Sextupole Magnets With Variable Tilting Angle for SuperKEKB

Abstract

SuperKEKB, which is an electron-positron collider with a design peak luminosity of 8 × 10 35 /(cm 2 s), is under construction. The luminosity is 40 times higher than the world record set by its predecessor, KEKB B-factory. The design of SuperKEKB is based on the “nanobeam scheme,” which is a low-emittance lattice. To achieve the low-emittance beam, the chromaticity of X-Y coupling at the interaction point (IP) should be controlled. Skew sextupole magnets are found to be effective in reducing the beam size at the IP during the KEKB operation. A novel idea of tilting normal sextupole magnets to control the ratio of the skew to the normal field component has been proposed for the positron ring at SuperKEKB. This paper presents the design and the fabrication of the tilting sextupole magnet system.