MEASUREMENT AND OPTIMIZATION OF LOCAL COUPLING FROM RHIC BPM DATA

Global coupling in RHIC is routinely corrected by using three skew quadrupole families to minimize the tune split (ΔQmin). In this paper we propose to re-optimize transverse coupling by minimizing the resonance driving terms (RDT's) and the coupling matrix (|(bar C)|/γ2) in two steps: (1) Identify locations with coupling sources by inspection of the driving terms and the C-matrix around the ring and minimize the discontinuities and (2) Find the best configuration of the three skew quadrupole families to minimize both ΔQmin and RDTs (f1001). The measurements of f1001 and |(bar C)|/γ2 at injection and top energy to identify local coupling sources are presented