Possible existence of pygmy dipole resonance built on excited states in a neutron-rich ${}^{80}$Ge nucleus

Abstract

The pygmy dipole resonance (PDR) at the low-lying tail of the giant dipole resonance (GDR) is an interesting research subject as it carries important information about the nuclear surface with mixed isoscalar and isovector vibrations in $N>Z$ systems. The present paper investigates the possible existence of the PDR built on excited states in a neutron-rich ${}^{80}$Ge nucleus using the phonon damping model (PDM) with and without pairing correlation at zero and finite temperatures. The results obtained within the PDM with exact pairing (EP+PDM) reveal the appearance of two enhanced $\gamma$-transitions $E_{\gamma }=7.25$ and 7.35 MeV at $T=0.6$ MeV, which carry the PDR nature and hence implying the possible existence of PDR built on excited states in this nucleus. These two $\gamma$-energies nicely match with a recent experimental observation, thus indicating the crucial role of the inclusion of exact pairing solution in the precise description of low-lying $\gamma$-transitions. The partition function-based analysis shows that this predicted PDR at $T=$ 0.6MeV is mainly contributed by the first $2^{+}$ excited state of the ${}^{80}$Ge nucleus. The isospin mixing at the nuclear surface is also observed in the investigated PDR at $T=0.6-0.7$ MeV. The primary mechanism underlying the emergence of the hot PDR is found due to the coupling of GDR phonon to non-collective particle-particle and hole-hole configurations at finite temperatures within the PDM framework, along with the shift in particle-hole excitation energies due to thermal pairing correlations

References in corpus (32)

• Exotic modes of excitation in atomic nuclei far from stability
• The information content of a new observable: the case of the nuclear neutron skin
• Constraints on the symmetry energy and on neutron skins from the pygmy resonances in 68Ni and 132Sn
• Where, oh where has the r-process gone?
• Microscopic HFB+QRPA predictions of dipole strength for astrophysics applications
• Quasiparticle random phase approximation based on the relativistic Hartree-Bogoliubov model
• Pygmy dipole resonance as a constraint on the neutron skin of heavy nuclei
• Reference Database for Photon Strength Functions
• Pygmy Resonances and Neutron Skins
• Relativistic quasiparticle time blocking approximation. Dipole response of open-shell nuclei
• Quasiparticle time blocking approximation within the framework of generalized Green function formalism
• Particle-vibration coupling within covariant density functional theory
• Mode-coupling and the pygmy dipole resonance in a relativistic two-phonon model
• Gamma-ray strength function and pygmy resonance in rare earth nuclei
• Microscopic Studies on Two-Phonon Giant Resonances
• Relativistic Random-Phase Approximation with density-dependent meson-nucleon couplings
• Low-lying dipole response: isospin character and collectivity in ${}^{68}$Ni, ${}^{132}$Sn and ${}^{208}$Pb
• Subtraction method and stability condition in the extended RPA theories
• Nuclear level statistics: extending the shell model theory to higher temperatures
• Thermal properties and radiative strengths in 160,161,162Dy
• Evolution of the pygmy dipole resonance in Sn isotopes
• Pygmy and core polarization dipole modes in ${}^{206}$Pb: connecting nuclear structure to stellar nucleosynthesis
• Systematics of strength function sum rules
• Finite-temperature relativistic nuclear field theory: an application to the dipole response
• Exact and approximate ensemble treatments of thermal pairing in a multilevel model
• Nuclear Dipole Response in the Finite-Temperature Relativistic Time Blocking Approximation
• Isoscalar and neutron modes in the E1 spectra of Ni isotopes and the relevance of shell effects and the continuum
• Elasticity of nuclear medium as a principal macrodynamical promoter of electric dipole pygmy resonance
• Giant dipole resonance in ${}^{201}$Tl at low temperature
• Beyond-mean-field effects on the symmetry energy and its slope from the low-lying dipole response of ${}^{68}$Ni
• Experimentally constrained ${}^{165,166}\text{Ho}(n,\gamma )$ rates and implications for the $s$ process
• On the importance of using exact pairing in the study of pygmy dipole resonance

Cited by in corpus (1)

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