
 K. Soutome, T. Fujita, K. Fukami, K.K. Kaneki, C. Mitsuda, H. Ohkuma, M. Oishi, Y. Okayasu, S. Sasaki, J. Schimizu, Y. Shimosaki, M. Shoji, M. Takao, Y. Taniuchi, C. Zhang
JASRI/SPring8, Hyogoken, Japan
 M. Hasegawa, K. Kajimoto, T. Nakanishi
SES, Hyogopref., Japan



In the SPring8 storage ring there are four magnetfree long straight sections (LSS) of about 30m. Recently we locally modified one of these sections by installing two quadrupoletriplets and divided it into three subsections. The vertical beta at the middle of each subsection was lowered to 2.5m so that small gap invacuum undulators with a short period (min. gap: 5.2mm, period: 19mm) can be installed to build a high performance beamline for inelastic Xray scattering. After modifying the lattice, however, the symmetry of the ring is lowered and, in general, it becomes difficult to keep sufficient dynamic aperture (DA) and momentum acceptance (MA). We solved this problem by combining the betatron phase matching, local chromaticity correction in LSS and cancellation of nonlinear kicks due to sextupoles used for this correction. We could then recover DA and MA to almost the same level for the original one. The beam commissioning of the new lattice has successfully been finished, and from September 2011 it is used in useroperation. We will report our method of realizing a storage ring lattice having a very low symmetry and review the operation performance of the modified lattice.

