Vol 81, No 10 (2017)

A way of calculating the electromagnetic field generated by a narrow beam of gamma quanta passing through a gas medium is used to describe the field produced by the interaction between water and gamma radiation with an energy of 1 MeV. Variations in the electromagnetic field energy generated by secondary electrons are obtained as a function of the angle of observation.

Experimental double-differential and integral spectra of (³He, xp), (³He, xd), (³He, xt), (³He, x³He) and (³He, xα) reactions on ¹¹²Sn nuclei induced by 50 MeV 3He ions are presented. Theoretical calculations of the experimental inclusive spectra of the reactions are performed using the exciton model of preequilibrium decay. The corresponding mechanisms of reactions are determined. The experimental results can be used to develop new approaches in the theory of nuclear reactions, and to design safe and wasteless hybrid nuclear power plants.

It has long been believed that small colliding systems (p+Au, d+Au, ³He + Au) are can only be used to study the collective effects of cold nuclear matter. However, recent studies on the RHIC and LHC accelerators indicate there are flowlike collective effects characterized by the high multiplicity of charged particles produced in these collisions. Whether these effects result from the hydrodynamic expansion of a dense and hot thermalized medium or are caused by the initial state remains an open question. This work reports the results from measuring flow characteristics in d + Au and ³He + Au collisions at an energy of 200 GeV in the PHENIX experiment on the RHIC collider. Attempts to describe the results theoretically are discussed.

The expansion of even–even nucleus energy in power series of deviations from the given values of neutron and proton numbers. The calculation of the expansion parameters up to the sixth order shows that the values of parameters are sensible to the choice of the group of nuclei used for the calculation. This indicates that the nuclear energy surface is not sufficiently smooth (or completely differentiable). It is shown that the expression proposed earlier by the authors for the pairing energy of an odd nucleus in a definite quantum state does not need to be refined and can be used for the subsequent analysis of pairing energies.

Results from calculating zero sound excitations in isospin asymmetric nuclear matter are presented. A polarization operator constructed in the random phase approximations is used in the calculations. Three branches of the complex solutions ω_sτ(k), τ = p,n,np are presented. The type of branch depends on that of the considered branch damping. An imaginary part of the solution corresponds to the damping of collective excitations due to mixing with the background of noninteracting (1) proton particle–hole pairs (ω_sp(k)), (2) neutron particle–hole pairs (ω_sn(k)), and (3) both proton and neutron particle–hole pairs (ω_snp(k)). The behavior of the solutions upon variations in density depends on the value of the asymmetry parameter.

Path calculations for fragments of the spontaneous true ternary fission of a ²⁵²Cf nucleus are performed. The results are considered from the standpoint of symmetries underlying the generalized nuclear model, and substantiation of the physical picture of the coaxial emission of the fragments during true ternary fission. The calculations are performed with allowance for the ROT effect, which is regarded as a major disturbance in this scenario. The obtained results are in agreement with experimental data.

The Dirac equation is considered in five-dimensional spaces with signatures (2,3), (4,1) and (0,5). The algebraic spinor formalism with the application of fermionic variables is used as the basis of real Clifford algebras and the module over this algebra. It is shown that solutions to the five-dimensional Dirac equation in spaces with signatures (2,3) and (4,1) can be expanded over solutions with zero value of the fifth component of the generalized momentum, and the equation is equivalent to an equation in four-dimensional spacetime.

We present a novel method, based on the single particle Schroedinger equation, to determine the central potential (mean-field) directly from the single particle matter density and its first and second derivatives. As an example, we consider the experimental data for the charge density difference between the isotones ²⁰⁶Pb–²⁰⁵Tl, deduced by phase shift analysis of elastic electron scattering cross-section measurements and corresponds to the shell model 3s_1/2 proton orbit, and determine the corresponding single particle potential. We also present results of least-square fits to parametrized single particle potentials. The 3s_1/2 wave functions of the determined potentials reproduce fairly well the experimental data within the quoted errors. More accurate experimental data, with uncertainty smaller by a factor of two or more, may answer the question how well can the data be reproduced by a calculated 3s_1/2 wave function.

The absorption of a nanocomposite of silver nanoparticles and arabinogalactan in the UV–Vis spectral range is due to the presence of end aldehyde groups in the arabinogalactan and plasmon vibrations in 0D nanosilver. The absorption spectrum of a fundamentally new nanocomposite of silver with arabinogalactan-g-polypyrrole block copolymer reveals additional long-wavelength overlapping absorption bands resulting from the longitudinal component of plasmon resonance in 1D nanosilver and polarons in polypyrrole.

Regimes of the natural and mixed convection of melts with Prandtl numbers ten and 16 are studied experimentally and numerically. The evolution of spatial shape of flow as the Reynolds number rises is studied, as is that of heat transfer on the crystallization front at fixed values of the Grashof and Marangoni numbers, relative to the crystal radius. The boundaries of transitions to nonstationary flow regimes are determined.

A study of the nature of electronic transitions in different structural forms of pyridoxine hydrochloride molecule shows that the maxima in experimental absorption spectra at wavelengths 244 ± 1 nm, 310 ± 1 nm (pH 12.5), 291 ± 1 nm (pH 1.1, pH 4.1), 258 ± 1 nm, 291 ± 1 nm, and 324 ± 1 nm (pH 4.15) are, along with the corresponding lines in theoretical spectra, due to electron transitions from occupied molecular p-orbitals localized on the nitrogen atoms in the structure of pyridine rings to the vacant p-orbitals of double C=N bonds.

Results from theoretical simulations of an autolocalized hole (V_k center) and an autolocalized exciton in CaF₂ crystal by meand of ab initio molecular dynamics are presented. All calculations are performed using the density functional theory in the DFT + U approximation. Mechanisms of the diffusion of the V_k center and restructuring between different configurations of an autolocalized exciton in the free crystal and in the presence of the axial stress are identified by simulating the molecular dynamics in the 50 to 450 K range of temperatures.