Yearly beam losses in past and future operation

1. Yearly beam losses in past and future operation Mike Lamont Belen Maria SalvachuaFerrando Very much an invitation to do some more work!

2. Loss Mechanisms Many, many moons ago – attempted to cross product loss mechanisms against the nominal cycle • Transverse • Beam gas • Collisions • Halo productions: • Nonlinearities, long range beam-beam, electron cloud, IBS • Longitudinal • Touschek, RF noise, IBS • Particles can be: • Scattered directly out of aperture • Particle pushed to large betatron or momentum amplitude • lost on physical or dynamic aperture • Emittance growth • slow push to large betatron or momentum amplitudes LHC Annual Doses

3. Nominal cycle I  t I  et I  t2 LHC Annual Doses

4. LHC Annual Doses

5. Nominal cycle – WHEN • Injection • Losses at injection: injection oscillations, RF capture • Big beams, lower dynamic aperture, full buckets, un-captured beam, long range beam-beam, crossing angles, persistent current decay • Won’t be pretty. 10 hours lifetime will be good. • Start ramp • Un-captured beam: lost immediately (~5% total) • Snapback: chromaticity, tunes all over the place • Ramp • Things should calm down, assume 10 hour lifetime • Squeeze • Tunes, chromaticity, collimator, TCDQ adjustments – expect some lifetime dips • Collide • Beam finding, background optimisation • Physics • Collisions, beam-gas, halo production • Synchrotron radiation damping will help against IBS, noise LHC Beam Loss Rates

6. Operational Cycle Some old, rather pessimistic assumptions LHC Annual Doses

7. Physics LHC Annual Doses

8. Lifetime evolution in physics Attempt to combined the various lifetime effects and proportion the losses to their destination Nominal single beam lifetime, fitting to exponential ≈ 37 hours Luminosity lifetime ~ 18 hours LHC Annual Doses

9. Losses before physics LHC Annual Doses

10. Losses in physics beam loss in various locations, per fill for differing fill lengths. Nominal physics – one beam. LHC Annual Doses

11. Old operations assumptions • 200 days physics per year. • 60% operational efficiency • Machine available for beam • Fill lengths • Assume between 8 and 20 hours. • Turnaround • Time between consecutive physics coasts • Absolute minimum turnaround time between physics coasts: ≈ 90 minutes. • Varied between three and ten hours. New operational assumptions – not so much different LHC Beam Loss Rates

12. Totals Per Year NOMINAL ULTIMATE 7 TeV equivalent LHC Beam Loss Rates

13. Analysis: Belen Maria SalvachuaFerrando IN Reality LHC Annual Doses

14. Experience • We know have vast experience of ramping, squeezing, colliding and stable beaming high intensity beams LHC Annual Doses

15. Take a recent fill • 2663 • Peak luminosity: 6.52e33 cm-2s-1 • Stable beams: 11 hours 20 minutes • Beam current: ~2.1e14 • Average bunch intensity: ~1.5e11 LHC Annual Doses

16. Injection - bct Ramp Squeeze LHC Annual Doses

17. Injection – TCP losses B1 Injection – TCP losses B3 LHC Annual Doses

18. Ramp – TCP3 losses B1 Ramp – TCP7 losses B1 Ramp – TCP7 losses B2 LHC Annual Doses

19. Squeeze – TCP7 losses B2 LHC Annual Doses

20. Adjust – TCP7 losses B2 Stable beams – TCP7 losses B2 Stable beams – TCP7 losses B1 LHC Annual Doses

21. Stable beams – QXA losses B1 LHC Annual Doses

22. LHC Annual Doses

23. LHC Annual Doses

24. LHC Annual Doses

25. Total Integral:  180.02 Gy/s Total time during  RAMP   792.0  sec Beam1: Total proton lost  1.15e+12 Beam2: Total proton lost  2.17e+12 Total Integral:  263.8 Gy/s Total time during  SQUEEZE   1038.0  sec Beam1: Total protonlost  0.78e12 Beam2: Total protonlost  2.27e+12 Total Integral:  220.6 Gy/s Total time during  ADJUST   467.0  sec Beam1: Total proton lost  1.07e+12 Beam2: Total proton lost  1.67e+12 Total Integral:  1005849.1 Gy/s Total time during  STABLE   40839.0  sec Beam1: Total protonlost  0.49e+14 Beam2: Total protonlost  0.55e+14 SO Can accurately determine how much IS lost and when… LHC Annual Doses

26. LHC Annual Doses

27. Vast majority in IR7 with some at injection protection LHC Annual Doses

28. IR3 – out of bucket flash at start of ramp • Gentle “scraping” in IR7 at top of ramp as collimators move to tight • Clearly can change if we have problems… LHC Annual Doses

29. IR7! LHC Annual Doses

30. IR7! • Plus start of collisions… LHC Annual Doses

31. debris protons LHC Annual Doses

32. Single beam lifetimes [hours] • Luminosity debris • Transverse emittance blow-up • Longitudinal losses • Minimal beam-gas Fully quantifiable (with a little effort) LHC Annual Doses

33. 2663 loss summary • Relatively straightforward to establish: • When • Where • How much • Mine the past to predict the future… LHC Annual Doses

34. Annual Number of Lost Protons at TCPs andPrediction for 2012 LHC Annual Doses

35. Detailed Look into Losses at TCPs DuringStable Beams in 2011 (BLM vs BCT) LHC Annual Doses

36. 10 year plan LS1 PHYSICS AT 6.5/7 TeV LS2 “ULTIMATE” PHYSICS LS3 HL-LHC NB: not yet approved LHC Annual Doses

37. 2012 – canonical (long) year ~150 days LHC Annual Doses

38. Efficiency 2012 LHC Annual Doses

39. Potential performance LS1 to LS2 • 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! LHC Annual Doses

40. Performance estimate LS2+ • 7 TeV • 150 days of proton physics • Hübner Factor = 0.2 for 25 ns • Different OP model for 50 ns levelled Neglecting low emittance option All numbers approximate! LHC Annual Doses

41. Projection • 25 ns • Low emittance option viable between LS1 & LS2 • Usual warnings apply LHC Annual Doses

42. Conclusions • Old estimates presented • The LHC is a lot cleaner than expected (fortunately!) • Good handle on when, where and how much • Reasonable understanding of the mechanisms • Given past experience of losses and availability should be possible to make realistic predictions for future operations based on appropriate scaling with total beam current and luminosity. LHC Annual Doses