Study of the Decay ofTm168to Levels inEr168Using Coincidence and Directional Correlation Techniques

The levels in ${\mathrm{Er}}^{168}$ populated by electron capture of ${\mathrm{Tm}}^{168}$ have been studied using scintillation spectrometers, gamma-gamma and electron-gamma coincidence measurements, and directional correlation techniques. This work leads to the following conclusions: the spin and parity of the 1543-keV level are verified as 3-; the 1280-keV transition is $E1(<~0.08\%M2)$; the 721-keV transition is $E1(<~0.05\%M2)$; and the 743-keV transition is $E2(<~2.4\%M1)$. The attenuation coefficient ${\overline{G}}_2$ for the 1280-80-keV correlation was determined to be 0.77±0.19 for a source consisting of a dilute aqueous solution of Tm${\mathrm{Cl}}_3$. The analysis of the results of the ${\mathrm{Tm}}^{168}$ decay is compared with the predictions using various models. The ratios of reduced transition probabilities for transitions from the gamma vibrational band in ${\mathrm{Er}}^{168}$ are analyzed and a bandmixing parameter $z=0.055\mathrm{}$ is found.