Test Beams of the LPI Accelerating Complex Pakhra

Physics of Atomic Nuclei - In this paper, we report the characteristics of the generated beams, the extracted electron beam and the beam of secondary electrons/positrons, of the LPI accelerator...     

Laser-induced cavities and solitons in overcritical hydrogen plasma

A picosecond CO₂ laser was used successfully in a number of experiments exploring advanced methods of particle acceleration [1]. Proton acceleration from gas-jet plasma exemplifies another advantage of employing the increase in laser wavelength from the optical to the mid-IR region. Recent theoretical- and experimental-studies of ion acceleration from laser-generated plasma point to better ways to control the ion beam’s energy when plasma approaches the critical density. Studying this regime with solid-state lasers is problematic due to the dearth of plasma sources at the critical electron density ∼10²¹ cm⁻³, corresponding to laser wavelength λ = 1 μm. CO₂ laser offers a solution. The CO₂ laser’s 10 μm wavelength shifts the critical plasma density to 10¹⁹ cm⁻³, a value attainable with gas jets. Capitalizing on this approach, we focused a circular polarized 1-TW CO₂ laser beam onto a hydrogen gas jet and observed a monoenergetic proton beam in the 1–2 MeV range. Simultaneously, we optically probed the laser/plasma interaction region with visible light, revealing holes bored by radiation pressure, as well as quasi-stationary soliton-like plasma formations. Our findings from 2D PIC simulations agree with experimental results and aid in their interpretation.     

THERMODYNAMIC AND PARTICLE-DYNAMIC STUDIES ON SYNTHESIS OF SILICA NANOPARTICLES USING MICROWAVE-INDUCED PLASMA CVD

1. Introduction1.1 Silica nanoparticles and synthesis methods Silica (SiO2) nanoparticles are widely used in industry asan active filler for polymer reinforcement, a rheologicaladditive in fluids, a free flow agent in powders, and anagent for chemical mechanical polishing during IC (inte-grated circuit) fabrication (Sniegowski & de Boer, 2000).Silica powder is also used for producing silicon carbide(Koc & Cattamanchi, 1998) or opaque silica aerosols (Leeet al., 1995). Many methods can …     

Synthesis and molecular structure of substituted 2-hydroxyperhydro-[1,3,2]dioxaborinino[5,4-<Emphasis Type="Italic">c</Emphasis>]pyridines,perhydro[1,3]dioxano[5,4-<Emphasis Type="Italic">c</Emphasis>]pyridine,and their precursor-4-hydroxy-3-(α-hydroxybenzyl)-1-methyl-4-phenylpiperidine

4,8a-Diphenyl-substituted 2-(2-propoxy)perhydro[1,3,2]dioxaborinino[5.4-c]pyridine was obtained by the condensation of 4-hydroxy-3-(α-hydroxybenzyl)-1-methyl-4-phenylpiperidine with triisopropyl borate, and its 2-hydroxysubstituted analog in the presence of water. 1-Methyl-4,8a-diphenyl-perhidro[1,3]dioxano[5,4-c]pyridine was synthesized by the reaction of the same piperidol with formaldehyde. A comparative study of the molecular structures of the three products was carried out by X-ray crystallography. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, 1726–1735, November, 2008.     

Study of hafnium-oxide coatings by means of nuclear backscattering spectrometry

Single-layer coatings made of hafnium oxide and double-layer structures with an intermediate nickel layer, the total thickness of which is 70 μm, are obtained via plasma spraying with a supersonic jet in a rarefied atmosphere. A nozzle extension capable of implementing a Prandtl–Meyer expansion fan is used to generate nanostructured coatings. The coatings are investigated via the nuclear backscattering of spectrometry 7.6 MeV protons, scanning electron microscopy, X-ray microanalysis, and X-ray diffraction. The studies of the surface and transverse microsection of the coatings indicate that they comprise not only deformed particles of the sprayed powder with sizes of greater than 20 μm but also layers and conglomerates of nanoparticles with sizes of 30–60 nm. Depth profiling of the elemental composition performed by means of the nuclear backscattering spectrometry of protons demonstrates that transition layers exist at the interface between the substrate and coating layers characterizing the average size of the coating microparticles. A comparison of thicknesses defined by two methods allows estimation of the overall porosity of the hafnium-oxide layer. In accordance with X-ray diffraction data, the cubic and monoclinic phases of hafnium oxide with a high fraction of the amorphous component are formed in the coating.     

Nonlinear compression of optical solitons

In this paper, we consider nonlinear Schrödinger (NLS) equations, both in the anomalous and normal dispersive regimes, which govern the propagation of a single field in a fiber medium with phase modulation and fibre gain (or loss). The integrability conditions are arrived from linear eigen value problem. The variable transformations which connect the integrable form of modified NLS equations are presented. We succeed in Hirota bilinearzing the equations and on solving, exact bright and dark soliton solutions are obtained. From the results, we show that the soliton is alive, i.e. pulse area can be conserved by the inclusion of gain (or loss) and phase modulation effects.     

Symplectic supercuspidal representations and related problems

In this paper, we summarize the basic structures and properties of irreducible symplectic supercuspidal representations of GLn(F) over a p-adic local field F with characteristic zero, and explore possible topics for further investigation.     

Momentum dependence of hadronic production of the ?-meson and its width in nuclear matter

Information on the properties of the ? meson in the nuclear environment has been derived from its production in proton collisions with C, Cu, Al, and Au nuclear targets. The experiment was carried out with 2.83?GeV protons at the Cooler Synchrotron COSY, with the ? being detected via its K ^?+? K ^?? decay using the ANKE magnetic spectrometer. The measured dependence of the production cross section on the nuclear mass number has been compared with calculations within three different nuclear models. These suggest a significant broadening of the width of the ? in medium relative to its vacuum value. The ANKE results obtained in the momentum range 0.6?p _? ?c are compared with data from photoproduction experiments at slightly higher momenta.