| 1. |
- Severyukhin, A. P., et al.
(author)
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On Statistical Properties of the Gamow–Teller Strength Distribution in 60 Ca
- 2020
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In: Physics of Atomic Nuclei. - 1063-7788. ; 83:2, s. 171-178
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Journal article (peer-reviewed)abstract
- Abstract: The β-decay half-life and the delayed neutron emission of 60Ca are studied within a microscopic model, which is based on the Skyrme interaction T45 to construct single-particle and phonon spaces. We observe a redistribution of the Gamow–Teller strength due to the phonon-phonon coupling and the tensor correlations, considered in the model. For 60Sc, the spin-parity of the ground state is found to be 1+. We predict that the half-life of 60Ca is 0.3 ms, while the total probabilities of the βxn emission is 6.1%. To elucidate the obtained results, the random matrix theory has been applied to analyse the statistical properties of the $$1^{+}$$ spectrum populated in the β-decay. We found a remarkable agreement between the GT strength distribution, obtained within the microscopic approach, and the ones, generated by means of the random coupling between the one- and two-phonon configurations.
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| 2. |
- Severyukhin, A. P., et al.
(author)
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Random matrix analysis of the monopole strength distribution in 208Pb
- 2016
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In: Physics of Atomic Nuclei. - 1063-7788. ; 79:6, s. 835-841
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Journal article (peer-reviewed)abstract
- We study statistical properties of the 0+ spectrum of 208Pb in the energy region Ex ≤ 20 MeV. We use the Skyrme interaction SLy4 as our model Hamiltonian to create a single-particle spectrum and to analyze excited states. The finite-rank separable approximation for the particle–hole interaction enables us to perform the calculations in large configuration spaces. We show that while the position of the monopole resonance centroid is determined by one-phonon excitations of 0+, the phonon–phonon coupling is crucial for the description of the strength distribution of the 0+ spectrum. In fact, this coupling has an impact on the spectral rigidity Δ3(L) which is shifted towards the random matrix limit of the Gaussian orthogonal ensembles.
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| 3. |
- Severyukhin, A. P., et al.
(author)
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Two-phonon structures for beta-decay theory
- 2018
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In: International Conference on Nuclear Structure and Related Topics (NSRT18). - : EDP Sciences. - 2101-6275. ; 194
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Conference paper (peer-reviewed)abstract
- The β-decay rates of 60Ca have been studied within a microscopic model, which is based on the Skyrme interaction T45 to construct single-particle and phonon spaces. We observe a redistribution of the Gamow-Teller strength due to the phonon-phonon coupling, considered in the model. For 60Sc, the spin-parity of the ground state is found to be 1+. We predict that the half-life of 60Ca is 0.3 ms, while the total probability of the βxn emission is 6:1%. Additionally, the random matrix theory has been applied to analyze the statistical properties of the 1+ spectrum populated in the β-decay to elucidate the obtained results.
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| 4. |
- Severyukhin, A. P., et al.
(author)
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Damped transient response of the giant dipole resonance in the lead region
- 2018
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In: Physical Review C. - 2469-9985. ; 98:4
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Journal article (peer-reviewed)abstract
- We analyze thoroughly the statistical properties of the 1- spectrum in energy interval 9.5-18.5 MeV for Hg206, Pb204,206,208, and Po210 nuclei. To this aim we use the Skyrme interaction SLy4 and the volume pairing interaction, treated in the BCS approximation, as our model Hamiltonian to create a single-particle spectrum and to analyze excited states. The excited states are obtained in the quasiparticle random phase approximation taking into account the coupling between one- and two-phonon states. The obtained spectra (studied by means of the nearest-neighbour spacing distribution, Δ3-statistics and the Porter-Thomas distribution) indicate on the onset of statistical properties close to those of the Gaussian Orthogonal Ensembles. The comparison of the results, obtained with the aid of the coupling calculated microscopically and by means of the Gaussian random distribution, demonstrates a close similarity in the description of the spreading widths of the Isovector Dipole Giant Resonanse of the considered nuclei. Furthermore, we show that employing the random distribution for the coupling between microscopic one-phonon states and two-phonon states, generated by the Gaussian Orthogonal Ensembles distribution, a good agreement is also obtained with the microscopic description of the decay widths.
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| 5. |
- Severyukhin, A. P., et al.
(author)
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Hybrid model for the damped transient response of giant dipole resonances
- 2021
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In: Physical Review C. - 2469-9985. ; 104:4
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Journal article (peer-reviewed)abstract
- We suggest the hybrid model for the description of the dipole spreading widths, in which the strength function is built on the one-phonon strength distribution folded with the energy-dependent Lorentzian. Its energy dependence is brought about by (i) the energy-dependent smearing parameter and (ii) the energy-dependent shift of the one-phonon states. These variables are estimated by means of the two-phonon density, provided by a modified Fermi gas model with uniformly spaced states, and with the aid of the weak constant interaction between the one-phonon states and the two-phonon states, considered as background states. Based on calculated one-phonon states, the model is analytically solvable. To explore the validity of the model we analyze the properties of the spectrum in , , and nuclei. Our results demonstrate that the description of the decay widths within the latter approach is in good agreement with that obtained in the quasiparticle random phase approximation, by means of the random distribution of the coupling between microscopic one-phonon states and two-phonon states, generated by the Gaussian orthogonal ensemble distribution.
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| 6. |
- Severyukhin, A. P., et al.
(author)
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Reply to "comment on 'Spreading widths of giant resonances in spherical nuclei : Damped transient response' "
- 2018
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In: Physical Review C. - 2469-9985. ; 97:5
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Journal article (peer-reviewed)abstract
- We demonstrate that our approach [Phys. Rev. C 95, 061305(R) (2017)PRCHCD2469-998510.1103/PhysRevC.95.061305] serves as a useful tool to describe the gross structure of the spreading widths of the giant resonances of the doubly magic heavy nuclei. It reduces significantly the computational efforts implementing the ideas of random matrix distribution of the coupling between one-phonon and two-phonon states and generating the energies of the two-phonon states by means of the Gaussian orthogonal ensemble distribution. We show that the Comment misrepresents our paper and fails to provide plausible arguments against the description of the gross structure with the aid of the random matrix theory.
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| 7. |
- Severyukhin, A. P., et al.
(author)
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Spreading widths of giant resonances in spherical nuclei : Damped transient response
- 2017
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In: Physical Review C: covering nuclear physics. - 2469-9985. ; 95:6
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Journal article (peer-reviewed)abstract
- We propose a general approach to describe spreading widths of monopole, dipole, and quadrupole giant resonances in heavy and superheavy spherical nuclei. Our approach is based on the ideas of the random matrix distribution of the coupling between one-phonon and two-phonon states generated in the random-phase approximation. We use the Skyrme interaction SLy4 as our model Hamiltonian to create a single-particle spectrum and to analyze excited states of the doubly magic nuclei Sn132, Pb208, and 126310. Our results demonstrate that the approach enables to us to describe a gross structure of the spreading widths of the giant resonances considered.
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