Design of the PEP-II Low-Energy Ring

The PEP-II Project, a collaboration of SLAC, LBL, and LLNL, began construction in January 1994. Since the Conceptual Design Report (CDR) was issued in June 1993, considerable progress has been made at refining and optimizing the Low-Energy Ring. Lattice design has progressed considerably, with solutions obtained for the chromatic correction of the IR and new, more relaxed, parameters for the required wigglers. Based on the latter change, the number of RF stations was reduced from 5 to 4. A new concept for the are vacuum system has been adopted, based on an antechamber configuration with discrete photon stops pumped by titanium sublimation pumps. Designs for the are dipoles and quadrupoles have been developed in collaboration with IHEP (Beijing) and these magnets are now being fabricated there. A new configuration for the high-power wiggler photon dumps has been developed and is in the detailed design phase.