127 research outputs found
Analytical relationship for the cranking inertia
The wave function of a spheroidal harmonic oscillator without spin-orbit
interaction is expressed in terms of associated Laguerre and Hermite
polynomials. The pairing gap and Fermi energy are found by solving the BCS
system of two equations. Analytical relationships for the matrix elements of
inertia are obtained function of the main quantum numbers and potential
derivative. They may be used to test complex computer codes one should develop
in a realistic approach of the fission dynamics. The results given for the
Pu nucleus are compared with a hydrodynamical model. The importance of
taking into account the correction term due to the variation of the occupation
number is stressed.Comment: 12 pages, 4 figure
Shell Structure of the Superheavy Elements
Ground state properties of the superheavy elements (SHE) with Z from 108 to
128 and N from 150 to 192 are investigated using both the Skyrme-Hartree-Fock
method with a density-independent contact pairing interaction and the
macroscopic-microscopic approach with an average Woods-Saxon potential and a
monopole pairing interaction. Detailed analysis of binding energies, separation
energies, shell effects, single proton and neutron states, equilibrium
deformations, alpha-decay energies, and other observables is given.Comment: 27 RevTeX pages, 22 figures available upon request to
[email protected]
Magic numbers for superheavy nuclei in relativistic continuum Hartree-Bogoliubov theory
The magic proton and neutron numbers are searched in the superheavy region
with proton number =100 - 140 and neutron number = (+30) - (2+32)
by the relativistic continuum Hartree-Bogoliubov (RCHB) theory with
interactions NL1, NL3, NLSH, TM1, TW99, DD-ME1, PK1, and PK1R. Based on the
two-nucleon separation energies and , the two-nucleon gaps
and , the shell correction energies
and , the pairing energies and ,
and the pairing gaps and , =120, 132, and 138 and
=172, 184, 198, 228, 238, and 258 are suggested to be the magic numbers
within the present approach. The -decay half-lives are also discussed.
In addition, the potential energy surfaces of possible doubly magic nuclei are
obtained by the deformation-constrained relativistic mean field (RMF) theory,
and the shell effects stabilizing the nuclei are investigated. Furthermore, the
formation cross sections of 120 and 120 at the
optimal excitation energy are estimated by a phenomenological cold fusion
reactions model with the structure information extracted from the constrained
RMF calculation.Comment: 37 pages, 14 figure
New Outlook on the Possible Existence of Superheavy Elements in Nature
A consistent interpretation is given to some previously unexplained phenomena
seen in nature in terms of the recently discovered long-lived high spin super-
and hyper-deformed isomeric states. The Po halos seen in mica are interpreted
as due to the existence of such isomeric states in corresponding Po or nearby
nuclei which eventually decay by gamma- or beta-decay to the ground states of
210Po, 214Po and 218Po nuclei. The low-energy 4.5 MeV alpha-particle group
observed in several minerals is interpreted as due to a very enhanced alpha
transition from the third minimum of the potential-energy surface in a
superheavy nucleus with atomic number Z=108 (Hs) and atomic mass number around
271 to the corresponding minimum in the daughter.Comment: 8 pages, 8 figures, 5 tables. Paper presented at VII Int.
School-Seminar on Heavy Ion Physics, May 27 - June 1, 2002, Dubna, Russi
Fusion cross sections for superheavy nuclei in the dinuclear system concept
Using the dinuclear system concept we present calculations of production
cross sections for the heaviest nuclei. The obtained results are in a good
agreement with the experimental data. The experimentally observed rapid
fall-off of the cross sections of the cold fusion with increasing charge number
of the compound nucleus is explained. Optimal experimental conditions for
the synthesis of the superheavy nuclei are suggested.Comment: 16 pages, LaTeX, including 3 postscript figure
Fission barriers and asymmetric ground states in the relativistic mean field theory
The symmetric and asymmetric fission path for 240Pu, 232Th, and 226Ra is
investigated within the relativistic mean field model. Standard
parametrizations which are well fitted to nuclear ground state properties are
found to deliver reasonable qualitative and quantitative features of fission,
comparable to similar nonrelativstic calculations. Furthermore, stable octupole
deformations in the ground states of Radium isotopes are investigated. They are
found in a series of isotopes, qualitatively in agreement with nonrelativistic
models. But the quantitative details differ amongst the models and between the
various relativsitic parametrizations.Comment: 30 pages RevTeX, 7 tables, 12 low resolution Gif figures (high
resolution PostScript versions are available at
http://www.th.physik.uni-frankfurt.de/~bender/nucl_struct_publications.html
or at ftp://th.physik.uni-frankfurt.de/pub/bender
Shell structure of superheavy nuclei in self-consistent mean-field models
We study the extrapolation of nuclear shell structure to the region of
superheavy nuclei in self-consistent mean-field models -- the
Skyrme-Hartree-Fock approach and the relativistic mean-field model -- using a
large number of parameterizations. Results obtained with the Folded-Yukawa
potential are shown for comparison. We focus on differences in the isospin
dependence of the spin-orbit interaction and the effective mass between the
models and their influence on single-particle spectra. While all relativistic
models give a reasonable description of spin-orbit splittings, all
non-relativistic models show a wrong trend with mass number. The spin-orbit
splitting of heavy nuclei might be overestimated by 40%-80%. Spherical
doubly-magic superheavy nuclei are found at (Z=114,N=184), (Z=120,N=172) or
(Z=126,N=184) depending on the parameterization. The Z=114 proton shell
closure, which is related to a large spin-orbit splitting of proton 2f states,
is predicted only by forces which by far overestimate the proton spin-orbit
splitting in Pb208. The Z=120 and N=172 shell closures predicted by the
relativistic models and some Skyrme interactions are found to be related to a
central depression of the nuclear density distribution. This effect cannot
appear in macroscopic-microscopic models which have a limited freedom for the
density distribution only. In summary, our findings give a strong argument for
(Z=120,N=172) to be the next spherical doubly-magic superheavy nucleus.Comment: 22 pages REVTeX, 16 eps figures, accepted for publication in Phys.
Rev.
Mean-field description of ground-state properties of drip-line nuclei. (I) Shell-correction method
A shell-correction method is applied to nuclei far from the beta stability
line and its suitability to describe effects of the particle continuum is
discussed. The sensitivity of predicted locations of one- and two-particle drip
lines to details of the macroscopic-microscopic model is analyzed.Comment: 22 REVTeX pages, 13 uuencoded postscript figures available upon
reques
The possible existence of Hs in nature from a geochemical point of view
A hypothesis of the existence of a long-lived isotope 271Hs in natural
molybdenites and osmirides is considered from a geochemical point of view. It
is shown that the presence of Hs in these minerals can be explained only by
making an additional ad hoc assumption on the existence of an isobaric pair of
271Bh-271Hs. This assumption could be tested by mass-spectrometric measurements
of U, Pb, Kr, Xe, and Zr isotopic shifts.Comment: 5 pages, no figures. Physics of Particles and Nuclei Letters, 2006,
Vol. 3, No. 3, pp. 165-168 in pres
Cluster Interpretation of Properties of Alternating Parity Bands in Heavy Nuclei
The properties of the states of the alternating parity bands in actinides,
Ba, Ce and Nd isotopes are analyzed within a cluster model. The model is based
on the assumption that cluster type shapes are produced by the collective
motion of the nuclear system in the mass asymmetry coordinate. The calculated
spin dependences of the parity splitting and of the electric multipole
transition moments are in agreement with the experimental data.Comment: 29 pages, 10 figure
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