Present: C. Carli, Y. Dutheil, K. Keintzel, A. Lechner, T. Mori, G. Nigrelli, G. Roy, K. Skoufaris, R. Thomas, S. Yue

• automatic summary here is inaccurate & misleading 

• Injection top-up baseline and MKI
  • Baseline needs to remain on-axis to minimise noise to the experiments
  • Present optics and MA does not allow on-axis for Z and W mode
    • Hybrid scheme allows to reduce the momentum offset at the expense of a betatron offset
    • W-mode baseline is hybrid
    • Z-mode with lower MA after beam-beam is added also requires hybrid
  • Next steps
    • On-axis injection scheme study in LCC lattice
    • Compatible optics for both conventional and MKI injection
    • Requirements on the field distribution of MKI
    • Real threading of the beam trajectory upstream the injection point (F-quad)
• Injection requirements
  • Change at every energy mode since the equilibrium emittances increase with energy due to SR
  • Present limitation comes from optics and MA, already a lot of effort put into DA/MA -> need to refocus on adjusting the optics for the injection scheme
  • Presently keeping the 0.95% injection
• Ring Optics & Technical Insertions
  • Presently universal technical insertion for the all the SS : length and chromaticity are the same for all 4
  • Ghislain will investigate the possibility of having special optics for each of the 4 straight sections
  • Action Ghislain : will investigate the possibility of a new GHC lattice following requirements
    • (added after the discussion)
    • At injection point
      • Open physical space at the injection point of >5 m
      • Alpha_x and Dpx ~0
      • Beta_x = 1000 m and D_x = 1.8m
    • For conventional, bump injection
      • 2 kickers, pi/2 before and after the injection point
      • Same beta_x at each kicker
    • For MKI injection scheme
      • Non linear kicker needs compensation station with same kicker, but upstream the injection
      • Compensation primarily in horizontal, possible effect in vertical not discussed yet
      • compensation upstream with -I transform wrt the injection point
      • Compensation also with -Dx and -Dxp  wrt the injection point
• Giulia is working on the injection losses and background it may cause
  • Presently on the Z-mode, with Kyriacos lattice
  • Critical for experiments but presently no input from detectors on levels of acceptable losses
  • Question of the scarping on the injection septum with conventional scheme, that could create background on the experiment
• Existing collider injection repo
  • https://gitlab.cern.ch/abt-optics-and-code-repository/projects/collider-injection-fcc-ee
  • Repo contains tracking and phase-space plots, with submodules and lattice modifications needed to place the injection point
  • Aims at ensuring everyone uses the same lattices, model and settings
  • Aims at centralising the various contributions, either in-repo or linked sub-modules,

Actions

• Action Ghislan and Rogelio : discussions within ABP to identify a primary contact to follow the beam dynamics/rings/collective effects aspects of top-up injection
• 09/01  organisation and chairing of the working group to be discussed after ABP main contact/s is/are identified
• action Yann 09/01 add a conversion of Kevin's result for acceptable betatron offset of injected beam in number of sigma
• Action Ghislain 06/02 : investigate the possibility of generating a new optics for the straight sections