Upgrade of the CEBAF acceleration system

Long-term plans for CEBAF at Jefferson Lab call for providing 12 GeV in the middle of the next decade and 24 GeV after 2010. Such energies can be achieved within the existing footprint by fully populating the accelerator tunnel with cryomodules capable of twice the operating voltage of the existing ones within the same length. In particular, this requires the development of superconducting cavities capable of operating at gradients above 12 MV/m and Q/spl sim/10/sup 10/. An R&D program for the development of the cryomodules is under way and will be presented, as well as various options for the upgrade path.