This work reports an enhanced polarization and mechanisms in optically pumped (OP) hyperpolarized He3 in the presence of He4. The cells contain Rb metal, 60-torr N2, and different pressures of He3 and He4. In the absence of He4, the polarization of He3 increases monotonically from 4.5% to 8% when the pressure of He3 is increased from 300 to 1500 torr. In the presence of 1850-torr He4 gas, the polarization of He3 is enhanced from 7% to 30% for a cell containing 600-torr He3 and 60-torr N2. The wall relaxation factors X for OP cells with and without buffering He4 gas were derived. It was found that the He4 gas confines the He3 atoms to a diffusion-limited region which effectively reduces the wall relaxation factor X. Mechanisms contributed to relaxation are addressed and discussed.
|Journal||Physical Review A - Atomic, Molecular, and Optical Physics|
|Publication status||Published - 2010 Mar 26|
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics