J.M. Jowett, S. Maury, PANIC05 HI Satellite meeting, 23/11/ LHC as a Heavy-Ion Collider An update John M. Jowett, Stephan Maury I-LHC Project CERN Presented by Bolek Wyslouch

J.M. Jowett, S. Maury, PANIC05 HI Satellite meeting, 23/11/ The LHC Injector Chain - Schematic LEIR 72 MeV/n Pb 6 GeV/n Pb 177 GeV/n Pb 2.76 TeV/n Pb-Pb LEIR 72 MeV/n Not to scale

J.M. Jowett, S. Maury, PANIC05 HI Satellite meeting, 23/11/ e  A e x 200  s Linac3 output after stripping 2 Same physical emittance as protons, LHC Pb Injector Chain: Key Parameters for luminosity cm -2 s -1 Stripping foil

J.M. Jowett, S. Maury, PANIC05 HI Satellite meeting, 23/11/ LEIR (Low-Energy Ion Ring) n n Prepares beams for LHC using electron cooling n n circumference 25m (1/8 PS) n n Multiturn injection into horizontal+vertical+lon gitudinal phase planes n n Fast Electron Cooling : Electron current from 0.5 to 0.6 A with variable density n n Dynamic vacuum (NEG, Au-coated collimators, scrubbing) RF E-Cooling Injection Ejection D0D0D0D0 D=0 Ejection kicker Quadrupole triplet Quadrupole doublet dipole RF vacuum sector 4

J.M. Jowett, S. Maury, PANIC05 HI Satellite meeting, 23/11/ First Circulating Beam in LEIR n Schottky spectrum of the circulating beam of O 4+ ions in LEIR on October 11, n Three harmonics of the revolution frequencies around the 100th are shown. n Beam made full turn of the ring immediately on first injection. n Circulated for up to 200 ms. n Vacuum leak problem since then …

J.M. Jowett, S. Maury, PANIC05 HI Satellite meeting, 23/11/ LHC Collisions with Lead Ions n 208 Pb Pb 82+ collisions n CM energy 1.15 PeV with nominal dipole field. Beam energy 2.76 A TeV n ALICE detector specialises in heavy ion physics n CMS and ATLAS are also interested in heavy ion physics

J.M. Jowett, S. Maury, PANIC05 HI Satellite meeting, 23/11/ Operational parameter space with lead ions I b m 1. ´ ´ ´ ´ ´ ´ L cm 2 s - 1 Visibility threshold on FBCT Nominal Visible on BCTDC Early Visibility threshold on arc BPM BFPP Quench limit, Collimation limit? Nominal single bunch current Visible on BCTDC Thresholds for visibility on BPMs and BCTs.

J.M. Jowett, S. Maury, PANIC05 HI Satellite meeting, 23/11/ Luminosity evolution: Nominal scheme An “ideal” fill, starting from design parameters giving nominal luminosity. Particles per bunch Transverse emittance Luminosity Increasing number of experiments reduces beam and luminosity lifetime. BPM visibility threshold

J.M. Jowett, S. Maury, PANIC05 HI Satellite meeting, 23/11/ Example: average luminosity Average luminosity with 3h turn-around time, in ideal fills starting from nominal initial luminosity. Maximum of curve gives optimum fill length. Average luminosity with 3h turn-around time, in ideal fills starting from nominal initial luminosity. Maximum of curve gives optimum fill length. Average luminosity depends strongly on time taken to dump, recycle, refill, ramp and re-tune machine for collisions. Beams will probably be dumped to maximise average L before BPM visibility threshold is reached.

J.M. Jowett, S. Maury, PANIC05 HI Satellite meeting, 23/11/ I-LHC Planning n Baseline: Lead-Lead collisions –“Early Pb Scheme” – much easier to achieve – for 2008 (and 2009?) n Allows study of performance limitations. –“Nominal Pb Scheme” by 2009 (or 2010?) n Pb-Pb is perceived as posing the most difficult accelerator physics problems n Future “upgrades” not in Baseline: –p-Pb collisions under study n Effects of revolution frequency difference at injection expected to be much weaker than at RHIC –lighter ion-ion collisions (e.g. Ca, Ar, O, …) appear possible without major upgrades, to be studied.

J.M. Jowett, S. Maury, PANIC05 HI Satellite meeting, 23/11/ Summary n Operation of LHC with lead ions limited by new effects, qualitatively different from protons Several effects important around level of design luminosity (uncertainties in their estimation but some recent grounds for optimism) n Restricted to a narrow operational range of parameters below the nominal luminosity n “Early scheme” will allow relatively safe commissioning, access good initial physics n Study of p-Pb mode has begun, looks promising n LEIR commissioning has started with some success and some setbacks …