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Recent Results from ALICE at the LHC
Kai Schweda Physikalisches Institut University of Heidelberg Seminar, TU München 22 Nov 2010
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Building Blocks of Matter
Quantum Chromodynamics (QCD) is the established theory of strongly interacting matter. Gluons hold quarks together to from hadrons: Gluons and quarks, or partons, typically exist in a color singlet state: confinement. meson baryon 22 Nov 2010 Seminar, TU München
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Quark Gluon Plasma Quark Gluon Plasma: deconfined and
Source: Michael Turner, National Geographic (1996) Quark Gluon Plasma: deconfined and thermalized state of quarks and gluons Study partonic EoS at highest collider energies 22 Nov 2010 Seminar, TU München
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QCD phase diagram 22 Nov 2010 Seminar, TU München
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High-energy nucleus-nucleus Collisions
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Outline Introduction LHC and ALICE Global event properties in pp @ LHC
Hard probes: heavy-quark production First results from 2.76 TeV Summary 22 Nov 2010 Seminar, TU München
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Large Hadron Collider LHC at CERN Alice LHC 7 TeV c - 10 km/h
Tevatron TeV c km/h RHIC GeV c km/h Geiger and Marsden MeV c * 5%
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Nominal LHC Running Conditions
Collision system √sNN(TeV) L0 (cm-2s-1) Run time (s/year) geom (b) p + p 14.0 1034 * 107 0.07 Pb + Pb 5.5 1027 106 ** 7.7 p + Pb 8.8 1029 106 1.9 Ar + Ar 6.3 2.7 *Lmax (ALICE) = 1030cm-2s-1 ** Lint (ALICE) ~ 0.5 nb-1/year 22 Nov 2010 Seminar, TU München
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Expectations for LHC Cross-sections of interesting probes
expected to increase relative to RHIC by factors ~ 10 ( ) to ~ 102 ( ) to > 105 (very high pT jets) LHC is the ultimate machine for quark matter studies with hard-probes 22 Nov 2010 Seminar, TU München
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The ALICE Collaboration
> 1000 members ~ 100 institutes 30 countries 150 million US $ 22 Nov 2010 Seminar, TU München
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Size: 16 x 26 meters Weight: 10,000 tons Detectors: 18 TRD ITS TPC 10
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3 x 2 Layers Silicon Technology
Strips SSD Inner Tracking System ~ 10 m2 Si detectors, 6 layers double sided Strips, Drift, Pixels Pixels SPD Drift SDD
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Inner Tracking System SSD SDD SPD Lout=97.6 cm Rout=43.6 cm
6 Layers, three technologies (keep occupancy ~constant ) Silicon Strip (double-sided) 4.9 m2 2.6M channels Silicon Drift m2 133k channels Silicon Pixels m2 9.8M channels 22 Nov 2010 Seminar, TU München
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Silicon Pixel Alignment
SPD Point resolution σΔx = √2 x σspatial Data: σspatial = 14 μm Simulation: σspatial = 11 μm ALICE: K. Aamodt et al., J. Inst. 5 (2010) P03003. 22 Nov 2010 Seminar, TU München 13
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Time Projection Chamber
Most challenging TPC ever built Radius: mm Drift length:2 x 2500 mm Drift time: 92 µs Gas mixture Ne-CO2-N2 Gas volume: 90 m3 readout pads Material: (η=0) 3% X0 5 m 22 Nov 2010 Seminar, TU München
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TPC im Juni ‘06 15
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TRD readout-electronics
PASA TRAP 2 custom made chips - pre-amplifier (PASA) - signal processor (TRAP): in total 275k CPUs, 65 MBytes of raw data processed within 6.5s Multi Chip Module (MCM) 22 Nov 2010 Seminar, TU München
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Assembly of 1st TRD Module - Heidelberg
Chip-Module mit Kühlelementen TRD Modul 6th layer completed transport to CERN Sep 2006 Installation of 2nd layer 22 Nov 2010 Seminar, TU München
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22 Nov 2010 Seminar, TU München
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23-November-2009: first p+p collision recorded in ALICE !
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22 Nov 2010 Seminar, TU München
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p+p Data on Tape* p+p @ 0.9 TeV, 8 M minimum bias ( 111 b-1)
TeV, 35k minimum bias (486 mb-1) 7 TeV, 820 M minimum bias (12 nb-1) M high multiplicity (15 nb-1) M muon triggers (130 nb-1) *p+p data taking finished 04-Nov-2010 22 Nov 2010 Seminar, TU München
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Charged Particle Density
ALICE 7 TeV: Eur.Phys.J.C68: ,2010; ALICE 0.9/2.36 TeV: Eur.Phys.J.C68:89-108,2010. Multiplicity increases faster than predicted by models Challenge to theory 22 Nov 2010 Seminar, TU München
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Momentum Distribution
Spectrum measured from very low to high momentum, small uncertainties in extrapolation Average momentum not well described by either models K. Aamodt at al., PLB 693 (2010) 53. 22 Nov 2010 Seminar, TU München
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Particle Identification
TPC dE/dx: separate p from K up to 1.1 GeV Time of flight: separate K from up to ~ 1.5 GeV 22 Nov 2010 Seminar, TU München
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(Anti)-Proton Production at LHC
At LHC energies: Ratio of anti-p/p 1 No need for exotic baryon transport mechanism Address hadro-chemistry in PbPb within 1 day ALICE, Phys. Rev. Lett. 105, (2010). 22 Nov 2010 Seminar, TU München
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Particle Spectra Large momentum coverage of identified particles
Address hadro-chemistry in PbPb within 1 day 22 Nov 2010 Seminar, TU München
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Photon Pair Conversions
Photon conversions +Z e+e- + Z allow for detailed study of material budget Material budget between collisions vertex and TPC now known to better than 7% Precise knowledge of material budget and alignment essential for open charm studies ! 22 Nov 2010 Seminar, TU München
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Heavy - flavor: a unique probe
mc,b » QCD : new scale mc,b ≈ const., mu,d,s ≠ const. initial conditions: test pQCD, R, F probe gluon distribution early partonic stage: diffusion (), drag () flow, jets, correlations probe thermalization hadronization: chiral symmetry restoration confinement statistical coalescence J/ enhancement / suppression Q2 time X. Zhu, M. Bleicher, S.L. Huang, K.S., H. Stöcker, N. Xu, and P. Zhuang, PLB 647 (2007) 366. 22 Nov 2010 Seminar, TU München
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Heavy quark Correlations
Charm and anti-charm quarks created in pairs and thus correlated Look for modificaions in Pb+Pb collisions PYTHIA: p + 14 TeV Heavy-quark production correlated due to QCD processes such as pair creation (backward), gluon splitting (forward), etc. Expetced for pp Modified in PbPb --> probe early thermalization X. Zhu, M. Bleicher, S.L. Huang, K.S., H. Stöcker, N. Xu, and P. Zhuang, PLB 647 (2007) 366. G. Tsildeakis, H. Appelshäuser, K.S., J. Stachel, arXiv: , subm. To NPA. 22 Nov 2010 Seminar, TU München
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Where does all the charm go ?
J/ c D*+ Ds D0 D± Total charm cross section: open-charm hadrons, e.g. D0, D*, c, … or c,b e() + X Quarkonia, e.g. J/ carries 1% of total charm 22 Nov 2010 Seminar, TU München
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Heavy-quark detection
Open-charm reco. in ALICE D0 K D+ K D* D0 Under study: Ds KK D0 K c pK c c K0S e.g., D0 K- + , c = 123 m displaced decay vertex is signature of heavy-quark decay 22 Nov 2010 Seminar, TU München
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D*+ identified up to 12 GeV/c
D*+ D0 + + Signal D*+ identified up to 12 GeV/c 22 Nov 2010 Seminar, TU München
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Open-charm spectra from ALICE
1/7 of total statistics, up to 12 GeV/c; extend to 20 GeV/c 22 Nov 2010 Seminar, TU München
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Open-charm ratios from ALICE
Ratios coincide with results at lower energies 22 Nov 2010 Seminar, TU München
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Quarkonia production J/ e+e- (central barrel, y 0)
J/ +- (forward directions, -4 < y -2.5) Charmonium production still challenge to models 22 Nov 2010 Seminar, TU München
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p+p Summary ALICE has identified most hadrons consisting of 1st and 2nd generation quarks (u,d,s,c), also charged leptons (e,) down to lowest momentum Essential input for models - soft vs hard processes Open and hidden charm production cross sections underway Key reference for Pb+Pb physics program Much more to come… 22 Nov 2010 Seminar, TU München
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First Pb+Pb collisions in ALICE !
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Charged-particle multiplicity
ALICE, submitted for publication, arXiv: [nucl-ex]. 22 Nov 2010 Seminar, TU München
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Anisotropy Parameter v2
coordinate-space-anisotropy momentum-space-anisotropy y py x px Initial/final conditions, EoS, degrees of freedom
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v2 in the low-pT Region P. Huovinen, private communications, 2004 v2 approx. linear in pT, mass ordering from light to heavier characteristic of hydrodynamic flow, sensitive to EOS ! 22 Nov 2010 Seminar, TU München
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Elliptic flow in ALICE 22 Nov 2010 Seminar, TU München
ALICE, submitted for publication, arXiv: [nucl-ex]. 22 Nov 2010 Seminar, TU München
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LHC: Tentative Schedule
23-Nov-2009: 1st pp collisions at 900 GeV 30-Nov-2009: protons accelerated to 1.18 TeV in both rings Dec-2009: 1st pp collisions at 2.36 TeV 2010/11*: long run with pp collisions at 7(8) TeV 08-Nov-2010: 1st Pb+Pb collisions at 2.76 TeV Nov 2011: one more month of Pb+Pb collisions 2012: Machine consolidation and training 2013: pp and Pb+Pb at full energy *technical stop during Dec/Jan 22 Nov 2010 Seminar, TU München
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ALICE - harvesting physics!
22 Nov 2010 Seminar, TU München
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Particle Intensity Interferometry
Source size dependence on transverse pair momentum not observed 22 Nov 2010 Seminar, TU München
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Non-ideal Hydro-dynamics
Spectra and flow reproduced by ideal hydrodynamics calcs. Shear viscosity to entropy density ratio close to AdS/CFT bound Hydro-limit exceeded at LHC ? M.Luzum and R. Romatschke, PRC (2008); P. Romatschke, arXiv: 22 Nov 2010 Seminar, TU München 45
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Hanbury-Brown Twiss Interferometry
Width in correlation function 1/R Measure source size R R. Hanbury Brown and R. Q. Twiss, Nature 178, 1046 (1956); G. Goldhaber et al., Phys.Rev.Lett.3,181(1959). 22 Nov 2010 Seminar, TU München
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More Open charm from ALICE
D0 K-+ D+ K -++ Study open charm production in as many channels as possible 22 Nov 2010 Seminar, TU München
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TPC commissioning transverse momentum resolution, B=0.5 T
particle identification via dE/dx resolution: measured 5.7% design % resolution at 10 GeV: measured 6.0% design % 22 Nov 2010 Seminar, TU München
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First Pb+Pb collisions in ALICE !
22 Nov 2010 Seminar, TU München
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