Plasma-Density Determination from X-Ray Radiography of Laser-Driven Spherical Implosions

AbstractOn the base of the 17 GHz radio maps of the Sun taken with the Nobeyama Radio Heliograph we estimate plasma parameters in the specific region of the sunspot atmosphere in the active region AR 11312. This region of the sunspot atmosphere is characterized by the depletion in coronal emission (soft X-ray and EUV lines) and the reduced absorption in the a chromospheric line (He I 1.083 μm). In the ordinary normal mode of 17 GHz emission the corresponding dark patch has the largest visibility near the central solar meridian. We infer that the reduced coronal plasma density of about ~ 5 × 10

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TH-A-217BCD-09: Volumetric Breast Density Determination Based On X-Ray Phase-Shifts

Medical Physics ◽

10.1118/1.4736280 ◽

2012 ◽

Vol 39 (6Part29) ◽

pp. 3990-3990

Author(s):

X Wu ◽

A Yan ◽

H Liu

Keyword(s):

Breast Density ◽

Phase Shifts ◽

X Ray ◽

Density Determination

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MHD simulation of solar flare by applying analytical energetic fast electron model

10.5194/egusphere-egu2020-4982 ◽

2020 ◽

Author(s):

Wenzhi Ruan ◽

Rony Keppens

Keyword(s):

Solar Flare ◽

Plasma Density ◽

Fast Electron ◽

Thermal Conduction ◽

Energetic Electron ◽

Simulation Code ◽

Electron Model ◽

Mhd Simulation ◽

Flare Loop ◽

X Ray

<p>In order to study the evaporation of chromospheric plasma and the formation of hard X-ray (HXR) sources in solar flare events, we coupled an analytic energetic electron model with the multi-dimensional MHD simulation code MPI-AMRVAC. The transport of fast electrons accelerated in the flare looptop is governed by the test particle beam approach reported in Emslie et al. (1978), now used along individual field lines. Anomalous resistivity, thermal conduction, radiative losses and gravity are included in the MHD model. The reconnection process self-consistently leads to formation of a flare loop system and the evaporation of chromospheric plasma is naturally recovered. The non-thermal HXR emission is synthesized from the local fast electron spectra and local plasma density, and thermal bremsstrahlung soft X-ray (SXR) emission is synthesized based on local plasma density and temperature. We found that thermal conduction is &#160;an efficient way to trigger evaporation flows.&#160;We also found that the generation of a looptop HXR source is a result of fast electron trapping, as evidenced by the pitch angle evolution. By comparing the SXR flux and HXR flux, we found that a possible reason for the &#8220;Neupert effect&#8221; is that the increase of non-thermal and thermal energy follows the same tendency.</p>

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Multipole electron densities and atomic displacement parameters in urea from accurate powder X-ray diffraction

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s205327331900799x ◽

2019 ◽

Vol 75 (4) ◽

pp. 600-609 ◽

Cited By ~ 2

Author(s):

Bjarke Svane ◽

Kasper Tolborg ◽

Lasse Rabøl Jørgensen ◽

Martin Roelsgaard ◽

Mads Ry Vogel Jørgensen ◽

...

Keyword(s):

Electron Density ◽

Molecular System ◽

Atomic Displacement ◽

High Symmetry ◽

X Ray Diffraction ◽

High Quality ◽

Acta Cryst ◽

X Ray ◽

Density Determination ◽

Structure Factors

Electron density determination based on structure factors obtained through powder X-ray diffraction has so far been limited to high-symmetry inorganic solids. This limit is challenged by determining high-quality structure factors for crystalline urea using a bespoke vacuum diffractometer with imaging plates. This allows the collection of data of sufficient quality to model the electron density of a molecular system using the multipole method. The structure factors, refined parameters as well as chemical bonding features are compared with results from the high-quality synchrotron single-crystal study by Birkedalet al.[Acta Cryst.(2004), A60, 371–381] demonstrating that powder X-ray diffraction potentially provides a viable alternative for electron density determination in simple molecular crystals where high-quality single crystals are not available.

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Simultaneous size and density determination of polymeric colloids by continuous contrast variation in small angle X-ray scattering

European Polymer Journal ◽

10.1016/j.eurpolymj.2016.01.012 ◽

2016 ◽

Vol 81 ◽

pp. 641-649 ◽

Cited By ~ 10

Author(s):

Raul Garcia-Diez ◽

Aneta Sikora ◽

Christian Gollwitzer ◽

Caterina Minelli ◽

Michael Krumrey

Keyword(s):

Small Angle ◽

Contrast Variation ◽

X Ray ◽

Density Determination ◽

X Ray Scattering ◽

Ray Scattering

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Pyrochlores. VII. The Oxides of Antimony: an X-Ray and Mössbauer Study

Canadian Journal of Chemistry ◽

10.1139/v72-106 ◽

1972 ◽

Vol 50 (5) ◽

pp. 690-700 ◽

Cited By ~ 70

Author(s):

David J. Stewart ◽

Osvald Knop ◽

Conrad Ayasse ◽

F. W. D. Woodhams

Keyword(s):

Type A ◽

Mössbauer Study ◽

Simultaneous Reduction ◽

X Ray ◽

Density Determination ◽

Pyrochlore Type ◽

Cubic Structure ◽

Antimonic Acid ◽

Mössbauer Parameters ◽

Defect Pyrochlore

Antimonic acid cannot be dehydrated by heating in air to give products of constant and reproducible weight without simultaneous reduction of some of the SbV to SbIII. Neither anhydrous Sb2O5 nor the hydroxy oxide Sb3O6OH postulated by Dihlström and Westgren can be obtained by this method. Two well-defined products of the dehydration/decomposition are Sb2O4.35(5) = Sb6O13, which forms between 650 and 850°, and β-Sb2O4. The latter, and not Sb2O3, results on heating Sb6O13 to 935°. Sb6O13 has a cubic structure of the defect pyrochlore type, a0 = 10.303(1) Å, x(O2) = 0.4304(14). Combined evidence from X-ray diffractometry, density determination, and Mössbauer spectroscopy leads to Sb3+Sb5+2O6O0.5 as the most probable structural formula.The Mössbauer parameters of β-Sb2O4 are closely similar to those reported for α-Sb2O4, but the isomer shifts (relative to InSb at 77°K) for SbV in antimonic acid and Sb6O13 are significantly larger than those in α- and β-Sb2O4.

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