Electron-ion colliders with a center of mass energy between 15 and 100 GeV, a luminosity of at least 1033 cm−2S−1, and a polarization of both beams at or above 80% have been proposed for future studies of hadronic structure. The scheme proposed here would accelerate the electron beam using the CEBAF recirculating linac with energy recovery. If all accelerating structures presently installed in the CEBAF tunnel are replaced by ones with a ∼20 MV/m gradient, then a single recirculation results in an electron beam energy of about 5 GeV. After colliding with protons/light ions circulating in a figure-of-eight storage ring (for flexibility of spin manipulation) at an energy of up to 100 GeV, the electrons are re-injected into the CEBAF accelerator for deceleration and energy recovery. In this report several layout options and their respective feasibilities will be presented and discussed, together with parameters which would provide a luminosity of up to 1 · 1035 cm−2s−1. The feasibility of combining such a collider at a center-of-mass energy √s of up to 43 GeV with a fixed target facility at 25 GeV is also explored.
