Global COD correction of SAGA-LS storage ring

SAGA light source (SAGA-LS) [1] is a medium size light source facility which starts user-operation from February, 2006. The stored beam orbit has been corrected by a closed orbit correction system consisted of 24-beam position monitors (BPMs), 40-steering magnets and PC- Lab View based control system [2]. The singular value decomposition (SVD) method has been applied for the global closed orbit distortion (COD) correction by using a measured response matrix (S-matrix). As the result, the standard deviation of the orbit error around the ring was reduced to 10 mum both for horizontal plane and for vertical plane. The linear lattice of the ring has been calibrated to reproduce the measured S-matrix. The calibrated lattice well reproduces the S-matrix, but does not reproduce the machine function so well. The machine function shows a beta-beating in vertical plane.