Two-quasiparticle isomers and bands of Nd154,156 and Sm156,158,160

Abstract

The decay of a new 3.2-μs, (4-) isomeric state at 1298.0 keV has been observed using γ-ray spectroscopy at the Lohengrin mass spectrometer of the Institut Laue-Langevin. By comparison with theoretical calculations this state was assigned a ν5/2[642]ν3/2[521] dominant configuration. Prompt γ-ray data from a spontaneous fission experiment have also been analyzed allowing the observation of a collective band on top of this isomeric state, the identification of a new band on top of the previously reported (5-) isomer of Nd156 and the extension of collective bands on top of (5-) isomers of the neighboring Sm156,158 nuclei. Quasiparticle rotor model calculations reported in this work correctly predict the energies and decay patterns of these bands. A new (5-) isomer in Sm160 has also been observed. The calculations predict ν5/2[642]ν5/2[523] dominant configurations for all these (5-) isomers. © 2009 The American Physical Society.