12th Meeting of the FCC-ee Layout and Optics Design
ZOOM
CERN
Report important dates:
Evaluation panel 21-23 January 2026.
Report must be finalized and submitted before Christmas lab closure on the 20th of December.
Optics files:
The comparison will be done with versions 25.3 for GHC and 105 for LCC. The two lattices are in acc-models by G. Iadarola https://gitlab.cern.ch/acc-models/fcc/acc-models-fcc-ee
For GHC: tag GHC_25.3.#
For LCC: tag LCC_105.#
The MAD-X sequence and Xsuite line can be found inside the folder “lattices” t or Z
Twiss files will be provided in https://acc-models.web.cern.ch/acc-models/fcc/
Report structure:
Introduction: Overview on the two optics, detailing design and rationale behind GHC and LCC written by the optics experts.
3 pillars:
- Performance potential of the two lattices across energy points.
- Hardware and technical infrastructure requirements (magnets, power converters etc.).
- Operational considerations (tuning efficiency, switching energy points, availability)
No conclusion chapter: the review panel will provide the evaluation.
Report guidelines:
- Total length of report should be around ~100 pages.
- Short chapters (a few pages each) with main messages and quantitative comparisons, with references to the detailed studies.
- Each subsection should focus on the differences between the two lattices and not a full system/study description.
- Coherence between chapters is essential. Ghislain and Sofia will provide support.
- Focusing only on Collider for this comparison, not covering High Energy Booster.
- Ghislain and Sofia will assign a few contacts per chapter. We will also provide a list of suggestions/recommended topics to be covered and links to the presentations and minutes of the Layout and Optics Design Meetings where each topic was discussed.
Discussion:
- A. Vorozhtsov asked whether a detailed cost estimate for each lattice is needed. G. Roy replied that only a comparative cost analysis is expected that would highlight the relative differences between the two optics.
- A. Lechner suggested adding a chapter on Radiation Protection.
- M. Morrone suggested merging the SR absorbers chapter with the chapter on Vacuum.
- A. Lechner suggested adding a chapter on Beam Intercepting Devices.
- M. Le Garrec suggested adding a chapter on vibrations and impact on luminosity. G. Roy replied that this will be part of the alignment tolerances and magnetic errors chapter.