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LHC : Status, Prospects and Plans

LHC : Status, Prospects and Plans. “ LHC:  the status, the  projections for this year, and the possibilities for the restart after LS1..” . Paul Collier For the LHC Team. Acknowledgements to many people who helped preparing these slides – and especially Mike Lamont.

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LHC : Status, Prospects and Plans

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  1. LHC : Status, Prospects and Plans “LHC:  the status, the projections for this year, and the possibilities for the restart after LS1..” Paul Collier For the LHC Team Acknowledgements to many people who helped preparing these slides – and especially Mike Lamont Paul Collier – LHC: Status, Prospects and Plans{lans

  2. A quick look back: 2011 at a glance 50 ns 75 ns Increase Number of Bunches Intermediate energy run, technical stop, scrubbing MD, technical stop Mini-Chamonix MD, technical stop MD, technical stop Emittance Reduction (Injectors) b* = 1m Paul Collier – LHC: Status, Prospects and Plans{lans

  3. 2011 • Successfully wrestled with: • Total intensity • Bunch spacing • Bunch intensity • Emittance • b* & aperture • Good performance from working on all available parameters • Definitely exploring the effects of high intensity beams: • SEUs, beam induced heating, vacuum instabilities… • Operational efficiency suffering as a result Paul Collier – LHC: Status, Prospects and Plans{lans

  4. Of note – what was achieved • Operational robustness • Precycle, injection, 450 GeV, ramp & squeeze & collisions routine • Machine protection • Unpinned by superb performance of machine protection and associated systems • Rigorous machine protection follow-up, qualification and monitoring • Routine collimation of 110 MJ LHC beams without a single quench from stored beams. Paul Collier – LHC: Status, Prospects and Plans{lans

  5. What we discovered in 2011 • The LHC injectors can provide a significantly higher brightness beam than foreseen (50ns) • Nb/e ≥ 0.77x10+16 cf “nominal” performance (25ns) = 0.33 (1.15/3.5) • The LHC can handle very high bunch intensities • head-on beam beam not a significant problem (yet) • Leveling the luminosity down for LHCb does not pose a significant problem for the machine • The control of the machine parameters and the quality of the alignment means that the available aperture in the triplets is higher than expected • can be used for larger crossing angle, or lower b* • Partially exploited already during 2011 to go from 1.5m down to 1m • 50ns bunch spacing did not require too much “scrubbing” against electron cloud • and the memory was preserved over the 2011/2012 TS. • Electron cloud more of a problem for 25ns beams in LHC (and SPS) • UFO’s exist … but appear to clean away Paul Collier – LHC: Status, Prospects and Plans{lans

  6. Aperture in the Inner Triplets at 3.5 TeV 2011’s “platinum mine” The Combination of the larger effective aperture and the lower emittance beam coming from the injectors (for 50ns) opens the possibility that the collimators can be put to “Tight” settings (to protect this aperture) whilst squeezing the b* to 0.6m. Very significant gain in Luminosity (x1.7) We got 4-6 sigmas more than the expected 14 sigma Triplet aperture compatible with a well-aligned machine, a well centred orbit and a ~ design mechanical aperture ~3 cm Stefano Redaelli ~600 m • This Margin can be used to increase the Crossing Angle, and/or reduce the b* • Together with collimation, this opened the way to a squeeze to 1m in 2011 and potentially even further in 2012 Paul Collier – LHC: Status, Prospects and Plans{lans

  7. Electron Cloud in the LHC schematic of e- cloud build up in the arc beam pipe, due to photoemissionand secondary emission Strong function of parameters such as: Bunch Spacing, Bunch intensity, size of the beam pipe and surface emission properties of the material. Threshold effect leads to build up of electrons inside the vacuum chamber: Heat load (in cold sections), Vacuum pressure rise and beam instabilities Paul Collier – LHC: Status, Prospects and Plans{lans

  8. E-Cloud – impact on the beam Tests during dedicated studies (25ns beams) show the e-cloud builds up along a batch of bunches and provokes beam size growth and poor lifetime In the warm sections of the machines solenoids have also been wrapped around the beampipe … Significant improvement, but can’t be done in the cold sections! The main solution is to condition the surface by electron bombardment – “scrubbing” Very effective – but takes significant amounts of dedicated beam time (and becomes less effective as the scrubbing proceeds) Paul Collier – LHC: Status, Prospects and Plans{lans

  9. UFO’s in the LHC 4513 arc UFOs (≥cell 12) at 3.5 TeV between 14.04. and 31.10.2011. Signal RS01 > 1∙10-3Gy/s. • Since July 2010, 35 beam dumps due to UFO’s • Loss Duration: about 10 turns • Locations: evenly spread around the whole machine with a concentration in the Injection kickers • In 2011: 16,000 candidate UFO events below the BLM dump thresholds found UFO on 23.08.2010 • 1/x distribution of BLM signals (UFO strength) well explained by expected dust particle size distribution • Seems to be a (strong) dependence on bunch spacing and possibly beam energy Paul Collier – LHC: Status, Prospects and Plans{lans

  10. UFOs in 2011: Cleaning? TS #2 (09. – 13.05.2011) TS #3 (04. – 08.07.2011) 5242 candidate arc UFOs (≥ cell 12) during stable beams between 14.04. and 31.10.2011. Fills with at least 1 hour stable beams are considered. Signal RS04 > 2∙10-4Gy/s. 1380 bunches TS #4 (29.08 – 02.09.2011) 25ns, 60b Decreaseof UFO rate from 10 to 2 UFOs/hourduringmonthswith 50ns operation Significantincrease in rate during 25ns MD‘satthe end oftheyear (~10 UFOs / hour) Paul Collier – LHC: Status, Prospects and Plans{lans

  11. Stop Press : 2012 … 2011: Decreaseof UFO rate from≈10 UFOs/hourto≈2 UFOs/hour. 2012: About2-3 timeshigherUFO rate thanduringOctober 2011. Deconditioning? Higher Energy?? (apparent rate reductionwith time in 2012 ...) TS #2 (09. – 13.05.2011) TS #3 (04. – 08.07.2011) TS #4 (29.08 – 02.09.2011) Ion runWinter TS, etc. (31.10.2011 – 05.04.2012) 1380 bunches 1380 bunches 2011 2012 25ns, 60b 5696 candidate arc UFOs (≥ cell 12) during stable beams since 14.04.2011. Fills with at least 1 hour stable beams are considered. Signal RS04 > 2∙10-4Gy/s. Paul Collier – LHC: Status, Prospects and Plans{lans

  12. 2011 to 2012 • Well organized, productive Xmas technical stop • Lot of R2E related work • Plus consolidation and improvements of many systems • Vacuum consolidation to address successfully diagnosed causes of instabilities in 2011 • Injection collimators issues diagnosed and understood - spare in preparation - fingers crossed in the meantime • Cool-down of machine exactly on schedule • Very smooth hardware commissioning including careful quench-less commissioning of main circuits to 4 TeV • Well oiled Machine checkout final tests and preparation for beam Paul Collier – LHC: Status, Prospects and Plans{lans

  13. Preparation for 2012 Run • Highest Priority • Sufficient Integrated Luminosity to discover (or exclude the Higgs before the Long Shutdown – Target set at 15 fb-1 • Plans • Stick with 50ns bunch spacing 1380 bunches push the bunch intensity (with lowest possible emittance from the injectors) • Will mean high pile up in the experiments ~40 events/crossing • Increase beam energy from 3.5 – 4 TeV (+15% in Luminosity) • Check there is no risk from the splices • Reduce the b* in CMS and ATLAS to 0.6m (+60% in Luminosity) • Requires “Tight” collimator settings • b* = 3m in Alice and LHCb, Tilted Crossing in LHCb, Satellite-main collisions in Alice • Work on limiting the impact on radiation to electronics • Work on Turnaround time … • Hope that UFO’s are not an increasing problem Output of Chamonix and post-Chamonix Discussions Paul Collier – LHC: Status, Prospects and Plans{lans

  14. 2012 Bunch Spacing – 50ns or 25ns • 50ns • Operationally in good shape • 25ns • Not yet used operationally • Can fit 1380 bunches into the LHC • Can fit 2748 bunches into the LHC • Injectors can provide very high intensity per bunch at low emittance: • Ib ~1.6x10+11, e <2.0mm • Injectors cannot provide as high brightness bunches: • Ib ~1.2x10+11, e = 3.0mm • Problems with electron cloud instabilities are much less apparent • No need for a significant period of dedicated “scrubbing” • Emittance growth and lifetime problems due to e-cloud effects are very strong • A week of dedicated “scrubbing” needed. From the machine point of view 50ns operation in 2012 is clearly much better • Smaller Emittance means larger aperture – can run with b* = 0.6m • Larger emittance means that the b* is limited to 0.9m • Individual bunch intensity very high – but under control (2011) • Total intensity in the beam much higher. Limits from Vacuum, RF etc. Paul Collier – LHC: Status, Prospects and Plans{lans

  15. Why is the 50ns beam Brighter than 25ns? • The Brightness is determined primarily in the PS Booster • Each PSB bunch is split into 12 (in PS) to make the 25ns beam (6 for 50ns) • To get the same intensity per bunch in 25ns requires x2 the intensity in the PSB bunches! e vs. Ib for 50ns in PS Booster Emittance increases with intensity in the PS Booster … the brightness per bunch from the injectors will be lower for the 25ns beam -> but of course there are more bunches in LHC Paul Collier – LHC: Status, Prospects and Plans{lans

  16. Collimator Settings 2012 2012: tight settings Collimation hierarchy has to be respected in order to achieve satisfactory protection and cleaning. Aperture plus tight settings allows us to squeeze to 60 cm Roderik Bruce Paul Collier – LHC: Status, Prospects and Plans{lans

  17. What are “Tight” Collimator Settings 2.2 mm Paul Collier – LHC: Status, Prospects and Plans{lans

  18. 2012 – a ‘normal’ long year? ~150 days p-p Paul Collier – LHC: Status, Prospects and Plans{lans

  19. 50ns Performance Estimate from Chamonix 4 TeV, 50 ns, 1380 bunches, 1.6x10+11, 2.5 microns150 days of proton physics (assuming similar efficiencies to 2011) Steve’s Challenging target Paul Collier – LHC: Status, Prospects and Plans{lans

  20. Startup 2012 First beam injected: 14th March First Beam at 4TeV (New World Record!!): 16th March Squeeze to 0.6m b*: 18th March Acceleration of Single nominal bunches: 28th March First Stable Beams (3x3 bunches): 5th April 3 Weeks! Followed by a rapid ramp up in the number of bunches: 48, 264, 624, 1092, 1380 18th April Present Peak Performance (31/5/2012): Bunch intensity: 1.5x10+11 ppb in 1380 bunches Peak Luminosity: 6.5x10+33 cm-2 s-1 Total Integrated Luminosity: >4 fb-1 Best Fill: 0.25fb-1 in 22 hours Not too bad … but a number of issues have surfaced!! (The last 24 hours have been nothing to shout about) Paul Collier – LHC: Status, Prospects and Plans{lans

  21. Peak Luminosity Evolution (so far) Should never have Stopped! Impressive Ramp-up! Back in business – but it is not all plain sailing! MD, Technical Stop The injectors are important! Paul Collier – LHC: Status, Prospects and Plans{lans

  22. 2012 So Far • Smooth re-commissioning • Tight collimator setting operational • Squeeze to 60 cm OK • Excellent peak performance • Peak/delivery rates • Luminosity production hampered by • Injector beam quality (some foot shooting) • Machine availability – lots of little problems • Some fun with beam-beam instabilities, LHCb’s tilted crossing angle…. • Now settling down Paul Collier – LHC: Status, Prospects and Plans{lans

  23. B1 Bunches dropping out Soution: New Filling scheme with no ‘Private’ collisions in IP8 (and no non-colliding bunches in IP1 &5) Solves the problem for us … but not for you (to be revisited) • only losses in beam 1 and single bunch • ... and only bunches that collide exclusively in IP8 • it happens AFTER adjust, i.e. in stable beam condition • surprising emittance values • Single bunch head-tail instability probably driven by the increased impedance and not enough damping from the beam-beam Paul Collier – LHC: Status, Prospects and Plans{lans

  24. Production Running : up to 3rd June On track for 6fb-1 by the 19th June (beginning of next MD period) 1.05 fb-1 per week Paul Collier – LHC: Status, Prospects and Plans{lans

  25. Recent operational Efficiency Paul Collier – LHC: Status, Prospects and Plans{lans

  26. Rest of the year? No more magic tricks: Lpk~7x10+33 Just a question of maximizing the running Paul Collier – LHC: Status, Prospects and Plans{lans

  27. Lessons for the Future • Head on Beam-Beam is not (yet) a limitation • Actually beneficial to provide tune spread and damping! • Long-Range Beam has to be taken seriously • Small as possible emittances are good • Need to maintain good separation (otherwise bad lifetime) • Separation needed sets the crossing angle parameters • b* reach (aperture, collimation, optics) established • Separation levelling tested – and works for LHCb • Not so clear that can use it in ATLAS and CMS as well • Availability issues (SEU’s, vacuum, cryognicsetc) • Vigorous follow-up and consolidation. Paul Collier – LHC: Status, Prospects and Plans{lans

  28. 2013-2014 : LS1 • Consolidation of the machine to allow operation at full energy • Inter-magnet splice repair and design improvements • Complete pressure relief valve installation • Bring all elements to level needed for 7 TeV operation • Mitigation measures for Radiation to Electronics effects (move/shield/redesign) • Maintenance of all systems after 3 years of running. • Consolidation and first stage upgrades of the Detectors • New beam pipes in 3 of the 4 experiments • Maintenance repair and consolidation of the detector infrastructure • Additional detector components/upgrades • Duration • LHC Machine 20 months • ALICE 12-15 months • ATLAS 15 months • CMS 20 months New Vacuum Chambers • LHCb 12 months Huge Collaborative effort to get the work done in the time available Paul Collier – LHC: Status, Prospects and Plans{lans

  29. LS1 Schedule Other LHC Activities Fit around the splice repair Work on the rest of the complex if resources available… Short LHC Power testing already starts at the end of 2013!! Paul Collier – LHC: Status, Prospects and Plans{lans

  30. Restart after LS1 • The LHC will restart in Autumn 2014, Essentially as a new machine • All interconnects opened and repaired • Several (~20) magnets changed • Huge infrastructure works for R2E mitigation • New protection systems • Lots of new controls/ software • etc. etc. • What will be the likely running conditions • Beam Energy?  retraining the magnets • Bunch spacing?  conditions for the experiments • What performance can we expect? Paul Collier – LHC: Status, Prospects and Plans{lans

  31. Beam Energy after LS1 : Training the Magnets During the 2008 Hardware Commissioning all but 1 sector reached 5 TeV without a quench A training campaign in one sector reached 6.6TeV after about 30 Quenches (but progress was slow) Measurement Campaign Launched on the surface (Not in LHC!) Conclusion : Start LHC after LS1 at 6.5TeV (move slowly upwards in later years) <50 Paul Collier – LHC: Status, Prospects and Plans{lans

  32. Bunch Spacing after LS1 • We gain a factor 1.6 in luminosity going from 4 to 6.5 TeV • Without any increase to the performance, todays 50ns beam would give a peak luminosity of 1.1x10+34 cm-2 s-1 ! • But this would mean a pile up of >60 events per crossing!! • Not appreciated by you lot!!! • If we can get the same performance out of the 25ns beam we can run at a similar peak luminosity – but half the pile up At the moment we are racing for Luminosity in 2012 – but later we need to do some studies for the future and 25ns is high on the list! (Probably) Startup after LS1 with the 25ns bunch spacing Learn as much as possible about the issues in 2012 Allocate sufficient time for ‘scrubbing’ and commissioning during the startup Paul Collier – LHC: Status, Prospects and Plans{lans

  33. Injector Performance Reach after LS1 (1/2) Paul Collier – LHC: Status, Prospects and Plans{lans

  34. Injector Performance Reach after LS1 (2/2) • Potential for ~twice the nominal luminosity in LHC… H. Damerau – Chamonix2012 Paul Collier – LHC: Status, Prospects and Plans{lans

  35. Running Options 2015 (Option1) • Restart with 50ns • Assume an acceptable mean pile-up pf ~40 • Use separation or b* levelling to keep below this value • Recent experience indicates that separation levelling at high intensity might not be easy! • b* levelling complicated to do during stable beams • Not many possibilities to push the performance further – 50ns beam close to its limits Paul Collier – LHC: Status, Prospects and Plans{lans

  36. Running Options in 2015 (Option 2) • Restart with 25ns beams • It is the machine which limits the performance - not the pile up! • Injector performance today can give close to 10+34 in LHC • Many more possibilities for incremental increase in performance • Adopt the ‘low-emittance’ variant as soon as it is available. Looks like the best bet for everyone … But implies time during the startup Paul Collier – LHC: Status, Prospects and Plans{lans

  37. Potential Limitations – to watch Performance could be impacted by: • Radiation to electronics – SEU’s • In spite of work during LS1 … trying to stay ahead of the game • UFOs at higher energy & with 25 ns • More of them? Will they clean away?? • Will become ‘Harder’ and less quench margin? • Electron cloud & high energy & at 25 ns • Need more information • Emittance growth in physics • Total beam intensity limits in the LHC… • Have to wait and see … Life will get (even) more interesting! Paul Collier – LHC: Status, Prospects and Plans{lans

  38. 2015: Potential Performance • 150 days proton physics • 5% beam loss, 10% emittance blow-up in LHC • 10 sigma separation • 70 mb visible cross-section • * different operational model - caveat All numbers approximate! Paul Collier – LHC: Status, Prospects and Plans{lans

  39. Conclusions • 2012 performance, after some more experience, is looking encouraging, goals for year credible • LS1 Planning now well in hand – but tough times ahead! • Injector planning stabilizing • LINAC4 connection, LIU upgrades not until LS2 • Interesting improvement possible before • Towards HL-LHC beams after • After LS1, 25 ns is baseline with potential to reach ultimate luminosity certainly after, possibly before, LS2 • Levelled 50 ns remains an interesting option, particularly if there are total intensity limitations • Certainly not yet given Paul Collier – LHC: Status, Prospects and Plans{lans

  40. The Ultra-unofficial Higgs combination Thanks for your Attention!! Paul Collier – LHC: Status, Prospects and Plans{lans

  41. Spares Paul Collier – LHC: Status, Prospects and Plans{lans

  42. LHC Schedule 2012 Q1/Q2 Commissioning Scrubbing (postponed) Ramp-up MD & TS Paul Collier – LHC: Status, Prospects and Plans{lans

  43. 2012 LHC Schedule Q3/Q4 Proton-lead High beta* runs for ALFA and TOTEM, Van der Meer scans Paul Collier – LHC: Status, Prospects and Plans{lans

  44. So what is the Safe Operating Current for 2012? Probability of a splice burning increases at 4 TeV But the Risk is very low – there have been no beam induced high field quenches in the LHC since it started! Additional measures taken in addition to limit the impact of a splice burning Because of the work done in 2011 on the Protection systems (to remove non-beam induced quench mechanisms) And better control of the machine, the additional Risk of 4TeV over 3.5TeV is negligible. • Conclusions: • There is a slightly increased risk by running at 4TeV • Be conservative with beam loss monitor thresholds • Aim again for zero high field quenches. • If any occur – think again Paul Collier – LHC: Status, Prospects and Plans{lans

  45. 2012: Beam Energy • Despite correct splice resistance between SC cables, a 13 kA joint can burn-out in case of a quench, if there would be a bad bonding between the SC cable and the copper bus, coinciding with a discontinuity in the copper stabilizer So what is a Safe Operating Current for 2012? • Resistance measurements and -ray pictures have shown the presence of many of such defective joints in the machine, limiting the safe operating current This is why the LHC will be shutdown in 2013 … Paul Collier – LHC: Status, Prospects and Plans{lans

  46. Luminosity: Best Guess for the next 10 years Shut down to fixinterconnects and overcomeenergy limitation (LHC incident of Sept 2008) Shut down to overcomebeamintensity limitation (collimation, New Cryo P4,…) Inj. upgrade “Nominal” Operation, Energy, Luminosity IT Radiation Damage? Paul Collier – LHC: Status, Prospects and Plans{lans

  47. HL-LHC: The need for an Upgrade Around 2022 the Present Triplet magnets reach the end of their useful life (due to radiation damage) …and will anyway need replacing. In addition the Luminosity of the LHC will saturate by then Time for an upgrade! Paul Collier – LHC: Status, Prospects and Plans{lans

  48. How to do it … Work on the injectors (and LHC) to increase the beam brightness N/en Cannot reduce the bunch spacing – stick with 25ns (50ns), 2808(1404) bunches Use Crab cavities to recover the geometric reduction factor – and as a mechanism for Leveling Decrease the b* to 10-20 cm Implies new large aperture final focus quads but also implies lower value of Rθ There are a lot of inter-dependencies between parameters – and many implications for the Equipment. Paul Collier – LHC: Status, Prospects and Plans{lans

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