The incoherent beam-beam effect in linear-on-ring colliders

Linac-on-ring schemes for high-luminosity colliders are based on collisions between an intense positron beam in a conventional storage ring and relatively low-intensity bunches of electrons from a high-repetition rate superconducting linac. The electrons are highly disrupted as they pass through the positron bunch and the electron bunch envelope suffers a longitudinal pinch that varies in form according to the chosen beam parameters. This pinch must be incorporated into any beam-beam simulation program that is used to study the stability of the positron beam. The synchrobetatron resonances due to collision point oscillations are particularly sensitive to the form of the pinch and also to any longitudinal jitter on the electron bunches.<>