Estimation of Betatron Coupling and Vertical Dispersion for Spring-8 Storage Ring

The betatron coupling is one of the most important parameters of storage rings for high brilliant light source. By the precise alignment of the magnets [1] and the proper COD correction [2], the SPring-8 storage ring succeeded in achieving the very small linear betatron coupling without skew quadrupole corrector magnets. To prove this fact, we study the betatron coupling of the SPring-8 storage ring. The measurement of the vertical emittance of the stored beam is the most preferable method to know the coupling. But, since the vertical emittance of the SPring-8 storage ring is too small to measure, at present we have not yet measured it. Hence, by measuring the dependencies of the various ring parameters on the betatron coupling, we prove the validity of our estimation of the betatron coupling.