scholarly journals Effect of pulsed soft X-ray radiation on the surface topography of some metals

2021 ◽  
Vol 2064 (1) ◽  
pp. 012092
Author(s):  
A E Ligachev ◽  
M V Zhidkov ◽  
S A Sorokin ◽  
G V Potemkin ◽  
Yu R Kolobov
Keyword(s):  
Surface Topography ◽  
Surface Defects ◽  
Radiation Energy ◽  
High Current ◽  
Radiation Energy Density ◽  
Near Surface ◽  
Ion Flow ◽  
X Ray ◽  
Irradiation Energy ◽  
The Impact

Abstract Effect of the pulsed soft X-ray fluxes (PSXF) on the surface topography of metals (Mg and Cu) has been investigated. Soft pulse X-ray irradiation (energy quanta of 0.1-1.0 keV) were carried out on a high-current MIG generator. The sample of magnesium was located at a distance of 10 cm from the X-ray source. Since the distance to the sample significantly exceeded the size of the X-ray beam, it can be assumed that the density of the X-ray radiation flow to the magnesium sample was uniform. The duration of the radiation pulse was 100 ns, and the radiation energy density in the pulse varied from 13 to 19 J/cm2. As a result of melting under the action of PSXF of the near-surface layer of metals and subsequent solidification, a wavy relief is formed on their surface. Defects in the form of craters, which usually occur after the impact of a powerful pulsed ion flow on metals, were not detected.

scholarly journals Calculation of radiation dose enhancement by gadolinium compounds for radiation therapy

2022 ◽  
Vol 2155 (1) ◽  
pp. 012030
Author(s):  
G.A. Abdullaeva ◽  
G.A. Kulabdullaev ◽  
A.A. Kim ◽  
A.F. Nebesny ◽  
D.O. Yuldashev
Keyword(s):  
Radiation Therapy ◽  
Contrast Agent ◽  
Biological Tissue ◽  
Radiation Energy ◽  
Dose Enhancement ◽  
X Ray ◽  
Photon Irradiation ◽  
Irradiation Energy ◽  
Gd Contrast Agent ◽  
Shell Ionization

Abstract In this study, we evaluate the features of dose enhancement with Gd contrast agent (Magnevist). Due to the increased relaxation time and high atomic number (z=64) Gd can be used in radiation therapy as a radiosensitizer. To perform a quantitative evaluation of the radiosensitization effect is determined a parameter called the dose enhancement factor - DEF. The DEF values were calculated based on the analysis of the mass absorption coefficients for gadolinium and biological tissue. An increase in DEF is observed when the radiation energy is higher than the K-shell ionization energy of Gd atoms. For the presence of 20315 ppm Gd contrast agent in biological tissue the dose enrichment factor is maximum DEF = 4.12 at photon irradiation energy 60 keV. Also, based on calculations for photon irradiation sources considered high degrees of dose enhancement occur for Am-241, Yb-196, and 100 kVp X-ray tube.

Measuring the Radiation Energy Density of a Pulsed X-Ray Source

2019 ◽  
Vol 62 (2) ◽  
pp. 232-235
Author(s):  
R. R. Akhmetshin ◽  
E. A. Babichev ◽  
D. N. Grigoriev ◽  
V. R. Groshev ◽  
V. F. Kazanin ◽  
...  
Keyword(s):  
Energy Density ◽  
Radiation Energy ◽  
Radiation Energy Density ◽  
X Ray

Surface modification of WC—3% Co hard alloy by powerful nanosecond ultraviolet laser pulses

2020 ◽  
pp. 11-14
Author(s):  
Yu. A. Zheleznov ◽  
◽  
T. V. Malinsky ◽  
S. I. Mikolutskiy ◽  
V. E. Rogalin ◽  
...  
Keyword(s):  
Hard Alloy ◽  
Radiation Energy ◽  
Laser Pulses ◽  
Incident Radiation ◽  
Impact Zone ◽  
Radiation Energy Density ◽  
Ultraviolet Laser ◽  
Focused Beams ◽  
The Impact

The surface quality of the WC—3% Co hard alloy after modification by focused beams of an ultraviolet laser has been investigated. At radiation energy density E ≥ 1.6 J / cm2, traces of melting with a size of 1—3 μm were found on the alloy surface in the impact zone. An increase in intensity of the incident radiation to E ≈ 6.2 J / cm2 leads to an increase in the concentration of cobalt on the surface from 7 to 10%, while the concentration of carbon decreases from 33 to 18%.

In Situ Spectroscopic Ellipsometry for Real Time Composition Control of Hg1−xcdx Te Grown by Molecular Beam Epitaxy

1997 ◽  
Vol 487 ◽  
Author(s):  
R. Dat ◽  
F. Aqariden ◽  
W. M. Duncan ◽  
D. Chandra ◽  
H. D. Shih
Keyword(s):  
Experimental Data ◽  
Molecular Beam Epitaxy ◽  
Surface Topography ◽  
Spectroscopic Ellipsometry ◽  
Molecular Beam ◽  
Surface Defects ◽  
Spectral Ellipsometry ◽  
Composition Control ◽  
The Impact

AbstractSpectral ellipsometry (SE) was applied to in situ composition control of Hg1−xCdxTe grown by molecular beam epitaxy (MBE), and the impact of surface topography of the Hg1−xCdxTe layers on the accuracy of SE was investigated. Of particular importance is the presence of surface defects, such as voids in MBE- Hg1−xCdx.Te layers. While dislocations do not have any significant impact on the dielectric functions, the experimental data in this work show that MBE- Hg1−xCdxTe samples having the same composition, but different void densities, have different effective dielectric functions.

X-ray-diffraction measurements from imperfect GaAs crystals: Evidence for near-surface defects

1990 ◽  
Vol 42 (8) ◽  
pp. 5093-5099 ◽  
Author(s):  
R. Bloch ◽  
D. Bahr ◽  
J. Olde ◽  
L. Brügemann ◽  
W. Press
Keyword(s):  
Surface Defects ◽  
X Ray Diffraction ◽  
Near Surface ◽  
X Ray

scholarly journals Properties of Impact-Related Pseudotachylite and Associated Shocked Zircon and Monazite in the Upper Levels of a Large Impact Basin: a Case Study From the Vredefort Impact Structure

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1053
Author(s):  
Elizaveta Kovaleva ◽  
Roger Dixon
Keyword(s):  
Impact Crater ◽  
Shock Pressure ◽  
Initial Structure ◽  
Impact Structure ◽  
Near Surface ◽  
X Ray ◽  
Host Rocks ◽  
The Impact

The Vredefort impact structure in South Africa is deeply eroded to its lowermost levels. However, granophyre (impact melt) dykes in such structures preserve clasts of supracrustal rocks, transported down from the uppermost levels of the initial structure. Studying these clasts is the only way to understand the properties of already eroded impactites. One such lithic clast from the Vredefort impact structure contains a thin pseudotachylite vein and is shown to be derived from the near-surface environment of the impact crater. Traditionally, impact pseudotachylites are referred to as in situ melt rocks with the same chemical and isotopic composition as their host rocks. The composition of the sampled pseudotachylite vein is not identical to its host rock, as shown by the micro-X-ray fluorescence (µXRF) and energy-dispersive X-ray (EDX) spectrometry mapping. Mapping shows that the melt transfer and material mixing within pseudotachylites may have commonly occurred at the upper levels of the structure. The vein is spatially related to shocked zircon and monazite crystals in the sample. Granular zircons with small granules are concentrated within and around the vein (not farther than 6–7 mm from the vein). Zircons with planar fractures and shock microtwins occur farther from the vein (6–12 mm). Zircons with microtwins (65°/{112}) are also found inside the vein, and twinned monazite (180°/[101]) is found very close to the vein. These spatial relationships point to elevated shock pressure and shear stress, concentrated along the vein’s plane during impact.

In Situ Spectroscopic Ellipsometry for Real Time Composition Control of Hg1−xCdxTe Grown by Molecular Beam Epitaxy

1997 ◽  
Vol 484 ◽  
Author(s):  
R. Dat ◽  
F. Aqariden ◽  
W. M. Duncan ◽  
D. Chandra ◽  
H. D. Shih
Keyword(s):  
Experimental Data ◽  
Molecular Beam Epitaxy ◽  
Surface Topography ◽  
Spectroscopic Ellipsometry ◽  
Molecular Beam ◽  
Surface Defects ◽  
Spectral Ellipsometry ◽  
Composition Control ◽  
The Impact

AbstractSpectral ellipsometry (SE) was applied to in situ composition control of Hg1−xCdxTe grown by molecular beam epitaxy (MBE), and the impact of surface topography of the Hg1−xCdxTe layers on the accuracy of SE was investigated. Of particular importance is the presence of surface defects, such as voids in MBE- Hg1−xCdxTe layers. While dislocations do not have any significant impact on the dielectric functions, the experimental data in this work show that MBE- Hg1−xCdxTe samples having the same composition, but different void densities, have different effective dielectric functions.

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