986 resultados para SUPERHEAVY NUCLEI


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Binding energy differences of mirror nuclei for A = 15, 17, 27, 29, 31, 33, 39 and 41 are calculated in the framework of relativistic deformed mean-field theory. To fully include the effects of the polarization of the nuclear core due to the extra particle or hole, the spatial components of the vector meson fields and the photon are taken into account in a self-consistent manner. The calculated binding energy differences are systematically smaller than the experimental values and lend support to the existency of the Okamoto-Nolen-Schiffer anomaly found decades ago in nonrelativistic calculations, For the majority of the nuclei studied, however, the results are such that the anomaly is significantly smaller than the one obtained within state-of-the-art nonrelativistic calculations.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The parametric region in the plane defined by the ratios of the energies of the subsystems and the three-body ground state, in which Efimov states can exist, is determined. We use a renormalizable model that guarantees the general validity of our results in the context of short-range interactions. The experimental data for one-and two-neutron separation energies, implies that among the halo nuclei candidates, only 20C has a possible Efimov state, with an estimated energy less than 14 KeV below the scattering threshold.

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We perform a self-consistent relativistic RPA calculation for the isobaric analogue and Gamow-Teller resonances based on relativistic mean field theory results for the ground states of 48Ca, 90Zr and 208Pb. We use the parameter set NL1 for the σ, ω and ρ mesons, and experimental values for the pion and nucleon. An extra parameter, related to the intensity of the contact term in the pion-exchange interaction, is crucial to reproduce the latter resonances. © 1998 Published by Elsevier Science B.V. All rights reserved.

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It is shown that three-body non-Borromean halo nuclei like 12Be, 18C, 20C, considered as neutron-neutron-core systems, have p-wave virtual states with energy of about 1.7 times the corresponding neutron-core binding energy. We use a renormalizable model that guarantees the general validity of our results in the context of short range interactions.

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In the present work, nano-sized magnetic nuclei of Co have been electrodeposited onto p-Si (111). The deposition follows a mechanism of progressive nucleation and growth controlled by diffusion. MFM studies showed that the transition between magnetic domain states is strongly dependent on the size and shape of the nuclei. A critical height h0 is defined below which the nuclei presented always a single-domain configuration. The limiting lower boundary for the single-domain state calculated from the theory is quantitatively coincident with the experimental results. © 2004 Elsevier B.V. All rights reserved.

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For light exotic nuclei modeled as two neutrons n and a core A, we report results for the two-neutron correlation functions and also for the mean-square radii, considering a universal scaling function. The results of our calculations for the neutron-neutron correlation functions are qualitatively consistent with recent data obtained for 11Li and 14Be nuclei. The root-mean-square distance in the halo of such nuclei are also consistent with data, which means that the neutrons of the halo have a large probability to be found outside the interaction range. Therefore the low-energy properties of these halo neutrons are, to a large extend, model independent as long as few physical input scales are fixed. The model is restricted to s-wave subsystems, with small energies for the bound or virtual states. For the radii we are also shown results for the 6He and 20C. All the interaction effects, as higher partial wave in the interaction and/or Pauli blocking effect are, to some extend, included in our model, as long as the three-body binding energy is supplied. © 2005 American Institute of Physics.

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We analyze the surface geometry of the spherical even-even Ca, Ni, Sn and Pb nuclei using two approaches: The relativistic Dirac-Hartree-Bogoliubov one with several parameter sets and the non-relativistic Hartree-Fock-Bogoliubov one with the Gogny force. The proton and neutron density distributions are fitted to two-parameter Fermi density distributions to obtain the half-density radii and diffuseness parameters. Those parameters allow us to determine the nature of the neutron skins predicted by the models. The calculations are compared with existing experimental data. © 2007 American Institute of Physics.

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We report a renormalized zero-range interaction approach to estimate the size of generic weakly bound three-body systems where two particles are identical. We present results for the neutron-neutron root-mean-square distances of the halo nuclei 6He, 11Li, 14Be and 20C, where the systems are taken as two halo neutrons with an inert point-like core. We also report an approach to obtain the neutron-neutron correlation function in halo nuclei. In this case, our results suggest a review of the corresponding experimental data analysis. © 2007 American Institute of Physics.

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We present results for spatial distributions of weakly-bound three-body systems, derived from a universal scaling function that depends on the mass ratio of the particles, as well as on the nature of the subsystems. © 2007 American Institute of Physics.

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In this contribution I provide an overview of our group papers involving universalities in light exotic nuclei. It is also made a connection of these systems with some weakly bound ultracold molecules. © 2010 American Institute of Physics.

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Within general characteristics of low-energy few-body systems, we revise some well-known correlations found in nuclear physics, and the properties of low-mass halo nuclei in a three-body neutron-neutron-core model. In this context, near the critical conditions for the occurrence of an Efimov state, we report some results obtained for the neutron- 19C elastic scattering. © 2010 American Institute of Physics.