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Initial Operation & Requirements on the Machine

Initial Operation & Requirements on the Machine. R. Bailey AB LHC Operations. Global requirements on the machine. Highest energy proton collisions for ATLAS and CMS Nominal luminosity 10 34 cm -2 s -1 in points 1 and 5 Highest energy proton collisions for LHCb

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Initial Operation & Requirements on the Machine

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  1. Initial Operation&Requirements on the Machine R. Bailey AB LHC Operations R.Bailey, LHCMAC, June 2005

  2. Global requirements on the machine • Highest energy proton collisions for ATLAS and CMS • Nominal luminosity 1034 cm-2 s-1 in points 1 and 5 • Highest energy proton collisions for LHCb • Nominal luminosity ~ 5 1032 cm-2 s-1 in point 8 • Proton collisions @ various energies for ALICE • Nominal luminosity ~ 1030 cm-2 s-1 in point 2 • Ion collisions @ various energies for ALICE • Nominal luminosity ~ 1027 cm-2 s-1 in point 2 • ATLAS and CMS will also take data • Proton collisions @ various energies for TOTEM Proton luminosity running Dedicated Dedicated R,Bailey, LHCMAC, June 2005

  3. Lower energy runs - From Chamonix XIV - • TOTEM would like to have low energy runs during the first phase of the LHC operation: • √s= 1.8 TeV for direct comparison with TEVATRON • √s ~ 8 TeV to measure • ALICE would like to have a dedicated pp run at √s= 5.5 TeV (nucleon-nucleon √s for nominal Pb-Pb runs) for a direct comparison of the Pb-Pb and pp data. A lower energy Pb-Pb run may be requested too. However both requests are for a later stage of the LHC operation • Lower energy pp runs during early running are also discussed • Low energy runs are currently neither in the ATLAS nor in the CMS baseline physics program. However this request may come at a much later phase of the LHC operation R,Bailey, LHCMAC, June 2005

  4. Proton luminosity running - From Chamonix XIV - HSM -> 4 l (MHiggs = 140-155 GeV and 190-450 GeV) can be discovered with ~ 4 fb-1 Some supersymmetry can be discovered at more modest luminosities ~ 1 fb-1 Potential for b-physics right from startup ATLAS and CMS • Minimize event pileup early on • Go to 25ns as soon as possible • Will make use of any beam for detector commissioning LHCb • Tune IP8 to optimize luminosity (1m <  *>50m) • Go to 25ns as soon as possible (optimized for ~ 1 events/crossing) • Dipole polarity change ~ every fill ALICE • Will use proton beams (intrinsic interest and reference data) • Tune IP2 to optimize luminosity (0.5m <  *>50m) • Magnet polarities change ( + - 0 ) a few times per year (106 seconds @ <L> of 1033 cm-2 s-1 = 1 fb-1) R,Bailey, LHCMAC, June 2005

  5. High luminosity running • Eventual goal: luminosity of 1034 cm-2 s-1 (ATLAS & CMS) R,Bailey, LHCMAC, June 2005

  6. 2808 is a lot of bunches per beam • Filling scheme requires 12 SPS cycles per beam • Each with 2,3 or 4 batches of 72 bunches • Crossing angle needed • Emittance conservation with 1011 protons per bunch through • Injecting • Ramping • Squeezing to 0.55m • This is going to take us a little while !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! R,Bailey, LHCMAC, June 2005

  7. 362MJ is a lot of beam energy to handle R,Bailey, LHCMAC, June 2005

  8. So how to get there ? • Both machine and experiments will have to learn how to stand running at nominal intensities • An early aim is to find a balance between robust operation and satisfying the experiments • Maximize integrated luminosity • Minimize event pile-up (to event + 2) • Avoid quenches (and damage) • Higher * to avoid problems in the (later part of) the squeeze • Reduce total current to reduce stored beam energy • Lower ib • Fewer bunches • Reduce energy to get more margin ? • Against transient beam losses • Against magnet operating close to training limit • Hardware commissioning will tell us more R,Bailey, LHCMAC, June 2005

  9. Other considerations • Electron cloud ( LHC simulations and SPS experience ) • ib < 35% nominal for 25ns spacing • ib ~ nominal for > 50ns • With lower currents in mind, two machine systems will be staged • Only 8 of 20 beam dump dilution kickers initially installed • Total beam intensity < 50% nominal • Install the rest when needed • Collimators ( robustness, impedance and other issues ) • Phased approach • Run at the impedance limit during phase I • Lower currents • Higher * Under review! R,Bailey, LHCMAC, June 2005

  10. Proposal for early proton running Phase I collimators and partial beam dump • Pilot physics run with few bunches • No parasitic bunch crossings • Machine de-bugging no crossing angle • 43 bunches, unsqueezed, low intensity • Push performance (156 bunches, partial squeeze in 1 and 5, push intensity) • 75ns operation • Establish multi-bunch operation • Relaxed machine parameters (squeeze and crossing angle) • Push squeeze and crossing angle • 25ns operation with Phase I collimators + partial beam dump • Needs scrubbing for higher intensities ( ib > 3 - 4 1010 ) Phase II collimators and full beam dump 4. 25ns operation • Push towards nominal performance R,Bailey, LHCMAC, June 2005

  11. Commissioning for Stage 1 - From Chamonix XIV - - 450GeV machine - R,Bailey, LHCMAC, June 2005

  12. - From Chamonix XIV - Commissioning for Stage 1 - Ramp and Squeeze - R,Bailey, LHCMAC, June 2005

  13. - From Chamonix XIV - - Ramp and Squeeze - - 450GeV machine - R,Bailey, LHCMAC, June 2005

  14. - From Chamonix XIV - Along the way • Equipment commissioning with beam • Machine protection commissioning • Instrumentation commissioning • First turn i.e. immediately • Screens, BPMs, fast BCT, BLMs • Circulating beams at 450 GeV • BPMs, DC BCT & lifetime, BLMs • Transverse diagnostics • Emittance: wire scanners.. • Snapback and Ramp • Chromaticity, PLL • Orbit • BLMs to BIC etc. • Checks with beam • BPM Polarity, corrector polarity, BPM response • Beam measurements • beam parameter adjustment, energy, linear optics checks, aperture • etc. etc. R,Bailey, LHCMAC, June 2005

  15. Stage 1 – pilot run luminosities • No squeeze to start • 43 bunches per beam (some displaced in one beam for LHCb) • Around 1010 per bunch • Push one or all of • Partial optics squeeze in 1 and 5 (2m ???) • Increase bunch intensity • 156 bunches per beam (some displaced in one beam for LHCb) R,Bailey, LHCMAC, June 2005

  16. Stage 2 – 75ns luminosities • Partial squeeze and smaller crossing angle to start • Luminosity tuning, limited by event pileup • Establish routine operation in this mode • Move towards nominal squeeze (1m ???) and crossing angle • Increase bunch intensity ? • Tune IP2 and IP8 to meet experimental needs • Down in IP8 (1m ???) • Up in IP2 (50m ??? Then transverse beam displacement probably needed) R,Bailey, LHCMAC, June 2005

  17. Stage 3 & 4 – 25ns luminosities • Production physics running • Start with bunch intensities below electron cloud threshold • Scrubbing run (1-2 weeks) • Increase bunch intensities to beam dump & collimator limit • Install beam dump kickers • Install phase II collimators • Increase bunch intensities towards nominal • Tune IP2 and IP8 to meet experimental needs • Transverse beam displacement certainly needed in IP2 Long shutdown (6months) R,Bailey, LHCMAC, June 2005

  18. * adjustments - Squeeze • Squeeze • Going to be tricky to set up in any case (Optics changes and collimators) • Foresee to do it after ramp to physics energy • IP 1 and 5 to 2m or maybe 1m should become routine • IP 8 to values between 10m and 1m more tricky • IP 2 to values between 10m and 50m more tricky • Squeezing at other energies will be even more tricky • Stick with injection optics at lower energies ? R,Bailey, LHCMAC, June 2005

  19. Filling • Filling • All the beams below have been made, but … • Complicated scheme for all physics runs • 12 SPS cycles per LHC ring • Procedures defined (LHC is the master) • Need to demonstrate that we can do it • Reliability implications for injectors • Compounded by LHCb magnet polarity switch R,Bailey, LHCMAC, June 2005

  20. Ions Experiment side • ALICE, ATLAS and CMS will all take Pb-Pb data • Detectors and machine will be already commissioned with pp • ALICE requests • 4 week ion runs at the end of each year • first short run as early as possible Machine side • Start with early ion scheme (62 bunches instead of 592, 7 107 ions per bunch) • Will have to • Re-commission injection, first turn • Set up RF capture and instrumentation • Re-commission ramp and squeeze • Establish collisions • Could do (some of) this early on if injectors are ready (same optics as for p) • Ion runs could provide cool down of PS SPS LHC after proton operation • After early ion scheme run, increase number of bunches • Move to nominal when possible - From Chamonix XIV - Estimate 1-3 weeks for first setup Followed by physics run R,Bailey, LHCMAC, June 2005

  21. Ion filling and luminosities R,Bailey, LHCMAC, June 2005

  22. TOTEM A standard TOTEM year would be • σtot measurement high priority • Nominal emittance OK for σtot, 1 μm needed for elastic scattering • 3 * 1 day runs at * of 1540m with 43 or 156 bunches per beam • 2 * 1 day runs at * of 18m with 2808 bunches per beam (25ns) ATLAS requests a period of a few weeks after first years of running Machine side • Special machine conditions, similar to polarisation runs at LEP • Very demanding on beam and optics quality, and for collimation • Initial setup will take several days (maybe better dispersed) • Subsequent setups should take a shift or two • Longer runs may be more efficient if machine reproducibility is an issue - From Chamonix XIV - R,Bailey, LHCMAC, June 2005

  23. TOTEM luminosities • Total Cross Section and Elastic scattering • Diffraction and minimum bias • Characterized by • Several 1 day runs per year (starting early) • Some single beam runs • 43 and 156 bunches per beam (as during Stage 1) • IP5 * = 1540m • IP5 * = 18m R,Bailey, LHCMAC, June 2005

  24. Scheduling - From Chamonix XIV - Every year we will need a long shutdown (3-4 months) At the end of every shutdown • Close the machine personnel access system • Get all equipment ready for beam (machine checkout, ~ 4 weeks) • Get machine ready for operation (setup with beam, 2-3 weeks) During periods of operation • Need regular technical stops (3 days every month) • Interventions need careful but flexible planning • Get machine ready for operation (1 day) • Machine development (around 15% during first years) • Operations for physics • Access as required for unscheduled stops R,Bailey, LHCMAC, June 2005

  25. Breakdown of a normal year - From Chamonix XIV - 7 • 140 days for physics per year • Not forgetting ion and TOTEM operation • Leaves ~ 100 days for proton luminosity running • ? Efficiency for physics 40% ? • 40 days ~ 1000 h ~ 4 106 s of colliding beams / year R,Bailey, LHCMAC, June 2005

  26. So the first few years could look like … • Starting in 07, phase II collimators in 09/10 R,Bailey, LHCMAC, June 2005

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