Data acquisition system of the OKA experiment

A data acquisition system of the OKA experiment on studying rare kaon decays on the U-70 accelerator is described. The basis of the blocked data acquisition system was the high-speed multichannel information system MISS with autonomous controllers that read out the front-end electronics in the sequential data reading mode and buffering data during the accelerator burst. Data stored in the buffer memory are read out and processed at the end of the accelerator burst. The DATE package builds subevents from event fragments and events from subevents via the event building network. The event building network with the star topology is made with 1GbE-interfaces and 24 × 1 Gb E-switch. The GlusterFS cluster file system underlies the distributed storage system.     

From single crystals to supported nanoparticles in experimental and theoretical studies of H2 oxidation over platinum metals (Pt, Pd): Intermediates, surface waves and spillover

The present paper reviews our investigations concerning the mechanism of H₂ + O₂ reaction on the metal surfaces (Pt, Pd) at different structures: single crystals (Pt(1 1 1), Pt(1 0 0), Pd(1 1 0)); microcrystals (Pt tips); and nanoparticles (Pd–Ti³⁺/TiO₂). Field electron microscopy (FEM), field ion microscopy (FIM), high-resolution electron energy loss spectroscopy (HREELS), XPS, UPS, work function (WF), TDS and temperature-programmed reaction (TPR) methods have been applied to study the kinetics of H₂ oxidation on a nanolevel. The adsorption of both O₂ and H₂ and several dissociative products (H_ads, O_ads, OH_ads) was studied by HREELS. Using the DFT technique the equilibrium states and stretching vibrations of H, O, OH, H₂O, adsorbed on the Pt(1 1 1) surface, have been calculated depending on the surrounding of the metal atoms. Sharp tips of Pt, several hundreds angstroms in radius, were used to perform in situ investigations of the dynamic surface processes. The FEM and FIM studies on the Pt-tip surface demonstrate that the self-oscillations and waves propagations are connected with periodic changes in the surface structure of nanoplane (1 0 0)-(hex) ↔ (1 × 1), varying the catalytic property of metal. The role of defects (Ti³⁺-□_O) in the adsorption centers formation, their stabilization by the palladium nanoparticles, and then the defects participation in H₂ + O₂ steady-state reaction over Pd–Ti³⁺/TiO₂ surface have been studied by XPS, UPS and photodesorption techniques (PhDS). This reaction seems to involve the “protonate” hydrogen atoms (H⁺/TiO_x) as a result of spillover effect: diffusion of H_ads atoms from Pd particles on a TiO_x surface. The comprehensive study of H₂, O₂ adsorption and H₂ + O₂ reaction in a row: single crystals → tips → nanoparticles has shown the same nature of active centers over these metal surfaces.     

Preparation and application of silica sol-gels based on nepheline

This paper reports on the results of investigations into the development of the methods employed for acid treatment of nepheline and the search for new directions in the use of products obtained in the nepheline processing, which have made it possible to design and implement technologies for producing the aluminum-silicon coagulant/flocculant for water purification, as well as technologies for fabrication and application of nepheline-based silicon-containing thickening agents intended for the simplest water-containing explosives of the “Akvatol” type and others.     

Modernized state primary standards of the units of thermal quantities

The content and results of efforts to modernize the three State Primary Standards of the units of temperature in the 0–3000°C range and also of the standards of thermal conductivity and coefficient of linear expansion of solids, stored at the Mendeleev Research Institute of Metrology, are described. It is shown that, simultaneously with the modernization of the standards, the systems of transmitting the dimensions of the units of the standards to working measuring instruments have also been improved.     

Thermoacoustic energy analysis of transverse-pin and tortuous stacks at large acoustic displacements

A simplified method based on Rayleigh's criterion is developed for evaluating thermoacoustic power conversion in transverse-pin and tortuous stacks. Heat transfer and viscous losses are approximated by steady-flow correlations valid at large acoustic displacements with respect to a longitudinal pitch of a pin stack or a characteristic pore size of a random stack. A Lagrangian approach is employed to calculate temperature fluctuations of oscillating gas parcels inside the stack. A computational example is presented for a stack with an inline pin arrangement placed in a standing acoustic wave. Power conversion and efficiencies are evaluated for conditions relevant to a small-scale system. An indirect comparison is also made between theoretical results and experimental data for a prime mover with a wire mesh stack.     

Spectrometry and Performance Characteristics of a BGO–ФЭУ-165 Scintiblock in a Temperatire Range of +25 to –140°C

The possibility of the joint operation of a -165 photomultiplier based on microchannel plates and a BGO crystal, which are cooled to a temperature required for the operation of a semiconductor Ge detector, is investigated taking into account the temperature dependence of proper PMT characteristics. The system was cooled from room temperature to –140°C for 8 h. The limiting temperature at which the PMT holds its serviceability was determined, and the temperature changes in the spectroscopic characteristics of the system (the energy resolution and signal-to-noise ratio) were studied.     

Flip-chip LEDs with deep mesa emitting at 4.2 µm

The spectral, current-voltage, and emission-current characteristics under forward and reverse biases, and the near-field emission pattern of flip-chip LEDs based on heterostructures with an InAsSb active layer (emission wavelength of 4.2 μm at 300 K) and a mesa of 40–50 μm in depth and 240 μm in diameter are analyzed. The possibility of raising the emission output by varying the configuration of the structure and selecting the optimal operation mode dependently on the working temperature are discussed. Original Russian Text ? N.V. Zotova, N.D. Il’inskaya, S.A. Karandashev, B.A. Matveev, M.A. Remennyi, N.M. Stus’, 2006, published in Fizika i Tekhnika Poluprovodnikov, 2006, Vol. 40, No. 6, pp. 717–723.