588 research outputs found
Cluster radioactivity in Ba in the HFB theory
Cluster radioactivity in Ba is described as a spontaneous fission
with a large mass asymmetry within the self-consistent HFB theory. A new
fission valley with large octupole deformation is found in the potential energy
surface. The fragment mass asymmetry of this fission mode corresponds to the
expected one in cluster radioactivity with the emission of O predicted
with a very long half-life.Comment: 4 pages, 3 figures, Accepted for publication in Acta Physica Polonica
B, Presented at Zakopane Conference on Nuclear Physic
Cluster radioactivity of Th isotopes in the mean-field HFB theory
Cluster radioactivity is described as a very mass asymmetric fission process.
The reflection symmetry breaking octupole moment has been used in a mean field
HFB theory as leading coordinate instead of the quadrupole moment usually used
in standard fission calculations. The procedure has been applied to the study
of the ``very mass asymmetric fission barrier'' of several even-even Thorium
isotopes. The masses of the emitted clusters as well as the corresponding
half-lives have been evaluated on those cases where experimental data exist.Comment: Contribution to XIV Nuclear Physics Workshop at Kazimierz Dolny,
Poland, Sept. 26-29, 200
Density dependence of the symmetry energy from neutron skin thickness in finite nuclei
The density dependence of the symmetry energy around saturation density,
characterized by the slope parameter L, is studied using information provided
by the neutron skin thickness in finite nuclei. An estimate for L is obtained
from experimental data on neutron skins extracted from antiprotonic atoms. We
also discuss the ability of parity-violating elastic electron scattering to
obtain information on the neutron skin thickness in 208Pb and to constrain the
density dependence of the nuclear symmetry energy. The size and shape of the
neutron density distribution of 208Pb predicted by mean-field models is briefly
addressed. We conclude with a comparative overview of the L values predicted by
several existing determinations.Comment: 17 pages, 10 figures, submitted to EPJA special volume on Nuclear
Symmetry Energ
Nuclear symmetry energy and neutron skin thickness
The relation between the slope of the nuclear symmetry energy at saturation
density and the neutron skin thickness is investigated. Constraints on the
slope of the symmetry energy are deduced from the neutron skin data obtained in
experiments with antiprotonic atoms. Two types of neutron skin are
distinguished: the "surface" and the "bulk". A combination of both types forms
neutron skin in most of nuclei. A prescription to calculate neutron skin
thickness and the slope of symmetry energy parameter from the parity
violating asymmetry measured in the PREX experiment is proposed.Comment: 12 pages, 5 figures, Presented at XXXII Mazurian Lakes Conference on
Physics, Piaski, Poland, September 11-18, 201
Influence of the single-particle structure on the nuclear surface and the neutron skin
We analyze the influence of the single-particle structure on the neutron
density distribution and the neutron skin in Ca, Ni, Zr, Sn, and Pb isotopes.
The nucleon density distributions are calculated in the Hartree-Fock+BCS
approach with the SLy4 Skyrme force. A close correlation is found between the
quantum numbers of the valence neutrons and the changes in the position and the
diffuseness of the nuclear surface, which in turn affect the neutron skin
thickness. Neutrons in the valence orbitals with low principal quantum number
and high angular momentum mainly displace the position of the neutron surface
outwards, while neutrons with high principal quantum number and low angular
momentum basically increase the diffuseness of the neutron surface. The impact
of the valence shell neutrons on the tail of the neutron density distribution
is discussed.Comment: 17 pages, 14 figure
Calculations of giant magnetoresistance in Fe/Cr trilayers using layer potentials determined from {\it ab-initio} methods
The ab initio full-potential linearized augmented plane-wave method
explicitly designed for the slab geometry was employed to elucidate the
physical origin of the layer potentials for the trilayers nFe/3Cr/nFe(001),
where n is the number of Fe monolayers. The thickness of the transition-metal
ferromagnet has been ranged from up to n=8 while the spacer thickness was
fixed to 3 monolayers. The calculated potentials were inserted in the
Fuchs-Sondheimer formalism in order to calculate the giant magnetoresistance
(GMR) ratio. The predicted GMR ratio was compared with the experiment and the
oscillatory behavior of the GMR as a function of the ferromagnetic layer
thickness was discussed in the context of the layer potentials. The reported
results confirm that the interface monolayers play a dominant role in the
intrinsic GMR.Comment: 17 pages, 7 figures, 3 tables. accepted in J. Phys.: Cond. Matte
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