arXiv subjects

Yu. S. Lutostansky

Publications and source records attributed to Yu. S. Lutostansky.

11 recordsLinked to original sources

arXiv2026

Interaction of accelerator neutrinos with energies up to 55 MeV with ${}^{127}$I nuclei

The interaction of neutrinos with an energy of up to 55~MeV from the Spallation Neutron Source (SNS) accelerator with a perspective ${}^{127}$I detector at the Oak Ridge National Laboratory (United States) has been studied. The resonance structure of the charge-exchange strength function $S(E)$ has been calculated taking into account high-lying resonances, and the effect of this structure on the cross section $σ(E)$ for the accelerator neutrino capture by the ${}^{127}$I nucleus has been examined. The influence of the Gamow-Teller resonance GTR-1 and the second new higher resonance GTR-2 on the energy dependence of the cross section $σ(E)$ has been analyzed. The effect of the high-lying analog resonance AR-2 has also been taken into account for the first time. It has been found that the contributions of GTR-1 to the calculated cross section $σ(E)$ are from 60% to $\approx$80%, and GTR-2 about 12%, and AR-2 $\le$ 10%, respectively. The contribution of high-lying resonances to the $(ν, n)$ and $(ν, 2n)$ neutrino capture cross sections with neutron emission and the formation of the ${}^{126}$I and ${}^{125}$I isotopes, respectively, has been analyzed. The comparison of the cross sections for the interaction of accelerator neutrinos calculated by different methods with experimental data has shown coincidence at energies below the neutron separation threshold $E_x < S_{1n}$ and strong discrepancy at higher energies, which is difficult to explain. A new measurement of cross sections at energies $E_x > S_{1n}$ is needed.

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arXiv2024

Solar neutrino capture by 128, 130Te isotopes and Baksan Large Neutrino Telescope Project

This paper discusses the charge-exchange strength functions $S(E)$ of the isotopes $^{128,130}$Te. The experimental data of the $S(E)$ strength functions obtained from $(^{3}\mathrm{He}, t)$ reactions, as well as the $S(E)$ strength functions calculated in the microscopic theory of finite fermi-systems, are analyzed. The resonance structure of the strength function $S(E)$ is examined, and the Gamow-Teller and Pygmy resonances are identified. The resonance structure of the strength function $S(E)$ is vital for the calculation and analysis of the process of neutrino capture by atomic nuclei.

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arXiv2023

Interaction of solar neutrinos with $^{98,100}$Mo isotopes and the influence of nuclear resonances

The process of neutrino interaction with $^{98}$Mo and $^{100}$Mo isotopes is studied taking into consideration the effect of charge-exchange resonances. The experimental data on the strength functions $S(E)$ obtained in charge-exchange reactions $(p; n)$ and $(^3\mathrm{He}, t)$ and the strength functions $S(E)$ calculated within the theory of finite Fermi systems were used. We studied the effect of the resonance structure of $S(E)$ on the cross sections for solar-neutrino. We investigated the contribution of each high-lying resonance to the capture cross section $σ(E_ν)$. The contributions of all components of the solar neutrino spectrum are calculated. We estimate the contribution of different components of solar neutrinos as the background for the double-beta decay experiments on $^{100}$Mo.

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arXiv2021

Cross sections of solar neutrino capture by 127I nuclei and Gamow Teller resonances

Solar neutrino capture cross-section by 127I nucleus has been studied with taking into account the influence of the resonance structure of the nuclear strength function S(E). Three types of isobaric resonances: giant Gamow-Teller, analog resonance and low-lying Gamow-Teller pigmy resonances has been investigated on the framework of self-consistent theory of finite Fermi systems. The calculations have been performed considering the resonance structure of the charge-exchange strength function S(E). We analyze the effect of each resonance on the energy dependence of the cross-section. It has been shown that all high-lying resonances should be considered. Neutron emission process for high energy nuclear excitation leads to formation 126Xe isotope. We evaluate contribution from various sources of solar neutrinos to the 126Xe/127Xe isotopes ratio formed by energetic neutrinos. 126Xe/127Xe isotope ratio could be an indicator of high-energy boron neutrinos in the solar spectrum. We also discuss the uncertainties in the often used Fermi-functions calculations.

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arXiv2017

Alpha-decay energies of superheavy nuclei for the Fayans functional

Alpha-decay energies for several chains of super-heavy nuclei are calculated within the self-consistent mean-field approach by using the Fayans functional FaNDF$^0$. They are compared to the experimental data and predictions of two Skyrme functionals, SLy4 and SkM*, and of the macro-micro method as well. The corresponding lifetimes are calculated with the use of the semi-phenomenological formulas by Parkhomenko and Sobiczewski and by Royer and Zhang.

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arXiv2017

Nucleosynthesis of transuranium nuclides under conditions of Mike, Par and Barbell thermonuclear explosions

The creation of transuranium nuclides under pulsed neutron fluxes of thermonuclear explosions is investigated within the kinetic model of the astrophysical r process, taking into account the time dependence of the external parameters and the processes accompanying the beta decay of neutron-rich nuclei. Time-dependent neutron fluxes in the interval ~ 10e-6 s were modeled within the framework of the developed adiabatic binary model. The probabilities of beta-delayed processes were calculated on the base of the microscopic theory of finite Fermi systems. Calculations of transuranium nuclides yields Y(A) are made for three experimental USA thermonuclear explosions "Mike" (YM), "Par" (YP) and "Barbel" (YB). The root-mean-square deviations of the calculations compare to the experimental data (r.m.s.) are 91% for YM, 33% for YP, 29% for YB , which are significantly lower than for other known calculations. The exponential approximation of the experimental dependences Y(A) is carried out and the obtained values of r.m.s are equal to 56%, 86.8% and 60.2% for YM, YP and YB correspondingly, which is better or comparable with other calculations. An even-odd anomaly in the observed yields of heavy nuclei is explained by the predominant influence of processes accompanying the beta decay of heavy neutron-excess isotopes.

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arXiv2016

Fayans functional for deformed nuclei. Uranium region

Fayans energy density functional (EDF) FaNDF^0 has been applied to the nuclei around uranium region. Ground state characteristics of the Th, U and Pu isotopic chains, up to the two-neutron drip line, are found and compared with predictions from several Skyrme EDFs. The two-neutron drip line is found for FaNDF^0, SLy4 and SkM^* EDFs for a set of elements with even proton number, from Pb up to Fm.

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arXiv2015

Heavy and superheavy elements production in high intensive fluxes of explosive process

Mathematical model of heavy and superheavy nuclei production in intensive pulsed neutron fluxes of explosive process is developed. The pulse character of the process allows dividing it in time into two stages: very short rapid process of multiple neutron captures with higher temperature and very intensive neutron fluxes, and relatively slower process with lower temperature and neutron fluxes. The model was also extended for calculation of the transuranium yields in nuclear explosions takes into account the adiabatic character of the process, the probabilities of delayed fission, and the emission of delayed neutrons. Also the binary starting target isotopes compositions were included. Calculations of heavy transuranium and transfermium nuclei production were made for Mike, Par and Barbel experiments, performed in USA. It is shown that the production of transfermium neutron-rich nuclei and superheavy elements with A ~ 295 is only possible in case of binary mixture of starting isotopes with the significant addition of heavy components, such as long-lived isotopes of curium, or californium.

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arXiv2015

Charge-exchange resonances and restoration of the Wigner SU(4)-symmetry in heavy and superheavy nuclei

Energies of the giant Gamow-Teller and analog resonances - $E_{\rm G}$ and $E_{\rm A}$, are presented, calculated using the microscopic theory of finite Fermi system. The calculated differences $ΔE_{\rm G-A}=E_{\rm G}-E_{\rm A}$ go to zero in heavier nuclei indicating the restoration of Wigner SU(4)-symmetry. The calculated $ΔE_{\rm G-A}$ values are in good agreement with the experimental data. The average deviation is 0.30 MeV for the 33 considered nuclei for which experimental data is available. The $ΔE_{\rm G-A}$ values were calculated for heavy and superheavy nuclei up to the mass number $A $= 290. Using the experimental data for the analog resonances energies, the isotopic dependence of the difference of the Coulomb energies of neighboring nuclei isobars analyzed within the SU(4)-approach for more than 400 nuclei in the mass number range of $A$ = 3 - 244. The Wigner SU(4)-symmetry restoration for heavy and superheavy nuclei is confirmed. It is shown that the restoration of SU(4)-symmetry does not contradict the possibility of the existence of the "island of stability" in the region of superheavy nuclei.

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arXiv2015

First applications of Fayans functional to deformed nuclei

First calculations for deformed nuclei with the Fayans functional are carried out for the uranium and lead isotopic chains. The ground state deformations and deformation energies are compared to Skyrme-Hartree-Fock-Bogolyubov results of HFB-17 and HFB-27 functionals. For the uranium isotopic chain, the Fayans functional predictions are rather similar properties compared to HFB-17 and HFB-27. However, there is a disagreement for the lead isotopic chain. Both of the Skyrme HFB functionals predict rather strong deformations for the light Pb isotopes which does not agree with the experimental data on charge radii and magnetic moments of the odd Pb isotopes. On the other hand, the Fayans functional predicts a spherical ground state for all of the lead isotopes, in accordance with the data and the known in literature results obtained with the Gogny D1S force and SLy6 functional as well. The deformation energy curves are calculated and compared to four Skyrme functionals, SLy4, Sly6, SkM* and UNEDF1, for $^{238}$U nucleus and several lead deficient Pb isotopes. In the first case, the Fayans functional result is rather close to SkM* and UNEDF1 which, in particularly the latter one, describe the first and second barriers in $^{238}$U rather well. For the light lead isotopes, the Fayans deformation energy curves are qualitatively close to those of the SLy6 functional.

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arXiv1999

On the nucleon instability of heavy oxygen isotopes

The instability of the $^{26}$O nucleus with respect to decay through the two-neutron channel is investigated. It is shown that this isotope, unobserved in the fragmentation experiments, can exist as a narrow resonance in the system $^{24}$O+2n. A role of deformation in formation of the neutron-drip line in the region $N\sim 20$ is discussed.

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