Observation and analysis (synthesis) of X-ray spectrum originated from electron capture of low-energy, highly charged Xeq+ (q = 26–43) ions in single collisions with Ar atom

2002 ◽  
Vol 80 (1) ◽  
pp. 65-81 ◽  
Author(s):  
A A Vasilyev ◽  
H Tawara ◽  
P Richard ◽  
U I Safronova
Keyword(s):  
Excited State ◽  
Electron Capture ◽  
Ground State ◽  
Low Energy ◽  
X Rays ◽  
Direct Transition ◽  
X Ray ◽  
High Energies ◽  
Ionization Limit ◽  
Production Mechanisms

X-rays have been observed in collisions of low-energy (keV/u), highly charged Xeq+ (q = 26–43) ions with neutral Ar atoms. These X-rays are understood to be produced through electron capture by highly charged projectile ions from target atoms, the electrons then cascade down to the ground state. It is clearly noted that the most intense X-ray peaks correspond to M-shell – N-shell transitions with different numbers of M-shell vacancies and that X-ray intensities decrease significantly toward high energies near the ionization limit. This observation indicates that the direct transition of an electron captured in a highly excited state to M-shell vacancies is negligibly small. To obtain a better understanding of X-ray production mechanisms, we tried to synthesize the expected X-ray spectrum and compare that with the observed spectrum. The synthesized spectra were found to reproduce the observed spectra reasonably well. PACS Nos: 32.30Rj, 32.70Cs, 32.80Rm, 34.70+e

scholarly journals Galactic line emission from 1–10 keV

1970 ◽  
Vol 37 ◽  
pp. 385-391
Author(s):  
Gary Steigman ◽  
Joseph Silk
Keyword(s):  
Excited States ◽  
Electron Capture ◽  
Ground State ◽  
Galactic Plane ◽  
Line Emission ◽  
Cosmic Ray ◽  
Low Energy ◽  
X Rays ◽  
Capture Process ◽  
Line Intensities

Calculations are given of K-series X-rays produced by interaction of both low energy cosmic rays and diffuse X-rays above 1 keV with heavier ions present in Hi regions. We further consider electron capture to excited states by cosmic ray nuclei of heavy elements, followed by cascades down to the ground state. It is found that the electron capture process may yield appreciable line intensities in the 1–10 keV range in the galactic plane.

scholarly journals The use of fricke dosimetry for low energy x-rays

2006 ◽  
Vol 49 (spe) ◽  
pp. 17-23 ◽  
Author(s):  
Carlos de Austerlitz ◽  
Viviane Souza ◽  
Heldio Pereira Villar ◽  
Aloisio Cordilha
Keyword(s):  
Ionization Chamber ◽  
Parallel Plate ◽  
Low Energy ◽  
Calibration Factor ◽  
X Rays ◽  
Measuring Systems ◽  
X Ray ◽  
Dose Measurements

The performance of four X-ray qualities generated in a Pantak X-ray machine operating at 30-100 kV was determined with a parallel-plate ionization chamber and a Fricke dosimeter. X-ray qualities used were those recommended by Deutsch Internationale Normung DIN 6809 and dose measurements were carried out with Plexiglas® simulators. Results have shown that the Fricke dosimeter can be used not only for soft X-ray dosimetry, but also for the maintenance of low-energy measuring systems' calibration factor.

A Correction Factor for Effects of Scattered X-rays at Calibration of Ionization Chambers in Low Energy X-ray Standard Fields

2007 ◽  
Vol 44 (2) ◽  
pp. 109-113
Author(s):  
Akihiro NOHTOMI ◽  
Nobuhisa TAKATA ◽  
Takeji SAKAE
Keyword(s):  
Correction Factor ◽  
Low Energy ◽  
X Rays ◽  
Ionization Chambers ◽  
X Ray

A single crystal, linearly polarized Fe 2p X-ray absorption study of gillespite

1998 ◽  
Vol 62 (1) ◽  
pp. 65-75 ◽  
Author(s):  
P. F. Schofield ◽  
G. van der Laan ◽  
C. M. B. Henderson ◽  
G. Cressey
Keyword(s):  
Single Crystal ◽  
Ground State ◽  
Branching Ratio ◽  
Linear Dichroism ◽  
Electronic Charge ◽  
Magic Angle ◽  
X Rays ◽  
X Ray ◽  
Peak Structure ◽  
X Ray Absorption

AbstractThe Fe 2p X-ray absorption spectra of single crystal gillespite, BaFeSi4O10, show a strong linear dichroism, i.e. a large difference in the absorption when measured with the polarization of the X-rays either parallel or perpendicular to the plane of the FeO4 group. The isotropic spectrum, obtained from measurement at the ‘magic angle’, and the polarization dependent spectra have been compared to atomic multiplet calculations and show an excellent agreement with theory. Analysis of the branching ratio, the linear dichroism, and the detailed peak structure confirms that the 5A1 level is the ground state at room temperature and pressure. The 5B2 level is sufficiently low in energy that a distortion of the electronic charge density, induced by increased pressure, may result in a 5B2 ground state.

SOFT X-RAY EMISSION IN THE (1.0–1.5 KEV) WINDOW WITH NITROGEN FILLING IN A LOW ENERGY PLASMA FOCUS

2002 ◽  
Vol 16 (09) ◽  
pp. 309-318 ◽  
Author(s):  
M. SHAFIQ ◽  
SARTAJ ◽  
S. HUSSAIN ◽  
M. SHARIF ◽  
S. AHMAD ◽  
...  
Keyword(s):  
Plasma Focus ◽  
Pressure Range ◽  
Filling Pressure ◽  
Pinhole Camera ◽  
Low Energy ◽  
X Rays ◽  
System Efficiency ◽  
Current Sheath ◽  
Pin Diodes ◽  
X Ray

A study of soft X-ray emission in the 1.0–1.5 keV energy range from a low energy (1.15 kJ) plasma focus has been conducted. X-rays are detected with the combination of Quantrad Si PIN-diodes masked with Al (50 μm), Mg (100 μm) and Ni (17.5 μm) filters and with a pinhole camera. The X-ray flux is found to be measurable within the pressure range of 0.1–1.0 mbar nitrogen. In the 1.0–1.3 keV and 1.0–1.5 keV windows, the X-ray yield in 4π-geometry is 1.03 J and 14.0-J, respectively, at a filling pressure of 0.25 mbar and the corresponding efficiencies are 0.04% and 1.22%. The total X-ray emission in 4π-geometry is 21.8 J, which corresponds to the system efficiency of about 1.9%. The X-ray emission is found dominantly as a result of the interaction of energetic electrons in the current sheath with the anode tip. Images recorded by the pinhole camera confirm the emission of X-rays from the tip of the anode.

Spontaneous Tunnel Transitions Induced by Redistribution of Trapped Electrons over Impurity Centers

1983 ◽  
Vol 38 (9) ◽  
pp. 959-962
Author(s):  
A. A. Berezin
Keyword(s):  
Excited State ◽  
Charge State ◽  
Ground State ◽  
Low Energy ◽  
Energy Photon ◽  
Impurity Site ◽  
The Third ◽  
Tunnel Transition ◽  
Extra Electron ◽  
Impurity Centers

Abstract A system of polyvalent impurity centers in a semiconductor (i.e. Au-centers in Si) is con-sidered. The ground state of the impurity pair Au-(a) + Au° (b), where an extra electron is localized on the site a, may be turned into an excited state due to a change of the charge state of a third nearby impurity site. This happens because of different shifts of the Au--level at sites a and b due to their different distances from the third center. As a result, the original pair is able to reach a new ground state Au° (a) + Au- (b) through a slow spontaneous tunnel transition. The probability of this transition, when it is accompanied by an emission of a low energy photon, is calculated explicitly.

Half-Life Determination of 41Ca and Some Other Radioisotopes

Radiocarbon ◽  
1992 ◽  
Vol 34 (3) ◽  
pp. 436-446 ◽  
Author(s):  
Walter Kutschera ◽  
Irshad Ahmad ◽  
Michael Paul
Keyword(s):  
Mass Spectrometry ◽  
Electron Capture ◽  
Half Life ◽  
Specific Activity ◽  
Low Energy ◽  
X Rays ◽  
Weighted Mean ◽  
Electron Capture Decay

We have performed a new determination of the half-life of 41Ca by measuring the specific activity of an enriched Ca material with known 41Ca abundance. We measured the activity via the 3.3-keV X-rays emitted in the electron capture decay of 41Ca, and the 41Ca abundance was measured by low-energy mass spectrometry. The result, t1/2 = (1.01 ± 0.10) × 105 yr, agrees with the recent ‘geological’ half-life of Klein et al., (1991), t1/2 = (1.03 ± 0.07) × 105 yr, and with the corrected value of Mabuchi et al. (1974), t1/2 = (1.13 ± 0.12) × 105 yr. We recommend the weighted mean of these three measurements, t1/2 = (1.04 ± 0.05) × 105 yr, as the most probable half-life of 41Ca. We also discuss the situation of the radioisotopes, 32Si, 44Ti, 79Se and 126Sn, whose half-lives, though still uncertain, are potentially interesting for future AMS studies and other applications.

Exosat Observations of H2252−035: Pulse Phase and Orbital Phase Dependent Low Energy Absorption and Iron Line Emission

1987 ◽  
Vol 93 ◽  
pp. 281-292
Author(s):  
W. Pietsch ◽  
W. Voges ◽  
E. Kendziorra ◽  
M. Pakull
Keyword(s):  
Energy Absorption ◽  
Line Emission ◽  
Low Energy ◽  
Gas Absorption ◽  
X Rays ◽  
Medium Energy ◽  
Iron Line ◽  
X Ray ◽  
Low Energies ◽  
Optical Light Curve

AbstractThe 805 sec pulsing X-ray source H2252−035 has been observed for 7 h on September 14/15 and on September 17, 1983 in X-rays with the low energy telescope and the medium energy detectors of EXOSAT. While below 2 keV the semiamplitude of the 805 s pulses is ~ 100% in the 2.3–7.9 keV band it is only ~ 40%. X-ray dips that are more pronounced in low energies occur simultaneously with the orbital minimum of the optical light curve. The medium energy spectra during dips with respect to the non dip spectrum can be explained by just enhanced cold gas absorption of an additional absorbing column of 2 1022 cm−2. Model spectra for the 805 s minimum have to include a strong iron emission line at 6.55 keV with an equivalent width of 3 keV in addition to a reduced continuum intensity (radiating area) and enhanced low energy absorption.

Stereochemical alterations of 2E chromium(III) excited-state behavior in dicyanotetraazacyclotetradecane complexes. Ground-state x-ray crystal structures, photophysical behavior, and molecular mechanics simulations of stereochemical effects

1992 ◽  
Vol 31 (14) ◽  
pp. 3091-3103 ◽  
Author(s):  
Ronald B. Lessard ◽  
Mary Jane Heeg ◽  
Tione Buranda ◽  
Marc W. Perkovic ◽  
Carolyn L. Schwarz ◽  
...  
Keyword(s):  
Excited State ◽  
Molecular Mechanics ◽  
Crystal Structures ◽  
Ground State ◽  
State Behavior ◽  
X Ray ◽  
Photophysical Behavior

Low-energy cosmic X-ray measurements

1969 ◽  
Vol 47 (23) ◽  
pp. 2651-2666 ◽  
Author(s):  
A. J. Baxter ◽  
B. G. Wilson ◽  
D. W. Green
Keyword(s):  
Spectral Analysis ◽  
Energy Range ◽  
Crab Nebula ◽  
Spectral Characteristics ◽  
Low Energy ◽  
Data Recovery ◽  
X Rays ◽  
X Ray ◽  
Recovery System ◽  
The Crab Nebula

An experiment is described to investigate cosmic X rays in the energy range 0.25–12 keV. The data-recovery system and methods of spectral analysis are considered. Results are presented for the energy spectrum of the diffuse X-ray component and its distribution over the northern sky down to 1.6 keV with a limited extension at 0.27 keV.In the energy range 1.6 to 12 keV, the spectrum is represented by:[Formula: see text]although separate analyses indicate a flattening below 4.5 keV to give:[Formula: see text]and[Formula: see text]At the lowest energies, the flux appears to increase more rapidly and exhibits some anisotropy in arrival directions related to the gross galactic structure. Spectral characteristics of the Crab Nebula and Cygnus X-2 have also been determined.

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