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

Peter G Jones, NP UK Community Meeting /12 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. Geneva French Alps ALICE, Point 2 (1.15 PeV or 0.18 mJ per ion)

Peter G Jones, NP UK Community Meeting /12 ALICE - Vital Statistics ITS Low p t tracking Vertexing ITS Low p t tracking Vertexing TPC Tracking, dEdx TPC Tracking, dEdx TRD Electron ID TRD Electron ID TOF PID TOF PID HMPID PID high p t HMPID PID high p t PHOS ,  0 PHOS ,  0 MUON  -pairs MUON  -pairs PMD  multiplicity PMD  multiplicity 16 metres high, 26 metres long, and ~10,000 tonnes

Peter G Jones, NP UK Community Meeting /12 ALICE – Observables ALICE is a general purpose detector Access to a wide range of observables in one experiment!

Peter G Jones, NP UK Community Meeting /12 ALICE - Main Features Excellent tracking and PID capabilities. High resolution tracking from 0.2 – 300 GeV/c. Powerful particle discrimination.

Peter G Jones, NP UK Community Meeting /12 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

Peter G Jones, NP UK Community Meeting /12 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 = cm -2 s -1 ) p-p collisions: 200 kHz interaction rate (L = 3  cm -2 s -1 ) David Evans / ALICE trigger

Peter G Jones, NP UK Community Meeting /12 ALICE - Key Physics Study QCD on its natural (energy) scale T > T C ≈  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. b cc b

Peter G Jones, NP UK Community Meeting /12 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) 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)

Peter G Jones, NP UK Community Meeting /12 ALICE – proton-proton physics ALICE has a competitive programme of pp physics Precision measurements of (total) cross-sections. Particle production as a function of p T. 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? p + p   0 + X

Peter G Jones, NP UK Community Meeting /12 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-p T and jet physics – energy loss (Barnby, Bombara, Evans, Lietava). Anomalous high multiplicity pp events – (Jones).

Peter G Jones, NP UK Community Meeting /12 Outlook and Summary Expect a short (1 week) Pb-run in From 2010, 1 month of Pb per year. First few years, Pb-Pb 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.