Phase ST2: TDI out: Threading around the ring [beam 1, single pilot]                    

  1. First injections into ring with TDI out

    1. Beam off, move out TDI

    2. Beam on, first injection into ring past TDI (D1)

  2. Coarse beam commissioning of BPMs (asynch. acquisition) and BLMs

    1. Check asynchronous acquisition working for first BPMs

    2. Check readback of BLMs, hopefully signals where beam is lost

  3. Commission trajectory acquisition and correction
    1. Readback of operational BPMs via YASP
    2. First steering in injection region
    3. Rough response checks for first correctors
    4. Test acquisition chain to shot-by-shot logging DB
  4. Threading around ring
    1. Use LEP strategy: correct over small range (manual BPM rejection) using few correctors
    2. Steer through inner triplet, need BPMs (S and D), BLMs to be commissioned in the process
    3. Thread through matching, dispersion suppression
    4. Thread ARC 2-3
      • energy offset, correct if needed
    5. Observe beam on screen L3
    6. Throughout:
      • Repair faulty BPMs only when into trouble – as long as beam keeps going round, continue
      • 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 per step
        • Use experience
      • Avoid changing superconducting D1/D2 if possible at this stage (transfer function knowledge, recycling, ...)
    7. Method has been checked by J. Wenninger , expect few 10s of iterations for first-turn
  5. First measurement of energy mismatch (correction if needed)
    1. Inject & measure using YASP
      • Accuracy of ~0.1% level should come for “free” from the dispersion trajectory
    2. What is correction threshold? 0.2-0.3%?
      • Probably most efficient to leave to later if possible and beam continues to go round
    3. Correct only if necessary
      • Between arcs for one ring : adjust MB currents in LHC
      • Between SPS and both LHC rings : change SPS/LHC frequency and main bends of SPS and retune TLs (to get average correct)
      • First BPM and corrector polarity checks and repairs
        1. 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)
        2. 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
          • 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…
  6. Commission BPM intensity measurement mode
  7. Optional: Systematic BPM and corrector polarity checks and repairs
  8. Optional: Systematic physical aperture scans, free oscillations and sliding π bumps
  9. Optional: Systematic linear optics checks with kick/response
  10. Optional: Momentum aperture measurement