[en] The Khlopin Radium Institute prepared on behalf of the IAEA a synthetic mixture of ²³³U, ²³⁶U, ²⁴²Pu and ²⁴⁴Pu isotopes. The isotopic composition and elemental concentration of uranium and plutonium were certified on the basis of analyses done by four laboratories of the IAEA Network, using mass spectrometry with internal standardization. The certified values for ²³³U/²³⁶U ratio and the ²³⁶U chemical concentration have a coefficient of variation of 0.05%. The latter is fixed by the uncertainty in the ²³⁵U/²³⁸U ratio of NBS500 used as internal standard. The coefficients of variation of the ²⁴⁴Pu/²⁴²Pu ratio and the ²⁴²Pu chemical concentration are respectively 0.10% and 0.16% and limited by the uncertainty in the ²⁴⁰Pu/²³⁹Pu ratio of NBS947. This four isotope mixture was used as an internal standard as well as a spike, to analyze 30 batches of LWR spent fuel solutions. The repeatability of the mass spectrometric measurements have a coefficient of variation of 0.025% for the uranium concentration, and of 0.039% for the plutonium concentration. The spiking and treatment errors had a coefficient of variation of 0.048%. (author). Refs, figs and tabs

[en] Experimental study of the nonlinear propagation of near-IR gigawatt femtosecond laser pulses in air in the self-focusing and filamentation regimes have been performed in open air and in laboratory. The influence of the initial geometric divergence (both positive and negative) of the laser beam with an irregular intensity profile on the transverse light energy distribution at the end of the path is studied. It is shown experimentally that the displacement of the filamentation region due to geometric focusing or defocusing, makes it possible to control the number and spatial location of light energy density peaks in the receiving plane. The conditions under which a light filament can be reconstructed after the beam transmission through a linear focal waist are determined. A semi-empirical threshold relation is obtained for the beam focusing force and the beam power, when light beam undergoes filamentation behind the geometric focus of the optical system. (extreme light fields and their applications)

[en] Electron-impact excitation of molecules to long-lived Rydberg states is studied

[en] Quantitative data on the nonlinear absorption cross sections of femtosecond Ti : Sapphire laser pulses in air and water vapour have been obtained. A photoacoustic spectrometer calibrated based on the calculated value of linear absorption of laser pulses with a wavelength of 800 nm and a spectral width of 17.7 nm is used to find the nonlinear absorption cross sections of water vapour and air: σ₂^w = (2.6±0.4) × 10^-55 cm⁴ s and σ₂^a = (8.7±1.0) × 10^-56 cm⁴ s, respectively. Based on measuring the absorption of femtosecond Ti : Sapphire laser pulses with a photoacoustic detector calibrated with the known linear absorption of ruby laser radiation by water vapour in air, the air nonlinear absorption cross section is found to be (8.2±0.9) × 10^-56 cm⁴ s.

[en] The results of studies by spectroscopic ellipsometry of amorphous silicon (α-Si) subjected to low-energy implantation of silver ions are presented. Implantation was carried out with an energy of 30 keV at a fluence range (6.24×10¹²-1.3×10¹⁶) ions/cm² and the current density of (0.1-5) μA/cm² at room temperature of the irradiated substrate Si. For the three implantation fluencies of 3.2×10¹³, 6.2×10¹³ and 1.8×10¹⁴ ions/cm² irradiation were carried out with various ion current densities ranged from 0.1 to 5 ×A/cm². The effect of an increase in the defect generation rate with an increase in the ion current density was observed. (authors)

[en] The molecular dynamics method has been used to consider manybody interactions at the channeling of the ion in a carbon nanotube, and the importance of their accounting has been shown. The effect of the wall elastic perturbation of a nanotube on a channeled particle is studied. It was confirmed that when ion with perturbation of the wall of the carbon nanotube interaction is taken into account, the ion energy loss is reduced by a factor of 1.5-3. It is shown that as the temperature of the nanotube decreases, the effect of ion interaction with wall perturbation acquires a more determinate character. Within the framework of the considered model, electronic stopping power on the electronic subsystem of a carbon nanotube is small compared to energy losses of an ion in elastic collisions on atoms of a nanotube wall. (paper)

[en] We study the X-band EPR spectra of Co²⁺ in single-crystalline Zn_1-xCo_xO (x=0.001-0.075) thin films grown by plasma-assisted molecular beam epitaxy. By analyzing the EPR linewidth behavior we argue that the exchange-narrowing model, usually applied to Mn-based II-VI DMS, fails here and that a combined effect of exchange and dipolar broadening can explain the linewidth variation with Co content and temperature

[en] Metal hybrides are currently being used to store and handle hydrogen and its isotopes. They are also being tested in hydrogen compressors and in heat energy, refrigerators and in hydrogen and thermal storage devices. Metal hydrides have been proposed as one of the possible media for hydrogen storage to overcome the limitations of other techniques in regard to safety hydrogen weight and volume ration. The suitability of metal hybrides as a hydrogen storage media depends on a number of factors such as storage capacity, reactivity with hydrogen at various pressures and temperatures, and the cost of base materials. Magnesium based alloys are promising materials for storing hydrogen. They are generally made by argon melting and no attention has been payed to other fabrication techniques such as mechanical alloying or powder technique

[en] Simulations of gain in recombining laser-produced plasma of Li-like ions of aluminum were performed using the 2-D code GIDRA-2. Symmetrical 4-beam scheme of fiber irradiation was modeled in accordance with experimental arrangement described in Ref. (1). These simulations show good agreement with earlier 1-D simulations for optically thin plasma. Maximal angle-averaged value of gain on 3d_5/2-4f_7/2 transition in Li-like aluminum calculated using Sobolev approximation for photon escape probability and the Doppler line profile was 0.95 cm^-1. These 2-D simulations also show more realistic laser energy absorption (25-30% in 2-D simulations compared to nearly 90% in 1-D simulations and 6% in experiments)

[en] We have obtained and studied the numerical and analytical dependences determining the distance dependences of decreasing sound pressure and orthogonal projections of the vibrational velocity vector for low-frequency signals generated in a waveguide in zones of interference maxima. As applied to a Pekeris waveguide and a multidirectional monopole source, convenient approximating expressions have been found that agree well with the exact decay laws for different vector–scalar field components in these zones.