Precision Measurement of Coupling Ellipses Parameters in a Storage Ring

Eigen-mode coupling ellipses’ tilt angles and axis ratios can be precisely measured with a Model-Independent Analysis (MIA) of the turn-by-turn Beam Position Monitor (BPM) data from resonance excitation of the betatron motion. For each BPM location one can measure 4 parameters from the two resonance excitation, which completely describe the linear coupling of the location. Results from application to PEP-II LER storage ring are presented.