A lattice for a 5 GeV ERL in the CESR tunnel

It has been proposed to build an Energy-Recovery Linac (ERL) based synchrotron-light facility at Cornell. Due to the high beam quality of a linac with photo injector, such a facility has the potential to provide better X-ray radiation than ring-based sources. To take advantage of the existing circular accelerator CESR for this 5 GeV ERL, it has been suggested that the linac should be split in sections that are at angles to each other and that half the CESR ring should be used as a return arc to connect the end of the last linac section to the beginning of the first. Here we specify the minimum optical requirements on such a layout and show a possible lattice for an ERL that uses CESR.