Analysis of the neutron and proton contributions to the pygmy dipole mode in doubly magic nuclei

Yüksel, Esra; Khan, E.; Bozkurt, Kutsal

doi:10.1016/j.nuclphysa.2012.01.006

Cited by 31 publications

(22 citation statements)

References 53 publications

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“…In addition, the pygmy dipole strength is found around E ≈ 10 MeV and exhausts 1.2% of the EWSR with the present interaction. Our results are in good agreement with recent experimental results [51] and theoretical works [3,4,49,50]. The IVGDR strength and energy slightly change with increasing temperature.…”

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confidence: 92%

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Multipole excitations in hot nuclei within the finite temperature quasiparticle random phase approximation framework

et al. 2017

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The effect of temperature on the evolution of the isovector dipole and isoscalar quadrupole excitations in 68 Ni and 120 Sn nuclei is studied within the fully self-consistent finite temperature quasiparticle random phase approximation framework, based on the Skyrme-type SLy5 energy density functional. The new low-energy excitations emerge due to the transitions from thermally occupied states to the discretized continuum at finite temperatures, whereas the isovector giant dipole resonance is not strongly impacted by the increase of temperature. The radiative dipole strength at low energies is also investigated for the 122 Sn nucleus, becoming compatible with the available experimental data when the temperature is included. In addition, both the isoscalar giant quadrupole resonance and low-energy quadrupole states are sensitive to the temperature effect: while the centroid energies decrease in the case of the isoscalar giant quadrupole resonance, the collectivity of the first 2 + state is quenched and the opening of new excitation channels fragments the low-energy strength at finite temperatures.

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confidence: 92%

“…In the neutron-rich 68 Ni nucleus, the formation of the pygmy dipole resonance has been predicted within different theoretical models [3,6,49,50]. Recently, the pygmy dipole resonance was also obtained at around 11 MeV using γ decay, following Coulomb excitation of the nucleus on a gold target [7].…”

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confidence: 99%

Multipole excitations in hot nuclei within the finite temperature quasiparticle random phase approximation framework

et al. 2017

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“…In the models the properties of the PDR are very sensitive to the mean-field description and predicted strength might thus be partially shifted to higher excitation energies. One should rather analyze the theoretical transition densities [20,39] to select those with a dominant PDR character.…”

Section: Excitation Ofmentioning

confidence: 99%

Pygmy dipole resonance in208Pb

et al. 2012

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Scattering of protons of several hundred MeV is a promising new spectroscopic tool for the study of electric dipole strength in nuclei. A case study of 208 Pb shows that at very forward angles J π = 1 − states are strongly populated via Coulomb excitation. A separation from nuclear excitation of other modes is achieved by a multipole decomposition analysis of the experimental cross sections based on theoretical angular distributions calculated within the quasiparticle-phonon model. The B(E1) transition strength distribution is extracted for excitation energies up to 9 MeV, i.e., in the region of the so-called pygmy dipole resonance (PDR). The Coulomb-nuclear interference shows sensitivity to the underlying structure of the E1 transitions, which allows for the first time an experimental extraction of the electromagnetic transition strength and the energy centroid of the PDR.

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“…Most often the LES is interpreted as a "pygmy dipole resonance" (PDR) modeled as the oscillation of the neutron excess against the nuclear core [1, [3][4][5]. There are, however, serious objections against such a simplistic collective picture [6,7]. In fact, the landscape of LES may be much richer.…”

Section: Introductionmentioning

confidence: 99%

Toroidal nature of the low-energyE1mode

et al. 2013

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The nature of E1 low-energy strength (LES), often denoted as a "pygmy dipole resonance", is analyzed within the random-phase approximation (RPA) in 208 Pb using Skyrme forces in a fully self-consistent manner. A first overview is given by the strength functions for the dipole, compressional, and toroidal operators. More detailed insight is gained by averaged transition densities and currents where the latter provide a very illustrative flow pattern. The analysis reveals clear isoscalar toroidal flow in the low-energy bin 6.0-8.8 MeV of the LES and a mixed isoscalar/isovector toroidal/compression flow in the higher bin 8.8-10.5 MeV. Thus the modes covered by LES embrace both vortical and irrotational motion. The simple collective picture of the LES as a "pygmy" mode (oscillations of the neutron excess against the nuclear core) is not confirmed.

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Analysis of the neutron and proton contributions to the pygmy dipole mode in doubly magic nuclei

Cited by 31 publications

References 53 publications

Multipole excitations in hot nuclei within the finite temperature quasiparticle random phase approximation framework

Multipole excitations in hot nuclei within the finite temperature quasiparticle random phase approximation framework

Pygmy dipole resonance in208Pb

Toroidal nature of the low-energyE1mode

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