Call for LHC Predictions Uncertainties at RHIC (bands > ±0.1 ) - perturbative production of c and b jets - ratio of c to b jets is very uncertain. LHC: - Different slopes of spectra John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  20. Charm & Beauty E-Loss Ratios in ALICE Displaced vertices (Do K- p+) from tracking Electrons from Transition Radiation Detectors 1 nominal year: 107 central Pb-Pb events, 109 pp events errors: statistical (bars) and systematic (bands) Sensitive to color charge Sensitive to mass dep. E-loss calc.: Armesto, Dainese, Salgado, Wiedemann John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  21. Charm and Beauty E-Loss : RAA D+ Kpp D0 Kp B  e + X mC = 1.2 GeV mC = 0 E-loss calc: Armesto, Dainese, Salgado, Wiedemann B  e 1 year at nominal luminosity (107 central Pb-Pb events, 109 pp events)) mb = 4.8 GeV John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  22. Hard Probes in ALICE – Quarkonia Heavy Quarks (mass/color dep. of parton E-loss) • Displaced vertices (Do K- p+) from TPC/ITS • Electrons in Transition Radiation Detector (TRD) Quarkonia (Initial T, Debye screening, recombination,..) • J/y, , ’ (excellent),’’(2-3 yrs),y’ (very difficult) John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  23. T/TC 1/r [fm-1] (1S) J/(1S) b’(2P) c(1P) ’’(3S) ’(2S) Quarkonia Heavy Quarks (mass/color dep. of parton E-loss) • Displaced vertices (Do K- p+) from TPC/ITS • Electrons in Transition Radiation Detector (TRD) Quarkonia (Initial T, Debye screening, recombination,..) • J/y, , ’ (excellent),’’(2-3 yrs),y’ (very difficult) Karsch hep-lat/0502014v2 Measure melting order of cc: Y’, cc, J/y bb: U’’, U’, U John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008 John Harris (Yale U.) US LHC User’s Meeting, 24 October 2008

  24. Quarkonia Performance dNch/dy = 4000 in central Pb-Pb for 1 month

  25. Hard Probes in ALICE – Jet Quenching Heavy Quarks (mass/color dep. of parton E-loss) • Displaced vertices (Do K- p+) from TPC/ITS • Electrons in Transition Radiation Detector (TRD) Quarkonia (Initial T, Debye screening, recombination,..) • J/y, , ’ (excellent),’’(2-3 yrs),y’ (very difficult) Jet Quenching (in next talk by Rene Bellwied) (E-loss, parton density, fragmentation, medium response) • Jets, g , pi-zeros, leading particles to large pT • Modification of fragmentation • Medium response to E deposition - dissipation on near- and away-side John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  26. Summary & Questions to Address • ALICE – is a versatile, general purpose heavy ion detector at LHC • will contribute significantly to understanding of (soft & hard) HI physics • ALICE to address general (Soft Physics) Questions: • How does the system evolve and thermalize from its initial state? • What are the properties of the quark-gluon plasma at LHC energies? • Is QCD Phase Diagram featureless above Tc? • Coupling strength vs T….? • Are there new phenomena? • ALICE to address Physics Questions with Hard Probes: • What is the behavior of c-cbar and b-bar states in-medium? • (Ti, screening/suppression, enhancement?) • Can we understand parton energy loss at a fundamental level? • Medium modifications? • e.g. jet energies in ALICE up to ~ 225 GeV possible (stats) • B-jets up to 80 – 90 GeV (stats in one PbPb month) • Flavor dependence? (D, B, quark- and gluon-jets?) • Can we understand the hadronization (fragmentation) process? • Theory? • Range of validity of theories (hydro, non-pQCD, pQCD, strings…)? • Can there be new developments in theory, and understanding across fields? (lattice, hydro, string, pQCD E-loss,…)

  27. End John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  28. Backup John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  29. ALICE Goals for Data • First physics in ALICE will be pp - important reference data for heavy-ions • Unique pp physics in ALICE - examples • multiplicity distribution • baryon transport • measurement of charm cross section major input to pp QCD physics • First 105 PbPb events: global event properties • multiplicity, rapidity density • elliptic flow • First 106 PbPb events: source characteristics and spacetime evolution • particle spectra, resonances • differential flow analysis • interferometry • First 107 PbPb events: high-pt, heavy flavours • jet quenching, heavy-flavour energy loss • charmonium production • Eventual goals - bulk properties of medium • energy density, temperature, pressure • heat capacity/entropy, viscosity, sound velocity, opacity • susceptibilities, order of phase transition John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  30. Wicks et al, nucl-th/0512076 Fragmentation Function of b-quark Measure B-jet Fragmentation Fctn - harder fragmentation of b-quark (higher <z> ) - Ejet measured more precisely - Better measurement of FF B-jet Physics WHDG, arXiv:nucl-th/0512076 Quark vs gluon E-loss in medium B-jets - pure sample of quark jets John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  31. ALICE B-jet Physics WHDG, arXiv:nucl-th/0512076 John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  32. Rate s sbb (LHC ) ~ 100 sbb (RHIC) scc (LHC) ~ 10 scc (RHIC) Hard Probes with LHC Heavy Ions • Significant increase in hard cross sections • (pT or mass > 2 GeV/c) at LHC –  slarge pT /stotal~ 2% at SPS • 50% at RHIC • 98% at LHC • “real” jets, large pT processes • abundance of heavy flavors • probe early times, calculable John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  33. Centrality Determination in ALICE Event by event determination of centrality: Zero Degree Calorimeters (ZDC) + Z Electro-Magnetic calorimeters (ZEM) E(ZDC) , E(ZEM) Nspec Npart Impact parameter (b) John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  34. pp Track Efficiency Challenge in high-particle density environment For realistic particle densities dN/dy = 2000 – 4000 combined efficiency well above 90% and fake track probability below 5% all detectors Efficiency normalized to number of generated particles at primary vertex within the central acceptance |η|<0.9 protons – large absorption kaons – decays on flight John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  35. Momentum Resolution Robust, redundant tracking from < 100 MeV/c to > 100 GeV/c Little dependence on dN/dy to dN/dy ≈ 8000 Central PbPb pp at high momentum determined by - point measurement precision - and the alignment & calibration at low momentum dominated by - ionization-loss fluctuations - multiple scattering John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  36. Identified Particle Spectra Particle reconstruction and identification capabilities: unique to ALICE Global tracking (ITS-TPC-TRD) + dE/dx (low pT + relativ. rise), TOF, HMPID, PHOS, … Invariant mass, topological reconstruction Acceptance / efficiency / reconstruction rate (e) / contamination pT range (PID or stat. limits) for 107 central Pb-Pb and 109 min. bias pp For ~ 20 particle species for -1 < y < +1 and -4 < y < +2.5 p, K, p: 0.1- 0.15 to 50 GeV Weak or strong decaying particles: to 10-15 GeV Mid-rapidity p PID in the relativistic rise K p Pb-Pb Pb-Pb pT (GeV/c) John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

  37. Material Budget Cumulative mid-rapidity material budget for ALICE, ATLAS and CMS  Ideal Reconstruction and identification low pT : lowest material budget Hot Quarks 2008 - Estes Park B.Hippolyte John Harris (Yale U.) Winter Workshop, Big Sky MT, 1 – 8 Feb. 2009

More Related