PEP as a synchrotron radiation source: status and review

The electron-positron collider, PEP, is a 15-GeV storage ring built and operated for high-energy physics. Two insertion device beam lines are operational, each illuminated by 2-m-long, 77-mm period undulator magnets. In parasitic operation on high-energy-physics runs, they provide photons above 10 keV, with a peak brightness of 10¹⁶ photons/(s-mm²-mrad²) within a 0.1% bandwidth. In tests of a low-emittance mode of operation at 7.1 GeV, horizontal emittances of about 5 mm-rad were measured, which is about the same as that planned for the new third generation X-ray sources. At a current of 15 mA at 7.1 GeV, the present undulators deliver photon beams from 2.7 to 14 keV with a peak brightness of about 10¹⁷. Higher performance can be achieved with longer insertion devices optimized for these energies. Future operation in both parasitic mode and dedicated low emittance mode is planned