Ultra-Low Field NMR of ${\rm UF}_{6}$ for $^{235}{\rm U}$ Detection and Characterization

We have demonstrated the first ultra-low field (ULF) nuclear magnetic resonance measurements of uranium hexafluoride (UF
₆
), which is used in the uranium enrichment process. A sensitive non-invasive detection system would have an important role in non-proliferation surveillance. A two-frequency technique was employed to remove the transients induced by rapidly switching off the 50 mT pre-polarization field. A mean transverse relaxation time T
₂
of 24 ms was estimated for the un-enriched UF
₆
sample measured at a mean temperature of 80degC.