Spectroscopy of odd-odd nuclei within the interacting boson-fermion-fermion model based on the Gogny energy-density functional

Abstract

We present a method to calculate spectroscopic properties of odd-odd nuclei within the framework of the Interacting Boson-Fermion-Fermion Model based on the Gogny energy density functional. The (β, γ)-deformation energy surface of the even-even (boson-)core nucleus, spherical single-particle energies and occupation probabilities of the odd neutron and odd proton, are provided by the constrained self-consistent mean-field calculation within the Hartree-Fock-Bogoliubov method with the Gogny-D1M functional. These quantities are used as a microscopic input to fix most of the parameters of the IBFFM Hamiltonian. Only a few coupling constants for the boson-fermion Hamiltonian and the residual neutron-proton interaction are specifically adjusted to reproduce experimental low-energy spectra in odd-mass and odd-odd nuclei, respectively. In this way, the number of free parameters involved in the IBFFM framework is reduced significantly. The method is successfully applied to the description of the low-energy spectra and electromagnetic transition rates in the odd-odd 194,196,198 Au nuclei.

β decay of odd- A nuclei with the interacting boson-fermion model based on the Gogny energy density functional

“…Three coupling constants for the boson-fermion interaction terms are determined so as to reproduce reasonably well the experimental low-energy spectrum in a given odd-A system. At the cost of having to determine these few coupling constants empirically, the method allows a detailed and simultaneous description of spectroscopy in even-even, odd-A, and odd-odd nuclei [33].…”

Structure of odd-odd Cs isotopes within the interacting boson-fermion-fermion model based on the Gogny-D1M energy density functional

“…The IBFFM represents a further extension of the IBFM to odd-odd systems that includes, one unpaired neutron and one unpaired proton [14,15]. As in our previous study for oddodd Au isotopes [8], we have used a version of the IBFFM that distinguishes between neutron and proton degrees of freedom (denoted hereafter as IBFFM-2). The IBFFM-2 Hamiltonian reads…”

“…Using the wave functions obtained after the diagonalization of the IBFFM-2 Hamiltonian, the electric quadrupole (E2) and magnetic dipole (M1) properties can be computed. The corresponding T (E2) and T (M 1) operators are given by [8]…”

“…To overcome these difficulties we proposed in Ref. [8] (in a study of odd-A Au and Pt and odd-odd Au isotopes) to perform constrained Hartree-Fock-Bogoliubov (HFB) calculations based on the Gogny [9] energy density functional (EDF) with the parametrization D1M [10], to obtain energy surfaces as functions of the (β, γ) quadrupole deformation parameters for the neighboring even-even Pt nuclei. The single-particle energies and occupation numbers were computed for the odd neutron and odd proton in the odd-mass Au and Pt as well as odd-odd Au isotopes.…”

“…In this work, we consider the spectroscopic properties of the odd-odd nuclei 124−132 Cs, using the theoretical framework developed in Ref. [8]. The reason for the choice of nuclei is that the A ≈130 mass region exhibits a wide variety of structural phenomena.…”