Enhanced polarization and mechanisms in optically pumped hyperpolarized {sup 3}He in the presence of {sup 4}He
- Institute of Electro-Optical Science and Technology, National Taiwan Normal University, Taipei 116, Taiwan (China)
- Graduate Institute of Applied Physics/Department of Physics, National Taiwan University, Taipei 106, Taiwan (China)
- Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu 30013, Taiwan (China)
This work reports an enhanced polarization and mechanisms in optically pumped (OP) hyperpolarized {sup 3}He in the presence of {sup 4}He. The cells contain Rb metal, 60-torr N{sub 2}, and different pressures of {sup 3}He and {sup 4}He. In the absence of {sup 4}He, the polarization of {sup 3}He increases monotonically from 4.5% to 8% when the pressure of {sup 3}He is increased from 300 to 1500 torr. In the presence of 1850-torr {sup 4}He gas, the polarization of {sup 3}He is enhanced from 7% to 30% for a cell containing 600-torr {sup 3}He and 60-torr N{sub 2}. The wall relaxation factors X for OP cells with and without buffering {sup 4}He gas were derived. It was found that the {sup 4}He gas confines the {sup 3}He atoms to a diffusion-limited region which effectively reduces the wall relaxation factor X. Mechanisms contributed to relaxation are addressed and discussed.
- OSTI ID:
- 21408456
- Journal Information:
- Physical Review. A, Vol. 81, Issue 3; Other Information: DOI: 10.1103/PhysRevA.81.033422; (c) 2010 The American Physical Society; ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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