The beam-beam interaction in the Tevatron collider sets limits on bunch intensity and luminosity. These limits are caused by a tune spread in each bunch which is mostly due to head-on collisions, but there is also a bunch-to-bunch tune spread due to parasitic collisions in multibunch operation. We propose to compensate these effects with the use of a countertraveling electron beam, and we present general considerations and physics limitations of this technique.

This paper resumes a series of investigations devoted to the influence of ground motion on linear colliders in the TeV energy range. We attempt to model a variety of measured ground motion data and then to calculate the behavior of beams in the linear collider affected by this motion. An adequate description of ground motion is found in the form of a two-dimensional power spectrum P(,k) that carries information both about the time and space dependences of displacements. We then discuss the use of this spectrum to calculate the time evolution of beam position and beam size at the interaction point. A few approximations of this spectrum for typical seismic conditions are proposed for a wide range of and k based on the results of absolute and relative seismic measurements. Examples of calculations of the time evolution of the beam size and position in the final focus system of a linear collider are presented. Estimations of the influence of feedback are made.

The beam-beam interaction in the Tevatron collider sets limits on bunch intensity and luminosity. These limits are caused by a tune spread in each bunch which is mostly due to head-on collisions, but there is also a bunch-to-bunch tune spread due to parasitic collisions in multibunch operation. We propose to compensate these effects with use of a countertraveling electron beam, and present general considerations and physics limitations of this technique.

No abstract

Spectral analysis has been used to study emittance growth due to chromatic effects in future linear colliders. This formalism allows us to study the effects of static initial misalignments, as well as the effects of magnet displacements produced by ground motion, the latter described adequately by the two-dimensional power spectrum P(,k). The effectiveness of correction techniques, envisaged in long linacs to recover the small required emittance, has been also evaluated by this spectral approach. For illustration, analytical predictions for the ''one-to-one'' algorithm and the ''adaptive alignment'' method are given and compared to numerical simulations.