Electron-based crystalline undulator

We discuss the features of a crystalline undulator of the novel type based on the effect of a planar channeling of ultra-relativistic electrons in a periodically bent crystals. It is demonstrated that an electron-based undulator is feasible in the tens of GeV range of the beam energies, which is noticeably higher than the energy interval allowed in a positron-based undulator. Numerical analysis of the main parameters of the undulator as well as the characteristics of the emitted undulator radiation is carried out for 20 and 50 GeV electrons channeling in diamond and silicon crystals along the (111) crystallographic planes.Comment: 16 pages, 8 figures, Latex, IOP styl

Coherent radiation of an ultra-relativistic charged particle channeled in a periodically bent crystal

We suggest a new type of the undulator radiation which is generated by an ultra-relativistic particle channeled along a periodically bent crystallographic plane or axis. The electromagnetic radiation arises mainly due to the bending of the particle's trajectory, which follows the shape of the channel. The parameters of this undulator, which totally define the spectrum and the angular distribution of the radiation (both spontaneous and stimulated), depend on the type of the crystal and the crystallographic plane (axis), on the type of a projectile and its energy, and on the shape of the bent channel, and, thus, can be varied significantly by varying these characteristics. As an example, we consider the acoustically induced radiation (AIR) which is generated by ultra-relativistic particles channeled in a crystal which is bent by a transverse acoustic wave. The AIR mechanism allows to make the undulator with the main parameters varying in wide ranges, which are inaccessible in the undulators based on the motion of particles in the periodic magnetic fields and also in the field of the laser radiation. The intensity of AIR can be easily made larger than the intensity of the radiation in a linear crystal and can be varied in a wide range by varying the frequency and the amplitude of the acoustic wave in the crystal. A possibility to generate stimulated emission of high-energy photons (in keV - MeV region) is also discussed.Comment: published in J. Phys. G: Nucl. Part. Phys. 24 (1998) L45-L53, http://www.iop.or

Названия морских карт, морских навигационных опасностей, предупреждений и сигналов в украинском языке

Стаття продовжує низку публікацій автора, присвячених вивченню сучасної української навігаційно-гідрографічної термінології. У статті проаналізовано тематичні групи української навігаційно-гідрографічної лексики на позначення морських карт, морських навігаційних небезпек, морських навігаційних попереджень і сигналів, окреслено перспективи подальших лінгвістичних досліджень термінології навігаційно-гідрографічної галузі. Стаття відображає результати наукового аналізу термінів навігаційної гідрографії з погляду їхньої структури та семантики, подає лексико-тематичне групування слів на позначення морських карт, морських навігаційних небезпек, морських навігаційних попереджень і сигналів. У статті зроблено спробу визначити семантичні та словотвірні особливості термінів навігаційно-гідрографічної галузі, з’ясовано класифікаційні ознаки лексичних груп на позначення морських карт, морських навігаційних небезпек, морських навігаційних попереджень і сигналів, виокремлено й систематизовано тематичні підгрупи й мікрогрупи, установлено домінувальний тип семантичних відношень у тематичних групах назв морських карт, морських навігаційних небезпек, морських навігаційних попереджень і сигналів.The article continues the cycle of author’s articles, devoted to the study of the modern navigation and hydrographical terminology. The article deals with the thematic groups of the Ukrainian navigation and hydrographical vocabulary on denotation of the names of sea charts, marine dangers to navigation, marine navigational warnings and signals. Problems of consequent linguistic researches of navigation and hydrographical terminology are defined. The results of semantic and word-formation analysis of the modern navigation and hydrographical terms are represented. The classification of the vocabulary according to thematic groups on denotation of the names of sea charts, marine dangers to navigation, marine navigational warnings and signals is considered. The kernel and periphery of the modern navigation and hydrographical terminology are determined in the given article. An attempt to find out semantic and word-formation peculiarities of the navigation and hydrographical terminology is made in the article. The classification signs of the lexical groups on denotation of the names of sea charts, marine dangers to navigation, navigational warnings and signals are analyzed in the article. Thematic subgroups and microgroups are singled out. It is established that the dominating type of semantic relations in thematic groups on denotation of the names of sea charts, marine dangers to navigation, navigational warnings and signals is a hyperhiponimic relations.Статья продолжает цикл публикаций автора, посвящённых изучению современной украинской навигационно-гидрографической терминологии. В статье проанализированы тематические группы украинской навигационно-гидрографической лексики на обозначение морских карт, морских навигационных опасностей, морских навигационных предупреждений и сигналов, определены перспективы дальнейших лингвистических исследований терминологии навигационно-гидрографической отрасли. Статья отражает результаты научного анализа терминов навигационной гидрографии с точки зрения их структуры и семантики, даёт лексико-тематическую классификацию слов на обозначение морских карт, морских навигационных опасностей, морских навигационных предупреждений и сигналов. В статье сделана попытка определить семантические и словообразовательные особенности терминов навигационно-гидрографической отрасли, определены классификационные признаки лексических групп на обозначение морских карт, морских навигационных опасностей, морских навигационных предупреждений и сигналов, выделены и систематизированы тематические подгруппы и микрогруппы, установлен доминирующий тип семантических отношений в тематических группах морских карт, морских навигационных опасностей, морских навигационных предупреждений и сигналов

The Usage of Radiointerpherometric Method Under the Execution of Highly Accurate Geodesic Tasks

Розглянуто теоретико-методичні та науково-практичні аспекти застосування методу радіоінтерферометрії з наддовгими базами (РНДБ-методу). Особливу увагу приділено практичним напрямам застосування цього методу. Окремо окреслено коло питань, що можуть вирішуватися за допомогою РНДБ-методу, і перспективи його використання в практиці геодезичних та землевпорядних робіт.Theoretical-methodical and scientific-practical aspects of the usage of radiointerpherometric method with overlong bases (ROLB-method) are studied in this paper. Special attention is paid to practical directions of the usage of this method. The range of questions that can be solved with the help of ROLBmethod and the prospects of its usage in the practice of geodesic and land managing tasks are separated

The physical properties of AM CVn stars: new insights from Gaia DR2

AM CVn binaries are hydrogen deficient compact binaries with an orbital period in the 5-65 min range and are predicted to be strong sources of persistent gravitational wave radiation. Using Gaia Data Release 2, we present the parallaxes and proper motions of 41 out of the 56 known systems. Compared to the parallax determined using the HST Fine Guidance Sensor we find that the archetype star, AM CVn, is significantly closer than previously thought. This resolves the high luminosity and mass accretion rate which models had difficulty in explaining. Using Pan-STARRS1 data we determine the absolute magnitude of the AM CVn stars. There is some evidence that donor stars have a higher mass and radius than expected for white dwarfs or that the donors are not white dwarfs. Using the distances to the known AM CVn stars we find strong evidence that a large population of AM CVn stars have still to be discovered. As this value sets the background to the gravitational wave signal of LISA, this is of wide interest. We determine the mass transfer rate for 15 AM CVn stars and find that the majority have a rate significantly greater than expected from standard models. This is further evidence that the donor star has a greater size than expected.Comment: Accepted by A&A in main journa

Primjena nove smjese i tehnologije granulacije sirovine za proces sinterovanje željezne rude

This paper presents a new technology for preparing the mixture for iron ore sintering process. The nature of component mixing and granulation has been discussed. The application of the intensive mixer in the preparation of the process components has been shown. The results of the analysis of the sintering mixture granulation process using laboratory installation for mixing and granulation have been presented.Članak donosi nove tehnologije za primjenu smjese za sinterovanje željezne rude. Raspravljena je priroda komponenti smjese i granulacija. Prikazana je intenzivna primjena smjese u pripremnom procesu komponenti. Prikazani su, rabljenjem laboratorijske opreme za smjesu i granulaciju, rezultati analiza granulacije sinterovane smjese

Diabetic Erythrocytes Test by Correlation Coefficient

Even when a healthy individual is studied, his/her erythrocytes in capillaries continually change their shape in a synchronized erratic fashion. In this work, the problem of characterizing the cell behavior is studied from the perspective of bounded correlated random walk, based on the assumption that diffractometric data involves both deterministic and stochastic components. The photometric readings are obtained by ektacytometry over several millions of shear elongated cells, using a home-made device called Erythrodeformeter. We have only a scalar signal and no governing equations; therefore the complete behavior has to be reconstructed in an artificial phase space. To analyze dynamics we used the technique of time delay coordinates suggested by Takens, May algorithm, and Fourier transform. The results suggest that on random-walk approach the samples from healthy controls exhibit significant differences from those from diabetic patients and these could allow us to claim that we have linked mathematical nonlinear tools with clinical aspects of diabetic erythrocytes’ rheological properties

Total spectrum of photon emission by an ultra-relativistic positron channeling in a periodically bent crystal

We present the results of numerical calculations of the channelling and undulator radiation generated by an ultra-relativistic positron channelling along a crystal plane, which is periodically bent. The bending might be due either to the propagation of a transverse acoustic wave through the crystal, or due to the static strain as it occurs in superlattices. The periodically bent crystal serves as an undulator. We investigate the dependence of the intensities of both the ordinary channelling and the undulator radiations on the parameters of the periodically bent channel with simultaneous account for the dechannelling effect of the positrons. We demonstrate that there is a range of parameters in which the undulator radiation dominates over the channelling one and the characteristic frequencies of both types of radiation are well separated. This result is important, because the undulator radiation can be used to create a tunable source of X-ray and gamma-radiation.Comment: published in J. Phys. G: Nucl. Part. Phys. 26 (2000) L87-L95, http://www.iop.org ; 12 pages, 4 figures, LaTe

Formalism of collective electron excitations in fullerenes

We present a detailed formalism for the description of collective electron excitations in fullerenes in the process of the electron inelastic scattering. Considering the system as a spherical shell of a finite width, we show that the differential cross section is defined by three plasmon excitations, namely two coupled modes of the surface plasmon and the volume plasmon. The interplay of the three plasmons appears due to the electron diffraction of the fullerene shell. Plasmon modes of different angular momenta provide dominating contributions to the differential cross section depending on the transferred momentum.Comment: 11 pages, 2 figures; submitted to the special issue "Atomic Cluster Collisions: Structure and Dynamics from the Nuclear to the Biological Scale" of Eur. Phys. J.