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Dense samples (10–100 bar cm) of nuclear spin polarized 3He are utilized in high energy physics, neutron scattering, atomic physics, and magnetic resonance imaging. Metastability exchange optical pumping can rapidly produce high 3He polarizations (≈80%) at low pressures (few mbar). We describe a polarized 3He gas compressor system which accepts 0.26 bar l h-1 of 3He gas polarized to 70% by a 4 W neodymium doped lanthanum magnesium hexaluminate (Nd:LMA) laser and compresses it into a 5 bar cm target with final polarization of 55%. The spin relaxation rates of the system’s components have been measured using nuclear magnetic resonance and a model of the 3He polarization loss based on the measured relaxation rates and the gas flow is in agreement with a 3He polarization measurement using neutron transmission. [ABSTRACT FROM AUTHOR]

A sapphire cell was used to obtain a high 3He nuclear polarization by means of spin-exchange optical pumping. The phase-shift difference between ordinary and extraordinary rays is well controlled using the thickness of the birefringent sapphire window so that a high circular polarization is obtained in the cell. Neutron transmission through the polarized 3He gas was measured as a function of neutron energy. A large 3He polarization of 63±1% was obtained at a 3He pressure of 3.1 atm. Neutron polarizations of 97 and 90 % were obtained with transmission rates of 15 and 22 % at 10 and 20 meV, respectively. [ABSTRACT FROM AUTHOR]