arXiv subjects

Yu. E. Penionzhkevich

Publications and source records attributed to Yu. E. Penionzhkevich.

6 recordsLinked to original sources

arXiv2025

Probing the cluster structure of $^6$Li with the nuclear reaction $^6$Li + $^{12}$C at 68 MeV

This work presents a combined experimental and theoretical investigation of the nuclear reaction $^{6}$Li + $^{12}$C at a laboratory energy of 68 MeV. The reaction products are identified via the standard $Δ$E-E technique. Angular distributions are constructed for the elastic, inelastic, and deuteron transfer channels by detecting emitted particles -- $^{6}$Li and $α$. Elastic and inelastic scattering of $^{6}$Li on $^{12}$C are analyzed using both the Optical Model and Coupled channels approaches, with the interaction described by a double-folding potential. This potential is calculated based on the three-body wave function of $^{6}$Li. Pronounced coupled-channel effects are observed, which modify the potential and allow accurate reproduction of the experimental cross sections. The resulting polarized potentials provide a more precise description of the initial-state interaction for further reaction modelling. The deuteron transfer channel, $^{12}$C($^{6}$Li, $α$)$^{14}$N, is studied using the Coupled Reaction Channels method. The coupling between the transfer and elastic channels is implemented using the three-body wave function of $^{6}$Li. As an alternative, a regular wave function constructed with a phenomenological Woods-Saxon potential is also employed. Comparison between the calculated differential cross sections and experimental data reveals a more complex and nuanced reaction mechanism, which supports the cluster structure of $^{6}$Li.

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arXiv2024

Search for a neutron dark decay in $^6$He

Neutron dark decays have been suggested as a solution to the discrepancy between bottle and beam experiments, providing a dark matter candidate that can be searched for in halo nuclei. The free neutron in the final state following the decay of $^6$He into $^4$He $+$ $n$ + $χ$ provides an exceptionally clean detection signature when combined with a high efficiency neutron detector. Using a high-intensity $^6$He$^+$ beam at GANIL, a search for a coincident neutron signal resulted in an upper limit on a dark decay branching ratio of Br$_χ\leq 4.0\times10^{-10}$ (95\% C.L.). Using the dark neutron decay model proposed originally by Fornal and Grinstein, we translate this into an upper bound on a dark neutron branching ratio of $\mathcal{O}(10^{-5})$, improving over global constraints by one to several orders of magnitude depending on $m_χ$.

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arXiv2023

Total cross sections for the reactions $^{10,11,12}$Be+$^{28}$Si and $^{14}$B+$^{28}$Si

In this paper, the results of measurements of the total cross sections for the reactions $^{10,11,12}$Be+$^{28}$Si and $^{14}$B+$^{28}$Si in the beam energy range $13A$--$47A$ MeV are presented. The experimental cross sections were obtained by detection of the gamma quanta and neutrons accompanying the interaction of the isotopes of Be and B with $^{28}$Si. It was found that the cross sections for $^{11,12}$Be are similar, but significantly exceed those for $^{10}$Be. A significant increase in the cross sections for $^{12}$Be with decreasing energy is observed in the entire measured energy range. A theoretical explanation of the obtained experimental data is given based on the microscopic model of deformed nuclei and the numerical solution of the time-dependent Schrödinger equation for the outer weakly bound neutrons of the projectile nuclei. The calculated total reaction cross sections are in good agreement with the experimental data.

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arXiv2020

States of $^{12}$N with enhanced radii

The differential cross sections of the $^{12}$C($^3$He,t)$^{12}$N reaction leading to formation of the 1$^+$ (ground state), 2$^+$(0.96 MeV), 2$^{-}$(1.19 MeV), and 1$^{-}$(1.80 MeV) states of $^{12}$N are measured at $E$($^3$He)=40 MeV. The analysis of the data is carried out within the modified diffraction model (MDM) and distorted wave Born approximation (DWBA). Enhanced $rms$ radii were obtained for the ground, 2$^{-}$(1.19 MeV), and 1$^{-}$(1.80 MeV) states. We revealed that $^{12}$B, $^{12}$N, and $^{12}$C in the IAS with T=1, and spin-parities 2$^{-}$ and 1$^{-}$ have increased radii and exhibit properties of neutron and proton halo states.

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arXiv2013

Study of internal structures of 9,10Be and 10B in scattering of 4He from 9Be

A study of inelastic scattering and single-particle transfer reactions was performed by an alpha beam at 63 MeV on a 9$Be target. Angular distributions of the differential cross sections for the 9Be(4He,4He')9Be*, 9Be(4He,3He)10Be and 9Be(4He,t)10B reactions were measured. Experimental angular distributions of the differential cross sections for the ground state and a few low-lying states were analyzed in the framework of the optical model, coupled channels and distorted-wave Born approximation. An analysis of the obtained spectroscopic factors was performed.

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arXiv2006

Microscopic Model Analysis of the $^{6}$He,$^{6}$Li+$^{28}$Si Total Reaction Cross Sections at the Energy Range 5-50 a Mev

The existing and some preliminary experimental data on the total cross sections of the $^{4,6}$He, $^{6,7}$Li +$^{28}$Si reactions at energies E=5-50 A MeV are demonstrated. The data on $^{6}$Li,$^{6}$He+$^{28}$Si are analyzed in the framework of the microscopic optical potential with real and imaginary parts obtained with a help of the double-folding procedure and by using the current models of densities of the projectile nuclei. Besides, the microscopic double-folding Coulomb potential is calculated and its effect on cross sections is compared with that when one applies the traditional Coulomb potential of the uniform charge distribution. The semi-microscopic potentials are constructed from both the renormalized microscopic potentials and their derivatives to take into account collective motion effect and to improve an agreement with experimental data.

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