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Luminosity and time estimates

Luminosity and time estimates. Mike Lamont. Thanks for discussion: R. Assmann , R. Bailey, M. Ferro- Luzzi , S. Fartoukh , O. Bruning. Disclaimer. The future is a strange place Aim of the exercise is to establish some realistic numbers given accepted constraints

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Luminosity and time estimates

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  1. Luminosity and time estimates Mike Lamont Thanks for discussion: R. Assmann, R. Bailey, M. Ferro-Luzzi, S. Fartoukh, O. Bruning

  2. Disclaimer • The future is a strange place • Aim of the exercise is to establish some realistic numbers given accepted constraints • All numbers to be treated with a modicum of circumspection • Optimistic numbers can be treated as upper limits Luminosity estimates

  3. Some formulae Halving time to luminosity – 2 IPs Assume radiation damping compensates diffusion And then optimize fill length Following Ruggiero Luminosity estimates

  4. Luminosity estimates • Calculate peak luminosity given the usual inputs • Bunch current, number of bunches, emittance, beta*, crossing angle • Calculate luminosity lifetime given • Luminosity, cross-section • Beam-gas lifetime • IBS growth rates • Optimize fill length given an assumed turnaround time • Given fill length & luminosity lifetime – calculate integrated luminosity per fill • Multiply up Luminosity estimates

  5. Turn around time Physics to physics ~ 3 hour minimum. Assume 4 hours here – optimism bias Luminosity estimates

  6. Note: ramp down – precyclecombo • Perform ramp down of main bends, quads, IPQs, triplets etc. • Up to 40 minutes from 3.5 TeV values • At the same time precycle all other circuits • Sextupoles, correctors, compensators, warm magnets etc Luminosity estimates

  7. LEP • No-one ever thought it could be as smooth as: Less than one hour turn around (after 8 years’ optimization) Luminosity estimates

  8. Of course it wasn’t always as good as that Luminosity estimates

  9. Operation month/year After a year or so… • 30 days per month • 3 day technical stop & recovery • [~2 days machine development] • Absorbed into unavailability for this exercise • 60% machine availability • During which time we are dedicated to trying to do physics • 4 weeks of ions (plus one week setup) • Other requests e.g. Totem • Shutdown • Assume around 7 months proton physics per year • approx. 200 days, optimization possible with a 2 year cycle Luminosity estimates

  10. The Hubner factor • Standard method • Take schedule physics time (minus MD, scheduled stops etc.) • Take peak luminosity time number of seconds • Multiply by Hubner factor • Usually taken to be around 0.2 • Takes into account luminosity lifetime, turnaround, unplanned interventions etc • Here I have explicitly calculated luminosity lifetime, optimal fill length etc. • End up with a HF of around 0.3 • Long luminosity lifetime, long fills, 4 hour turn around • The LHC has to be good, rashly make the assumption that we can make it so. Luminosity estimates

  11. Out with the crystal ball Luminosity estimates

  12. 2010 to 2 MJ Jorg’s approved steps to 2 MJ Simple HF Luminosity estimates

  13. What you can TT40 Damage during 2004 High Intensity SPS Extraction / Goddard, B ; Kain, V ; Mertens, V ; Uythoven, J ; Wenninger, J Or what you can do with 2.9 MJ During high intensity extraction on 25/10/04 an incident occurred in which the vacuum chamber of the TT40 magnet QTRF4002 was badly damaged. The beam was a 450 GeV full LHC injection batch of 3.4 1013 p+ in 288 bunches, and was extracted from SPS LSS4 with the wrong trajectory 4.4 e12 at 3.5 TeV 88 bunches at 5 e10 Luminosity estimates

  14. 2010++ Massimo Giovannozzi et al Luminosity estimates

  15. 2011 3.5 TeV: run flat out at ~100 pb-1 per month 16% nominal Should be able to deliver around 1 fb-1 Luminosity estimates

  16. Beam beam tune shift Round beam approximation 7 e10 gives around 0.009 Luminosity estimates

  17. Constraints to 2015 • Energy • Splice consolidation 2012++ • Should open the way to 6.5/7 TeV • ~2 years at 6.5 TeV before hitting 7 TeV • Beam intensity limits from collimation phase 1 • 40% maximum – less with imperfections • 2012 + X: modification of DS • 2012 + X + 1: DS collimators buys nominal intensity • 2014/2015: Full phase 2 buys nominal and ultimate intensity • If X > 0 then assume everything done after 2014 run • Until then 40% limit holds – which is not a major disaster Luminosity estimates

  18. Collimationphase 2 NB: limit, not prediction Luminosity estimates

  19. 2015 - 2020? • Arrive at end 2014 (with a bit of luck) • 7 TeV • Around 20% nominal performance • 10 - 20 fb-1 in the bag • On the schedule: • LINAC4 (lose 6 months of proton physics) • DS collimators in – good for nominal • Collimation phase 2 – good for ultimate • Phase 1 upgrade (1 year shutdown plus re-commissioning) Luminosity estimates

  20. 2015 - 2020? • Statistical error halving time • Accumulate X fb-1 per year • A naïve 3 more years at the same rate to halve the error • Flat lining soon becomes uninteresting • However, we’re hardly flat-lining at this stage • Clear that having yet to achieve nominal performance, another major shutdown would not be optimal at this stage Luminosity estimates

  21. Plan A • 2012++ – splice consolidation and DS collimation prep. • 2013 – 6.5 TeV – ~25% nominal • 2014 – 6.5 TeV – ~40% nominal • 2015(?) – LINAC4 (6 months), collimation phase 2: • No phase 1 upgrade • Ions, 2 months recommissioning, 4 month protons • Presumably contingent on delivered integrated luminosity • 2016: 7 TeV – nominal performance • 2017 – 2020 • A) Push to nominal and then flat-line (more-or-less) • B) Push towards ultimate • 2020 – 2022 – possible upgrade • Presumably contingent on delivered integrated luminosity etc. Luminosity estimates

  22. Plan A Luminosity estimates

  23. To 2014 • 2012: splice consolidation (and DS collimator prep (?)) • 2013: 6.5 TeV ~25% nominal intensity • 2014: 6.5 TeV ~40% nominal intensity Luminosity estimates

  24. Independent estimate Courtesy of a rather pessimistic but perhaps more realistic Massi Ferro-Luzzi At least in the same ball park Hubner Factor ~ 0.2 Luminosity estimates

  25. 2015 – 2016 to nominal 2015: Take a 6 month hit for LINAC4 & collimators phase 2, say, Optimist Might hope to hit nominal in 2016 Massi Luminosity estimates

  26. Beyond 2016 • Assumptions • PS at increased injection energy plus LINAC4 are good for ultimate (after a suitable commissioning period) • ~1.7 x 1011 can be swallowed by the SPS • Give or take a long shutdown • LHC can swallow ultimate intensity • “Ultimate intensity is challenging for the LHC. Many systems at technological limits with little or no margin.” (R. Assmann – Cham 2010) Stay at or around nominal Able to push towards ultimate Luminosity estimates

  27. 2010 - 2020 Luminosity estimates

  28. Conclusions • Luminosity estimates for the next ten years presented • Biased towards the optimistic • Nominal performance by 2016 • 21st century Hubner factors • Big errors bars and numbers should be treated with care particularly after 2016 • Important to gain some operational experience!!! Luminosity estimates

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