Low-energy dipole strength in 112,120Sn

Abstract

The 112,120Sn(gamma,gamma') reactions below the neutron separation energies have been studied at the superconducting Darmstadt electron linear accelerator S-DALINAC for different endpoint energies of the incident bremsstrahlung spectrum. Dipole strength distributions are extracted for 112Sn up to 9.5 MeV and for 120Sn up to 9.1 MeV. A concentration of dipole excitations is observed between 5 and 8 MeV in both nuclei. Missing strength due to unobserved decays to excited states is estimated in a statistical model. A fluctuation analysis is applied to the photon scattering spectra to extract the amount of the unresolved strength hidden in background due to fragmentation. The strength distributions are discussed within different model approaches such as the quasiparticle-phonon model and the relativistic time blocking approximation allowing for an inclusion of complex configurations beyond the initial particle-hole states. While a satisfactory description of the fragmentation can be achieved for sufficently large model spaces, the predicted centroids and total electric dipole strengths for stable tin isotopes strongly depend on the assumptions about the underlying mean field.

arXiv comment14 pages, 12 figures, revised version, accepted for publication in Phys. Rev. C

References in corpus (43)

• Constraints on the symmetry energy and neutron skins from experiments and theory
• Exotic modes of excitation in atomic nuclei far from stability
• Complete electric dipole response and the neutron skin in 208Pb
• The information content of a new observable: the case of the nuclear neutron skin
• Nuclear Level Density and the Determination of Thermonuclear Rates for Astrophysics
• Constraints on the symmetry energy and on neutron skins from the pygmy resonances in 68Ni and 132Sn
• Magnetic dipole excitations in nuclei: elementary modes of nucleonic motion
• Microscopic HFB+QRPA predictions of dipole strength for astrophysics applications
• Pygmy dipole resonance as a constraint on the neutron skin of heavy nuclei
• Isospin Character of the Pygmy Dipole Resonance in 124Sn
• Investigation of Pygmy Dipole Resonances in the Tin Region
• Pygmy Resonances and Neutron Skins
• Relativistic quasiparticle time blocking approximation. Dipole response of open-shell nuclei
• Concentration of electric dipole strength below the neutron separation energy in N = 82 nuclei
• Dipole states in stable and unstable nuclei
• Probing the Nuclear Neutron Skin by Low-Energy Dipole Modes
• Pygmy dipole strength in 90Zr
• Large-scale Continuum Random Phase Approximation predictions of dipole strength for astrophysical applications
• Particle-vibration coupling within covariant density functional theory
• Self-consistent description of multipole strength: systematic calculations
• Pygmy dipole resonance in 208Pb
• Emergence of pygmy dipole resonances: Magic numbers and neutron skins
• Mode-coupling and the pygmy dipole resonance in a relativistic two-phonon model
• Low-lying dipole response in the Relativistic Quasiparticle Time Blocking Approximation and its influence on neutron capture cross sections
• Low-lying dipole response: isospin character and collectivity in ${}^{68}$Ni, ${}^{132}$Sn and ${}^{208}$Pb
• Information content of the low-energy electric dipole strength: correlation analysis
• Low-energy isovector and isoscalar dipole response in neutron-rich nuclei
• Isotopic dependence of the pygmy dipole resonance
• Neutron skins and neutron stars
• Fragmentation and systematics of the Pygmy Dipole Resonance in the stable N=82 isotones
• Population of dipole states via isoscalar probes: the splitting of pygmy dipole resonance in ${}^{124}$Sn}
• The high-efficiency γ-ray spectroscopy setup γ3 at HIγS
• Direct determination of photodisintegration cross sections and the p-process
• Self-consistent calculations of the strength function and radiative neutron capture cross section for stable and unstable tin isotopes
• Fine structure of the isovector giant dipole resonance in 208Pb: Characteristic scales and level densities
• Relativistic two-phonon model for low-energy nuclear response
• Relativistic Continuum Quasiparticle Random Phase Approximation in Spherical Nuclei
• Low-energy electric dipole response of Sn isotopes
• Evolution of the pygmy dipole resonance in nuclei with neutron excess
• Pygmy Dipol Resonances as a Manifestation of the Structure of the Neutron-Rich Nuclei
• Two-phonon 1- state in 112Sn observed in resonant photon scattering
• Pygmy and giant electric dipole responses of medium-heavy nuclei in a self-consistent Random Phase Approximation approach with finite-range interaction
• Level density of 2+ states in 40Ca from high energy-resolution (p,p') experiments

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• Soft breathing modes in neutron--rich nuclei with the subtracted second random--phase approximation
• Pygmy resonances: what's in a name?
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