We discuss the predictions of the large scale calculations using the re-alistic realisation of th... more We discuss the predictions of the large scale calculations using the re-alistic realisation of the phenomenological nuclear mean-field theory. Calculations indicate that certain Zirconium nuclei are tetrahedral-symmetric in their ground-states. After a short overview of the re-search of the nuclear tetrahedral symmetry in the past we analyse the predictive capacities of the method and focus on the 96Zr nucleus expected to be tetrahedral in its ground-state.
The high-energy and discrete gamma-ray spectra, as well as the charged particle angular distribut... more The high-energy and discrete gamma-ray spectra, as well as the charged particle angular distribution have been measured in the reaction 105 MeV 18O+28Si using the EUROBALL IV, HECTOR and EUCLIDES arrays in order to investigate the predicted Jacobi shape transition in light nuclei. A comparison of the GDR line shape data with the predictions of the thermal shape fluctuation model, based on the most recent rotating liquid drop LSD calculations, shows evidence for such Jacobi shape transition in hot, rapidly rotating 46Ti. The found narrow low-energy component in the GDR line shape is interpreted as the consequence both of the elongated shape and of the Coriolis effect.
Une des applications récentes des méthodes de champ moyen en physique nucléaire est l'étude d... more Une des applications récentes des méthodes de champ moyen en physique nucléaire est l'étude des symétries exotiques du noyau. Cette problématique est reliée, en particulier, à l'ánalyse de la rotation nucléaire autour d'un axe incliné par rapport aux axes principaux de la distribution de masse dans le modèle dit de Tilted-Axis Cranking (TAC). Cette thèse présente l'un des premiers calculs TAC effectués dans le cadre de méthodes entièrement auto-cohérentes. La méthode Hartree-Fock avec l'interaction effective à deux corps de Skyrme a été utilisée. Un code numérique a été écrit qui permet de briser toutes les symétries spatiales des solutions. Comme première application, des calculs pour les bandes magnétiques dans 142Gd et pour les bandes chirales dans 130Cs, 132La, 134Pr et 136Pm ont été effectués. L'existence de ces bandes est dûe à un nouveau mécanisme de brisure de la symétrie sphérique, et de brisure spontanée de la symétrie chirale, respectivement. Les s...
IFT preprint 19/2004 Chiral and magnetic rotation in atomic nuclei studied within self-consistent... more IFT preprint 19/2004 Chiral and magnetic rotation in atomic nuclei studied within self-consistent mean-field methods
We consider many-body E-l transition matrix-elements between two nuclear states of different axia... more We consider many-body E-l transition matrix-elements between two nuclear states of different axially-symmetric deformations characterised by two different (mutually non-orthogonal) sets of single-particle wave-functions. Yet, when varying the deformations of the initial, final, or both these states one notices abrupt changes in the form of vanishing and possibly reappearance of the transition matrix elements calculated between the corresponding Slater determinants. The mechanism is explained in terms of the conservation of the |m| quantum number (absolute value of the projection of individual-nucleonic angular-momenta); consequences for the more general calculations of this type also without axial symmetry are discussed.
Structure of symmetrization group and its influence on symmetries in the intrinsic frame for coll... more Structure of symmetrization group and its influence on symmetries in the intrinsic frame for collective nuclear models is analysed.
In this paper we formulate and discuss the strategy of constructing theories capable of providing... more In this paper we formulate and discuss the strategy of constructing theories capable of providing not only the numerical predictions sensu stricto but also the distributions of probability that such predictions apply in the predefined physics context. Examples of applications of the presented ideas are illustrated using as a choice the nuclear mean-field theory with two realistic realizations of the underlying Hamiltonians: Phenomenological Woods–Saxon and self-consistent Skyrme–Hartree–Fock.
The macroscopic-microscopic method is applied to calculate the energies of heavy nuclei (A>220... more The macroscopic-microscopic method is applied to calculate the energies of heavy nuclei (A>220) in a multidimensional deformation space {αλ,μ} including axial and non-axial quadrupole (λ=2,μ=0,2), axial and non-axial octupole (λ=3,μ=0,2) and axial hexadecapole (λ=4,μ=0) degrees of freedom. Shell and pairing corrections are calculated from the single-particle energies of the Woods-Saxon potential with the universal parameters and added to the macroscopic energy of the newest Lublin-Strasbourg Drop (LSD) model to obtain the total deformation energy.
Calculations using realistic mean-field methods suggest the existence of nuclear shapes with tetr... more Calculations using realistic mean-field methods suggest the existence of nuclear shapes with tetrahedral Td and/or octahedral Oh symmetries sometimes at only a few hundreds of keV above the ground states in some rare earth nuclei around 156Gd and 160Yb. The underlying single-particle spectra manifest exotic fourfold rather than Kramers's twofold degeneracies. The associated shell gaps are very strong, leading to a new form of shape coexistence in many rare earth nuclei. We present possible experimental evidence of the new symmetries based on the published experimental results--although an unambiguous confirmation will require dedicated experiments.
We discuss the predictions of the large scale calculations using the re-alistic realisation of th... more We discuss the predictions of the large scale calculations using the re-alistic realisation of the phenomenological nuclear mean-field theory. Calculations indicate that certain Zirconium nuclei are tetrahedral-symmetric in their ground-states. After a short overview of the re-search of the nuclear tetrahedral symmetry in the past we analyse the predictive capacities of the method and focus on the 96Zr nucleus expected to be tetrahedral in its ground-state.
The high-energy and discrete gamma-ray spectra, as well as the charged particle angular distribut... more The high-energy and discrete gamma-ray spectra, as well as the charged particle angular distribution have been measured in the reaction 105 MeV 18O+28Si using the EUROBALL IV, HECTOR and EUCLIDES arrays in order to investigate the predicted Jacobi shape transition in light nuclei. A comparison of the GDR line shape data with the predictions of the thermal shape fluctuation model, based on the most recent rotating liquid drop LSD calculations, shows evidence for such Jacobi shape transition in hot, rapidly rotating 46Ti. The found narrow low-energy component in the GDR line shape is interpreted as the consequence both of the elongated shape and of the Coriolis effect.
Une des applications récentes des méthodes de champ moyen en physique nucléaire est l'étude d... more Une des applications récentes des méthodes de champ moyen en physique nucléaire est l'étude des symétries exotiques du noyau. Cette problématique est reliée, en particulier, à l'ánalyse de la rotation nucléaire autour d'un axe incliné par rapport aux axes principaux de la distribution de masse dans le modèle dit de Tilted-Axis Cranking (TAC). Cette thèse présente l'un des premiers calculs TAC effectués dans le cadre de méthodes entièrement auto-cohérentes. La méthode Hartree-Fock avec l'interaction effective à deux corps de Skyrme a été utilisée. Un code numérique a été écrit qui permet de briser toutes les symétries spatiales des solutions. Comme première application, des calculs pour les bandes magnétiques dans 142Gd et pour les bandes chirales dans 130Cs, 132La, 134Pr et 136Pm ont été effectués. L'existence de ces bandes est dûe à un nouveau mécanisme de brisure de la symétrie sphérique, et de brisure spontanée de la symétrie chirale, respectivement. Les s...
IFT preprint 19/2004 Chiral and magnetic rotation in atomic nuclei studied within self-consistent... more IFT preprint 19/2004 Chiral and magnetic rotation in atomic nuclei studied within self-consistent mean-field methods
We consider many-body E-l transition matrix-elements between two nuclear states of different axia... more We consider many-body E-l transition matrix-elements between two nuclear states of different axially-symmetric deformations characterised by two different (mutually non-orthogonal) sets of single-particle wave-functions. Yet, when varying the deformations of the initial, final, or both these states one notices abrupt changes in the form of vanishing and possibly reappearance of the transition matrix elements calculated between the corresponding Slater determinants. The mechanism is explained in terms of the conservation of the |m| quantum number (absolute value of the projection of individual-nucleonic angular-momenta); consequences for the more general calculations of this type also without axial symmetry are discussed.
Structure of symmetrization group and its influence on symmetries in the intrinsic frame for coll... more Structure of symmetrization group and its influence on symmetries in the intrinsic frame for collective nuclear models is analysed.
In this paper we formulate and discuss the strategy of constructing theories capable of providing... more In this paper we formulate and discuss the strategy of constructing theories capable of providing not only the numerical predictions sensu stricto but also the distributions of probability that such predictions apply in the predefined physics context. Examples of applications of the presented ideas are illustrated using as a choice the nuclear mean-field theory with two realistic realizations of the underlying Hamiltonians: Phenomenological Woods–Saxon and self-consistent Skyrme–Hartree–Fock.
The macroscopic-microscopic method is applied to calculate the energies of heavy nuclei (A>220... more The macroscopic-microscopic method is applied to calculate the energies of heavy nuclei (A>220) in a multidimensional deformation space {αλ,μ} including axial and non-axial quadrupole (λ=2,μ=0,2), axial and non-axial octupole (λ=3,μ=0,2) and axial hexadecapole (λ=4,μ=0) degrees of freedom. Shell and pairing corrections are calculated from the single-particle energies of the Woods-Saxon potential with the universal parameters and added to the macroscopic energy of the newest Lublin-Strasbourg Drop (LSD) model to obtain the total deformation energy.
Calculations using realistic mean-field methods suggest the existence of nuclear shapes with tetr... more Calculations using realistic mean-field methods suggest the existence of nuclear shapes with tetrahedral Td and/or octahedral Oh symmetries sometimes at only a few hundreds of keV above the ground states in some rare earth nuclei around 156Gd and 160Yb. The underlying single-particle spectra manifest exotic fourfold rather than Kramers's twofold degeneracies. The associated shell gaps are very strong, leading to a new form of shape coexistence in many rare earth nuclei. We present possible experimental evidence of the new symmetries based on the published experimental results--although an unambiguous confirmation will require dedicated experiments.
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