Optics diagnostics and tuning for low emittance beam in KEK-ATF damping ring

The target of KEK-ATF is producing electron beam with vertical emittance of 0.01 nm-rad (1/spl times/10/sup -11/ m-rad). Corrections of the dispersions are essential to achieve the low emittance. Because the actual optics of the beam line should be known for these corrections, beam based optics diagnostics has been performed. Simulations showed the validity and the accuracy of the method. Effects of skew quadrupoles have also been studied.