arXiv subjects

V. S. Vasilevsky

Publications and source records attributed to V. S. Vasilevsky.

28 records · Page 2Linked to original sources

arXiv2018

Systematic investigation of the Hoyle-analog states in light nuclei

We investigate resonance states in three-cluster continuum of some light nuclei $^{9}$Be, $^{9}$B, $^{10}$B, $^{11}$B and $^{11}$C. These nuclei are considered to have a three-cluster configuration consisting of two alpha-particles and neutron, proton, deuteron, triton and nucleus $^{3}$He. In this study, we make use two different microscopic three-cluster models. The first model employs the Hyperspherical Harmonics basis to numerate channels and describe three-cluster continuum. The second model is the well-known complex scaling method. The nucleon-nucleon interaction is modeled by the semi-realistic Minnesota and Hasegawa-Nagata potentials. Our main aim is to find the Hoyle-analog states in these nuclei or, in other words, whether it is possible to synthesize these nuclei in a triple collision of clusters. We formulate the criteria for selecting such states and apply them to resonance states, emerged from our calculations. We found that there are resonance states obeying the formulated criteria which make possible syntheses of these nuclei in a stellar environment.

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arXiv2018

Two- and three-cluster decays of light nuclei with the hyperspherical harmonics

We consider a set of three-cluster systems ($^{4}$He, $^{7}$Li, $^{7}$Be, $^{8}$Be, $^{10}$Be) within a microscopic model which involves the hyperspherical harmonics to represent intercluster motion. We selected such three-cluster systems which have at least one binary channel. Our aim is to study whether the hyperspherical harmonics are able and under what conditions to describe two-body channel(s) (nondemocratic motion) or they are suitable for describing three-cluster continuum only (democratic motion). It is demonstrated that a rather restricted number of the hyperspherical harmonics allows us to describe bound states and scattering states in two-body continuum for a three-cluster system.

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arXiv2017

Formation and decay of resonance state in $^{9}$Be and $^{9}$B nuclei. Microscopic three-cluster model investigations

We study nature of the low-lying resonance states in mirror nuclei $^{9}$Be and $^{9}$B. Investigations are performed within a three-cluster model. The model makes use of the hyperspherical harmonics, which provides convenient description of three-cluster continuum. The dominant three-cluster configurations $α+α+n$ and $α+α+p$ in $^{9}$Be and $^{9}$B, respectively, are taken into account. Dominant decay channels for all resonance states in $^{9}$Be and $^{9}$B are explored. Much attention is paid to the controversial $1/2^{+}$ resonance states in both nuclei. We study effects of the Coulomb interaction on energy and width of three-cluster resonances in the mirror nuclei $^{9}$Be and $^{9}$B. We also search for the Hoyle-analogue state which is a key step for alternative way of $^{9}$Be and $^{9}$B syntheses in a triple collision of clusters in a stellar environment.

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arXiv2015

T-matrix in discrete oscillator representation

We investigate T-matrix for bound and continuous-spectrum states in the discrete oscillator representation. The investigation is carried out for a model problem - the particle in the field of a central potential. A system of linear equations is derived to determine the coefficients of the T-matrix expansion in the oscillator functions. We selected four potentials (Gaussian, exponential, Yukawa, and square-well ones) to demonstrate peculiarities of the T-matrix and its dependence on the potential shape. We also study how the T-matrix expansion coefficients depend on the parameters of the oscillator basis such as the oscillator length and the number of basis functions involved in calculations.

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arXiv2015

Dynamics of two-cluster systems in phase space

We present a phase-space representation of quantum state vectors for two-cluster systems. Density distributions in the Fock--Bargmann space are constructed for bound and resonance states of $^{6,7}$Li and $^{7,8}$Be, provided that all these nuclei are treated within a microscopic two-cluster model. The density distribution in the phase space is compared with those in the coordinate and momentum representations. Bound states realize themselves in a compact area of the phase space, as also do narrow resonance states. We establish the quantitative boundaries of this region in the phase space for the nuclei under consideration. Quantum trajectories are demonstrated to approach their classical limit with increasing energy.

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arXiv2015

Spectrum of resonance states in $^6$He. Experimental and theoretical analysis

We explore the structure of resonance states in $^{6}$He by experimental and theoretical methods. We present the results of experimental investigations of the three-body continuous spectrum of $^{6}$He. For this aim, we use the reaction $^{3}$H$( α,pα)nn$, which is induced by the interaction of alpha-particles with a triton at the beam energy $E_α =$~67.2 MeV. The theoretical analysis of the resonance structure in $^{6}$He is carried out within the framework of a three-cluster microscopic model. The model exploits the hyperspherical harmonics to describe the intercluster dynamics. The set of new resonance states is discovered by the experimental and theoretical methods. The energy, width, and dominant decay channels of resonances are determined.The obtained results are compared in detail with the results of different theoretical models and experiments as well.

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arXiv2012

A Microscopic Cluster Description of 12C

We investigate both bound and resonance states in 12C embedded in a three-α-cluster continuum using two distinct three-cluster microscopic models. The first one relies on the Hyperspherical Harmonics basis to enumerate the channels describing the three-cluster continuum. The second model incorporates both Gaussian and Oscillator basis functions, and reduces the three-cluster problem to a two-cluster one, in which a two-cluster subsystem is described by a set of pseudo-bound state states. It is shown that the results agree well with comparable calculations from the literature.

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arXiv2008

A microscopic three-cluster model with nuclear polarization applied to the resonances of 7Be and the reaction 6Li(p,3He)4He

A microscopic model for three-cluster configurations in light nuclei is presented. It uses an expansion in terms of Faddeev components for which the dynamic eqations are derived. The model is designed to investigate binary channel processes in a compound system. Gaussian and oscillator bases are used to expand the wave function and to represent appropriate boundary conditions. We study the effect of cluster polarization on ground and resonance states of 7Be, and on the astrophysical S-factor of the reaction 6Li(p,3He)4He.

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arXiv2000

A netron halo in 8He

The structure of $^8$He is investigated within a three-cluster microscopic model. The three-cluster configuration $α+^2n+^2n$ was used to describe the properties of the ground state of the nucleus. The obtained results evidently indicate the existence of a neutron halo in $^8$He.

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arXiv2000

Algebraic Model for Quantum Scattering. Reformulation, Analysis and Numerical Strategies

The convergence problem for scattering states is studied in detail within the framework of the Algebraic Model, a representation of the Schrodinger equation in an L^2 basis. The dynamical equations of this model are reformulated featuring new "Dynamical Coefficients", which explicitly reveal the potential effects. A general analysis of the Dynamical Coefficients leads to an optimal basis yielding well converging, precise and stable results. A set of strategies for solving the equations for non-optimal bases is formulated based on the asymptotic behaviour of the Dynamical Coefficients. These strategies are shown to provide a dramatically improved convergence of the solutions.

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