Collimation of the circulating beam in the U-70 synchrotron by means of the reflection of particles in crystals with axial orientation

The possibilities of the extraction and collimation of a circulating beam by a new method due to the reflection of particles in crystals with axial orientation were experimentally investigated in the Fall 2010 run at the U-70 synchrotron. Such crystals have positive features, because the axial potential is five times larger than the planar potential. It has been shown that the collimation efficiency can reach 90% due to axial effects in the crystal. Losses of the circulating beam on a collimator have been reduced by several times; this makes it possible to suppress the muon jet near the steel collimator of the circulating beam.     

Vibrational spectra of phenylfluorone and their interpretation

Fourier-transform IR absorption, Raman, and surface-enhanced Raman scattering spectra are presented for phenylfluorone, which is widely used as an analytical reagent in the photometric determination of high-valent metals from Groups III–VI of the Periodic Table. A geometric structure and vibrational frequencies for the phenylfluorone molecule were calculated using a quantum-mechanical density-functional method. An interpretation of its vibrational spectra was proposed for the first time. Spectral effects of phenylfluorone protonation have been studied. The geometry of phenylfluorone adsorbed on the surface of nanostructured silver films was examined.     

SubthresholdK + production in proton-nucleus collisions as a probe for short range nucleon correlations

Double differential cross sections for nearthreshold and subthreshold production ofK ⁺ with momentum 1.28 GeV/c at 10.5 degree on Be, Al and Cu targets had been measured. The experiment was performed with FH Spectrometer at ITEP PS in projectile proton kinetic energy range 2.9 – 1.65 GeV. The performed analysis of the excitation functions and target atomic mass dependencies evidences for high order multinucleon correlations are involved in deep subthreshold kaon production.     

Knockout of deuterons and tritons with large transverse momenta in <Emphasis Type="Italic">pA</Emphasis> collisions involving 50-GeV protons

Formation of the d and t cumulative light nuclear fragments emitted from the nucleus with large transverse momenta at an angle of 35° in the laboratory frame is investigated. The data on collisions of 50-GeV protons with the C, Al, Cu, and W nuclei are collected using the extracted proton beam of the IHEP accelerator and the SPIN detector. The results indicate that the dominant contribution to formation of nuclear fragments comes from the local process of direct knockout from the nucleus.     

Bremsstrahlung in alpha decay reexamined

A high-statistics measurement of bremsstrahlung emitted in the alpha decay of (210)Po has been performed, which allows us to follow the photon spectra up to energies of approximately 500 keV. The measured differential emission probability is in good agreement with our theoretical results obtained within the quasiclassical approximation as well as with the exact quantum mechanical calculation. It is shown that, due to the small effective electric dipole charge of the radiating system, a significant interference between the electric dipole and quadrupole contributions occurs, which is altering substantially the angular correlation between the alpha particle and the emitted photon.     

Synchrotron investigations of Si/Mo/Si…c-Si (100) multilayer nanoperiodic structures

This paper presents the results of the investigation of c-Si/[Si/Mo] _n /Si multilayer nanoperiodic structures by X-ray absorption near-edge structure (XANES) spectroscopy using synchrotron radiation. Changes in the fine structure of XANES MoL _2,3 spectra confirm the formation of the silicide phase on heterophase interfaces Si/Mo/Si due to the solid-phase interactions between silicon and molybdenum layers.     

A comparative study of surface‐enhanced Raman scattering from silver‐coated anodic aluminum oxide and porous silicon

Three types of Ag‐coated arrays from porous anodic aluminum oxide (AAO) were prepared and studied as substrates for surface‐enhanced Raman scattering (SERS). They were compared with Ag‐coated porous silicon (PSi) samples. AAO‐based substrates were prepared by the vapor deposition of silver directly onto the surface of porous AAO with different morphologies of the pores, whereas SERS‐active island films on the PSi were prepared by immersion plating. The resulting metallic nanostructures were characterized by UV‐vis absorption spectroscopy and scanning electron microscopy (SEM). Thermal evaporation leads to the formation of granular arrays of Ag nanoparticles on the surface of AAO. SERS activity of the substrates was tested using water‐soluble cationic Zn(II)‐tetrakis (4‐N‐methylpyridyl) porphyrin (ZnTMPyP4) as a probe molecule. The results indicate that all AAO‐based substrates studied here exhibit some degree of SERS activity. Noteworthy, for excitation at 532 nm, signals from AAO‐based substrates were comparable with those from the PSi‐based ones, whereas for 441.6 nm excitation they were about twice higher. The strongest SERS‐enhancement at 441.6 nm excitationwas provided by the AAO substrates with silver deposited on the monolith (originally nonporous) side of AAO. Preferential SERS‐enhancement of the bands ascribed to the vibrations of the N‐methylpyridinium group of ZnTMPyP4 when going to blue excitation was found. Copyright © 2010 John Wiley & Sons, Ltd.     

Adiabatic evaporation of binary liquid mixtures on the porous ball surface

Measured data for the temperature of a porous spherical surface to which an evaporating binary liquid mixture was supplied are reported. In the experiments, solutions of ethyl and methyl alcohols in water, and also solutions of acetone in water, were used. The concentration of mixture components was varied throughout the widest possible range of X _L = 0–1, and the temperature of dry air flow past the sphere was in the range t ₀ = 15–300 °C. In the present study, a strong influence of the composition of the mixtures on their adiabatic evaporation temperature was established. In the heat- and mass-transfer process, the air temperature is also of paramount importance. An experimental correlation is obtained which generalizes data on adiabatic evaporation temperature in a broad range of component concentrations and temperatures for the experimentally examined binary liquid mixtures. This work was supported by the Russian Foundation for Basic Research (Grant No. 06-08-39002—GFEN).