• K. Tsumaki
  JASRI/SPring-8, Hyogo-ken

We indicated that a storage ring with picometer-order emittance is possible with realistic parameters and is promising as a next generation synchrotron radiation source* and applied it to the SPring-8 storage ring**. The storage ring had the same circumference as that of the SPring-8 storage ring, but had not four long straight sections that SPring-8 storage ring has. Accordingly, the storage ring beam line is slightly different from that of the SPring-8 and the positions of photon beam lines are also different from the existing one. To avoid this, a storage ring with four long straight sections has been studied and was found that the storage ring with the same beam line positions as the existing one is possible. The storage ring consists of twenty ten-bend achromat cells, four five-bend achromat cells and four long straight sections. The long straight section length is 34.0 m and the short one is 6.6 m. The natural emittance is 10⁸ pm-rad. The maximum brightness is 2.5×10²² photons/s/mm**2/mrad**2 in 0.1% BW with 200 mA beam current, about 160 times brighter than SPring-8. In the end I mention that this ultra-low emittance storage ring is only a result of personal design study.

* K. Tsumaki and N. Kumagai, Nucl. Instr. and Meth. A 565 (2006) 394.
** K. Tsumaki and N. Kumagai, EPAC'06, 3362.