B. Nerlo-Pomorska

Nuclear shell structure at very high angular momentum

Abstract A cranked modified-oscillator model (with triaxial shape coordinates ϵ and γ) is used to study the nuclear potential-energy surface (based on a Strutinsky type of shell correction method) for very high angular momenta (30 ≦ I ≦ 100). For this region of spin, pair correlation is assumed to have collapsed. The influence of rapid rotation on the shell structure has been studied in the light and heavy rare-earth region as well as the Te-Ba region. Preliminary studies have also been made in the regions of superheavy and light nuclei. The possible occurrence of yrast traps is discussed.

Microscopic dynamic calculations of collective states in xenon and barium isotopes

Abstract Dynamic calculations of collective states for neutron-deficient doubly even Xe and Ba isotopes are performed. The collective Hamiltonian is constructed in terms of the cranking inertial functions and the macroscopic-microscopic potential, both generated by the single-particle motion in the modified harmonic oscillator potential. The pairing correlations are included. Reduction of the standard pairing interaction strengths leads to results compatible with experiment. The deformation dependence of the inertial functions is found to play an important role.

On the stable octupole deformation of nuclei

Abstract The potential energy of nuclei in the Ra region is studied by a modified macroscopic-microscopic method which accounts for the consistency condition between the macroscopic and microscopic parts of the energy. A stable octupole deformation is obtained for a number of nuclei. The lowest Kπ=0− states are interpreted as being associated with this deformation.

Simple formula for nuclear charge radius

A new formula for the nuclear charge radius is proposed, dependent on the mass numberA and neutron excessN-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.

Ground state properties of the β stable nuclei in various mean field theories

Abstract 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 β stable even-even nuclei with 16 ⩽ A ⩽ 256. 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.

A quantum parity-conserving study on octupole deformation in the light-actinide region☆

Abstract Based on a constrained Hartree-Fock plus BCS calculation with Gogny forces, we construct the collective hamiltonian (GCM+mean field and ATDHF+cranking approach) with the quadrupole and octupole deformations as coordinates. We calculate the 0+, 1− splitting as well as the E1 and E3 transition probabilities for 222Ra. The agreement with experimental results is very good.

The neutron halo in heavy nuclei calculated with the Gogny force

The proton and neutron density distributions, one- and two-neutron separation energies and radii of nuclei for which neutron halos are experimentally observed, are calculated using the self-consistent Hartree-Fock-Bogoliubov method with the effective interaction of Gogny. Halo factors are evaluated assuming hydrogen-like antiproton wave functions. The factors agree well with experimental data. They are close to those obtained with Skyrme forces and with the relativistic mean-field approach.

Equilibrium properties of fast-rotating headed nuclei

Abstract We report on calculations of the equilibrium deformation in excited heated rotating nuclei. At A ∼ 150–200 and temperature t > t c ≈ 1.2 MeV the shell effects turn out to be small to compete with the variations of the liquid drop component of the energy. The transition from the shape of a “cool” nucleus to that of a “hot” nucleus takes place at t c and in deformed nuclei resembles a phase transition. The stiffness parameter with respect to shape variations at t c is anomalously low.

ISOSPIN DEPENDENCE OF PROTON AND NEUTRON RADII WITHIN RELATIVISTIC MEAN FIELD THEORY

Abstract The proton and neutron radii of even-even β-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 evaluated within the relativistic mean field theory is studied. A simple, phenomenological formula for neutron radii is proposed.

Equilibrium deformations for the Ra-Th region of nuclei

Abstract New parameters of the single-particle Nilsson potential for the Ra-Th region have been found. They are: κ p = 0.0561, μ p = 0.702, κ n = 0.0588, μ n = 0.442. The fit is made to the experimental single-particle energy levels in the new quadrupole and hexadecapole equilibrium deformation points, obtained by the shell-correction method with a simple consistency condition. The equilibrium deformations calculated by this method are in good agreement with the experimental data. Experimental values of the quadrupole moments of 222 Rn, 222 Ra and 224 Ra are reproduced for the first time within the Nilsson-plus-Strutinsky method.