Anticipated X-ray and VUV spectroscopic data from ITERwith appropriate diagnostic instrumentation

2008 ◽  
Vol 86 (1) ◽  
pp. 277-284 ◽  
Author(s):  
N J Peacock ◽  
M G O’Mullane ◽  
R Barnsley ◽  
M Tarbutt
Keyword(s):  
Line Profile ◽  
Atomic Data ◽  
Spectral Signature ◽  
Atomic Collisions ◽  
X Ray ◽  
The Core ◽  
Spectral Bands ◽  
Wide Range ◽  
Core Plasma ◽  
The Continuum

The radiation characteristics of anticipated sample elements, from H through W, in the International Thermonuclear Experimental Reactor (ITER) have been modelled using the diffusion equilibrium model SANCO for the ion concentrations coupled with the spectral signature of the ions, throughout the X-ray and VUV regions (0.1–100 keV), using the Atomic Data and Analysis Structure population code and database, ADAS. The spectral signature varies greatly depending on whether the viewing line-of-sight (LOS) encompasses the divertor and (or) core regions of the plasma volume. Bound–bound transitions required for line profile analyses of nonfuel core ions can locally dominate the continuum spectrum in the 0.1–10 keV region at acceptably low elemental concentrations. While the background continuum is the main source of noise in the line profile analyses, the intensity and features of the continuum when divided into many spectral bands covering 0.1–100 keV are themselves powerful diagnostics of the plasma composition, Zeff, and the electron temperature. The spectral signature of the divertor LOSs where 1 < Te < 300 eV is dominated typically and exclusively by lines in the XUV–VUV region, restricted in the case of W to λ > 40 Å. Appropriate instrumentation, relying on imaging Bragg reflectors and diffractors and position-sensitive energy-resolving detectors, is designed to cover the full spatial extent of the core plasma. Estimates of the core signal/noise based on experience with tritium experiments on the Joint European Torus indicates substantial signal levels with tolerable neutron-induced noise and component degradation. The divertor diagnostics make use of a suite of aspheric diffraction grating spectrometers designed to measure impurity ion influxes and are essential for plasma control. The EBIT could be conceived as a neutron-free adjunct facility to the ITER spectroscopic programme. At its simplest level, it provides standards for instrument performance and for the spectroscopic signature of selected ions subjected to electronic and atomic collisions over a wide range of ITER-relevant impacting energies.PACS Nos.: 52.58.Lq, 52.55.Fa, 52.70–m, 52.25.Vy, 87.64.Gb

scholarly journals One Shot Cluster Based Approach for the Detection of COVID-19 from Chest X-Ray Images

2020 ◽  
Author(s):  
V.N. Manjunath Aradhya ◽  
Mufti Mahmud ◽  
Basant Agarwal ◽  
D.S. Guru ◽  
M. Shamim Kaiser
Keyword(s):  
Virus Disease ◽  
X Rays ◽  
Probabilistic Neural Networks ◽  
X Ray ◽  
The Core ◽  
Wide Range ◽  
Test Instance ◽  
Chest X Ray ◽  
Detection And Diagnosis ◽  
The Way

Corona virus disease (COVID-19) has infected over more than 10 million people around the globe and killed at least 500K worldwide by the end of June 2020. As this disease continues to evolve and scientists and researchers around the world now trying to find out the way to combat this disease in most effective way. Chest X-rays are widely available modality for immediate care in diagnosing COVID-19. Precise detection and diagnosis of COVID-19 from these chest X-rays would be practical for the current situation. This paper proposes one shot cluster based approach for the accurate detection of COVID-19 chest x-rays. The main objective of one shot learning (OSL) is to mimic the way humans learn in order to make classification or prediction on a wide range of similar but novel problems. The core constraint of this type of task is that the algorithm should decide on the class of a test instance after seeing just one test example. For this purpose we have experimented with widely known Generalized Regression and Probabilistic Neural Networks. Experiments conducted with publicly available chest x-ray images demonstrate that the method can detect COVID-19 accurately with high precision. The obtained results have outperformed many of the convolutional neural network based existing methods proposed in the literature.

scholarly journals Extreme-ultraviolet- and X-Ray-driven Photochemistry of Gaseous Exoplanets

2022 ◽  
Vol 3 (1) ◽  
pp. 1
Author(s):  
Daniele Locci ◽  
Antonino Petralia ◽  
Giuseppina Micela ◽  
Antonio Maggio ◽  
Angela Ciaravella ◽  
...  
Keyword(s):  
Cross Sections ◽  
Atmospheric Chemistry ◽  
Extreme Ultraviolet ◽  
X Rays ◽  
Stellar Spectrum ◽  
X Ray ◽  
Spectral Bands ◽  
Wide Range ◽  
Chemical Conditions ◽  
Ultraviolet Photons

Abstract The interaction of exoplanets with their host stars causes a vast diversity in bulk and atmospheric compositions and physical and chemical conditions. Stellar radiation, especially at the shorter wavelengths, drives the chemistry in the upper atmospheric layers of close orbiting gaseous giants, providing drastic departures from equilibrium. In this study, we aim at unfolding the effects caused by photons in different spectral bands on the atmospheric chemistry. This task is particularly difficult because the characteristics of chemical evolution emerge from many feedbacks on a wide range of timescales, and because of the existing correlations among different portions of the stellar spectrum. In describing the chemistry, we have placed particular emphasis on the molecular synthesis induced by X-rays. The weak X-ray photoabsorption cross sections of the atmospheric constituents boost the gas ionization to pressures inaccessible to vacuum and extreme-ultraviolet photons. Although X-rays interact preferentially with metals, they produce a secondary electron cascade able to ionize efficiently hydrogen- and helium-bearing species, giving rise to a distinctive chemistry.

Line Profile Analysis (LPA) Methods: Systematic Ranking of the Quality of their Basic Assumptions

2004 ◽  
Vol 443-444 ◽  
pp. 127-130
Author(s):  
Arnold C. Vermeulen ◽  
Rob Delhez
Keyword(s):  
Line Profile ◽  
Profile Analysis ◽  
Line Profile Analysis ◽  
Line Profiles ◽  
Qualitative Comparison ◽  
New Developments ◽  
X Ray ◽  
Basic Assumptions ◽  
Wide Range

All methods of analyzing the broadening of XRD line profiles have to take into account two basic effects: broadening by the instrument - including the X-ray spectrum - and the characteristics of broadening by size effects and by lattice defects - including their interaction. These effects are handled in practice by a wide range of auxiliary assumptions. In this paper these assumptions and their quality with respect to "appropriateness of purpose" are listed and compared. By systematic ranking of these assumptions in accordance with their quality, a 2-dimensional map can be constructed that visualizes the differences in the quality of the assumptions. This 2-dimensional map brings a new viewpoint to the various methods for line profile analysis, because it enables a qualitative comparison of the assumptions of existing methods and new developments.

scholarly journals An eccentric wave in the circumstellar disc of the Be/X-ray binary X Persei

2020 ◽  
Vol 499 (3) ◽  
pp. 3650-3659
Author(s):  
R K Zamanov ◽  
K A Stoyanov ◽  
U Wolter ◽  
D Marchev ◽  
N A Tomov ◽  
...  
Keyword(s):  
Line Profile ◽  
Emission Lines ◽  
Planetary Rings ◽  
Peak Ratio ◽  
Detailed Understanding ◽  
X Ray ◽  
Innermost Part ◽  
Spectroscopic Observations ◽  
R Ratio ◽  
Wide Range

ABSTRACT We present spectroscopic observations of the Be/X-ray binary X Per obtained during the period 2017 December–2020 January (MJD 58095–58865). In 2017 December, the H α, H β, and He i 6678 emission lines were symmetric with violet-to-red peak ratio V/R ≈ 1. During the first part of the period (2017 December–2018 August), the V/R ratio decreased to 0.5 and the asymmetry developed simultaneously in all three lines. In 2018 September, a third component with velocity ≈250 km s−1 appeared on the red side of the He i line profile. Later, this component emerged in H β, accompanied by the appearance of a red shoulder in H α. Assuming that it is due to an eccentric wave in the circumstellar disc, we find that the eccentric wave appeared first in the innermost part of the disc, it spreads out with outflowing velocity vwave ≈ 1.1 ± 0.2 km s−1, and the eccentricity of the eccentric wave is ewave ≈ 0.29 ± 0.07. A detailed understanding of the origin of such eccentricities would have applications to a wide range of systems from planetary rings to AGNs.

scholarly journals Line Profiles of Faculae and Pores

1977 ◽  
Vol 4 (2) ◽  
pp. 255-260
Author(s):  
Edward N. Frazier
Keyword(s):  
Magnetic Flux ◽  
Line Profile ◽  
Continuum Models ◽  
Temperature Structure ◽  
Line Profiles ◽  
The Core ◽  
Entire Line ◽  
Fundamental Reason ◽  
The Continuum ◽  
The Way

Historically, attempts to model the temperature structure of faculae have generally suffered from a rather basic contradiction. Models which were based on center to limb measurements of the continuum contrast of faculae disagree with models that are based on measurements of line profiles in faculae. The “continuum” models predict line weakenings which are of larger amplitude than what is observed, and the “line profile” models predict a continuum contrast that is less than what is observed. Chapman (1976) discusses this problem in some detail. It is the purpose of this paper to show that there is a fundamental reason for this historical contradiction between line profile measurements and continuum contrast measurements: The line profile and the continuum contrast of a given facular are both a function (the two functions are different) of the size of that facula. The first indication of this fact was given by Frazier (1971). Figure 1 shows the contrast of faculae in the core of the line Fe Iλ 525. 0 nm, and in the continuum, as a function of the observed magnetic flux. One can see immediately that the contrast in each channel depends on φ in a much different manner. Therefore, one can conclude that the shape of the entire line profile will vary as a function of φ. On the basis of Figure 1, we must expect that this variation of the line profile will be continuous from infinitesimally small faculae up through very large faculae, and indeed, all the way up to pores.

scholarly journals Investigations of Electron Properties of Carbon Nanotubes Decorated with Platinum Nanoparticles with Their Varying Fraction

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Anna Dobrzańska-Danikiewicz ◽  
Dariusz Łukowiec ◽  
Jerzy Kubacki
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Composition ◽  
Platinum Nanoparticles ◽  
Photoelectron Spectroscopy ◽  
Qualitative And Quantitative Analysis ◽  
X Ray ◽  
Qualitative And Quantitative ◽  
The Core ◽  
Wide Range ◽  
Varying Mass

The paper presents the outcomes of investigations into electron properties and a qualitative and quantitative analysis of the chemical composition of unmodified carbon nanotubes with comparison to nanotubes decorated with platinum nanoparticles. The fabricated nanocomposite materials of the CNT-Pt type differed in a varying mass concentration of platinum nanoparticles (5, 10, and 20% of Pt). X-ray photoelectron spectroscopy (XPS) was employed to examine the structure and to analyse chemical composition. Survey spectra measurements within a wide range of the binding energy of 0–1400 eV were performed in the first phase of the investigations. The core lines of C1s carbon, Pt4f platinum, and O1s oxygen and a valence band were then measured. The chemical composition of the studied materials was determined based on the measured spectra of the core lines. The purpose of the investigations is to determine the effect of platinum nanoparticles on the structure and electron properties of the fabricated CNT-Pt nanocomposites.

Solution Absorptiometry with Beta Excited Sources by Means of Balanced Filters

1968 ◽  
Vol 12 ◽  
pp. 439-445
Author(s):  
William S. Toothacker ◽  
Luther E. Preuss
Keyword(s):  
Solute Concentration ◽  
X Rays ◽  
X Ray ◽  
Straight Line ◽  
Continuum Energy ◽  
Wide Range ◽  
Straight Lines ◽  
Monochromatic Source ◽  
The Continuum ◽  
Versus Concentration

AbstractThe use of beta excited x-ray sources in solution absorptiometry has been reported upon by this laboratory. These sources produce characteristic K x-ray lines superimposed upon a bremsstrahlung continuum. The work previously reported made use of the entire beta excited spectrum. The resulting plots of In (Io/I) versus concentration of solute were not straight lines, (I0is the intensity of the x-rays after passing through the solvent, and I is the intensity after passing through both the solvent and solute), but curved downward, as is characteristic of polychromatic sources due to preferential absorption of the low energy photons. These sources have a bremsstrahlung end-point equal to the beta energy E-max. This continuum energy usually is relatively high, resulting in a high mean x-ray energy for the polychromatic beam. This is not a desirable condition. Ideal sources for absorptiometry would be monochromatic in nature with an overall energy range covering the values for the elements. The use of a monochromatic source has two advantages for solution absorptiometry. First, the sensitivity is much greater since the K peak is of lower energy than the bremsstrahlung continuum. Secondly, the plot of In (Io/I) versus solute concentration is a straight line since a fixed value of the mass absorption coefficient can be assigned to this fixed energy, thus simplifying calibration. To use only the monochromatic K energy from these beta excited sources, we have applied the method of balanced filters. These monochromatic K x-rays, with the remainder of the continuum filtered out, have been employed in solution absorptiometry. The resulting plots of In (Io/I) versus solute concentration are straight lines with very good sensitivity. Using this technique, a very wide range of monochromatic energies are available for use in solution absorptiometry.

Removing Substrate Background in TEM Microanalysis

1974 ◽  
Vol 32 ◽  
pp. 568-569
Author(s):  
John C. Russ ◽  
Nicholas C. Barbi
Keyword(s):  
Electrical Conductivity ◽  
Rapid Growth ◽  
Organic Film ◽  
Absolute Concentration ◽  
Background Signal ◽  
X Ray ◽  
Elemental Concentrations ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
The Continuum

The rapid growth of interest in attaching energy-dispersive x-ray analysis systems to transmission electron microscopes has centered largely on microanalysis of biological specimens. These are frequently either embedded in plastic or supported by an organic film, which is of great importance as regards stability under the beam since it provides thermal and electrical conductivity from the specimen to the grid.Unfortunately, the supporting medium also produces continuum x-radiation or Bremsstrahlung, which is added to the x-ray spectrum from the sample. It is not difficult to separate the characteristic peaks from the elements in the specimen from the total continuum background, but sometimes it is also necessary to separate the continuum due to the sample from that due to the support. For instance, it is possible to compute relative elemental concentrations in the sample, without standards, based on the relative net characteristic elemental intensities without regard to background; but to calculate absolute concentration, it is necessary to use the background signal itself as a measure of the total excited specimen mass.

Microstructure of post-deformed ECAP-Ti investigated by Multiple X-Ray Line Profile Analysis

2006 ◽  
Vol 2006 (suppl_23_2006) ◽  
pp. 129-134 ◽  
Author(s):  
E. Schafler ◽  
K. Nyilas ◽  
S. Bernstorff ◽  
L. Zeipper ◽  
M. Zehetbauer ◽  
...  
Keyword(s):  
Line Profile ◽  
Profile Analysis ◽  
Line Profile Analysis ◽  
X Ray
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