LHC Commissioning Phases

1. LHC Commissioning Phases Commissioning injection and first turn presented by B.Goddard Summary of considerable efforts over past years from whole of the LHC commissioning team Particular acknowledgement for input and feedback to this talk are due to Mike, Roger, Verena, Volker, Jan and Jörg. Thanks also to the “procedures” team for their much-appreciated efforts: Magali, Stefano, Laurette, Reyes, Verena

2. LHC Commissioning Phases: Phase 1 – Injection and first turn • Introduction: LHC Commissioning Stages and phases • Phase A.1: Injection and first turn • Objectives • Preconditions and tools • Equipment state/readiness (exit from machine checkout) • Controls, software and tools • Operational cycles, modes and states • Machine setup • Machine protection • Magnets • Beams • Commissioning procedure • Breakdown • Details of some steps • Possible problems • Outstanding issues • Documentation • Intermediate milestones and beam tests • Summary

3. LHC Commissioning stages

4. LHC Stage A: Commissioning phases Phases for full commissioning Stage A (pilot physics run) Phases for proposed 2007 engineering run

5. Injection and first turn – Basic objectives • Beam through last 100 m of TLs and injected into LHC • First commissioning of key LHC beam instrumentation • BPMs, BLMs, BTVs, FBCTs • Commission trajectory acquisition and correction • Threading – concentrate on getting beam around, leaving systematic measurements for later phase • Corrector / BPM polarity and calibration checks: as needed • Local aperture checks: as needed • Detailed kick/response analysis: if needed • Coarse energy rematching: if needed • First turn completed – ready for next phase (establish circulating beam)

6. Injection and first turn – Objectives

7. Injection and first turn – Objectives

8. Injection and first turn – Equipment state and readiness (entry) • LHC checkout and operations dry run performed • TI 2 and TI 8 beam commissioned down to the last TED. The rest of TI 2 and TI 8 hardware commissioned • Injection interlocking completely tested (last section of transfer lines + other injection BIC entries, beam dependent signals as far as possible) • Main LHC systems all ready for 450 GeV…

9. Injection and first turn – Equipment state and readiness (entry)

10. Injection and first turn – Equipment state and readiness (entry)

11. Injection and first turn – Equipment state and readiness (entry)

12. Injection and first turn – Controls, software and tools • Applications and tools from CO, LSA, OP and equipment groups • Details, priorities and responsibilities defined in High Level Control requirements for the LHC commissioning with beam • Some key elements for the Inject and First Turn phase are: • Whole suite of LSA applications for equipment control • FiDeL for machine cycling and settings • Orthogonal steering at injection point across TL/LHC ‘interface’ • Collimator control for TDI • BPM and BLM acquisition and data concentration • YASP for threading • Sequencer for managing mode changes, timing tables, BIS arming, … • Shot-by-shot logging and archiving • Loco available for orbit response analysis if needed • Online MADX model available if needed • Online aperture model available if needed • Take for granted all generic facilities available (alarms, network, …) M.Lamont LSA pages

13. Injection and first turn – Operational cycles, modes & states • Small subset needed • Pre-cycle • Pre-injection plateau • Injection plateau • Inject pilot • Inject and dump • Occasional re-cycle • Sequencer to drive this M.Lamont, ABCIS 3/2007

14. Injection and first turn – Machine protection • Magnet protection assumed to be fully commissioned • Single pilot bunch poses no damage risk for LHC machine • SPS interlocking to make sure only a pilot is delivered • SPS HW intensity interlock (set and tested to ~41010 p+) • SPS Safe Beam Flag to allow extraction into empty LHC • SPS extraction master BICs with logical conditions tested • LHC BIS will be operational, including injection BIC • Injection permit only if LHC beam permit loop closed • Critical Settings Management MCS system to ensure that configured settings are not corrupted or changed by unauthorised persons • Role base Access RBAC to limit settings access to authorised persons • Beam dump and LHC mode “Inject and Dump” to allow screens to be in

15. Injection and first turn – Machine setup • Start with “pre-squeezed” 11 m b* optics • Benefit for subsequent 450 GeV collisions and 7 TeV commissioning • Keep 17 m b* as fallback • Use ‘nominal’ machine cycle with machine cycled to Imax • Wait ~30 minutes before injection for decay of persistent currents • Prepare & test ‘de-Gauss’ cycle as backup solution • Cycling strategy of all classes of magnets needs to be decided, deployed and tested

16. Injection and first turn – Machine setup • Magnet settings determined by FiDeL online model • Start with best-guess predictions of harmonics, transfer functions and corrections • Families required: • Main lattice circuits (bends, quads) powered to nominal • Use commissioning tunes • Crossing angles at zero, separation bumps at zero. • Correction circuits required • orbit correctors, trim quads, sextupole spool pieces, lattice sextupoles, skew quads • Correction circuits not required (on and demag. cycle to zero field) • Inner triplet multipole compensation • Skew sextupoles, lattice octupoles, octupole and decapole spool pieces. • Circuits which need to be switched OFF (software interlocked?) • Spectrometer magnets and compensators. • Experimental solenoids M.Giovannozzi, Chamonox 2006

17. Injection and first turn – Beams • Beam type: pilot Ib: 5 109 p+ en: 1 – 3.5 mm.mrad (small en possibly for detailed aperture measurement) • LHC mode: “inject and dump” (set 10-1000 turns) a) One ring, single injection on demand b) One ring, repeated injection

18. Injection and first turn – Breakdown (1 beam) • Sequential: first beam 2 then beam 1 (save interleaved for later phase)

19. Injection and first turn – details • Injection preparation: • Check SPS intensity limit (should be 3 to 4 10^10) • Check logging database and SDDS [event triggered and indexed database?] are running. • Check kicker settings (54 kV) and waveform. • Inhibit extraction from SPS • Pulse injection kicker (need LHC beam permit and injection permit) • Verify injection kicker waveform with OASIS (amplitude and synch) • Move all screens in beam (Al203) (minimum IR8 MSI and TDI). Set BTV application to subscription mode. Set Inject and Dump counter to 1000 turns. • Move TCDIs downstream of downstream TED out of beam. • LHC Sequencer changes LHC to mode “Inject and Dump”. LHC master. • LHC Sequencer makes request to CBCM with ring, bucket number, beam type and number of PS batches. • Extract towards last TED in TI 8. • Check dump firing, XPOC result and BIS rearming.

20. Injection and first turn – details • Setup injection elements and beam to TDI without MKI: • Close TDI completely in IR8 (one jaw IN). [Settings in mm or pre-defined?] • Power MKI on, but kick disabled. • Take away extraction kick enable in SPS. • Move out TI 8 TED. • Check all elements pulsing/powered • Extract towards LHC. • Check BLMs and BPMs reading back, and screen TVs on. • Thread beam through the last bit of TI 8 and the MSI; • Beam through MSI into LHC – image on screen at MSI; • Steer roughly through MSI – detailed setup later • Thread through Q5, MKI, Q4, D2 to TDI • Image on BTV at TDI.

21. Injection and first turn – details • Threading: • LEP strategy: correct over small range (manual BPM rejection); iterate • Watch out for separation/recombination dipoles (transfer functions…) • Method has been checked by Jorg, coupling MAD-X to YASP steering program, via aperture filter, noise etc. (LHC beam 1). • Results promising (without big problems, eg quad polarity reversals): 13 iterations for first-turn. • Fairly insensitive to errors, e.g. isolated bad BPMs with >10mm offset • Number of faulty BPMs before intervention to repair? • As needed when get into trouble – as long as beam keeps going round, continue J.Wenninger LTC 2006

22. Injection and first turn – details • Threading (beam 2): • Move TDI out - start threading - D1 as corrector, steer through inner triplet, need BPMs, BLM. • Thread through matching, dispersion suppression. • Thread ARC 7-8: energy offset, correct if needed • Observe beam on screen R7. • Thread ARC 6-7: does the energy match ARC 7-8? Adjust if needed • Iterate through the other arcs and LSS • Commission screens, point 4 BCT on the fly. • Throughout: • Kicks & polarity - first checks as needed. Systematic measurement program if we get stuck anywhere. • Detection of poor BPMs: Look at orbit in normalized coordinates, compare predicted and achieved correction, use experience. • Detection of COD errors: Compare predicted and achieved correction  use few CODs / step, use experience.

23. Injection and first turn – details • First energy mismatch measurement and correction • Inject & measure using YASP • Accuracy of ~0.1% level should come for “free” from the dispersion trajectory • What is correction threshold? 0.2-0.3%? Probably most efficient to leave to later if possible and beam continues to go round • Correct if necessary • Between arcs for one ring → adjust MB currents in LHC • Between SPS and both LHC rings (end of Phase A.1) → change radial position and main bends of SPS and retune TLs (to get average correct) • Between LHC ring 1 and ring 2 → adjust with horizontal orbit correctors (anyway at later stage).

24. Injection and first turn – details • BPM and corrector polarity and calibration checks • Some faulty elements will be found during threading • Results introduced in configuration file ‘online’ in YASP. • Eventually have to fix polarity errors – delay until opportune • Disable faulty/bad BPMs if not needed • Repair only where essential (e.g. if crate down) • Systematic checks can be made as needed during threading with kick-response and Loco analysis (lengthy as ~60 seconds per scan point) • Perform systematic scans using two correctors, to get BPM polarity response, corrector polarity response, rough BPM calibration factor, rough corrector calibration factor • In general, for this analysis the iterative fitting needs experience…

25. Injection and first turn – Possible problems • Cannot thread beam around – beam lost somewhere • Causes: physical aperture (e.g. RF fingers, …), misaligment, wrong transfer functions, wrong magnet settings, polarity errors. • Diagnostic tools: BLMs, mobile BLMs and display, BPM intensity mode, radiation survey piquet, survey data, TF reference data, settings information. • Remedies: Local steering, use smaller en, update TF data, update settings, realignment, element replacement • Issues: Over-activation of components at problem location – cool-down times • BPM errors render threading impossible • Causes: Polarity errors, calibration errors, cable inversions, electronic faults • Diagnostic tools: Analysis of steering data, systematic polarity/calibration scans, configuration data for connectivity • Remedies: Updated configuration, disable affected BPMs, repair. • Cannot close beam permit loop / spurious interlocks • Causes: Client cannot give beam permit on non-maskable input • Diagnostic tools: BIS supervision SW and equipment expert applications • Remedies: Change thresholds in case of remotely configurable levels, repair equipment, disconnect and reconfigure DB and retest affected BIC • Issues: If reconfigured, scope of tests to be remade after problem diagnosed, authorisation mechanism for interlock disabling

26. Injection and first turn – Possible problems • Unstable injection after recycling, cannot reproduce machine • Causes: PC decay effects, FiDeL prediction inaccuracies • Diagnostic tools: trajectory analysis, beam loss measurement • Remedies: De-Gauss cycle, longer waiting times, FiDeL modification, … • Systematic quenches associated with pilot beam loss • Causes: Beam loss quench level lower than predicted, weak magnet, short loss length associated with aperture limit • Diagnostic: magnet test data, beam post-mortem, machine post-mortem, local aperture model • Remedies: Reduce pilot intensity to minimum compatible with BPMs (2109 p+?), increase en to maximum (5–10 p.mm.mrad ?) to reduce deposited energy density, steer around aperture limit • Injection element performance problems • Causes: vacuum leak late in HWC requiring bakeout, MKI HT problems, TDI • Remedies: block TDI out, inject with kicker off using vertical correctors, … • Issues: injection protection for increasing intensity, injecting without MKI only good for first turn, …

27. Injection and first turn – Problems and contingency plans • In case of problems, detailed measurements planned for later in the commissioning programme may need advancing • Aperture scans, systematic polarity checks, … • Relevant software, tools, preparation work and people for these activities should ready for the A.1 phase, even if they are not planned to be used • Extension of the “what if” exercise could be made • Should define problem causes, diagnostics, remedies and issues • Balance (possible) increased extent of readiness with effort spent on preparation for eventualities which may not happen • What is the decision-making process in the event of problems, and are the lines of responsibility clear (e.g. if BIS is reconfigured, or a commissioning step is skipped)?

28. Injection and first turn – Some issues • Display of the spare channels of BLM cards should be available in CCC • Needed for mobile BLMs. • Software for BPMs in intensity mode… • Complicated: beam 1 and beam 2 interchanged, new calibration tables… • PCBs already on critical path…. • Probably difficult to quench a magnet at this stage...but are BLM thresholds remotely changeable or not? • Extent of parallel commissioning possible/desirable? Probably none at this stage – an issue for later phases • Not planning to check interleaved ring 1/ring 2 injections. Are there circumstances under which this could be necessary already in this phase? • If so should already be fully prepared and tested. • What form will the aperture information be available? • Online model derived from layout DB and interfaced to MADX and the steering applications would be ideal….

29. Injection and first turn – Some issues • What are the thresholds for irradiation, e.g. aperture limit during threading • Might affect access possibilities if dump beam for 1 day in same spot • Can we define beforehand for different regions (arc, experiment, LSS, …)? • Recycling • How often is recycling required (e.g. if energy mismatch detected and MBs adjusted)? • Cycling strategy to be fully defined for each circuit. • How does this change when we cycle to below 7 TeV settings? • Will we have an additional event indexed logging database or retrieval functionality?

30. Injection and first turn – Documentation • Target: detailed complete procedures assembled for each phase • Rationalized collection of information from LHCCWG, Chamonix workshops, Mike’s commissioning pages, LHCOP, LTC, LSA analysis, … • Define entry conditions, exit conditions, stepwise procedure, subsystem component, controls and software requirements, known problems, ‘what-ifs’, open issues • Presently web–based, could move now to publication of phases in comprehensive ES - implies approval and maintenance Phase A.1: M.Gruwe LHCCWG 2/2007 Procedures: V.Kain LHCCWG 5/2006

31. Injection and first turn – Intermediate milestones • TT40, TT60, TI 8, TI 2 re-commissioning and commissioning • Pilot and nominal beam to downstream TEDs • Interleaved extraction via sequencer • Software, tools, instrumentation, logging and analysis • Full master BIC and interlocking logic • HWC of final parts for TI 2 and TI 8, plus injections

32. Summary • Phase A.1: exit from hardware commissioning and machine checkout into beam commissioning • In this phase aim for simplicity (where possible): • Sequential commissioning beam 2, beam 1, • Stay with single pilot bunch • No detailed or systematic measurement programme unless forced • Nominal magnetic cycle with minimum set of circuits • Some “what-if” scenarios elaborated • Diagnostic and remedial tools should be prepared, tested and ready for use in case problems force more extensive analysis than planned • Aperture scans, mobile BLMs, BPM intensity mode, kick-response scans, aperture model, MADX model, reconfiguration in steering application, … • Documentation: anything more needed or useful? • Responsibilities and mechanisms in problem situations: for masking interlocks, changing procedures, skipping steps, …?

33. References • Web documentation LHC Commissioning procedures, LSA Software analysis, LHC Commissioning pages, LHC sequencer use-cases and specification, LSA software required for phase A.1 • LHCCWG minutes and relevant presentations: Sector Test Plans for Transfer, Injection and First Turn [Mike Lamont] Beam Instrumentation - BPM, BLM, BCT, Transverse Diagnostics [Rhodri Jones] Commissioning Procedures [Verena Kain] Response Matrix Measurements and Analysis [Jorg Wenninger] 450 GeV Optics – Mechanical Aperture and Momentum Aperture [Stefano Redaelli] 450 GeV Optics: IR Aperture and IR Bumps [Yannis Papaphilippou] Tracking error measurement and correction [Jorg Wenninger] Magnetic Field Reproducibility and Differences Between the Apertures [Luca Bottura] Summary of Parameter Tolerances [Frank Zimmermann] Programmed Dumps – Including Inject and Dump Implementation [Brennan Goddard] The LHC Timing System – Operational Perspective [Mike Lamont] What to do if we Cannot Get in Tolerance [Frank Zimmermann] Documentation and Procedures: Phase A1 [Magali Gruwe] Standard LHC Injection Scenario [Mike Lamont] • LTC, MPWG, InjWG, Chamonix presentations: Threading the LHC [Jorg Wenninger] Injection sequencer requirements [Reyes Alemany] Sector test: Proposed Tests with Beam [Brennan Goddard Electrical circuits required for LHC commissioning [Massimo Giovannozzi] LHC Commissioning: Required Application Software [Mike Lamont]