Self-consistent Theory Of Finite Fermi Systems Research Articles

Spectroscopic factors of magic and semimagic nuclei within the self-consistent theory of finite Fermi systems

A scheme is presented to find single-particle spectroscopic factors (SF) of magic and semimagic nuclei within the self-consistent theory of finite Fermi systems (TFFS). In addition to the energy dependence of the mass operator Σ induced by the surface-phonon coupling effects which are commonly considered in this problem, the in-volume energy dependence of the operator Σ inherent in the self-consistent TFFS is also taken into account. This dependence arises due to the effect of high-lying particle-hole excitations and persists in nuclear matter. The self-consistent basis of the energy density functional method by Fayans et al. is used. Both the surface and in-volume contributions to the SFs turned out to be of comparable magnitude. The results for magic 40,48Ca and 208Pb nuclei and semimagic lead isotopes are presented.

Description of magnetic moments of long isotopic chains within the FFS theory

Dipole magnetic moments of several long isotopic chains are analyzed within the self-consistent finite Fermi system theory with exact account for the pairing and quasiparticle continuum. The momentum dependence of the spin-isospin Landau-Migdal amplitude g′ is taken into account. This dependence was introduced previously to describe high-energy electron magnetic scattering. New moment data for nuclei far from the \( \beta\) -stability valley are included in the analysis. For a number of semi-magic isotopes of the tin and lead chains a good description of the data is obtained, with an accuracy of 0.1- 0.2\( \mu_{{N}}^{}\) . A chain of non-magic isotopes of copper is also analyzed in detail.

Properties of nuclei near the neutron-drip line in O – Si region

The analysis of stability and properties of the neutron drip-line isotopes in O – Si region is performed using self-consistent theory of finite Fermi systems (STFFS). The T 1 2 values for new discovered Ne and Na isotopes are calculated. Two-neutron instability of nuclei for extra drip-line nuclei like 26O is discussed. Conclusions about vanishing of N=20 and N=28 as nuclear “magic” numbers and appearance of new drip line numbers N=16 and N=26 are given.

Ground state properties and β-decay half-lives near 132Sn in a self-consistent theory

The self-consistent finite Fermi-system theory with three different parameter sets is used to calculate decay energies and Gamow-Teller strength distributions of neutron-rich short-lived nuclides near shell closures Z=50, N=82. Among the parameters, the role of a strong surface neutronproton attraction and an isovector spin-orbit force is discussed. The obtained β-decay half-lives are compared with large-scale calculation results and with available experimental data. Some predictions for the ground state properties of other unstable closed-shell nuclei are presented.

Gamow-Teller strength functions of superfluid odd- A nuclei and neutrino capture reactions

The charge-exchange excitations of superfluid odd- A nuclei are studied within the framework of the self-consistent finite Fermi-system theory. The pairing blocking effects due to the odd quasiparticle, the effective NN-interactions both in the particle-hole (ph) and particle-particle (pp) channel, and also the ph-continuum are taken into account. Gamow-Teller strength functions of 71Ga, 115In and 19F nuclei are calculated and compared with those extracted from experimental spectra of (p,n) reactions. The total capture cross sections of the reactor electron antineutrinos are calculated (assuming complete ν e → ν e conversion), as well as the solar-neutrino capture rates for the 71Ga and 115In+ 19F detectors. Uncertainties regarding nuclear-structure information involved in these calculations are discussed.

Ground-state charge distribution and transition charge densities of the low-lying states in 86Sr.

Differential cross sections for electron scattering from $^{86}\mathrm{Sr}$ have been measured for excited states below 3.5 MeV over a range of effective momentum transfer of 0.4 to 2.8 ${\mathrm{fm}}^{\mathrm{\ensuremath{-}}1}$. The elastic scattering data have been analyzed to reconstruct the ground-state charge distribution. The inelastic scattering data have been analyzed to extract transition charge densities. Interpretation of the underlying nuclear structure is given in the framework of a self-consistent finite Fermi system theory.

Transition densities of collective excitations in 118Sn.

Electron scattering cross sections have been measured for the elastic and the first ${2}^{+}$,${3}^{\mathrm{\ensuremath{-}}}$ and low-lying ${4}^{+}$ excitations in $^{118}\mathrm{Sn}$. Forward angle data were taken for momentum transfers in the range 1.24q2.74 ${\mathrm{fm}}^{\mathrm{\ensuremath{-}}1}$ allowing the extraction of transition charge densities in a Fourier-Bessel analysis. Comparisons are made with microscopic calculations performed in the framework of the self-consistent finite Fermi system theory and quasiparticle phonon approach.

Interplay between single-particle and collective degrees of freedom in the excitation of the low-lying states in 140Ce.

Differential cross sections for electron scattering from $^{140}\mathrm{Ce}$ have been measured for excitation energies less than 3.3 MeV over a range of effective momentum transfer of 0.4 to 3.1 ${\mathrm{fm}}^{\mathrm{\ensuremath{-}}1}$. The data have been analyzed to extract transition charge densities. These densities are interpreted in terms of a quasiparticle-phonon model and self-consistent finite Fermi system theory to disentangle the collective and noncollective modes of excitation.