Operating Results from SPEAR

Initial operating experience with the SLAC electron-positron storage ring SPEAR is described. A luminosity of 1.2 × 1031 cm-2 sec-1 has been achieved and two-beam interaction effects are described. A single-beam coherent instability, which can be suppressed either by control of the ring chromaticity or by feedback, has been observed. Current-dependent bunch lengthening and widening have been observed, and experiments indicate that these phenomena may be associated with an increase in the energy spread of the beam. Procedures to increase the luminosity to the design value are discussed. Plans to increase the maximum beam energy of SPEAR to 4.5 GeV are described.