FCC-ee top-up injection
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Europe/Zurich
FCC-ee top-up injection
Present: C. Carli, Y. Dutheil, K. Keintzel, A. Lechner, T. Mori, G. Nigrelli, G. Roy, K. Skoufaris, R. Thomas, S. Yue
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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
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