Structure of the low-lying intrinsic states inEu156

Abstract

Microscopic structures of the low-lying nonrotational (intrinsic) states in the odd-odd nucleus '63Eu93 are investigated using the quasiparticle-phonon nuclear model Hamiltonian including the pairing, quadrupole-quadrupole, octupole-octupole, and residual p-n interactions. The extent of vibrational admixtures to the two-quasiparticle configurations and the intrinsic matrix elements of electric octupole operator for the "same I( opposite parity" bands are examined to conclude that, contrary to some recent suggestions, the low-energy "Eu spectrum does not contain "parity doublets" characteristic of reflection asymmetric shapes, in contrast with the structures seen in " Eu and " Eu.PACS number(s): 21.60.Ev, 27.70.+ q

Level structures in the odd–odd nucleus154Pm

“…This dilemma may be resolved by recalling that all these nine levels located within the 860 keV energy range and with J = 1 assignment (from log ft 5.6) can have rather strong K = 0 band mixing. As shown in the microscopic structure investigations of isotonic 156 Eu levels [16], there is also significant admixture between 1 + and 1 − intrinsic structures arising from octupole correlations. Ignoring this now, we find that the γ transitions from the 831.6, 850.2 and 1049.6 keV levels are very similar.…”

“…Taken together with the updated 153 Pm level structures [12], this enables a reliable mapping of the configuration space around the 154 Pm Fermi surface and the identification of physically admissible 2qp intrinsic structures in this nucleus. Furthermore, a detailed microscopic analysis [16] of low-lying 2qp excitations in the isotonic odd-odd neighbour 156 Eu, and the experimental data on the inter-band and intra-band level spacings therein [17], provide valuable inputs for more credible model calculations. Recently, we have reported [18] on the characterization of the very similar isomers in the isotopic oddodd neighbour 156 Pm, and the level spacings in the yrast band therein [19].…”