Polarimetry on dense samples of spin-polarized 3He by magnetostatic detection

A very sensitive low-field fluxgate magnetometer is used to detect the static magnetic field produced by dense samples of spin-polarized He-3 gas contained in spherical glass cells at pressures around several bars. The He-3 nuclear polarization can be extracted with high precision Delta P/P < 1% by utilizing magnetostatic detection in combination with adiabatic fast-passage spin reversal. The polarization losses can be kept well below 0.1% thus making this type of polarimetry almost non-destructive. More simply even, P can be measured with reduced accuracy by the change of field when the cell is removed from the fluxgate. In this case the accuracy is limited to about 10% due to the uncertainties about the susceptibilities of the cell walls.