Realizations of polarized targets in storage rings

While particle storage rings generally provide a large average current, they require ultra-thin targets in order to maintain a reasonable lifetime of the beam. Targets composed of polarized atomic gas are well-suited for use in storage rings because of their thinness and the high degree of purity and polarization possible. Several of these so-called internal targets have been developed and successfully used to measure scattering asymmetries at Novosibirsk; future experiments have been proposed at Bates, NIKHEF, and HERA, for example, which also rely on these techniques. The methods that have so far proved feasible for producing and storing highly polarized atoms will be reviewed. 6 refs., 1 fig