A Review of Laser Driven 3 He Neutron Polarizers

Abstract

Neutron beam polarization by transmission through a sample of laser polarized gaseous ³He is rapidly advancing toward practicality and broad application. Two methods have been developed for polarization of ³He nuclei: exchange of polarization from optically pumped metastable ³He and exchange from optically pumped Rb. The metastability exchange technique is currently used to power a sort of factory capable of producing on the order of liters per hour of ³He that fills bottles that can be transferred to a specific experiment. The spin exchange technique has benefited from industry’s production of high powered laser diode arrays, and complete polarizers can be installed in individual experiments. Though there is no clear advantage to one technique or the other, the competition has provided us with a choice of the best technology for a particular experiment or instrument.