Hyperfine Structure and Nuclear Moments of Thulium-166

The hyperfine structure of 7.7-h ${\mathrm{Tm}}^{166}$ has been studied using the atomic-beam magnetic resonance technique. The results are $\mathrm{}\left|A\right|=19\mathrm{}\pm 6$ Mc/sec, $\mathrm{}\left|B\right|=7700\mathrm{}\pm 300$ Mc/sec, and $\frac{B}{A}<0\mathrm{}$. Values of the nuclear moments are calculated from the hyperfine interaction constants $A$ and $B$ for ${\mathrm{Tm}}^{166}$ using known values for $A$, $B$, ${\mu }_I$, $Q$ for ${\mathrm{Tm}}^{170}$. Results for ${\mathrm{Tm}}^{166}$ are $\left|{\mu }_I\right|=0.05\mathrm{}\pm 0.03$ nm and $\mathrm{}\left|Q\right|=4.6\mathrm{}\pm 0.7$ b with $\frac{Q}{{\mu }_I}>0\mathrm{}$. These results are discussed from the standpoint of the deformed-nucleus model of Mottelson and Nilsson.