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The LHC: what to expect (in the first 2 years)

The LHC: what to expect (in the first 2 years). * Machine Milestones and Components * LHC Commissioning (2007,2008) - 450 GeV Engineering Run Staged Approach * Commissioning Challenges. A. Drees. ALICE-US Collaboration Meeting, Oct. 6 2006. 4.3 km. Machine Milestones.

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The LHC: what to expect (in the first 2 years)

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  1. The LHC: what to expect (in the first 2 years) • * Machine Milestones and Components • * LHC Commissioning (2007,2008) • - 450 GeV Engineering Run • Staged Approach • * Commissioning Challenges A. Drees ALICE-US Collaboration Meeting, Oct. 6 2006

  2. 4.3 km

  3. Machine Milestones • cryo-magnet cold tests are on schedule to finish in 2006 • magnet installation rate is now >/= 25/week • last magnet in the ring: Mar 07 • interconnect rate allows vacuum closure in Aug 07 • no collisions at higher energy possible in 2007 • engineering run at 450 GeV • machine checkout scheduled Nov. 1 2007 • engineering run scheduled to begin mid Nov. 2007

  4. Machine Components 8 octants 8 IRs 4 experiments almost 10000 dipoles • almost 100 collimators • betatron & momentum cleaning in 2 IRs • RHIC: only 5 per Ring two rings: ring 1 (blue) ring 2 (red)

  5. LHC Naming Conventions and Locations • 1232 main dipoles • 752 H,V-correctors • 2464 sextupole correctors • blue beam clockwise (ring1) • red beam counterclockwise (ring2)

  6. Why a 450 GeV Engineering Run? • chance to check-out the machine with beam and have a window to address problems • commission beam instrumentation (BI) • aperture, machine protection, controls … • collimators • could also do in MD • 1st part of ramp (to ~1.1 TeV) • limited magnet cycling needed to reset hysteresis • 1.2 TeV, 1900 A in main bends, 16% nom. • linear correctors to full current • higher order corrections (>b3) can be skipped • Full beam commissioning to 7 TeV will profit and go faster and more efficiently

  7. LHC 450 GeV 1st commissioning and setup for collisions

  8. Some Parameters and Assumptions for the 450 GeV Engineering Run • pilot bunch • single bunch, 3 1010 p/bunch • number of bunches: • max. of 156 (no crossing angle) • initial b* • planned 11 m, possibly 6 m in IR1 and IR5 (will require additional setup time for squeeze) • cross sections • inelastic xsec @450 GeV: 40 mb • W xsec@450 GeV: 1nb • Z xsec@450 GeV: 100 pb • assumed: 50% of daytime in physics • assumed: operational efficiency 60%

  9. Expected Performance 450 GeV assume 50% machine availability

  10. Stage I IV II III Install Phase II and MKB Hardware commissioning Machine checkout Beam commissioning 75ns ops 25ns ops I 25ns ops II 43 bunch operation ? No beam Beam Beam • Pilot physics run • First collisions • 43 bunches, no crossing angle, no squeeze, moderate intensities • Push performance (156 bunches, partial squeeze in 1 and 5, push intensity) • 75ns operation • Establish multi-bunch operation, moderate intensities • Relaxed machine parameters (squeeze and crossing angle) • Push squeeze and crossing angle • 25ns operation I • Nominal crossing angle • Push squeeze • Increase intensity to 50% nominal • 25ns operation II • Push towards nominal performance Staged Plan Overview

  11. 17

  12. 1 month min.

  13. (stage 2)

  14. design

  15. Staged Approach: Timeline

  16. Stage I II III Hardware commissioning 7TeV Machine checkout 7TeV Beam commissioning 7TeV 43 bunch operation 75ns ops 25ns ops I Shutdown No beam Beam III Shutdown Machine checkout 7TeV Beam setup 25ns ops I Install Phase II and MKB Beam No beam Staged commissioning plan for p@7TeV 2008 2009

  17. Sub-phase Bunches Bun. Int. beta* Luminosity Time Int lumi first Collisions 1 x 1 2 x 1010 18 m 4 x 1027 12 hours 0.15 nb-1 repeat ramp - same conditions - - - - 2 days @ 50% 0.3  nb-1 multi-bunch at injection & through ramp - collimation - - - - 2 days - physics 12 x 12 3 x 1010 18 m 1 x 1029 2 days @ 50% 8 nb-1 physics 43 x 43 3 x 1010 18 m 3.8 x 1029 2 days @ 50% 30  nb-1 commission squeeze – single beam then two beams, IR1, IR5 - - - - 2 days - measurements squeezed - - - - 2 day - physics 43 x 43 3 x 1010 10 m 7 x 1029 3 days - 6 hr t.a. - 70% eff. 75 nb-1 commission squeeze to 2m collimation etc. - - - - 3 days - physics 43 x 43 3 x 1010 2 m 3.4 x 1030 3 days - 6 hr t.a. - 70% eff. 0.36 pb-1 commission 156 x 156 - - - - 1 day physics 156 x 156 2 x 1010 2 m 5.5 x 1030 2 days - 6 hr t.a. - 70% eff. 0.39 pb-1 physics 156 x 156 3 x 1010 2 m 1.2 x 1031 5 days - 5 hr t.a. - 70% eff. 2.3 pb-1 29 days total Pilot physics

  18. ~ 140-160 days for physics per year Not forgetting ion and TOTEM operation Leaves ~ 100-120 days for proton luminosity running ? Efficiency for physics 50% ? ~ 50 days ~ 1200 h ~ 4 106 s of proton luminosity running / year Breakdown of a Normal Year of Operation Breakdown of a normal year 7-8

  19. I-LHC Commissioning • I-LHC performance limited to 50% of nominal beam intensities due to collimation system inefficiency and Bound Free Pair Production (BFPP) • Charmonix: • Pb commissioning in SPS in spring 2007 (competing with high intensity protons) • 1st Pb operation in LHC end of 2008 after pp run (allow cool down!) • delays in the PS and SPS imply 1st Pb in LHC not before 2009 • switching time pp-PbPb: somewhere between few days and 3 weeks • keep optical configuration for Pb close to proton operation to minimize switching time (RHIC: ~2 weeks) • earlier commissioning of ions is being discussed

  20. Switching Time for “early ions” • Pb ions have the same rigidity as protons • assume reasonable reproducibility, keep from p-run • injection • 1st turn • ramp • leave squeeze IR2 to similar b* as already used in IR1&5 (biggest item!) • don’t change magnetic optics • can keep RF capture and instrumentation setup as for p • use optimistic estimate (as used for p) • would give about 4 days (minimum)

  21. Ions in the LHC • Start with early ion scheme (62 bunches instead of 592, 7 107 ions per bunch) • Will have to • Set up RF capture • Commission essential instrumentation • Commission squeeze in IR2 • 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

  22. LHC critical tasks • Machine Protection System (MPS) • LHC cannot operate without • depends on various other systems • collimation • early stages • phase II • ions • radiation protection (RP) • stage 1,2,3 • nominal • Many more: • beam dumps • orbit control • beam instrumentation • gap cleaning • etc. etc.

  23. Stored energy in MJ Beam 450 GeV 7 TeV single pilot 5×109 0 0.006 beam of 1012 0.07 1.1 43 bunches of 4×1010 0.12 1.9 156 bunches of 4×1010 0.45 7.0 936 bunches of 4×1010 2.70 42.0 2808 bunches of 4×1010 8.09 125.9 2808 bunches of 1.15×1010 23.27 362.0 ~ stored energy of SPS, HERA, TEVATRON MPS: Stored energy • Stored energy alone is not the whole story, the beam size is also important ! • The failure mechanism plays also an important role for damages: Impact angle and time-constant

  24. Shot Intensity / p+ A 1.2×1012 B 2.4×1012 C 4.8×1012 D 7.2×1012 Based on those results we have adopted for the LHC a limit for safe beams @ 450 GeV of: 1012 protons with nominal emittance limit for safe beams @ 7 TeV: 1010 p with nominal emittance MPS: Damage test results TT40 damage test presented by V. Kain at Chamonix 2005: • Melting point of Copper reached for  2.5×1012 p [beam impact  to target surface]. • Results agree with estimates based on FLUKA simulations. A B D C

  25. The LHC Collimation Challenge • LHC Collimation System: hardware device designed to protect the ring elements from beam losses (without getting destroyed themselves!), the main features of such a system are: • Halo Cleaning: beam induced quenches of superconducting magnets are to be avoided => out of 2x105 protons lost at the collimators at 7 TeV, not more than 1 proton may escape and impact on any given meter of the LHC cold aperture • Protection: passive protection of the machine aperture against abnormal beam loss; beam loss monitors at the collimators detect unusually high loss rates and generate a beam abort trigger. • Problem: almost NOTHING survives the impact of the LHC full beam (including collimators). Even if there's no incident of full impact, collimators will be very radioactive => how to repair/replace anything?

  26. The LHC Type Collimator Collimators are made of carbon to increase their chance of survival (but this will also decrease the collimation efficiency) About 100 collimators in the LHC!!

  27. Bun-ches Bunch Intensity [1010 p] Total Intensity [1014 p] Loss rate for =0.2 h [p/s] One pilot bunch 1 0.5 0.00005 6.9E+06 1 10 10.0 0.01000 1.4E+09 43 bunches 43 4.0 0.01700 2.4E+09 Scenario I: 156 bunches 156 4.0 0.06200 8.7E+09 Scenario II: 156 bunches 156 9.0 0.14000 2.0E+10 Scenario 75 ns 936 4.0 0.37000 5.2E+10 Scenario I: 25 ns 2808 4.0 1.10000 1.6E+11 Scenario II: 25 ns 2808 5.0 1.40000 2.0E+11 Nominal 25 ns 2808 11.5 3.20000 4.5E+11 Quench limit for continuous losses @ collimation: 450 GeV  ~ 2.2 × 1010 p/s 7 TeV  ~ 4.5 × 108 p/s Collimators: Commissioning Scenarios • Official scenarios: • Intensity is an important parameter but not comprehensive! • Important: • Beam loss rate:Rloss≈ Itotal / Lower beam lifetime initially?! • Number of important failures:Bathtub curve: most failures initially. Redundancy more important for commissioning? no nom. bunch

  28. RP Quantities • Prompt Radiation (during operation,Counting Rooms) • Induced Radioactivity • Residual Dose Rates (Maintenance) • Material Activation (Zonage, Waste) • Releases • Air Activation & Control => IR7 (e.g., dose to critical groups) • Water Activation & Control(e.g., demineralised water circuit)

  29. RP: Intensities/Losses – Startup Expected losses are an educated guesses, however are subject to related uncertainties with respect to loss patterns and the final numbers (and location) of lost particles.

  30. Area Classification –Beam Off STAGE 1 RELAXED SITUATION ??? Controlled Areas (Collimation, Triplets,…) Supervised Areas:(Access galleries,…) IR7 Stage 1

  31. Summary • Many different scenarios and schedule options • 450 GeV Engineering run in 2007 • Pilot Run in 2008 • no ions scheduled before end of 2008 (2009 likely depending on injectors) • a lot of challenges • machine protection, radiation, collimation, machine parameters, …

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