1,721,042 research outputs found
Mean field and beyond in nuclei far from stability lines
No full textWe calculate, for the first time, the state-dependent pairing gap of a finite nucleus (120Sn) diagonalizing the bare nucleon-nucleon potential (Argonne v14) in a Hartree-Fock basis. The resulting gap accounts for about half of the experimental gap. Going beyond the mean field in the particle-particle channel, the combined effect of the bare nucleon-nucleon potential and of the induced pairing interaction arising from the exchange of low-lying surface vibrations between nucleons moving in time reversal states close to the Fermi energy accounts for the experimental gap. Examples for light, halo nuclei are also reported. The more studied effects of the particle-vibration coupling in the particle-hole channel are discussed for the low-lying quadrupole vibration in 120Sn and the giant dipole resonance in the unstable oxygen isotopes and 132Sn
Effects of the tensor force on the multipole response in finite nuclei
No full textWe present a thorough analysis of the effects of tensor interaction on the multipole response of magic nuclei, using the fully self-consistent random phase approximation model with Skyrme interactions. We disentangle the modifications to the static mean field induced by the tensor terms, and the specific features of the residual particle-hole (p-h) tensor interaction, for quadrupole (2+), octupole (3-), and also magnetic dipole (1+) responses. It is pointed out that the tensor force has a larger effect on the magnetic dipole states than on the natural parity states 2+ and 3-, especially at the mean-field level. Perspectives for a better assessment of the tensor force parameters are discussed
Tensor correlations and evolution of single-particle energies in medium-mass nuclei
No full textWe analyze the evolution of the spin-orbit splittings in the Ca isotopes and in the N=28 isotones. We also focus on the reduction of the spin-orbit splittings associated with f and p orbits from Ca-48 to Ar-46. We conclude that adding the tensor contribution can qualitatively explain in most cases the empirical trends, whereas this is not the case if one simply employs existing Skyrme parametrizations without the tensor force
Binding energies and medium polarization effects
No full textThere exist several effective interactions whose parameters are fitted to force mean field predictions to reproduce experimental observables in finite nuclei and calculated properties of infinite nuclear matter. Exploiting this technique, one can give a good description of nuclear binding energies. We present evidence that further progress can be made by taking into account medium polarization effects associated with surface and pairing vibrations
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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