Quarkonia Measurements with ALICE Frederick Kramer IKF, Goethe-Universität Frankfurt WWND, Ocho Rios, Jan 8, 2010 Helmholtz Research School H-QM Quark Matter Studies IKF Institut für Kernphysik Frankfurt
Outline Motivation Physics Goals LHC - New Perspectives The Experiment ALICE Transition Radiation Detector Performance Studies Direct Quarkonia Secondary J/ψ Frederick Kramer Quarkonia Measurements with ALICE 2 / 19
Physics Goals Quarkonia: Bound states of heavy quark pairs, created in early stage of collision Primary physics goals: Study elementary production mechanism (p+p) Probe properties of the QGP (A+A) Frederick Kramer Quarkonia Measurements with ALICE 3 / 19
Elementary Reactions Quarkonia production: Colour Singlet Model Colour Octet Model Colour Evaporation Model [Phys. Lett. B333 (1994) 548-554] Frederick Kramer Quarkonia Measurements with ALICE 4 / 19
Elementary Reactions Quarkonia production: Colour Singlet Model Colour Octet Model Colour Evaporation Model Contribution from feed-down: χ c J/ψ + γ B J/ψ + X or ψ + X [Phys. Lett. B333 (1994) 548-554] Measure d2 σ dydp t Production models PDFs to distinguish between: Frederick Kramer Quarkonia Measurements with ALICE 4 / 19
Heavy Ions Competing mechanisms: 1. Quarkonia production 2. Feed down from higher mass quarkonia 3. QGP induced effects: Melting (Debye screening) Recombination (uncorr. Q Q) 4. Cold nuclear matter effects: Nuclear absorption Shadowing Need to disentangle! Frederick Kramer Quarkonia Measurements with ALICE 5 / 19
Necessary Measurements Measure quarkonia in different systems: p+p: elementary processes, baseline for A+A p+a: cold medium effects, baseline for A+A A+A: interaction with hot medium Frederick Kramer Quarkonia Measurements with ALICE 6 / 19
LHC - New Perspectives snn N c c/ev. (GeV) cent. AA SPS 17.3 0.2 RHIC 200 10 LHC 5500 115 LHC will deliver excellent statistics for quarkonia measurements! Frederick Kramer Quarkonia Measurements with ALICE 7 / 19
ALICE 1000 members from 111 institutes from 31 countries ITS Solenoid EMCAL Muon Tracking TRD Muon Filter Muon Trigger TOF TPC PHOS Absorber Dipole ITS: Inner Tracking System, TPC: Time Projection Chamber, TRD: Transition Radiation Detector Frederick Kramer Quarkonia Measurements with ALICE 8 / 19
Transition Radiation Detector 7/18 supermodules installed and operational 6 layers of drift chamber + radiator Factor 100 in π rejection (p > 3 GeV) cathode pads pion electron anode wires amplification region cathode wires drift region primary clusters Drift Chamber entrance window x z Radiator pion TR photon electron Frederick Kramer Quarkonia Measurements with ALICE 9 / 19
Transition Radiation Detector First analysis of real data! (p+p, 900 GeV) Average Pulse Height <PH> (ADC ch.) 300 250 200 pp@lhc electrons pions 150 100 50 0 5 10 15 20 25 30 Time bin (100 ns) Frederick Kramer Quarkonia Measurements with ALICE 10 / 19
The TRD as Trigger Detector L1: trigger on high momentum single electron/electron pair HLT: full online data analysis ( trigger on e + e inv. mass), event selection and compression Online display of the vertex positions reconstructed by the ALICE HLT First collisions (p+p, 900 GeV) Nov/Dec 2009 [EPJC, Vol. 65 (2010) pp. 111-125] Frederick Kramer Quarkonia Measurements with ALICE 11 / 19
J/ψ µ + µ Event display from first collisions! Frederick Kramer Quarkonia Measurements with ALICE 12 / 19
Motivation The Experiment Performance Studies Summary J/ψ µ+ µ J/ψ Υ Υ Υ ψ 1 nominal LHC year (w/ trigger) J/ψ Υ S 4.7M 44.7k S/B 12.6 5.8 195 S/ S + B 2081 [ALICE PPR v2 CERN/LHCC 2005-030] p+p simulation 14 TeV η Frederick Kramer Quarkonia Measurements with ALICE 13 / 19
J/ψ µ + µ J/ψ Υ Υ Υ ψ 1 nominal LHC year (w/ trigger) J/ψ Υ S 130k 1300 S/B 0.2 1.7 S/ S + B 150 29 Resolution (MeV/c 2 ) 70 100 Pb+Pb simulation 5.5 TeV [ALICE PPR v2 CERN/LHCC 2005-030] η Frederick Kramer Quarkonia Measurements with ALICE 14 / 19
J/ψ e + e Entries/Events -6 10 ρ ω φ J/Ψ -7 10 Ψ(2S) -8 10 Υ 0 2 4 6 8 10 12 2 invariant mass [GeV/c ] 0.2 nominal LHC year (min bias) J/ψ S 360 S/B 9 S/ S + B 18 Resolution (MeV/c 2 ) 30 p+p simulation 14 TeV [arxiv:nucl-ex/0702045v1] η Frederick Kramer Quarkonia Measurements with ALICE 15 / 19
J/ψ e + e Entries/Events -4 10 J/Ψ Ψ(2S) all contributions BG from open charm BG from open beauty BG from misidentified π s -5 10-6 10 uncorr. BG (like sign) Υ(1S) Υ(2S) Υ(3S) -7 10-8 10 0 2 4 6 8 10 12 2 Invariant Mass [GeV/c ] 10% most central 1 nominal LHC year (min bias) J/ψ Υ S 120k 900 S/B 1.2 1.1 S/ S + B 245 21 Resolution (MeV/c 2 ) 30 90 Pb+Pb simulation 5.5 TeV [arxiv:nucl-ex/0702045v1] η Frederick Kramer Quarkonia Measurements with ALICE 16 / 19
Secondary J/ψ χ 36.0% c1,2 20.0% J/ψ + γ 5.94% 8.3% e + e - (conversion) e + e - Identify in M(e + e γ) spectrum 30% contribution to yield M = M(e + e γ) M(e + e ) p+p 14 TeV, 1 nominal LHC year 12, 000 χ c (perfect trigger) [EPJC 10.1140/epjc/s10052-009-0895-4] Frederick Kramer Quarkonia Measurements with ALICE 17 / 19
Secondary J/ψ B J/ψ + X 5.94% e + e - cτ 500µm likely to have a displaced vertex B fraction: Simultaneous fit of inv. mass + pseudo proper decay time (CDF approach) x = L xy M J/ψ p t L xy = L pt p t and L = rvtx sec r prim vtx 20-30% contribution to yield p+p 14 TeV, 1 nominal LHC year [J.Phys.G:Nucl.Part.Phys 36 (2009) 064053] [PRD 71 032001 (2005)] Frederick Kramer Quarkonia Measurements with ALICE 18 / 19
Summary LHC provides a very good environment for quarkonia measurements ALICE will measure quarkonia Dielectron (midrapidity) and dimuon channel (forward) Secondary J/ψ reconstruction Dedicated triggers Acceptance down to pt = 0 Clear signals are expected in triggered samples in 1st year s min. bias samples for J/ψ (Pb+Pb: also Υ) Very good mass resolution to separate between Q Q states LHC start end of 2009 very successful, so far 0.36 M p+p events s = 0.9 TeV with all detectors Frederick Kramer Quarkonia Measurements with ALICE 19 / 19