Tailoring the Performance of LEP

Experience gained with existing e+e- storage rings and the accumulation of understanding derived from theory and simulation allow more accurate prediction of the performance of future machines like LEP. We describe the relation of luminosity to other quantities of interest to the machine users, such as energy spread, beam sizes or polarization. For example, the maximum event rate on a narrow resonance may not correspond to the condition of maximum luminosity. Partial control of beam parameters is available through damping partition number variation, coupling adjustment, wigglers, etc. but a proper estimation of the necessary operating conditions must include a self-consistent, realistic treatment of the beam-beam effects which also determine performance. The established correlation between theory and simulation of the beam-beam effect in several regimes has been exploited in the search for good working points. Single particle stability (dynamic aperture) has been improved at the same time.