Design of a Meter-Scale Storage Ring for Neutral Atoms

We report on the design of a meter-scale storage ring for neutral lithium atoms. Atoms are to be guided primarily by hexapole magnetic fields produced with permanent magnets. Atoms from an existing intense atomic beam source would be loaded into the ring by optically pumping them from an unguided to a guided state. Stability requirements, similar to those encountered in high-energy particle storage rings, play a crucial role in the design. We calculate the motion of atoms in the ring taking full account of the detailed size, shape, and strength of the individual magnets. We have identified a design that is approximately mode-matched to our existing beam source, and provides stable confinement for hundreds of orbits. The primary motivation for this work is to store exceptionally large numbers of circulating atoms, which could then find application to precision measurement experiments and atom optics, and possibly to coherent matter wave physics.