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Orbit correction at injection (dogle g compensation)

Orbit correction at injection (dogle g compensation). H. Bartosik, Y. Papaphilippou LIU- SPS – Orbit correction review, 16. Jan. 2013. Introduction – SPS injection dogleg. i njected beam (horizontal). Displacement of 3 quads in injection region  ORBIT BUMP

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Orbit correction at injection (dogle g compensation)

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  1. Orbit correction at injection (dogleg compensation) H. Bartosik, Y. Papaphilippou LIU-SPS – Orbit correction review, 16. Jan. 2013

  2. Introduction – SPS injection dogleg injected beam (horizontal) • Displacement of 3 quads in injection region  ORBIT BUMP • Gain of aperture for beam dump (in vertical plane) • Ease of injection (horizontal plane) • Designed for the nominal phase advance of 90° (Q26) • Implication for Q20 optics • Injection dogleg creates non-closure  (large) closed orbit distortion • Different trajectory for (high energy) beam dump  closer to upper limit of TIDV • Potentially higher kick strength of MKP needed due to smaller kick from QDA119 QDF118 machine reference QDA117 QDA119 MKPs

  3. SPS injection dogleg – closed orbit distortion • Dogleg = “closed” bumps in both planes for Q26 by design • Dogleg is not closed for Q20 due to different betas and phase advance • Closed orbit of around 7 mm (horizontal) and about 3 mm (vertical) • Assuming only the displaced quads in LSS1 as error source (=perfect machine) Q26 – no correction Q20 – no correction Q26 – no correction

  4. SPS injection dogleg – closed orbit correction • Can be corrected using existing close-by correctors • No problem at low energy (enough corrector strength) • At 450 GeV after small hardware modifications (example here: 3 correctors in total) • After reconfiguration of coils of MDHD.11832 (special COD), already planned for LS1 • Using MDV.11705 and MDVA.11904 at their maximal strength • Interlocking required if powered during extraction • Further correction by additional CODs or higher strength, if needed (see presentation of Eliana) Q20 – corrected Q20 – no correction During LS1

  5. In practice ... • Orbit at low energy corrected using the most efficient correctors • Not necessarily the ones used for dogleg compensation in ideal lattice • No direct limitation for closed orbit correction due to dogleg (sufficient corrector strength at low energy) similar as in Q26 …

  6. Injection – comparison of trajectory • Proton injection at 26 GeV/c • 4 MKP generators with 48.8kV in Q26 • Less deflection from QDA.11910 in Q20  need 51.0kV in Q20 (at least in theory) Q26 Q20 Nominal injection trajectory Trajectory for increased MKP voltage Trajectory with same MKP voltage as in Q26

  7. In practice ... • Injection with Q20 • PROTONS (4 generators) - no operational limitation, same voltage (48.4kV) as for Q26 • IONS - not managed yet to inject using only 3 generators … further tests needed

  8. Summary and conclusions • Dogleg in LSS1 for gaining aperture for beam dump and ease injection • Dogleg creates large closed orbit distortion in Q20 • Orbit corrected as usual at low energy  no limitation due to dogleg • Correction at high energy possible after coil reconfiguration of MDHD.11832 (during LS1) • Correction at flat top can be tested after LS1 (interlocking required if used at extraction …) • Dogleg not (directly) related to orbit variation at extraction (see talk of Eliana) • Injection and beam dump trajectories are slightly different in Q20 • … since trajectory goes off-axis through quadrupole (even without dogleg!) • No practical limitation for injecting protons (but larger MKP kick needed for Q20 ions) • Higher position on dump block TIDV (to be discussed during beam dump review) • Even removing dogleg would not help for injection and beam dump

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