Atomic Irradiation Research Articles

ЗОРЯНЕ ВИПРОМІНЮВАННЯ У ГАЛАКТИЧНОМУ ЦИКЛІ

The existence of the Universe presupposes the circulation of energy emitted by stars between galaxies and the cosmic environment. The third galactic process presented in the article "Life of Galaxies in the Observable Universe" contains a fragment associated with the release of energy by stellar photons propagating through space. In this report, it is suggested that the release of energy by quanta is carried out through two channels. The first is the transfer of energy to hypothetical particles of the subtle component of dark matter formed from the paired unification of microwave quanta. The second channel is the release of the bulk of the photons' energy to the vacuum structures. The distribution of the returned energy over the two channels is determined by its participation in processes at two different levels. The first level is electromagnetic processes occurring in the plasma of stellar atmospheres. The second is the participation of the returned energy in the processing of stellar waste in galactic centers, when the latter are in the quasar phase and destroy the nuclei of atoms of old stars into the original particles. The participation of vacuum in the reception of energy and its transfer to galaxies means that the vacuum near large masses will be distinguished by an increased density of its energy. The latter should be reflected in the physical constants whose values depend on the state of the vacuum. Such constants include, for example, the electric and magnetic constants. Therefore, one should expect a shift in the spectral lines of radiation of atoms near the nuclei of quasars relative to the spectral lines of radiation emanating from points of the same galaxies, but remote from their centers. The latter means that the indicated difference in redshifts within galaxies can introduce additional errors in determining the distances to them. Classical electrodynamics and the above assumption indicate the dependence of the speed of light on the point of its determination. It is concluded that some physical constants depending on the local density of vacuum energy will be constant only conditionally.

Net emission coefficient of magnesium oxide crystal arc plasma with different Mg particle concentrations

The aim of the present study was to construct a molecular spectral database of magnesium oxide crystal arc plasma, thereby allowing for the net emission coefficient of arc to be calculated at different temperatures, pressures and Mg ratios. First, Rydberg-Klein-Rees inversion method was adopted to reconstruct the potential-energy curves of diatomic molecules. Subsequently, the Schrödinger equation was solved to determine the molecular wave function. This solution combined with the electrical transition moment function facilitates the calculation of radiative transition probabilities between different energy levels and the development of this database. Second, calculation models of the bound-free and free-free radiative absorption cross-section were established and use to calculate the continuous radiation of atoms. Finally, the radiative capability of different particles was calculated separately, followed by calculation of the net emission coefficient of plasma through addition The experimental results reveal that the net emission coefficient of air plasma under atmospheric pressure is consistent with existing research in both its magnitude and trend. Given that Mg can be ionized at lower temperatures, the magnesium oxide crystal arc plasma exhibited a pronounced radiative capacity at these temperatures. Additionally, a larger optical transmission distance corresponded to a reduced net emission coefficient of the plasma.

Nonthermal acceleration radiation of atoms near a black hole in presence of dark energy

We investigate how dark energy affects atom-field interaction. To this end, we consider acceleration radiation of a freely falling atom close to a Schwarzschild black hole (BH) in the presence of dark energy characterized by a positive cosmological constant $\mathrm{\ensuremath{\Lambda}}$. The resulting spacetime is endowed with a BH and a cosmological (or de Sitter) horizon. Our consideration is a nonextremal ($1+1$)-dimensional geometry with horizons far apart, giving rise to a flat Minkowski-like region in between the two horizons. Assuming a scalar (spin-0) field in a Boulware-like vacuum state, and by using a basic quantum optics approach, we numerically achieve excitation probabilities for the atom to detect a photon as it falls toward the BH horizon. It turns out that the nature of the emitted radiation deeply drives its origin from the magnitude of $\mathrm{\ensuremath{\Lambda}}$. In particular, radiation emission is enhanced due to dilation of the BH horizon by dark energy. Also, we report an oscillatory nonthermal spectrum in the presence of $\mathrm{\ensuremath{\Lambda}}$, and these oscillations, in a varying degree, also depend on BH mass and atomic excitation frequency. We conjecture that such a hoedown may be a natural consequence of a constrained motion due to the bifurcate Killing horizon of the given spacetime. The situation is akin to the Parikh-Wilzcek tunneling approach to Hawking radiation where the presence of extra contributions to the Boltzmann factor deforms the thermality of flux. It apparently hints at field satisfying a modified energy-momentum dispersion relation within classical regime of general relativity arising as an effective low energy consequence of an underlying quantum gravity theory. Our findings may signal new ways of conceiving the subtleties surrounding the physics of dark energy.

Impact of the Melt-Refining Process on the Performance of Sodium-Cooled Rotational Fuel-Shuffling Breed-and-Burn Reactors

This study assesses a Rotational Fuel-Shuffling Breed-and-Burn (RFBB) fast reactor that operates in breed-and-burn (B&B) mode with a rotational fuel-shuffling scheme and remains within the 200 displacements per atom (DPA) radiation damage constraint of currently verified cladding materials. The design is based on a commercial-scale fast burner reactor called the Super Power Reactor Innovative Small Module (S-PRISM) reactor. To reduce the high DPA values of discharged fuels, the melt-refining process developed in the Experimental Breeder Reactor-II (EBR-II) project is adopted in this study. The effects of the melt-refining process on the performance of the RFBB are investigated via five scenarios and compared with a core to which the melt-refining process is not applied: Scenario I, “Homogenization,” occurs without the removal of fission products (FPs) during the melt-refining process; Scenario II, “Homogenization and FP Removal,” occurs with the removal of FPs to a fraction similar to that in the melt-refining process developed in the EBR-II project; Scenario III, “Homogenization, FP Removal, and Make-Up,” is similar to Scenario II but makes up fuel losses with natural uranium; Scenario IV, “With 1% TRU [transuranics] Losses,” is similar to Scenario III but is evaluated with 1% of actinides not recovered; Scenario V, “With 10% TRU Losses,” is similar to Scenario III but is evaluated with 10% of actinides not recovered. The results show that it is neutronically and thermal hydraulically feasible to establish a B&B mode with the rotational fuel-shuffling scheme and by reconditioning the fuel whenever its cladding reaches its proven 200 DPA radiation damage limit. In Scenario V, the core is subcritical due to a large number of actinides not being recovered during the melt-refining process. The cores of the other scenarios are all critical. The cores of scenarios in which FPs are removed during the melt-refining process have higher excess reactivity than that of the core of Scenario I (“Homogenization”) and that of the core to which the melt-refining process is not applied. The numerical analyses also show that in scenarios that include making up fuel losses during melt refining, the core is fed with more natural uranium make-up fuel during operation and thus has lower burnup. Other characteristics, such as power density distributions, neutron flux profiles, and fertile and fissile nuclide density distributions, are all stable during operation.

Comprehensive Assessment of Biological Substrates of Professional Sick Person Group by Chemometric and Nuclear Physical Methods

The article deals with the influence of negative factors of working conditions on the health status of NSC KIPT personnel when working with beryllium. Beryllium and its compounds render a general toxic, allergenic and carcinogenic effect on the organism. The high biological activity and toxicity of Be is due to its chemical activity and penetrating ability. The chronic professional disease such as berylliosis occurs as a result of prolonged systematic exposure on the organism of adverse factors. Elemental analysis of biosubstrates provides important information, that in combination with symptoms and other laboratory parameters, can help in the early diagnostics of physiological violations associated with metabolic disorders and exposure of toxic elements. The blood and hair samples were taken from 28 people, among which 5 patients were selected as a control group, and a group of 23 people were former employees of the beryllium production. The content of chemical elements in the biological substrates (blood and hair) of employees was determined by nuclear-physical methods. An elemental analysis was performed on the analytical nuclear physics complex appliance “Sokol”. The methods based on registration of characteristic X-ray radiation of atoms and g-radiation of nuclei excited by accelerated protons is used. After measurements, data arrays were obtained on the content of 14 chemical elements (N, Na, S, Cl, K, Ca, Ti, Mn, Fe, Cu, Zn, Br, Sr, Pb) in blood and hair. The processing of data arrays was carried out using the principal component method which is related to chemometrics technologies. As a result of the work, an analytical program was composed in MATLAB codes which were used to determine the content of elements in biosubstrates that are most sensitive to changes in external conditions. This made it possible to identify certain groups of patients who have different health state indicators, as well as to see the similarities or differences between patients depending on the different concentrations of chemical elements in the blood or hair.

Characterization of the Electroluminescence of Oil Produced by an Electric Discharge

The spectroscopic analysis of low-current electrical discharges (approximately 0.1 mA) in liquid I-40A oil was carried out. The discharge spectrum is similar to that for photoluminescence and hydrodynamic luminescence and is determined mainly by the highlighting individual luminescent centers. There are components in the emission spectrum corresponding to the radiation of atoms of the electrode material, as well as a split Hα hydrogen line. From the analysis of the emission spectrum, the electric field strength was approximately 60 kV/cm and the concentration of electrons ∼1014 cm−3. There were no components corresponding to molecular radiation in the spectrum. It has been hypothesized that the discharge in a liquid occurs when the steam phase forms in the electric field. However, these results raise questions about the composition of this steam phase. Although similar emissions for I-40A oil were produced by electrical discharges and as photo- or hydroluminescence, ultrasonic sonoluminescence has never been observed for I-40A oil. Thus, there is no way to excite the environment with ultrasound, unlike for other forms of luminescence, such as by an electrical discharge.

APPLICATION OF THE METHODS OF THE INTEGER THEORY IN PHYSICS

The article discusses the results of solving two classical problems of physics and their consequences - the problem of radiation of a hydrogen-like atom and the problem of scattering - by the mathematical method of the integer theory. The transition to the formulation of these problems in terms of the integer theory became possible as a result of the formulation of the hypothesis that, during the interaction of physical objects, the exchange of quantities that are conserved occurs in such a way that the conserved quantities have a common measure before and after the interaction (i.e., they are commensurable). The concept of magnitude and unit of measure for bound and free objects is discussed. The introduction of the concept of commensurability made it possible to give physical grounds for “allowed” states in quantum physics and to explain the physics of the previously inexplicable requirement that the Miller numbers-index representing crystallographic planes must be coprime. Physical calculations using the mathematics of integers make it possible to predict a number of important consequences in solving applied problems, in particular, in the physics of the phenomenon of superconductivity. Attention is drawn to the fact that the development of science needs the emergence of new ideas and the conductor of such ideas should be philosophy.

Observation of X-rays during heating a pyroelectric crystal by an infrared laser

A pyroelectric X-ray source is proposed, in which a lithium tantalate crystal is heated by an infrared laser with a wavelength of 10.6 μm. X-ray spectra measured during irradiation of the crystal with infrared radiation and during natural cooling of the crystal include characteristic X-ray radiation of atoms contained in the structural parts of the source, as well as bremsstrahlung of electrons with energies above 50 keV. An 8 mm sodium chloride window was used to inject 64 W infrared radiation into a vacuum chamber with the pyroelectric crystal installed.

Time-Dependent Quantum Dynamics Study of the Interaction between Helium Atom and Synchrotron Radiation

For the first time, excitation and ionization of helium atom (He) induced by synchrotron radiation(SR) is simulated in the present work. It is found that electrons can tunnel through the ground state of helium atom and leave from the atomic region caused by subsequent SR field. Therefore, the ionization of He atom can happen. Additionally, some electrons can be captured by a higher electronic state, which leads to the tunneling excitation from the ground state to a specific excited state.

Collective radiation of multi-atom in cavity under the external driving field

There were several works concerning the collective radiation of two atoms in a cavity. According to their respective criteria, they all claim to have reached superradiation in a cavity (see paragraph 3 of the introduction for details). Dicke [1] defined that superradiation occurs when the radiation power of two atoms is greater than twice that of a single atom. We believe that this criterion is still valid when considering the radiation of atoms in the cavity. Here, we reexamine this topic and give a new but more reasonable criterion to test the collective radiation of multi atoms in the cavity. We tend to use the witness parameter WN as the criterion of superradiance. More importantly, as the frequency of the driving field is easy to adjust in the experiment, the radiation power of the atom in the cavity is calculated under the action of the coherent driving field, and the optimal frequency is given, that is, the single atom radiation and multi-atom radiation are enhanced at the same time. With such new criterion, we find it is impossible to get the superradiance in good cavity. On the contrary, superradiance is much easier to be reached in a bad cavity. We take the cases of one atom, two atoms, three atoms and four atoms for example. Anyway, the irradiation of atoms is non-classical whether it is subradiation or superradiation. The radiation power of the system can be significantly increased by simply increasing the number of atoms. These theoretical results can be realized by using the existing technology, which can make people understand the theory of multi-atom superradiance more clearly and stimulate future experiments.

Precipitation in reactor pressure vessel steels under ion and neutron irradiation: On the role of segregated network dislocations

The ultrahigh density of Mn-Ni-Si-Cu precipitates that form in irradiated reactor pressure vessels (RPV) result in hardening and embrittlement, which may limit the service life of aging nuclear reactors. Here, we quantitatively analyze solute segregation to, and precipitation on, network dislocations in irradiated low alloy RPV steels. The analysis is based on a broad thermodynamic framework, which allows proper identification of possible non-equilibrium perturbative effects of irradiation, like radiation induced segregation (RIS). For the first time, we quantify the segregation of Cu, Mn, Ni and Si to ≈ 5–10 nm network dislocation segments, typically separated by a string-of-pearl type array of MnNiSi precipitates (MNSPs); the MNSPs are appended to Cu rich co-precipitates (CRPs) in steels bearing this element. Detailed atom probe tomography (APT) data are reported for 16 RPV steels, with a wide matrix of tailored compositions, irradiated by both neutrons and 6.4 MeV Fe3+ ions at 320 and 290 °C, respectively. A key aspect of this study is that the very high displacement per atom (dpa) doses and radiation enhanced diffusion (RED) result in nearly full phase separation, allowing isolation of thermodynamic (equilibrium or non-equilibrium) effects. We characterize segregation and precipitates with a comprehensive set of descriptors under both ion and neutron irradiation, including: a) solute enrichment factors (EFs) at dislocations, as a function of alloy composition; and, b) matrix versus dislocation precipitates and their respective characteristics. Formation of these dislocation features can be due to RIS, or thermodynamic in origin, or both. Coupled with simple models, we show that the nucleation MNSP features in low Cu steels is enhanced by segregation. However, in typical supersaturated RPV steels, rapid growth of the precipitates is thermodynamically driven to a quantitatively predictable, nearly full phase separation mole fraction.

Collective Radiation of Multi-Atom in Cavity Under the External Driving Field

There were several works concerning the collective radiation of two atoms in a cavity. According to their respective criteria, they all claim to have reached superradiation in a cavity (See paragraph 3 of the introduction for details). Here, we reexamine this topic and give a new but more reasonable criterion to test the collective radiation of multi atoms in the cavity. We tend to use the witness parameter Wn as the criterion of superradiance. With such new criterion, we find it is impossible to get the superradiance in good cavity. On the contrary, superradiance is much easier to be reached in a bad cavity. We take the cases of one atom, two atoms, three atoms and four atoms for example. These theoretical results can be realized by using the existing technology, which can make people understand the theory of multi-atom superradiance more clearly and stimulate future experiments.

Numerical studies of the saturated absorption resonances in a nonlinear spectroscopy of the degenerate atomic transitions

The physical processes forming the saturated absorption resonance spectra at a number of degenerate atomic transitions at their interaction with coherent optical fields and incoherent ield of spontaneous radiation of excited atoms are studied numerically. The features of behavior of nonlinear resonance spectra depending on the degree of degeneration and relaxation parametersof level transitions, character of polarizations and intensities, as well as direction of propagation of optical fields are analyzed.

Account of Mutual Element Interference in the Analysis of Thin Bilayer V−Cr Systems by X-Ray Fluorescence

A method is proposed for the determination of the surface density of layers in the X-ray fluorescence analysis of bilayer V−Cr systems on polikor substrates. Easy-to-make unified film layers obtained by the deposition of vanadium on polymer film substrates are used. Correction coefficients taking into account the level of intensity attenuation of the primary radiation of an X-ray tube and of the analytical line of an element of the lower layer in the upper layer, and also the enhancement of the fluorescence intensity of atoms of the upper layer by the radiation of atoms of the lower layer are calculated.

Relaxation of interacting open quantum systems

We consider the transition from the description of a closed quantum system consisting of an open quantum system and a reservoir to the description of the open quantum system alone by eliminating the reservoir degrees of freedom by averaging over them. An approach based on the Lindblad master equation for the density matrix is used. A general scheme is developed for deriving the Lindblad superoperator that emerges after averaging the von Neumann equation over the reservoir degrees of freedom. This scheme is illustrated with the cases of radiation of a two-level atom into free space and the dynamics of the transition of a two-level atom from a pure state to a mixed state due to interaction with a dephasing reservoir. Special attention is paid to the open system consisting of several subsystems each of which independently interacts with the reservoir. In the case of noninteracting subsystems, the density matrix is a tensor product of the subsystem density matrices, and the Lindblad superoperator of the system is a sum of Lindblad superoperators of those subsystems. The interaction between the subsystems results not only in the emergence of the corresponding term in the Hamiltonian of the combined system but also in the nonadditivity of the Lindblad superoperators. This is often overlooked in modern literature, possibly leading, as is shown in this methodological note, to serious errors; for example, the second law of thermodynamics could be violated.

Regarding the Main Spectral Lines of a Two-dimensional Two-Electron Atom

The energy of a two-dimensional two-electron atom is calculated in its lowest excited states; together with the previously calculated energy in the ground state, this makes it possible to find the screening constant σ in the lowest excited state and the fundamental frequencies of radiation of such atoms (for example, Не), which can, in principle, be obtained in the Bose condensate phase as has already been done with Na atoms. The possibility of experimental verification of the results is indicated. Errors incurred by other authors in their calculations of σ in the excited state of the two-dimensional He atom are also pointed out.

Fast density reconstruction of Li-BES signal on the COMPASS tokamak.

This article describes a fast and automatic reconstruction of the edge plasma electron density from the radiation of energetic Li atoms of the diagnostic beam on the COMPASS tokamak. Radiation is detected by using a CCD camera and by using an avalanche photo-diode system with a temporal resolution of 20 ms and 2 μs, respectively. Both systems are equipped with a 670.8 nm optical filter which corresponds to the lithium 1s22s1-1s22p1 transition. A theoretical model and a data processing procedure of a raw signal to obtain the density profile are described. The reconstruction algorithm provides the absolutely calibrated electron density profiles together with the measurement error estimated from relatively calibrated light profiles; the implementation is performed in Python. Time demanding operations of the code were optimized to provide reconstruction of a single profile within less than 10 ms which makes the code applicable for processing of a large amount of data. Thanks to this calculation speed, it is possible to reconstruct electron density profiles between two consecutive shots on the COMPASS tokamak with 2 μs time resolution.

Radiation of high-Z atoms sputtered by plasma

In this paper we apply a time-dependent radiative-collision model for analysis of radiation of impurity atoms sputtered in uniform plasma. As an example we consider spectroscopy data of neutral molybdenum atoms sputtered in argon plasma at PR-2 linear plasma device. We use effective collision strengths for electron impact excitation/de-excitation and spontaneous emission obtained earlier by relativistic R-matrix calculations. The ionization rates resolved by excited levels are estimated by the approximate ECIP method. The main feature of the experimental spectra is the maximum of radiation intensity situated at a noticeable distance from the target surface, different for different wavelength. This feature is reproduced by our calculations proving that appearance of the maximum is due to slow excitation of some levels. In contrast to the previous works on the problem, we demonstrate that neither electron-impact ionization nor escape of atoms from the plasma column are necessary for appearance of the maximum. We also show that if the initial population of atoms in excited state exceeds a certain limit, 5% in our particular case, the maximum disappears completely, giving the upper estimate of the initial population.

Emission of fast hydrogen atoms at a plasma–solid interface in a low density plasma containing noble gases

The source of the broad radiation of fast hydrogen atoms in plasmas containing noble gases remains one of the most discussed problems relating to plasma–solid interface. In this paper, we present a detailed study of Balmer lines emission generated by fast hydrogen and deuterium atoms in an energy range between 40 and 300 eV in a linear magnetised plasma. The experiments were performed in gas mixtures containing hydrogen or deuterium and one of the noble gases (He, Ne, Ar, Kr or Xe). In the low-pressure regime (0.01–0.1 Pa) of plasma operation emission is detected by using high spectral and spatial resolution spectrometers at different lines-of-sight for different target materials (C, Fe, Rh, Pd, Ag and W). We observed the spatial evolution for Hα, Hβ and Hγ lines with a resolution of 50 μm in front of the targets, proving that emission is induced by reflected atoms only. The strongest radiation of fast atoms was observed in the case of Ar–D or Ar–H discharges. It is a factor of five less in Kr–D plasma and an order of magnitude less in other rare gas mixture plasmas. First, the present work shows that the maximum of emission is achieved for the kinetic energy of 70–120 eV/amu of fast atoms. Second, the emission profile depends on the target material as well as surface characteristics such as the particle reflection, e.g. angular and energy distribution, and the photon reflectivity. Finally, the source of emission of fast atoms is narrowed down to two processes: excitation caused by collisions with noble gas atoms in the ground state, and excitation transfer between the metastable levels of argon and the excited levels of hydrogen or deuterium.

The influence of collisions on the temporary shape of stimulated echo hologram in gas

In this paper, we investigate the influence of collisions with the change of particle velocity direction in a gas on the reproduction of the temporary shape of the object laser pulse in the stimulated echo hologram response. Due to such collisions, the frequency shifts of the radiation of atoms in the gas randomly vary (spectral diffusion within the heterogeneously broadened line). It is shown, that such diffusion leads to the not correlated heterogeneous broadening in the gas at the different time intervals and the partial loss of system phase memory, which results in a partial loss of retrieved information encoded in the temporal form of the object laser pulse.