The scintillation materials are currently relevant, and developing the technology to create them is a priority. It is related to the search for new alternative scintillation materials and the development of detectors based on them in solving a wide range of modern problems of radiation materials science and instrument engineering, such as conducting the latest experiments in high-energy physics, which requires the registration of high doses of ionizing radiation with a short decay time. This work presents some features of the development of fast perovskite scintillators for high-energy physics applications.
By modeling the beam motion in the recirculator of the MAC multifunctional accelerator complex, the machine’s acceptance criteria were evaluated, and an analysis of the permissible alignment errors of the structural elements was conducted. The possibility of correcting the influence of nonlinear magnetic field effects on the structural elements of the recirculator was demonstrated.
In many crystals with sufficient anharmonicity, a special kind of lattice vibrations, namely, discrete breathers (DBs) can be excited either thermally or by external triggering, in which the amplitude of atomic oscillations greatly exceeds that of harmonic oscillations (phonons). Coherency and persistence of large atomic oscillations in DBs may have drastic effect on quantum tunneling due to correlation effects discovered by Schrodinger and Robertson in 1930. These effects have been applied recently to the tunneling problem by Vysotskii et al., who demonstrated a giant increase of sub-barrier transparency during the increase of correlation coefficient at special high-frequency periodic action on quantum system. In the present paper, it is argued that DBs present the most natural and efficient way to produce correlation effects due to time-periodic modulation of the potential well width (or the Coulomb barrier width) and hence to act as breather 'nano-colliders' (BNC) triggering low energy nuclear reactions (LENR) in solids. Tunneling probability for deuterium (D-D) fusion in 'gap DBs' formed in metal deuterides is shown to increase with increasing number of oscillations by similar to 190 orders of magnitude resulting in the observed LENR rate at extremely low concentrations of DBs.
The results of modelling the characteristics (energy spectra, integral values and transverse distributions in the plane of potential sample placement perpendicular to the electron beam axis) of particle fluxes (e, gamma, n) formed by doublecalculations using the GEANT4 toolkit, the technical characteristics of the M-30 microtron were taken into account. The simulation results make it possible to optimise the process of studying the radiation resistance of structural nuclear materials to particle fluxes (e, gamma, n) on the M-30 microtron. This approach can be used to predict the characteristics of particle fluxes (e, gamma, n) on different types of electron accelerators and to optimise irradiation schemes for experimental samples.
Previous studies by the authors demonstrated the possibility of model-based estimation of signals from scintillation detectors with a ZnSe(Al) scintillator thickness of 3.5 mm, based on the energy absorbed in the scintillator via the photoelectric effect. In the present work, it is confirmed that detector signals for ZnSe(Al) scintillators of different thicknesses (0.5, 1.5, 3.5 mm) are also determined by the fraction of X-ray energy absorbed in ZnSe(Al) due to the photoelectric effect. It is established that the X-ray energy absorbed in the scintillator via the photoelectric effect and producing the same detector signal level depends linearly on the ZnSe(Al) thickness. The study was carried out in the X-ray energy range of 20...150 keV (tube voltage 50...150 kV) using 4 mm aluminum filtration
We obtained the differential scattering cross section for a relativistic charged particle moving parallel and close to a crystalline plane. The rainbow scattering effect is demonstrated within the continuous potential approximation. The problem is treated using the eikonal approximation of quantum electrodynamics.
The driver of the NSC KIPT Subcritical Assembly "Neutron Source" facility is 100 MeV/100 kW electron linear accelerator (Linac). One of the tasks of optimization of the accelerator operation is minimization of the beam energy spread. To provide such task the effective and accurate electron beam energy and its energy spread should be realized. During the commissioning and the first tests of the Linac, it was found that the beam energy spread measurement system should be modified and optimized. In the paper the features of medicated electron beam energy spread measurement system are represented. As a result of modification, the system shown the good efficiency during the accelerator adjustment and NSC KIPT Subcritical Assembly "Neutron Source" facility physical start-up. The measured 100 MeV electron beam energy spread at the center of the SCA transportation channel point is about 1.2 or +/- 0.6% with the measurement accuracy is no worse than 10%.
In the future use of supercritical water for cooling nuclear reactors, it is important to choose structural materials that are not subject to corrosion or corrode minimally. Without any competition, these are ceramic materials. Ceramics based on zirconium dioxide has unique properties that can be used together with the properties of metals. Protective ceramic films multiply the corrosion resistance of metals. Methods of applying films are diverse, from the use of plasma and volatile zirconium compounds to simply immersing the metal in a solution of zirconium salt.
The properties of even-even isotopes Rn with A = 218-226 and Pu with A = 222-230 were calculated in the Hartree-Fock-Bogolyubov approximation taking into account the axial symmetry of nuclei with Skyrme forces SkM* in order to investigate the influence of nucleon pairing forces on the manifestations of octupole deformation in nuclei. For the same purpose, the properties of neutron-rich even-even isotopes Rn with A = 278-286 and Pu with A = 284-292 were additionally investigated. The pairing of nucleons in nuclei is described by zero-range pairing forces of a mixed type. The calculations were carried out with constrained conditions on the deformation parameters of nuclei beta 2 and beta 3. For the considered Rn and Pu isotopes, the octupole deformation of nuclei strongly depends on the choice of the parameters of the nucleon pairing force.
An experimental setup of a universal calorimeter has been developed and manufactured to study heat production during the interaction of composite materials with hydrogen isotopes in the temperature range from room temperature to 650 degrees C. The study can be conducted both at a monotonic increase in temperature at a given rate and at any given temperature in the range from room temperature to 650 degrees C. The setup allows these studies to be conducted under irradiation by quanta with energy from 0.5 to 2.5 MeV at the accelerator complex ELIAS. The results obtained on this universal calorimeter will be used in hydrogen energy.
The paper presents computer simulations of ionization of atomic K-shells and characteristic X-ray radiation (CXR) by high-energy electrons in oriented silicon crystals. It is shown that the variation of the K-shell ionization rate along the particle trajectory directly reflects the features of particle motion in the crystal. For the axial crystal orientation this rate is demonstrated to be significantly influenced by both dechanneling and rechanneling processes. A new method for measuring the electron dechanneling length, based on the detection of CXR from the lateral surface of a crystal, is proposed. The feasibility of this method is investigated.
The dynamics of the ion beam in the accelerating structure, which is aApart of the immersion probe-forming system, and the condenser in the form of a single electrostatic lens with a decelerating central electrode are simulated. The matrizant method is used for such simulation, which employs an approximate solution of the equations of ion motion in electrostatic structures with axial symmetry. Take to account that deviations from the axis of ion trajectories can be significant, it is necessary to carry out a comparative analysis of the finite difference method, which uses exact equations of motion, as a reference method, and the matrizant method under beam dynamics simulation.
The paper presents the parameters of the hydraulic circulation system of the coolant in the subcritical assembly tank of the Subcritical Nuclear Facility “Neutron Source”. After a prolonged shutdown, tests were performed that confirmed the reliable safe operation of the primary core cooling system of the facility. The obtained numerical characteristics should be verified before the start of pilot operation.
The secondary electron emission induced by relativistic electrons with energies of 10...25 MeV passing through thin amorphous targets (Be, Al, Ni, Cu, Nb, Au) was investigated. A comparative analysis was performed between the experimentally measured emission coefficients and the calculated restricted ionization energy losses (dE/dx). The theoretical model accounts for the exchange effect and the density effect correction, which is shown to be a decisive factor in the emission from the exit surface of the foils. It was established that the ratio of theoretical calculations to experimental data remains close to unity (0.9-1.2) across a wide range of atomic numbers Z = 4-79. This correlation confirms the dominant role of volume ionization and the proportionality of the secondary electron yield to the restricted energy losses in the near-surface layers. The results provide a unified description of the "energy cost" for the production of low-energy electrons and refine the mechanisms of secondary emission for highenergy electron beams.
The energy characteristics of a relativistic charged particle in the field of a plane electromagnetic wave of a given amplitude are studied. The dependence of the particle's energy on its phase coordinate is obtained. The maximum value of the particle's energy during acceleration, as well as the acceleration length and time, are determined. The transverse displacement of the particle over the maximum acceleration length is determined.
Accumulated experimental results on water treatment using nanosecond discharges in air bubbles confirm the practical effectiveness of this approach, while numerical modelling of a negative streamer in the "air bubble-water" system reveals the physics of its formation. Computer simulation has demonstrated the distributions of electric potential and electric field strength, the evolution of space charge, the accumulation of surface charge at the phase interface (similar to 0.017 C/m(2)), the characteristics of current flow in the reactor (electron, displacement, and ion currents), and has provided a detailed analysis of the role of the multiphase medium in the formation of such streamers. Water treatment technology based on nanosecond discharges in air bubbles represents a promising foundation for industrial installations and opens broad opportunities for further theoretical and experimental research.
For the reactions C-12(gamma,np)B-10, N-14(gamma,np)C-12 and O-16(gamma,np)N-14, the total cross-section has been determined as a function of the gamma-quantum energy. The distributions are similar in appearance: as the photon energy increases, the reaction yields rise from the threshold, reaching a maximum in the region of 30...50 MeV; thereafter, the reaction yields decrease smoothly. Taking the reaction threshold (T-0 = E-gamma-Q) into account has allowed us to determine that the positions and widths of the maxima coincide qualitatively. Assuming that the momentum distribution of a multicharged particle (B-10, C-12 and N-14) reflects various mechanisms of the quasi-deuteron model of photon absorption by the nucleus, the events of all reactions were divided into two parts according to the momentum of the multicharged particles. The corresponding partial cross-sections were determined, and it was found that at T-0 < 10 MeV, there occurs the predomination of the model in which nucleons do not interact with the spectator (multi-charged particle) after the quasi-deuteron splits, while for T-0 > 10 MeV, the contribution from the other model, where interaction between a nucleon and the spectator is possible in the final state, rises rapidly, and the contributions from the different interaction models become equal.
To study the shape of deformed nucleus, Landau-type theory of phase transitions with a spatially inhomogeneous order parameter is used. The order parameter is an angular function that describes the deviation of the shape of the nucleus from sphericity. The equilibrium order parameter minimizes the Landau-type energy functional containing various powers of order parameter and its derivatives. Information about collective forces the competition and compromise of which lead to the appearance of various stable deformations of nuclei is extracted from the experimental data. Analysis reveals crucial role of higher derivatives of order parameter and its higher harmonics of modulation.
3D-printing of scintillators is a new approach in detector manufacturing. It has found specific applications in the tracking area, including voxel-type and opacity-controlled light propagation. The latter method involves using composite filaments with predetermined opacity. The use of grains of organic scintillators for this purpose is highly beneficial, as they exhibit pulse-shape discrimination features related to triplet exciton reflection. However, this has not been studied before, primarily due to the low melting temperature of organic scintillators. In this work, we created a series of plastic scintillator samples with varying p-terphenyl grain content and demonstrated their transparency and
Actinium-225 is one of the most promising radionuclides for alpha-therapy of oncological diseases. In this work, the main world technologies for obtaining the isotope 225Ac are analyzed, and a new approach to its production based on supercritical fluid extraction with carbon dioxide (SFE-CO2) is proposed and theoretically substantiated. Based on the results of the conducted research in the field of extraction of heavy metal isotopes by the SFE-CO2 method, it is assumed that this method is capable of providing high selectivity of 225Ac, a reduction in the amount of liquid radioactive waste and automation of the technological cycle. The model proposed for the extraction of 225Ac complexes is presented, the process parameters are discussed and the flowsheet is proposed.
