Spectral distribution in the reflection of parametric X-rays

AbstractThe approach for the description of the emission of white and characteristic x-rays from standard x-ray tubes is modified for an application to transmission anodes. This modification is based on the assumption of a negligible penetration depth of the electrons in comparison to the thickness of the anode. The results of our considerations are presented for Cu, Mo and W anodes with two different thicknesses. For comparison, the spectra of standard anodes which have been operated with identically high voltages and anode currents are given. A typical feature of transmission anodes is their spectral hardening of the energy distribution of emitted photons. A further interesting detail is the development of narrow band excitation anodes as can be seen from the results for Mo. With anode thicknesses of approximately 200 μm and a high voltage of 30 kv the spectral distribution is restricted to an energy ranging from 15 to 20 keV.

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An Automatic Stabilized Detection System for Measuring Soft Celestial X-Rays

Symposium - International Astronomical Union ◽

10.1017/s0074180900103559 ◽

1971 ◽

Vol 41 ◽

pp. 211-212

Author(s):

A. J. F. Den Boggende ◽

H. F. Van Beek ◽

A. C. Brinkman ◽

H. Th. J. A. Lafleur

Keyword(s):

Normal Mode ◽

Spectral Distribution ◽

Detection System ◽

X Rays ◽

X Ray

In order to observe celestial X-ray sources an instrument is under development to be launched in the Astronomical Netherlands Satellite (ANS) in 1974. The aim of the experiment is to measure the spectral distribution of the sources. If there is some evidence that a source should be a pulsar the instrument can be switched from the normal mode to the pulsar mode. In this latter mode the detected photons are labeled in time using an on board clock. The ANS will have a pointing mode and a slow scanning mode. The maximum observing time per orbit for one object will be about 2000 s.

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The production mechanism and spectral distribution of K MO X-rays in collisions of 35-200 keV N+-N

Journal of Physics B Atomic and Molecular Physics ◽

10.1088/0022-3700/11/5/020 ◽

1978 ◽

Vol 11 (5) ◽

pp. 865-874 ◽

Cited By ~ 7

Author(s):

T P Hoogkamer ◽

P H Woerlee ◽

F W Saris ◽

W E Meyerhof

Keyword(s):

Spectral Distribution ◽

X Rays ◽

Production Mechanism

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TXRF with Various Excitation Sources

Advances in X-ray Analysis ◽

10.1154/s0376030800013112 ◽

1991 ◽

Vol 35 (B) ◽

pp. 925-931 ◽

Cited By ~ 1

Author(s):

Peter Wobrauschek ◽

Peter Kregsamer ◽

Christina Streli ◽

Robert Rieder ◽

Hannes Aiginger

Keyword(s):

Synchrotron Radiation ◽

High Power ◽

Spectral Distribution ◽

Detection Limits ◽

High Energy ◽

Exciting Radiation ◽

X Rays ◽

Beam Path ◽

X Ray ◽

Excitation Conditions

AbstractImproving the detection limits in TXRF by optimizing the excitation conditions is the goal of this work. The properties of the exciting radiation due to spectral distribution, polarisation, intensity and energy are investigated and compared to find best conditions. Results are given from experiments performed with synchrotron radiation, Bragg polarized monoenergetic x-rays, high energy cut-off reflector in the primary beam path of a high power x-ray tube and several geometries for the sample reflector.

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Surface Characterization by X-Ray Techniques

Advances in X-ray Analysis ◽

10.1154/s0376030800008120 ◽

1975 ◽

Vol 19 ◽

pp. 607-625

Author(s):

Robert L. Park

Keyword(s):

Spectral Distribution ◽

Surface Characterization ◽

Local Density ◽

Surface Region ◽

Mean Free Path ◽

X Rays ◽

X Ray ◽

Line Shapes ◽

Threshold Excitation ◽

High Kinetic Energy

The filled states in the surface region of a solid can be probed by monochromatic x-rays. The spectral distribution of photoelectrons near the high kinetic energy limit is related to the density of valence band states. Complementary information regarding the unoccupied states is obtained from the spectral distribution of bremsstrahlung, emitted bv radiative capture of monoenergetic electrons, near the short wavelength limit. In soft x-ray appearance potential spectroscopy, the near-threshold excitation probability of a core level is a measure of the local density of unfilled states associated with a particular element. In each case the sensitivity to the surface results from the short mean free path for inelastic scattering of electrons. Unfortunatelv this has severe consequences for the interpretation of line shapes.

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The spectral distribution of multiple Compton scattering for X-rays

Philosophical Magazine ◽

10.1080/14786439808206557 ◽

1974 ◽

Vol 30 (2) ◽

pp. 307-317 ◽

Cited By ~ 19

Author(s):

Brian G. Williams ◽

Philip Pattison ◽

Malcolm J. Cooper

Keyword(s):

Compton Scattering ◽

Spectral Distribution ◽

X Rays ◽

Multiple Compton Scattering

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White-Light Coronal Structures: Streamers and CMEs

International Astronomical Union Colloquium ◽

10.1017/s0252921100025045 ◽

1994 ◽

Vol 144 ◽

pp. 82

Author(s):

E. Hildner

Keyword(s):

Emission Line ◽

Electron Density ◽

White Light ◽

Coronal Mass Ejections ◽

X Rays ◽

Solar Cycles ◽

Temperature Function ◽

X Ray ◽

Eclipse Observations ◽

Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

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Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

International Astronomical Union Colloquium ◽

10.1017/s0252921100064630 ◽

2000 ◽

Vol 179 ◽

pp. 263-264

Author(s):

K. Sundara Raman ◽

K. B. Ramesh ◽

R. Selvendran ◽

P. S. M. Aleem ◽

K. M. Hiremath

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Magnetic Flux ◽

Ultra Violet ◽

Active Regions ◽

Morphological Properties ◽

Energy Storage And Conversion ◽

The Sun ◽

X Rays ◽

The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust & Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust & Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

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The Clinical, Roentgenological and Morphological Effects of an Acute Exposure of Phosgene on the Lungs of Dogs

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100065237 ◽

1971 ◽

Vol 29 ◽

pp. 236-237

Author(s):

R. F. Bils ◽

W. F. Diller ◽

F. Huth

Keyword(s):

Latent Period ◽

Chemical Industry ◽

Toxic Substance ◽

Lung Edema ◽

X Rays ◽

Beagle Dogs ◽

Male And Female ◽

Morphological Alterations ◽

Before And After ◽

Electron Microscopes

Phosgene still plays an important role as a toxic substance in the chemical industry. Thiess (1968) recently reported observations on numerous cases of phosgene poisoning. A serious difficulty in the clinical handling of phosgene poisoning cases is a relatively long latent period, up to 12 hours, with no obvious signs of severity. At about 12 hours heavy lung edema appears suddenly, however changes can be seen in routine X-rays taken after only a few hours' exposure (Diller et al., 1969). This study was undertaken to correlate these early changes seen by the roengenologist with morphological alterations in the lungs seen in the'light and electron microscopes.Forty-two adult male and female Beagle dogs were selected for these exposure experiments. Treated animals were exposed to 94.5-107-5 ppm phosgene for 10 min. in a 15 m3 chamber. Roentgenograms were made of the thorax of each animal before and after exposure, up to 24 hrs.

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