Spectroscopy of low-spin states in Dy157: Search for evidence of enhanced octupole correlations

Low-spin states of Dy157 have been studied using the JUROGAM II array, following the Gd155 (α, 2n) reaction at a beam energy of 25 MeV. The level scheme of Dy157 has been expanded with four new bands. Rotational structures built on the [523]5/2− and [402]3/2+ neutron orbitals constitute new additions to the level scheme as do many of the inter- and intraband transitions. This manuscript also reports the observation of cross I+→(I–1)− and I−→(I–1)+ E1 dipole transitions interlinking structures built on the [523]5/2− (band 5) and [402]3/2+ (band 7) neutron orbitals. These interlacing band structures are interpreted as the bands of parity doublets with simplex quantum number s=–i related to possible octupole correlations.