ELECTRON-ION COLLIDER AT CEBAF: NEW INSIGHTS AND CONCEPTUAL PROGRESS *

We report on progress in the conceptual development of the proposed high luminosity (up to 10 35 cm -2 s -1 ) and efficient spin manipulation (using “figure 8” boosters and collider rings) Electron-Ion Collider at the CEBAF. This facility would use a polarized 5-7 GeV electron beam from a superconducting energy recovering linac with a kicker-operated circulator ring, and a 30-150 GeV ion beam in a storage ring (for polarized p, d, 3 He, Li and unpolarized totally stripped nuclei up to Ar). Ultra-high luminosity is envisioned to be achieved with very short crab-crossing bunches at 1.5 GHz repetition rate. Our recent studies were concentrated on understanding beambeam interaction, ion beam instabilities, luminosity lifetime due to intrabeam scatterings, ERL-ring synchronization, and ion spin control. We also proposed a preliminary conceptual design of the interaction region. These studies have been incorporated into the development of the luminosity calculator and the formulation of minimum requirements for the polarized electron sources.