Study of Coriolis-decoupled bands in 155, 157, 159Dy and 155, 157, 159Er using (α, xnγ) reactions

Levels in ^{155, 157, 159}Dy and in ^{155, 157, 159}Er have been populated using (α, xnγ) reactions where x = 5, 7 or 9. The resulting γ-rays have been investigated using in-beam y-spectroscopic techniques. Mixed positive-parity bands were predominantly populated and are identified with the Coriolis-deeoupled bands described in the framework of the rotation-alignment model of Stephens and coworkers. In the case of ¹⁵⁷Dy the band was observed up to the $\text{49}\text{2}$⁺ state. The absence of the backbending effect in these nuclei can be explained by the blocking of certain $\text{13}\text{2}$ neutron orbitals near the Fermi surface which are essential for the development of the baekbending mechanism.