Electromagnetic properties of the rotationally aligned band in ¹⁶²Dy

Rotational band structures in ^162,164Dy were studied by projectile inelastic excitation on a ¹¹⁸Sn target at near-barrier energies. States with spin up to 24⁺(22⁺) of the ground-state band and 18⁺(18⁺) of the γ-vibrational band in ¹⁶²Dy(¹⁶⁴Dy) were populated in these reactions. States with spin spanning from 8⁺ to 20⁺ of the rotationally aligned S band in ¹⁶²Dy were populated by way of its band-crossing point with the γ-vibrational band at spin 12⁺, where strong mixing occurred due to an accidental degeneracy. This S band eventually crosses the ground-state band at spin 18⁺ and becomes the yrast at spin 20⁺. From the peripheral-collision γ-ray yield data, sets of electromagnetic matrix elements for both the intraband and interband transitions were determined by using the Coulomb excitation code, GOSIA. The measured intraband E2 matrix elements were used to derive a quadrupole deformation of the S band that is ≈20% larger than those of the nearby low-lying collective bands. This represents the first measurement made for the quadrupole deformation of the S band for states well below the crossing point with the ground-state band. The two-phonon γ-vibration harmonic strength in ¹⁶²Dy is highly fragmented, 36% of the strength is located in two K^π=4⁺ bands at excitation energies 1535.9 and 2181.0 keV, respectively. Significant octupole collectivity was observed coupling the ground-state band to the K^π=2^- band in ¹⁶²Dy.