Background: For nuclei heavier than 208 Pb α decay is a dominating decay mode, and in the search of new superheavy elements one often observes chains of α decays.Purpose: Explore and test microscopic descriptions of α decay based on theories with effective nuclear interactions.Methods: The nuclear ground states are calculated with the Hartree-Fock-Bogoliubov (HFB) method using the Skyrme interaction. Microscopic α-decay formation amplitudes are calculated from the HFB wave functions, and the R-matrix formalism is utilized to obtain decay probabilities.Results: Using a large harmonic-oscillator basis we obtain converged α-decay widths. A comparison with experiment including all spherical even-even α emitting nuclei shows that the model consistently predicts too small formation amplitudes while relative values are in good agreement with experiment.
Conclusions:The method was found to be numerically practical even with a large basis size. The comparison of formation amplitudes suggests that the pairing type correlations included in the HFB approach cannot produce sufficient α-particle clustering.
Atomic spectral lines from different isotopes display a small shift in energy, commonly referred to as the line isotope shift. One of the components of the isotope shift is the field shift, which depends on the extent and the shape of the nuclear charge density distribution. The purpose of this work is to investigate how sensitive field shifts are with respect to variations in the nuclear size and shape and what information of nuclear charge distributions can be extracted from measurements. Nuclear properties are obtained from nuclear density functional theory calculations based on the Skyrme-Hartree-Fock-Bogoliubov approach. These results are combined with multiconfiguration Dirac-Hartree-Fock methods to obtain realistic field shifts and it is seen that phenomena such as nuclear deformation and variations in the diffuseness of nuclear charge distributions give measurable contributions to the isotope shifts. Using a different approach, we demonstrate the possibility to extract information concerning the nuclear charge densities from the observed field shifts. We deduce that combining methods used in atomic and nuclear structure theory gives an improved description of field shifts and that extracting additional nuclear information from measured isotope shifts is possible in the near future with improved experimental methods.
The large number of high-spin bands that have been observed in A = 56-62 nuclei are analyzed systematically within the cranked Nilsson-Strutinsky approach. Optimized Nilsson single-particle parameters are derived from investigations of energy differences between experimental and calculated rotational bands. Specifically, the relative energies of bands in neighboring nuclei whose configurations differ by having a high-j orbital either filled or empty are analyzed. The level schemes calculated with the new Nilsson parameters are compared with those using standard Nilsson parameters. Some configuration assignments are revised.
We have recently developed a series of accurately calibrated nuclear energy density functionals, fitted to essentially all atomic masses with a model root mean square deviation now reduced to 0.5 MeV for our functional BSk27*. At the same time, these functionals were adjusted to realistic equations of state of neutron matter and were constrained to reproduce various properties of nuclear matter. Using BSk27 * , we have calculated the internal constitution and the equation of state of the crust of non-accreting neutron stars.
We present the first application of a new approach, proposed in [Journal of Physics G: Nuclear and Particle Physics, vol. 43, 04LT01 (2016)] to derive coupling constants of the Skyrme energy density functional (EDF) from ab initio Hamiltonian. By perturbing the ab initio Hamiltonian with several functional generators defining the Skyrme EDF, we create a set of metadata that is then used to constrain the coupling constants of the functional. We use statistical analysis to obtain such an ab initioequivalent Skyrme EDF. We find that the resulting functional describes properties of atomic nuclei and infinite nuclear matter quite poorly. This may point out to the necessity of building up the ab initio-equivalent functionals from more sophisticated generators. However, we also indicate that the current precision of the ab initio calculations may be insufficient for deriving meaningful nuclear EDFs.
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