Design Guidelines for the Injector Complex of the FCC-ee

The design of the injector of the FCC-ee, a high-luminosity e+/e- circular collider of 100 km in the Geneva area, is driven by the required particle flux for ring filling or top-up and for a variety of energies, from 45.6 to 175 GeV. In this paper, a set of parameters of the injector complex is presented, fulfilling the collider needs for all running scenarios. In particular, the challenges of the booster ring design are detailed, focusing on issues of optics, layout, low bending fields, injection schemes to the collider for maximizing transfer efficiency and synchrotron radiation handling