66 research outputs found
Gamow-Teller response and its spreading mechanism in doubly magic nuclei
The scope of the paper is to apply a state-of-the-art beyond mean-field model
to the description of the Gamow-Teller response in atomic nuclei. This topic
recently attracted considerable renewed interest, due, in particular, to the
possibility of performing experiments in unstable nuclei. We study the cases of
Ca, Ni, Sn and Pb. Our model is based on a fully
self-consistent Skyrme Hartree-Fock plus random phase approximation. The same
Skyrme interaction is used to calculate the coupling between particles and
vibrations, which leads to the mixing of the Gamow-Teller resonance with a set
of doorway states and to its fragmentation. We compare our results with
available experimental data. The microscopic coupling mechanism is also
discussed in some detail.Comment: 27 pages, 10 figure
Stellar electron-capture rates calculated with the finite-temperature relativistic random-phase approximation
We introduce a self-consistent microscopic theoretical framework for
modelling the process of electron capture on nuclei in stellar environment,
based on relativistic energy density functionals. The finite-temperature
relativistic mean-field model is used to calculate the single-nucleon basis and
the occupation factors in a target nucleus, and , ,
charge-exchange transitions are described by the self-consistent
finite-temperature relativistic random-phase approximation. Cross sections and
rates are calculated for electron capture on 54,56Fe and 76,78Ge in stellar
environment, and results compared with predictions of similar and complementary
model calculations.Comment: Physical Review C, accepte
-decay half-lives as an indicator of shape-phase transition in neutron-rich Zr isotopes with particle-vibration coupling effect
[Background] -decay half-life is sensitive to the shell structure near
the Fermi levels. Nuclear deformation thus impacts the -decay
properties. [Purpose] A first-order shape-phase transition in neutron-rich Zr
isotopes is predicted by some models. We investigate the -decay
half-lives of neutron-rich nuclei around Zr, where the shape-phase
transition is predicted to occur, to see if the -decay half-life can be
an indicator of the shape changes. [Method] The proton-neutron quasiparticle
random-phase approximation (RPA) is adopted to calculate the Gamow-Teller
transitions. In addition, we apply the quasiparticle phonon-vibrational
coupling (PVC) to consider the phonon couplings. [Results] The spherical and
oblate configurations give similar half-lives but shorter ones than the prolate
configuration at the RPA level. The PVC effect further reduces the half-lives
in general, but the effect is smaller for the deformed configuration than that
for the spherical one. As a result, it makes the shape change from the oblate
configuration to the spherical configuration visible. Therefore, a sudden
shortening of -decay half-lives is always found at the nuclear shape
changes. [Conclusions] -decay half-life is an indicator of the
shape-phase transition. The shape mixing and the roles of the triaxial
deformation are subject to study in the future.Comment: 7 pages, 4 figure
The Gamow-Teller response within Skyrme random-phase approximation plus particle-vibration coupling
Although many random-phase approximation (RPA) calculations of the
Gamow-Teller (GT) response exist, this is not the case for calculations going
beyond the mean-field approximation. We apply a consistent model that includes
the coupling of the GT resonance to low-lying vibrations, to nuclei of the
shell. Among other motivations, our goal is to see if the particle-vibration
coupling can redistribute the low-lying GT strength that is relevant for
electron-capture processes in core-collapse supernova. We conclude that the
lowering and fragmentation of that strength are consistent with the
experimental findings and validate our model. However, the particle-vibration
coupling cannot account for the quenching of the total value of the low-lying
strength.Comment: 25 pages, 10 figure
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