POLARIZATION OF He$sup 3$ GAS BY OPTICAL PUMPING

The process of He/sup 3/ nuclear polarization by metastability exchange with optically pumped metastable He/sup3 / atoms is described andd experimental details given. Phenomenological theories are presented which explain the optical signals snd the time variation of the polarization. The polarization is measured both optically and by nuclear magnetic resonance. Relaxation of the nuclear spins by diffusion through magnetic field gradients is discussed. When gradients are small, nuclear relaxation times as long as 4000 sec were measured. The maximum polarization achieved was 40 plus or minus 5% in He/sup 3/ gas at a pressure of one mm Hg. (auth)