Peculiarities of neutron irradiation influence on GaP light-emitting structures

GaP LEDs irradiated by reactor neutrons were studied by optical and electrical methods. The observed emission intensity degradation is related with two factors: 1) radiation fields that destroy bond excitons and 2) decrease in the free charge carrier concentration, which is caused by their capture by radiation defects. Study of currentvoltage characteristics at 77 K by highly precession methods has revealed the appearance of N-shaped negative differential region caused by carrier tunneling onto deep levels in quantum wells, which might exist in initial and irradiated p-n structures. In some cases, improvement of current-voltage characteristics after neutron irradiation is observed. An assumption is made about the radiation-stimulated origin of this effect

Thermal stability of Ti-C-Ni-Cr and Ti-C-Ni-Cr-Al-Si nanocomposite coatings

The results of the microstructure, mechanical and tribological properties investigations of Ti-C-Ni-Cr and Ti-C-Ni-Cr-Al-Si nanocomposite coatings based on amorphous carbon in the initial state and after the annealing to 900 °C are presented. The effect of annealing temperature on the microstructure, tribological and mechanical properties of Ti-C- Ni-Cr and Ti-C-Ni-Cr-Al-Si nanostructured coatings is discussed

Investigation of the microstructure, mechanical properties and thermal stability of nanocomposite coatings based on amorphous carbon

The Ti-C-Ni-Cr and Ti-C-Ni-Cr-Al-Si nanocomposite coatings based on amorphous carbon and the nanosized particles were synthesized by magnetron method. The results of the microstructure features and mechanical properties investigations of these coatings are presented. The thermal stability of microstructure and properties of these coatings at tempering up to 900°C were investigated. These coatings have a high (11–18 GPa) hardness, low (μ < 0.2) the coefficient of friction and high thermal stability of the microstructure and properties up to 700°C. The features of elastically stressed state of nanosized particles in these coatings were founded. A high local internal stresses in the TiC nanoscale particles do not observed

Defect concentration in clusters, created by fast-pile neutrons in n-Si (FZ, Cz)

The dependence of concentration of defects on doping level for average cluster in n-Si was calculated. It was shown that in the framework of the Gossick's model the concentration of defects for the average cluster is in inverse proportion to the square of a cluster radius. One obtains the size distribution of defect clusters created by fast neutrons of WWR-M reactor, by the transformation of energy spectrum of the primary knock-on atom in n-Si (FZ, Cz). Threshold energy of defect clusters formation 4.7 keV by comparing n-Si crystals irradiated by deuterons and fast-pile neutrons was calculated

The features of microstructure and mechanical properties of austenitic steel after direct and reverse martensitic transformations

The features of structural states of metastable austenitic steel after thermomechanical treatments, including low-temperature deformation, warm deformation and subsequent annealing are investigated. It is shown that under these conditions the direct (γ → α′) and reverse (α′ → γ) martensitic transformations occur and submicrocrystalline structural states are formed. The proposed thermomechanical treatment allows varying the strength and plastic properties of austenitic steel in a wide range. The strength of steel in submicrocrystalline state is 4–6 times higher than its original value

Silicon detectors for γ-ray and β-spectroscopy

Large active volume Si(Li) detectors were successfully developed for γ-ray spectrometry at room temperature that show a sufficient efficiency and an energy resolution that is better than scintillation detectors. The higher efficiency of the proposed detectors with respect to normal silicon diodes is achieved by increasing the active volume. For this purpose special attention is given to the selection of the initial material which has to show homogeneous electro-physical parameters, low concentration of oxygen impurities and high structural perfection. The technique of using lithium ions is used as these drift into large depths and hence the profile of the impurity distribution is optimized

Radiative recombination in initial and electron-irradiated GaP crystals

Photoluminescence of GaP crystals irradiated by 1 MeV electrons was studied at 4.2 K. Samples were prepared using various technologies and doped by Te, Zn, Mg and N. Emission spectra were analyzed as dependent on the impurity content. Found was the electron irradiation influence on the luminescence intensity and its mechanism. Radiative recombination intensity was shown to recover efficiently within the temperature range 200-600 ºC, and the main annealing stage being at 200-400 ºC

Class I methanol masers in low-mass star formation regions

Four Class I maser sources were detected at 44, 84, and 95 GHz toward chemically rich outflows in the regions of low-mass star formation NGC 1333I4A, NGC 1333I2A, HH25, and L1157. One more maser was found at 36 GHz toward a similar outflow, NGC 2023. Flux densities of the newly detected masers are no more than 18 Jy, being much lower than those of strong masers in regions of high-mass star formation. The brightness temperatures of the strongest peaks in NGC 1333I4A, HH25, and L1157 at 44 GHz are higher than 2000 K, whereas that of the peak in NGC 1333I2A is only 176 K. However, rotational diagram analysis showed that the latter source is also a maser. The main properties of the newly detected masers are similar to those of Class I methanol masers in regions of massive star formation. The former masers are likely to be an extension of the latter maser population toward low luminosities of both the masers and the corresponding YSOs.Comment: 5 pages, 1 figure, Proc. IAU Symp. 287 "Cosmic Masers: from OH to H0". LSR velocities of the HH25 masers, which are presented in Table 1, are correcte

ВЫБОР ПАРАМЕТРОВ ДВУХСИСТЕМНОГО ГРУЗОВОГО ЭЛЕКТРОВОЗА

The paper presents a classification of parameters of electric locomotives with comments about existing restrictions and a block diagram of a dual-system electric locomotive. Variants for formation of a train of freight electric locomotives (multiple locomotive section) are shown based on a flexible type, taking into account different groups of parameters.The authors underline that locomotive’s reliability is assessed by a number of parameters but availability index is most important. This index is calculated for a given period of time between overhauls and is now considered to be normally equal to 0,95. The authors consider this value effective for future as well.В статье приведены классификация параметров электровозов с комментарием по поводу действующих ограничений и структурная схема двухсистемного электровоза. Показаны способы формирования его грузового варианта на базе гибкого типажа с учетом различных групп параметров. При этом подчеркивается, что надежность локомотива оценивают по большому количеству показателей, но главным среди них остается коэффициент готовности, который вычисляется за фиксированный промежуток времени между капитальными ремонтами и на уровне нормы предполагает сейчас 0,95. Эту цифру авторы считают пригодной и на перспективу