90 research outputs found
Isospin Dependence of Proton and Neutron Radii within Relativistic Mean Field Theory
The binding energies, shapes and sizes of even-even beta-stable nuclei with A
>= 40 and a few chains of isotopes with Z=50, 56, 82, 94 protons and isotones
with N=50, 82, 126 neutrons are analyzed. The average isospin dependence of the
radii of protons and neutrons evaluated within the relativistic mean field
theory is studied. A simple, phenomenological formula for neutron radii is
proposed.Comment: 10 pages in Latex and 14 figures in the eps forma
Simple Formula for Nuclear Charge Radius
A new formula for the nuclear charge radius is proposed, dependent on the
mass number (A) and neutron excess (N-Z) in the nucleus. It is simple and it
reproduces all the experimentally available mean square radii and their
isotopic shifts of even--even nuclei much better than other frequently used
relations.Comment: The paper contains 7 pages in LateX and 6 figures (available upon
request) in postscript. Email: [email protected]
Interaction Strengths for the Fock-Space Formulation of the Nuclear Pairing Problem
A realistic nuclear mean-field hamiltonian with pairing has been diagonalized
using Fock space representation that allows for nearly exact treatment of the
problem. Calculations were performed for all the even-even nuclei with Z in
(20, 100), whose pairing gaps were possible to extract out of the experimental
masses. The optimal values of the pairing strength constants for the protons
and neutrons have been found.Comment: Seminar given at XXXVII School of Physics in Zakopane, Poland. Paper
in LaTeX, 4 pages including one figure, submitted to Acta Physica Polonica
Global Properties of Spherical Nuclei Obtained from Hartree-Fock-Bogoliubov Calculations with the Gogny Force
Selfconsistent Hartree-Fock-Bogoliubov (HFB) calculations have been performed
with the Gogny force for nuclei along several constant Z and constant N chains,
with the purpose of extracting the macroscopic part of the binding energy using
the Strutinsky prescription. The macroscopic energy obtained in this way is
compared to current liquid drop formulas. The evolution of the single particle
levels derived from the HFB calculations along the constant Z and constant N
chains and the variations of the different kinds of nuclear radii are also
analysed. Those radii are shown to follow isospin-dependent three parameter
laws close to the phenomenological formulas which reproduce experimental data.Comment: 17 pages in LaTeX and 17 figures in eps. Phys. Rev. C, accepted for
publicatio
Ground state properties of the stable nuclei in various mean field theories
The separation energies of neutrons and protons, binding energies, mean
square charge radii, electric quadrupole moments and deformation parameters of
the proton and neutron distributions are evaluated for stable even-even
nuclei with . We compare the theoretical estimates obtained
within the Hartree-Fock plus BCS model with a few sets of Skyrme forces,
relativistic mean-field theory and frequently used Saxon-Woods and Nilsson
potentials with experimental data.Comment: 15 pages, latex, 3 tables, 14 figures in thr eps format include
Parametrizations of triaxial deformation and E2 transitions of the wobbling band
By the very definition the triaxial deformation parameter is related
to the expectation values of the K=0 and K=2 components of the intrinsic
quadrupole tensor operator. On the other hand, using the same symbol
"", various different parametrizations of triaxial deformation have
been employed, which are suitable for various types of the mean-field
potentials. It is pointed out that the values of various "" are quite
different for the same actual triaxial deformation, especially for the large
deformation; for example, the difference can be almost a factor two for the
case of the triaxial superdeformed bands recently observed in the Hf and Lu
nuclei. In our previous work, we have studied the wobbling band in Lu nuclei by
using the microscopic framework of the cranked Nilsson mean-field and the
random phase approximation, where the most serious problem is that the
calculated B(E2) value is about factor two smaller. It is shown that the origin
of this underestimation can be mainly attributed to the small triaxial
deformation; if is used the same triaxial deformation as in the analysis of the
particle-rotor model, the calculated B(E2) increases and gives correct
magnitude compared with the experimental data.Comment: 10 pages, 9 figure
Effect of differences in proton and neutron density distributions on fission barriers
The neutron and proton density distributions obtained in constrained
Hartree-Fock-Bogolyubov calculations with the Gogny force along the fission
paths of 232Th, 236U, 238U and 240Pu are analyzed.
Significant differences in the multipole deformations of neutron and proton
densities are found. The effect on potential energy surfaces and on barrier
heights of an additional constraint imposing similar spatial distributions to
neutrons and protons, as assumed in macroscopic-microscopic models, is studied.Comment: 5 pages in Latex, 4 figures in ep
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