70 research outputs found
Computer program for the relativistic mean field description of the ground state properties of even-even axially deformed nuclei
A Fortran program for the calculation of the ground state properties of
axially deformed even-even nuclei in the relativistic framework is presented.
In this relativistic mean field (RMF) approach a set of coupled differential
equations namely the Dirac equation with potential terms for the nucleons and
the Glein-Gordon type equations with sources for the meson and the
electromagnetic fields are to be solved self-consistently. The well tested
basis expansion method is used for this purpose. Accordingly a set of harmonic
oscillator basis generated by an axially deformed potential are used in the
expansion. The solution gives the nucleon spinors, the fields and level
occupancies, which are used in the calculation of the ground state properties.Comment: 18 pages, LaTex, 6 p.s figures, To appear in Comput. Phys. Commu
Roles of proton-neutron interactions in alpha-like four-nucleon correlations
An extended pairing plus QQ force model, which has been shown to successfully
explain the nuclear binding energy and related quantities such as the symmetry
energy, is applied to study the alpha-like four-nucleon correlations in
1f_{7/2} shell nuclei.
The double difference of binding energies, which displays a characteristic
behavior at , is interpreted in terms of the alpha-like
correlations. Important roles of proton-neutron interactions forming the
alpha-like correlated structure are discussed.Comment: 10 pages, 2 figures, RevTex, submitted to Phys. Rev.
Microscopic Description of Super Heavy Nuclei
The results of extensive microscopic Relativistic Mean Field (RMF)
calculations for the nuclei appearing in the alpha - decay chains of recently
discovered superheavy elements with Z = 109 to 118 are presented and discussed.
The calculated ground state properties like total binding energies, Q values,
deformations, radii and densities closely agree with the corresponding
experimental data, where available. The double folding (t-rho-rho)
approximation is used to calculate the interaction potential between the
daughter and the alpha, using RMF densities along with the density dependent
nucleon - nucleon interaction (M3Y). This in turn, is employed within the WKB
approximation to estimate the half lives without any additional parameter for
alpha - decay. The half lives are highly sensitive to the Q values used and
qualitatively agree with the corresponding experimental values. The use of
experimental Q values in the WKB approximation improves the agreement with the
experiment, indicating that the resulting interaction potential is reliable and
can be used with confidence as the real part of the optical potential in other
scattering and reaction processes.Comment: Accepted for publication in Annals of Physics (NY
Alpha decay and proton-neutron correlations
We study the influence of proton-neutron (p-n) correlations on alpha-decay
width. It is shown from the analysis of alpha Q values that the p-n
correlations increase the penetration of the alpha particle through the Coulomb
barrier in the treatment following Gamow's formalism, and enlarges the total
alpha-decay width significantly.
In particular, the isoscalar p-n interactions play an essential role in
enlarging the alpha-decay width.
The so-called "alpha-condensate" in Z > 84 isotopes are related to the strong
p-n correlations.Comment: 5 pages, 6 figures, accepted for publication in Phys. Rev. C (R.C.
Superheavy Nuclei in the Relativistic Mean Field Theory
We have carried out a study of superheavy nuclei in the framework of the
Relativistic Mean-Field theory. Relativistic Hartree-Bogoliubov (RHB)
calculations have been performed for nuclei with large proton and neutron
numbers. A finite-range pairing force of Gogny type has been used in the RHB
calculations. The ground-state properties of very heavy nuclei with atomic
numbers Z=100-114 and neutron numbers N=154-190 have been obtained. The results
show that in addition to N=184 the neutron numbers N=160 and N=166 exhibit an
extra stability as compared to their neighbors. For the case of protons the
atomic number Z=106 is shown to demonstrate a closed-shell behavior in the
region of well deformed nuclei about N=160. The proton number Z=114 also
indicates a shell closure. Indications for a doubly magic character at Z=106
and N=160 are observed. Implications of shell closures on a possible synthesis
of superheavy nuclei are discussed.Comment: 29 pages Latex, 13 ps figures, to appear in Nucl. Phys.
Identical Bands in Superdeformed Nuclei: A Relativistic Description
Relativistic Mean Field Theory in the rotating frame is used to describe
superdeformed nuclei. Nuclear currents and the resulting spatial components of
the vector meson fields are fully taken into account. Identical bands in
neighboring Rare Earth nuclei are investigated and excellent agreement with
recent experimental data is observed.Comment: 11 pages (Latex) and 4 figures (available upon request)
TUM-ITP-Ko93/
Relativistic Hartree-Bogoliubov Approach for Nuclear Matter with Non-Linear Coupling Terms
We investigate the pairing property of nuclear matter with Relativistic
Hartree-Bogoliubov(RHB) approach. Recently, the RHB approach has been widely
applied to nuclear matter and finite nuclei. We have extended the RHB approach
to be able to include non-linear coupling terms of mesons. In this paper we
apply it to nuclear matter and observe the effect of non-linear terms on
pairing gaps.Comment: 13 pages, 5 figure
The structure of superheavy elements newly discovered in the reaction of Kr with Pb
The structure of superheavy elements newly discovered in the
Pb(Kr,n) reaction at Berkeley is systematically studied in the
Relativistic Mean Field (RMF) approach. It is shown that various usually
employed RMF forces, which give fair description of normal stable nuclei, give
quite different predictions for superheavy elements. Among the effective forces
we tested, TM1 is found to be the good candidate to describe superheavy
elements. The binding energies of the 118 nucleus and its
decay daughter nuclei obtained using TM1 agree with those of FRDM
within 2 MeV. Similar conclusion that TM1 is the good interaction is also drawn
from the calculated binding energies for Pb isotopes with the Relativistic
Continuum Hartree Bogoliubov (RCHB) theory. Using the pairing gaps obtained
from RCHB, RMF calculations with pairing and deformation are carried out for
the structure of superheavy elements. The binding energy, shape, single
particle levels, and the Q values of the decay are
discussed, and it is shown that both pairing correlation and deformation are
essential to properly understand the structure of superheavy elements. A good
agreement is obtained with experimental data on . %Especially, the
atomic number %dependence of %seems to match with the experimental
observationComment: 19 pages, 5 figure
Anatomy of nuclear shape transition in the relativistic mean field theory
A detailed microscopic study of the temperature dependence of the shapes of
some rare-earth nuclei is made in the relativistic mean field theory. Analyses
of the thermal evolution of the single-particle orbitals and their occupancies
leading to the collapse of the deformation are presented. The role of the
non-linear field on the shape transition in different nuclei is also
investigated; in its absence the shape transition is found to be sharper.Comment: REVTEX file (13pages), 12 figures, Phys. Rev. C(in press),
\documentstyle[aps,preprint]{revtex
Generator Coordinate Truncations
We investigate the accuracy of several schemes to calculate ground-state
correlation energies using the generator coordinate technique. Our test-bed for
the study is the interacting boson model, equivalent to a 6-level
Lipkin-type model. We find that the simplified projection of a triaxial
generator coordinate state using the subgroup of the rotation group is
not very accurate in the parameter space of the Hamiltonian of interest. On the
other hand, a full rotational projection of an axial generator coordinate state
gives remarkable accuracy. We also discuss the validity of the simplified
treatment using the extended Gaussian overlap approximation (top-GOA), and show
that it works reasonably well when the number of boson is four or larger.Comment: 19 pages, 6 eps figure
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