In KEKB, synchrotron radiation interferometers (SRMs) are used for measuring the transverse beam sizes. There is also a tool for enlarging the vertical beam size intentionally by making an asymmetric bump, called an ``iSize'' bump, at one of the strongest non-interleaved sextupole magnets in each KEKB ring. The calibrations of the SRMs were checked by comparing the measured vertical beam sizes with those calculated using the computer code ``SAD''. The obtained correction factors are 1.000±0.045 for HER and 0.971±0.060 for LER, which are consistent with the calibration factors of SRMs\cite{SRMcalib} within errors. Using the obtained calibration factor, x-y coupling of each ring was calculated .
@article{arxiv.0707.0539,
title = {Synchrotron Radiation Interferometer Calibration Check by Use of A Size Control Bump in KEKB},
author = {N. Iida and J. Flanagan and Y. Funakoshi and K. Oide},
journal= {arXiv preprint arXiv:0707.0539},
year = {2007}
}