Horizontal coupling impedance of the APS storage ring

The three-dimensional wake potentials of the APS storage ring have been reconstructed according to the impedance database concept. Every wakefield-generating component in the ring was considered including small-gap insertion device (ID) chambers, rf cavities, shielded bellows, beam position monitors, synchrotron radiation absorbers, scrapers, flags, various chamber transitions, septum chambers, and pulsed kickers. In this paper the result for the horizontal wake potentials and its impedance are presented. The numerically obtained impedance has been used to investigate the experimental results. Tune shift was calculated and compared with the measurement. We also observed a horizontal focusing in the calculated wake potential of the shallow transition without rotational symmetry.