Coulomb Excitation of Rotational Levels in Dysprosium

We have investigated the Coulomb excitation of energy levels in isotopically enriched targets of dysprosium by alpha-particle bombardment. One rotational level was observed in each of the two even-even isotopes ${\mathrm{Dy}}^{162}$ and ${\mathrm{Dy}}^{164}$ with energies of 82 kev and 75 kev and transition probabilities $\epsilon B\left(E2\mathrm{}\right)\mathrm{}$ (in units of ${\mathit{e}}^2$×${10}^{-48\mathrm{}}$ ${\mathrm{cm}}^4$) equal to 1.65 and 1.09, respectively. Two rotational levels were excited in the odd-$A$ isotope ${\mathrm{Dy}}^{161}$ with energies 46 kev and 103 kev, with values of $\epsilon B\left(E2\mathrm{}\right)\mathrm{}$ equal to 2.44 and 0.04. Two rotational levels were also observed in the isotope ${\mathrm{Dy}}^{163}$ at 75 kev and 166 kev, having $\epsilon B\left(E2\mathrm{}\right)\mathrm{}$ values of 0.43 and 0.67, respectively. There is also evidence for a 93-kev gamma ray in ${\mathrm{Dy}}^{163}$ which, from coincidence measurements, appears to be the cascade transition from the second to the first excited level.