CESR plus

The Cornell Electron Storage Ring (CESR) operates with seven bunches per beam and 11 mA per bunch to yield a peak luminosity of 1×10³² cm^-2 s^-1 at each of two interaction points. An electrostatic orbit distortion separates the beams at the 12 parasitic crossings. The beam-beam limited luminosity can be significantly increased by reducing the number of interaction points to one. The fraction of a radiation damping time per collision at the remaining interaction point is thereby doubled. Because one of two sets of low-beta optics can be removed, the integer part of the horizontal tune can be increased to 13 from nine, permitting operation with 14 bunches per beam, and the beam width at the single interaction point can be enhanced. Currents of about 300 mA per beam will be required to operate the upgraded machine at its beam-beam limit. The reconfigured storage ring with a beam-beam limited luminosity in excess of 5×10³² cm^-2 s^-1 and the associated upgrade of the single beam current carrying capability are described