Field Measurements of the Kek B-factory Dipole and Wiggler Magnets

The KEK B-Factory (KEKB) [1] consists of 3.5 GeV positron (LER) and 8.0 GeV electron (HER) rings and has more than 290 dipole and 150 wiggler magnets. Both the LER and the HER use four types of dipole magnets. Wiggler magnets are used for the LER. Three long flipflop coil systems were used to measure the transverse distribution of the integrated magnetic field along the beam direction. Each dipole magnet was measured using one of these system according to its size. The wiggler magnets were measured using a rotating coil which contains one long coil and two half coils. The long coil measured the net residual integrated magnetic field and each half coil measured the magnetic flux of each pole. Field mapping has also been performed for at least one of each type of magnet. Effective length and field distribution along the beam direction were measured by using a flipflop mapping coil system. The absolute magnetic field strength at dipole center was calibrated by NMR. These measurement results are summarized.