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 4 x 4 beam matrix can be misleading in the presence of errors. The authors suggest more robust tuning procedures for minimizing linear coupling.