Medium-heavy Spherical Nuclei Research Articles

Semimicroscopic Description of High-Energy Charge-Exchange Spin-Monopole Excitations in Medium-Heavy Spherical Nuclei

The semimicroscopic particle–hole dispersive optical model developed recently is applied to describing main properties of the Gamow–Teller and charge-exchange giant spin-monopole resonances in medium-heavy closed-shell nuclei. The description in question includes energy-averaged strength functions, projected transition densities, and partial branching ratios for direct single-nucleon decay. By way of example, this approach is implemented for the $${}^{208}$$ Pb parent nucleus. The results of respective calculations are compared with available experimental data.

Coulomb Description of High-Energy Charge-Exchange Monopole Excitations in Medium-Heavy Spherical Nuclei

The recently proposed approach to the description of high-energy charge-exchange monopole excitations in medium-heavy spherical nuclei is implemented to quantitatively estimate the main damping parameters of the related giant resonances including the isobaric analog resonance. The approach consists in incorporating the “Coulomb description” of isospin-forbidden processes into the particle-hole dispersive optical model. The results obtained for a few parent nuclei with $$Z = 50$$ and $$Z = 82$$ are compared with the respective experimental data.

Damping parameters of charge-exchange giant monopole resonances within a semi-microscopic approach

The recently proposed semi-microscopic approach, which consists in incorporating the “Coulomb description” of isospin-forbidden processes into the particle-hole dispersive optical model, is implemented to evaluate the main damping parameters of charge-exchange giant monopole resonances (including isobaric analog resonances) in medium-heavy spherical nuclei. The calculation results obtained for the 208Pb and 209Pb parent nuclei are compared with available experimental data.

Unitary version of the single-particle dispersive optical model and single-hole excitations in medium-heavy spherical nuclei

A unitary version of the single-particle dispersive optical model was proposed with the aim of applying it to describing high-energy single-hole excitations in medium-heavy mass nuclei. By considering the example of experimentally studied single-hole excitations in the 90Zr and 208Pb parent nuclei, the contribution of the fragmentation effect to the real part of the optical-model potential was estimated quantitatively in the framework of this version. The results obtained in this way were used to predict the properties of such excitations in the 132Sn parent nucleus.

One-quasiparticle strength functions in medium-heavy spherical nuclei

A method to describe quantitatively the one-quasiparticle strength functions is proposed which takes approximately into account the coupling of one-quasiparticle states to many-phonon configurations. The method is used to interpret the appropriate experimental data for medium-heavy spherical nuclei. The results are compared with the calculations made in different theoretical approaches.

Derivation of a proximity interaction between nuclei from the Hartree-Fock functional with Skyrme interactions

The potential between heavy or medium heavy spherical nuclei is derived on the basis of the proximity approximation and the assumption of undisturbed spherical density distributions. The HF-theory with Skyrme forces is used to write the energy as a functional of the density. The resulting potential consists of an isoscalar and a (much smaller) isospin-dependent part. Depending on the choice of the Skyrme parameters calculated interaction between heavy ions are close to the double folding potential or to the proximity potential. Our interaction can be factorized with a very good approximation into scaling factors and universal functions of the proximity distance in units of the surface thickness.

Electromagnetic properties of the11/2−states inSn111andSn113

In order to study the core polarization effects in medium heavy spherical nuclei the mean lives and $g$ factors of the ${11/2}^{\ensuremath{-}}$ states in $^{111}\mathrm{Sn}$ and $^{113}\mathrm{Sn}$ have been measured. The isomeric states were populated by the $^{111}\mathrm{Cd}(\ensuremath{\alpha},2n)^{113}\mathrm{Sn}$ and $^{107,109}\mathrm{Ag}(^{7}\mathrm{Li},3n)^{111,113}\mathrm{Sn}$ reactions with pulsed $\ensuremath{\alpha}$ and $^{7}\mathrm{Li}$ beams. The nuclear spin precession in the 60 kG field of an on-line superconducting magnet was observed time differentially. The following values were obtained: $^{111}\mathrm{Sn}$ ${(11/2}^{\ensuremath{-}}$, 979.6 keV): $\ensuremath{\tau}=13.3(15)$ ns, $g=\ensuremath{-}0.23(2)$; $^{113}\mathrm{Sn}$ ${(11/2}^{\ensuremath{-}}$, 740 keV): $\ensuremath{\tau}=118.5(25)$ ns, $g=\ensuremath{-}0.235(4)$. The magnetic moments of the ${11/2}^{\ensuremath{-}}$ states in $^{111,113,115,119}\mathrm{Sn}$ and their near constancy as a function of mass number are reproduced by a first order $M1$ core polarization calculation using pairing model wave functions, experimentally determined energy denominators, and occupancy parameters. The strong reduction of the $M2$ rates for the ${h}_{\frac{11}{2}}\ensuremath{\rightarrow}{g}_{\frac{7}{2}}$ transition as compared to the single particle estimate shows the destructive effect of the spin-isospin $M2$ core polarization.NUCLEAR REACTIONS $^{111}\mathrm{Cd}(\ensuremath{\alpha},2n)$, $^{107,109}\mathrm{Ag}(^{7}\mathrm{Li},3n)$, ${E}_{\ensuremath{\alpha}}=21$ MeV, ${E}_{\mathrm{Li}}=30$ MeV; measured $\ensuremath{\tau}$ and $\ensuremath{\mu}$ (${\frac{11}{2}}^{\ensuremath{-}}$ states in $^{111,113}\mathrm{Sn}$). Isotopic and natural metal targets.