1. (n)QPS LHC status LHC: past, present and future Mike Lamont for the LHC team 1 21-3-2011

2. Clear priority to lay the foundations for 2011 and the delivery of 1 fb -1. Peak luminosity target 1x10 32 cm -2 s -1 Gain solid operational experience of injecting, ramping, squeezing and establishing stable beams Steady running at or around 1 MJ for an extended period Perform a safe, phased increase in intensity with validation and a running period at each step 2010 – main aims LHC status 2 21-3-2011

3. Luminosity: 3 running periods 3 Bunch trains Nominal bunch commissioning Initial luminosity run Nominal bunch operation (up to 48) Performance ramp-up (368 bunches) Performance ramp-up made possible by a safe, staged commissioning. Meticulous preparation for unsafe beams! 21-3-2011 LHC status

4. 2010 parameters LHC status 2010Nominal Energy [TeV]3.57 beta* [m]3.5, 3.5, 3.5, 3.5 m0.55, 10, 0.55, 10 Emittance [microns]2.0 – 3.5 start of fill3.75 Transverse beam size at IP [microns] around 6016.7 Bunch current1.2e111.15e11 Number of bunches 368 348 collisions/IP 2808 Stored energy [MJ]28360 Peak luminosity [cm -2 s -1 ] 2e321e34 4 21-3-2011

5. Overall LHC efficiency in 2010 5 W. Venturini 65% availability! Great achievement for the first year of operation! 21-3-2011 LHC status

6. Physics operations ~30% Stable beams! W. Venturini 21-3-2011 LHC status 6

7. 2010 - records Peak stable luminosity delivered2.07 x 10 32 cm -2 s -1 Maximum luminosity delivered in one fill6.3 pb -1 Maximum luminosity delivered in one day5.98 pb -1 Maximum luminosity delivered in 7 days24.6 pb -1 Maximum colliding bunches348 Maximum average events per bunch crossing3.78 Longest time in Stable Beams for one fill30.3 hours Longest time in Stable Beams for one day22.8 hours (94.9%) Longest time in Stable Beams for 7 days69.9 hours (41.6%) Fastest turnaround to Stable Beams3.66 hours (protons) Courtesy Atlas LHC status 7 21-3-2011

8. Status LHC Stored Energy 80 kg TNT Stored energy reached at 3.5 TeV: 28.0 MJ 8 LHC status Ralph Assmann 21-3-2011

9. Ions LHC status Protons again 50 & 75 ns 9 21-3-2011

10. Excellent single beam before collisions ~200 - 300 hours Luminosity lifetime ~15 - 20 hours  Reasonably well given by emittance growth and intensity decay  Minimal drifts in overlap – beams very stable Intensity lifetime ~90 hours  Luminosity burn, losses on collimators Emittance growth (hor. ~ 30 hours, vert. ~ 20 to 40 hours)  Intra Beam Scattering  and something else – at least sometimes “the hump” Lifetimes 10 21-3-2011 LHC status

11. Aperture LHC status 11 21-3-2011

12. Optics & magnetic machine Optics stunningly stable Machine magnetically and optically well understood  Excellent agreement with model and machine Magnetically reproducible  Important because set-up remains valid from fill to fill LHC status 12 21-3-2011

13. Measured Cleaning at 3.5 TeV IR8 IR1 IR2 IR5 Momentum Cleaning Dump Protection Col. (beam1, vertical beam loss, intermediate settings) LHC status Making sure the hierarchy is respected 13 21-3-2011

14. Excellent single beam lifetime Ramp & squeeze essentially without loss  No quenches with beam above 450 GeV  Excellent performance of Machine Protection Optics close to model (and correctable) Excellent reproducibility Aperture as expected Better than nominal from injectors  Emittances, bunch intensity Beam-beam: can collide nominal bunch currents  With smaller that nominal emittances LHC 2010 - summary 14 And surprisingly good availability… 21-3-2011 LHC status

15. PROBLEMS – TWO OF THEM LHC status 15 21-3-2011

16. Many sudden local losses have been recorded. No quench, but preventive dumps Rise time around of the order 1 ms. Potential explanation: dust particles falling into beam creating scatter losses and showers propagating downstream Distributed around the ring – arcs, inner triplets, IRs UFOs – unidentified falling objects LHC status 16 21-3-2011

17. ● Revision of thresholds on superconducting magnets could make the UFO effects acceptable ● More detailed analysis needed to understand discrepancies with current simulations + additional quench tests to benchmark UFOs – a possible solution? ● More events at higher intensities ● Only 1? event observed at 450GeV ● Signal shortens, i.e. the losses are faster with intensity ● Signal amplitude does not increase with intensity B.Dehning, E. Holzer, A.Nordt, M.Sapinski 21-3-2011 LHC status 17

18. Electron cloud LHC status Schematic of electron cloud build up in LHC arc beam pipe due to photoemission and secondary emission [F. Ruggiero] Reflection Secondary emission yield [SEY] 18 Very much dependent on bunch spacing: -150 ns. – local signs in common beam pipe -75 ns. – some first signs -50 ns. – vacuum valves in 21-3-2011

19. Vacuum pressure rise (background in experiments) Single-bunch instability Multi-bunch instability Incoherent emittance growth Heat load in cold arcs (quenches in the limit) Perturbation of beam diagnostics Electron cloud effects LHC status Electron cloud effects occur both in the warm and cold regions. 19 Well understood, very well studied (other machines, simulations…) 21-3-2011

20. Vacuum activity started off in regions with common beam pipe at 450 GeV as we pushed up the number of bunches with 150 ns spacing  Test solenoids cured problem – electron cloud Tried 50 ns bunch spacing  Things really kicked off  High vacuum activity in warm regions (single beam pipe)  Significant heat load in cold regions  Instabilities and beam size growth observed  Surface conditioning (‘scrubbing’) observed Gas desorption rates and SEY drop Time constant < 1 day Situation a lot cleaner with 75 ns  incoherent effects seen – emittance blow-up  800+ bunches injected into both beams Experience in 2010 LHC status 20 21-3-2011

21. 2010 observations are certainly due to ~ 2 < SEY < 2.5, whereas 1.7 was usually the max value studied in the past Expect to be able to reach 200-300 b with 75 ns without scrubbing Scrubbing with large emittance (>3.5 mm), high intensity (>1.2e11), 4x36b of 50 ns beam Time  2-3 days needed to setup 50 ns at injection  7 days of scrubbing  1 day for validation and scrubbing result evaluation Lots of wire wrapped around warm bits during the technical stop (solenoids) Scrubbing strategy for 2011 21 LHC status 21-3-2011

22. Solenoids between DFBX and D1 in IR1R LHC status 22 21-3-2011

23. 2011 LHC status 23 Energy – stick at 3.5 TeV – we still worry about the splices 21-3-2011

24. Motivation is clear! 1 fb -1 delivered to each of IP1, IP5 and IP8 at 3.5 TeV  Can probably do better for IP1 and IP5 It will be a challenge to deliver 1 fb -1 to IP8  Maximum luminosity : from 2e32 to 3e32 cm -2 s -1  Luminosity leveling via separation required to get close Alice  pp run: 5e29 < L < 5e30 cm -2 s -1, µ < 0.05 2011: main goals 24 21-3-2011 LHC status fast, secure and far-reaching Decided on beta* = 1.5 m in Atlas, CMS; 3 m in LHCb; 10 m in Alice

25. Beam commissioning: 3 weeks  Exit - stable beams with low number of bunches Ramp-up to ~200 bunches (75 ns): 2 weeks  Multi-bunch injection commissioning continued  Stable beams Technical Stop: 4+1 days Scrubbing run: 10 days including 50 ns injection comm. [Intermediate energy run – 5 days] Resume 75 ns operation and increase no. bunches: 3 weeks  300 – 400 – 600 – 800 – 930 - MPS and OP qualification Physics operation 75 ns: ~930 bunches (50 ns. remains an option if things look good) Baseline scenario 25 21-3-2011 LHC status

26. 2011 LHC schedule Q1/Q2 26 LHC status 21-3-2011

27. 2011 Q3/Q4 LHC status 27 21-3-2011

28. Estimated Peak and Integrated Luminosity LHC status 28 21-3-2011 Energy 3.5 TeV Beta* 1.5 m Bunch spacing 75 ns Bunch intensity 1.2 x 10 11 Stored beam energy 75 MJ Days at peak luminosity 135 Hübner factor 0.2 Emittance [mm.mrad] Beam-beam parameter Peak Luminosity [cm -2 s -1 ] Integrated Luminosity [fb -1 ] 2.50.0061.3 x 10 33 ~2.7 2.00.0071.6 x 10 33 ~3.3

29. 2011 – progress so far LHC status 29 19 th FebruaryFirst beam, circulating beams established. 3 rd MarchFirst collisions at 3.5 TeV, beta*=1.5 m. with pilot beams 5 th MarchNominal bunches at 3.5 TeV, start collimator set-up, injection and beam dump set-up & validation 13 th MarchFirst stable beams, 3 bunches per beam, initial luminosity 1.6e30 cm-2s-1 18 th March32 bunches per beam, initial luminosity ~3e31 cm -2 s -1 19 th March64 bunches per beam, initial luminosity ~6e31 cm -2 s -1 20 th March75ns_136b+4small_138_102_105_24bpi11inj 1.45e32 cm -2 s -1 Impressive re-commissioning, improvements across the board. Operation cycle now well optimized: faster ramp & squeeze, much fewer manual actions required by shift crews 21-3-2011

30. LHC status 30 21-3-2011

31. Machine still beautiful LHC status 31 21-3-2011

32. Injection, ramp and squeeze fully operational LHC magnetic model & optics excellent Beam instrumentation in good shape. Beam cleaning and collimation works reliably with predicted efficiency. Machine protection excellent performance Machine aperture looks good Performance with beam (losses, lifetimes, luminosity, emittance growth etc.) is very encouraging Conclusions 1/2 LHC status 32 We have a beautiful machine on our hands! 21-3-2011

33. Machine availability is excellent – the hard work of numerous teams There are problems  UFOs somewhat worrying  Electron cloud well understood – measures prepared 2011 – another long year ahead…  75 ns. bunch spacing – up to 930 bunches  Nominal intensities, beta* 1.5 m in Atlas and CMS  Should be good for 5 to 10 x 10 32 cm -2 s -1 and 1 to 3 fb -1  Progress so far is good… Will run in 2012  Attempt to measure splice resistance in 2011/2012 might open the way to 4 TeV or higher Conclusions 2/2 LHC status 33 21-3-2011

34. LHC status 34 21-3-2011