Results 1 - 10 of 34
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[en] Calculations for the damage of the reactor construction in case of impact from a flying object are made and the strength of the reinforced concrete plates and containments are given. A methodology for the calculation of the damage and strength is suggested. The results show that upon action of instant local pressure in the form of rectangular signal lasting more than 2h/a1 (a1 - velocity of the elastic waves in the construction), the damage is along the lateral surface of a truncated cylinder the upper plane of which is the area of the pressure. The calculation results are compared with experimental data and the application of the suggested methodology has been substantiated
[en] The existence of a function f0(x) element of C[0,1] for which the greedy algorithm in the Faber-Schauder system is divergent in measure on [0,1] is established. It is shown that for each ε, 0<ε<1, there exists a measurable subset E of [0,1] of measure |E|>1-ε such that for each f(x) element of C[0,1] one can find a function f-tilde(x) element of C[0,1] coinciding with f(x) on E, whose greedy algorithm in the Faber-Schauder system converges uniformly on [0,1]. Bibliography: 33 titles
[en] The transverse decoherence of the kicked beam due to amplitude dependent tune shift and the linear and the second order chromaticity are studied. For the kicked beam the closed analytical expression for the beam centroid evolution in subsequent turns is obtained. Analysis of the kicked beam centroid signal on the machine optical characteristics is given.
[en] The most effective way to increase the brilliance of synchrotron light sources is the reduction of beam emittance. Following the recent developments in low emittance lattice design, a new sub-nm emittance lattice based on implementation of multi-band achromat concept and application of longitudinal gradient bending magnets was developed for CANDLE storage ring. The paper presents the main design considerations, linear and non-linear beam dynamics aspects of the new lattice proposed.
[en] The narrow-band N-resonance formed in a Λ system of D1-line rubidium atoms is studied in the presence of a buffer gas (neon) and the radiations of two continuous narrow-band diode lasers. Special-purpose cells are used to investigate the dependence of the process on vapor column thickness L in millimeter, micrometer, and nanometer ranges. A comparison of the dependences of the N-resonance and the electromagnetically induced transparency (EIT) resonance on L demonstrates that the minimum (record) thickness at which the N-resonance can be detected is L = 50 μm and that a high-contrast EIT resonance can easily be formed even at L ≈ 800 nm. The N-resonance in a magnetic field for 85Rb atoms is shown to split into five or six components depending on the magnetic field and laser radiation directions. The results obtained indicate that levels Fg = 2, 3 are initial and final in the N-resonance formation. The dependence of the N-resonance on the angle between the laser beams is analyzed, and practical applications are noted.
[en] The generation of the coherent THz radiation and short pulse synchrotron radiation in dedicated electron storage rings requires the study of non-standard magnetic lattices which provide low momentum compaction factor (alpha) of the ring. In the present paper two low alpha operation lattices based on modification of the original beam optics and implementation of inverse bend magnets are studied for CANDLE storage ring. For considered cases an analysis of transverse and longitudinal beam dynamics is given and the feasibility of lattices is discussed
[en] Recently we have obtained the high-contrast electromagnetically induced transparency resonance on 85Rb and 87Rb D1 line in nanometric-thin cell of L = λ = 794 nm thickness. In present work we exploit the 40% contrast of EIT resonance to study its splitting in a very wide range of a B-field covering, for the first time, 1-1700 G region. Experimental results are fully consistent with the developed theoretical model.
[en] The interaction of rubidium atoms with sapphire cell windows at an interwindow distance L = 40–100 nm is studied. For studies, we used the Faraday rotation (FR) effect (rotation of the plane of radiation polarization in a magnetic field) in a thin rubidium atom vapor column for D1, 2 lines. When L decreases from 100 to 40 nm, a red shift of the FR signal frequency is detected: it increases from 10 to 250 MHz, and the broadening of the low-frequency wing increases to ~1 GHz. The atomic transition Fg = 3 → Fe = 2 for the D1 line of 85Rb is shown to be convenient for such investigations, since it can be spectrally separated from other strongly broadened atomic transitions. Coefficients C3, which characterize the atom–surface interaction for the D1 and D2 lines of Rb, are determined. An additional red frequency shift takes place at a nanocell thickness L < 100 nm when the Rb atom density increases, and this shift is absent at large L. A practical application of an FR signal for measuring strong magnetic fields of several kilogausses is described.
[en] The energy spread of the electron beam in the storage ring is one of the most important parameters that define the linear and nonlinear beam dynamics in the storage ring. It is especially important for advanced electron storage rings operating in femto-slicing or low alpha operation modes where the dispersive effects are the essential part of the beam physics. In this paper the beam rms energy spread measurement based on the analysis of transverse decoherence signal of kicked beam in electron storage rings is studied. The numerical results based on particle tracking simulation for CANDLE project and SLS storage rings are discussed.
[en] In the current paper the numerical simulation results for parallel (decoupled) operation of SASE1 and SASE3 undulator sections of European XFEL are presented. The study was based on the idea of betatron switcher implementation. It was shown that it is possible to avoid energy spread growth in SASE1 and to reach the saturation in SASE3 in desirable range of radiation wavelengths by a trajectory kick before SASE1 and its correction before SASE3. (paper)