About Recent Improvement in the Luminosity at KEKB

Abstract

A new luminosity record of 21.08×10³³ cm^－2s^－1, which is the world record at present, was achieved at KEKB in the spring run of 2009. The previous record was 17.60×10³³cm^－2s^－1 achieved in November 2006. This significant improvement in the luminosity was brought mainly by the newly installed skew-sextupole magnets, which are believed to correct the chromaticity of x-y coupling at IP. In addition, the increase of the HER beam current also contributed to the luminosity improvement. This beam current increase became possible by solving the physical aperture problem around the crab cavities.