Hysteresis Compensation

Parallel MD 2025-10-28

3 min read

Parallel MD 2025-10-28

MD request MD17524 2025-10-28 14:00 - 20:00

SPS user: MD_SHiP_L1230_East_Extraction_2025_V2 PS user: MD15503_MTE_BB_25_Clone_OPsettings PSB user: MD15503_MTE_2025_Clone

MD Goals

  • Measure tune shifts to map , with and without dipole MD1
    • Tune settings to work SFT injection without MD1, reuse for dedicated MD
  • Measure tunes with/without MD1 sextupole precycle (if change, measure Chroma change)
    • Eddy current decay?
  • Repeat for Octupoles

MD Prep

Checklist

  • Using SFT SHiP V2
  • Preceeding MD cycle is flatteable MD1
  • Ensure PSB Cycles are mapped
  • Injected intensity 1e12

Settings to change

  • SPSBEAM/Qh/Qv
  • Transverse dampers
  • Momentum
  • SPSBEAM/B

Apps to use

  • SPS AutoQ

MD

Tune shifts without MD1 (3h)

  • Take reference with MD1

Without dipole MD1

  • Load tag from last MD Parallel MD 2025-08-22
  • Ensure no too big losses
  • Flatten MD1 quadrupole
  • Flatten tune ramp for flat tune
  • Measure tune (10 shots)

With dipole MD1

  • Put back dipole MD1
  • Set up tune
  • Measure tune (10 shots)

Tune spread without MD1 sextupole (1h)

  • With MD1 dipole and quadrupoles flattened

  • Measure chromaticity in both plans

    • Should stay the same

  • Octupoles are only used by SFT → should be fine!

Can be b3 component from imperfections, but unclear

https://indico.cern.ch/event/1101643/contributions/4635257/attachments/2372240/4058445/JAI_course_Jan_2022_handouts.pdf

MD Log

SHiP: MD2 Flat MD1: MD3

Baseline measurement

14:55 Michu enable V damper to reduce coupling in V We make a few supersets and correct tune to 26.58 / 26.62

Baseline measurement with QH=26.5087 , QV=26.544

Improve tune with slightly curved QH line, move tune to 26.62, completely straight tune

Baseline measurement starting 15:10:00, 20 shots Finish 15:20:00 1 lost shot around 15:12

5 min beam stop 15:22.

Very poor transmission because of lack of damper in V Start acquisition 15:28:30. Finish 15:38:00.

15:38:00 set dump to 50 ms 15:41 flaten MD1 quadrupoles, both at the same time

Increase QV by 3e-2 in steps to 26.60 Beam passes, QV=26.52 ()

Beam stop 16:05 - 16:30.

We still lose the beam, but adding 0.2 to QPV seems to stabilize the beam to 100 ms, but still seem to be too close to 26.50 resonance.

Increase tune working point for stability

Increase QH to 26.70, QV to 26.62 (26.59/26.584 resp.) with MD1, so we can stay above 26.50 for QV after MD1 is flattened. Total increase to QPV +0.1 (reverted previous +0.2) to reduce chroma.

Flatten quads 17:29:20. Add back IREF ramp on MBI and tune is completely straight.

Start measurement for QH without MD1 at 17:50:50. Finish at 18:00:50. Reduce V damper, increase H. Start QV measurement without MD1 at 18:02:30 with chirp. Finish at 18:12:30.

Put back quadrupole MD1 at 18:15:16. Decreased QPH by 0.2 to get more stable beam. seems that the added back momentum ramp and no tune ramp caused mismatch, as adding back the tune ramp in H and V fixed it.

Start QH with MD1 at 18:40:10. No Chirp. Finish 18:50:00. Start QV with MD1 at 18:50:20. No Chirp. Finish 19:00:00.

Sextupole check on MD1, but only screenshots.

MD results

  • Get out BPMs (show flat orbit)
  • Plot tunes (H and V separately)
  • Plot programmed QH/QV
  • Plot measured QH/QV IREF
  • Put the number into xsuite and run the conversion into gradient

Graph View