S. Yu. Komarov

N and Z dependence of nuclear charge radii

This paper is devoted to the analysis of the general trends in the nucleon number dependence of the experimental root-mean-square (rms) charge radii. It is based on the data obtained by different methods of combined treatment of (i) radii changes determined from optical and—to a lesser extent—Kαx-ray isotope shifts, and (ii) absolute radii measured from muonic and electronic scattering experiments. These methods have recently been developed and now updated including experimental data up to the beginning of 2008. Thus, new sets of rms nuclear radii have been obtained covering 865 isotopes for 76 elements from 1 Ht o96Cm. New information on the isotopic and isotonic behaviour of the nuclear charge radius is obtained with a high accuracy compared to that of the directly measured radii values for the same element. Of special interest is that concerning the light elements and the appearance of non-traditional magic neutron and proton numbers, as N = 6, 14 and Z = 14; the doublemagic properties of 96 Zr are discussed in more detail. A quantitative criterion is introduced, which points to the peculiarities in the radii trend and offers an opportunity to investigate it more closely. The results provide important information which may serve as a guide to incorporate essential new features into the theoretical approaches. (Some figures in this article are in colour only in the electronic version)

Shell structure of even-even nickel isotopes containing twenty to forty neutrons

Shell parameters of even-even nickel isotopes involving twenty to forty neutrons are analyzed, and the results of this analysis are presented. A detailed comparison of the results obtained by calculating, on the basis of the mean-field model with the Koura-Yamada potential and the dispersive optical potential, single-particle energies of proton and neutron subshells with experimental data on the isotopes 56,58,60,62,64,68Ni and with evaluated data on the neutron-deficient isotopes 48,50,52,54Ni is performed.

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.

Parameters of the 64,66,68,70Zn single-particle structure

Populations and energies of neutron subshells in 64, 66, 68, 70Zn and proton subshells in 64, 66, 68Zn are found from the joint evaluation of the data on stripping and pickup reactions and data on spins and parities of nuclear states. The analysis of the thus obtained parameters made it possible to find population features of the nucleon subshells in the nuclei mentioned. A relation between these features and the available data on the first excited 2+ states and deformations in this region of nuclei is shown.

Analysis of the new data on single-particle structure of nuclei from the middle of the 1f–2p shell within the dispersive optical model

On the basis of the most reliable experimental information about the single-particle energies of neutron and proton states in 2048Ca28, 2250Ti28, 2452Cr28, and 2654Fe28 nuclei, single-particle energies in mirror 2848Ni20, 2850Ni22, 2852Ni24 and 2854Ni26 nuclei have been evaluated. The evaluated single-particle energies are compared with the energies calculated within the dispersive optical model. Good agreement between the calculated and experimental single-particle energies is demonstrated.

Neutron shell structure of 58,60,62,64Ni nuclei and its study within a mean-field model with dispersive optical-model potential

Experimental single-particle energies and occupation probabilities for neutron states near the Fermi energy in 58,60,62,64Ni nuclei were obtained from joint evaluation of the data on nucleon stripping and pickup reactions on the same nucleus. Degeneracy of the 2p3/2,1/2 and 1f5/2 subshells was demonstrated. The resulting data were analyzed within a mean-field model with dispersive optical-model potential. Good agreement was obtained between the calculated and experimental single-particle energies of the subshells.

New nuclear charge radii database

Several large relational databases (DBs) containing various atomic nucleus parameters and nuclear reaction features were produced at the Centre for Photonuclear Experiments Data (Centr Dannyh Fotoyadernykh Eksperimentov (CDFE)) of the Skobeltsyn Institute of Nuclear Physics, Moscow State University). The sources are numerical data founds maintained by International Nuclear Data Centers Network of the International Atomic Energy Agency (IAEA) and produced by CDFE. The original CDFE product is the electronic “Chart of Quadrupole Nuclear Deformations” which includes ∼2000 sets of data on nuclei quadrupole moments Q and quadrupole deformation parameters β2 for ∼1500 nuclei. At last time, in the frame of joint research with the Joint Institute for Nuclear Research (JINR) that electronic Chart was supplemented with the data on nuclear mean-root-square (MRS) charge radii (∼900 isotopes of 90 elements (Z = 1–96, N = 0–152)) and therefore transformed into the “Chart of Nucleus Shape and Size Parameters”—complete collection of data under discussion. New Chart allows one to investigate the isotopic and isotonic behavior of nuclei quadrupole moments, parameters of quadrupole deformation and charge radii, and study the R(Z, N) surface structure and R(A) dependence of the fine structure.

A New Database (Digital Chart) of Main GDR Parameters

A new digital chart of the main parameters (energy, amplitude, width, some integrated values) of the giant dipole resonance (GDR) of atomic nuclei is developed. For many nuclei investigated in photonuclear reactions, the data are presented on the corresponding resonances appearing in cross sections of the reactions of main nucleus GDR excitation and decay channels, i.e., the total photoabsorption (γ, abs), reactions with formation of neutron (γ, xn), (γ, n), and (γ, 2n) and proton (γ, p), and others (with the formation of deuterons (γ, d), tritons (γ, t), and α-particles (γ, α)). The chart has a useful and convenient scaling tool: a digital zoom that makes navigation around the chart much easier and convenient. Through the table of search request processing results, the chart is connected with several other databases containing information on reactions in the cross section of which a GDR is observed, the target and final nuclei of these reactions, and a corresponding international bibliography database (DB) data sets.

Shell structure of new magic nuclei: Systematics of features

Investigation of the structure of the upper shells of new magic nuclei revealed an empirical regularity with the following characteristic feature: closed proton and neutron subshells, with identically large total angular momenta (j = j coupling), are located near the Fermi energy and there is a closed subshell with j = 1/2 above one of them. The properties of the nuclei exhibiting this feature of closed upper proton and neutron subshells have been investigated in detail. Quantitative manifestation of the new magicity effects, depending on the occupancy of the corresponding subshells with nucleons, has been analyzed. Several nuclei have been found, which, obviously, also have magic properties, and all classical, new magic, and nonmagic oxygen isotopes 14–48O have been considered from the new point of view.