First Considerations on Beam Optics and Lattice Design for the Future Electron-Positron Collider FCC-ee

The Future Circular Collider (FCC) study includes the design of a 100-km electron positron collider (FCC-ee) with collision energies between 90 GeV and 350 GeV. This paper describes first aspects of the design and the optics of the FCC-ee collider, optimised for four different beam energies. Special emphasis is put on the need for a highly flexible magnet lattice in order to achieve the required beam emittances in each case and on the layout of the interaction region that will have to combine an advanced mini-beta concept, an effective beam separation scheme and a local chromaticity control to optimise the momentum acceptance and dynamic aperture of the ring.