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E. B. Balbutsev

Publications and source records attributed to E. B. Balbutsev.

17 recordsLinked to original sources
arXiv2026

Spin and orbital scissors modes in $^{166}$Er

Recently, low-energy dipole excitations in $^{166}$Er were investigated via nuclear resonance fluorescence [T. Shizuma {\it et al}, Phys. Rev. C {\bf 113}, 044325 (2026)]. The magnetic dipole strength associated with the nuclear scissors mode was extracted for excitation energies between 2.2 and 3.5 MeV. It was found that the $M1$ strength distribution is separated into two groups. We interpret this splitting as caused by the spin degrees of freedom instead of the nucleus nonaxiality suggested by authors.

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arXiv2026

Giant Dipole Resonance and Related Spin-dependent Excitations

The time-dependent Hartree-Fock equation is solved by the Wigner Function Moments method taking into account spin degrees of freedom. Energies and reduced transition probabilities of $K^π=0^-$, $1^-$ and $2^-$ excitations are calculated taking $^{164}$Dy as an example. The spin degrees of freedom give rise to the electric Spin Dipole Resonance. Its properties and interplay with the Giant Dipole Resonance are investigated. The deformation-induced splitting of the spin $M2$ resonance is discussed. The results of calculations are compared with the experimental data and other theoretical studies.

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arXiv2023

Scissors mode in transuranium elements

The scissors mode is investigated in the actinides region, including even-even superheavy nuclei up to $^{256}$No, within the Time Dependent Hartree-Fock-Bogoliubov (TDHFB) approach. The solution of TDHFB equations by the Wigner Function Moments (WFM) method predicts a splitting of the scissors mode into three intermingled branches due to spin degrees of freedom. Both the calculated energy centroid and integrated $M1$ strength in $^{254}$No are in good agreement with the results of recent measurements performed by the Oslo method. The energy centroids and summed $B(M1)$ values for others transuranium nuclides are predicted. The calculations are performed also for $^{232}$Th and $^{236,238}$U isotopes using an updated compilation of deformation parameters. The results are compared with that obtained previously by WFM theory and with the latest experimental data. Progress has been achieved in theoretical understanding of the origins of double-humped structure of scissors spectrum observed in the Actinides.

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arXiv2023

Electric $1^+$ state below nuclear scissors

The solution of time dependent Hartree-Fock-Bogoliubov equations by the Wigner function moments method predicts four low-lying $1^+$ states. Three of them are known as various scissors modes. Fourth state is disposed below all scissors modes and has the electrical nature. It is found that it represents one of three branches of $2^+$ state which can exist in spherical nuclei and which is split in deformed nuclei. It is discovered, that the antiferromagnetic properties of nuclei lead to the splitting of $2^+$ states already at the zero deformation.

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arXiv2019

Triplet structure of nuclear scissors mode

The fine structure of the scissors mode is investigated within the Time Dependent Hartree-Fock-Bogoliubov (TDHFB) approach. The solution of TDHFB equations by the Wigner Function Moments (WFM) method predicts a splitting of the scissors mode into three intermingled branches. Together with the conventional scissors mode two new modes arise due to spin degrees of freedom. They generate significant $M1$ strength below the conventional energy range. The results of calculations of scissors resonances in Rare Earths and Actinides by WFM and QPNM methods are compared with experimental data. A remarkable coherence of both methods together with experimental data is observed.

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arXiv2018

Experimental status of the nuclear spin scissors mode

With the Wigner Function Moments (WFM) method the scissors mode of the actinides and rare earth nuclei are investigated. The unexplained experimental fact that in $^{232}$Th a double hump structure is found finds a natural explanation within WFM. It is predicted that the lower peak corresponds to an isovector spin scissors mode whereas the higher lying states corresponds to the conventional isovector orbital scissors mode. The experimental situation is scrutinized in this respect concerning practically all results of $M1$ excitations.

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arXiv2016

Nuclear scissors modes and hidden angular momenta

The coupled dynamics of low lying modes and various giant resonances are studied with the help of the Wigner Function Moments method generalized to take into account spin degrees of freedom and pair correlations simultaneously. The method is based on Time Dependent Hartree-Fock-Bogoliubov equations. The model of the harmonic oscillator including spin-orbit potential plus quadrupole-quadrupole and spin-spin interactions is considered. New low lying spin dependent modes are analyzed. Special attention is paid to the scissors modes. A new source of nuclear magnetism, connected with counter-rotation of spins up and down around the symmetry axis (hidden angular momenta), is discovered. Its inclusion into the theory allows one to improve substantially the agreement with experimental data in the description of energies and transition probabilities of scissors modes.

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arXiv2015

Orbital and spin scissors modes in superfluid nuclei

Nuclear scissors modes are considered in the frame of Wigner function moments method generalized to take into account spin degrees of freedom and pair correlations simultaneously. A new source of nuclear magnetism, connected with counter-rotation of spins up and down around the symmetry axis (hidden angular momenta), is discovered. Its inclusion into the theory allows one to improve substantially the agreement with experimental data in the description of energies and transition probabilities of scissors modes in rare earth nuclei.

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arXiv2013

A new type of nuclear collective motion - the spin scissors mode

The coupled dynamics of low lying modes and various giant resonances are studied with the help of the Wigner Function Moments method on the basis of Time Dependent Hartree-Fock equations in the harmonic oscillator model including spin-orbit potential plus quadrupole-quadrupole and spin-spin residual interactions. New low lying spin dependent modes are analyzed. Special attention is paid to the spin scissors mode.

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arXiv2011

Spin Scissors Mode and the Fine Structure of M1 States in Nuclei

The coupled dynamics of low lying modes, including the scissors mode, and various giant quadrupole resonances are studied with the help of the Wigner Function Moments method generalized to take into account spin degrees of freedom. Equations of motion for collective variables are derived on the basis of Time Dependent Hartree-Fock equations in the model of harmonic oscillator with spin orbital mean field potential plus quadrupole-quadrupole residual interaction. Introducing spin allows one to consider new types of nuclear collective motion where the nucleons with spin 'up' oscillate against nucleons with spin 'down'.

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arXiv2008

Nuclear Scissors with Pairing and Continuity Equation

The coupled dynamics of the isovector and isoscalar giant quadrupole resonances and low lying modes (including scissors) are studied with the help of the Wigner Function Moments (WFM) method generalized to take into account pair correlations. Equations of motion for collective variables are derived on the basis of the Time Dependent Hartree-Fock-Bogoliubov (TDHFB) equations in the harmonic oscillator model with quadrupole-quadrupole (QQ) residual interaction and a Gaussian pairing force. Special care is taken of the continuity equation.

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arXiv2007

Nuclear Scissors Mode with Pairing

The coupled dynamics of the scissors mode and the isovector giant quadrupole resonance are studied using a generalized Wigner function moments method taking into account pair correlations. Equations of motion for angular momentum, quadrupole moment and other relevant collective variables are derived on the basis of the time dependent Hartree-Fock-Bogoliubov equations. Analytical expressions for energy centroids and transitions probabilities are found for the harmonic oscillator model with the quadrupole-quadrupole residual interaction and monopole pairing force. Deformation dependences of energies and $B(M1)$ values are correctly reproduced. The inclusion of pair correlations leads to a drastic improvement in the description of qualitative and quantitative characteristics of the scissors mode.

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arXiv2006

The Nuclear Scissors Mode from Various Aspects

Three methods to describe collective motion, Random Phase Approximation (RPA), Wigner Function Moments (WFM) and the Green's Function (GF) method are compared in detail and their physical content analyzed on an example of a simple model, the harmonic oscillator with quadrupole--quadrupole residual interaction. It is shown that they give identical formulae for eigenfrequencies and transition probabilities of all collective excitations of the model, including the scissors mode, which is the subject of our special attention. The exact relation between the RPA and WFM variables and the respective dynamical equations is established. The transformation of the RPA spectrum into the one of WFM is explained. The very close connection of the WFM method with the GF one is demonstrated. The normalization factor of the ``synthetic'' scissors state and its overlap with physical states are calculated analytically. The orthogonality of the spurious state to all physical states is proved rigorously. A differential equation describing the current lines of RPA modes is established and the current lines of the scissors mode analyzed as a superposition of rotational and irrotational components.

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arXiv2005

The nuclear scissors mode within two approaches (Wigner function moments versus RPA)

Two complementary methods to describe the collective motion, RPA and Wigner function moments method, are compared on an example of a simple model - harmonic oscillator with quadrupole-quadrupole residual interaction. It is shown that they give identical formulae for eigenfrequencies and transition probabilities of all collective excitations of the model including the scissors mode, which here is the subject of our special attention. The exact relation between the variables of the two methods and the respective dynamical equations is established. The normalization factor of the "synthetic" scissors state and its overlap with physical states are calculated analytically. The orthogonality of the spurious state to all physical states is proved rigorously.

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arXiv2003

The Nuclear Scissors Mode in a Solvable Model

The coupled dynamics of the scissors mode and the isovector giant quadrupole resonance is studied in a model with separable quadrupole-quadrupole residual interactions. The method of Wigner function moments is applied to derive the dynamical equations for angular momentum and quadrupole moment. Analytical expressions for energies, B(M1)- and B(E2)-values, sum rules and flow-patterns of both modes are found for arbitrary values of the deformation parameter. Some predictions for the case of superdeformation are given. The subtle nature of the phenomenon and its peculiarities are clarified.

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arXiv1994

Role of the Low-Lying Isoscalar Dipole Modes in the Polarization Potential

An analysis of the real and imaginary part of the polarization potential in terms of the relative contributions of the single collective states for the $ ^{208}Pb + ^{208}Pb $ system has been done. The polarization potential has been calculated within the Feshbach formalism taking into account the collective states calculated with the Wigner function moments method. The contribution of the isoscalar giant dipole resonance states has been estimated being of the order of 10 - 20 \% of the total at relatively low incident energy.

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