1,721,044 research outputs found
Sum rules of the multiple giant resonance states
No full textVarious sum rules for multiple giant dipole resonance states are derived. For the triple giant dipole resonance states, the energy-weighted sum of the transition strengths requires a model to be related to those of the single and double giant dipole resonance states. It is also shown that the non-diagonal matrix elements of the double commutator between the dipole operator and the nuclear Hamiltonian give useful identities for the excitation energy and transition strength of each excited state. Using those identities, the relationship between width of the single dipole state and those of the multiple ones is qualitatively discussed. These results, it is stressed, may be useful in the study of other systems than dipole excitations in nuclei, as well as in the problem of anharmonicities of collective motions
Nonrelativistic nuclear energy functionals
No full textIn the present volume, several lectures are devoted to the implementations of the Density Functional Theory (DFT) in atomic nuclei, either in the non-relativistic or covariant formalism. By restricting ourselves to the non-relativistic case, in this contribution we deal with two aspects of the theory: firstly, its time-dependent extension and the study of the nuclear vibrational excitations, and secondly, the use of effective interactions beyond the mean field framework. Few recent applications, involving both stable and unstable nuclei, are presented
Microscopic theory of the γ decay of nuclear giant resonances
No full textIn the past decades, the γ decay of giant resonances has been studied using phenomenological models. In keeping with possible future studies performed with exotic beams, microscopically based frameworks should be envisaged. In the present paper, we introduce a model which is entirely based on Skyrme effective interactions, and treats the ground-state decay within the fully self-consistent random phase approximation (RPA) and the decay to low-lying states at the lowest order beyond RPA. The model is applied to 208Pb and 90Zr, and the results are compared with the experimental data
Dipole states in stable and unstable nuclei
No full textA nuclear structure model based on linear response theory (i.e., random phase approximation) and which includes pairing
correlations and anharmonicities (coupling with collective vibrations), has been implemented in such a way that it can be applied
on the same footing to magic as well as open-shell nuclei. As applications, we have chosen to study the dipole excitations both
in well known, stable isotopes like 208Pb and 120Sn as well as in the neutron-rich, unstable 132Sn nucleus, by addressing in the
latter case the question about the nature of the low-lying strength. Our results suggest that the model is reliable and predicts in
all cases low-lying strength of non collective nature
Hybrid configuration mixing model for odd nuclei
Full text linkIn this work, we introduce a new approach which is meant to be a first step towards complete self-consistent low-lying spectroscopy of odd nuclei. So far, we essentially limit ourselves to the description of a double-magic core plus an extra nucleon. The model does not contain any free adjustable parameter and is instead based on a Hartree-Fock (HF) description of the particle states in the core, together with self-consistent random-phase approximation (RPA) calculations for the core excitations. We include both collective and noncollective excitations, with proper care of the corrections due to the overlap between them (i.e., due to the nonorthonormality of the basis). As a consequence, with respect to traditional particle-vibration coupling calculations in which one can only address single-nucleon states and particle-vibration multiplets, we can also describe states of shell-model types like 2 particle-1 hole. We will report results for Ca49 and Sb133 and discuss future perspectives
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