Weak focusing low emittance storage ring with large 6d dynamic aperture based on canted cosine theta magnet technology

Abstract

We developed a low emittance electron storage ring with large 6D dynamic aperture. Contrary to the traditional approach using strong focusing magnetic cells with optimized (and large) horizontal phase advance, which yields huge natural chromaticity, we employed a relatively weak focusing lattice with low chromaticity per cell and, consequently, wide on- and off-momentum dynamic aperture. Inevitable for weak focusing emittance growth, we compensated by slicing the lattice into many short, with small bending angle, elementary periodic cells. To reduce the size, we superimposed focusing gradient and chromaticity compensating sextupole components over the dipole field utilizing superconducting magnets based on the Canted Cosine Theta (CCT) winding technology. The result is a model lattice with 50 pm horizontal emittance at 3 GeV beam energy, with 400-500 m circumference and large 6D aperture.