Vol 53, No 1 (2018)

The possibility of reconstructing the internal structure of one-dimensional phase objects at diffraction focusing of X-ray spherical wave was investigated. As a crystal analyzer a strongly absorbing wedge-shaped short period superlattice with a rib parallel to the diffraction vector was used in symmetric Laue geometry case. It is shown that by moving a phase object along the direction of diffraction vector one can bring different satellites in the focusing condition. It is possible to restore an additional wave phase acquired in the phase object by recording the entire map of obtained data.

The results of computer simulation of heat propagation processes in the three-layer detection pixel with the superconducting layers of thermoelectric detector after the absorption of single photons energy of 1–1000 eV are presented. We consider the different geometries of the detection pixel consisting of CeB₆ or (La,Ce)B₆ thermoelectric sensor, absorber and heat sink of Nb, Pb or YBCO superconductors. The computations based on the heat conduction equation from the limited volume are carried out by the three-dimensional matrix method for differential equations. It is shown that by changing the materials and dimension of the detection pixel elements, as well as the operating temperature of the detector enables one to obtain the detector to register the photons within the given spectral range, required energy resolution, and counting rate. Such a detector has a number of advantages that allow one to consider the thermoelectric detector as a real alternative to the most promising single photon detectors.

The structure of Au/Li10ZnO/Li1ZnO/LaB₆ consisting of upper Au and lower LaB₆ ohmic electrodes and a p-n junction p-Li10ZnO/n-Li1ZnO, which has the resistive memory where two functions are simultaneously combined, that is, an address access and the process of reading and storing of information is investigated. The resistance ratio (R_reset/R_set = 10), the data storage time (> 3 hours) and the number of switching cycles (> 350) are improved as compared to the corresponding single-layer structures. The resistive memory is explained by the modulation effect of the Li10ZnO layer, the ferroelectric polarization of which, depending on the orientation, changes the width and height of the barrier of the p-n junction formed at the p-Li10ZnO/n-Li1ZnO contact.

The spectral and luminescent investigations of the Pb(MoO₄)_x(WO₄)_1–x crystals doped by the Nd³⁺ ions have been carried out. The investigations have made possible to determine the energies of the Stark levels of the ⁴F_3/2 metastable state, ⁴I_9/2 ground state, ⁴I_11/2 and ⁴I_13/2 excited states, as well as the cross section of transitions associated with the intense lines of emission bands in ⁴F_3/2→⁴I_11/2 and ⁴F_3/2→⁴I_13/2 channels. The emission bands in this crystal are relatively wide, so one would expect the creation of a tunable laser and a broadband amplifier in the 1060 and 1330 nm wavelength regions.

The resonant tunneling transmission of an electron through the quantum wire comprising two three-dimensional δ-potentials located along the nanotube axis is considered. Using the formulas obtained recently for amplitudes of multichannel scattering, the condition (equation) of resonance is found for the multichannel scattering, at which the system under consideration becomes completely transparent for motion of the electron. A procedure based on the method of vector diagrams is proposed for simplification of the resonance equation. It is shown that if the initial energy of longitudinal motion is insufficient for excitation of new scattering channels, then the resonance equation coincides with the corresponding equation of one-dimensional problem.

Relativistic invariant equations are proposed for the action function and the wave function based on the invariance of the representation of the generalized momentum. The equations have solutions for any values of the interaction constant of a particle with a field, for example, in the problem of a hydrogen-like atom, when the atomic number of the nucleus Z > 137. Based on the parametric representation of the action, the expression for the canonical Lagrangian, the equations of motion and the expression for the force acting on the charge during motion in an external electromagnetic field are derived. The Dirac equation with the correct inclusion of the interaction for a particle in an external field is presented. In this form, the solutions of the equations are not limited by the value of the interaction constant. The solutions of the problem of charge motion in a constant electric field, problems for a particle in a potential well, and penetration of a particle through a potential barrier, as well as problem of a hydrogen atom are presented.