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Status, Schedule, and Future of LHC Accelerator

Status, Schedule, and Future of LHC Accelerator. Frank Zimmermann Annual Meeting of Japanese Physical Society Kinki University, Osaka, 24 March 2008. outline features status & schedule upgrade plans. LHC features. Large Hadron Collider (LHC). proton-proton collider

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Status, Schedule, and Future of LHC Accelerator

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  1. Status, Schedule, and Future of LHC Accelerator Frank Zimmermann Annual Meeting of Japanese Physical Society Kinki University, Osaka, 24 March 2008

  2. outline • features • status & schedule • upgrade plans

  3. LHC features

  4. Large Hadron Collider (LHC) proton-proton collider next energy-frontier discovery machine c.m. energy 14 TeV (7x Tevatron) design luminosity 1034 cm-2s-1 (~100x Tevatron) start of beam commissioning in 2008 LHC nominal luminosity was pushed in competition with SSC

  5. LHC s.c. dipole magnet – 8.33 T model 2007 2006

  6. LHC magnetic cycle beam dump energy ramp coast coast 7 TeV 8.33 T start of the ramp injectionphase preparation and access 450 GeV 0.54 T L.Bottura, R.Schmidt

  7. LHC powering in 8 sectors 5 Powering Sector: 154 dipole magnets about 50 quadrupoles total length of 2.9 km 4 6 DC Power feed LHC 7 3 Octant DC Power 27 km Circumference • Powering Subsectors: • long arc cryostats • triplet cryostats • cryostats in matching section 8 2 1720 circuits (1695 cold, 217 with current >4000A) for comparison - HERA: 1 main circuit, 90 cold corrector circuits, 20 times "easier” 1 Sector P.Proudlock, R. Schmidt, K.-H. Mess

  8. ramping current in string of dipole magnets • LHC powered in eight sectors (154 dipole magnets each) • time for energy ramp: ~20-30 min (energy from the grid) • time for discharge: ~the same (energy back to the grid) Power Converter Magnet 1 Magnet 2 Magnet i Magnet 154 R. Schmidt

  9. key LHC parameters: • 1.15x1011 protons per bunch • 2x2808 bunches, 25 ns bunch spacing • 7 TeV proton energy • energy stored in 2 beams: >0.7 GJ • energy stored in magnets: ~10 GJ • →machine & magnet protection crucial • → many tests & checks necessary during hardware & beam commissioning • → phased commissioning

  10. total stored energy=11 GJ at 30 knots K.H. Mess, Chamonix 01

  11. challenge: energy stored in the beam at less than 1% of nominal intensity LHC enters new territory. R. Assmann, PAC2003

  12. temperature rise in superconducting cable after a “quench” (transition from super-conducting to normal-conducting state) DT/Dt > 5x103 K/s ! R. Schmidt

  13. quenches are initiated by an energy ~ mJ (1000 protons at 7 TeV) • movement of the superconductor by several m (friction and heat dissipation) • beam losses • failure in cooling to limit temperature increase after quench • quench must be detected • energy is distributed in the entire magnet by force-quenching the coils using quench heaters • the magnet current has to be switched off within << 1 s R. Schmidt

  14. LHC quench protection R. Schmidt • when one magnet quenches, quench heaters are fired for this magnet • current in quenched magnet decays in about 200 ms • the current in all other magnets flows through the bypass diode that can stand the current for about 100-200 seconds; resistors are switched in series Power Converter resistors for energy extraction Magnet i Magnet 1 Magnet 2 Magnet 154 bypass diode

  15. bypass diode energy extraction system in LHC tunnel switches - for switching resistors into series with magnets resistors absorbing the energy F.Rodriguez-Mateos, K.Dahlerup-Petersen, R. Schmidt F.Rodriguez-Mateos, D.Hagedorn, R. Schmidt

  16. status & schedule • hardware commissioning of sectors 78 and 45 • cryogenics, powering tests, quenches • route of fastest progress

  17. prior to installation all s.c. magnets were tested in “SM18”

  18. SM18 cold magnet tests V. Chohan

  19. hardware commissioning evolution so far July. ‘07 Feb‘08 Jan. ‘07 Powering Test S45 Cooldown/Warm up S45 Cooldown/Warm up S78 26th Nov. 19th Feb 08 PT S78 20th April 11th Jul.07 Sector 4-5 , Nov 07 - Feb 08 Sector 7-8 , May – June 2007

  20. S. Claudet Cool-down Global tuning And DFBs commissioning Powering (Big gain expected) (2-3 wks w.r.t 9 wks) 7 weeks to cool down to 1.9 K, hope to speed up to 4 weeks, design was 2 weeks

  21. LHC sector 45: 1st cool-down Cool-down to 1.9K Cryogenic tuning 1st leak and repair Powering tests 2nd leak and repair >17 weeks to cool down to 1.9 K

  22. Target for LHC operation Target for HWC cryogenics availability after cool-down & (DFB tuning or ELQA) S78: 85% (LSS), 66 % (ARC) S45: 93% (LSS), 63 % (ARC) S45: MTBF=11 days, MTTR=2 days considering independent origins recovery after resistive transition (quench) of 1 cell: 2-3 hours for I < 9 kA (expected) 10-20 hours for I > 9 kA (4-5 h expected) full sector: 2 day recovery fast discharge (no quench): 2 h recovery

  23. LHC cool-down schedule 12 23 34 45 56 67 78 81 Feb. March April May June K. Foraz, 06 March 2008

  24. S45 powering tests S78: only 30% of circuits released, max. dipolecurrent 2 kA (1.2 TeV) Baseline 7TeV Done 6TeV Target ~60 test/wday Boris Bellesia Successful test steps dipole&quad current > 10 kA (5.8 TeV) W2 W48 W50 W52 W8 W6 W4 w9 Cryo conditions B. Bellesia, eLTC, & R. Saban – eLTC. March 2008

  25. 2ppm other S78 & S45 circuit tests « all » magnetramp to 5.3 TeV tracking of 3 main circuits F. Bordry - eLTC 2008 -March 2008 Sector 45 is fully commissioned to below 3 TeV partially commissioned to 5 TeV all main circuits large part 600A circuits partially commissioned to 6 TeV all main circuits few 600A B. Bellesia, R. Saban – eLTC, March 2008 b* squeeze test F. Bordry, R. Alemany, M. Lamont, eLTC 2008 - March 2008

  26. inner triplet complex system with interleaved circuits never tested on superconductive loads crucial for machine operation will require time before reaching required performance (high precision on highly complex system) F. Bordry - eLTC 2008 -March 2008

  27. 26R4 A B C A B C 27R4 natural dipole quenches in S45 1 min 9789 A (5.71 TeV) 1 s 9859 A (5.75 TeV) 2 min 1 min 1 min 10274 A (5.99 TeV) 1 min 1 min 2 min 1 min

  28. correlation of S45 quenches with SM18 3 1 2 large detraining SM-18: 175 quenches to reach 12 kA in all 154 dipoles ArjanVerweij & Robert Flora, Review of Sector 45 Commissioning, 28 February 2008

  29. comments on dipole quenches • unexpectedly fast quench propagation (one case) • interesting (new) phenomenon of quench recovery and magnet re-quenching • more pronounced than expected detraining effect for two magnets • all three quenches occurred in magnets from same manufacturer and within a few serial numbers (3176, 3180, 3191) A. Siemko, MARIC 19 March 2008

  30. S45 natural quenches - all magnets *: nominal not reached other cold magnets quench too … A. Verweij & R. Flora, Review of Sector 45 Commissioning, 28 February 2008

  31. optimistic LHC schedule • whole ring cold by mid June • inject first beam in early July • make compromise between speed of commissioning & collision energy in order to • get to physics as early as possible & to give operations teams some margin for error during early operation • beam energy between 5 and 6 TeV; value to be decided by end of April • if all goes well, collisions in late August or September?!

  32. let us go back 15 years … 1993 forecast for high-energy colliders “2008 view” → †1993 → †2004 → †2004 → 2025-30 “ILC” 2008

  33. how can we achieve LHC beam this summer? • test automation & parallelism • simplification of test plan • good & stable cryogenics conditions • lower commissioning energy A. Vergara – eLTC 2008

  34. lower commissioning energy ~5 TeV • no quenches up to 5 TeV • (based on SM18 & S45) • quench recovery much faster below • 9 kA (~5 TeV) magnet current • saving in powering tests (200-300 A • sufficient for most 600 A circuits) • beam operation easier at 5 TeV • (magnets much farther away • from quench limit)

  35. quench probability dipole quenches extrapolating from SM18 cold magnet quenches extrapolated from S45 numbers per sector A. Siemko, MARIC 19 March 2008 for <7 T: quench probability  1%, below 6.5 T <0.1% (no quenches) A. Verweij & R. Flora, Review of Sector 45 Commissioning, 28 Feb. 2008

  36. quench with fast loss of ~5106 protons Bc 8.3 T Tc quench with fast loss of ~5109 protons 0.54 T 1.9 K operational margin of a superconducting magnet Applied Field [T] Bccritical field energy margin before quench vs. beam energy QUENCH Tccritical temperature Temperature [K] 9 K R. Schmidt M. Calvi, A. Siemko, R. Schmidt

  37. shorter powering tests: main circuits maximum current 1 kA 3 kA 6 kA 2 kA 4 kA 5 kA 8 kA 11 kA 9 kA 10 kA 7 kA 12 kA Quenches RB PCC-PLI PNO RQF+ RQD PCC-PLI PNO Injection 7 TeV 3 TeV 5 TeV 1 TeV 2 TeV Antonio Vergara – eLTC 2008

  38. shorter powering tests: main circuits commissioning days 1d 2d 3d 4d 5d 6d 9d 8d 10d 11d 7d 12d PCC-PLI PNO RB RQF+ RQD PCC-PLI PNO Quenches 5 TeV Injection 7 TeV 2-3 TeV 1 TeV Antonio Vergara – eLTC 2008

  39. shorter powering tests: all circuits commissioning days 1d 2d 3d 4d 5d 6d 9d 8d 10d 11d 7d 12d 5 TeV 7 tev RB RQ 5 TeV 7 tev IPQ 5 - 7 TeV 600A 5 TeV 7 tev commissioning time may now be limited by 600-A circuits Antonio Vergara – eLTC 2008

  40. back-up : sector test 3 options M. Lamont, eLTC, March 2008

  41. beam commissioning strategy for protons (estd. 2005) Stage A D B C No beam Beam • Pilot physics run • First collisions • 43 bunches, no crossing angle, no squeeze, moderate intensities • Push performance • Performance limit 1032 cm-2 s-1 (event pileup) • 75ns operation • Establish multi-bunch operation, moderate intensities • Relaxed machine parameters (squeeze and crossing angle) • Push squeeze and crossing angle • Performance limit 1033 cm-2 s-1 (event pileup) • 25ns operation I • Nominal crossing angle • Push squeeze • Increase intensity to 50% nominal • Performance limit 2 1033 cm-2 s-1 • 25ns operation II • Push towards nominal performance R.Bailey, eLTC, March 2008

  42. during squeeze, triplet becomes LHC aperture limit for b*<6 m T. Weiler inner triplet becomes aperture limit must close collimators for b* < 6 m! change in “n1”: about 2.5 s per m in b* in relevant range!

  43. upgrade plans

  44. Two Strong Reasons for LHC Upgrade J. Strait 2003 hypothetical luminosity evolution 1) after few years, statistical error hardly decreases 2) radiation damage limit of IR quadrupoles (~700 fb-1) reached by ~2016  time for an upgrade!

  45. A Third Reason: Extending the Physics Potential of LHC • 10x higher luminosity extends discovery range by ~ 25% in mass & precision by a factor of ~2 Examples studied in detail • Electroweak Physics • Production of multiple gauge bosons (nV 3) • triple and quartic gauge boson couplings • Top quarks/rare decays • Higgs physics • Rare decay modes • Higgs couplings to fermions and bosons • Higgs self-couplings • Heavy Higgs bosons of the MSSM • Supersymmetry (up to masses of 3 TeV) • Extra Dimensions • Direct graviton production in ADD models • Resonance production in Randall-Sundrum models TeV-1 scale models • Black Hole production • Quark substructure • Strongly-coupled vector boson system • WLZL g WLZL , ZLZL scalar resonance, W+LW +L • New Gauge Bosons Include pile up, detector… hep-ph/0204087 Albert de Roeck, Bodrum 2007

  46. upgrade players PAF CERN Council Strategy Group

  47. 2001 upgrade feasibility study

  48. constraints • collimation & machine protection - quenches, cleaning efficiency, impedance → limit on beam current • electron cloud - heat load in s.c. magnets, instabilities, emittance growth → limit on beam current, bunch pattern • beam-beam interaction -head-on, long-range (LR), crossing angle → LR compensators, crab cavities, ES dipoles

  49. electron cloud in the LHC schematic of e- cloud build up in the arc beam pipe, due to photoemissionand secondary emission [F. Ruggiero]

  50. long-range beam-beam 30 long-range collisions per IP, 120 in total → minimum crossing angle, ↑ with 1/b*1/2

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