摘要 :
The farthest reaching interpretation of a light nuclear system in terms of the Nilsson-model is obtained for A = 26. The T = 1 and T = 0 levels of either parity in Mg-26 and/or Al-26 are shown to be grouped in more than 35 rotatio...
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The farthest reaching interpretation of a light nuclear system in terms of the Nilsson-model is obtained for A = 26. The T = 1 and T = 0 levels of either parity in Mg-26 and/or Al-26 are shown to be grouped in more than 35 rotational bands together containing some 55 levels in Mg-26 and 170 in Al-26. The Nilsson-model configurations and deformations of bands are deduced from measured spectroscopic factors and electromagnetic transition rates. The experimental data are amended by shell-model calculations in the complete s-d basis space based on the universal s-d Hamiltonian. The rotational structure of positive-parity states is complexely contained in the shell-model results. The Nilsson diagram gives a natural explanation of all bands. An important facet is the observation of particle-hole configurations with large K which arise from the complete alignment of particle and hole angular momenta along the major axis of deformation. (C) 1998 Elsevier Science B.V. [References: 42]
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The angular momentum projection for the axially deformed Nilsson mean-field plus a modified standard pairing (MSP) or the nearest-level pairing (NLP) model is proposed. Both the exact projection, in which all intrinsic states are ...
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The angular momentum projection for the axially deformed Nilsson mean-field plus a modified standard pairing (MSP) or the nearest-level pairing (NLP) model is proposed. Both the exact projection, in which all intrinsic states are taken into consideration, and the approximate projection, in which only intrinsic states with K = 0 are taken in the projection, are considered. The analysis shows that the approximate projection with only K = 0 intrinsic states seems reasonable, of which the configuration subspace considered is greatly reduced. As simple examples for the model application, low-lying spectra and electromagnetic properties of O-18 and Ne-18 are described by using both the exact and approximate angular momentum projection of the MSP or the NLP, while those of Ne-20 and Mg-24 are described by using the approximate angular momentum projection of the MSP or NLP. (C) 2016 Elsevier B.V. All rights reserved.
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The interbasis expansion of deformed cylindrical 3D harmonic oscillator (HO) wavefunctions in terms of spherical wavefunction bases is introduced. The spatial overlap integral is rewritten in a simplified form and presented in ter...
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The interbasis expansion of deformed cylindrical 3D harmonic oscillator (HO) wavefunctions in terms of spherical wavefunction bases is introduced. The spatial overlap integral is rewritten in a simplified form and presented in terms of the axis ratio of the deformed nucleus. Deformed nuclear spheroidal shapes are considered, including both quadrupole and hexadecapole deformations. The effect of deformation on the oscillator lengths of deformed 3D-HO, and in turn on the spatial overlap coefficients, is discussed. For the description of the geometrical shape of deformed nuclear systems, the collective and extended Nilsson models for surface parametrization are used.
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The Po isotopes show the presence of coexisting structures having different deformations with increasing neutron number within the macroscopic-microscopic Nilsson-Strutinsky formalism. The model is based on the Lublin Strasbourg D...
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The Po isotopes show the presence of coexisting structures having different deformations with increasing neutron number within the macroscopic-microscopic Nilsson-Strutinsky formalism. The model is based on the Lublin Strasbourg Drop (LSD) method for the macroscopic energy calculation. We study the shape evolution in a long chain of polonium isotopes, Po178-200.
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The spectroscopic amplitudes of the virtual decays of silicon isotopes 28(30) Si(JB) p(t) + 27A1(JA) have been obtained using the wave functions of the ld-2s-shell nuclei in the Nilsson model. It has been shown that correct spectr...
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The spectroscopic amplitudes of the virtual decays of silicon isotopes 28(30) Si(JB) p(t) + 27A1(JA) have been obtained using the wave functions of the ld-2s-shell nuclei in the Nilsson model. It has been shown that correct spectroscopy of the ld-2s-shell nuclei and consideration of their deformation has a significant effect on the values and signs of the spectroscopic amplitudes of both protons and tritons.
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The potential energy surfaces of the isotopes of Kr, Rb, Sr and Zr and the isotones N = 40 in the A similar to 80 region of the nuclear landscape display interesting shape variations with N and Z. The shape evolution and the possi...
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The potential energy surfaces of the isotopes of Kr, Rb, Sr and Zr and the isotones N = 40 in the A similar to 80 region of the nuclear landscape display interesting shape variations with N and Z. The shape evolution and the possible shape coexistence are discussed within the cranked Nilsson-Strutinsky (CNS) framework for the isotopic and isotonic chains. The results indicate an oblate shell gap at Z = 36 and 37 and a prolate shell gap at Z = 38 and 40 with deformation epsilon(2) similar to 0.4. Our calculations show a well deformed prolate shell gap at N = 40 so that it is determinant in the nuclear shape in this mass region. (C) 2019 Elsevier B.V. All rights reserved.
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We study the shape evolution of the fission barrier of the actinide isotopes with increasing the neutron number, and also the angular momentum. The calculations are based on the macroscopic Lublin-Strasbourg Drop model. We calcula...
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We study the shape evolution of the fission barrier of the actinide isotopes with increasing the neutron number, and also the angular momentum. The calculations are based on the macroscopic Lublin-Strasbourg Drop model. We calculate the potential energy surfaces in three-dimensional deformation space spanned by (epsilon(2), gamma, epsilon(4)) in the perturbed-spheroid parametrization of the unpaired cranked Nilsson model at different angular momenta. The macroscopic-microscopic calculations show a double-humped barrier with three minimafor nuclei with A < 255. For heavy actinides, the number of humps in the fission barrier drops to one with increasing neutron number. General trends of the evolution of the fission barrier heights are discussed as a function of spin. We find that the fission barrier decreases with increasing the angular momentum for the isotopes in this mass region. (C) 2020 Elsevier B.V. All rights reserved.
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The microscopic origins and the current predictions of the proxy-SU(3) symmetry model of atomic nuclei were reviewed. Beginning with experimental evidence for the special roles played by nucleon pairs with maximal spatial overlap,...
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The microscopic origins and the current predictions of the proxy-SU(3) symmetry model of atomic nuclei were reviewed. Beginning with experimental evidence for the special roles played by nucleon pairs with maximal spatial overlap, the proxy-SU(3) approximation scheme is introduced; its validity is demonstrated through Nilsson model calculations and its connection to the spherical shell model. The major role played by the highest weight-irreducible representations of SU(3) in shaping up the nuclear properties is pointed out, resulting in parameter-free predictions of the collective variables β and γ for even-even nuclei in the explanation of the dominance of prolate over oblate shapes in the ground states of even-even nuclei, in the prediction of a shape/phase transition from prolate to oblate shapes below closed shells, and in the prediction of specific islands on the nuclear chart in which shape coexistence is confined. Further developments within the proxy-SU(3) scheme are outlined.
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Effect of the nuclear hexacontatetrapole deformation on the rotational structure of Er-158 is analyzed using the Cranked Nilsson-Strutinsky (CNS) approach. Our calculations show that it will lead to a decrease of the total energy ...
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Effect of the nuclear hexacontatetrapole deformation on the rotational structure of Er-158 is analyzed using the Cranked Nilsson-Strutinsky (CNS) approach. Our calculations show that it will lead to a decrease of the total energy of similar to 700 keV in the strongly deformed (SD) region and only a few keV in the triaxial superdeformed (TSD) region. Therefore, it is concluded that the effect of the hexacontatetrapole deformation is significant for SD shapes and essentially negligible for TSD shapes.
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Deformed single particle energies obtained by averaging a particle– core Hamiltonian with a projected spherical basis depend on a deformation parameter and an arbitrary constant defining the canonical transformation relating the ...
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Deformed single particle energies obtained by averaging a particle– core Hamiltonian with a projected spherical basis depend on a deformation parameter and an arbitrary constant defining the canonical transformation relating the collective quadrupole coordinates and momenta with the boson operators. When the mentioned basis describes the single particle motion of either protons or neutrons the parameters involved are isospin dependent. An algorithm for fixing these parameters is formulated and then applied for 194 isotopes covering a good part of the nuclide chart. Relation with the Nilsson deformed basis is pointed out in terms of deformation dependence of the corresponding single particle energies as well as of the nucleon densities and their symmetries. The proposed projected spherical basis provides an efficient tool for the description of spherical and deformed nuclei in a unified fashion.
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