Self-consistent calculations of the strength function and radiative neutron capture cross section for stable and unstable tin isotopes

Abstract

The E1 strength function for 15 stable and unstable Sn even-even isotopes from A=100 till A=176 are calculated using the self-consistent microscopic theory which, in addition to the standard (Q)RPA approach, takes into account the single-particle continuum and the phonon coupling. Our analysis shows two distinct regions for which the integral characteristics of both the giant and pygmy resonances behave rather differently. For neutron-rich nuclei, starting from ${}^{132}$Sn, we obtain a giant E1 resonance which significantly deviates from the widely-used systematics extrapolated from experimental data in the $\beta$-stability valley. We show that the inclusion of the phonon coupling is necessary for a proper description of the low-energy pygmy resonances and the corresponding transition densities for $A<$132 nuclei, while in the $A>132$ region the influence of phonon coupling is significantly smaller. The radiative neutron capture cross sections leading to the stable ${}^{124}$Sn and unstable ${}^{132}$Sn and ${}^{150}$Sn nuclei are calculated with both the (Q)RPA and the beyond-(Q)RPA strength functions and shown to be sensitive to both the predicted low-lying strength and the phonon coupling contribution. The comparison with the widely-used phenomenological Generalized Lorentzian approach shows considerable differences both for the strength function and the radiative neutron capture cross section. In particular, for the neutron-rich ${}^{150}$Sn, the reaction cross section is found to be increased by a factor greater than 20. We conclude that the present approach may provide a complete and coherent description of the $\gamma$-ray strength function for astrophysics applications. In particular, such calculations are highly recommended for a reliable estimate of the electromagnetic properties of exotic nuclei.

References in corpus (12)

• The r-process of stellar nucleosynthesis: Astrophysics and nuclear physics achievements and mysteries
• Exotic modes of excitation in atomic nuclei far from stability
• Investigation of Pygmy Dipole Resonances in the Tin Region
• Relativistic quasiparticle time blocking approximation. Dipole response of open-shell nuclei
• Self-consistent description of multipole strength: systematic calculations
• Low-lying dipole response in the Relativistic Quasiparticle Time Blocking Approximation and its influence on neutron capture cross sections
• Relativistic quasiparticle time blocking approximation. II. Pygmy dipole resonance in neutron-rich nuclei
• Dependence of single-particle energies on coupling constants of the nuclear energy density functional
• Astrophysical relevance of $\gamma$ transition energies
• Microscopic description of the pygmy and giant electric dipole resonances in stable Ca isotopes
• Extended Theory of Finite Fermi Systems: Application to the collective and non-collective E1 strength in ${}^{208}$Pb
• Self-consistent calculations within the Green's function method including particle-phonon coupling and the single-particle continuum

Cited by in corpus (11)

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• A self-consistent study of multipole response in neutron-rich nuclei using a modified realistic potential
• Evolution of the dipole polarizability in the stable tin isotope chain
• Impact of the phonon coupling on the photon strength function
• Continuum quasiparticle random phase approximation for astrophysical direct neutron capture reaction of neutron-rich nuclei
• Effects of phonon-phonon coupling on properties of pygmy resonance in ${}^{124-132}$Sn
• QRPA calculations for M1 transitions with the noniterative finite amplitude method and the application to neutron radiative capture cross sections
• Continuum random-phase approximation for (n,γ) reactions on neutron-rich nuclei: collective effects and resonances