Measurement and Correction of Cross-Plane Coupling in Transport Lines

In future linear colliders the luminosity will depend on maintaining the small emittance aspect ratio delivered by damping rings. Correction of cross-plane coupling can be important in preventing dilution of the beam emittance. In order to minimize the vertical emittance, especially for a flat beam, it is necessary to remove all cross-plane (x-y) correlations. This paper studies emittance measurement and correction for coupled beams in the presence of realistic measurement errors. The results of simulations show that reconstruction of the full 4x4 beam matrix can be misleading in the presence of errors. We suggest more robust tuning procedures for minimizing linear coupling.