Optical recording of information pits in thin layers of chalcogenide semiconductors

The paper is devoted to the theoretical consideration of the question how to record pits with the necessary height profile in photosensitive materials by varying their heat conductivity, photosensitivity, optical absorption, as well as the recording gaussian beam intensity, radius and exposure time. A rather simple analytical expression for the height profile of pits has been derived. It has been shown that this profile depending on photosensitive material parameters and recording beam characteristics could be almost rectangular, flat with rounding edges, spherical or parabolic. The proposed model describes adequately the height profile of pits recorded in thin layer chalcogenide semiconductors by a gaussian laser beam

Recording the high efficient diffraction gratings by using He-Cd laser

High efficient holographic diffraction gratings with spatial frequencies from 600 to 3600 mm⁻¹ have been recorded using As₄₀S₆₀–хSeх (х = 0, 10, 20) photoresist layers and He-Cd laser operating at the wavelength λ = 440 nm. The investigation of the grating relief made by atomic force microscopy revealed that As₄₀S₆₀–хSeх resists allows one to record grating originals with profiles of various heights depending on the resist chemical composition, its etching and exposure times. We obtained typical spectral and angular dependences of the first order diffraction efficiency for the grating with the high modulation depth and groove profile close to the sinusoidal one. Comparing the recorded gratings with different spatial frequencies, exposure and etching times, we determined optimal recording conditions (exposure and etching times) in order to obtain gratings with the high diffraction efficiency

Search for narrow resonances in e+ e- annihilation between 1.85 and 3.1 GeV with the KEDR Detector

We report results of a search for narrow resonances in e+ e- annihilation at center-of-mass energies between 1.85 and 3.1 GeV performed with the KEDR detector at the VEPP-4M e+ e- collider. The upper limit on the leptonic width of a narrow resonance Gamma(R -> ee) Br(R -> hadr) < 120 eV has been obtained (at 90 % C.L.)

Study of operating modes of STRAUS-R accelerator

The description of a pulsed electron accelerator STRAUS-R (3.5 MeV, 60 kA, 60 ns) and results of its experimental research for two operation modes are given. In the mode of electron beam focusing the accelerator provides the focal spot of 3-4 mm diameter on a target and maximum exposure dose of 27 R at 1-m distance from the output window. In the irradiating mode the maximum dose achieves 36 R at 1-m distance from the target with inhomogeneity ≤ 30% within the area 0.36 m² (irradiation spot diameter is 0.6 m).Приведены описание и результаты исследований импульсного электронного ускорителя СТРАУС-Р (3,5 МэВ, 60 кА, 60 нс) в двух режимах его работы. В режиме фокусировки электронного пучка ускоритель обеспечивает получение на мишени фокусного пятна диаметром 3…4 мм при максимальной дозе тормозного излучения 27 Р на расстоянии 1 м от выходного фланца. В облучательном режиме максимальная доза тормозного излучения на расстоянии 1 м от мишени по оси ускорителя достигает 36 Р с неоднородностью ≤ 30% на площади 0,36 м² (диаметр пятна облучения 0,6 м).Наведено опис і результати досліджень імпульсного електронного прискорювача СТРАУС-Р (3,5 МеВ, 60 кА, 60 нс) у двох режимах його роботи. У режимі фокусування електронного пучка прискорювач забезпечує одержання на мішені фокусної плями діаметром 3...4 мм при максимальній дозі гальмівного випромінювання 27 Р на відстані 1 м від вихідного фланця. При опроміненні максимальна доза гальмового випромінювання на відстані 1 м від мішені по осі прискорювача досягає 36 Р с неоднорідністю ≤ 30% на площі 0,36 м² (діаметр плями опромінення 0,6 м)

Measurement of RudsR_{\text{uds}} and RR between 3.12 and 3.72 GeV at the KEDR detector

Using the KEDR detector at the VEPP-4M $e^+e^-$ collider, we have measured the values of $R_{\text{uds}}$ and $R$ at seven points of the center-of-mass energy between 3.12 and 3.72 GeV. The total achieved accuracy is about or better than $3.3\%$ at most of energy points with a systematic uncertainty of about $2.1\%$. At the moment it is the most accurate measurement of $R(s)$ in this energy range

Domain Decomposition Approach for Automatic Parallel Generation of 3D Unstructured Grids

The desire to simulate more and more geometrical and physical features of technical structures and the availability of parallel computers and parallel numerical solvers which can exploit the power of these machines have lead to a steady increase in the number of grid elements used. Memory requirements and computational time are too large for usual serial PCs. An a priori partitioning algorithm for the parallel generation of 3D nonoverlapping compatible unstructured meshes based on a CAD surface description is presented in this paper. Emphasis is given to practical issues and implementation rather than to theoretical complexity. To achieve robustness of the algorithm with respect to the geometrical shape of the structure authors propose to have several or many but relatively simple algorithmic steps. The geometrical domain decomposition approach has been applied. It allows us to use classic 2D and 3D high-quality Delaunay mesh generators for independent and simultaneous volume meshing. Different aspects of load balancing methods are also explored in the paper. The MPI library and SPMD model are used for parallel grid generator implementation. Several 3D examples are shown