More bunches in LEP

The LEP (Large Electron Positron Collider) has been designed to operate with four bunches in each beam. For the physics interest, the possibility of increasing the number of bunches in order to provide a higher luminosity at the Z⁰-resonance is considered. It is suggested that unwanted head-on collisions can be avoided by horizontal separation in a fourfold pretzel scheme analogous to the one used at the Cornell Electron Storage Ring (CESR) and requiring additional electrostatic separators working independently of those already foreseen. Residual beam-beam effects are minimized by selecting an optimum combination of bunch number and optics. Modifications of the standard LEP optics and RF system are necessary. The performance which can be expected with such a scheme, the criteria for evaluating it, and the factors which limit it are discussed