Thermal effects on the electron capture and beta-decays rates are studied for 56Ni embedded in dense and hot matter of the collapsing core of a massive star. The influence of temperature on the strength distributions of GT transitions is considered in the framework of the Skyrme-TQRPA model. It is shown that thermal effects make possible negative- and low-energy GT transitions which are Pauli blocked at zero temperature. The weak-interaction rates obtained in frames of 10different Skyrme interaction parametrizations are compared with one another and with those from the large-scale shell model calculations.
Show AbstractWithin the framework of the time-dependent perturbation theory, interference effects arising from direct single-photon and resonant two-photon ionization of neon by two-frequency circularly polarized radiation were investigated. Analytical formulas for the differential cross section of the process in multielectron atoms of inert gases were obtained. Calculations were made for neon with radiation parameters experimentally implemented on modern free electron lasers.
Show AbstractIn order to study the stability of the method of local mass ratios in the field of superheavy elements, based on the formula for estimating the residual np-interaction, the binding energies of the nuclei A > 200 are calculated. Comparison with experimental data AME2016 shows high accuracy and stability of the method. The characteristics of α-decay are predicted for Z = 102 − 106 and N = 144 − 157 isotopes.
Show AbstractThe aim of this work is to determine the response function for the dectector of γ-quanta using the GEANT4 Monte-Carlo modeling. This function has 7 components and takes into account the γ-quanta Compton scattering in the detector, as well as the effect of the formation of electron-positron pairs with the possibility of subsequent escape of annihilation photons, and their scattering on the electrons of the scitillator.
Show AbstractThe highly toxic 10Be with a half-life T1/2 = 1,6106 years is formed in reactors structural materials. During the process of radioactive decay 10Be emits only electrons with a 555 keV boundary energy. Long-term and expensive radiochemical procedures are required for its detection and control. We propose to use the activation method for determining the 9Be and 10B concentrations in samples with subsequent recalculation of 10Be activity. To implement the proposed method and determine the contribution of 10Be to the structural materials samples, radioactive wastes samples (50 mg) were irradiated with γ-quanta with a 37 MeV boundary energy and 7Be activity in these samples was determined. The activity of 10Be in the sample with a maximum yield of 7Be was 0.09 Bq/g.
Show AbstractThe relative yields of photoneutron reactions on 89Y isotope were measured at the upper limit of bremsstrahlung photons 55.6 MeV. A comparison of measured relative yields with relative reaction yields calculated on the basis of theoretical photoneutron cross sections from TALYS and CMPR model is given.
Show AbstractParameter distributions for events with W, Z boson and top quark pairs production in ATLAS open data are presented. Comparison of distributions in different ranges of parameters was carried out. Obtained results were compared with public results of ATLAS collaboration.
Show AbstractThe task of B-physics in the ATLAS experiment is the study of hadrons, which include b-quarks, or b-hadrons. For decreasing the events rates are using a trigger system for selecting events. B-physics trigger selects events from two muons with opposite electric charges and threshold values of transverse momentum of 4 or 6 GeV.It is implemented via software algorithms included in the high level trigger(HLT). Monitoring is used to maintain proper operation of the B-physics trigger. There are two types of B-physics trigger monitoring : offline and online monitoring.
Show AbstractToday non-destructive laser effect on tissue is used in many areas of medicine. By creating a laser-induced temperature field in the cartilage, one can achieve structural rearrangements, the formation of pores and even the shape changes due to the relaxation of mechanical stresses. In the process of laser exposure to cartilage, there is a change in the mechanical and optical properties of the tissue, which must be monitored to adjust the mode of exposure. This is conveniently done using the speckle interferometry method, the idea of which is to observe the interference pattern produced by the interaction of monochromatic coherent radiation with biological tissue. The paper presents the results of a study of the temporal and temperature dependences of the contrast function and cross-correlation. These dependencies can serve as a basis for monitoring laser exposure of tissue in real time.
Show AbstractIn medical practice, there is surgical intervention for laser cartilage reshaping, important criteria of this is the viability of cells after procedure. That’s why the reducing of duration and power of laser radiation still a central problem. In present time, nanopartilcles are actively using in medicine, and one of the possible niches theirs using is an amplification of laser heating of biological tissues. In this paper, the photothermal effect of metal oxide bronze nanoparticles (NaxTiO2, KxMoO3, KxWO3, HxMoO3) observed at the heating from -10◦С to +40◦С of pig’s rib cartilage by radiation of Er-doped fiber laser with wavelength 1.56 µm has been studied. Comparison of the values of phototermal effect showed, that the most result of laser heating is observed for the samples of cartilaginous tissue impregnated by KxMoO3 nanoparticles. This paper confirms, that the amplification of laser heating of the samples impregnated by nanoparticles depends not only on photo absorption, but on nanoparticle’s diffusion into biological tissue.
Show AbstractAmong all the technologies of bone implant sterilization the most widely used is the radiation sterilization method with gamma rays or electrons. The determining parameter is the value of the absorbed dose. Dose established by the IAEA for sterilization of bone grafts is 25 kGy. One of the largest problems is the dose reduction while preservation of high sterility of the implants. In order to overcome the above drawbacks, an additional sterilizing factor was proposed to use as a sterilization method comprising treating the implant in two steps with an ozone-air mixture, which reduces radioresistance and reduces the population of microorganisms before subsequent radiation processing. Microbiological studies have confirmed the effectiveness of the developed method.
Show AbstractOne of the most important stages of therapy planning is the visualization of the pathological target and the surrounding healthy tissues. In cases where critical structures are closely adjacent to a tumor, located inside the pathological target in whole or in part (for example, pituitary adenomas, craniopharyngiomas, optic nerve gliomas), determining the outlines of critical structures from a standard set of images is difficult. In this case, for studying the structure of the brain white matter, another MRI modality, called diffusion-weighted (DWI), can be used, which allows for in vivo measurements of white matter fiber orientation based on information about the diffusion of water. An addition to DWI is diffusion-tensor tomography (DTT), capable of producing quantitative maps of microscopic natural displacements of water molecules that occur in tissues as part of the physical diffusion process. However, now the technique has certain limitations. There are three main problems that prevent the use of DWI by clinicians: 1) high number of false-positive results ; 2) the difficulty with crossing, «kissing» and banding fibers; 3) the lack of reproducibility of the result, dependence on the user; 4) the inability to display paths of small length; 5) the instability of algorithms when working with pathologies. One possible approach that is worth paying attention to in order to improve the results may be machine learning, which consists in using a fully convolutional neural network to study fiber orientation maps. The purpose of the report is literature review of the main diffusion model, tractography algorithms and compare software packages based on them for identifying the necessary functionality to create complete software for radiation therapy.
Show AbstractLeksell Gamma Knife frame-based radiosurgery is considered the «gold standard» of neuro radiosurgery. This is due to both the high precision of the radiation treatment and the large amount of the global clinical data gathered over 50 years of using this radiosurgery system. To date, Leksell Gamma Knife Icon is the most modern model of Gamma Knife and provides the ability to conduct a frame -based stereotactic radiation treatment as well as both mask-fixated frameless hypofractionation and radiosurgery . The integrated Cone Beam CT is used for the positional delivery accuracy. Also the CBCT can be used for defining Leksell stereotactic space instead of the traditional stereotactic frame. The purpose of this work is to analyze different studies to investigate the reasons of the observed deviations in the definition of the stereotactic spaces. It was found that the occurrence of the deviations could be associated with the frame placements uncertainties, MR/CT co-registration errors, MRI distortions and the CBCT artifacts.
Show AbstractA software has been developed and verified for numerical modeling of temperature and thermal stress in crystals of a solar pumped solid-state laser resonator with an external sensitizer for a given volume absorption of radiation. A number of meshes were created for verification. It is shown that the developed solver can be used to calculate thermal stress in solar-pumped laser resonators, and its results for test cases are in good agreement with the analytical solution.
Show AbstractThe method of cohesive zones allows us to evaluate the stability of the material, both to the beginning of the growth of an existing crack, and to the occurrence and development of defects in places of stress concentration. The ability to reliably determine the destruction parameters of adhesive joints (AJ) and predict the behavior of structural elements with their use under loading is an important task for the aircraft industry. It is proposed to use in the finite-element 3D model of stratification according to mode I of the AJ sample in the form of a two-console beam, the length of the cohesive zone (lcz) calculated from the experimentally determined parameters — the local interlayer cohesive strength of the material (σIC) and the intensity of release of elastic energy (GIC). The calculated length of the cohesive zone is applied in the model to calculate the minimum number of finite elements at their optimal size, which ensures higher accuracy of calculations of the main parameters of crack resistance of samples of laminated carbon fiber while minimizing the amount of calculations. The objects of study were AJ sheets of aluminum alloy D-16, which were glued together with dispersion-filled adhesives of industrial grades EPK-1, VK-9, and K-300-61, which are widely used as structural adhesives in the production of aerospace structures. As a result of the research, the main parameters of crack resistance were determined and the optimal length of the final cohesive element was selected, and the resulting model accurately describes the process of crack growth. The results obtained correlate well with the results of experiments.
Show AbstractThermally stimulated shape memory effect (TS SME) in polymer composite materials (PCM) and cross linked polymer matrices is the ability of these materials when heated to a certain temperature, the so-called conversion temperature (Tc), easy to change the shape when an external force is applied, spontaneously restore in the absence of a restraining force and fix the modified and restored form upon cooling. The main factors determining the SME in PCM are: • a large value and reversibility of highly elastic deformations of the matrix at Tc> Tg = Th; • elastic deformations of the reinforcing components (fabric, tape); • freezing of highly elastic deformation at T << Tc. A technique has been developed for the rapid assessment of temperature-time and deformation-force parameters of the TS SME using a dynamic mechanical analyzer (DMA). The technique was tested on carbon plastic with a different type of matrix and fabric as reinforcing. In the developed method for the accelerated evaluation of the deformation-force parameters of the TC SME in PCM at the stages of changing, restoring and fixing their shape, the sample sizes are too small. Therefore, the results obtained can be used only with an accelerated selection of the composition of materials and a comparative assessment of the conditions and effectiveness of the manifestation of the TS SME in them.
Show AbstractThis article discusses the phenomenon of sputtering: its application, history and properties. An integral part of which is the basic Zygmund’s theory, which is currently considered to be the main one in the field of ssputtering, since it takes into account the greatest number of nuances of ion sputtering. It states that the coefficient of ion sputtering Y is proportional to the cosine of the sputtering angle theta in the n degree, which depends on mass and charge. That is, theoretically, it should increase with an increase in the energy of the incident particles. When checking this statement at energies of the order of 10 keV, the theory was performed, however, experiments conducted at higher energies (80, 200, 250 and 300 keV) demonstrated that this is not the case, and in the range of 200 - 250 keV there is a significant dip in the value of coefficient.
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