Multiphonon excitations and pygmy resonances in tin isotopes

Lanza, E. G.; Catara, F.; Gambacurta, D.; Andrés, M. V.; Chomaz, Ph.

doi:10.1103/physrevc.79.054615

Cited by 55 publications

(64 citation statements)

References 40 publications

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“…in Refs. [40,41]. Alternative information on the PDR structure may be obtained from isoscalar probes [42,43] as demonstrated by studies of the (α, α ′ γ) reaction [21,44].…”

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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“…in Refs. [40,41]. Alternative information on the PDR structure may be obtained from isoscalar probes [42,43] as demonstrated by studies of the (α, α ′ γ) reaction [21,44].…”

Section: Excitation Ofmentioning

confidence: 99%

Pygmy dipole resonance in208Pb

et al. 2012

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“…Recently, this analysis was performed for some tin isotopes within the QRPA approach [5,58,60] and within the relativistic QTBA [54]. In Fig.…”

Section: -6mentioning

confidence: 99%

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

Авдеенков

Goriely²,

Kamerdzhiev

et al. 2011

Phys. Rev. C

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The E1 strength function for 15 stable and unstable Sn even-even isotopes from A = 100 to A = 176 are calculated using a self-consistent microscopic theory which, in addition to the standard (quasiparticle) randomphase approximation [(Q)RPA] approach, takes into account phonon coupling and the single-particle continuum (by means of the discretization procedure) with a cutoff of 100 MeV. 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 β-stability valley. We show that the inclusion of 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 γ -ray-strength function for astrophysics applications. In particular, such calculations are highly recommended for a reliable estimate of the electromagnetic properties of exotic nuclei.

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“…Finally, SRPA would allow to study in a proper way the double phonon excitation modes that are experimentally well known in nuclei [23] and have been the object of several theoretical analysis: most of these studies have been so far based on boson mapping procedures which, however, require high order expansions in order to take into account the corrections due to the Pauli principle (see Ref. [24] and references therein). In all these cases, interesting results may be expected by the application of SRPA including all kinds of coupling between 1p1h and 2p2h elementary excitations.…”

Section: Introductionmentioning

confidence: 99%

Collective nuclear excitations with Skyrme-second random-phase approximation

2010

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Second RPA calculations with a Skyrme force are performed to describe both high-and low-lying excited states in 16 O. The coupling between 1 particle-1 hole and 2 particle-2 hole as well as that between 2 particle-2 hole configurations among themselves are fully taken into account and the residual interaction is never neglected, not resorting therefore to a generally used approximate scheme where only the first kind of coupling is considered. The issue of the rearrangement terms in the matrix elements beyond standard RPA is addressed and discussed. As a general feature of second RPA results, a several-MeV shift of the strength distribution to lower energies is systematically found with respect to RPA distributions. A much more important fragmentation of the strength is also naturally provided by second RPA due to the huge number of 2 particle-2 hole configurations.A better description of the excitation energies of the low-lying 0 + and 2 + states is obtained with second RPA with respect to RPA.

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Multiphonon excitations and pygmy resonances in tin isotopes

Cited by 55 publications

References 40 publications

Pygmy dipole resonance in208Pb

Pygmy dipole resonance in208Pb

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

Collective nuclear excitations with Skyrme-second random-phase approximation

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