Fine structure of the pygmy quadrupole resonance in ${}^{112,114}$Sn isotopes

Abstract

The electric quadrupole response in ${}^{112,114}$Sn isotopes is investigated by energy-density functional (EDF) and three-phonon quasiparticle-phonon model (QPM) theory with special emphasis on 2${}^{+}$ excitations located above the first collective quadrupole state and below 5 MeV. Additional quadrupole strength clustering as a sequence of states similar to the recently observed pygmy quadrupole resonance in ${}^{124}$Sn is found. The spectral distributions and transition densities of these 2${}^{+}$ states show special features being compatible with oscillations of a neutron skin against the isospin-symmetric nuclear core. Furthermore, two new ($p$, $p^{\prime }\gamma$) Doppler-shift attenuation (DSA) coincidence experiments were performed at the SONIC@HORUS setup. Quadrupole states with excitation energies up to 4.2 MeV were populated in ${}^{112,114}$Sn. Lifetimes and branching ratios were measured allowing for the determination of the reduced quadrupole transition strengths to the ground state. A stringent comparison of the new data to EDF+QPM theory in ${}^{112}$Sn and ${}^{114}$Sn isotopes hints at the occurrence of a low-energy quadrupole mode of unique character which could be interpreted as pygmy quadrupole resonance.

6 pages, 4 figures, 1 table

References in corpus (13)

• Exotic modes of excitation in atomic nuclei far from stability
• Pygmy dipole resonance as a constraint on the neutron skin of heavy nuclei
• Investigation of Pygmy Dipole Resonances in the Tin Region
• Pygmy Resonances and Neutron Skins
• Pygmy dipole strength in 90Zr
• Low-energy electric dipole response in 120Sn
• Low-energy dipole strength in 112,120Sn
• Pygmy and core polarization dipole modes in ${}^{206}$Pb: connecting nuclear structure to stellar nucleosynthesis
• Shape coexisistence and collective low-spin states in ${}^{112,114}$Sn studied with the $(p,p^{\prime }\gamma )$ DSA coincidence technique
• Nuclear structure and reaction studies at SPIRAL
• Low-energy quadrupole states in neutron-rich tin nuclei
• Combining γ-ray and particle spectroscopy with SONIC@HORUS
• Lifetime measurement of excited low-spin states via the $(p,p^{\prime }\gamma$) reaction

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