Two-quasiparticle isomers and bands ofNd154,156andSm156

μs isomers of Nd158,160

“…The 1197.1-and 892.8-keV transitions are assigned as decays directly out of 2-qp isomeric states of 158,160 Nd, respectively, giving energies for the isomeric states of (1648.1) and 1107.9 keV. These isomer level energies are close to the ones of known 2-qp isomeric states in the neighboring Nd and Sm nuclei [5][6][7].…”

“…Figures 2 and 3 show that all delayed transitions in both 158,160 Nd are observed in mutual coincidence, with the exception of the weak 65.2-keV γ ray, and form a single cascade in each nucleus. The (4 + 1 ) → (2 + 1 ) decays of the ground-state rotational bands of 152,154,156 Nd have energies of 164.2, 162.4, and 155.0 keV, respectively [3,7]. The observed 151.7-and 149.9-keV delayed γ rays are close to these energies and are therefore assigned as transitions between the (4 + 1 ) and (2 + 1 ) levels of 158,160 Nd, respectively.…”

“…Low fission yields, along with near-identical γ -ray transition energies in neighboring nuclei, limit the possibilities of studying excited states of the more neutron-rich isotopes of this chain with this technique. All known deformed, neutron-rich, even-even Nd nuclei with N > 90 possess K-isomeric states [6][7][8], which result from decays invoking large changes of the projection of the angular momentum vector on the symmetry axis. Several of the nearby N = 98 and 100 isotopes are also known to possess two-quasiparticle (2-qp) isomeric states, [7,9,10], one may therefore expect similar long-lived states to exist in 158,160 Nd.…”

“…All known deformed, neutron-rich, even-even Nd nuclei with N > 90 possess K-isomeric states [6][7][8], which result from decays invoking large changes of the projection of the angular momentum vector on the symmetry axis. Several of the nearby N = 98 and 100 isotopes are also known to possess two-quasiparticle (2-qp) isomeric states, [7,9,10], one may therefore expect similar long-lived states to exist in 158,160 Nd. The presence of isomeric states offers the opportunity to study the structure of these nuclei via the use of delayed γ -ray spectroscopy of in-flight, mass-separated beams of fission fragments.…”

“…From N = 92 onwards their quadrupole deformation is close to saturation and these nuclei possess well-deformed * simpson@lpsc.in2p3.fr prolate ground-state rotational bands, as evidenced by their E(4 + )/E(2 + ) ratios of ∼3.3 [2]. The isotopes [152][153][154][155][156] Nd have exactly these properties [3][4][5] and the latter is the most neutron-rich Nd isotope with known excited states [4,6,7]. This nucleus was studied using spontaneous fission sources placed at the center of large arrays of Ge detectors.…”