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Triplet corrector layout

Triplet corrector layout. Massimo Giovannozzi – CERN Acknowledgements: R . De Maria, S. Fartoukh. Outline. Introduction New layout of correctors Impact of non-linear correctors on dynamic aperture Strength specification of correctors Summary and outlook. Outline. Introduction

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Triplet corrector layout

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  1. Triplet corrector layout Massimo Giovannozzi – CERN Acknowledgements: R. De Maria, S. Fartoukh

  2. Outline Introduction New layout of correctors Impact of non-linear correctors on dynamic aperture Strength specification of correctors Summary and outlook

  3. Outline Introduction New layout of correctors Impact of non-linear correctors on dynamic aperture Strength specification of correctors Summary and outlook

  4. Introduction - I • Situation in nominal LHC: • Non-linear corrector package provides compensation for non-linear errors in the IR (triplets, D1, D2). • Location of the correctors changed between V6.4 and V6.5 to provide more favourable optical conditions.

  5. Introduction - II • Overview of the strength situation for the nominal machine • Overview of the optical conditions

  6. Introduction - III • Strategy to set the correctors’ strength (see S. Fartoukh, LHC Project Note 349): minimisation of driving terms. • Selection of the driving terms to be corrected: • b3: c(b3; 1, 2) and c(b3; 2, 1) • a3: c(a3; 0, 3) and c(a3; 3, 0) • b4: c(b4; 4, 0) and c(b4; 0, 4) • a4: c(a4; 3, 1) and c(a4; 1, 3) • b6: c(b6; 0, 6) and c(b6; 6, 0) The choice of the resonances is based on the proximity to the working point Feed down effects are not included in the correction strategy.

  7. Introduction - IV • Other facts: • From numerical simulations it is found that non-linear correctors should not be used above 1 m of beta*. About 2 s difference depending on the use of the non-linear triplets’ correctors.

  8. Introduction - IV • Other facts: • So far the non-linear correctors have not been used in operationdue to difficulties with the temperature control (to be fixed during LS1). • This year these correctors have been used for the first time during MDs in an attempt to correct the non-linear field errors in the IR. • To be noted that these correctors provide additional sources of tune spread…

  9. Outline Introduction New layout of correctors Impact of non-linear correctors on dynamic aperture Strength specification of correctors Summary and outlook

  10. New layout of correctors - I • The proposed lattice for HL-LHC foresees a number of non-linear correctors: • In addition to those already installed in the LHC (i.e., b3, a3, b4, a4, b6) also b5, a5, and a6 are proposed. • To note that: • The D1 magnet is now superconducting. • Almost no drift left between corrector package and D1.

  11. New layout of correctors - II Feed down effects are not included in the correction strategy. • Strategy to set the correctors’ strength similar to that for the nominal machine. • Selection of the driving terms to be corrected: • a5: c(a5; 0, 5) and c(a5; 5, 0) • b5: c(b5; 5, 0) and c(b5; 0, 5) • a6: c(a6; 5, 1) and c(a6; 1, 5)

  12. Outline Introduction New layout of correctors Impact of non-linear correctors on dynamic aperture Strength specification of correctors Summary and outlook

  13. Impact of non-linear correctors on DA Clear positive impact on DA. No systematic check corrector by corrector.

  14. Outline Introduction New layout of correctors Impact of non-linear correctors on dynamic aperture Strength specification of correctors Summary and outlook

  15. Strength specification of correctors - I • Checked the distribution of strengths for the usual 60 realisations of the multipole errors in triplets and D1. • Data from IR1/5, left and right side of IRs have been combined. • Error tables used: • Triplets: June 2012 table provided by WP3 (E. Todesco). • D1: November 2012 table provided by WP3 (E. Todesco). A cross-check with a table based on improved DX magnet (S. Fartoukh) has been made too.

  16. Strength specification of correctors - II Error tables used: To note the difference between b6 and a6…

  17. Strength specification of correctors - III Main results: The impact of the difference between b6 and a6…

  18. Strength specification of correctors - IV Additionally, the required strength can be estimated (upper bound) by taking the integrated strength of the errors from triplets and D1. In summary (results are given in terms of unnormalisedKn L): Tentative proposal Upper bound for DX or D1 error tables Estimates using DX or D1 error tables

  19. Summary and outlook • Comments on the proposed non-linear correction system in the triplets: • Globally (very) effective to improve the dynamic aperture. • Proposed possible strength specification for each corrector. • Feed down effects to be reviewed? Maybe they should be included in the strategy to set the strength of the correctors.

  20. Thank you for your attention

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