arXiv subjects

Z. Lojewski

Publications and source records attributed to Z. Lojewski.

7 recordsLinked to original sources

arXiv2006

Pairing and alpha-decay

Nuclear pairing interaction plays a crucial role in both macroscopic-microscopic and fully macroscopic descriptions of nuclei. In the present study we discuss different pairing interactions (monopole and delta pairing forces) and the methods allowing for the particle number symmetry restoration in addition to the customary BCS treatment of pairing correlations in the context of $α$-decay half-lives for superheavy nuclei. The calculations are done in the macroscopic-microscopic framework for even-even nuclei with Z > 110.

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arXiv2003

State dependent $δ$-pairing and spontaneous fission

We examine the fission barriers, mass parameters and spontaneous fission half lives of fermium isotopes within the framework of macroscopic-microscopic model with a $δ$-pairing interaction. Four different macroscopic models are applied and studied. The results are compared to experimental data and to the corresponding monopole pairing ones. The half lives obtained in the $δ$-pairing model are comparable with experimental data. The state-dependence of pairing has an important effect on the calculated fission half-lives.

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arXiv2003

The alpha decay of deformed superheavy elements

The interaction potential between the alpha particle and the deformed parent nucleus was used for description of the decay of superheavy nuclei. It consists of centrifugal, nuclear and Coulomb parts suitably modified for deformed nuclei. The significant effect of various shapes of barriers obtained for deformed parent nuclei on calculated alpha half-life times were shown. The finally calculated half-life times due to the spontaneous alpha decay for superheavy elements were compared with the results obtained from other models and the experimental data.

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arXiv1997

Ground state properties of the $β$ 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 $β$ stable even-even nuclei with $16 \leq A \leq 256$. 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.

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arXiv1996

Stability of the Heaviest Nuclei on Spontaneous-Fission and Alpha-Decay

Spontaneous-fission half-lives of the heaviest even-even nuclei are evaluated and compared with their alpha-decay mode. Calculations of spontaneous-fission half-lives are performed in the dynamical way with potential energy obtained by the macroscopic-microscopic method and the inertia tensor obtained by the cranking approximation. The alpha-decay half-lives are calculated for the same region of nuclei by use of the Viola and Seaborg formula. The ground-state properties such as mean square radii and electric quadrupole moments are also studied. From the analysis of spontaneous-fission half-life values it is found that a peninsula of deformed metastable superheavy nuclei near Z=106 and N=162 is separated from an island of the spherical superheavy, around the doubly magic nucleus with Z=114 and N=184, by a trench in the vicinity of neutron number N=170.

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arXiv1996

Influence of Different Collective Coordinates on Spontaneous Fission Process in Fm Isotopes

We study the role of different collective degrees of freedom in spontaneous fission process of even--even Fm isotopes. To find a proper collective space we examine a reach collection of nuclear shape parameters $\{β_λ\}$, with $λ$=2,3,4,5,6 and 8; as well as the paring degrees of freedom i.e. proton $Δ_{p}$ and neutron $Δ_{n}$ pairing gaps. On the basis of the multidimensional dynamic--programming method (MDPM) the optimal collective space $\{β_{2}, β_{4}, β_{6}, Δ_{p}, Δ_{n}\}$ for Fm isotopes was found.

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arXiv1996

Some New Aspects of Bimodal Fission in 258Fm Isotope

Using the multidimensional dynamic--programming method (MDPM) in the four--dimensional deformation space $\{β_λ\}$ with $λ$=2, 4, 35 and 6 we were able to study evolution of the action integral for the fissioning nucleus $^{258}$Fm. We found the second minimum on the cross--section of the action integral for $β_2 \approx 1$ , what we interpret as the dynamical evidence of the bimodal fission in this heavy Fm isotope.

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