ALONSO ALONSO , Clara Eugenia

Low-lying energy states of the 147 -153Pm isotopic chain are studied within the framework of the neutron-proton interacting boson-fermion model (IBFM-2). The spectra of these isotopes show a transition from a particle coupled to a vibrational core to a particle coupled to a deformed one. The calculation reproduces this behavior. In addition,...

We investigate phase transitions in boson-fermion systems. We propose an analytically solvable model [E(5/12)] to describe odd nuclei at the critical point in the transition from the spherical to γ-unstable behavior. In the model, a boson core described within the Bohr Hamiltonian interacts with an unpaired particle assumed to be moving in the...

The mapping of the single fermion creation operator (ci†) onto the Interacting Boson-Fermion space (IBFM) is revisited within the Generalized Seniority scheme. In the original work the Number Operator Approximation (NOA) was used. Here the exact evaluation of the relevant terms using exact values for the fermion matrix elements in the...

We investigate the evolution of one-particle spectroscopic intensities as a possible signature of shape phase transitions. The study describes the odd systems in terms of the interacting boson–fermion model. We consider the particular case of an odd j=3/2 particle coupled to an even-even boson core that undergoes a phase...

We analyze the nuclear structure information obtained from measurements of charge radii in even-even and even-odd nuclei terms of the interacting boson model. The observed deviations from the smooth behavior, R = R0A1 3, appear to be well described by this model.

We carry out an interacting boson model study of the Ru isotopes using a U(5)-SO(6) transitional Hamiltonian with fixed parameters, where the variation is due only to the change in boson number N. Transitional behavior in 104Ru is compared with recent predictions of an E(5) critical symmetry, including a modified version with an...

The phase transition in odd nuclei when the underlying even-even core nuclei experience a transition from spherical to deformed γ-unstable shapes is investigated. The odd particle is assumed to be moving in the three single-particle orbitals j=1/2,3/2, and 5/2. At the critical point in the phase transition, an analytic solution to the...

The boson-conserving one-nucleon transfer operator in the interacting boson model (IBM) is reanalyzed. Extra terms are added to the usual form used for that operator. These new terms change generalized seniority by one unit, as the ones considered up to now. The results obtained using the new form for the transfer operator are...

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We present systematic calculations on nuclei in the region around A=190 within the framework of the proton-neutron interacting boson-fermion model. Energy levels and electromagnetic properties of both positive and negative parity states in odd proton (77Ir,79Au) and odd neutron (78Pt) nuclei are compared with experimental data. A general good...

The appropriate use of the interacting boson-fermion model one nucleon transfer operator in connection with nuclear supersymmetries is discussed. We emphasize that care must be taken in using the same coupling order, either l-s or s-l, in the odd particle creation operator appearing in the one nucleon transfer ...

We investigate the phase transition in odd nuclei within the Interacting Boson Fermion Model in correspondence with the transition from spherical to stable axially deformed shape. The odd particle is assumed to be moving in the single-particle orbitals with angular momenta j=1/2,3/2,5/2 with a boson-fermion Hamiltonian that leads to the...

In a recent work [arXiv:1510.03185] the use of the Transformed Harmonic Oscillator (THO) basis for the discretization of the singleparticle continuum into a Generalized Bardeen-Cooper-Schrieffer (BCS) formalism was proposed for the description of weakly bound nuclei. We make use of the flexibility of this formalism to study the evolution of the...

β -decay rates of 121–131 Cs have been calculated in the framework of the neutron-proton interacting boson- fermion model (IBFM-2). For odd- A nuclei, the decay operator can be written in a relatively simple form in terms of the one-nucleon transfer operator. Previous studies of β decay in IBFM-2 were based on a transfer operator obtained by...

We investigate different aspects connected with shape phase transitions in nuclei and the possible occurrence of dynamical symmetries at the critical points. We discuss in particular the behaviour of the neighbour odd nuclei at the vicinity of the critical points in the even nuclei. We consider both the case of the transition from the...

We investigate shape phase transitions in odd nuclei within the Interacting Boson Fermion Model. Special attention is given to the case of the transition from the vibrational behaviour to the stable axial deformation. The odd particle is assumed to be moving in the three single particle orbitals j=l/2,3/2,5/2 with a boson-fermion Hamiltonian...

Several aspect of shape phase transitions and critical point symmstries are reviewed inthis contribution within the frameworks of the Interacting Boson Model(IBM) and theInteracting Boson Fermion Model(IBFM) for even and odd sysstems respectively andcompared with collective geometric models. We discuss in particular the case of an...

The formalism of the neutron-photon interacting boson model, extended to include two-quasiparticle excitations, is used in a study of the high spin states of 154,156,158Dy isotropes. Good agreement is obtained between the calculated energies and transition rates and the experimental results.

We present results of a calculation of properties of low-lying collective quadrupole states in odd-even nuclei within the framework of the proton-neutron interacting boson-fermion model.

The Bardeen-Cooper-Schrieffer (BCS) formalism is extended by including the single-particle continuum in order to analyse the evolution of pairing in an isotopic chain from stability up to the drip line. We propose a continuum discret ized generalized BCS based on single-particle pseudostates (PS). These PS are generated from the diagonalization...

Various aspects of shape phase transitions in even as well as odd systems are reviewed. Firstly, the case of an odd j 3/2 particle coupled to an even-even boson core that undergoes a transition from spherical limit (U(5)) to the γ-unstable limit (0(6)) is illustrated. Energy spectrum and electromagnetic transitions, in correspondence of the...

The phase transition around the critical point in the evolution from spherical to deformed γ-unstable shapes is investigated in odd nuclei within the interacting boson fermion model. We consider the particular case of an odd j=3/2 particle coupled to an even-even boson core that undergoes a transition from spherical U(5) to γ-unstable O(6)...

Quadrupole moments and E2 transitions in the O(6) limit of the interacting boson model are studied within a formalism based on the intrinsic frame. We show that the values of these quantities for both ground- and β-bands can be directly obtained, to higher order in N, by suitably projecting the corresponding matrix elements associated with the...