468 research outputs found
Nuclear Liquid Drop Model with the Surface-Curvature Terms: New Perspectives for the Hyperdeformation Studies
Nuclear liquid drop model is revisited and an explicit introduction of the
surface-curvature terms is presented. The corresponding parameters of the
extended classical energy formula are adjusted to the contemporarily known
nuclear binding energies and fission barrier heights. Using 2766 binding
energies of nuclei with and it is shown that the
performance of the new approach is improved by a factor of about 6, compared to
the previously published liquid drop model results, in terms of both the masses
(new r.m.s. deviation MeV) and the fission barriers (new
r.m.s. deviation of the fission barriers of isotopes with is MeV).
The role of the curvature terms and their effects on the description of the
experimental quantities are discussed in detail; for comparison the parameters
of the more 'traditional' approaches are re-fitted taking into account the
nuclear masses known today and the performances of several variants of the
model are compared. The isospin dependence in the new description of the
barriers is in a good agreement with the extended Thomas-Fermi approach; it
also demonstrates a good qualitative agreement with the fission life-time
systematics tested on the long chain of Fermium isotopes known experimentally.
The new approach offers also a very high stability in terms of the
extrapolation from the narrower range of nuclides to a more extended one - a
property of particular interest for the contemporary exotic beam projects: the
corresponding properties are illustrated and discussed.Comment: 25 pages in LaTeX and 20 figures in eps forma
Shell Structure of Cesium Layer Covering the C60 Fullerene Core
Strutinsky shell corrections for the Cesium-coated fullerenes were
investigated. The single particle levels of electrons are obtained using the
spherical mean-field potential of a shifted Wood-Saxon type. The parameters of
the potential are adjusted to reproduce the experimental ionization energies of
the Cs(N) clusters and the magic numbers observed in their photo-ionization
spectra of the C60Cs(N) aggregates.Comment: 6 pages in LaTex, 7 eps figure
Fission-Fragment Mass Distribution and Particle Evaporation at low Energies
Fusion-fission dynamics is investigated with a special emphasis on fusion
reactions at low energy for which shell effects and pairing correlations can
play a crucial role leading in particular to multi-modal fission. To follow the
dynamical evolution of an excited and rotating nucleus we solve a 2-dimensional
Langevin equation taking explicitly light-particle evaporation into account.
The confrontation theory-experiment is demonstrated to give interesting
information on the model presented, its qualities as well as its shortcomings.Comment: 19 pages, latex, 24 eps-figure
Mean-Field Description of Fusion Barriers with Skyrme's Interaction
Fusion barriers are determined in the framework of the Skyrme energy-density
functional together with the semi-classical approach known as the Extended
Thomas-Fermi method. The barriers obtained in this way with the Skyrme
interaction SkM* turn out to be close to those generated by phenomenological
models like those using the proximity potentials. It is also shown that the
location and the structure of the fusion barrier in the vicinity of its maximum
and beyond can be quite accurately described by a simple analytical form
depending only on the masses and the relative isospin of target and projectile
nucleus.Comment: 7 pages, latex, 5 figure
Selfconsistent calculations of fission barriers in the Fm region
The fission barriers of the nuclei 254Fm, 256Fm, 258Fm, 258No and 260Rf are
investigated in a fully microscopic way up to the scission point. The analysis
is based on the constrained Hartree-Fock-Bogoliubov theory and Gogny's D1S
force. The quadrupole, octupole and hexadecapole moments as well as the number
of nucleons in the neck region are used as constraints. Two fission paths,
corresponding to the bimodal fission, are found. The decrease with isotope mass
of the half-life times of heavy Fm isotopes is also explained.Comment: 29 pages in LaTeX including 14 figure
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