Racetrack lattices for low-medium-energy synchrotrons

In design of magnet lattice for an accelerator the various requirements depending on machine specifications can be met. The authors discuss the possible lattice design for low-energy ( gamma /sub max/ approximately=/10) and medium-energy ( gamma /sub max/ approximately=30/50) high-intensity synchrotrons. They are restricted and concentrate on those lattices in which the following requirements are fulfilled: the transition energy gamma /sub t/ is kept (or low) enough to satisfy many conditions of beam stability; the accelerator ring has a racetrack shape with two 180 degrees arcs and two long dispersion-free straight sections desired for RF cavities, injection and extractions elements, Siberian Snakes, etc. and the dynamic aperture in presence of chromaticity-correcting sextupoles is sufficiently large. A careful analysis shows that these requirements are not really contradictory ones, but often it is hard to fulfil them together.<>