A SPIN REFRIGERATOR POLARIZED TARGET FOR NUCLEAR-PHYSICS EXPERIMENTS

A cryogenic polarized proton target has been developed for use in nucl ear physics experiments. This target makes use of the ''spin refrigera tor'' mechanism to produce the polarization, instead of the microwave pumping used in conventional polarized targets. The design, operating procedures and experience are discussed. While the polarization is low , typically 40% during actual experiments, other advantages make the t arget useful for certain applications. These include low development a nd operating costs, magnetic fields as low as 590 G during data acquis ition, open geometry, the possibility of large-area targets, and the a bility to change the polarization direction on a 10 min time scale.