Fraunhofer diffraction of light by a slit on an opaque screen located between a vacuum and a homogeneous anisotropic medium in the absence and in the presence of absorption at different orientations ...of the optical axis of the medium relative to the slit is considered. The well-known formula for the diffraction in a vacuum is generalized, with the inclusion of the case of diffraction into a uniaxial anisotropic medium in the absence of absorption. A formula is obtained that makes it possible to determine the directions of the diffraction minima and maxima taking into account this absorption.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Forward transition radiation from relativistic electrons is investigated in an ultrasonic superlattice excited in a finite thickness plate by two acoustic waves. In the quasi-classical approximation ...formulae are derived for the vector potential of the electromagnetic field and for the spectral-angular distribution of the radiation intensity. Zone structures appear in the plate, which makes it possible (by an appropriate choice of the frequencies of the two acoustic waves) to control the spectral-angular distribution of the radiation through changes in the parameters of the medium. The acoustic waves generate new resonance peaks in the spectral and angular distribution of the radiation intensity. The heights of the peaks can be tuned by choosing the parameters of the acoustic waves. Numerical examples are presented for a plate of fused quartz.
Possible scenarios of the Aral Sea crisis solution are discussed, and a new scenario is proposed. Previous scenarios have provided for the transfer of water from Siberian Rivers to Central Asia and ...the restriction of unsustainable expansion of irrigation in this region. The scenario proposed in this paper is partly based on the use of Caspian water evaporators located on the eastern coast of the Caspian Sea. Engineering realization of this scenario needs only the construction of the drainage system for the runoff of Caspian waters to the natural evaporators, between which Kara-Bogaz-Gol is the functioning evaporator. This paper shows that realization of this scenario allows the rescue of the Aral Sea and normalization of the water balance in Central Asia. Under this, as the simulation modeling results show, there exist different versions of the scenario depending on the area of evaporators and restrictions for the runoff of Amu Darya and Syr Darya waters to the irrigation systems. Calculation results show that the Aral Sea could be restored within 90–240 years depending on the scenario versions. With only Kara-Bogaz-Gol as the evaporator, the Aral Sea cannot be restored within a century. Additionally, if the anthropogenic runoff of river waters was decreased by 10 percent, the Aral Sea would be restored over about 90 years. Possible versions of the recovery scenario are discussed and assessed.
Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to ...the recoil proton. The wide-angle Compton scattering polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θ_{cm}^{p}=70°. The longitudinal transfer K_{LL}, measured to be 0.645±0.059±0.048, where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton. However, the observed value is ~3 times larger than predicted by the generalized-parton-distribution-based calculations, which indicates a significant unknown contribution to the scattering amplitude.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
A quite simple procedure for the generation of a polarized antiproton beam could be worked out if antiprotons are produced with some polarization. In order to investigate this possibility ...measurements of the polarization of produced antiprotons have been started at a CERN/PS test beam. The polarization will be determined from the asymmetry of the elastic antiproton scattering at a liquid hydrogen target in the CNI region for which the analyzing power is well known. The data are under analysis and an additional measurement is done in 2018. Details on the experiment and the ongoing data analysis will be given.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Abstract Analytical study and summarization of dynamic and frequency characteristics of the seismic-acoustic vibrations originated by the near and distant earthquakes and other natural and artificial ...seismic processes, as well as information analyses of their duration and repetition were done. These allow the formulation of appropriate technical requirements for seismic recording devices, as well as to analyze and evaluate the possibilities of implementing various methods and devices for recording signals from different seismic-acoustic processes depending also on the seismological and other tasks to be solved and various additional specific requirements. It has been shown, that although the introduction of various methods and devices for the digital recording of seismic signals substantially increased during the last decades in seismology, however, it is not even possible to record seismic signals in their entire possible amplitude-frequency ranges employing a single digital recording device too. It also has been confirmed that the widespread usage of digital recording, transmission, machine processing, and analyzing of seismic signals in most contemporary seismic stations does not reduce the value and does not eliminate the need, but, on the contrary, assumes the conduction of simultaneous analog visible registration of seismic processes to obtain express controlling visible records, provide operational manual express analysis of seismograms.
The lifetime of a Λ particle embedded in a nucleus (hypernucleus) decreases from that of free Λ decay mainly due to the opening of the ΛN→NN weak decay channel. However, it is generally believed that ...the lifetime of a hypernucleus attains a constant value (saturation) for medium to heavy hypernuclear masses, yet this hypothesis has been difficult to verify. This paper presents a direct measurement of the lifetime of medium-heavy hypernuclei that were hyper-fragments produced by fission or break-up from heavy hypernuclei initially produced with a 2.34 GeV photon-beam incident on thin Fe, Cu, Ag, and Bi target foils. For each event, fragments were detected in coincident pairs by a low-pressure multi-wire proportional chamber system. The lifetime was extracted from decay time spectrum formed by the difference of the time zeros between the pairs. The measured lifetime from each target is actually a statistical average over a range of mass with mean about 1/2 of the target mass and appears to be a constant of about 200 ps. Although this result cannot exclude unexpected shorter or longer lifetimes for some specific hypernuclei or hypernuclear states, it shows that a systematic decrease in lifetime as hypernuclear mass increases is not a general feature for hypernuclei with mean mass up to A≈130. On the other hand, the success of this experiment and its technique shows that the time delayed fissions observed and used by all the lifetime measurements done so far on heavy hypernuclei could likely have originated from hyper-fragments lighter than the assumed masses.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
We investigate coherent bremsstrahlung by electrons in a periodically deformed two-dimensional crystal. The formula for the corresponding spectral-angular density of the cross-section is derived for ...an arbitrary deformation field. Applications are given for a graphene sheet.
This work is devoted to the study of various types of radiation (acoustic and electromagnetic waves) caused by a shock wave. It is assumed that these radiations are the result of the vortex motions ...of the gas generated by the shock wave. Waves of different frequencies are emitted from different vortices.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The goal of the P-349 experiment is to test whether 3.5 GeV/c antiprotons produced in high-energy proton-proton collisions are polarized in view of the preparation of a polarized antiproton beam. In ...this article, we present the details of the ongoing analysis focused on the drift chambers calibration and particle identification with DIRC.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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