Towards Deterministic Design of MBA-Lattices

Since the pioneering work of MAX IV, multi-bend achromat (MBA) lattices have become the standard in lattice design for 4th generation lights sources as well as upgrades of 3rd generation storage rings. The distribution of the bending angle to many weak dipoles enables to reach unprecedented low emittance und highest brightness. In their most basic form, MBA-lattices consist of a repetitive unit cell and two identical matching cells on either end of the achromatic arc. The simplicity of the unit cell allows for a unique determination of the linear lattice parameters in dependence on boundary conditions defined by the project goals. Those might be the emittance, momentum compaction factor, chromaticity, as well as phase advances with respect to achieving higher order achromatic structures. A scan of optional lattice prototypes is quickly obtained. We demonstrate this concept and apply it to design an optional lattice of BESSY III, a greenfield 4th generation storage ring being currently planned at HZB, Berlin, Germany.