LHC Performance Workshop Summary Session 5 2016 & Run 2

1. X LHC Performance Workshop Summary Session 5 2016 & Run 2 Paul Collier & Giulia Papotti Chamonix Session 5

2. Session Contents There is a lot of detail in these talks!! Chamonix Session 5

3. YETS Recovery • Feb. 26/27 – DSO Tests • March, 4 – LHC tunnel closed and start of powering tests • March, 16 – end of powering tests, experiments closed and (official) start of machine check-out • March, 21 – start of beam commissioning • It is going to be tight! • 12 Days for Hardware Commissioning • 5 Days Machine Checkout Plans are in place for most systems and services (LBDS, Kickers, Collimators RF, BI, Controls etc.) Challenging series of tests – but should be ok. The big worry is the re-qualification of the cold circuits Chamonix Session 5

4. Powering Tests • UPS Tests systematically in each sector • Overhaul of the 32 Main circuit EE systems • HV tests needed afterwards • Temperature drifts in DFB’s and MS • Need for ELQA on many circuits • Powering tests: • 7000 tests in 12 days!! • 1/3 are 60A … should be ok • Massive parallel testing – rely on automated sign-offs Very Challenging! Will rely on availability of the sectors for powering No access (apart from that needed to power) Chamonix Session 5

5. Experiment Requests and Requirements • As usual a rich diversity of requests! • High Luminosity Proton-proton running at 13 TeV • Special Runs • Heavy ion Running • Lots of 13 TeV p-p data for ATLAS/CMS (~30/fb @ 25 ns): • ~40cm β* (approximately twice the luminosity/pileup of 2015) • LHCb Leveled with b* = 3m to a m of 1.1 • ALICE Leveled with b* = 10m to a m of 0.01 • Both require regular flipping of magnet polarity (new for ALICE) • TOTEM aligned from the start and taking data during high intensity runs. • In addition to high intensity p-p must foresee the following: • One early VdM scan (with possibility of another depending on analysis) • A high β* (~2.5km) running period for TOTEM/ALFA(no 90m β* run in 2016) • 4 week Heavy Ion period, details still under discussion • LHCf do not foresee taking data in 2016 except in a possible 8 TeV p-Pb run • A few Special Requests Chamonix Session 5

6. Miscellaneous p-p • VdM scans early in the year (~2 days) • hopefully the only one … setup as in 2015: • β* ~ 19 m (IP1 & 5), 24m IP8, ε ~ 3 µm, zero crossing angle (large at IP8) and (βx =βy) • Request also a length scale calibration (same optics as VdM) • LHCb may take SMOG data • Other Things (Special Requests): • CMS interested in a high pile up run (few intense bunches) • ATLAS/CMS want some periods of low/medium pile-up using separation levelling • ‘After-glow calibration’ run – 4 widely spaced high intensity bunches • During normal runs: • Experiments support having non-colliding bunches (similar to 2015) as long as these do not cause instabilities • Also request isolated bunches in the filling scheme during ramp-up for ‘out of time’ pile-up studies. Only during occasional fills. • All of these will have some kind of overhead! Chamonix Session 5

7. High Beta* Running • Goal: • Measure elastic proton-proton scattering in the Coulomb-nuclear interference region and potentially measure the luminosity independent of VdM scan. • Beam Settings: • β* as high as possible (β*> 2 km) • Zero crossing-angle • 3 bunches (2 colliding in 1&5) • As low emittance as possible • Vertical Roman Pots positioned at 3 σnominal or closer • Scheduling: • Optics commissioned before – extra time added to MD periods for this • 1 day final set-up and 3 days Physics probably in September. Important to minimize the impact on the High-Luminosity running Chamonix Session 5

8. Requests for Heavy Ion Running • Significantly different requests from the experiments • Still under discussion, Hopefully converge on strategy before the March LHCC • The current options under discussion are: It would be useful to know so we can prepare! Experiments would also like a 5 TeV p-p reference run. But Differences in opinion as to whether this should be included in the Heavy Ion periods • Long term plan for HI running desirable Chamonix Session 5

9. Ion Run (from the Machine Side) The experiments have not made their mind up yet … have to plan for all options • A Pb-Pb run in 2016 would be very similar to 2015 • Possibly lower b* but in any case dominated by burn-off • P-Pb is actually slightly easier at higher energy • Smaller frequency difference – orbits less offset. • Can run with the p-p b* for ATLAS and CMS • But ALICE will be limited to higherb* by the 2mm vertical offset and anyway levelled Within the usual 10-15% uncertainty In all cases Luminosity sharing is going to be a difficult subject Chamonix Session 5

10. Beams from the Injectors Injectors running close to the limit(s) – Hence LIU!! • Increasing longitudinal emittance and bunch length will put the PS space charge limit in the shadow of the PSB space charge limit Same intensity limit (SPS) with slightly smaller transverse emittance might be possible, hence brighter beams Chamonix Session 5

11. Beam Status = Available = Ongoing / Considered • Still new ideas coming! (80 bunch scheme) • A well scrubbed SPS will be vital to reach top performance • Little room for other improvements until LIU • Availability is the only way to significantly improve overall performance Chamonix Session 5

12. Machine Development • Short Term – of immediate benefit to the performance • As much as possible try to move these into commissioning/operation periods • Medium – development for the future running for run2 & run3 • Development of future running scenarios • Long – Necessary MD’s for HL-LHC • ‘Long’ is a misnomer. Some of these need answers in the relatively short term, eg to make decisions on the baseline • Very Long – Future machines, basic understanding • For example, studies for FCC • This is not a prioritisation • Data from MD’s of all types is needed to make progress • Balance between long term performance and shorter term gains • MD’s also allow us to develop our basic understanding of accelerator physics • The time spent doing MD’s invariably pays off Chamonix Session 5

13. MD scheduling • 2016: 22 days Scheduled >30 days requested already! • 2017: Shorter year, 15 days scheduled • 2018: Hopefully 22 days again • A Few Priorities (for the LHC) in 2016: • ATS Optics for pushed b* and flat beam studies, • Online coupling correction and IR non-linear corrections, • Collective effects: E-Cloud, beam-beam etc. , • Collimation: Impedance, Quench limits, Halo control, Crystals, • Emittance Growth, • System Development: RF, LBDS, Injection, Beam Instrumentation, Machine Protection, Chamonix Session 5

14. Machine Configuration for 2016 • 2015 was a commissioning year ... relaxed b* • emphasis on getting LHC running with 25ns beams at 6.5 TeV • 2016 is a production year – push performance … lower b* • Complete intensity ramp up with standard 25ns beams • But we should not jeopardize availability! For 2016 Choice of b* and associated crossing angle and collimator settings 10 s BB sep 11 s BB sep • Need: • Tighter Hierarchy in IR7/6 • 10 s beam-beam separation • Optics with re-matched phase • Recover the aperture margin established last year • All depends on the measured aperture being as good as before Chamonix Session 5

15. Performance Reach • At lower b* the Geometric reduction factor becomes increasingly important • Can reduce the bunch length to limit the effect … to be tested! • Initially start with standard 1.3 ns – look to reduce later • The choice seems to be between b* = 40 and 50 cm ``` Relative Integrated Luminosity • 40cm gives slightly more Ldt, but: • Everything is tighter … • will it affect availability? Shorter fills? • On the other hand it did work in tests last year! • Best Plan: • Assume we go for 40cm • Measure aperture for final choice to start with, • Start intensity ramp up, • Be ready to step back if we run into problems (some overhead here) 8h fill length 20h fill length With both 50 and 40 cm it should be possible to reach >1x10+34 Chamonix Session 5

16. P-P Plans for 2016 • What do we Want: • Stable Safe Operations • Don’t compromise on machine safety! • Don’t do anything to compromise machine reproducibility • Electron Cloud under control • Short dedicated scrubbing • Continue during intensity ramp-up • 6.5 TeV, 40-50 cm b* • Keep an eye on availability • Nominal 25ns beam, 2748 bunches, 288 bpi • May push later to shorter bunches & BCMS • Reasonable Good! Availability • Sustained effort to trace faults • Keep avoidable interruptions to production running to a minimum • Excellent Operational Efficiency • Combined ramp/squeeze • Work on injection process • Don’t Forget: • Check out ULO • Keep an eye on UFO’s – adjust BLM’s? • Commission additional interlocks • Special run set-up (VdM & Hi-b*) • Beware of Earth Faults! Chamonix Session 5

17. 2016 Schedule v1.1 With the present schedule and machine availability we actually spend ~50 days/year in High Intensity p-p stable beams Can we run Longer? Seems unlikely – Availability is the key to more! Chamonix Session 5

18. 2016 Performance Reach Somewhat optimistic assumptions based on availability at the end of 2015 and no new issues from lower b* So,Usual caveats apply: • Availability? Aperture? Interlocks? Phase advance? • ULO, E-Cloud, UFO’s etc. etc. Assume Nbunch = 2736, 3.5 mm emittance, 1.2z10+11 ppb, 1.25 ns Reasonable to assume ~25 fb-1 delivered Chamonix Session 5

19. Run 2 (and Conclusions) • 2017 & 2018 slightly longer for p-p operation (+10 days) • Deliver 100+ fb-1 to ATLAS/CMS … keep ALICE, LHCb, TOTEM & ALFA happy • Keep pushing performance and availability • Peak Luminosity limited to ~1.7x10+34 by Inner Triplet cooling • Look forward to HL-LHC without compromising present performance • ATS, b* levelling, LRBB compensation tests, full RF detuning • Prepare for 7 TeV operation • Training campaign in (some) sectors during EYETS? Enthusiasm and commitment remains high – we could do some serious stuff in 2017 & 2018 M. Lamont • EYETS – Extended Year End Technical Stop – 19 weeks – CMS pixel upgrade • Assume machine stays cold during EYETS • Assume for the moment: p-Pb end 2016, Pb-Pbend 2018 – tbc. Chamonix Session 5