Study of the magnetic coupling between quadrupole and dipole corrector magnets for the KEK B-factory

Most of the quadrupole magnets in the KEK B-factory are accompanied by a set of vertical and horizontal dipole corrector magnets in both the LER and HER rings. The typical separation between a quadrupole and a dipole corrector magnet is 202 mm, as measured from the laminated ends. This corresponds to ~3.7 (2.4) times of the bore radius of a quadrupole magnet in the arc (straight) sections. Since the series measurements of quadrupole magnets were performed without any magnetic material nearby, the effect of the magnetic coupling from the corrector dipole magnet in the actual beam line needs to be measured. Measurements of the coupling between quadrupole and dipole corrector magnets are presented