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LHC Machine Status

LHC Machine Status. CERN-JINR Meeting, 11 October 2010 P. Collier (On behalf of the LHC team and international Collaborators). LHC Startup – Autumn 2009. November 20 th 2009 First beams injected and circulating November 29 th 2009 Both beams accelerated to 1.18 TeV simultaneously

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LHC Machine Status

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  1. LHC Machine Status CERN-JINR Meeting, 11 October 2010 P. Collier (On behalf of the LHC team and international Collaborators)

  2. LHC Startup – Autumn 2009 • November 20th 2009 • First beams injected and circulating • November 29th 2009 • Both beams accelerated to 1.18 TeV simultaneously • December 8th 2009 • 2x2 bunches accelerated to 1.18 TeV • First collisions at 2.36 TeV cm! • December 14th 2009 • Stable 2x2 at 1.18 TeV • Collisions in all four experiments LHC - highest energy collider Limited to 2 kA in main circuits (1.18 TeV) during deployment and testing of new Quench Protection System

  3. Commissioning and Running Scenario 2010/2011 • Following the technical discussions in the Chamonix workshop the CERN management and LHC experiments decided on the following Running scenario: • Run at 3.5TeV/beam with a goal of reaching and integrated luminosity of around 1fb-1 by the end of 2011. • This implies reaching a peak luminosity of 10+32 in 2010 • Then consolidate the whole machine for operation at 7TeV/beam during a long shutdown in 2012 • From 2013 onwards the LHC will be capable of the maximum Energy and Luminosity. The Primary goal for 2010

  4. Startup 2010 At this point there was a pause in operation of the machine for Physics in order to setup the machine for stable operation with nominal intensity per bunch (~1x10+11)

  5. Progress by the end of May 2010

  6. Operation May-August 2010 Essentially commissioning of injection, damper and RF, optics, setting up the collimation and machine protection systems and re-qualification for high bunch intensities

  7. Optics Beta-Beating Measurements through the year show an excellent reproducibility For the re-commissioning work in July, global corrections of the optics were done before starting the collimation set-up. Impressive results: Stable 10-20% beta beating around the machine

  8. Collimators Jaw Positions set using beam-based alignment at several points in the cycle and functions defined between them: Injection, High energy, squeezed optics (separated), squeezed optics (collisions) • At all times and conditions the hierarchy of the collimators and protection devices must be maintained. • Many dedicated qualification checks needed each time the operation cycle is significantly changed: • Betatron losses, • Off momentum losses, • Asynchronous dump tests

  9. Provoked vertical beam loss on beam 1 Momentum Cleaning Dump Protection Col. IR2 IR5 IR8 IR1 Collimation Team Cleaning Efficiency ~99.99%

  10. Crossing 2pb-1 Setup of high intensity bunches Peak Luminosity ~10+31

  11. 2 Weeks in August • Remarkable machine availability: impressive performance of cryogenics, QPS, converters, RF, instrumentation, collimators, injectors… • Very effective use of available time 25b 48b 50b

  12. Move to Bunch Trains • To make further progress it is necessary to pass to bunch trains • Decision made to pass to 150ns bunch trains from the injectors • Can potentially fill the LHC with 400+ bunches • But Increasing numbers of bunches to inject • Needed new optimization and checks of the injection process • Crossing angle needed throughout the operational cycle • Re-optimization and qualification of the collimation and machine protection systems • Especially the tertiary collimators around the experiments • Long-range beam-beam checks for the size of the crossing angle bumps needed • Smaller angles than nominal needed 170mR at injection, reduced crossing angle through the squeeze. • Opportunity taken to speed up the ramp 2A/s -> 10 A/s

  13. Ramping Faster • Ramp reduced from 46 to 16 minutes • Feedback on Tunes and orbit in the ramp and squeeze • Feed-forward of Q,Q’ |c| and orbit based on measurements • Ramp and squeeze is very reproducible …

  14. Crossing Angles

  15. Operation with Bunch Trains 22-Sep-2010: 24 bunches per beam13.5 h – ~170 nb-1 Peak Luminosity ~5x10+30 08-Oct-2010: 248 bunches per beam6.5 h – ~1700 nb-1 Peak Luminosity 8.8x10+31 • Progressively stepped up in number of bunches • Units of 48 bunches • 3 full cycles/dumps and around 20h of physics per step

  16. Performance to-date Presently Running with 248 bunches (1x10+11 ppb). Peak luminosity recorded = 8.8x10+31 cm-2s-1 Best Physics fill recorded 2.3pb-1 (200 bunches, in 13 hours)

  17. Next Steps • Increase to 344 bunches (2 more steps!) • Assuming we manage to follow this plan, by end of W41 we should collect another ~20-25 pb-1. • If the reserve is used for physics, with 6 fills per week it is possible to collect ~40 pb-1more since for 350 bunches fills deliver ~3-4 pb-1 per 12 hours. 104 200 296 Reserve! 248 344 152 3 ½ weeks of stable Ion operation Technical Stop

  18. Heavy Ion Run Parameters Initial interaction rate: 100 Hz (10 Hz central collisions b = 0 – 5 fm) ~108 interaction/106s (~1 month)

  19. Conclusions • All key systems performing remarkably well & there are some hugely complex systems out there. • Some commissioning still required, issues still to address • And NB there are still problems • Handling dangerous beams already - have to remain vigilant at all times (and not get carried away) • Performance with beam (losses, lifetimes, luminosity, emittance growth etc.) is very encouraging • Machine availability is excellent – the hard work of numerous teams • Almost reached 1032cm-2 s-1 our goal for the end of the year- just 10% to go!!!! • We are already looking ahead to the operating conditions next year – some studies to help decide this will take place this year.

  20. Additional Slides

  21. Stored Beam Energy

  22. Bunch Train Bumps ATLAS ALICE CMS LHCb B1 Hor 10 mm B1 Vert B2 Hor B2 Vert

  23. UFOs (Unidentified Falling Objects) • On 7th July we observed the first occurrence of fast beam loss events in the super-conducting regions of the ring: • Fast beam loss at a SC magnet over 0.5-2ms • Most events during stable beams: no lifetime issue before the event… • Loss at regions of very large aperture > 40 beam sigma (collimators between 6 and 15 sigma). • Hypothesis that it is probably ‘dust’ particles falling into the beam • Estimated size ~100 mm think Carbon-type object. • Two events in perfect coincidence (time & space) with TOTEM roman pot movements make this hypothesis rather convincing. LHCb IR7 IR1 Arc Arc Seem to be related to Intensity*Time s Time evolution of loss 1 bin = 40 ms 0.5 ms Dump trigger Excluded Totem UFOs

  24. High Backgrounds in recent fills • Vacuum activity in the common beam chamber of all experiments. • Local pressure bump around ± 60 m from the IP. • Uncoated segment of vacuum chamber at the warm-cold transition of inner triplets • Pressure rise driven by the presence of both beams • Higher backgrounds. • Driven by beam and bunch intensity • Possibly higher order mode heating from the beam. • Possibly due to synchrotron light heating desorption D1/D2 and Quads • Possibly Electron Cloud • NOT due to some beam losses as nothing on BLMs • Same order of magnitude everywhere (towards 10-7 mbar). • Gets worse when beam intensity goes up • Improves when running at same beam intensity • Cleaning effect • Valves will close if p > 4·10-7 mbar in 2 out of 3 gauges. Still ok. 1:30 – Ramp 2:00 – Squeeze 2:30 - Collide

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