E. A. Romanovskii

Calculation of single-particle energies of bound nucleon states in nuclei with 40 ≤ A ≤ 208 using global parameters of dispersive optical model potential

Single-particle energies of bound neutron and proton states in nuclei with mass numbers 40 ≤ A ≤ 208 are calculated within the dispersive optical model with different sets of global parameters. The results of the calculation are compared with the experimental data and the predictions of the relativistic mean-field model.

Calculating neutron single-particle energies for Zr isotopes near N = 50, 70, 82

The neutron single-particle energies for Zr isotopes with neutron number N near 50, 70, and 82 are calculated using a mean field model with spherical dispersive optical potential. The calculated energy values are in good agreement with experimental data and with predictions according to mass formula KTUY05.

Energies of the single-particle proton 1f and 2p states in the 58,60,62,64Ni isotopes

Single-particle energies corresponding to the maximum value of the spectroscopic factor were obtained for the proton states near the Fermi energy in the 58,60,62,64Ni nuclei by the joint evaluation of the data on the stripping and pickup reactions on the same nucleus. These results are compared with the center-of-gravity energies of the single-particle state fragment distributions obtained by the same method and with the single-particle energies calculated with the potential of X. Koura and M. Yamada and with the dispersive optical model potential. The single-particle state fragmentation effect is discussed.

Analysis of single-particle energies of the neutron states in the 64,66,68,70Zn isotopes within a mean field model with dispersive optical potential

The dynamics of the shell parameters of 64, 66, 68, 70Zn nuclei close to the Fermi energy, obtained by the joint evaluation of data from the stripping and pick-up reaction of a nucleon on one and the same nucleus, demonstrates how the difference between the neutron single-particle spectra of the levels of 70Zn and 68Ni nuclei with the number N = 40 arises. The experimental data are analyzed within a mean field model with dispersive optical potential. The calculation results describe very well the dimunution of the energy gap between the 1g9/2 and 2p1/2 levels in Zn isotopes, in comparison with Ni isotopes.

New Magic Nuclei and Conditions of Their Formation

The systematic studies of the arrangement features of single-particle nucleon subshells in even-even 90,92,94,96Zr isotopes and behavior of some known “magicity parameters” in isotopes and isotones neighboring the 96Zr nucleus have led to the interpretation of 96Zr as a new doubly magic nucleus. Analysis of the structure of nucleon shells in the 96Zr nucleus revealed a feature, which consisted in that near the Fermi energy it had filled proton (π1f5/2) and neutron (v2d5/2) subshells with an identical and large total momentum j = 5/2, which was called the j-j coupling. Above the π1f5/2 shell, there is another filled shell (π2p1/2) with two j = 1/2 protons. Applied to other filled shells, this empirical rule allowed revealing several new nontraditional magic nuclei: 96Sr (Z = 38, N = 58), π1f5/2, v2d5/2, and v3s1/2 subshells; 54Ca (Z = 20, N = 34), π2p3/2, v1d3/2, and v2p1/2 subshells; a pair of 30Si (Z = 14, N = 16) and 30S (Z = 16, N = 14) nuclei, π1d5/2, v1d5/2, and (π/v)2s1/2 subshells; and a pair of 14C (Z = 6, N = 8) and 14O (Z = 8, N = 6) nuclei, 1p3/2, v1p3/2, and v2p1/2 subshells. The existence of the magic nuclei 52,54Ca is widely discussed in the literature, the possibility of the existence of the other nuclei found is confirmed by the systematics of the behavior of the “magicity” parameters. The fact that shells with some nucleon numbers different from the classical magic numbers are closed may be due to the manifestation of a new type of interaction between nuclear protons and neutrons occupying certain subshells.

Neutron single-particle structure of 48Ca, 50Ti, 52Cr, 54Fe, and 56Ni nuclei

The change in the neutron single-particle structure of (1f−2p)-shell magic nuclei near the Fermi energy with an increase in the number of protons in the 1f7/2 subshell from 0 for 48Ca to 8 for 56Ni has been investigated. Good agreement of the experimental and estimated values of the single-particle energies Enlj of the bound states of neutrons in these nuclei with the results of calculations within the dispersive optical model is obtained.

Analysis of single-particle energies of doubly magic 100,132Sn nuclei within the dispersive optical model

Extrapolation of the single-particle energies Enlj of the bound states of neutrons and protons in the 112,116,118,120,124Sn isotopes has been performed to estimate the values of Enlj for unstable doubly magic 50100Sn50 and 50132Sn82 nuclei. The estimates obtained are compared with the data derived from the analysis of the decay spectra of neighboring radioactive nuclei and with the results of the calculation within the dispersive optical model.

Calculation of single-particle energies in the 2856Ni28 and 2878Ni50 nuclei within the mean field model with the dispersive optical potential

Parameters of the neutron and proton dispersive optical potentials were determined by the earlier developed method for the unstable double magic nuclei 2856Ni28 and 2878Ni50. They were used to calculate the neutron and proton single-particle energies of these nuclei near the Fermi energy. Good agreement with the experimental data is obtained.

Calculation of single-particle energies in the 3896Sr nucleus within the mean field model with the dispersive optical potential

Evaluated and experimental neutron single-particle energies of the 88, 94, 96Sr and 90, 96, 98Zr nuclei near the Fermi energy are compared. A possibility of formation of a considerable particle-hole gap in the 94, 96Sr typical of traditional magic nuclei is investigated. Agreement is obtained between the single-particle energies calculated within the mean field model with the dispersive optical potential and the evaluated energies for the 94, 96Sr nuclei.

On double magicity of the 28 68 Ni40 nucleus

Single-particle energies Enlj of neutron states in the 2868Ni40 nucleus are estimated on the basis of extrapolation of the experimental values of Enlj in the 58,60,62,64Ni isotopes. The data obtained are compared with the results of calculation within the dispersion optical model.