A. Staszczak

Fission barriers and probabilities of spontaneous fission for elements with Z ≥ 100

Abstract This paper briefly reviews recent progress in theoretical studies on fission barriers and fission half-lives of even–even superheavy nuclei. We compare and discuss results obtained in the semi-classical macroscopic–microscopic approach, the self-consistent mean-field models with the Skyrme and Gogny energy density functionals and in the relativistic mean-field theory. A short part of the paper is devoted to the calculation of the mass parameters and nuclear fission dynamics. We also discuss the predictive power of Skyrme energy density functionals applied to key properties of the fission path of 266Hs. Standard techniques of error estimates in the framework of a χ 2 analysis are applied.

Influence of the pairing vibrations on spontaneous fission probability

Abstract The potential-energy surface and the mass parameters of the even-even transplutonium elements are evaluated. Our microscopic hamiltonian consists of the Nilsson potential, the two-body residual interaction in the local approximation and the pairing forces. The calculations are performed in the generator coordinate method with the extended gaussian-overlap approximation. The coupling of the pairing vibrations with the fission mode (elongation and neck) reduces the WKB estimates of the fission lifetimes by a few orders of magnitude.

Coupling of the pairing vibrations with the fission mode

Abstract The influence of collective pairing vibrations on the spontaneous fission lifetimes are studied. The Nilsson single-particle potential plus the monopole pairing residual interaction are used. The collective hamiltonian is obtained within the cranking model. The fission lifetimes are evaluated in the WKB approximation along the least-action trajectory in the three-dimensional space (e 24 , Δ p , Δ n ) . When taking into account the mean paring-field parameters (Δ p , Δ n ) as dynamical variables, the theoretical fission lifetimes decrease by a few orders of magnitude.

Toroidal high-spin isomers in light nuclei with N ≠ Z

The combined considerations of both the bulk liquid-drop-type behavior and the quantized aligned rotation with cranked Skyrme–Hartree–Fock approach revealed previously (Staszczak and Wong 2014 Phys. Lett. B 738 401) that even–even, N = Z, toroidal high-spin isomeric states have general occurrences for light nuclei with . We find that in this mass region there are in addition toroidal high-spin isomers when the single-particle shells for neutrons and protons occur at the same cranked frequency Examples of toroidal high-spin isomers, S20(I = 74) and Ar22(I = 80,102), are located and examined. The systematic properties of these toroidal high-spin isomers fall into the same regular (multi-particle)-(multi-hole) patterns as other N = Z toroidal high-spin isomers.

PARTICLE-HOLE NATURE OF THE LIGHT HIGH-SPIN TOROIDAL ISOMERS

Nuclei under non-collective rotation with a large angular momentum above some threshold can assume a toroidal shape. In our previous work, we showed by using cranked Skyrme Hartree Fock approach that even even, N = Z, high-K, toroidal isomeric states may have general occurrences for light nuclei with 28 < A < 52. We present here some additional results and systematics on the particle-hole nature of these high-spin toroidal isomers.

A region of high-spin toroidal isomers

Abstract The combined considerations of both the bulk liquid-drop-type behavior and the quantized angular momentum reveal that high-spin toroidal isomeric states may have general occurrences for light nuclei with 28 ⩽ A ⩽ 52 . High-spin N = Z toroidal isomers in this mass region have been located theoretically using cranked self-consistent constraint Skyrme–Hartree–Fock model calculations.

COMPARISON OF SELF-CONSISTENT SKYRME AND GOGNY CALCULATIONS FOR LIGHT Hg ISOTOPES

The ground-state properties of neutron-deficient Hg isotopes have been investigated by the constrained self-consistent Hartree-Fock-Bogoliubov approach with the Skyrme and Gogny effective forces. In the case of the Skyrme interaction we have also applied the Hartree-Fock+BCS model with the state-dependent δ-pairing interaction. Potential energy surfaces and pairing properties have been compared for the both types of forces.

Theoretical studies of possible toroidal high-spin isomers in the light-mass region

We review our theoretical knowledge of possible toroidal high-spin isomers in the light mass region in 28≤A≤52 obtained previously in cranked Skyrme-Hartree-Fock calculations. We report additional toroidal high-spin isomers in 56Ni with I=114ℏ and 140ℏ, which follow the same (multi-particle) (multi-hole) systematics as other toroidal high-spin isomers. We examine the production of these exotic nuclei by fusion of various projectiles on 20Ne or 28Si as an active target in time-projection-chamber (TPC) experiments.

FISSION QUADRUPOLE MASS PARAMETERS IN HF+BCS AND HFB METHODS

The self-consistent Hartree-Fock+BCS and Hartree-Fock-Bogoliubov methods are compared at large nuclear deformations. The calculations are carried out for the fission pathway and quadrupole mass parameter of 252Fm.

Toroidal high-spin isomers in the nucleus 120304

Strongly deformed oblate superheavy nuclei form an intriguing region where the toroidal nuclear structures may bifurcate from the oblate spheroidal shape. The bifurcation may be facilitated when the nucleus is endowed with a large angular moment about the symmetry axis with