Very low emittance light source storage ring

A very low emittance storage ring with an energy of 6 GeV and a circumference of 1999 m has been designed for use as a synchrotron radiation source. The ring consists of 32 ten-bend achromat cells and has a natural emittance of 34×10−12 m rad. Simulation showed that the horizontal dynamic apertures at the center of a straight section are −4.2 and +2.9 mm and that they can be increased to −5.4 and +7.9 mm, respectively by changing the strength of sextupole magnets used for chromaticity correction. Emittance growth due to intrabeam scattering and Touschek lifetime were estimated. With 0.1% coupling, the horizontal emittance was 109×10−12 m rad, and the lifetime was 0.17 h for a 0.1-mA bunch current. With 100% coupling, it was 21×10−12 m rad, and the lifetime was 2.0 h. These results indicate that a storage ring with picometer-order emittance is possible with realistic parameters and is thus promising as a next-generation light source.