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.

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 ‘Local’ Theories of the X-Ray Background

1973 ◽  
Vol 55 ◽  
pp. 258-275 ◽  
Author(s):  
James E. Felten
Keyword(s):  
Intergalactic Medium ◽  
Galactic Plane ◽  
Cosmic Ray ◽  
Seyfert Galaxies ◽  
X Rays ◽  
Statistical Fluctuations ◽  
Galactic Emission ◽  
Diffuse Background ◽  
The Galaxy ◽  
X Ray Background

Recent theories of the origins of diffuse-background X-rays are reviewed, with emphasis on theories of the soft flux in the galactic plane and at the poles. This is probably partly galactic and partly extragalactic in origin. Failure to observe absorption by the Small Magellanic Cloud and by galactic gas in neighboring directions may be due to sources in the Cloud and to statistical fluctuations in galactic emission and absorption. Several models for numerous low-luminosity sources in the Galaxy are available. True ‘diffuse’ emission seems unnecessary. Absorption by Galactic gas seems to agree roughly with theory. The soft extragalactic component may arise in a hot intergalactic medium.The existence of a ‘diffuse’ galactic-plane excess in 1–100 keV is in some doubt. Low-luminosity sources may contribute to this as well.For isotropic X-rays in 1 keV – 1 MeV, superposition theories involving clusters of galaxies, Seyfert galaxies, etc. over a cosmological path length are now roughly viable. Simple ‘metagalactic’ Compton theories seem excluded if the break at 40 keV is sharp, but this is now in doubt. A very hot intergalactic medium at T ≈ 3 × 108 K would give the possibility of a sharp break.A recent upper limit on the line source strength of 100-MeV photons in the galactic plane may create some difficulties for cosmic-ray theory. The spectral shape of π-γ photons has become a matter of theoretical dispute.

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.

scholarly journals Survey of OH Masers at 1665 MHz. II. Galactic Longitude 340o to the Galactic Centre

1983 ◽  
Vol 36 (3) ◽  
pp. 361 ◽  
Author(s):  
JL Caswell ◽  
RF Haynes
Keyword(s):  
Ground State ◽  
Galactic Plane ◽  
Line Emission ◽  
State Transitions ◽  
Galactic Centre ◽  
Emission Sources ◽  
Type I ◽  
Type Ii ◽  
Formation Type ◽  
Galactic Longitude

The galactic plane from longitude 340� through the galactic centre to longitude + 2� has been searched for OH on the 1665 MHz transition. Forty-nine OH maser emission sources were detected and these have now been studied on all four OH ground-state transitions. Most of the masers are associated with regions of star formation (type I) while three may be examples of late-type stars (type II OH/IR) with unusually strong main-line emission

scholarly journals Diffusion of cosmic-ray electrons in the Galactic centre molecular cloud G0.13–0.13

2013 ◽  
Vol 9 (S303) ◽  
pp. 434-438
Author(s):  
Andrew Lehmann ◽  
Mark Wardle
Keyword(s):  
Molecular Cloud ◽  
Galactic Center ◽  
Galactic Disk ◽  
Line Emission ◽  
Cosmic Ray ◽  
Diffusion Models ◽  
Low Energy ◽  
Shell Morphology ◽  
Galactic Centre ◽  
Heating Rates

AbstractThe Galactic center (GC) molecular cloud G0.13–0.13 exhibits a shell morphology in CS J = (1 − 0), with ∼ 105 solar masses and expansion speed ∼ 20 km s−1, yielding a total kinetic energy ∼ 1051 erg. Its morphology is also suggestive of an interaction with the nonthermal filaments of the GC arc. 74 MHz emission indicates the presence of a substantial population of low energy electrons permeating the cloud, which could either be produced by the interaction with the arc or accelerated in the shock waves responsible for the cloud's expansion. These scenarios are explored using time dependent diffusion models.With these diffusion models, we determine the penetration of low-energy cosmic-ray electrons accelerated into G0.13–0.13 and calculate the spatial distribution of the cosmic-ray ionization and heating rates. We show that the 6.4 keV Fe Kα line emission associated with the electron population provides an observational diagnostic to distinguish these two acceleration scenarios.We discuss the implications of our results for understanding the distinct character of clouds in the central molecular zone compared to clouds in the Galactic disk, and how GC nonthermal filaments interact with molecular clouds.

Investigation of exotic states of 13C at low energy

2018 ◽  
Vol 27 (03) ◽  
pp. 1850025 ◽  
Author(s):  
N. Burtebayev ◽  
D. M. Janseitov ◽  
Zh. Kerimkulov ◽  
Y. S. Mukhamejanov ◽  
M. Nassurlla ◽  
...  
Keyword(s):  
Excited States ◽  
Cross Sections ◽  
Differential Cross ◽  
Ground State ◽  
Low Energy ◽  
Neutron Halo ◽  
Differential Cross Sections ◽  
Hoyle State ◽  
Exotic States ◽  
Diffraction Model

The differential cross-sections of the elastic and inelastic [Formula: see text]C scattering have been measured at E[Formula: see text][Formula: see text]MeV. The radii of the exited states: 3.09 [Formula: see text] and 8.86 [Formula: see text] MeV were determined using the Modified Diffraction Model. The radii of these excited states are larger than that of the ground state of [Formula: see text]C, confirming the suggestion that the 8.86 [Formula: see text] MeV state could be an analog of the Hoyle state in [Formula: see text]C and the 3.09 [Formula: see text] MeV state has a neutron halo. The possibility of coexistence of various exotic states in the structure of the [Formula: see text]C nucleus is shown.

scholarly journals Low Z Elements of High Grade Metamorphic Rocks by PIXE Analysis – A Comprehensive Review

2020 ◽  
Author(s):  
Avupati Venkata Surya Satyanarayana ◽  
Mokka Jagannadha Rao ◽  
Byreddy Seetharami Reddy
Keyword(s):  
Cross Section ◽  
Analytical Techniques ◽  
Thick Target ◽  
Light Energy ◽  
Low Energy ◽  
High Grade ◽  
X Rays ◽  
Pixe Analysis ◽  
X Ray ◽  
Line Intensities

Abstract. The majority of PIXE analytical study on geosciences has used 3 MeV proton beams for excitation and these studies generally uses the K-X-rays for low Z elements and L-X-rays for high Z elements. The present study of resulting spectra of metamorphic high grade rocks like charnockite can require striping techniques to resolve interference problems between low and high Z elements on the applications of light energy-PIXE using Si (Li) detector. In all forms of X-ray analysis, including thick-target light energy-PIXE, the X-ray signal is a dependent of the ionization cross section and for low-energy protons, the cross section is high for the K shells of light elements and the L shells of heavy elements in charnockite rock providing sufficient fluorescent yield for analytical purposes. For Z > 55, 3 MeV protons cannot ionize K-shell electrons and analysis depends on the use of L-X-ray lines in charnockite rock. Such L-X-ray spectra are complicated and can be affected by interferences K-X-rays from low Z elements. The low Z elements present in the charnockite were identified by previous complementary analytical techniques, but not identified in this study due to the above PIXE experiment limitations, and also particularly due to the dimensions of Si (Li) detector because of low energy K-X-rays of the elements absorbed by the detector window. Both interferences complexity and detector efficiency can lead to difficulties and ambiguity in the interpretation of spectra of low Z charnockite composition, a problem that is exacerbated by uncertainty in relative K-X-ray line intensities of low Z elements. From this investigation, the light energy-PIXE is ideal for the analysis of low Z 

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