| Applications of polarized neutrons are plentiful in nuclear, particle, and condensed matter physics. Many techniques exist for the polarization of neutrons, from supermirror polarizers, to polarized proton scatterers, to crystal monochrometers. Due to many recent technological advances, the development of spin filters based on polarized 3He has also been made possible, and for certain applications, their use has many unique advantages.; Two methods have been developed for the polarization of ground state 3He gas atoms: spin exchange with optically pumped Rb, and optical pumping of metastable 3He followed by metastability exchange collisions. This work first discusses the development of 3He neutron spin filters based on the metastability exchange technique. In this technique, low pressure (∼1–2 torr) 3He gas in its 3S1 state is polarized by optical pumping using circularly polarized 1083 nm laser light. The greatest technical difficulty in this method is to compress the highly polarized 3He gas to a thickness (5–50 atm-cm) appropriate for use as a neutron spin filter, while maintaining a high degree of the initial polarization. To this end, a non-magnetic compression system was constructed. Great care was taken to ensure magnetic and vacuum purity in the system. The efficiency of compression and maintenance of the polarization in compression have been studied and are discussed, as are future directions and hope for improvement.; In the latter part of this work, an application of polarized 3He spin filters is discussed. At the LANSCE pulsed neutron source, a measurement of the neutron beam polarization with an absolute accuracy of 0.2% in the energy range from 40 meV to 10 eV has been performed. A relative transmission measurement technique using an optically-pumped polarized 3He spin filter was used. For this measurement, 3He was polarized using the Rb spin-exchange method. The capability of performing accurate absolute measurements of neutron beam polarization opens a number of exciting opportunities in fundamental neutron physics and in neutron scattering. We describe the measurement technique, present our results, and discuss some of the potential limitations of the method. |
