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The potential-energy surfaces of even-even super-heavy nuclei are evaluated within the LSD macroscopic-microscopic approach with a Yukawafolded mean-field potential using the Fourier shape parametrization. The calculations are performed in a four-dimensional deformation space, defined by quadrupole, octupole, hexadecapole and nonaxiality degrees of freedom. It is shown that the both pear-like and nonaxial deformation modes are important when evaluating fission barrier heights. [ABSTRACT FROM AUTHOR]

To evaluate the influence of the blood–brain barrier on neuronal gadolinium deposition in a mouse model after multiple intravenous applications of the linear contrast agent gadodiamide. The prospective study held 54 mice divided into three groups: healthy mice (A), mice with iatrogenic induced disturbance of the blood–brain barrier by glioblastoma (B) or cerebral infarction (C). In each group 9 animals received 10 iv-injections of gadodiamide (1.2 mmol/kg) every 48 h followed by plain T1-weighted brain MRI. A final MRI was performed 5 days after the last contrast injection. Remaining mice underwent MRI in the same time intervals without contrast application (control group). Signal intensities of thalamus, pallidum, pons, dentate nucleus, and globus pallidus-to-thalamus and dentate nucleus-to-pons ratios, were determined. Gadodiamide complex and total gadolinium amount were quantified after the last MR examination via LC–MS/MS and ICP-MS. Dentate nucleus-to-pons and globus pallidus-to-thalamus SI ratios showed no significant increase over time within all mice groups receiving gadodiamide, as well as compared to the control groups at last MR examination. Comparing healthy mice with group B and C after repetitive contrast administration, a significant SI increase could only be detected for glioblastoma mice in globus pallidus-to-thalamus ratio (p = 0.033), infarction mice showed no significant SI alteration. Tissue analysis revealed significantly higher gadolinium levels in glioblastoma group compared to healthy (p = 0.013) and infarction mice (p = 0.029). Multiple application of the linear contrast agent gadodiamide leads to cerebral gadolinium deposition without imaging correlate in MRI. [ABSTRACT FROM AUTHOR]

The recently developed extremely flexible and rapidly converging Fourier shape parametrisation is used to evaluate the potential energy surfaces of 210Th-238Th even-even isotopes within the macroscopic-microscopic method. A vast sample of 4D landscapes is analysed, searching for absolute and local extrema, ridges and valleys. The expected fission-fragment mass distribution obtained from different Th isotopes at low excitation energy is illustrated by a static analysis of the potential energy landscape. Quadrupole moments in the relevant minima are also evaluated. [ABSTRACT FROM AUTHOR]

The extended Gutzwiller trajectory approach is presented for the semiclassical description of nuclear collective dynamics, in line with the main topics of the fruitful activity of V.G. Solovjov. Within the Fermi-liquid droplet model, the leptodermous effective surface approximation was applied to calculations of energies, sum rules, and transition densities for the neutron-proton asymmetry of the isovector giant-dipole resonance and found to be in good agreement with the experimental data. By using the Strutinsky shell correctionmethod, the semiclassical collective transport coefficients, such as nuclear inertia, friction, stiffness, and moments of inertia, can be derived beyond the quantum perturbation approximation of the response function theory and the cranking model. The averaged particle-number dependences of the low-lying collective vibrational states are described in good agreement with the basic experimental data, mainly due to the enhancement of the collective inertia as compared to its irrotational flow value. Shell components of the moment of inertia are derived in terms of the periodic-orbit free-energy shell corrections. A good agreement between the semiclassical extended Thomas-Fermi moments of inertia with shell corrections and the quantum results is obtained for different nuclear deformations and particle numbers. Shell effects are shown to be exponentially dampted out with increasing temperature in all the transport coefficients. [ABSTRACT FROM AUTHOR]

Using the macroscopic-microscopic approach with the macroscopic energy determined by the Lublin-Strasbourg Drop model and the microscopic, shell plus pairing, corrections evaluated through the Yukawa-folded mean-field potential, a certain number of yet unknown super- and hyperdeformed shape isomers in even-even Po, Ra and Th isotopes are predicted. Quadrupole moments and the energies of the lowest rotational state 2+ in the local minima of the potential-energy surfaces are evaluated. We show that they turn out to be in good agreement with the available experimental data for the ground state. [ABSTRACT FROM AUTHOR]

The quasiparticle Landau Fermi-liquid and periodic orbit theories are presented for the semi-classical description of collective excitations in nuclei, which are close to one of the main topics of the fruitful activity of S.T. Belyaev. Density-density response functions are studied at low temperatures within the temperature-dependent collisional Fermi-liquid theory in the relaxation time approximation. The isothermal, isolated (static) and adiabatic susceptibilities for nuclear matter show the ergodicity property. Temperature corrections to the response function, viscosity and thermal conductivity coefficients have been derived, also in the long wavelength (hydrodynamic) limit. The relaxation and correlation functions are obtained through the fluctuation-dissipation theorem and their properties are discussed in connection to the static susceptibilities and ergodicity of the Fermi systems. Transport coefficients, such as nuclear friction and inertia as functions of the temperature for the hydrodynamic (heat-pole and first sound) and Fermi surface distortion zero-sound modes are derived within the Fermi-liquid droplet model. They are shown to be in agreement with the semi-microscopical calculations based on the nuclear shell model (SM) for large temperatures. This kinetic approach is extended to the study of the neutron-proton correlations in asymmetric neutron-rich nuclei. The surface symmetry binding-energy constants are presented as functions of the Skyrme-force parameters in the approximation of a sharp-edged proton-neutron asymmetric nucleus and applied to calculations of the isovector giant dipole resonance. The energies, sum rules, and transition densities of these resonances obtained by using analytical expression for these surface constants in terms of the Skyrme-force parameters are in fairly good agreement with the experimental data. An analysis of the experimental data, in particular the specific structure of these resonances in terms of a main, and some satellite peaks, in comparison with our analytical approach and other theoretical semimicroscopical models, might turn out to be of capital importance for a better understanding of the values of the fundamental surface symmetry-energy constant. The semiclassical collective moment of inertia is derived analytically beyond the quantum perturbation approximation of the cranking model for any potential well as a mean field. It is shown that this moment of inertia can be approximated by its rigid-body value for the rotation with a given frequency within the ETF and more general periodic orbit theories in the nearly local long-length approximation. Its semiclassical shell-structure components are derived in terms of the periodic-orbit free-energy shell corrections. An enhancement of the moment of inertia near the symmetrybreaking bifurcation deformations was found. We obtained good agreement between the semiclassical and quantum shell-structure components of the moment of inertia for several critical bifurcation deformations for the completely analytically solved example of the harmonic oscillator mean field. [ABSTRACT FROM AUTHOR]

We discuss the relevance of the single-particle (sp) properties of the well studied Skyrme SIII interaction to describe some spectroscopic properties of heavy nuclei within self-consistent Hartree-Fock plus BCS calculations (with blocking when needed), using a simple seniority pairing residual interaction (Vres). To fit Vres we took stock of the excellent consistency found in the rare-earth region between its adjustment to both moments of inertia (MoI) of well-deformed nuclei and oddeven mass differences. For simplicity reasons we thus made a fit on MoI. Our sample of nuclei was defined by all even-even isotopes of actinide and heavier elements, with two criteria: i) be well and rigidly deformed in their ground states, as assessed by a ratio E(4+1)=E(2+1) > 3:2, ii) present some isomeric activity with suggested isomeric energy (EIS) and spin/parity characterization. We have thus considered 14 actinide isotopes (from Uranium to Nobelium) plus 256Rf. With a simple law of variation of the pairing matrix elements according to N or Z, we get a fair reproduction of MoI except around the neutron number N = 152 where SIII exaggerates its well documented magicity (for normally deformed solutions). Such a study of MoI assesses thus also the sp spectra, of which a further evaluation of the quality is provided by the comparison of the corresponding experimental and theoretical EIS. Our calculations were limited to quasi-particle (uncoupled) configuration of the seniority 2 type. Preliminary results on some isomeric states of the considered isotopes will be discussed particularly by comparing them with those obtained in a particle number conserving approach. [ABSTRACT FROM AUTHOR]

Deformation-energy surfaces of 54 even-even isotopes of Pt, Hg and Pb nuclei with neutron numbers up to 126 are investigated within a macroscopic-microscopic model based on the Lublin-Strasbourg-Drop macroscopic energy and shell plus pairing-energy corrections obtained from a Yukawa-folded mean-field potential at the desired deformation. A new, rapidly converging Fourier shape parametrization is used to describe nuclear shapes. The stability of shape isomeric states with respect to non-axial and higher-order deformations is investigated. [ABSTRACT FROM AUTHOR]

In this work we report on recent microscopic calculations of K-isomeric states of two-quasiparticle character in well-deformed rare-earth nuclei and actinide nuclei. In these calculations we employ a Skyrme energy-density functional together with a seniority residual interaction in the Hartree-Fock-BCS approximation with selfconsistent blocking (SCB). The strength of the seniority interaction is calibrated in a consistent way: as some of us showed in Ref. [1] for rare-earth nuclei, the same strength can be obtained in a fit on moments of inertia of eveneven nuclei and in a fit on odd-even mass staggering. The former fitting protocol is used for the actinide nuclei studied here. Once the seniority force was adjusted we calculated properties of variousK-isomeric states without additional parameters. Overall we have obtained a rather good agreement with available data around 154Nd and in the 234U-236Pu region. We also found that an octupole deformation lowers the excitation energy of the Kπ = 6- isomer in 234U. [ABSTRACT FROM AUTHOR]

The potential-energy surfaces of an extended set of heavy and superheavy even-even nuclei with 92≤Z≤126 and isospins 40≤N-Z≤74 are evaluated within the recently developed Fourier shape parametrization. Ground-state and decay properties are studied for 324 different even-even isotopes in a four-dimensional deformation space, defined by nonaxiality, quadrupole, octupole, and hexadecapole degrees of freedom. Nuclear deformation energies are evaluated in the framework of the macroscopic-microscopic approach, with the Lublin-Strasbourg drop model and a Yukawa-folded mean-field potential. The evolution of the ground-state equilibrium shape (and possible isomeric, metastable states) is studied as a function of Z and N. α-decay Q values and half-lives, as well as fission-barrier heights, are deduced. In order to understand the transition from asymmetric to symmetric fission along the Fm isotopic chain, the properties of all identified fission paths are investigated. Good agreement is found with experimental data wherever available. New interesting features about the population of different fission modes for nuclei beyond Fm are predicted. [ABSTRACT FROM AUTHOR]

The moment of inertia for nuclear collective rotations is derived within a semiclassical approach based on the Inglis cranking and Strutinsky shell-correction methods, improved by surface corrections within the nonperturbative periodic-orbit theory. For adiabatic (statistical-equilibrium) rotations it was approximated by the generalized rigid-body moment of inertia accounting for the shell corrections of the particle density. An improved phase-space trace formula allows to express the shell components of the moment of inertia more accurately in terms of the free-energy shell correction. Evaluating their ratio within the extended Thomas-Fermi effective-surface approximation, one finds good agreement with the quantum calculations. [ABSTRACT FROM AUTHOR]

Magnetic properties of deformed odd-mass nuclei are studied within a nonrelativistic mean-field-plus-pairing approach, namely the Skyrme-Hartree-Fock-BCS approach with self-consistent blocking. For an odd number of nucléons these approaches lead to the breaking of the time-reversal invariance. The deviation from the Schmidt values of the isoscalar magnetic dipole moment is known to result from a subtle balance between core-polarization effects and meson-exchange current effects. However, the former are usually calculated in the random phase approximation without time-reversal symmetry breaking at the mean-field level. In this work we show that if one takes into account this symmetry breaking already in the mean-field solution, the correction from core polarization yields a significant contribution to the empirical quenching of the spin gyromagnetic ratios as compared to the free values in deformed odd-mass nuclei. Moreover, we calculate magnetic dipole moments in the Bohr and Mottelson unified-model description with self-consistent blocked mean-field intrinsic states. The obtained results in the A ~ 100 and A ~ 180 mass regions as well as for three actinide nuclei compare favorably with experimental data. [ABSTRACT FROM AUTHOR]

Within the particle-number conserving highly truncated diagonalization approach (amounting to a severely truncated shell model built on self-consistent mean-field single-particle states), we investigate the isospin mixing in the ground state of axially deformed even-even Ν = Ζ nuclei with A < 80. The Skyrme interaction in its SIII parametrization is used to generate the self-consistent mean-field solution, whereas the effective residual interaction is approximated by density-independent S interactions in the Τ = 0 and Τ = 1 isospin channels. In the correlated ground state of the considered nuclei, the obtained values of the isospin-mixing parameter range from a few tens of a percent to a couple of percents. The pairing correlations in both isospin channels are found to increase a little the isospin-mixing parameter with respect to the Hartree-Fock value by two competing mechanisms. In the Τ = 0 channel, isospin mixing is brought mostly by neutron-proton one-pair excitations, whereas in the Τ -- 1 channel it is essentially generated by the difference between neutron-neutron and proton-proton one-pair excitations. [ABSTRACT FROM AUTHOR]

Semiclassical shell-structure components of the collectivemoment of inertia are derived within the mean-field cranking model in the adiabatic approximation in terms of the free-energy shell corrections through those of a rigid body for the statistically equilibriumrotation of a Fermi system at finite temperature by using the nonperturbative extended Gutzwiller periodic-orbit theory. Their analytical structure in terms of the equatorial and 3-dimensional periodic orbits for the axially symmetric harmonic oscillator potential is in perfect agreement with the quantum results for different critical bifurcation deformations and different temperatures. [ABSTRACT FROM AUTHOR]