Signatures of octupole correlations in neutron-rich odd-mass barium isotopes

Abstract

Octupole deformation and the relevant spectroscopic properties of neutron-rich odd-mass barium isotopes are investigated in a theoretical framework based on nuclear density functional theory and the particle-core coupling scheme. The interacting-boson Hamiltonian that describes the octupole-deformed even-even core nucleus, as well as the single-particle energies and occupation probabilities of an unpaired nucleon, are completely determined by microscopic axially-symmetric (β2, β3)-deformation constrained self-consistent mean-field calculations for a specific choice of the energy density functional and pairing interaction. A boson-fermion interaction that involves both quadrupole and octupole degrees of freedom is introduced, and their strength parameters are determined to reproduce selected spectroscopic data for the odd-mass nuclei. The model reproduces recent experimental results both for the even-even and odd-mass Ba isotopes. In particular, for 145,147 Ba our results indicate, in agreement with recent data, that octupole deformation does not determine the structure of the lowest states in the vicinity of the ground state, and only becomes relevant at higher excitation energies.

Quadrupole and octupole collectivity in Ba143

“…IV B. In fact, recent results [49] in the framework of the sdf -Interacting Boson Model, with a mapped Hamiltonian determined from (β 2 , β 3 )-constrained self-consistent mean-field calculations, predict for 142,143 Ba a weakly deformed quadrupole shape with (β 2 , β 3 ) ≈ (0.14, 0) and B(E 3; 9 2 − → 15 2 + ) = 0.022 e 2 b 3 . The predicted B(E 3) value is quite close to the experimental upper limit, while the quadrupole deformation can be calculated from the B(E 2; 9 2 − → 5 2 − ) transition strength [50]:…”

Microscopic description of quadrupole-octupole coupling in neutron-rich actinides and superheavy nuclei with the Gogny-D1M energy density functional

“…From a theoretical point of view, various models and approaches have already been employed to study the properties of octupole collectivity. Among them we can mention the studies of octupole shapes carried out using the macroscopic-microscopic (MM) approach [19][20][21][22][23] or the use of the Interacting Boson Model (IBM) [24][25][26][27] with parameters determined using fermion-to-boson mapping procedures starting from mean-field potential energy surfaces (MFPESs), obtained with relativistic and non-relativistic energy density functionals (EDFs).…”

Octupole correlations in light actinides from the interacting boson model based on the Gogny energy density functional

“…[40,41] In this approach, the SCMF po-tential energy surfaces (SCMF-PESs) are mapped onto the corresponding (bosonic) IBM-PESs as to determine some of the strength parameters of the corresponding IBM Hamiltonian, which is subsequently used to compute excitation spectra and transition probabilities. The method has been employed to study octupole related effects like the surveys of octupole related properties in the rare-earth and actinide regions [42][43][44] or the description of octupole bands in neutron-rich odd-mass nuclei [45]. The SCMF-PESs have been computed using the relativistic DD-PC1 [46] or the non-relativistic Gogny-D1M [47,48] EDFs.…”