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Heavy Ions at the LHC

Heavy Ions at the LHC. Peter G. Jones University of Birmingham, UK. NP UK Community Meeting, Cosener’s House, 10-11 September 2008. French Alps. Geneva. LHC Status. First beam circulated yesterday! Short proton-proton run at 900 GeV, then ramp to 10 TeV.

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Heavy Ions at the LHC

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  1. Heavy Ions at the LHC Peter G. Jones University of Birmingham, UK NP UK Community Meeting, Cosener’s House, 10-11 September 2008

  2. French Alps Geneva LHC Status • First beam circulated yesterday! • Short proton-proton run at 900 GeV, then ramp to 10 TeV. • Full energy: 14 TeV (protons), 5.5 TeV per nucleon (Pb ions). • Normal running: ~7 months protons, ~1 month Pb ions per year. (1.15 PeV or 0.18 mJ per ion) ALICE, Point 2

  3. HMPID PID (RICH) @ high pt TRD Electron ID PMD g multiplicity TPC Tracking, dEdx ITS Low pt tracking Vertexing MUON m-pairs PHOS g,p0 ALICE - Vital Statistics 16 metres high, 26 metres long, and ~10,000 tonnes TOF PID

  4. ALICE – Observables • ALICE is a general purpose detector • Access to a wide range of observables in one experiment!

  5. ALICE - Main Features • Excellent tracking and PID capabilities. • High resolution tracking from 0.2 – 300 GeV/c. • Powerful particle discrimination.

  6. Birmingham – Profile in ALICE • History of involvement in CERN experiments since mid-1980s • NA36 (Jones, Nelson) • NA49 (Barnby, Jones, Nelson) • WA85 (Evans*, Kinson,Villalobos-Baillie) • WA94 (Evans, Kinson*, Villalobos-Baillie) • WA97/NA57 (Bombara, Evans, Kinson, Lietava, Villalobos-Baillie) • Birmingham’s role in ALICE • Responsible for ALICE trigger system. • Only major subsystem owned wholly by a single university group. • Seat on Management and Technical Boards. • Strong involvement in the science (Physics Performance Reports). • Now one of the largest groups in ALICE. • Currently preparing for first (early pp) physics. * = spokesperson

  7. ALICE – Trigger • Features • Up to 60 inputs (every 25 ns) • 24 L0 – 100 ns decision time • 24 L1 – 1 s decision time • 12 L2 • 50 trigger classes • Inputs, detectors, • past/future protection, • rare/not rare … • 6 detector clusters • 4 past/future protections • Rates • Pb-Pb collisions: 8 kHz interaction rate (L = 1027 cm-2s-1) • p-p collisions: 200 kHz interaction rate (L = 31030 cm-2s-1) David Evans / ALICE trigger

  8. l+ jets p l– g* p g c b K p p ALICE - Key Physics • Study QCD on its natural (energy) scale T > TC ≈ QCD. • Explore quark and gluon dynamics in a hot medium. • Hot topics: • Collective behaviour – flow. • Opacity to jets – energy loss (gluon bremsstrahlung). • Heavy flavour production. • Some new theoretical developments: • AdS/CFT correspondance – gravity dual. • Connection between string theory ... • … and strongly-coupled gauge theories. • Provides an alternative to (lattice) QCD. • Some (limited) success so far. c b

  9. New ideas in Hadronization David d'Enterria (CERN) David Evans (Birmingham) Nick Evans (Southampton) Nigel Glover (IPPP) Peter Jones (Birmingham) Frank Krauss (IPPP) Kasper Peeters (MPI) Marija Zamaklar (Durham)

  10. p + p 0 + X ALICE – proton-proton physics • ALICE has a competitive programme of pp physics • Precision measurements of (total) cross-sections. • Particle production as a function of pT. • Data on fragmentation functions. • Study of diffractive events. • Probes nucleon structure. • Advantages of ALICE • Low transverse momentum coverage. • Particle tracking. • Particle identification. • More speculative … • Multiplicity: pp (LHC) = CuCu (RHIC) • QGP in pp collisions?

  11. UK – ALICE Physics • First (proton-proton) physics • Multiplicity and transverse momentum distributions. • Lietava is leading one of the first physics working groups. • Initial tests of QCD; input to fragmentation functions. • Are parton distributions sufficiently well understood? • Correction for trigger biases • Important for all papers. • Longer term proton-proton physics – Pb-Pb physics • Resonances – sensitive to hadronic phase (Villalobos-Baillie). • Charmonium (J/) production – Debye screening (Lazzeroni). • High-pT and jet physics – energy loss (Barnby, Bombara, Evans, Lietava). • Anomalous high multiplicity pp events – (Jones).

  12. Outlook and Summary Expect a short (1 week) Pb-run in 2009. From 2010, 1 month of Pb per year. First few years, Pb-Pb collisions @ 5.5 TeV per nucleon. Option of changing beam species/energy in subsequent years. • e.g. p-Pb, symmetric light ions, lower energy(ies). LHC will achieve first collisions very soon. ALICE has a full physics programme. UK is helping to shape that programme. First physics  proton-proton collisions  Pb-Pb collisions.

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