Non-linear effects in the RHIC interaction regions: measurement and correction

A technique for measuring and correcting locally non-linear effects arising from field errors and feed-down from the interaction region (IR) triplets has been developed at RHIC. After a brief review of the method, we will compare measurements taken with different IR optics configurations, with beta at the interaction point ranging from 3 to 1 m. The beam data are compared with results from a realistic RHIC model, which includes measured field errors in the magnets, and simulates operational effects and corrections. A control room application has been developed for the RHIC run 2003 that allows faster measurements of non-linear effects, online plotting and fitting of non-linear terms from measurements of tune shift as a function of orbit bump amplitude. Results for local non-linear correction during run 2003 are presented.