Lattice design for an ultra-low emittance synchrotron light source

In this paper, we investigate a lattice design for an ultra-low emittance storage ring with intermediate energy of 3  GeV and circumference of 576  m. We present the design results for a seven-band achromat lattice with the natural emittance of 90  pm-rad. The base line is based on 20 straight sections with the length of 6  m. The minimum distance between different magnets is 10  cm and it has been tried to keep the lattice structure as simple as possible. The brilliance of radiated synchrotron radiation from a 2.24  m In-vacuum undulator installed in the lattice is 4×1021photons∕smm2mm2mrad20.1%BW . We will address the challenging points of designed ultra-low emittance storage ring lattice such as strong nonlinearity and collective effects. The dynamic aperture of the lattice is comparatively sufficient for off-axis injection and the lifetime is relatively large without using any harmonic cavity. Since the proposed lattice structure in some aspects is similar to MAX IV storage ring, we will make some comparison between two lattices in different sections.