Author: Gao, Y.L.
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WEPOMS019 Beam-Beam Resonance Widths in the HL-LHC, and Reduction by Phasing of Interaction Points 2280
 
  • Y.L. Gao, S.R. Koscielniak
    TRIUMF, Vancouver, Canada
 
  Beam-beam interactions are a limiting factor in the planned high luminosity (HL) upgrade to the Large Hadron Collider (HL-LHC). Over the two main interaction regions of the LHC, a particle experiences two head-on and over a hundred long-range beam-beam interactions which drive betatron resonances in the system. Each resonance line in the space of horizontal and vertical tunes has a finite (non-zero) lock-on width. If the particles tunes fall within this width, they will eventually lock on to the resonance and be driven to large amplitude. We show that it is possible to reduce the resonances widths of a given order by using specific values of the phase advance between interaction points. This paper presents the derivation of resonance width for the weak-strong beam-beam effect, as an extension of A.Chaos width formulae for magnetic sextupoles. (A Lie-algebraic approach is used to combine the effect of the individual beam-beam impulses.) The paper then studies the lock-on width arising from two interaction regions containing 140 beam-beam impulses, and shows the cancellation of specific resonances by relative phasing of interaction points in the HL-LHC lattice.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS019  
About • Received ※ 27 May 2022 — Revised ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 22 June 2022
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