436 research outputs found

    Problems of Training NDT Specialists in Ukraine

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    Comparison of Risk of Money Laundering and Terrorist Abuse in Non-profit Organizations in Some African and Asian Countries

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    Antideuteron production in proton-proton and proton-nucleus collisions

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    The experimental data of the antideuteron production in proton-proton and proton-nucleus collisions are analyzed within a simple model based on the diagrammatic approach to the coalescence model. This model is shown to be able to reproduce most of existing data without any additional parameter.Comment: To appear in Eur. Phys. J A (2002

    Antiproton annihilation on light nuclei at very low energies

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    The recent experimental data obtained by the OBELIX group on pˉ\bar{p}D and pˉ4\bar{p}^4He total annihilation cross sections are analyzed. The combined analysis of these data with existing antiprotonic atom data allows, for the first time, the imaginary parts of the S-wave scattering lengths for the two nuclei to be extracted. The obtained values are: Ima0sc=[0.62±0.02(stat)±0.04(sys)]fmIm a^{sc}_0 = [- 0.62 \pm 0.02 ({stat}) \pm 0.04 ({sys})] fm for pˉ\bar{p}D and Ima0sc=[0.36±0.03(stat)0.11+0.19(sys)]fmIm a^{sc}_0 = [- 0.36\pm 0.03({stat})^{+0.19}_{-0.11}({sys})] fm for pˉ4\bar{p}^4He. This analysis indicates an unexpected behaviour of the imaginary part of the pˉ\bar{p}-nucleus S-wave scattering length as a function of the atomic weight A: Ima0sc|Im a^{sc}_0| (pˉ\bar{p}p) > Ima0sc|Im a^{sc}_0| (pˉ\bar{p}D) > Ima0sc|Im a^{sc}_0| (pˉ4\bar{p}^4He).Comment: 13 pages, 5 figure

    Modeling of ultrasonic signals in diagnostic devices

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    The transition of hardware to digital data processing has several advantages over analog. Digital information can be stored, transmitted and reproduced at any time. Digitalization of data opens up wide possibilities for their application. It is necessary to simulate some components of the circuit to determine their full capabilities in the design of diagnostic devices and systems. For these purposes, there are a number of software tools that allow you to virtually reproduce various processes and event development. On the other hand, there is no one completely universal or correct way to solve a separately set task

    Gravitational resonance spectroscopy with an oscillating magnetic field gradient in the GRANIT flow through arrangement

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    Gravitational resonance spectroscopy consists in measuring the energy spectrum of bouncing ultracold neutrons above a mirror by inducing resonant transitions between different discrete quantum levels. We discuss how to induce the resonances with a flow through arrangement in the GRANIT spectrometer, excited by an oscillating magnetic field gradient. The spectroscopy could be realized in two distinct modes (so called DC and AC) using the same device to produce the magnetic excitation. We present calculations demonstrating the feasibility of the newly proposed AC mode

    Frequency shifts in gravitational resonance spectroscopy

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    Quantum states of ultracold neutrons in the gravitational field are to be characterized through gravitational resonance spectroscopy. This paper discusses systematic effects that appear in the spectroscopic measurements. The discussed frequency shifts, which we call Stern-Gerlach shift, interference shift, and spectator state shift, appear in conceivable measurement schemes and have general importance. These shifts have to be taken into account in precision experiments

    A New Constraint for the Coupling of Axion-like particles to Matter via Ultra-Cold Neutron Gravitational Experiments

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    We present a new constraint for the axion monopole-dipole coupling in the range of 1 micrometer to a few millimeters, previously unavailable for experimental study. The constraint was obtained using our recent results on the observation of neutron quantum states in the Earth's gravitational field. We exploit the ultimate sensitivity of ultra-cold neutrons (UCN) in the lowest gravitational states above a material surface to any additional interaction between the UCN and the matter, if the characteristic interaction range is within the mentioned domain. In particular, we find that the upper limit for the axion monopole-dipole coupling constant is (g_p g_s)/(\hbar c)<2 x 10^{-15} for the axion mass in the ``promising'' axion mass region of ~1 meV.Comment: 5 pages 3 figure

    Quasi-specular albedo of cold neutrons from powder of nanoparticles

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    We predicted and observed for the first time the quasi-specular albedo of cold neutrons at small incidence angles from a powder of nanoparticles. This albedo (reflection) is due to multiple neutron small-angle scattering. The reflection angle as well as the half-width of angular distribution of reflected neutrons is approximately equal to the incidence angle. The measured reflection probability was equal to ~30% within the detector angular size that corresponds to 40-50% total calculated probability of quasi-specular reflection
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