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MTE status and outlook for 2012

Introduction Recap of 2011 activities Activities before LS1 Milestones

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MTE status and outlook for 2012

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  1. Introduction • Recap of 2011 activities • Activities before LS1 • Milestones Acknowledgements: G. Arduini, H. Bartosik, J. Borburgh, R. Brown, M. Buzio, S. Damjanovic, S. Gilardoni, C. Hernalsteens, M. Hourican, A. Lachaize, Y. Papaphilippou, R. Steerenberg, and many colleagues in BI, OP, RF, DGS-RP, and TE-ABT, TE-MSC… MTE status and outlook for 2012 M. Giovannozzi MG - IEFC Workshop 2012

  2. Introduction - I • The three fronts that are being investigated • Activation of septum 16 • Generated by longitudinal bunch structure • Impact on cool down time for intervention in septum area • Fluctuation of trapping efficiency in the PS • Long campaign of beam measurements to find source (not yet identified) • Huge amount of beam data analysed. • Injection trajectories fluctuations in SPS MG - IEFC Workshop 2012

  3. Introduction - II • Mitigation measures proposed • Activation of septum 16 • Dummy septum in SS15 • Hybrid MTE extraction (re-using electrostatic septum for CT) • Fluctuation of trapping efficiency in the PS • Injection trajectories fluctuations in SPS • Different strategy for beam measurements in 2011. • Possibly same source for both issues (magnetic reproducibility of PS main field). Original proposal by Brennan MG - IEFC Workshop 2012

  4. Current layout of SS15 Dummy septum solution • Items under study • Extraction trajectories (TOF should be optimised) and tested with beam. • Relocation of elements currently in SS15 is completed. Additional elements installed during last TS: • Additional DHZ in SS03 • Additional gamma-jump quadrupole in SS99. Everything is ready for beam tests. • Hardware design • Optimisation and finalisation of the design. • Activation and energy deposition studies (including particle tracking). • Shielding optimisation. • Impedance. • Simulation of setting-up with beam. MG - IEFC Workshop 2012

  5. Dummy septum: beam studies - I • To make transverse space for the blade of the dummy septum in SS15 • Move outwards the MTE beam (light blue) • Move inwards the TOF beam (green) Modified fast bump Isl. Slow bump Nominal TOF MG - IEFC Workshop 2012 Courtesy C. Hernalsteens

  6. Dummy septum: beam studies - II • Strategy to reduce amplitude at SS15 • Reduce slow bump in SS15 • Optimise strength of extraction kicker KFA71 • It turned out that KFA4 (used for MTE – extraction of fifth turn) was useful in gaining transverse space in SS15 while reducing amplitude in SS09 (where losses were observed with protons). Without KFA4 SS09 With KFA4 With KFA4 SS15 Without KFA4 MG - IEFC Workshop 2012 Courtesy C. Hernalsteens Courtesy C. Hernalsteens

  7. Dummy septum: beam studies - IV • Main results: • Space gained ≈ 7 mm • Measurements to be repeated with protons to increase statistics and check losses Modified fast bump for MTE Dummy septum Improved TOF MG - IEFC Workshop 2012 Courtesy C. Hernalsteens

  8. Dummy septum: hardware design - I Downstream side Courtesy M. Hourican Blade material: copper or tungsten. Comparable performance in terms of absorption. Choice: mechanical or impedance. MG - IEFC Workshop 2012

  9. Dummy septum: hardware design - II Shielding material: concrete and marble. Shielding dimensions: to be optimised. MG - IEFC Workshop 2012 Courtesy M. Hourican

  10. Dummy septum: energy deposition - I MMU15 SS15 • 1D projection along the blade length, averaged over ±1σx in x and over the blade thickness (3mm). • Maximum value Emax = (21.0±0.1) J/cm3/s E [GeV/cm3/s] Courtesy S. Damjanovic E [GeV/cm3/s] MG - IEFC Workshop 2012

  11. Dummy septum: energy deposition - II Rate for beam loss intensity of 1011 p/s vacuum chambers and beam screen Emax = (1.15±0.005)×10-3GeV/cm3/primary Courtesy S. Damjanovic MG - IEFC Workshop 2012

  12. Extraction with SEH31: recap of CT • Two slow bumps (SS16, SS31) • One fast bump (pedestal and staircase, between SS21 and SS9) • QKE (in SS5/25 and SS25/73) • Two septa (SMH16, SEH31) • Two kickers in TT2 to correct the turn-by-turn trajectory differences MG - IEFC Workshop 2012

  13. Hybrid MTE - I • Phase of KFA13 is not suitable for a closed bump between 21 and 13. • Kicker in 9 will always work at high strength, with KFA13 providing a small correction. • QKEs are needed to “help” the kicker in 9 and provide extra kick to the beam deflected by SEH31. • All this forces to go towards a nearly “carbon copy” of the CT optics. • Guidelines for new solution: • Minimise the strength of QKEs • Close the combined SS16+SS31 slow bump • Close the fast bump MG - IEFC Workshop 2012

  14. Hybrid MTE - II • Tests performed: • Slow bump: combine bumps in SS16 and SS31 Original bump 31: not closed due to magnets in series New bump perfectly closed (also from measurements) MG - IEFC Workshop 2012 Courtesy C. Hernalsteens

  15. Hybrid MTE - III • Tests performed: • Tune control during rise of slow bump and QKEs Huge tune variation. Difficult to measure (too fast for standard tools). Partial correction using F8L. Potential issues: Tune change in vertical plane. Correct response of the circuit. MG - IEFC Workshop 2012

  16. Hybrid MTE - III No tune correction • Tests performed: • Kicked beam into island • Fast tune change induces fast islands’ movement. The beam kicked inside does not follow and filaments Best tune correction Accurate measurement (special analysis tool) and correction of fast tune change are the top priority for 2012 tests. MG - IEFC Workshop 2012

  17. Fluctuations - I • Different strategy to measure PS reproducibility. • Instead of measuring trapping fluctuations, the position of the islands is measured: • Orbit system can be used • Accurate measurement, easier to interpret, and it provides similar information on reproducibility. • Measurement of tune vs. Dp/p MG - IEFC Workshop 2012

  18. Tune vsDp/p Courtesy A. Lachaize • Small but systematic tune difference as a function of preceding magnetic cycle. • Curve shape is also different. MG - IEFC Workshop 2012

  19. Islands’ stability Programmed tune ramp Huge dependence of island’s position on preceding magnetic cycle • Tests with special supercycles • 13 BPs with 1 MTE (and ZEROs) • 13 BPs with 2 consecutive MTE (and ZEROs ) • 26 BPs with 2 MTE (and ZEROs). This case is equivalent to two supercycles of type 1. • 26 BPs with 13 MTE Huge spread for the same preceding cycle Flat-top Reduced variation of island’s position MG - IEFC Workshop 2012 Courtesy A. Lachaize

  20. Statistics over five days - I Courtesy A. Lachaize • Test reproducibility over long period • Test with fixed preceding magnetic cycle • Different ways to change the tune Huge tune variation requiring constant correction! In red measurement’s slots Injectors schedule MG - IEFC Workshop 2012

  21. Statistics over five days - II • October 25th (before injectors’ MD) LHC as preceding cycle seems to improve stability. MG - IEFC Workshop 2012

  22. Statistics over five days - III • October 28th (after injectors’ MD) LHC as preceding cycle does not seems to improve stability. Stability seems already better than before MD. MG - IEFC Workshop 2012

  23. Highlights of Mini-Workshop on PS Main Magnet Field Issues - I • Observations from the OP side – O. Hans • Observations from the MTE side – A. Lachaize • B-field regulation and PFW current regulation – F. Boattini • PS main magnet model and simulations – M. Juchno • Past and recent main magnet measurements and B-train – M. Buzio • Discussion to draw up an action plan MG - IEFC Workshop 2012

  24. Highlights of Mini-Workshop on PS Main Magnet Field Issues - II • Highlights from the mini-Workshop: • Magnetic model is mature for predictive use. • Magnetic measurements (dipole and quadrupole components) are provide interesting data! I*2(t) (quadrupole) Courtesy M. Buzio 2010 measurement campaign by B. Vandorpe quadrupole relative field error  510-3   100ms B = 12650 G Qualitative agreement! No decay of dipole component Sizeable decay of quadrupolar component I(t) (zoom-in) I*1(t) (dipole) MG - IEFC Workshop 2012

  25. Highlights of Mini-Workshop on PS Main Magnet Field Issues - III • Wrap-up session last Tuesday to define actions. • Points relevant for MTE activities: • System for measuring dipole and quadrupole components will be available for measurements in two weeks. • Higher-order (up to decapole) components could be measured in a month. • Possible strategies for improving reproducibility (not necessarily operational…): • Use n (1<n<6) 26 GeV/c before the MTE cycle. • Pre-cycle the main magnets at low current (up-down between 0 A and 50 A) with several mini-cycles (should be fast). MG - IEFC Workshop 2012

  26. Milestones - I • Complete by mid-2012 studies for dummy septum: • Paper studies: • Assessing principle • Finalise the hardware design • Beam studies: • Set up new slow bump (no DHZ15) and new extraction trajectory for TOF beam -> parallel MD • Test new gamma-jump scheme (needs high-intensity beams operational) -> dedicated MD • Perform by mid-2012 tests with new magnetic measurement system (together with beam measurements): • Reproducibility of quadrupolar component for operational and special super-cycles. • Effect of measures for magnetic reproducibility. Parallel MD MG - IEFC Workshop 2012

  27. Milestones - II • Depending on the success of the mitigation measures (to be completed by end-2012): • Resume trapping to confirm improved reproducibility -> parallel MD • Transfer to SPS to confirm improved reproducibility -> parallel MD • Complete by end-2012 studies for hybrid MTE: • Paper studies: • Assessing principle • Beam studies: • Improve tools for tune correction during extraction. • Tests of jumping the electrostatic septum (with CT settings) -> parallel MD • Additional tests with special settings of CT elements -> dedicated MD MG - IEFC Workshop 2012

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