Simultaneous global coupling and vertical dispersion correction in RHIC

Residual vertical dispersion in the order of +/−0.2 m (peak to peak) has been measured at store energies for both polarized proton and heavy ion beams in RHIC. The hypothesis is that this may have impact on the polarization transmission efficiency during the energy ramp, the polarization lifetime at store and, for heavy ions, the dynamic aperture. An algorithm to correct global coupling and vertical dispersion simultaneously using existing skew quadrupoles was developed. Measured coupling and vertical dispersion functions acquired before and after correction are presented.