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The cross sections for the production of the isotopes Au in Au reactions are calculated based on numerical solution of the time-dependent Schrödinger equation for outer neutrons of colliding nuclei. It is shown that the fusion–evaporation contribution to experimental data is small. By and large, the results of the calculations agree with experimental data. [ABSTRACT FROM AUTHOR]

The energy spectra of alpha particles from reactions induced by 280-MeV Ca beams incident to Ta, Au, and U targets were measured at an angle of 0 by means of a high-resolution magnetic analyzer (MAVR setup). The sensitivity of the procedure used made it possible to measure alpha-particle yields that are five to six orders of magnitude less than the maximum yield. The cross section for the formation of alpha particles is shown to be dependent on their binding energy in the target nucleus. The experimental data obtained from these measurements were analyzed on the basis of the model of two- and three-body reaction channels and the model of moving sources. [ABSTRACT FROM AUTHOR]

Calculations of the probability densities and energies of the ground states for α -cluster nuclei 12 C (3 α ), 16 O (4 α ), 20 Ne ( 5 α ), 24 Mg ( 6 α ), 28 Si ( 7 α ) and for nuclear molecules 9 Be ( 2 α + n ), 10 Be ( 2 α + 2 n ), 10 B ( 2 α + n + p ), 10 C ( 2 α + 2 p ), 11 B ( 2 α + 2 n + p ), 11 C ( 2 α + n + 2 p ) were performed by the Feynman Path Integral method using parallel computing based on NVIDIA CUDA technology. In addition, 12 C (3 α ) was considered in three-body hyperspherical harmonics formalism with a new effective method of solving hyperradial equation using cubic spline interpolation. The spatial structures of the ground states of 12 C and 16 O correspond to simple geometric shapes, a regular triangle and a tetrahedron, respectively, with wide α -cluster clouds in their vertices. The 24 Mg nucleus has the shape of a pair of equal regular triangles with wide α -cluster clouds in their vertices as well. The nuclei 9 Be, 10 Be, 10 B, 10 C, 11 B, 11 C have molecular structure with valence neutrons and/or protons between two α -clusters. [ABSTRACT FROM AUTHOR]

The differential cross sections for alpha-particle emission at an angle of 0 in the reactions induced by a 6-MeV/nucleon Fe beams incident to U and Ta targets were measured versus the alpha-particle energy by means of a high-resolution magnetic analyzer (MAVR setup). The resulting spectra were found to contain fast alpha particles of energy corresponding to the two- and three-body exit reaction channels, including alpha particles of energy close to the two-body kinematical limit. The data obtained in this experiment were analyzed on the basis of the moving-source model. The emission of nonequilibrium alpha particles in the forward direction from the heavier target nucleus upon the complete or incomplete fusion of nuclei was revealed within the time-dependent quantum approach. [ABSTRACT FROM AUTHOR]

A numerical solution of the time-dependent Schrödinger equation is applied in studying the dynamics of incomplete fusion of nuclei and cluster- and nucleon-transfer reactions at energies near the Coulomb barrier. The evolution of wave functions for all nucleons is used to describe multineutron- and multiproton-transfer reactions in 40Ca+124Sn collisions. The results of the calculations are in satisfactory agreement with experimental data. The evolution of the alpha-cluster wave function in the 12C nucleus is used to calculate the incomplete-fusion cross section for the 12C+51V reaction. Agreement with experimental data for the (12C, α) and (12C, 2α) channels is attained. [ABSTRACT FROM AUTHOR]

The ground-state energies and the squared moduli of the ground-state wave functions are calculated for the H, He, Li, and Be nuclei by Feynman's continual (path) integrals method. The results are in satisfactory agreement with experimental data. [ABSTRACT FROM AUTHOR]

The fusion cross sections for the O+Al, O+Ni, and He+Au reactions were calculated by the coupled-channel method. The radial dependence of matrices that describe coupling to valence-neutron-rearrangement channels was determined with the aid of two-center wave functions. The coupling-strength parameters were evaluated on the basis of numerically solving the time-dependent Schrödinger equation. Satisfactory agreement with experimental data was obtained. [ABSTRACT FROM AUTHOR]

The time-dependent Schrödinger equation and the method of perturbed stationary states that is based on the expansion of the total wave function for the system of two nuclear cores and a nucleon in a set of nucleon two-center functions are used to describe nucleon transfers and fusion in low-energy nuclear reactions. A set of multichannel equations that couple the relative motion of nuclei to the motion of the nucleon is obtained. The kinetic-energy coupling matrix is similar to the coupling matrix for collective excitations of nuclei. [ABSTRACT FROM AUTHOR]

The problem of quantum description of near-barrier fusion of heavy nuclei taking place under strong coupling of relative motion with external nucleons transfers is studied. The method of perturbed stationary states, founded on decomposing of a full wave function of a system of two nuclei and nucleon by a system of two-center nucleon wave functions, is applied for the description of nucleons transfers at low-energy nuclear reactions. The two-center nucleon energy levels - additions to nucleus-nucleus potential in a channels, and wave functions are calculated by a numerical solution of a Schrödinger equation for an arbitrary axial-symmetrical field with spin-orbit interactions, based on decomposing on Bessel functions and difference scheme along internuclear axis. [ABSTRACT FROM AUTHOR]

new method for numerically solving the Schrö dinger equation for an arbitrary axisymmetric field with allowance for spin-orbit interaction is used to study neutron and proton states in strongly deformed nuclei and dinuclear systems produced at the first step of the fusion of nuclei. A quadrupole-octupole parametrization is proposed for the shape of a dinuclear system and for the potential energy of nucleons in this system. The experimentally observed deformations of the Mg nuclei and the difference in the cross sections for the fusion of nuclei in the O + Ni and O + Ni systems are explained qualitatively. [ABSTRACT FROM AUTHOR]

The problem of constructing a quantum-mechanical description of neutron and collective degrees of freedom of dinuclear systems at the first stage of the near-barrier fusion of heavy ions is investigated. A new method for numerically solving the Schrödinger equation for an arbitrary axially symmetric field with allowance for spin-orbit interaction is proposed. Thismethod is not plagued by restrictions on the distance between approaching nuclei or on the elongation of fused nuclei or nuclei undergoing separation. The method is illustrated by applying it to determining neutron two-center (molecular) states in systems of light and heavy nuclei. The experimentally observed properties of the barrier distribution extracted from the energy dependence of the cross section for nuclear fusion are explained on the basis of an analysis of neutron states and excited vibrational and rotational states of a dinuclear system. [ABSTRACT FROM AUTHOR]

The article focuses on the propagation of acoustic waves in the medium consisting of a viscous fluid and an elastic material. A model of acoustic wave propagation in the combined media "fluid-elastic material" was developed. Deducing a strictly averaged system of equations which describe acoustic wave propagation in the medium that is the union of an elastic periodic frame and a viscous incompressible fluid was the goal of the authors.

The problem of a quantum-mechanical description of a near-barrier fusion of heavy nuclei under conditions of a strong coupling of their relative motion to neutron degrees of freedom is studied. New mutually complementing efficient models employing the multidimensional time-dependent Schrödinger equation and methods for numerically solving the problems in question within these models are proposed. This makes it possible to study the evolution of wave functions for outer neutrons and to calculate nucleontransfer probabilities and occupation numbers for quasimolecular states over the entire energy range, including that of deep-subbarrier energies. It is shown that the valence-neutron wave functions extend over the volumes of both colliding nuclei before their surfaces come into contact and even before these nuclei overcome the Coulomb barrier (collectivization of outer nucleons). This gives rise to a substantial neutron-transfer effect on the fusion of nuclei and, in particular, to a sizable increase in the probability of subbarrier fusion for specific combinations of nuclei. [ABSTRACT FROM AUTHOR]

The problem of a quantum-mechanical description of a near-barrier fusion of heavy nuclei that occurs under the conditions of a strong coupling of their relative motion to the rotation of deformed nuclei and to a dynamical deformation of their surfaces is studied. A new efficient method is proposed for numerically solving coupled Schrödinger equations with boundary conditions corresponding to a total absorption of the flux that has overcome a multidimensional Coulomb barrier. The new method involves no limitations on the number of channels that are taken into account and makes it possible to calculate cross sections for the fusion of very heavy nuclei that are used in the synthesis of superheavy elements. A global analysis of the relief of the multidimensional potential surface and of the multichannel wave function in the vicinity of the Coulomb barrier provides a clear interpretation of the dynamics of near-barrier nuclear fusion. A comparison with experimental data and with the results produced by the semiempirical model for taking into account the coupling of channels is performed.© 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

The energy dependence of the total cross sections for the He + Si and Li + Si reactions was measured at beam energies between 5 and 20 MeV per nucleon. The results agree with experimental data published for the He + Si reaction. New data are obtained for the Li + Si reaction in the vicinity of a local enhancement of the total cross section. A theoretical analysis of the possible reasons behind the appearance of this peculiarity in the case of collisions of He and Li nuclei with silicon target nuclei is performed. In particular, the enhancement may owe its origin to the effect of loosely bound projectile nucleons. [ABSTRACT FROM AUTHOR]

Background: Significant enhancement of sub-barrier fusion cross sections owing to neutron transfer with positive Q values was observed in many combinations of colliding nuclei. This degree of freedom has not yet been included into the rigorous quantum coupled-channels (QCC) approach. However, the empirical coupled-channels model with neutron rearrangement [Zagrebaev, Phys. Rev. C 67, 061601 (2003)] has already been successfully used in several papers to reproduce and predict cross sections for sub-barrier fusion reactions of stable nuclei. Purpose: The objective of this study is to combine the QCC approach and the empirical model to account for additional channels of neutron rearrangement. Method: Coupling of relative motion to collective degrees of freedom (rotation of nuclei and/or their surface vibrations) are taken into account within the QCC approach. The probability of transfer of x neutrons with a given Q value is estimated semiclassically. Results: The proposed new model was successfully tested on a few combinations of fusing nuclei 40Ca + 90,94,96Zr, 32S + 90,94,96Zr, and 60,64Ni + l00Mo. The calculated fusion cross sections and barrier distribution functions agree well with experimental data. Conclusions: The model developed in this work confirms all the conclusions previously made within the empirical coupled-channels model with neutron rearrangement [see Rachkov et al., Phys. Rev. C 90, 014614 (2014)]. Moreover, it has an advantage of a more reliable microscopic account for the coupling between relative motion and the collective degrees of freedom. The proposed model can also be used to reproduce the structure of the barrier distribution function. This is a step forward to a complete solution of the long-term problem of accounting for neutron transfer channels in the QCC model. [ABSTRACT FROM AUTHOR]

The energy spectra of alpha particles emitted at an angle of 0 in the interaction of 400-MeV Fe ions with U, Ta, and Be targets were measured by means of a high-resolution magnetic analyzer (MAVR, which is the acronym of the Russian name of this setup). The energy spectra of charged particles ranging from Li to Ne were also measured. The experimental data obtained in this way indicate that the emission of alpha particles is a dominant process in the above reactions. Particles of high energy, up to those in the vicinity of the so-called kinematical limit for two-body reactions, were observed with a rather high yield. The sensitivity of the experimental procedure that employed the aforementioned magnetic analyzer made it possible to observe events characterized by cross-section values smaller by six to eight orders of magnitude than that at the maximum of the spectrum. The cross section for the production of light particles is shown to be dependent on their binding energy in the target. The experimental data obtained in this study were analyzed with aid of the moving-source model. [ABSTRACT FROM AUTHOR]

We propose and have implemented a design of a bridge-type stripline parameteric scatterer. It is a system of four parametric oscillators connected according to the bridge-type scheme. A stripline antenna tuned to the frequency of the pumping signal is connected to one arm of the system, and an antenna tuned to the frequency of its half-subharmonic is connected to its second arm. The parametric oscillators are made as parametric electric circuits that consist of a lumped inductance and a nonlinear capacity. The role of the latter is played by a semiconducting diode. The possibility to match antennas with a system of parametric oscillators is justified using the model of the stripline parametric scatterer. The stripline parametric scatterer was tested in numerical and full-scale experiments. The results obtained are in good agreement. [ABSTRACT FROM AUTHOR]

In this paper the results of measurements of the total cross sections for the 11Li+28Si reaction in the beam energy range 7A-25A MeV are presented. The experimental cross sections were obtained by registration of the prompt gamma and neutron radiation accompanying the interaction of 11Li nuclei with 28Si nuclei. The total cross sections for the 11Li+28Si reaction are calculated based on a numerical solution of the time-dependent Schrödinger equation for the external weakly bound neutrons of the projectile nucleus 11Li. The calculated total reaction cross sections are in good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

Using the process model, we describe the phase, amplitude, polarization, and spatial characteristics of the parametric scatterer. The mathematical model of the parametric scatterer, which is developed on the basis of its equivalent circuit, is also discussed. The relation between the parameters of the process and mathematical models of the parametric scatterer is shown. The transient processes during simultaneous action of the pump- and synchronization-signal radio pulses on the parametric scatterer are studied. We show that it is expedient to use the synchronization radio pulse at the reply-signal frequency not only for disambiguation of the initial phase of the reply signal, but also for quick excitation of the parametric circuit. [ABSTRACT FROM AUTHOR]

An Erratum to this paper has been published: https://doi.org/10.1134/S1063778822330018 [ABSTRACT FROM AUTHOR]

This paper contains a survey of some results related to the theory of strongly inhomogeneous media and also new results on the description of finite volume eigen-oscillation spectra whose dynamics is described by effective (averaged) models of such media. [ABSTRACT FROM AUTHOR]