Physics of Atomic Nuclei最新文献

The new SPHERE-3 detector is under development. The main purpose of this experiment is to study the mass composition of primary cosmic rays in the energy range of 1–1000 PeV. The difference between this detector and the previous ones in this series is the registration of not only the Cherenkov light reflected from the snow, but also direct light entering the detector. Several options are being considered for recording direct Cherenkov light. The article presents the estimated parameters of the optical scheme of the detector and the first estimations of its sensitivity to the energy and mass of the primary particle. The first approximations of methods used for energy and mass of the primary particle assessment in each event are given, and their accuracy is considered. At the moment, methods for reflected Cherenkov light and direct Cherenkov light processing are being considered independently of each other.

The direct one-nucleon transfer ({}^{40})Ca((alpha), ({}^{3})He)({}^{41})Ca reaction has been investigated at 36 and 40 MeV incident energies. The full finite-range (FFR) distorted-wave Born approximation (DWBA) analysis has been carried out for the angular distributions of the reaction. Two forms of the monotonic potentials namely, Woods–Saxon and Michel, and both the shallow non-monotonic (molecular) and deep non-monotonic (DNM) potentials in the framework of the optical model are used to analyze the transitions to the ground state and to fifteen and twelve excited states in ({}^{41})Ca at 36 and 40 MeV, respectively. The extracted spectroscopic factors from all forms of the optical model potentials have been compared with the previous calculations. To estimate the quality of fits, the (chi_{N}^{2}) values of the optical model potentials are calculated for the (alpha+{}^{40})Ca elastic scattering and the ({}^{40})Ca((alpha), ({}^{3})He)({}^{41})Ca reaction at two incident energies. The present analysis shows that Michel, molecular, and DNM potentials are able to produce a satisfactory fit to the elastic scattering data, but the Woods–Saxon potential is found to be incompetent. Although, all forms of the monotonic and non-monotonic potentials give an overall good description of the angular distributions in most of the states for the reaction analysis at two incident energies. In this study, it has been also observed that the FFR DWBA analysis is apparently satisfactory for the ({}^{40})Ca((alpha), ({}^{3})He)({}^{41})Ca reaction analysis using all forms of the optical model potentials at 36 and 40 MeV.

The evolution of the single-particle characteristics of neutron- and proton-rich isotones with the new magic numbers (N=14), (16) in the (Z) range from 8 to 20 in the dispersive optical model was traced. The calculated energy gaps (N=14) and (16) widened with the increase in excess of protons and neutrons, respectively. At the same time, the deviation of half-sum of the single-particle energies of the last predominantly occupied and the first predominantly unoccupied states from the Fermi energy decreased. The widening of the gaps were enhanced under the assumption of an increase in the diffuseness of the Hartree–Fock component of the dispersive optical model potential with an increase in the neutron excess over the range of (Z) numbers considered. The bubble structure manifests itself clearly in the neutron density distribution of the proton-unstable nucleus ({}^{34})Ca.

A debuncher for a linear accelerator of protons and light ions with a charge-to-mass ratio A/Z from 1 to 3.5 and a beam energy of 7.5 MeV/nucleon is under development at the National Research Nuclear University MEPhI for scientific research and applications. The electrodynamic, thermal, and mechanical processes and the multipactor discharge have been simulated. Problems of design development of the model taking into account technological equipment that can be used for fabrication have been elaborated.

Ti–B–C coatings of various compositions were obtained by magnetron sputtering using a TiB₂–TiC heterophase target and were deposited on a Si(111) substrate. The studies were carried out using glow discharge optical emission spectroscopy, X-ray diffraction, and scanning electron microscopy. The electrical resistivity was measured using the four-probe method. The coatings had a dense, low-defect structure based on the hexagonal TiB₂ phase and were characterized by a uniform distribution of elements throughout the thickness. It has been established that the electrical resistivity decreases from 314 to 249 µΩ cm with an increase in the titanium content in coatings from 27 to 42 at %.

A calibration procedure with ²²Na radioactive sources for the counters of a gamma-nuclear transition spectrometer, which is fully integrated in the infrastructure of the Hyperon+ setup, including trigger and data acquisition systems, is proposed and implemented.

Heat-resistant dielectric composite materials based on organosilicon polymers for the manufacture of parts for low-thrust space engines, for example, the discharge chamber of a high-frequency ion engine, which is one of the types of electric rocket engines, have been synthesized and their properties have been studied. A composition of a polymer-ceramic material based on dimethylsiloxane rubber reinforced with α-phase silicon dioxide powder has been proposed. The composite meets a wide range of requirements for the material of discharge chambers, among which vibration resistance, radio transparency, and heat resistance up to 400°C should be highlighted. A relationship has been established between the heating rate during postvulcanization of a polymer-ceramic composite and its mass loss. It has been shown that the temperature regime during re-vulcanization/annealing of the composite in vacuum significantly affects the operational properties of the discharge chambers. The results of the study have allowed us to successfully produce samples of discharge chambers from this composite for a laboratory model of a high-frequency ion engine with a beam diameter of 100 mm.

The project of a small-sized pulsed neutron generator with a laser deuteron source with magnetic isolation has been proposed with a modification of a pulsed high-voltage Tesla transformer used as the accelerating voltage source. In this case, the electronic conductivity is suppressed by the magnetic field excited in the primary circuit of the transformer. The electrodynamic parameters of the generator diode system have been estimated. The possibility of neutron generation using the Li(p, n)Be nuclear reaction has been shown, which opens up prospects for the effective use of the neutron generator in radiation therapy.

A prototype amplifier with operating frequency f = 2.8 GHz for a pulsed RF power supply of high-power amplifying klystrons is developed. The amplifier’s block diagram is developed. Board topologies are proposed for each amplifier module. Model amplifier modules are assembled and adjusted. The model amplifier is assembled and tested.

The authors investigate patterns of the laser heating of iron oxide nanoparticles depending on their size, shape, and aggregation at the subcellular level. Temperature is measured via time-resolved fluorescence thermometry based on rhodamine B dye. Estimated temperatures are over 100°C, creating favorable conditions for the programmed cell death of tumor cells upon laser hyperthermia.