PHOTONEUTRON EMISSION FROM Th232, U233, U238, AND Pu239

1957 ◽  
Vol 35 (4) ◽  
pp. 470-476 ◽  
Author(s):  
L. Katz ◽  
K. G. McNeill ◽  
M. LeBlanc ◽  
F. Brown
Keyword(s):  
Cross Section ◽  
Spontaneous Fission ◽  
Heavy Elements ◽  
X Rays ◽  
Yield Curves ◽  
X Ray ◽  
Low X

Measurements have been made of the numbers of neutrons emitted by the fissile materials Th232, U233, U238, and Pu239 under irradiation by betatron X-rays of various energies up to 23 Mev. Yield curves and corresponding cross section curves are given for these nuclides. At low X-ray energies it is found that the yield curves differ from those found with non-fissile heavy elements, corresponding to the fact that even at zero X-ray energy the fissile materials suffer (spontaneous) fission.

Studies of metaphase chromosomes in the scanning transmission x-ray microscope: Image fidelity, radiation damage and specimen preparation

1992 ◽  
Vol 50 (2) ◽  
pp. 1038-1039
Author(s):  
Shawn Williams ◽  
Xiaodong Zhang ◽  
Susan Lamm ◽  
Jack Van’t Hof
Keyword(s):  
Visible Light ◽  
Radiation Damage ◽  
Cross Section ◽  
Imaging Techniques ◽  
Dose Range ◽  
Specimen Preparation ◽  
X Rays ◽  
Metaphase Chromosomes ◽  
X Ray ◽  
Scanning Transmission

The Scanning Transmission X-ray Microscope (STXM) is well suited for investigating metaphase chromosome structure. The absorption cross-section of soft x-rays having energies between the carbon and oxygen K edges (284 - 531 eV) is 6 - 9.5 times greater for organic specimens than for water, which permits one to examine unstained, wet biological specimens with resolution superior to that attainable using visible light. The attenuation length of the x-rays is suitable for imaging micron thick specimens without sectioning. This large difference in cross-section yields good specimen contrast, so that fewer soft x-rays than electrons are required to image wet biological specimens at a given resolution. But most imaging techniques delivering better resolution than visible light produce radiation damage. Soft x-rays are known to be very effective in damaging biological specimens. The STXM is constructed to minimize specimen dose, but it is important to measure the actual damage induced as a function of dose in order to determine the dose range within which radiation damage does not compromise image quality.

scholarly journals Anisotropy of X-ray Absorption Cross Section in CeCoGe3 Single Crystal

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 544
Author(s):  
Andrei Rogalev ◽  
Fabrice Wilhelm ◽  
Elena Ovchinnikova ◽  
Aydar Enikeev ◽  
Roman Bakonin ◽  
...  
Keyword(s):  
Cross Section ◽  
Absorption Cross Section ◽  
Linear Dichroism ◽  
X Rays ◽  
Absorption Cross ◽  
X Ray ◽  
Measured Absorption ◽  
Linearly Polarized ◽  
X Ray Absorption ◽  
Absorption Edges

Absorption spectra of two orthogonal linearly polarized x-rays in a single CeCoGe3 crystal were measured at the ID12 beamline of the ESRF for the energies near the K-edges of Ge, Co and near the L23 edges of Ce. The X-ray natural linear dichroism (XNLD) was revealed in the vicinity of all the absorption edges, which indicates a splitting of electronic states in a crystalline field. Mathematical modelling in comparison with experimental data allowed the isotropic and anisotropic parts of atomic absorption cross section in CeCoGe3 to be determined near all measured absorption edges. The calculations also show that the “average” anisotropy of the cross section close to the Ge K-edge revealed in the experiment is less than the partial anisotropic contributions corresponding to Ge atoms in two different Wyckoff positions.

scholarly journals X-ray spectra and light curves of cooling novae and a nova like

2020 ◽  
Vol 499 (2) ◽  
pp. 3006-3018
Author(s):  
Bangzheng Sun ◽  
Marina Orio ◽  
Andrej Dobrotka ◽  
Gerardo Juan Manuel Luna ◽  
Sergey Shugarov ◽  
...  
Keyword(s):  
Light Curve ◽  
Accretion Rate ◽  
High Energy ◽  
Gravitational Energy ◽  
Light Curves ◽  
Clear Correlation ◽  
X Rays ◽  
High State ◽  
X Ray ◽  
Low X

ABSTRACT We present X-ray observations of novae V2491 Cyg and KT Eri about 9 yr post-outburst of the dwarf nova and post-nova candidate EY Cyg, and of a VY Scl variable. The first three objects were observed with XMM–Newton, KT Eri also with the Chandra ACIS-S camera, V794 Aql with the Chandra ACIS-S camera and High Energy Transmission Gratings. The two recent novae, similar in outburst amplitude and light curve, appear very different at quiescence. Assuming half of the gravitational energy is irradiated in X-rays, V2491 Cyg is accreting at $\dot{m}=1.4\times 10^{-9}{\!-\!}10^{-8}\,{\rm M}_\odot \,{\rm yr}^{-1}$, while for KT Eri, $\dot{m}\lt 2\times 10^{-10}{\rm M}_\odot \,{\rm yr}$. V2491 Cyg shows signatures of a magnetized WD, specifically of an intermediate polar. A periodicity of  39 min, detected in outburst, was still measured and is likely due to WD rotation. EY Cyg is accreting at $\dot{m}\sim 1.8\times 10^{-11}{\rm M}_\odot \,{\rm yr}^{-1}$, one magnitude lower than KT Eri, consistently with its U Gem outburst behaviour and its quiescent UV flux. The X-rays are modulated with the orbital period, despite the system’s low inclination, probably due to the X-ray flux of the secondary. A period of  81 min is also detected, suggesting that it may also be an intermediate polar. V794 Aql had low X-ray luminosity during an optically high state, about the same level as in a recent optically low state. Thus, we find no clear correlation between optical and X-ray luminosity: the accretion rate seems unstable and variable. The very hard X-ray spectrum indicates a massive WD.

scholarly journals Hard X-Rays and Gamma-Rays from SN 1987A

1988 ◽  
Vol 108 ◽  
pp. 446-447 ◽  
Author(s):  
M. Itoh ◽  
S. Kumagai ◽  
T. Shigeyama ◽  
K. Nomoto ◽  
J. Nishimura
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Gamma Rays ◽  
Mass Fraction ◽  
Heavy Elements ◽  
X Rays ◽  
X Ray ◽  
Sn 1987A ◽  
Mass Fractions ◽  
Theoretical Predictions

Gamma-rays originating from radioactive decays of 56Ni and 56Co and hard X-rays due to Compton degradation of γ-rays have been predicted to emerge when the supernova becomes sufficiently thin. The X-ray detections by Ginga (Dotani et al. 1988) and Kvant (Sunyaev et al. 1988) and more recent report of γ-ray detections by SMM (Matz et al. 1988) were much earlier than the theoretical predictions. (See Itoh et al. 1987 and references therein.)These observations would give important constraints on the distribution of the heavy elements and 56Co in the ejecta. We adopted the hydrodynamical model 11E1Y6 (Nomoto et al. 1988) and carried out Monte Carlo simulation for photon transfer. A step-like distribution of 56Co was assumed where the mass fraction of 56Co in the layers at Mr ≤ 4.6 M⊙, 4.6 − 6 M⊙, 6 − 8 M⊙, and 8 − 10 M⊙ are XCo = 0.0128, 0.0035, 0.0021, and 0.0011, respectively. Other heavy elements were distributed with mass fractions in proportion to 56Co.

An Algorithm for the Description of White and Characteristic Tube Spectra (11 ≤ Z ≤ 83, 10keV ≤ Eo ≤ 50keV)

1991 ◽  
Vol 35 (B) ◽  
pp. 721-726 ◽  
Author(s):  
H. Ebel ◽  
H. Wiederschwinger ◽  
J. Wernisch ◽  
P.A. Pella
Keyword(s):  
Kinetic Energy ◽  
Cross Section ◽  
Atomic Number ◽  
Solid Angle ◽  
Electron Interaction ◽  
X Rays ◽  
X Ray ◽  
The Cross ◽  
Spectral Responses ◽  
The Continuum

Kramers described the cross section of electron interaction with target atoms of atomic number Z bywhere Eo is the kinetic energy of impinging electrons, and E o S) the energy of x-ray photons of the continuum, Smith et al modified this equation, introducing an exponent x, so thatWe applied the cross-section σS, E to the evaluation of experimental results. The evaluation of the measured spectral responses of the x-ray signals nE was performed bywhere f(deff) describes the absorption of x-rays of energy E in the target, RE accounts for backscattering of electrons, DE quantifies the efficiency of x-ray detection within the solid angle Ω.

Energy Dispersive Techniques Using X-Ray Fluorescence with Primary X-Rays for Human Hard Tissues Analysis

2013 ◽  
Vol 583 ◽  
pp. 129-133
Author(s):  
Florin Miculescu ◽  
Ion Pencea ◽  
Marian Miculescu ◽  
Iulian Antoniac ◽  
Lucian Toma Ciocan ◽  
...  
Keyword(s):  
Biomedical Research ◽  
Life Quality ◽  
Heavy Elements ◽  
X Rays ◽  
X Ray ◽  
Energy Dispersion Spectrometry ◽  
Hard Tissues ◽  
Complementary Analysis ◽  
Systematic Collection

Among others, biomedical research is conducted for the systematic collection and analysis of data from which general conclusions can be drawn and which can increase the life quality of the patients. Given these issues, the aim of the research presented in this paper is to analyze the concentration of heavy elements from the human body, using complementary analysis methods, based on the energy dispersion spectrometry (EDS) technique.

PLATINUM GROUP ELEMENT HIGH-ENERGY PIXE

1990 ◽  
Vol 01 (02) ◽  
pp. 147-156 ◽  
Author(s):  
NORMAN M. HALDEN ◽  
FRANK C. HAWTHORNE ◽  
J.J. GUY DUROCHER ◽  
JASPER S.C. McKEE ◽  
ALI MIRZAI
Keyword(s):  
Quantitative Analysis ◽  
Proton Beam ◽  
Cross Section ◽  
Platinum Group Element ◽  
High Energy ◽  
Group Element ◽  
X Rays ◽  
Proton Bombardment ◽  
X Ray ◽  
Platinum Group

K X-ray spectra have been obtained from Platinum-Group Element (PGE) minerals using 40 MeV Proton-Induced X-ray Emission. It is possible to resolve all four component X-ray lines for the PGEs. In cases where there is more than one PGE present, some K X-ray lines may overlap, but in all cases, there were single lines available for quantitative analysis. The spectrum obtained from the sperrylite during exposure to the proton beam beam contained Au X-rays. The presence of the Au can be attributed to (p,xn) reactions with Pt, induced by proton bombardment of the sample. The intensity of Au X-ray lines in the spectrum is proportional to the amount of Pt in the sample and the cross-section for (p,xn) reactions between Pt and Au at 40 MeV.

Thermal Stresses in Passivated Copper Interconnects Determined by X-Ray Analysis and Finite Element Modeling

1994 ◽  
Vol 338 ◽  
Author(s):  
R.P. Vinci ◽  
E.M. Zielinski ◽  
J.C. Bravman
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Thermal Stresses ◽  
Hydrostatic Stress ◽  
Fiber Texture ◽  
Copper Interconnects ◽  
Mechanical Anisotropy ◽  
X Rays ◽  
X Ray ◽  
Lift Off

ABSTRACTStresses in passivated copper lines were determined from strains measured using x-ray methods and compared to stresses calculated using finite element methods. Copper lines, 2 µm wide by 0.8 µm thick, were fabricated by DC magnetron sputtering and lift off patterning. The cross section of these lines was trapezoidal, with approximately 50° sidewalls. One set of samples was left bare, the others passivated with Si3N4 in several different thicknesses. Strain was determined using x-rays. Stress was calculated using elastic moduli adjusted for predominantly (111) fiber texture. Elastic-plastic finite element models provided comparisons of the effects of passivation thickness, rectangular and trapezoidal cross section, and mechanical anisotropy due to preferred texture on the hydrostatic stress in a line. A similar model for aluminum also provided a comparison case of stress as a function of passivation thickness.

scholarly journals X-ray photolysis of CH3COCH3 ice: implications for the radiation effects of compact objects towards astrophysical ices

2020 ◽  
Vol 498 (1) ◽  
pp. 689-701 ◽  
Author(s):  
G A Carvalho ◽  
S Pilling
Keyword(s):  
Cross Section ◽  
Time Scales ◽  
Chemical Equilibrium ◽  
Radiation Effects ◽  
Broad Band ◽  
Compact Objects ◽  
X Rays ◽  
Formation Cross Section ◽  
X Ray ◽  
Molecular Abundances

ABSTRACT In this study, we employed broad-band X-rays (6–2000 eV) to irradiate the frozen acetone CH3COCH3, at the temperature of 12 K, with different photon fluences up to 2.7 × 1018 photons cm−2. Here, we consider acetone as a representative complex organic molecule (COM) present on interstellar ice grains. The experiments were conduced at the Brazilian Synchrotron facility (LNLS/CNPEN) employing infrared spectroscopy (FTIR) to monitor chemical changes induced by radiation in the ice sample. We determined the effective destruction cross-section of the acetone molecule and the effective formation cross-section for daughter species. Chemical equilibrium, obtained for fluence 2 × 1018 photons cm−2, and molecular abundances at this stage were determined, which also includes the estimates for the abundance of unknown molecules, produced but not detected, in the ice. Time-scales for ices, at hypothetical snow line distances, to reach chemical equilibrium around several compact and main-sequence X-ray sources are given. We estimate time-scales of 18 d, 3.6 and 1.8 months, 1.4 × 109–6 × 1011 yr, 600 and 1.2 × 107 yr, and 107 yr, for the Sun at 5 au, for O/B stars at 5 au, for white dwarfs at 1 LY, for the Crab pulsar at 2.25 LY, for Vela pulsar at 2.25 LY, and for Sagittarius A* at 3 LY, respectively. This study improves our current understanding about radiation effects on the chemistry of frozen material, in particular, focusing for the first time, the effects of X-rays produced by compact objects in their eventual surrounding ices.

CONTINUUM X RAYS IN HIGHLY CHARGED ION-ATOM COLLISIONS

1996 ◽  
Vol 06 (03n04) ◽  
pp. 441-445
Author(s):  
K. KAWATSURA ◽  
T. HASEGAWA ◽  
N. TERAZAWA ◽  
S. ARAI ◽  
M. SATAKA ◽  
...  
Keyword(s):  
Energy Region ◽  
Heavy Ion ◽  
X Rays ◽  
X Ray ◽  
Radiative Processes ◽  
Gas Target ◽  
Electron Bremsstrahlung ◽  
Low X ◽  
Atom Collision ◽  
The Continuum

Continuous X rays produced by highly charged heavy ion-atom collisions have been studied experimentally. 2–5.5 MeV/u F, Si, S and Cl ions with zero or one electron were bombarded with a thin gas target of H 2 and He. Emitted X-ray spectra were measured by using a Si(Li) X-ray detector at 90°. The characteristic X rays and radiative electron capture X rays were observed clearly, which were superimposed on the continuum X rays. The continuum X rays can be well explained by two types of radiative processes: mainly quasi-free electron bremsstrahlung (QFEB), and partly atomic bremsstrahlung (AB). It should be noticed that QFEB is predominant at low X-ray energy region and AB at high X-ray energy region in highly charged heavy ion-atom collision process.

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