Angular Distribution Of X-rays Research Articles

Strong higher-order resonant contribution to Fe Kα x-ray line polarization in hot anisotropic plasmas

SynopsisWe report the first systematic measurement of x-ray angular distribution and polarization following dielectronic, trielectronic and quadroelectronic recombination into He-like through O-like iron and krypton ions. The experimental data revealed that the the degree of polarization of x rays is dominated by relativistic Breit interaction and hitherto neglected higher-order trielectronic and quadroelectronic recombination resonances.

SU-E-I-44: Some Preliminary Analysis of Angular Distribution of X-Ray Scattered On Soft Tissues

Purpose: The angular distribution of x-radiation scattered at small angles (up to 16 degrees) from several different animal soft tissue (skin, fat, muscle, retina, etc) were measured using standard equipment devoted to study of crystal structure which provides excellent geometry conditions of measurements. showed measurable differences for different tissues. In the simplest possible case when measured samples do not differ in structure (different concentration solutions) it can be seen that intensity of scattered radiation is decreasing function of the concentration and the peak of the maximum of scattering distribution depends on the concentration as well. Methods: An x-ray scattering profile usually consists of sharp diffraction peak; however some properties of the spatial profiles of scattered radiation as intensity, the peak position, height, area, FWHM, the ratio of peak heights, etc. Results: The data contained measurable differences for different tissues. In the simplest possible case when measured samples do not differ in structure (different concentration solutions) it can be seen that intensity of scattered radiation is decreasing function of the concentration and the peak of the maximum of scattering distribution depends on the concentration as well. Measurements of different samples in the very preliminary phase showed that simple biological material usedmore » in study showed slightly different scattering pattern, especially at higher angles (around 10degrees). Intensity of radiation scattered from same tissue type is very dependent on water content and several more parameters. Conclusion: This preliminary study using animal soft tissues on the angular distributions of scattered x-rays suggests that angular distributions of X-rays scattered off of soft tissues might be useful in distinguishing healthy tissue from malignant soft tissue.« less

Instantaneous x-ray radiation energy from laser produced polystyrene plasmas for shock ignition conditions

Laser target energy coupling mechanism is crucial in the shock ignition (SI) scheme, and x-ray radiation energy is a non-negligible portion of the laser produced plasma energy. To evaluate the x-ray radiation energy amount at conditions relevant to SI scheme, instantaneous x-ray radiation energy is investigated experimentally with continuum phase plates smoothed lasers irradiating layer polystyrene targets. Comparative laser pulses without and with shock spike are employed. With the measured x-ray angular distribution, full space x-ray radiation energy and conversion efficiency are observed. Instantaneous scaling law of x-ray conversion efficiency is obtained as a function of laser intensity and time. It should be pointed out that the scaling law is available for any laser pulse shape and intensity, with which irradiates polystyrene planar target with intensity from 2 × 1014 to 1.8 × 1015 W/cm2. Numerical analysis of the laser energy transformation is performed, and the simulation results agree with the experimental data.

Structure and intermolecular interactions in selected binary solutions studied by X-ray methods

The results of X-ray structural studies of liquid chloroanisole C6H4OCH3Cl and 10% solutions of chloroanisole in 1,4-dimethylbenzene C8H10 are presented. It is the first paper on an X-ray diffraction study of the liquid solutions of chloroanisole. The X-ray measurements were made at 293K for the scattering angle range 2Θ varying from 6° to 120°. Averaged scattered X-ray angular distributions I¯(S) were determined. The angular distributions of the intensity of X-ray scattered by 10% solutions of chloroanisole in 1,4-dimethylbenzene were compared to the angular distributions obtained for liquid ortho-, meta- and para-chloroanisole. The differential radial distribution functions of electron density 4πr2∑j,knK¯j[ρk(r)−ρ0] were numerically found using the Fourier analysis from a modified Warren, Krutter and Morningstar equation. To the maxima of DRDFs, interatomic and intermolecular distances were assigned. The use of short-wave radiation from an X-ray tube with a molybdenum anode permitted determination of the spheres of intermolecular ordering in the studied liquids and their solutions. The experimental results were used to plot models of the most highly probable mutual disposition of the molecules in liquid chloroanisole and their solutions. The benzene rings of two molecules are situated in parallel plane what results in antiparallel setting of the dipole moments of the chloroanisole molecules. X-ray structural analysis was applied to determine the packing coefficients of chloroanisole molecules. The results obtained in this paper confirm the specific structural properties of the solutions studied.

Experimental study of X-ray emission properties of laser produced plasmas with Au and Au foam layer targets

Abstract The X-ray emission properties of Au plasmas consist of spectral distribution, M band fraction (2–4 keV), X-ray angular distribution and X-ray conversion efficiency, are imperative for various X-ray source applications. In order to investigate the X-ray emission properties of laser produced plasmas with Au and Au foam targets, experiments were carried out in Shenguang II laser facility. Au foam targets with densities of 0.6 and 0.4 g/cm3 were employed. The X-ray emission properties were measured. Excellent agreements of the experimental and theoretical spectral distributions and M band fractions were achieved.

Experimental Demonstration of the Breit Interaction which Dominates the Angular Distribution of X-ray Emission in Dielectronic Recombination

We report the experimentally determined angular distribution of the [1s2s(2)2p(1/2)](1)→[1s(2)2s(2)](0) transition in dielectronic recombination of Li-like Au. Recently, Fritzsche et al. [Phys. Rev. Lett. 103, 113001 (2009)] predicted that the Breit interaction plays a dominant role in the angular distribution of this transition. However, the predicted phenomenon has not yet been observed experimentally due to technical difficulties in conventional methods. To overcome the difficulties, we combine two different measurements with an electron beam ion trap (EBIT) to obtain the x-ray angular distribution. One is the x-ray measurement at 90° and another is the integral resonant strength measurement through the ion charge abundance in the EBIT. Our measurements agree well with the theoretical prediction and confirm the dominance of the Breit interaction.

Kossel lines in angular distribution of X-rays excited by protons in pyrolytic graphite quasi-crystal

Kossel line profiles were experimentally studied upon 1.5-MeV proton excitation of characteristic Kα radiation of argon atoms implanted into an UPV-1T graphite quasi-crystal. It was found that Kossel line profiles depend on argon ion implantation conditions, i.e., the lines generated in crystals implanted at temperatures of 150 and 200°C exhibit different widths and contrasts. In addition to the main Kossel cone line, a second cone line was detected caused by an additional texture component in the UPV-1T pyrolytic graphite quasi-crystal.

Angular Distribution of Fluorescent L X-Rays and Compton-Scattering Photons

ABSTRACT The angular distribution of fluorescent L X-rays and Compton-scattering photons was investigated by measuring differential cross sections for high–atomic-number elements. The measurements were taken simultaneously for L X-ray and Compton-scattering photons using Am-241 radioisotope as photon sources and a Si(Li) detector in various emission angles. The measurements confirm well-known angular dependency of the Compton-scattering differential cross section. L X-ray angular distribution measurements were carried out for the Ll, Lα, Lβ, and Lγ lines. It was observed from measured differential cross sections that Ll and Lα X-ray differential cross sections for the L3 substate depended on the emission angle, meaning that Ll and Lα X-rays had an anisotropic spatial distribution. On the other hand, the Lβ and Lγ X-rays do not show any significant anisotropy.

Angular Distribution of Argon Ions and X-Ray Emissions in the Apf Plasma Focus Device

Angular distribution of ion beam emission from an argon gas-filled plasma focus devices has been investigated using an array of five Faraday cups. The argon ion beam emission is found to be highly pressure-dependent and reaches its maximum at the pressure of 1 torr. The ions flux decreased as the working pressure increased; the maximum ion density at 1 torr was estimated to be around 9.24 × 1024 ions/steradian. Also, the study on the angular distribution of X-rays has been carried out using TLD-100 dosimeters. The intensity of ions reduced significantly at angles higher than ±11° but the X-ray distribution was bimodal, peaked approximately at ±15°.

Study of the Soft and Hard X-Ray Emitted by APF Plasma Focus Device in Different Pressures

In this paper, an investigation on the X-rays emitted in different pressures by APF plasma focus devices using filtered PIN-diodes and fast plastic scintillation detector is reported. The highest X-ray emission was observed in the pressure of 1.6 torr and the behavior of X-ray intensities registered by different filters versus applied pressure were seemed to be similar. The X-ray angular distribution was bimodal, peaked approximately at ±18°. The intensity of X-rays decreased abruptly along the central axis of the device where the cylindrical plasma pinch was formed.

NEW FEATURES OF DIFFRACTED CHANNELING RADIATION FROM ELECTRONS IN Si AND LiF CRYSTALS

It is shown that the band structure of transverse energy levels for (111) planar channeled electrons in the Si and LiF crystals qualitatively changes the angular distributions of X-rays emitted at the Bragg angles compared to calculations, which do not take into account this effect [5-7].

Angular anisotropy of the RCE X-rays under planar channeling as manifestation of geometric properties of the in-crystal electric field

Planar channeled ion under resonant coherent excitation conditions experiences an action of the oscillating electric field arising in the ion rest frame. We show how the alignment of the angular momentum of coherently excited ions and, hence, the angular anisotropy of their characteristic X-ray radiation are connected with the geometrical and symmetry properties of this field. The consideration is based on two examples of ( k , l ) = ( 2 , - 1 ) and (1, 3) resonances with 423 MeV/u Fe 24 + ions in ( 2 2 ¯ 0 ) planar channel of Si crystal, corresponding to different symmetries of the resonant field. In both cases the resonant electric field is elliptically polarized. A choice of an appropriate coordinate frame allows us to show the connection between the geometrical properties of the resonant field and the X-ray angular distributions especially clear. To illustrate, we calculate angular distributions of X-rays for individual ionic trajectories using density matrix formalism and then consider formation of the angular distributions not resolved by ion trajectory. Comparison with recent experimental data is done.

Angular distributions of diffracted X-ray radiation from channeled electrons in Si and LiF Crystals: Influence of energy levels band structure

It is shown that the band structure of the energy levels of planar channeled electrons qualitatively changes the angular distributions of X-rays emitted at Bragg angles.

OBSERVATION OF NONLINEAR THOMSON SCATTERING AT BNL-ATF

Measurement of X-rays produced in nonlinear Thomson scattering of high power laser and electron beams is a good test of electrodynamics in the high field region. We performed an experiment of head-on collision between sub-terawatt CO 2 laser and 60-MeV electron beams at Brookhaven National Laboratory, Accelerator Test Facility. Angular distributions of X-rays produced in Thomson scattering were measured and contribution of the second order nonlinear interaction was observed by comparing the distributions with Monte Carlo simulations based on the semi-classical theory of photon-electron interactions.

Angular Dependence of L X-ray Relative Intensities of Uranium and Thorium at 59.5 keV

INTRODUCTION The knowledge of relative intensities of K, L and higher shell X-rays is needed for the investigation of various phenomena in atomic physics. In earlier studies, L X-ray relative intensities and energies have been reported for many elements by several investigators [1–5], but the angular dependence of L X-ray relative intensity has not been reported. According to Flugge et a1 [6], if the angular momentum J=1/2 and J>1/2 of the originating shell, then the angular distribution of X-rays is isotropic and anisotropic, respectively. From this idea, Lα, Ll and some of Lβ, intensities are dependent on changing the scattering angles. In this study, we have measured the angular dependence of Lα, Lal, Lα/Lβ, and Lα/Lγ, intensity ratios of U and Th at different angles varying from 45° to 135°.

Highly asymmetric differential X-ray reflectometry of multilayer films

Bragg scattering of X-ray radiation in a highly asymmetric geometry from Langmuir-Blodgett films was investigated. A complex multi-peak structure was observed in the angular distribution of the scattered X-rays. The proposed simple explanation and the corresponding expressions for the peak positions are in good agreement with the experimental results. The same interpretation is successfully applied to experimental results for multilayer films of a quite different origin, the crystalline W/Si superstructures. Based on this agreement and the generalization of the results obtained we propose a new method of monitoring of angular distribution of X-rays propagating in the film at very small angles. Combined with the expressions obtained, it can be applied, in particular, to the determination of the critical angle of total external reflection from multilayer films which provides additional information compared with a conventional technique. Possibilities to study film imperfections are also outlined.

A model of an X-ray-illuminated accretion disk and corona

view Abstract Citations (98) References (50) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Model of an X-Ray--illuminated Accretion Disk and Corona Raymond, John C. Abstract The X-ray-illuminated surface of the accretion disk in a low-mass X-ray Binary (LMXRB) and the X-ray-heated corona above the disk produce optical, UV, and soft X-ray emission lines. This paper presents 1D models of the emission line spectra and the vertical temperature and density structures at different radii. The models include a detailed treatment of the important atomic processes and an escape probability treatment of radiative transfer. Soker and Raymond (1993) use the density structure predicted by these models for a 2D Monte Carlo simulation of the photon scattering in the accretion disk corona (ADC) to examine the effects of the ADC on the angular distribution of X-rays and the flux of X-rays incident on the outer disk. This paper concentrates on the emission line fluxes for various elemental abundances and disk parameters. The UV lines of the classic LMXRBs are consistent with the model predictions. Some CNO processing is necessary to account for the nitrogen and helium abundances in Sco X-1 and other LMXRBs. Comparison of the models with observed spectra also points to a soft X-ray component with luminosity comparable to the hard X-rays. The models predict a substantial luminosity in the group of highly ionized iron lines near 100 A. Publication: The Astrophysical Journal Pub Date: July 1993 DOI: 10.1086/172917 Bibcode: 1993ApJ...412..267R Keywords: Accretion Disks; Stellar Coronas; Stellar Models; X Ray Binaries; Abundance; Emission Spectra; Monte Carlo Method; Radiative Transfer; Stellar Luminosity; Stellar Temperature; Astrophysics; ACCRETION; ACCRETION DISKS; STARS: BINARIES: CLOSE; RADIATION MECHANISMS: MISCELLANEOUS; X-RAYS: STARS full text sources ADS | data products SIMBAD (5) MAST (1) INES (1)

Angular distribution and linear polarization of photons in dielectronic recombination of heliumlike ions

The angular distribution of X-rays in the dielectronic recombination of heliumlike ions is found to be, in general, nonisotropic with respect to the incident electron beam direction. Further, the X-rays are linearly polarized and the degree of polarization depends on the observation angle. Results are presented for the strong X-ray lines produced in the dielectronic recombination of heliumlike ions.

Anisotropy of x-rays and spin depencence of the photoabsorption of circularly polarized soft x-rays in magnetized Fe

Measurements were performed on the angular distribution of x-rays following internal conversion in the decay of191mIr oriented at low temperatures. The anisotropies of a series of L x-rays observed at 30° with respect to the orientation direction are in agreement with theoretical calculations. No anisotropy was observed for the K x-rays within the present experimental accuracy of 10−3. The high degree of circular polarization of the L and K x-rays was used to study the spin dependence of the photoabsorption in magnetized Fe.

High resolution K X-ray angular distribution measurements

The angular distribution of K X-rays produced by highly stripped fast ions is measured in high resolution with a rotatable Bragg plane-crystal spectrometer pivoted about a vertical axis through the target carbon foil. The helium-like and lithium-like spectra of 64 MeV sulfur ions are obtained at observation angles ranging from 20° to 160° using a NaCl crystal. The collected X-ray count is normalized to the incident beam flux, and the spectra are fit with Voigt functions. Due to the Doppler effect, the spectra are recorded at Bragg angles ranging from 57° to 72°. Thus, for absolute intensity measurements, the variation of crystal absorption and reflectivity with Bragg angle are significant. The theoretical curves for crystal reflectivity for both perfect and mosaic crystals, which have different angular dependences, can be generated for different X-ray polarizations, and compared with angular distribution data. The total beam X-ray intensities measured as a function of observation angle are corrected for relativistic effects and proportional counter efficiency dependences, and compared with the polarization-dependent theoretical curves to determine the optimum X-ray polarization value.