134 research outputs found

    Sub-wavelength diffraction-free imaging with low-loss metal-dielectric multilayers

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    We demonstrate numerically the diffraction-free propagation of sub-wavelength sized optical beams through simple elements built of metal-dielectric multilayers. The proposed metamaterial consists of silver and a high refractive index dielectric, and is designed using the effective medium theory as strongly anisotropic and impedance matched to air. Further it is characterised with the transfer matrix method, and investigated with FDTD. The diffraction-free behaviour is verified by the analysis of FWHM of PSF in the function of the number of periods. Small reflections, small attenuation, and reduced Fabry Perot resonances make it a flexible diffraction-free material for arbitrarily shaped optical planar elements with sizes of the order of one wavelength.Comment: 5 pages, 4 figure

    Induction of Polymerization of the Surface Nanostructures of the Electrodes by Electric Field

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    The results of experimental studies of the interface of "dielectric liquid - nanostructured metal electrode" after electroconvection is presented. It is discovered the patterns of structuring of areas of polymerization showing disruption of the diffusion layer and the processes of charge injection from the tops of structures. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3636

    Novel Optimized Hybrid Terahertz Photoconductive Antennas

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    We demonstrate the results of on THz emission from hybrid THz photoconductive antenna loaded with silver nanoantenna. The results of experimental investigations are in a good agreement with numerical simulations presented in our recent work. The conversion efficiency reveals over 5-fold improvement at certain frequencies, if compared with similar photoconductive antenna without silver nanoparticles, while previous results for this type of antenna barely exceeded 2-fold conversion efficiency gain. We propose a cost-effective fabrication procedure to realize such hybrid THz antennas with optimized plasmonic nanostructures via thermal dewetting process, which does not require any post processing and makes the proposed solution very attractive for applications

    Superstar in Noncommutative Superspace via Covariant Quantization of the Superparticle

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    A covariant quantization method is developed for the off-shell superparticle in 10 dimensions. On-shell it is consistent with lightcone quantization, while off-shell it gives a noncommutative superspace that realizes non-linearly a hidden 11-dimensional super Poincare symmetry. The non-linear commutation rules are then used to construct the supersymmetric generalization of the covariant Moyal star product in noncommutative superspace. As one of the possible applications, we propose this new product as the star product in supersymmetric string field theory. Furthermore, the formalism introduces new techniques and concepts in noncommutative (super)geometry.Comment: 17 pages, LaTe

    Visualization of metasurface eigenmodes with magnetic resonance imaging

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    The ability to control the electromagnetic near field with metasurfaces offers potential applications over the frequency range from radio frequency to optical domains. In this work, we show an essential feature of metasurfaces, subwavelength field confinement via excitation of a large number of eigenstates in a narrow frequency range, and demonstrate an innovative way of visualizing profiles of metasurface eigenmodes with the aid of a magnetic resonance imaging (MRI) system. We show that by tuning different eigenmodes of the metasurface to the Larmor frequency, we can passively tailor the near-field distribution to adjust the desired pattern of radio-frequency excitation in a MRI experiment. Our work demonstrates a practical nonperturbed rapid way of imaging metasurface eigenmodes

    An algorithm for measuring wind speed based on sampling aerosol inhomogeneities

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    Đ Đ°Đ·Ń€Đ°Đ±ĐŸŃ‚Đ°Đœ Đ°Đ»ĐłĐŸŃ€ĐžŃ‚ĐŒ ĐœĐ° ĐŸŃĐœĐŸĐČĐ” ŃŃĐŒĐżĐ»ĐžŃ€ĐŸĐČĐ°ĐœĐžŃ Đ°ŃŃ€ĐŸĐ·ĐŸĐ»ŃŒĐœŃ‹Ń… ĐœĐ”ĐŸĐŽĐœĐŸŃ€ĐŸĐŽĐœĐŸŃŃ‚Đ”Đč ĐŽĐ»Ń ĐŸĐ±Ń€Đ°Đ±ĐŸŃ‚ĐșĐž ĐžĐ·ĐŸĐ±Ń€Đ°Đ¶Đ”ĐœĐžĐč ĐČ Đ·Đ°ĐŽĐ°Ń‡Đ” Đ»ĐžĐŽĐ°Ń€ĐœĐŸĐłĐŸ ĐžĐ·ĐŒĐ”Ń€Đ”ĐœĐžŃ сĐșĐŸŃ€ĐŸŃŃ‚Đž ĐČДтра ĐČ Đ°Ń‚ĐŒĐŸŃŃ„Đ”Ń€Đ”. ĐŸŃ€ĐŸĐČДрĐșĐ° Ń€Đ°Đ·Ń€Đ°Đ±ĐŸŃ‚Đ°ĐœĐœĐŸĐłĐŸ Đ°Đ»ĐłĐŸŃ€ĐžŃ‚ĐŒĐ° ĐżŃ€ĐŸĐžĐ·ĐČĐŸĐŽĐžĐ»Đ°ŃŃŒ с ĐžŃĐżĐŸĐ»ŃŒĐ·ĐŸĐČĐ°ĐœĐžĐ”ĐŒ ŃĐžĐœŃ‚Đ”Đ·ĐžŃ€ĐŸĐČĐ°ĐœĐœŃ‹Ń… Đ»ĐžĐŽĐ°Ń€ĐœŃ‹Ń… ŃĐžĐłĐœĐ°Đ»ĐŸĐČ Đž ĐœĐ° ĐŽĐ°ĐœĐœŃ‹Ń… ĐœĐ°Ń‚ŃƒŃ€ĐœŃ‹Ń… ĐžĐ·ĐŒĐ”Ń€Đ”ĐœĐžĐč. ĐĐ»ĐłĐŸŃ€ĐžŃ‚ĐŒ ĐŸĐ±Ń€Đ°Đ±ĐŸŃ‚ĐșĐž Đ°ŃŃ€ĐŸĐ·ĐŸĐ»ŃŒĐœŃ‹Ń… ĐżĐŸĐ»Đ”Đč ĐČ ĐșĐŸĐŸŃ€ĐŽĐžĐœĐ°Ń‚Đ°Ń… Â«ĐŽĐ°Đ»ŃŒĐœĐŸŃŃ‚ŃŒ – ĐČŃ€Đ”ĐŒŃÂ» ĐżĐŸĐ·ĐČĐŸĐ»ŃĐ”Ń‚ ŃŃƒŃ‰Đ”ŃŃ‚ĐČĐ”ĐœĐœĐŸ ŃƒĐŒĐ”ĐœŃŒŃˆĐžŃ‚ŃŒ ĐżĐŸĐłŃ€Đ”ŃˆĐœĐŸŃŃ‚Đž Đ»ĐžĐŽĐ°Ń€ĐœĐŸĐłĐŸ ĐČŃ€Đ”ĐŒŃĐżŃ€ĐŸĐ»Ń‘Ń‚ĐœĐŸĐłĐŸ ĐŒĐ”Ń‚ĐŸĐŽĐ° ĐžĐ·ĐŒĐ”Ń€Đ”ĐœĐžŃ сĐșĐŸŃ€ĐŸŃŃ‚Đž ĐČДтра ĐżĐŸ сраĐČĐœĐ”ĐœĐžŃŽ с ĐșĐŸŃ€Ń€Đ”Đ»ŃŃ†ĐžĐŸĐœĐœŃ‹ĐŒĐž ĐŒĐ”Ń‚ĐŸĐŽĐ°ĐŒĐž ĐžĐ·ĐŒĐ”Ń€Đ”ĐœĐžŃ. A digital image processing algorithm based on sampling aerosol inhomogeneities was developed in the applied problem of laser remote sensing for measuring the velocity of wind. Tests of the developed algorithm were conducted for synthetic data from numerical simulations and data measured by a lidar. The algorithm developed performs processing of the field of aerosol backscattering coefficient in “RangeTime” coordinates and sufficiently increases the measurement accuracy in comparison with correlation methods

    Performance of novel VUV-sensitive Silicon Photo-Multipliers for nEXO

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    Liquid xenon time projection chambers are promising detectors to search for neutrinoless double beta decay (0ÎœÎČÎČ\nu \beta \beta), due to their response uniformity, monolithic sensitive volume, scalability to large target masses, and suitability for extremely low background operations. The nEXO collaboration has designed a tonne-scale time projection chamber that aims to search for 0ÎœÎČÎČ\nu \beta \beta of \ce{^{136}Xe} with projected half-life sensitivity of 1.35×10281.35\times 10^{28}~yr. To reach this sensitivity, the design goal for nEXO is ≀\leq1\% energy resolution at the decay QQ-value (2458.07±0.312458.07\pm 0.31~keV). Reaching this resolution requires the efficient collection of both the ionization and scintillation produced in the detector. The nEXO design employs Silicon Photo-Multipliers (SiPMs) to detect the vacuum ultra-violet, 175 nm scintillation light of liquid xenon. This paper reports on the characterization of the newest vacuum ultra-violet sensitive Fondazione Bruno Kessler VUVHD3 SiPMs specifically designed for nEXO, as well as new measurements on new test samples of previously characterised Hamamatsu VUV4 Multi Pixel Photon Counters (MPPCs). Various SiPM and MPPC parameters, such as dark noise, gain, direct crosstalk, correlated avalanches and photon detection efficiency were measured as a function of the applied over voltage and wavelength at liquid xenon temperature (163~K). The results from this study are used to provide updated estimates of the achievable energy resolution at the decay QQ-value for the nEXO design

    Measurement of the CKM angle γγ in B±→DK±B^\pm\to D K^\pm and B±→Dπ±B^\pm \to D π^\pm decays with D→KS0h+h−D \to K_\mathrm S^0 h^+ h^-

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    A measurement of CPCP-violating observables is performed using the decays B±→DK±B^\pm\to D K^\pm and B±→Dπ±B^\pm\to D \pi^\pm, where the DD meson is reconstructed in one of the self-conjugate three-body final states KSπ+π−K_{\mathrm S}\pi^+\pi^- and KSK+K−K_{\mathrm S}K^+K^- (commonly denoted KSh+h−K_{\mathrm S} h^+h^-). The decays are analysed in bins of the DD-decay phase space, leading to a measurement that is independent of the modelling of the DD-decay amplitude. The observables are interpreted in terms of the CKM angle Îł\gamma. Using a data sample corresponding to an integrated luminosity of 9 fb−19\,\text{fb}^{-1} collected in proton-proton collisions at centre-of-mass energies of 77, 88, and 13 TeV13\,\text{TeV} with the LHCb experiment, Îł\gamma is measured to be (68.7−5.1+5.2)∘\left(68.7^{+5.2}_{-5.1}\right)^\circ. The hadronic parameters rBDKr_B^{DK}, rBDπr_B^{D\pi}, ÎŽBDK\delta_B^{DK}, and ÎŽBDπ\delta_B^{D\pi}, which are the ratios and strong-phase differences of the suppressed and favoured B±B^\pm decays, are also reported

    Measurement of forward charged hadron flow harmonics in peripheral PbPb collisions at √sNN = 5.02 TeV with the LHCb detector

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    Flow harmonic coefficients, v n , which are the key to studying the hydrodynamics of the quark-gluon plasma (QGP) created in heavy-ion collisions, have been measured in various collision systems and kinematic regions and using various particle species. The study of flow harmonics in a wide pseudorapidity range is particularly valuable to understand the temperature dependence of the shear viscosity to entropy density ratio of the QGP. This paper presents the first LHCb results of the second- and the third-order flow harmonic coefficients of charged hadrons as a function of transverse momentum in the forward region, corresponding to pseudorapidities between 2.0 and 4.9, using the data collected from PbPb collisions in 2018 at a center-of-mass energy of 5.02 TeV . The coefficients measured using the two-particle angular correlation analysis method are smaller than the central-pseudorapidity measurements at ALICE and ATLAS from the same collision system but share similar features
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