Paper  Title  Page 

TUPPC013  Optimization of Lower Emittance Optics for the SPring8 Storage Ring  1182 


A design work of the present SPring8 storage ring is in progress to improve its performance. The linear optics has been changed to reduce the natural emittance below the nominal of 3.4 nmrad at 8 GeV, and the nonlinear optics has been optimized with a genetic algorithm to suppress the amplitudedependent tune shifts and to enlarge the dynamic aperture. As a preliminary study, the optics with the natural emittance of 2.4 nmrad at 8 GeV has been examined, theoretically and experimentally. In this optics, 1.5 times higher brilliance for 10 keV photons than the present can theoretically be expected for the standard undulator beamline. The improved optics design and its beam performance will be presented in detail. In this presentation, a optics for a future upgrade of the SPring8 (SPring8 II) will not be discussed, which is a fullscale major lattice modification, while the method we used in optimizing the nonlinear optics can also be adopted to the SPring8 II*.
* Y. Shimosaki et al., "Design Study of Nonlinear Optics for a Very Lowemittance Lattice of the SPring8 II," these proceedings. 

TUPPC014  Design Study of Nonlinear Optics for a Very Lowemittance Lattice of the SPring8 II  1185 


A feasibility of a very lowemittance storage ring has been studied for an upgrade project, SPring8 II. Its ultimate goal is to provide a superior brilliance for 0.5 ~ 100 keV photons. A sextupole bend lattice with the natural emittance of 70 pmrad at 6 GeV has been examined as the first candidate*. The nonlinear optics has been optimized to enlarge the dynamic aperture by correcting nonlinear resonances based on an isolated resonance Hamiltonian with thick lens approximation, and by noninterleaved sextupole method. A genetic algorithm, which has been examined to improve the performance of the present SPring8**, will be adopted for detailed optimization of the tunes and sextupole strength to adjust the noninterleaved scheme and to correct higher order resonances. The correction scheme of nonlinear optics and its results will be presented in detail.
*Y. Shimosaki et al., IPAC’11, TUOAB01, p. 942 (2011). **Y. Shimosaki et al., "Optimization of Lower Emittance Optics for the SPring8 Storage Ring", these proceedings. 

TUPPC015  Local Modification of Lattice of a Long Straight Section for Installing Small Gap Invacuum Undulators at SPring8  1188 


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.  