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1

Analysis of x-ray spectrum obtained in electron cyclotron resonance x-ray source  

SciTech Connect

The analysis of the x-ray spectrum obtained in electron cyclotron resonance (ECR) x-ray source is carried out. Assuming single-particle motion, the electron acceleration and its final energy are calculated for TE{sub 111} cylindrical cavity field and uniform external dc magnetic field. In the calculation, initial coordinates of 40 000 electrons were uniformly selected over the central plane of the cavity using random number generator. The final energy of each electron when it hits the wall is stored and the electron energy distribution is obtained. Using the general purpose Monte Carlo N-particle transport code version 4A, the geometry of the ECR x-ray source is modeled. The x-ray energy spectrum is calculated for the geometry model and the numerically calculated electron energy distribution. The calculated x-ray spectrum is compared with the experimentally measured x-ray spectrum.

Baskaran, R.; Selvakumaran, T.S.; Sunil Sunny, C. [Radiological Safety Division, Safety Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India); Safety Research Institute, Kalpakkam 603 102, Tamil Nadu (India)

2006-03-15

2

X-Ray fluorescence analysis in the scanning electron microscope  

Microsoft Academic Search

Summary X-ray fluorescence analysis can be performed in a scanning electron microscope equipped with an energy dispersive X-ray spectrometer by means of a special attachment. For the production of primary X-rays a target is positioned in the electron beam. With this technique an improvement of the detection limits is obtained because of the small fraction of bremsstrahlung in the X-ray

P. Golob

1985-01-01

3

Betatron oscillations of electrons accelerated in laser wakefields characterized by spectral x-ray analysis.  

PubMed

Relativistic electrons accelerated by laser wakefields can produce x-ray beams from their motion in plasma termed betatron oscillations. Detailed spectral characterization is presented in which the amplitude of the betatron oscillations r is studied by numerical analysis of electron and x-ray spectra measured simultaneously. We find that r reaches as low as 1 mum in agreement with previous studies of radiation based on coherence and far-field spatial profile. PMID:18643171

Albert, Félicie; Shah, Rahul; Phuoc, Kim Ta; Fitour, Romuald; Burgy, Fréderic; Rousseau, Jean-Philippe; Tafzi, Amar; Douillet, Denis; Lefrou, Thierry; Rousse, Antoine

2008-05-01

4

Atmospheric electron x-ray spectrometer  

NASA Technical Reports Server (NTRS)

The present invention comprises an apparatus for performing in-situ elemental analyses of surfaces. The invention comprises an atmospheric electron x-ray spectrometer with an electron column which generates, accelerates, and focuses electrons in a column which is isolated from ambient pressure by a:thin, electron transparent membrane. After passing through the membrane, the electrons impinge on the sample in atmosphere to generate characteristic x-rays. An x-ray detector, shaping amplifier, and multi-channel analyzer are used for x-ray detection and signal analysis. By comparing the resultant data to known x-ray spectral signatures, the elemental composition of the surface can be determined.

Feldman, Jason E. (Inventor); George, Thomas (Inventor); Wilcox, Jaroslava Z. (Inventor)

2002-01-01

5

A Monte Carlo program for quantitative electron-induced X-ray analysis of individual particles.  

PubMed

A versatile Monte Carlo program for quantitative particle analysis in electron probe X-ray microanalysis is presented. The program includes routines for simulating electron-solid interactions in microparticles lying on a flat surface and calculating the generated X-ray signal. Simulation of the whole X-ray spectrum as well as phi(z) curves is possible. The most important facility of the program is the reverse Monte Carlo quantification of the chemical composition of microparticles, including low-Z elements, such as C, N, O, and F. This quantification method is based on the combination of a single scattering Monte Carlo simulation and a robust successive approximation. An iteration procedure is employed; in each iteration step, the Monte Carlo simulation program calculates characteristic X-ray intensities, and a new set of concentration values for chemical elements in the particle is determined. When the simulated X-ray intensities converge to the measured ones, the input values of elemental concentrations used for the simulation are determined as chemical compositions of the particle. This quantification procedure was evaluated by investigating various types of standard particles, and good accuracy of the methodology was demonstrated. A methodology for heterogeneity assessment of single particles is also described. PMID:12622376

Ro, Chul-Un; Osán, János; Szalóki, Imre; de Hoog, Johan; Worobiec, Anna; Van Grieken, René

2003-02-15

6

Scanning electron microscope/energy dispersive x ray analysis of impact residues in LDEF tray clamps  

NASA Technical Reports Server (NTRS)

Detailed optical scanning of tray clamps is being conducted in the Facility for the Optical Inspection of Large Surfaces at JSC to locate and document impacts as small as 40 microns in diameter. Residues from selected impacts are then being characterized by Scanning Electron Microscopy/Energy Dispersive X-ray Analysis at CNES. Results from this analysis will be the initial step to classifying projectile residues into specific sources.

Bernhard, Ronald P.; Durin, Christian; Zolensky, Michael E.

1993-01-01

7

ELECTRON FLUX SPECTRAL IMAGING OF SOLAR FLARES THROUGH REGULARIZED ANALYSIS OF HARD X-RAY SOURCE VISIBILITIES  

E-print Network

ELECTRON FLUX SPECTRAL IMAGING OF SOLAR FLARES THROUGH REGULARIZED ANALYSIS OF HARD X-RAY SOURCE a new method for imaging spectroscopy analysis of hard X-ray emission during solar flares. The method the method to a solar flare observed on 2002 February 20 by the RHESSI instrument. The event is characterized

Piana, Michele

8

ELECTRON FLUX SPECTRAL IMAGING OF SOLAR FLARES THROUGH REGULARIZED ANALYSIS OF HARD X-RAY SOURCE VISIBILITIES  

E-print Network

ELECTRON FLUX SPECTRAL IMAGING OF SOLAR FLARES THROUGH REGULARIZED ANALYSIS OF HARD X-RAY SOURCE method for imaging spectroscopy analysis of hard X-ray emission during solar flares. The method avoids then yields images of the elec- tron flux that vary smoothly with energy. We apply the method to a solar flare

California at Berkeley, University of

9

Airborne particles in the Miyagi Museum of Art in Sendai, Japan, studied by electron probe X-ray microanalysis and energy dispersive X-ray fluorescence analysis.  

PubMed

The presented work provides baseline data on the existing airborne conditions in the Miyagi Museum of Art in Sendai, Japan, during the summer of 2000. The chemical composition, size and indoor and outdoor origin of the suspended particulate matter were identified using a number of advanced X-ray techniques, such as Electron Probe X-Ray Microanalysis (EPXMA) and Energy Dispersive X-Ray Fluorescence Analysis (EDXRF). Our results, to the best of our knowledge, represent the first detailed study of the chemical nature of the indoor particulate matter in a Japanese museum and, as such, may contribute to future improvements of the air quality inside museums and to the lasting conservation of works of art. PMID:12036125

Injuk, Jasna; Osán, Janos; Van Grieken, René; Tsuji, Kouichi

2002-05-01

10

X-Ray Chemical Analysis of Multilayered Thin Films by Scanning Electron Microscopy and Total-Reflection-Angle X-Ray Spectroscopy  

NASA Astrophysics Data System (ADS)

Scanning electron microscopy and total-reflection-angle X-ray spectroscopy (SEM-TRAXS) have been applied to X-ray chemical analysis of multilayered thin films on Si substrates. Clear differences were observed in the take-off angle (? t) dependence of the X-ray intensities between Pd(10 nm)/Au(10 nm)/Si and Au(10 nm)/Pd(10 nm)/Si structures. The ? t dependence varied with layer thickness increase from 10 to 13 nm. An AlN(30 nm)/Al2O3(30 nm)/Si structure was also successfully analyzed by measuring the ? t dependence of NK ?, OK ?, AlK ? and SiK ? lines.

Yonemitsu, Kyoko; Shibata, Noriyoshi

1994-06-01

11

12.141 Electron Microprobe Analysis by Wavelength Dispersive X-ray Spectrometry, January (IAP) 2006  

E-print Network

Introduction to the theory of x-ray microanalysis through the electron microprobe including ZAF matrix corrections. Techniques to be discussed are wavelength and energy dispersive spectrometry, scanning backscattered ...

Chatterjee, Nilanjan

12

12.141 Electron Microprobe Analysis by Wavelength Dispersive X-ray Spectrometry, January IAP 2010  

E-print Network

This lab-oriented course introduces the student to the subject of X-ray spectrometry and micro-scale chemical quantitative analysis of solid samples through an intensive series of hands-on laboratory exercises that use the ...

Chatterjee, Nilanjan

2010-01-01

13

Comparison of synchrotron x-ray microanalysis with electron and proton microscopy for individual particle analysis  

SciTech Connect

This paper is concerned with the evaluation of the use of synchrotron/radiation induced x-ray fluorescences ({mu}-SRXRF) as implemented at two existing X-ray microprobes for the analysis of individual particles. As representative environmental particulates, National Institutes of Science and Technology (NIST) K227, K309, K441 and K961 glass microspheres were analyzed using two types of X-ray micro probes: the white light microprobe at beamline X26A of the monochromatic (15 keV) X-ray microprobe at station 7.6 of the SRS. For reference, the particles were also analyzed with microanalytical techniques more commonly employed for individual particles analysis such as EPMA and micro-PIXE.

Janssens, K.H.; van Langevelde, F.; Adams, F.C. [Universitaire Instelling Antwerpen, Antwerp (Belgium); Vis, R.D. [Vrije Univ., Amsterdam (Netherlands); Sutton, S.R.; Rivers, M.L. [Chicago Univ., IL (United States); Jones, K.W. [Brookhaven National Lab., Upton, NY (United States); Bowen, D.K. [Warwick Univ., Coventry (United Kingdom)

1991-12-31

14

Comparison of synchrotron x-ray microanalysis with electron and proton microscopy for individual particle analysis  

SciTech Connect

This paper is concerned with the evaluation of the use of synchrotron/radiation induced x-ray fluorescences ({mu}-SRXRF) as implemented at two existing X-ray microprobes for the analysis of individual particles. As representative environmental particulates, National Institutes of Science and Technology (NIST) K227, K309, K441 and K961 glass microspheres were analyzed using two types of X-ray micro probes: the white light microprobe at beamline X26A of the monochromatic (15 keV) X-ray microprobe at station 7.6 of the SRS. For reference, the particles were also analyzed with microanalytical techniques more commonly employed for individual particles analysis such as EPMA and micro-PIXE.

Janssens, K.H.; van Langevelde, F.; Adams, F.C. (Universitaire Instelling Antwerpen, Antwerp (Belgium)); Vis, R.D. (Vrije Univ., Amsterdam (Netherlands)); Sutton, S.R.; Rivers, M.L. (Chicago Univ., IL (United States)); Jones, K.W. (Brookhaven National Lab., Upton, NY (United States)); Bowen, D.K. (Warwick Univ., Coventry (United Kingdom))

1991-01-01

15

Total electron yield (TEY) a new approach for quantitative x-ray analysis  

SciTech Connect

An irradiation of solid samples with x-rays causes an electron emission from the sample surface, owing to photoabsorption. These electrons can be detected under vacuum conditions and are photo, Auger and secondary electrons. Due to inelastic collisions most of these electrons have lost some of their original kinetic energy along the path from the atom of origin to the surface. With nondispersive electron detection the total electron yield (TEY) is observed. For measurements performed with a tunable x-ray monochromator information on the qualitative composition can be obtained by the following procedure. The photon energy has to be tuned from below to above of one of the absorption edges of a given element. In case of its presence in the specimen an increase of the TEY-signal can be observed. 14 refs., 4 figs., 3 tabs.

Ebel, H.; Svagera, R.; Ebel, M.F.; Zagler, N. [Institut fuer Angewandte und Technische Physik, Vienna (Austria)

1995-12-31

16

Investigation of lithiated carbons by transmission electron microscopy and x-ray diffraction analysis  

SciTech Connect

The microstructures of lithiated synthetic graphite and carbon black were studied by high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) analysis. Information about the crystal structure of carbon containing various Li compositions can provide useful insights to our understanding of the Li storage mechanism in carbonaceous materials. Samples with compositions of Li{sub 0.93}C{sub 6} or Li{sub 0.45}C{sub 6} were found to contain both stage-one and stage-two compounds. These observations are consistent with XRD data. The changes in sample microstructure as the results of lithiation and exposure to electron irradiation were observed by TEM and recorded over several minutes in the microscope environment. Selected area electron diffraction patterns indicated that the lithiated samples quickly changed composition to LiC{sub 24}, which appeared to dominate during the brief analysis period. The layer planes in the lattice image of a disordered carbon black after Li insertion are poorly defined, and changes in the microstructure of these lithiated carbons was not readily apparent. Observations on these lithium intercalation compounds as well as the limitation of the experimental procedure will be presented.

Tran, T D; Song, X Y; Kinoshita, K

2000-10-26

17

Scanning electron microscope/energy dispersive x ray analysis of impact residues on LDEF tray clamps  

NASA Technical Reports Server (NTRS)

To better understand the nature of particulates in low-Earth orbit (LEO), and their effects on spacecraft hardware, we are analyzing residues found in impacts on the Long Duration Exposure Facility (LDEF) tray clamps. LDEF experiment trays were held in place by 6 to 8 chromic-anodized aluminum (6061-T6) clamps that were fastened to the spacecraft frame using three stainless steel hex bolts. Each clamp exposed an area of approximately 58 sq cm (4.8 cm x 12.7 cm x .45 cm, minus the bolt coverage). Some 337 out of 774 LDEF tray clamps were archived at JSC and are available through the Meteoroid & Debris Special Investigation Group (M&D SIG). Optical scanning of clamps, starting with Bay/Row A01 and working toward H25, is being conducted at JSC to locate and document impacts as small as 40 microns. These impacts are then inspected by Scanning Electron Microscopy/Energy Dispersive X-ray Analysis (SEM/EDXA) to select those features which contain appreciable impact residue material. Based upon the composition of projectile remnants, and using criteria developed at JSC, we have made a preliminary discrimination between micrometeoroid and space debris residue-containing impact features. Presently, 13 impacts containing significant amounts of unmelted and semi-melted micrometeoritic residues were forwarded to Centre National d'Etudes Spatiales (CNES) in France. At the CNES facilities, the upgraded impacts were analyzed using a JEOL T330A SEM equipped with a NORAN Instruments, Voyager X-ray Analyzer. All residues were quantitatively characterized by composition (including oxygen and carbon) to help understand interplanetary dust as possibly being derived from comets and asteroids.

Bernhard, Ronald P.; Durin, Christian; Zolensky, Michael E.

1992-01-01

18

Application of scanning electron microscopy to x-ray analysis of frozen- hydrated sections. I. Specimen handling techniques  

PubMed Central

X-ray microanalysis of frozen-hydrated tissue sections permits direct quantitative analysis of diffusible elements in defined cellular compartments. Because the sections are hydrated, elemental concentrations can be defined as wet-weight mass fractions. Use of these techniques should also permit determination of water fraction in cellular compartments. Reliable preparative techniques provide flat, smooth, 0.5 micrometers-thick sections with little elemental and morphological disruption. The specimen support and transfer system described permits hydrated sections to be transferred to the scanning electron microscope cold stage for examination and analysis without contamination or water loss and without introduction of extraneous x- ray radiation. PMID:7204491

1981-01-01

19

Scanning electron microscopic and X-ray micro analysis on tooth enamel exposed to alkaline agents.  

PubMed

The background of this study comprises two clinical cases, where patients exposed to aerosols of an alkaline and surface active cleaning agent developed loss of enamel substance on their teeth, further resulting in loss of teeth and partially destroyed soft tissues. The alkaline cleaning agent consisted of potassium hydroxide and various surfactants. The purpose of this study was to investigate possible changes in morphology and composition in human teeth enamel exposed to alkaline solutions, by means of X-ray micro analysis (XRMA), FTIR-spectroscopic analyses and scanning electron microscopy (SEM). Extracted premolars, exposed to potassium hydroxide solutions and alkaline cleaning solution,were analyzed by means of XRMA and SEM. Enamel powder, exposed to cleaning solution, was analyzed by means of FTIR. The SEM analysis revealed an increased porosity of the enamel surface and partially loss of enamel substance after exposure to alkaline solutions. The XRMA analyses revealed a decrease in carbon concentration while phosphorous and calcium showed no marked changes. The FTIR analyses showed no significant changes in peak heights or peak positions for phosphate, carbonate or hydroxide. It was concluded that human teeth enamel exposed to alkaline solutions showed loss of organic substance, marked pores in enamel surface and loss of substance in the enamel surface. PMID:21121412

Taubee, Fabian; Steiniger, Frank; Nietzsche, Sandor; Norén, Jörgen G

2010-01-01

20

SCANNING ELECTRON MICROSCOPY AND X-RAY DIFFRACTION ANALYSIS OF TANK 18 SAMPLES  

SciTech Connect

The F-Area Tank Farm (FTF) Performance Assessment (PA) utilizes waste speciation in the waste release model used in the FTF fate and transport modeling. The waste release modeling associated with the residual plutonium in Tank 18 has been identified as a primary contributor to the Tank 18 dose uncertainty. In order to reduce the uncertainty related to plutonium in Tank 18, a better understanding of the plutonium speciation in the Tank 18 waste (including the oxidation state and stoichiometry) is desired. Savannah River National Laboratory (SRNL) utilized Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) to analyze Tank 18 samples to provide information on the speciation of plutonium in the waste material. XRD analysis of the Tank 18 samples did not identify any plutonium mineral phases in the samples. These indicates the crystalline mineral phases of plutonium are below the detection limits of the XRD method or that the plutonium phase(s) lack long range order and are present as amorphous or microcrystalline solids. SEM analysis of the Tank 18 samples did locate particles containing plutonium. The plutonium was found as small particles, usually <1 {micro}m but ranging up to several micrometers in diameter, associated with particles of an iron matrix and at low concentration in other elemental matrices. This suggests the plutonium has an affinity for the iron matrix. Qualitatively, the particles of plutonium found in the SEM analysis do not appear to account for all of the plutonium in the sample based on concentrations determined from the chemical analysis of the Tank 18 samples. This suggests that plutonium is also distributed throughout the solids in low concentrations.

Hay, M.; O'Rourke, P.; Ajo, H.

2012-03-08

21

Comprehensive Study of Hydrated IDPs: X-Ray Diffraction, IR Spectroscopy and Electron Microscopic Analysis  

NASA Technical Reports Server (NTRS)

Chondritic hydrated interplanetary dust particles (IDPs) comprise up to 50% of all IDPs collected in the stratosphere(1). Although much is known about the mineralogy, chemistry and carbon abundance of hydrated IDPs (2-4) controversies still exist regarding their formation, history, and relationship to other primitive solar system materials. Hydrated IDPs are generally believed to be derived from asteroidal sources that have undergone some degree of aqueous alteration. However, the high C contents of hydrated IDPs (by 2 to 6X CI levels (3,4) indicate that they are probably not derived from the same parent bodies sampled by the known chondritic meteorites. We report the comprehensive study of individual hydrated IDPs. The strong depletion in Ca (I) has been used as a diagnostic feature of hydrated IDPs. The particles are embedded in elemental sulfur or low viscosity epoxy and ultramicrotomed thin sections are observed using a transmission electron microscope (TEM) equipped with an energy-dispersive X-ray detector (EDX) followed by other measurements including: 1) FTIR microspectroscopy to understand the significant constraints on the organic functionality and the nature of the C-bearing phases and 2) powder X-ray difiaction using a synchrotron X-ray source to understand the bulk mineralogy of the particles.

Nakamura, K.; Keller, L. P.; Nakamura, T.; Noguchi, T.; Nozaki, W.; Tomeoka, K.

2003-01-01

22

Champlane X-ray Analysis  

NASA Astrophysics Data System (ADS)

We summarize the X-ray analysis results of the Chandra Multiwavelength Plane survey (ChaMPlane), which is to constrain low luminosity accretion source content in the Galaxy using the Chandra archival data and optical and IR follow-up observations. From the Chandra archival data (A01-A06), we have detected more than 12000 point sources over 105 distinct fields (156 observations) covering 8 deg^2 in the Galactic Plane. The source catalog and X-ray results are available through our project website (http://hea-www.cfa.harvard.edu/ChaMPlane/). We highlight some of X-ray analysis findings and outline the future plan. For many X-ray sources with no reliable counterpart from optical or IR observations, X-ray driven source properties are the only hint to the nature of the sources. Therefore, we introduce a quantile-based technique to drive extinction and spectral parameters of each source, which allows to estimate the flux and distance of the source.

Hong, JaeSub; Grindlay, J.; van den Berg, M.; Laycock, S.; Koenig, X.; Zhao, P.; Schlegel, E.

2006-06-01

23

Stimulated Electronic X-Ray Raman Scattering  

NASA Astrophysics Data System (ADS)

We demonstrate strong stimulated inelastic x-ray scattering by resonantly exciting a dense gas target of neon with femtosecond, high-intensity x-ray pulses from an x-ray free-electron laser (XFEL). A small number of lower energy XFEL seed photons drive an avalanche of stimulated resonant inelastic x-ray scattering processes that amplify the Raman scattering signal by several orders of magnitude until it reaches saturation. Despite the large overall spectral width, the internal spiky structure of the XFEL spectrum determines the energy resolution of the scattering process in a statistical sense. This is demonstrated by observing a stochastic line shift of the inelastically scattered x-ray radiation. In conjunction with statistical methods, XFELs can be used for stimulated resonant inelastic x-ray scattering, with spectral resolution smaller than the natural width of the core-excited, intermediate state.

Weninger, Clemens; Purvis, Michael; Ryan, Duncan; London, Richard A.; Bozek, John D.; Bostedt, Christoph; Graf, Alexander; Brown, Gregory; Rocca, Jorge J.; Rohringer, Nina

2013-12-01

24

Synchrotron radiation induced x-ray micro analysis: A realistic alternative for electron- and ion beam microscopy?  

SciTech Connect

Synchrotron Radiation induced X-ray micro Fluorescence analysis ({mu}-SRXRF) is compared with more conventional microanalytical techniques such as Secondary Ion Microscopy (SIMS) and Electron Probe X-ray Microanalysis (EPXMA) for two typical microanalytical applications. SRXRF and EPXMA are employed for the analysis of individual particles, showing the complementary character of both techniques. By means of element mapping of trace constituents in a heterogeneous feldspar, the strong and weak points of SRXRF in comparison to EPXMA and SIMS are illustrated. The most striking difference between SRXRF and the other two microanalytical methods is the ability of SRXRF to probe deep into the investigated Material, whereas SIMS and EPXMA only investigate the upper surface of the material. The possibilities of SRXRF at third generation synchrotron rings is also briefly discussed.

Janssens, K.; Adams, F. [Universitaire Instelling Antwerpen, Antwerp (Belgium). Dept. of Chemistry; Rivers, M.L.; Jones, K.W. [Brookhaven National Lab., Upton, NY (United States)

1992-10-01

25

Synchrotron radiation induced x-ray micro analysis: A realistic alternative for electron- and ion beam microscopy  

SciTech Connect

Synchrotron Radiation induced X-ray micro Fluorescence analysis ([mu]-SRXRF) is compared with more conventional microanalytical techniques such as Secondary Ion Microscopy (SIMS) and Electron Probe X-ray Microanalysis (EPXMA) for two typical microanalytical applications. SRXRF and EPXMA are employed for the analysis of individual particles, showing the complementary character of both techniques. By means of element mapping of trace constituents in a heterogeneous feldspar, the strong and weak points of SRXRF in comparison to EPXMA and SIMS are illustrated. The most striking difference between SRXRF and the other two microanalytical methods is the ability of SRXRF to probe deep into the investigated Material, whereas SIMS and EPXMA only investigate the upper surface of the material. The possibilities of SRXRF at third generation synchrotron rings is also briefly discussed.

Janssens, K.; Adams, F. (Universitaire Instelling Antwerpen, Antwerp (Belgium). Dept. of Chemistry); Rivers, M.L.; Jones, K.W. (Brookhaven National Lab., Upton, NY (United States))

1992-01-01

26

Electron-ion-x-ray spectrometer system  

SciTech Connect

The authors describe a spectrometer system developed for electron, ion, and x-ray spectroscopy of gas-phase atoms and molecules following inner-shell excitation by tunable synchrotron radiation. The spectrometer has been used on beamline X-24A at the National Synchrotron Light Source for excitation-dependent studies of Ar L-shell and K-shell photoexcitation and vacancy decay processes. The instrumentation and experimental methods are discussed, and examples are given of electron spectra and coincidence spectra between electrons and fluorescent x-rays.

Southworth, S.H.; Deslattes, R.D. [National Inst. of Standards and Technology, Gaithersburg, MD (United States); MacDonald, M.A. [SERC, Warrington (United Kingdom). Daresbury Lab.; LeBrun, T. [Argonne National Lab., IL (United States)

1993-10-01

27

Degradation of spatial resolution in thin-foil x-ray microchemical analysis due to plural scattering of electrons  

SciTech Connect

A computer-based Monte Carlo simulation of incoherent plural scattering of electrons has been developed in order to estimate the broadening of an electron probe as it propagates through a solid. By applying this approach to modeling the spreading of a fine (50 A) probe focused on a thin foil in a scanning transmission electron microscope (STEM), we have estimated the spatial resolution of the compositional analysis obtainable using energy dispersive x-ray spectroscopy (EDS). Specifically, an attempt has been made to determine how the apparent microchemistry of a feature of finer dimensions than the broadened beam differs from the actual composition of the given feature. The apparent Ge concentration profile in the vicinity of a 200 A wide Ge platelet in a 5000 A thick Al foil was measured, using STEM and EDS, and compared with the profile predicted by Monte Carlo calculations. Results are presented and discussed.

Twigg, Mark Erickson

1982-01-01

28

Measurements and analysis of bremsstrahlung x-ray spectrum obtained in NANOGAN electron cyclotron resonance ion source  

SciTech Connect

From the ECR plasma, hot electrons leak across the magnetic lines of force and by striking the plasma chamber produce bremsstrahlung x-rays. The wall bremsstrahlung gives information on the confinement status of hot electron. In our studies, experimental measurements are carried out in NANOGAN electron cyclotron resonance (ECR) ion source for the wall bremsstrahlung x-rays and the results are presented. While optimizing a particular charge state in ECR ion source, experimental parameters are adjusted to get a maximum current. The wall bremsstrahlung components are studied in these cases for understanding the hot electron confinement conditions.

Baskaran, R.; Selvakumaran, T. S.; Rodrigues, G.; Kanjilal, D.; Roy, A. [Radiological Safety Division, Indira Gandhi Center for Atomic Research, Kalpakkam 603 102 (India); Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)

2008-02-15

29

Molecular and elemental characterisation of mineral particles by means of parallel micro-Raman spectrometry and Scanning Electron Microscopy\\/Energy Dispersive X-ray Analysis  

Microsoft Academic Search

The “fingerprinting” of a molecular structure obtained by micro-Raman spectroscopy (MRS) can be successfully complemented by means of X-ray spot analysis through the application of scanning electron microscopy equipped with an X-ray detector (SEM\\/EDX). The elemental composition revealed by SEM\\/EDX is essential for a correct interpretation of the collected Raman spectra. The results presented here illustrate how the two techniques

E. A. Stefaniak; A. Worobiec; S. Potgieter-Vermaak; A. Alsecz; S. Török; R. Van Grieken

2006-01-01

30

Quantitative analysis by X-ray induced total electron yield (TEY) compared to XRFA  

Microsoft Academic Search

The theoretical concepts of the two methods are similar. Consequently, comparable fundamental parameter algorithms can be developed and applied to quantitative analysis of bulk specimens and to investigation of thin layers by TEY and by XRFA. Whereas the sampling depth of XRFA is determined by photoelectric absorption, for TEY the escape probability of electrons reduces this quantity to values of

Horst Ebel

2004-01-01

31

Convergent x-ray monochromator for molecular microprobe analysis  

SciTech Connect

An improved apparatus and method are provided for electron spectroscopy for chemical analysis which permits analysis of micron sized regions of a heterogeneous sample surface. The apparatus includes a source of multidirectional X-ray radiation. A hollow cylindrical body receives the multidirectional X-ray radiation. The hollow cylindrical body includes a plurality of beam directing Johannsen-type diffracting crystals elements arrayed symmetrically and circumferentially around an axis of symmetry extending from the source of X-ray radiation to a surface of the sample. The array of Johannsen-type diffracting crystals transforms the multidirectional X-ray radiation into a hollow cone of monochromatic X-ray radiation that converges on a micron sized region on the sample surface. A screen opaque to X-rays is located along the axis of symmetry between the source of X-ray radiation and the sample. The screen prevents X-rays from the source from reaching the sample without being directed and diffracted by the beam directing and diffracting elements. An electron detector located along the axis of symmetry detects electrons emitted from the micron sized region of the sample surface. The electron detector is located between the X-ray screen and the sample surface. 4 figs.

Gamba, O.O.M.

1990-01-01

32

X-ray Free-electron Lasers  

SciTech Connect

In a free-electron laser (FEL) the lasing medium is a high-energy beam of electrons flying with relativistic speed through a periodic magnetic field. The interaction between the synchrotron radiation that is produced and the electrons in the beam induces a periodic bunching of the electrons, greatly increasing the intensity of radiation produced at a particular wavelength. Depending only on a phase match between the electron energy and the magnetic period, the wavelength of the FEL radiation can be continuously tuned within a wide spectral range. The FEL concept can be adapted to produce radiation wavelengths from millimeters to Angstroms, and can in principle produce hard x-ray beams with unprecedented peak brightness, exceeding that of the brightest synchrotron source by ten orders of magnitude or more. This paper focuses on short-wavelength FELs. It reviews the physics and characteristic properties of single-pass FELs, as well as current technical developments aiming for fully coherent x-ray radiation pulses with pulse durations in the 100 fs to 100 as range. First experimental results at wavelengths around 100 nm and examples of scientific applications planned on the new, emerging x-ray FEL facilities are presented.

Feldhaus, J.; /DESY; Arthur, J.; Hastings, J.B.; /SLAC

2007-02-23

33

X-ray- and electron induced infrared emission spectroscopy.  

SciTech Connect

We demonstrate the use of Fourier transform infrared (IR) spectroscopy for midinfrared emission measurements following x-ray or electron excitation. Spectra from an InAs low band-gap semiconductor film, which emits in the IR from 3000 to 3400 cm{sup -1}, are presented. There is good agreement between the present results and previously published laser-excited spectra. Using focused beams, it should be possible to perform sub-diffraction-limited IR imaging. In addition, simultaneous structural and electronic analysis could be performed using the x-ray or electron excitation probes.

Rosenberg, R. A.; Abu Haija, M.; Watkins, S. P. (X-Ray Science Division); (Simon Fraser Univ.)

2009-04-01

34

X-ray- and electron-induced infrared emission spectroscopy.  

PubMed

We demonstrate the use of Fourier transform infrared (IR) spectroscopy for midinfrared emission measurements following x-ray or electron excitation. Spectra from an InAs low band-gap semiconductor film, which emits in the IR from 3000 to 3400 cm(-1), are presented. There is good agreement between the present results and previously published laser-excited spectra. Using focused beams, it should be possible to perform sub-diffraction-limited IR imaging. In addition, simultaneous structural and electronic analysis could be performed using the x-ray or electron excitation probes. PMID:19405700

Rosenberg, R A; Abu Haija, M; Watkins, S P

2009-04-01

35

NASA Li/CF(x) cell problem analysis: Scanning electron microscopy with energy dispersive x ray spectrometry  

NASA Technical Reports Server (NTRS)

An analysis was made of Lithium/carbon fluoride cell parts for possible chloride contamination induced by exposure to thionyl chloride (SOCl2); various samples were submitted for analysis. Only a portion of the analysis which has been conducted is covered, herein, namely analysis by scanning electron microscopy with energy dispersive x ray spectrometry (SEM/EDS). A strip of nickel was exposed to SOCl2 vapors to observe variations in surface concentrations of sulfur and chlorine with time. By detecting chlorine one can not infer contamination by SOCl2 only that contamination is present. Six samples of stainless steel foil were analyzed for chlorine using EDS. Chlorine was not detected on background samples but was detected on the samples which had been handled including those which had been cleaned. Cell covers suspected of being contaminated while in storage and covers which were not exposed to the same storage conditions were analyzed for chlorine. Although no chlorine was found on the covers from cells, it was found on all stored covers. Results are presented with techniques shown for analysis and identification. Relevant photomicrographs are presented.

Baker, John

1991-01-01

36

Analysis of x-ray emission and electron dynamics in a capillary-guided laser wakefield accelerator  

NASA Astrophysics Data System (ADS)

The dynamics of electron acceleration driven by laser wakefield inside a 30.5 mm long dielectric capillary tube is analyzed using radiation emitted in the x-ray range. 3D particle-in-cell simulations, performed with parameters close to the experimental ones, show that in long plasmas, the accelerated electrons catch up and finally overrun the driving laser owing to a higher velocity of the electrons in the plasma. The electrons are then transversely scattered by the laser pulse, and penetrate the capillary wall where they generate bremsstrahlung radiation, modeled using geant4 simulations. The signature of bremsstrahlung radiation is detected using an x-ray camera, together with the betatron radiation emitted during electron acceleration in the plasma bubble. The reflection of betatron radiation from the inner capillary surface also accounts for a fraction of the observed signal on the x-ray camera. The simulation results are in agreement with the experimental ones and provide a detailed description of the electron and radiation properties, useful for the design of laser wakefield accelerators or radiation sources using long plasma media.

Ju, J.; Genoud, G.; Ferrari, H. E.; Dadoun, O.; Paradkar, B.; Svensson, K.; Wojda, F.; Burza, M.; Persson, A.; Lundh, O.; Andreev, N. E.; Wahlström, C.-G.; Cros, B.

2014-05-01

37

X-ray Free-electron Lasers  

SciTech Connect

We review the present status and properties of X-ray free-electron lasers in operation or under construction in the nanometer and sub-nanometer wavelength range, and the novel possibilities they offer for the study of atomic and molecular processes. We also discuss recent developments in relativistic electron beam physics that give us the possibility of designing a new generation of X-ray free-electron lasers that: a. are more compact; b. reduce the radiation pulse duration to one femtosecond or below; c. extend the photon energy to the 50 keV region. These results are obtained by reducing the electron bunch charge while at same time maximizing the beam brightness and reducing the bunch length to a value near or smaller than the free-electron laser cooperation length. In the last case the radiation pulse is fully coherent in the longitudinal and transverse space. The increase in beam brightness can also be used to reduce the beam energy needed for a given radiation wavelength, when, at the same time, the undulator period is reduced. The simultaneous decrease in beam energy and undulator period leads to a more compact free-electron laser, while the high beam brightness reduces the gain length and increases the coherent radiation intensity.

Pellegrini, Claudio [UCLA Department of Physics and Astronomy, Los Angeles, CA 90095-1547 (United States)

2009-09-10

38

STATISTICAL CONSIDERATIONS IN THE EMPLOYMENT OF SAX (SCANNING ELECTRON MICROSOPY WITH AUTOMATED IMAGE ANALYSIS AND X-RAY ENERGY SPECTROSCOPY) RESULTS FOR RECEPTOR MODELS  

EPA Science Inventory

Hundreds of thousands of individual particle measurements may be accumulated in a receptor model study employing Scanning electron microscopy with Automated image analysis and X-ray energy spectroscopy (SAX). At present, the summaries of these data are utilized in apportionment c...

39

Scanning electron microscopy and energy-dispersive x-ray spectroscopy analysis of submicrometer coal fly ash particles  

Microsoft Academic Search

Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX) were used to analyze two groups of submicrometer coal fly ash particles from eastern and western power plants. The composition of the particles was related to the composition of the regional coal used. No sulfur was detected in the ash from the plant using low-sulfur western coal. The power plant using

David Lichtman; Susan Mroczkowski

1985-01-01

40

Scanning electron microscopy, X-ray diffraction and thermal analysis study of the TiH{sub 2} foaming agent  

SciTech Connect

The decomposition of commercially available TiH{sub 2} was investigated while performing different thermal treatments. TiH{sub 2} powder, which is widely used as a foaming agent, was heat treated at 450 Degree-Sign C for various times, from 15 min to 120 min. Scanning electron microscopy (SEM) images of the surfaces at different magnifications were obtained and interpreted. A Bragg-Brentano X-ray diffractometer was used to measure the X-ray diffraction (XRD) spectra on all five samples. A close examination of the diffraction spectra showed that for an as-received sample and samples undergoing the longest thermal treatment (1 and 2 h) these spectra can be explained as deriving from cubic TiH{sub 1.924}, while for the other two samples they can be explained as deriving from tetragonal TiH{sub 1.924}. A constant-unit-cell-volume phase transition between the cubic and tetragonal phases in TiH{sub 2-y}-type compounds had been described in the literature. The unit-cell parameters obtained from measured spectra confirm that within the measurement uncertainty the unit-cell volume is indeed constant in all five samples. Thermo-gravimetry (TG) and differential thermal analysis (DTA) measurements were performed on all the samples, showing that the intensity of the dehydrogenation depends on the previous treatment of the TiH{sub 2}. After the thermal analysis XRD of the samples was performed again and the material was found to exhibit a Ti-like unit cell, but slightly enlarged due to the unreleased hydrogen. - Highlights: Black-Right-Pointing-Pointer TiH{sub 2} samples were cubic or tetragonal TiH{sub 1.924} Black-Right-Pointing-Pointer Onset of the hydrogen release temperature increases with the pre-treatment time. Black-Right-Pointing-Pointer Thermal dehydrogenation for the as-prepared TiH{sub 2} is a three-step process. Black-Right-Pointing-Pointer After thermal analysis 2 residual hydrogen TiH{sub x} phases, close to {alpha}Ti, appeared.

Mandrino, Djordje, E-mail: djordje.mandrino@imt.si [Institute of Metals and Technology, Lepi pot 11, 1000 Ljubljana (Slovenia)] [Institute of Metals and Technology, Lepi pot 11, 1000 Ljubljana (Slovenia); Paulin, Irena [Institute of Metals and Technology, Lepi pot 11, 1000 Ljubljana (Slovenia)] [Institute of Metals and Technology, Lepi pot 11, 1000 Ljubljana (Slovenia); Skapin, Sreco D. [Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia)] [Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia)

2012-10-15

41

VETA-I x ray test analysis  

NASA Technical Reports Server (NTRS)

This interim report presents some definitive results from our analysis of the VETA-I x-ray testing data. It also provides a description of the hardware and software used in the conduct of the VETA-I x-ray test program performed at the MSFC x-ray Calibration Facility (XRCF). These test results also serve to supply data and information to include in the TRW final report required by DPD 692, DR XC04. To provide an authoritative compendium of results, we have taken nine papers as published in the SPIE Symposium, 'Grazing Incidence X-ray/EUV Optics for Astronomy and Projection Lithography' and have reproduced them as the content of this report.

Brissenden, R. J. V.; Chartas, G.; Freeman, M. D.; Hughes, J. P.; Kellogg, E. M.; Podgorski, W. A.; Schwartz, D. A.; Zhao, P.

1992-01-01

42

Analysis of a Novel Diffractive Scanning Wire Beam Position Monitor (BPM) for Discriminative Profiling of Electron Vs. X Ray Beams  

SciTech Connect

Recent numerical studies of Free Electron Lasers (FELs) operating in the Self Amplified Spontaneous Emission (SASE) regime indicate a large sensitivity of the gain to the degree of transverse overlap (and associated phase coherence) between the electron and photon beams traveling down the insertion device. Simulations of actual systems imply that accurate detection and correction for this relative loss of overlap, rather than correction for the absolute departure of the electron beam from a fixed axis, is the preferred function of an FEL amplifier's Beam Position Monitor (BPM) and corrector systems. In this note we propose a novel diffractive BPM with the capability of simultaneously detecting and resolving the absolute (and relative) transverse positions and profiles of electron and x-ray beams co-propagating through an undulator. We derive the equations governing the performance of the BPM and examine its predicted performance for the SLAC Linac Coherent Light Source (LCLS), viz., for profiling multi-GeV electron bunches co-propagating with one-to-several-hundred keV x-ray beams. Selected research and development (r&d) tasks for fabricating and testing the proposed BPM are discussed.

Tatchyn, Roman; /SLAC

2011-09-01

43

Femtosecond x-ray absorption spectroscopy with hard x-ray free electron laser  

NASA Astrophysics Data System (ADS)

We have developed a method of dispersive x-ray absorption spectroscopy with a hard x-ray free electron laser (XFEL), generated by a self-amplified spontaneous emission (SASE) mechanism. A transmission grating was utilized for splitting SASE-XFEL light, which has a relatively large bandwidth (?E/E ˜ 5 × 10-3), into several branches. Two primary split beams were introduced into a dispersive spectrometer for measuring signal and reference spectra simultaneously. After normalization, we obtained a Zn K-edge absorption spectrum with a photon-energy range of 210 eV, which is in excellent agreement with that measured by a conventional wavelength-scanning method. From the analysis of the difference spectra, the noise ratio was evaluated to be ˜3 × 10-3, which is sufficiently small to trace minute changes in transient spectra induced by an ultrafast optical laser. This scheme enables us to perform single-shot, high-accuracy x-ray absorption spectroscopy with femtosecond time resolution.

Katayama, Tetsuo; Inubushi, Yuichi; Obara, Yuki; Sato, Takahiro; Togashi, Tadashi; Tono, Kensuke; Hatsui, Takaki; Kameshima, Takashi; Bhattacharya, Atanu; Ogi, Yoshihiro; Kurahashi, Naoya; Misawa, Kazuhiko; Suzuki, Toshinori; Yabashi, Makina

2013-09-01

44

Development and application of low energy X-ray and electron physics  

Microsoft Academic Search

Contents: X-ray spectrometry in the 100-1000 eV region; the characterization of X-ray photocathodes in The 0.1-10 keV photon energy region; description of a fixed, elliptical analyzer spectrograph for pulsed source analysis; low energy X-ray interaction coefficients: photoionization, scattering and reflection; first-page abstracts of selected examples of some research publications; and the low energy X-ray and electron spectrographic systems developed under

B. L. Henke

1981-01-01

45

Electron hopping interactions in amorphous ZnO films probed by x-ray absorption near edge structure analysis  

NASA Astrophysics Data System (ADS)

The x-ray absorption near edge structures of amorphous ZnO (a-ZnO) films were examined. The near-edge structure, which reflects the virtual electron hopping interactions in the photoabsorption final states, increased in intensity compared to crystalline ZnO. Theoretical path-by-path analyses revealed that this reflects the extinction of the multiple hopping processes found in paths such as Zn?O?O'?Zn or Zn?O?Zn'?Zn while the Zn-(O or Zn) hopping interactions remain. This suggests that the structural disorders in a-ZnO can induce the localization of the conduction band through the limited hopping interactions.

Cho, Deok-Yong; Kim, Jeong Hwan; Hwang, Cheol Seong

2011-05-01

46

Novel chemical analysis for thin films - Scanning electron microscopy and total-reflection-angle X-ray spectroscopy (SEM-TRAXS) - X-ray take-off angle effect  

NASA Astrophysics Data System (ADS)

Scanning electron microscopy and total-reflection-angle X-ray spectroscopy (SEM-TRAXS) was applied for fluorescence X-ray analysis of 50 A- and 125 A-thick Au thin films on Si(100). The intensity of the AuM line (2.15 keV) emitted from the Au thin films varied as a function of the take-off angle (theta sub t) with respect to the film surface; the intensity of AuM line from the 125 A-thick Au thin film was 1.5 times as large as that of SiK-alpha line (1.74 keV) emitted from the Si substrate when theta sub t is 0-3 deg, in the vicinity of a critical angle for total external reflection of the AuM line at Si (0.81 deg). In addition, the intensity of the AuM line emitted from the 50 A-thick Au thin film was also sufficiently strong for chemical analysis.

Usui, Toshio; Kamei, Masayuki; Aoki, Yuji; Morishita, Tadataka; Tanaka, Shoji

1991-09-01

47

Studies on x-ray and UV emissions in electron cyclotron resonance x-ray source  

SciTech Connect

A novel electron cyclotron resonance x-ray source is constructed based on the ECR technique. In this paper, the possibility of using the ECR x-ray source for producing UV rays by optimizing the plasma parameters is explored. X-ray and UV emissions from the ECR x-ray source are carried out for argon, nitrogen, and CO{sub 2} plasma. The x-ray spectral and dose measurements are carried with NaI(Tl) based spectrometer and dosimeter, respectively. For UV measurement, a quartz window arrangement is made at the exit port and the UV intensity is measured at 5 cm from the quartz plate using UV meter. The x-ray and UV emissions are carried out for different microwave power levels and gas pressures. The x-ray emission is observed in the pressure range {<=}10{sup -5} Torr, whereas the UV emission is found to be negligible for the gas pressures <10{sup -5} Torr and it starts increasing in the pressure range between 10{sup -5} and 10{sup -3} Torr. At high-pressure range, collision frequency of electron-atom is large which leads to the higher UV flux. At low pressure, the electron-atom collision frequency is low and hence the electrons reach high energy and by hitting the cavity wall produces higher x-ray flux. By choosing proper experimental conditions and plasma gas species, the same source can be used as either an x-ray source or an UV source.

Baskaran, R.; Selvakumaran, T. S. [Radiological Safety Division, Indira Gandhi Center for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India)

2008-02-15

48

Proton induced quasi-monochromatic x-ray beams for soft x-ray spectroscopy studies and selective x-ray fluorescence analysis  

SciTech Connect

We present the analytical features and performance of an x-ray spectroscopy end station of moderate energy resolution operating with proton-induced quasi-monochromatic x-ray beams. The apparatus was designed, installed and operated at the 5.5 MV Tandem VdG Accelerator Laboratory of the Institute of Nuclear Physics, N.C.S.R. 'Demokritos,' Athens. The setup includes a two-level ultrahigh vacuum chamber that hosts in the lower level up to six primary targets in a rotatable holder; there, the irradiation of pure element materials-used as primary targets-with few-MeV high current ({approx}{mu}A) proton beams produces intense quasi-monochromatic x-ray beams of selectable energy. In the chamber's upper level, a six-position rotatable sample holder hosts the targets considered for x-ray spectroscopy studies. The proton-induced x-ray beam, after proper collimation, is guided to the sample position whereas various filters can be also inserted along the beam's path to eliminate the backscattered protons or/and to absorb selectively components of the x-ray beam. The apparatus incorporates an ultrathin window Si(Li) spectrometer (FWHM 136 eV at 5.89 keV) coupled with low-noise electronics capable of efficiently detecting photons down to carbon K{alpha}. Exemplary soft x-ray spectroscopy studies and results of selective x-ray fluorescence analysis are presented.

Sokaras, D. [Institute of Nuclear Physics, N.C.S.R. Demokritos, Aghia Paraskevi, 15310 Athens (Greece); Zarkadas, Ch. [PANalytical B.V., 7600 AA Almelo (Netherlands); Fliegauf, R.; Beckhoff, B. [Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, 10587 Berlin (Germany); Karydas, A. G. [Institute of Nuclear Physics, N.C.S.R. Demokritos, Aghia Paraskevi, 15310 Athens (Greece); Nuclear Spectrometry and Applications Laboratory, IAEA Laboratories, A-2444 Seibersdorf (Austria)

2012-12-15

49

Analysis of 20 KEV Electron Induced X-Ray Production in Skull, Femur/tibia Bones of Rats  

NASA Astrophysics Data System (ADS)

Hind-limb suspension (HLS) of rats is a NASA validated model of simulated weightlessness. This study examines the effects of microgravity on the skeletal system of rats to assess whether or not exposure of rats to HLS for one week will induce alteration of structural features in selected bones. Four groups of rats were used: two unsuspended controls and two suspended groups. Body weight, food, and water intake were monitored daily before and after suspension. X-rays were measured by a liquid nitrogen cooled Si(li) detector on a Scanning Electron Microscope (SEM) that provided the 20 keV electron beam. X-ray data were collected from square cross sections between 100 ?m2 and 104 ?m2. The bones were measured for elemental levels of calcium, phosphorus, oxygen and carbon from both control and HLS rats. The average body weight of all HLS groups decreased compared to their respective unsuspended controls. Food and water intake was also lower in both suspended groups. A correlation among HLS and control samples in terms of the distribution of the primary elements was found in the bone tissue when analyzed as a function of position along the hind-leg and within the cross sections.

Mehta, Rahul; Watson, Alec; Ali, Nawab; Soulsby, Michael; Chowdhury, Parimal

2010-04-01

50

Opportunities for resonant elastic X-ray scattering at X-ray free-electron lasers  

NASA Astrophysics Data System (ADS)

X-ray Free-Electron Lasers (FELs) are beginning to deliver a revolution in X-ray experiments, thanks to their ultra-bright (peak brightness exceeding 1033 photons/s/mm2/mrad2/0.1%BW), ultrashort (down to a few fs), spatially coherent X-ray pulses. Presently operational facilities cover wide spectral ranges, from the VUV and soft X-ray wavelengths of FLASH in Hamburg (down to 4.2 nm), to the hard X-rays delivered by the LCLS in Stanford (wavelengths of 0.15 nm or shorter). The basic properties of the new sources are briefly reviewed, and the impact on resonant scattering experiments is discussed. The perspective of investigating ultrafast magnetism, and, more generally, the time-dependent response of strongly correlated electron systems, in a pump-and-probe mode at the L edges of 3d transition metals, would be very attractive. In the hard X-ray range, the very recent proposal of self-seeded X-ray FELs, with 10-5 intrinsic bandwidth, tunable wavelength, 100 fs pulses and number of photons per pulse of order 1012 also opens exciting possibilities for resonant scattering.

Altarelli, M.

2012-06-01

51

The Swift X-ray Telescope Cluster Survey. II. X-ray spectral analysis  

NASA Astrophysics Data System (ADS)

Aims: We present a spectral analysis of a new, flux-limited sample of 72 X-ray selected clusters of galaxies identified with the X-ray Telescope (XRT) on board the Swift satellite down to a flux limit of ~10-14 erg s-1 cm-2 (SWXCS). We carry out a detailed X-ray spectral analysis with the twofold aim of measuring redshifts and characterizing the properties of the intracluster medium (ICM) for the majority of the SWXCS sources. Methods: Optical counterparts and spectroscopic or photometric redshifts for some of the sources are obtained with a cross-correlation with the NASA/IPAC Extragalactic Database. Additional photometric redshifts are computed with a dedicated follow-up program with the Telescopio Nazionale Galileo and a cross-correlation with the SDSS. In addition, we also blindly search for the Hydrogen-like and He-like iron K? emission line complex in the X-ray spectrum. We detect the iron emission lines in 35% of the sample, and hence obtain a robust measure of the X-ray redshift zX with typical rms error 1-5%. We use zX whenever the optical redshift is not available. Finally, for all the sources with measured redshift, background-subtracted spectra are fitted with a single-temperature mekal model to measure global temperature, X-ray luminosity and iron abundance of the ICM. We perform extensive spectral simulations to accounts for fitting bias, and to assess the robustness of our results. We derive a criterion to select reliable best-fit models and an empirical formula to account for fitting bias. The bias-corrected values are then used to investigate the scaling properties of the X-ray observables. Results: Overall, we are able to characterize the ICM of 46 sources with redshifts (64% of the sample). The sample is mostly constituted by clusters with temperatures between 3 and 10 keV, plus 14 low-mass clusters and groups with temperatures below 3 keV. The redshift distribution peaks around z ~ 0.25 and extends up to z ~ 1, with 60% of the sample at 0.1 < z < 0.4. We derive the luminosity-temperature relation for these 46 sources, finding good agreement with previous studies. Conclusions: Thanks to the good X-ray spectral quality and the low background of Swift/XRT, we are able to measure ICM temperatures and X-ray luminosities for the 46 sources with redshifts. Once redshifts are available for the remaining 26 sources, this sample will constitute a well-characterized, flux-limited catalog of clusters distributed over a broad redshift range (0.1 ? z ? 1.0) providing a statistically complete view of the cluster population with a selection function that allows a proper treatment of any measurement bias. The quality of the SWXCS sample is comparable to other samples available in the literature and obtained with much larger X-ray telescopes. Our results have interesting implications for the design of future X-ray survey telescopes, characterized by good-quality PSF over the entire field of view and low background. Tables 1 and 2 and Appendix A are available in electronic form at http://www.aanda.orgCatalog and data products of SWXCS, constantly updated, are made available to the public through the websites http://www.arcetri.astro.it/SWXCS/ and http://swxcs.ustc.edu.cn/

Tozzi, P.; Moretti, A.; Tundo, E.; Liu, T.; Rosati, P.; Borgani, S.; Tagliaferri, G.; Campana, S.; Fugazza, D.; D'Avanzo, P.

2014-07-01

52

Fundamental physics with an X-ray free electron laser  

Microsoft Academic Search

Of late, laboratories around the world are considering building X-ray free electron lasers based on high energy electron accelerators\\u000a (with energies exceeding 10 GeV) to produce bright coherent X rays with wavelengths on the order of 1 . Because of the extremely\\u000a small wavelength and high brilliance of these coherent X rays, there is an unprecedented opportunity to explore new

T. Tajima

2003-01-01

53

Copyright The Discussion Group of X-Ray Analysis,  

E-print Network

changing X-ray intensity. Although these characteristics seem to be disadvantageous to measurement, it canCopyright © The Discussion Group of X-Ray Analysis, The Japan Society for Analytical Chemistry X X An X-Ray Source Powered by a Dry Battery and Its Application to X-Ray Fluorescence Analysis Hiroyuki

Jun, Kawai

54

MESSENGER X-Ray Spectrometer Detection of Electron-induced X-ray Fluorescence from Mercury's Surface  

NASA Astrophysics Data System (ADS)

X-ray emission from solar system bodies has been observed for decades. The surface of planets with no atmosphere may be excited by solar X-rays, solar wind particles (primarily electrons), and ions, producing line emission and bremsstrahlung. Measurement of solar-induced X-ray fluorescence (XRF) from planetary surfaces has been used to infer surface elemental abundances at the Moon and the asteroids 433 Eros and 25143 Itokawa. More recently, the MESSENGER X-Ray Spectrometer (XRS) has reported on Mercury's surface composition derived from measurements of solar-flare-induced XRF. The XRS began orbital observations on 23 March 2011 and has observed X-ray fluorescence from the surface of the planet during both "quiet-Sun" and flaring conditions whenever a sunlit portion of Mercury has been within the XRS field of view. XRS can detect the characteristic X-rays of Mg, Al, and Si during quiet-Sun conditions, but solar flares are required to produce measurable signals from the elements of higher atomic number such as S, Ca, Ti, and Fe. Nevertheless, X-ray fluorescence up to the Ca fluorescent line (3.69 keV) has been detected from Mercury's surface at times when the XRS field of view included only unlit portions of the planet or during quiet-Sun illumination. Many such events have been detected and are identified as electron-induced X-ray emission produced by ~1-10 keV electrons interacting with Mercury's surface. Electrons in this energy range were detected by the XRS during the three Mercury flybys, and since the beginning of orbital operations electrons of this same energy range have been detected by XRS during almost every orbit. These electron events last from minutes to tens of minutes. Electron transport models suggest that a large percentage of these quasi-trapped electrons do not complete even a single drift orbit about Mercury before impacting the surface. Knowledge of the precipitating electron distribution at the planet's surface makes it possible to infer surface composition from the measured fluorescent spectra. Elemental compositions for Mg, Al, S, Ca, Ti, and Fe have been derived from these measurements and are in line, to within expected uncertainties, with those inferred from solar-induced XRF. This agreement confirms the value of electron-induced X-ray emission measurements as a tool for geochemical analysis at Mercury.

Starr, R. D.; Schriver, D.; Nittler, L. R.; Weider, S. Z.; Byrne, P. K.; Ho, G. C.; Rhodes, E. A.; Schlemm, C. E.; Solomon, S. C.; Travnicek, P. M.

2012-12-01

55

Note: Alignment/focus dependent core-line sensitivity for quantitative chemical analysis in hard x-ray photoelectron spectroscopy using a hemispherical electron analyzer  

SciTech Connect

X-ray photoelectron spectroscopy is an established technique for quantitative chemical analysis requiring accurate peak intensity analysis. We present evidence of focus/alignment dependence of relative peak intensities for peaks over a broad kinetic energy range with a hemispherical electron analyzer operated in a position imaging mode. A decrease of over 50% in the Ag 2p{sub 3/2} to Ag 3d ratio is observed in a Ag specimen. No focus/alignment dependence is observed when using an angular imaging mode, necessitating the use of angular mode for quantitative chemical analysis.

Weiland, Conan; Browning, Raymond; Karlin, Barry A.; Fischer, Daniel A.; Woicik, Joseph C. [Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

2013-03-15

56

Density gradient free electron collisionally excited X-ray laser  

DOEpatents

An operational X-ray laser (30) is provided that amplifies 3p-3s transition X-ray radiation along an approximately linear path. The X-ray laser (30) is driven by a high power optical laser. The driving line focused optical laser beam (32) illuminates a free-standing thin foil (34) that may be associated with a substrate (36) for improved structural integrity. This illumination produces a generally cylindrically shaped plasma having an essentially uniform electron density and temperature, that exists over a long period of time, and provides the X-ray laser gain medium. The X-ray laser (30) may be driven by more than one optical laser beam (32, 44). The X-ray laser (30) has been successfully demonstrated to function in a series of experimental tests.

Campbell, Edward M. (Pleasanton, CA); Rosen, Mordecai D. (Berkeley, CA)

1989-01-01

57

Density gradient free electron collisionally excited x-ray laser  

DOEpatents

An operational x-ray laser is provided that amplifies 3p-3s transition x-ray radiation along an approximately linear path. The x-ray laser is driven by a high power optical laser. The driving line focused optical laser beam illuminates a free-standing thin foil that may be associated with a substrate for improved structural integrity. This illumination produces a generally cylindrically shaped plasma having an essentially uniform electron density and temperature, that exists over a long period of time, and provides the x-ray laser gain medium. The x-ray laser may be driven by more than one optical laser beam. The x-ray laser has been successfully demonstrated to function in a series of experimental tests.

Campbell, E.M.; Rosen, M.D.

1984-11-29

58

X-Ray-Diffraction Tests Of Irradiated Electronic Devices: II  

NASA Technical Reports Server (NTRS)

Report describes research on use of x-ray diffraction to measure stresses in metal conductors of complementary metal oxide/semiconductor (CMOS) integrated circuits exposed to ionizing radiation. Expanding upon report summarized in "X-Ray-Diffraction Tests Of Irradiated Electronic Devices: I" (NPO-18803), presenting data further suggesting relationship between electrical performances of circuits and stresses and strains in metal conductors.

Shaw, David C.; Lowry, Lynn E.; Barnes, Charles E.

1993-01-01

59

X-ray tube with magnetic electron steering  

DOEpatents

An X-ray tube uses a magnetic field to steer electrons. The magnetic field urges electrons toward the anode, increasing the proportion of electrons emitted from the cathode that reach desired portions of the anode and consequently contribute to X-ray production. The magnetic field also urges electrons reflected from the anode back to the anode, further increasing the efficiency of the tube.

Reed, Kim W. (Albuquerque, NM); Turman, Bobby N. (Albuquerque, NM); Kaye, Ronald J. (Albuquerque, NM); Schneider, Larry X. (Albuquerque, NM)

2000-01-01

60

X-ray and electron microscope studies on aluminium oxide trihydrates  

Microsoft Academic Search

Summary  Gels and sols of aluminum oxide trihydrate were prepared by five different methods and studied by x-ray diffraction and electron\\u000a microscopy. The x-ray diffraction analysis has shown that all methods produce mixtures of Gibbsite and Bayerite, the relative\\u000a proportions of each varying from method to method. A sol and gel prepared by the same method present identical x-ray diffraction\\u000a patterns

John H. L. Watson; Jonathan Parsons; A. Vallejo-Freire; P. Souza Santos

1955-01-01

61

Growth and texture of spark plasma sintered Al2O3 ceramics: A combined analysis of X-rays and electron back scatter diffraction  

NASA Astrophysics Data System (ADS)

Textured alumina ceramics were obtained by Spark Plasma Sintering of undoped commercial ?-Al2O3 powders. Various parameters (density, grain growth, grain size distribution) of the alumina ceramics, sintered at two typical temperatures 1400 °C and 1700 °C, are investigated. Quantitative textural and structural analysis, carried out using a combination of Electron Back Scattering Diffraction and X-ray diffraction, are represented in the form of mapping and pole figures. The mechanical properties of these textured alumina ceramics include high elastic modulus and hardness values with high anisotropic nature, opening the door for a large range of applications.

Pravarthana, D.; Chateigner, D.; Lutterotti, L.; Lacotte, M.; Marinel, S.; Dubos, P. A.; Hervas, I.; Hug, E.; Salvador, P. A.; Prellier, W.

2013-04-01

62

An ultra fast electron beam x-ray tomography scanner  

Microsoft Academic Search

This paper introduces the design of an ultra fast x-ray tomography scanner based on electron beam technology. The scanner has been developed for two-phase flow studies where frame rates of 1 kHz and higher are required. Its functional principle is similar to that of the electron beam x-ray CT scanners used in cardiac imaging. Thus, the scanner comprises an electron

F. Fischer; D. Hoppe; E. Schleicher; G. Mattausch; H. Flaske; R. Bartel; U. Hampel

2008-01-01

63

An ultra fast electron beam x-ray tomography scanner  

Microsoft Academic Search

This paper introduces the design of an ultra fast x-ray tomography scanner based on electron beam technology. The scanner has been developed for two-phase flow studies where frame rates of 1 kHz and higher are required. Its functional principle is similar to that of the electron beam x-ray CT scanners used in cardiac imaging. Thus, the scanner comprises an electron

64

Gunshot residue testing in suicides: Part I: Analysis by scanning electron microscopy with energy-dispersive X-ray.  

PubMed

Several different methods can be employed to test for gunshot residue (GSR) on a deceased person's hands, including scanning electron microscopy with energy-dispersive x-ray spectroscopy (SEM-EDX) and inductively coupled plasma-atomic emission spectrometry (ICP-AES). Each of these techniques has been extensively studied, especially on living individuals. The current studies (Part I and Part II) were designed to compare the use and utility of the different GSR testing techniques in a medical examiner setting. In Part I, the hands of deceased persons who died from undisputed suicidal handgun wounds were tested for GSR by SEM-EDX over a 4-year period. A total of 116 cases were studied and analyzed for caliber of weapon, proximity of wound, and results of GSR testing, including spatial deposition upon the hands. It was found that in only 50% of cases with a known self-inflicted gunshot wound was SEM-EDX positive for at least 1 specific particle for GSR. In 18% of the cases there was a discernible pattern (spatial distribution) of the particles on the hand such that the manner in which the weapon was held could be determined. Since only 50% of cases where the person is known to have fired a weapon immediately prior to death were positive for GSR by SEM-EDX, this test should not be relied upon to determine whether a deceased individual has discharged a firearm. Furthermore, in only 18% of cases was a discernible pattern present indicating how the firearm was held. The low sensitivity, along with the low percentage of cases with a discernible pattern, limits the usefulness of GSR test results by SEM-EDX in differentiating self-inflicted from non-self-inflicted wounds. PMID:17721163

Molina, D Kimberley; Martinez, Michael; Garcia, James; DiMaio, Vincent J M

2007-09-01

65

Spectral analysis of X-ray binaries  

E-print Network

In this thesis, I present work from three separate research projects associated with observations of X-ray binaries. Two of those revolve around spectral characteristics of neutron star low-mass X-ray binaries (NS-LMXBs), ...

Fridriksson, Joel Karl

2011-01-01

66

RFX x-ray pulse height analysis system  

NASA Astrophysics Data System (ADS)

The x-ray pulse height analysis diagnostic designed and built for the RFX reversed field pinch experiment is presented. The system is designed so as to be sensitive over a wide range of RFX operational conditions (100 eV ?Te ? 2 keV). An array of three liquid N2 cooled Si(Li) detectors looks at the plasma through an equatorial port of the torus and can be tilted ±20° off the plane in order to scan over the central half of the minor diameter on a shot-to-shot basis. A second windowless single detector views the plasma along a fixed chord through a second equatorial port and is sensitive to x-ray energies as low as 500 eV. Commercial electronics are mostly used. The throughput is limited only by the shaping amplifier and pulse pileup rejector. Software simulation of the x-ray flux, including the pulse pileup rejection procedure of the electronic chain, was used to dimension the diagnostic, i.e., number of detectors, size of the apertures, and filter combinations. Preliminary tests indicate 20 ms as a realistic target for the electron temperature time resolution, reducible to 5 ms when all of the four detectors are addressed to the same properly chosen x-ray energy region.

Carraro, L.; Valisa, M.

1990-10-01

67

Advances in X-Ray Chemical Analysis, Japan, 45 (2014) ISSN 0911-7806 Portable X-Ray Reflectometer Using  

E-print Network

Advances in X-Ray Chemical Analysis, Japan, 45 (2014) ISSN 0911-7806 © X X Portable X-Ray Reflectometer Using a Low Power Polychromatic X-Ray Tube Tsunemasa OHNISHI, Susumu IMASHUKU, Koretaka YUGE, Jun KAWAI and Naomi SHIMURA #12;#12;45 211 X X Adv. X-Ray. Chem. Anal., Japan 45, pp.211-215 (2014) 606

Jun, Kawai

68

Feasibility of coherent X-ray production by X-ray pumping. [inverting electron population in lithium  

NASA Technical Reports Server (NTRS)

It is suggested that coherent X-rays can be produced by inverting the electron population in a suitable target, such as Li, through irradiation with X-rays generated by fast electrons traversing an electromagnetic field (as in a storage ring). Conditions to be satisfied by target and radiation parameters are stated, and examples given.

Csonka, P. L.; Crasemann, B.

1974-01-01

69

Exotic X-ray Sources from Intermediate Energy Electron Beams  

NASA Astrophysics Data System (ADS)

High intensity x-ray beams are used in a wide variety of applications in solid-state physics, medicine, biology and material sciences. Synchrotron radiation (SR) is currently the primary, high-quality x-ray source that satisfies both brilliance and tunability. The high cost, large size and low x-ray energies of SR facilities, however, are serious limitations. Alternatively, "novel" x-ray sources are now possible due to new small linear accelerator (LINAC) technology, such as improved beam emittance, low background, sub-Picosecond beam pulses, high beam stability and higher repetition rate. These sources all stem from processes that produce Radiation from relativistic Electron beams in (crystalline) Periodic Structures (REPS), or the periodic "structure" of laser light. REPS x-ray sources are serious candidates for bright, compact, portable, monochromatic, and tunable x-ray sources with varying degrees of polarization and coherence. Despite the discovery and early research into these sources over the past 25 years, these sources are still in their infancy. Experimental and theoretical research are still urgently needed to answer fundamental questions about the practical and ultimate limits of their brightness, mono-chromaticity etc. We present experimental results and theoretical comparisons for three exotic REPS sources. These are Laser-Compton Scattering (LCS), Channeling Radiation (CR) and Parametric X-Radiation (PXR).

Chouffani, K.; Wells, D.; Harmon, F.; Jones, J. L.; Lancaster, G.

2003-08-01

70

Lipid Bilayer Structure Determined by the Simultaneous Analysis of Neutron and X-Ray Scattering Data  

E-print Network

Lipid Bilayer Structure Determined by the Simultaneous Analysis of Neutron and X-Ray Scattering) and dipalmitoylphosphatidylcholine (DPPC) bilayers by simultaneously analyzing x-ray and neutron scattering data. The neutron data electron and neutron scattering density profiles. A key result of the analysis is the molecular surface

Nagle, John F.

71

The History of X-ray Free-Electron Lasers  

SciTech Connect

The successful lasing at the SLAC National Accelerator Laboratory of the Linear Coherent Light Source (LCLS), the first X-ray free-electron laser (X-ray FEL), in the wavelength range 1.5 to 15 {angstrom}, pulse duration of 60 to few femtoseconds, number of coherent photons per pulse from 10{sup 13} to 10{sup 11}, is a landmark event in the development of coherent electromagnetic radiation sources. Until now electrons traversing an undulator magnet in a synchrotron radiation storage ring provided the best X-ray sources. The LCLS has set a new standard, with a peak X-ray brightness higher by ten orders of magnitudes and pulse duration shorter by three orders of magnitudes. LCLS opens a new window in the exploration of matter at the atomic and molecular scales of length and time. Taking a motion picture of chemical processes in a few femtoseconds or less, unraveling the structure and dynamics of complex molecular systems, like proteins, are some of the exciting experiments made possible by LCLS and the other X-ray FELs now being built in Europe and Asia. In this paper, we describe the history of the many theoretical, experimental and technological discoveries and innovations, starting from the 1960s and 1970s, leading to the development of LCLS.

Pellegrini, C.; /UCLA /SLAC; ,

2012-06-28

72

Nondestructive analysis of single crystals of selenide spinels by X-ray spectrometry techniques  

Microsoft Academic Search

The paper presents possibilities and difficulties in nondestructive analysis of small multielement single crystals performed\\u000a by means of X-ray spectrometry techniques: micro-X-ray fluorescence spectrometry (?-XRF), energy-dispersive electron probe\\u000a microanalysis (ED-EPMA), and X-ray photoelectron spectroscopy (XPS). The capability of the X-ray spectroscopy techniques in\\u000a elemental analysis is demonstrated with the single crystals of selenide spinels of the general formula M\\u000a x

E. Malicka; R. Sitko; B. Zawisza; J. Heimann; D. Kajewski; A. Kita

2011-01-01

73

Molecular and elemental characterisation of mineral particles by means of parallel micro-Raman spectrometry and Scanning Electron Microscopy/Energy Dispersive X-ray Analysis  

NASA Astrophysics Data System (ADS)

The "fingerprinting" of a molecular structure obtained by micro-Raman spectroscopy (MRS) can be successfully complemented by means of X-ray spot analysis through the application of scanning electron microscopy equipped with an X-ray detector (SEM/EDX). The elemental composition revealed by SEM/EDX is essential for a correct interpretation of the collected Raman spectra. The results presented here illustrate how the two techniques can be combined to characterize geological samples, especially in the case of individual particles. The samples involved in the experiments were Zr- and Ti-bearing sand from South Africa (with major minerals such as zircon and rutile) and U mine tailings from Hungary (rich with feldspars, quartz and sulphate minerals). Mineral phases detected by MRS were identified according to their respective main Raman shifts, with a spatial resolution up to 1 ?m, depending on the parameters set. Some unusual and sometimes inexplicable Raman activity was observed, which was ascribed to and rationalized by the presence of accompanying elements as detected with EDX. The relocation of a particle by means of the two instruments was facilitated with TEM grids. Although the limitations of the sequential use of SEM/EDX and MRS, such as different beam sizes, probing depth and surface topography, should be considered in their application to the analysis of individual geological particles, the two methods appeared to be complementary. Not only do they provide correlated chemical information about the sample, but also enable chemical characterization that would be otherwise incomplete when analyzed on a stand-alone basis.

Stefaniak, E. A.; Worobiec, A.; Potgieter-Vermaak, S.; Alsecz, A.; Török, S.; Van Grieken, R.

2006-07-01

74

THE EUROPEAN X-RAY FREE ELECTRON LASER PROJECT  

Microsoft Academic Search

The X-ray Free Electron Laser XFEL is a 4 th generation synchrotron radiation facility based on the SASE FEL concept and the superconducting TESLA technology for the linear accelerator. In February, 2003, the German Federal Ministry of Education and Research decided that the XFEL, proposed by the International TESLA Collaboration, should be realized as a European project and located at

A. S. Schwarz

2004-01-01

75

ELECTRON INJECTORS FOR NEXT GENERATION X-RAY SOURCES.  

SciTech Connect

Next generation x-ray sources require very high-brightness electron beams that are typically at or beyond the present state-of-the-art, and thus place stringent and demanding requirements upon the electron injector parameters. No one electron source concept is suitable for all the diverse applications envisaged, which have operating characteristics ranging from high-average-current, quasi-CW, to high-peak-current, single-pulse electron beams. Advanced Energy Systems, in collaboration with various partners, is developing several electron injector concepts for these x-ray source applications. The performance and design characteristics of five specific RF injectors, spanning ''L'' to ''X''-band, normal-conducting to superconducting, and low repetition rate to CW, which are presently in various stages of design, construction or testing, is described. We also discuss the status and schedule of each with respect to testing.

BLUEM,H.; BEN-ZVI,I.; SRINIVASAN-RAO,T.; ET AL.

2004-08-02

76

Parametric X-ray radiation along relativistic electron velocity in asymmetric Laue geometry  

Microsoft Academic Search

An analysis is presented of the parametric X-ray radiation emitted by a relativistic electron at a small angle to its velocity\\u000a as it passes through a single-crystal plate in asymmetric Laue geometry (including symmetric geometry as a particular case).\\u000a Expressions describing the spectral-angular distributions of parametric X-ray radiation, transition radiation, and their interference\\u000a are obtained. The effect of asymmetry on

S. V. Blazhevich; A. V. Noskov

2009-01-01

77

Parametric X-ray radiation along relativistic electron velocity in asymmetric Laue geometry  

SciTech Connect

An analysis is presented of the parametric X-ray radiation emitted by a relativistic electron at a small angle to its velocity as it passes through a single-crystal plate in asymmetric Laue geometry (including symmetric geometry as a particular case). Expressions describing the spectral-angular distributions of parametric X-ray radiation, transition radiation, and their interference are obtained. The effect of asymmetry on the spectral-angular distributions is examined.

Blazhevich, S. V. [Belgorod State University (Russian Federation); Noskov, A. V., E-mail: noskovbupk@mail.r [Belgorod University of Consumers' Cooperation (Russian Federation)

2009-12-15

78

Remote X-Ray Diffraction and X-Ray Fluorescence Analysis on Planetary Surfaces  

NASA Technical Reports Server (NTRS)

The legacy of planetary X-ray Diffraction (XRD) and X-ray Fluorescence (XRF) began in 1960 when W. Parish proposed an XRD instrument for deployment on the moon. The instrument was built and flight qualified, but the Lunar XRD program was cancelled shortly before the first human landing in 1969. XRF chemical data have been collected in situ by surface landers on Mars (Viking 1 & 2, Pathfinder) and Venus (Venera 13 & 14). These highly successful experiments provide critical constraints on our current understanding of surface processes and planetary evolution. However, the mineralogy, which is more critical to planetary surface science than simple chemical analysis, will remain unknown or will at best be imprecisely constrained until X-ray diffraction (XRD) data are collected. Recent progress in X-ray detector technology allows the consideration of simultaneous XRD (mineralogic analysis) and high-precision XRF (elemental analysis) in systems miniaturized to the point where they can be mounted on fixed landers or small robotic rovers. There is a variety of potential targets for XRD/XRF equipped landers within the solar system, the most compelling of which are the poles of the moon, the southern highlands of Mars and Europa.

Blake, David F.; DeVincenzi, D. (Technical Monitor)

1999-01-01

79

HARD X-RAY OBSERVATIONS OF A JET AND ACCELERATED ELECTRONS IN THE CORONA  

SciTech Connect

We report the first hard X-ray observation of a solar jet on the limb with flare footpoints occulted, so that faint emission from accelerated electrons in the corona can be studied in detail. In this event on 2003 August 21, RHESSI observed a double coronal hard X-ray source in the pre-impulsive phase at both thermal and nonthermal energies. In the impulsive phase, the first of two hard X-ray bursts consists of a single thermal/nonthermal source coinciding with the lower of the two earlier sources, and the second burst shows an additional nonthermal, elongated source, spatially and temporally coincident with the coronal jet. Analysis of the jet hard X-ray source shows that collisional losses by accelerated electrons can deposit enough energy to generate the jet. The hard X-ray time profile above 20 keV matches that of the accompanying Type III and broadband gyrosynchrotron radio emission, indicating both accelerated electrons escaping outward along the jet path and electrons trapped in the flare loop. The double coronal hard X-ray source, the open field lines indicated by Type III bursts, and the presence of a small post-flare loop are consistent with significant electron acceleration in an interchange reconnection geometry.

Glesener, Lindsay; Lin, R. P.; Krucker, Saem, E-mail: glesener@ssl.berkeley.edu [Space Science Laboratory, UC Berkeley, 7 Gauss Way, Berkeley, CA 94720 (United States)

2012-07-20

80

OSO-8 soft X-ray wheel experiment: Data analysis  

NASA Technical Reports Server (NTRS)

The soft X-ray experiment hardware and its operation are described. The device included six X-ray proportional counters, two of which, numbers 1 and 4, were pressurized with on-board methane gas supplies. Number 4 developed an excessive leak rate early in the mission and was turned off on 1975 day number 282 except for brief (typically 2-hour) periods up to day 585 after which it as left off. Counter 1 worked satisfactorily until 1975 day number 1095 (January 1, 1978) at which time the on-board methane supply was depleted. The other four counters were sealed and all except number 3 worked satisfactorily throughout the mission which terminated with permanent satellie shut-down on day 1369. This was the first large area thin-window, gas-flow X-ray detector to be flown in orbit. The background problems were severe and consumed a very large portion of the data analysis effort. These background problems were associated with the Earth's trapped electron belts.

Kraushaar, W. L.

1982-01-01

81

Search for X-rays and relativistic electrons in laboratory discharge experiments  

NASA Astrophysics Data System (ADS)

In 2013 discharge experiments were carried out at the Technical University of Eindhoven. The experimental set-up was designed to search for both X-rays and electrons produced in meter-scale sparks using a 1 MV Marx generator. In this paper we present the spatial distribution of signals and examine whether they are X-rays only or X-rays and electrons. Other characteristics of the signals will be presented as well. These experiments are carried out in the context of a larger effort to understand the various phenomena of X-rays and gammas from natural lightning. We acknowledge Z. Scherrer, K. Weber and K. LeCaptain at the Carthage college for supporting the initial data-analysis.

Ostgaard, Nikolai; Carlson, Brant E.; Grøndahl, Øystein; Kochkin, Pavlo; Nisi, Ragnhild S.; Gjesteland, Thomas

2014-05-01

82

Fundamental physics at an X-ray free electron laser  

Microsoft Academic Search

X-ray free electron lasers (FELs) have been proposed to be constructed both at SLAC in the form of the so-called Linac Coherent Light Source as well as at DESY, where the so-called XFEL laboratory is part of the design of the electron-positron linear collider TESLA. In addition to the immediate applications in condensed matter physics, chemistry, material science, and structural

A. Ringwald

2001-01-01

83

PARTICULATE MATTER ELEMENTAL COMPOSITION BY X-RAY FLUORESCENCE ANALYSIS  

EPA Science Inventory

This task is primarily concerned with the elemental characterization, by X-ray fluorescence analysis, of particulate matter (PM) collected during active or passive sampling of ambient air. The NERL X-ray fluorescence laboratory is an in-house research facility dedicated to quant...

84

X-ray Peltier cooled detectors for X-ray fluorescence analysis  

Microsoft Academic Search

The recent results on development of X-ray Si(Li), Si-planar and CdTe p-i-n detectors cooled by Peltier coolers for fabrication of laboratory and portable XRF analysers for different applications are discussed.Low detection limits of XRF analysers are provided by increasing of detectors sensitive surface; improvement of their spectrometrical characteristics; decreasing of front-end-electronics noise level; Peltier coolers and vacuum chambers cooling modes

A. Loupilov; A. Sokolov; V. Gostilo

2001-01-01

85

A compact x-ray free electron laser  

SciTech Connect

We present a design concept and simulation of the performance of a compact x-ray, free electron laser driven by ultra-high gradient rf-linacs. The accelerator design is based on recent advances in high gradient technology by a LLNL/SLAC/LBL collaboration and on the development of bright, high current electron sources by BNL and LANL. The GeV electron beams generated with such accelerators can be concerted to soft x-rays in the range from 2--10 nm by passage through short period, high fields strength wigglers as are being designed at Rocketdyne. Linear light sources of this type can produce trains of picosecond (or shorter) pulses of extremely high spectral brilliance suitable for flash holography of biological specimens in vivo and for studies of fast chemical reactions. 12 refs., 8 figs., 4 tabs.

Barletta, W.; Attac, M.; Cline, D.B.; Kolonko, J.; Wang, X.; Bhowmik, A.; Bobbs, B.; Cover, R.A.; Dixon, F.P.; Rakowsky, G.; Gallardo, J.; Pellegrini, C.; Westenskow, G.

1988-09-09

86

Spectral Analysis of X-Ray Binaries  

NASA Astrophysics Data System (ADS)

In this thesis, I present work from three separate research projects associated with observations of X-ray binaries. Two of those revolve around spectral characteristics of neutron star low-mass X-ray binaries (NS-LMXBs), with a particular source, XTE J1701-462, playing a central role. First, I construct and study color-color and hardness-intensity diagrams (CDs and HIDs) for a large sample of NS-LMXBs using Rossi X-ray Timing Explorer (RXTE) data spanning ~15 years. I study in particular detail three sources whose complicated CDs/HIDs are strongly affected by secular motion -- Cyg X-2, Cir X-1, and GX 13+1 -- and show that Cyg X-2 and Cir X-1 display CD/HID evolution with strong similarities to the transient Z source XTE J1701-462, which was previously shown to have evolved through all subclasses of NS-LMXBs as a result of changes in mass accretion rate. I build on the results for XTE J1701-462, Cyg X-2, and Cir X-1 and rank all the sources in the sample based only on their CD/HID morphology. I speculate that this represents a rough ranking in terms of the relative ranges in mass accretion rate experienced by the sources. Next, I use data from RXTE, Swift, Chandra, and XMM-Newton to study the transition to quiescence and the first ~1200 days of the quiescent phase of XTE J1701-462 following the end of its extraordinarily luminous 19 month outburst in 2006-2007. I find that the crust of the neutron star cooled rapidly during the first ~200 days of quiescence, after having been heated out of thermal equilibrium with the core during the outburst; the source has subsequently shown slower cooling along with sporadic low-level accretion activity. I discuss the implications of the observed cooling behavior and low-level accretion, the former of which yields information on the internal properties of the neutron star. Finally, I use multiple Chandra observations to study the X-ray source populations in the late-type galaxies NGC 6946 and NGC 4485/4490. A particular emphasis is placed on investigating the long-term variability of the sources, several of which are ultraluminous. I present detailed source catalogs and characterize the populations -- which consist primarily of X-ray binaries -- using X-ray luminosity functions and CDs.

Fridriksson, Joel K.

2011-09-01

87

Uncertainty estimates for electron probe X-ray microanalysis measurements.  

PubMed

It has been over 60 years since Castaing (Castaing, R. Application of Electron Probes to Local Chemical and Crystallographic Analysis. Ph.D. Thesis, University of Paris, Paris, France, 1951; translated by P. Duwez and D. Wittry, California Institute of Technology, 1955) introduced the technique of electron probe X-ray microanalysis (EPMA), yet the community remains unable to quantify some of the largest terms in the technique's uncertainty budget. Historically, the EPMA community has assigned uncertainties to its measurements which reflect the measurement precision portion of the uncertainty budget and omitted terms related to the measurement accuracy. Yet, in many cases, the precision represents only a small fraction of the total budget. This paper addresses this shortcoming by considering two significant sources of uncertainty in the quantitative matrix correction models--the mass absorption coefficient, [?/?], and the backscatter coefficient, ?. Understanding the influence of these sources provides insight into the utility of EPMA measurements, and equally important, it allows practitioners to develop strategies to optimize measurement accuracy by minimizing the influence of poorly known model parameters. PMID:23088729

Ritchie, Nicholas W M; Newbury, Dale E

2012-11-20

88

Bulk sensitive hard x-ray photoemission electron microscopy.  

PubMed

Hard x-ray photoelectron spectroscopy (HAXPES) has now matured into a well-established technique as a bulk sensitive probe of the electronic structure due to the larger escape depth of the highly energetic electrons. In order to enable HAXPES studies with high lateral resolution, we have set up a dedicated energy-filtered hard x-ray photoemission electron microscope (HAXPEEM) working with electron kinetic energies up to 10 keV. It is based on the NanoESCA design and also preserves the performance of the instrument in the low and medium energy range. In this way, spectromicroscopy can be performed from threshold to hard x-ray photoemission. The high potential of the HAXPEEM approach for the investigation of buried layers and structures has been shown already on a layered and structured SrTiO3 sample. Here, we present results of experiments with test structures to elaborate the imaging and spectroscopic performance of the instrument and show the capabilities of the method to image bulk properties. Additionally, we introduce a method to determine the effective attenuation length of photoelectrons in a direct photoemission experiment. PMID:25430117

Patt, M; Wiemann, C; Weber, N; Escher, M; Gloskovskii, A; Drube, W; Merkel, M; Schneider, C M

2014-11-01

89

A case of hut lung: scanning electron microscopy with energy dispersive x-ray spectroscopy analysis of a domestically acquired form of pneumoconiosis.  

PubMed

Hut lung is a pneumoconiosis caused by exposure to smoke derived from biomass fuels used for cooking in poorly ventilated huts. We report, to our knowledge, the first analysis of the dust deposited in the lungs in hut lung by scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM/EDS). A Bhutanese woman presented with shortness of breath and an abnormal chest radiograph. Chest CT scan showed innumerable tiny bilateral upper lobe centrilobular nodules. Transbronchial biopsy revealed mild interstitial fibrosis with heavy interstitial deposition of black dust. SEM/EDS showed that the dust was carbonaceous, with smaller yet substantial numbers of silica and silicate particles. Additional history revealed use of a wood/coal-fueled stove in a small, poorly ventilated hut for 45 years. The possibility of hut lung should be considered in women from countries where use of biomass-fueled stoves for cooking is common. Our findings support the classification of this condition as a mixed-dust pneumoconiosis. PMID:23880681

Mukhopadhyay, Sanjay; Gujral, Manmeet; Abraham, Jerrold L; Scalzetti, Ernest M; Iannuzzi, Michael C

2013-07-01

90

Characterization of ferroelectric ceramics using x-ray diffraction, transmission electron microscopy, and x-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

Ferroelectric ceramic samples of PbTiO3, prepared by a modified oxide-mixing technique, were examined by x-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques for crystalline and microstructural characterization. XRD clearly revealed only a monophasic perovskite of tetragonal symmetry for the reference PbTiO3, which was established to possess both a-a-and a-c-type 90° domains. The inclination was approximately 2° between the two different domains, as observed by high-resolution TEM. Inductively coupled plasma (ICP) analysis, electron probe microanalysis (EPMA), and x-ray photoelectron spectroscopy (XPS) were employed and the ensuing chemical composition results are discussed. The approximate molar ratios of Pb:Ti were 1:1, 1:1.5, and 1:0.8 as obtained by ICP analysis, EPMA, and XPS, respectively. Corrections for the sensitivity factor (SCorr) for Pb 4f, Ti 2p and the substitution of the matrix factors for FTi,Pb, FPb,Ti have been taken into account in obtaining the Pb:Ti ratio of 1:1 by XPS quantification. The sensitivity factor (SKratos) given by the instrumental maker was compared with the theoretical one (STheo) and the result is also discussed.

Kim, Jae-Nam; Shin, Kwang-Soo; Park, Byung-Ok; Lee, Jin-Hong; Kim, Nam-Kyoung; Cho, Sang-Hee

2003-08-01

91

Druse clinopyroxene in D'Orbigny angritic meteorite studied by single-crystal X-ray diffraction, electron microprobe analysis, and Mössbauer spectroscopy  

NASA Astrophysics Data System (ADS)

The crystal structure of druse clinopyroxene from the D’Orbigny angrite, (Ca0.944 Fe2+ 0.042 Mg0.010Mn0.004) (Mg0.469Fe2+ 0.317Fe3+ 0.035Al0.125Cr0.010Ti0.044) (Si1.742Al0.258) O6, a = 9.7684(2), b = 8.9124(2), c = 5.2859(1) Å, ? = 105.903(1)°, V = 442.58 Å3, space group C2/c, Z = 2, has been refined to an R1 index of 1.92% using single-crystal X-ray diffraction data. The unit formula, calculated from electron microprobe analysis, and the refined site scattering values were used to assign site populations. The distribution of Fe2+ and Mg over the M1 and M2 sites suggests a closure temperature of 1000 °C. Mössbauer spectroscopy measurements were done at room temperature on a single crystal and a powdered sample. The spectra are adequately fit by a Voigt-based quadrupole-splitting distribution model having two generalized sites, one for Fe2+ with two Gaussian components and one for Fe3+ with one Gaussian component. The two ferrous components are assigned to Fe2+ at the M1 site, and arise from two different next-nearest-neighbor configurations of Ca and Fe cations at the M2 site: (3Ca,0Fe) and (2Ca,1Fe). The Fe3+/Fetot ratio determined by Mössbauer spectroscopy is in agreement with that calculated from the electron microprobe analysis. The results are discussed in connection with the redox and thermal history of D’Orbigny.

Abdu, Y. A.; Scorzelli, R. B.; Varela, M. E.; Kurat, G.; de Souza Azevedo, I.; Stewart, S. J.; Hawthorne, F. C.

2009-05-01

92

X ray microscope assembly and alignment support and advanced x ray microscope design and analysis  

NASA Technical Reports Server (NTRS)

Considerable efforts have been devoted recently to the design, analysis, fabrication, and testing of spherical Schwarzschild microscopes for soft x ray application in microscopy and projection lithography. The spherical Schwarzschild microscope consists of two concentric spherical mirrors configured such that the third order spherical aberration and coma are zero. Since multilayers are used on the mirror substrates for x ray applications, it is desirable to have only two reflecting surfaces in a microscope. In order to reduce microscope aberrations and increase the field of view, generalized mirror surface profiles have been considered in this investigation. Based on incoherent and sine wave modulation transfer function (MTF) calculations, the object plane resolution of a microscope has been analyzed as a function of the object height and numerical aperture (NA) of the primary for several spherical Schwarzschild, conic, and aspherical head reflecting two mirror microscope configurations.

Shealy, David L.

1991-01-01

93

X-ray photoabsorption and total electron yield of Fe thin films at the L 2,3 edge  

Microsoft Academic Search

We have studied thin Fe films by soft X-ray absorption spectroscopy to determine the total electron yield (TEY) sampling depth (?e) at the Fe L2,3 edge. For this, we have recorded high-resolution X-ray absorption spectra in TEY resolving the near edge X-ray absorption fine structure (NEXAFS). Our analysis yields a value of ?e=21±2Å for the TEY sampling depth.

Y. Ufuktepe; G. Akgül; J. Lüning

2005-01-01

94

IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS 1 Coherent X-ray Diffraction Imaging  

E-print Network

and X-ray free-electron lasers are presently under rapid development worldwide, coherent diffraction, oversampling, phase retrieval, X-ray free-electron lasers (XFEL). I. INTRODUCTION MICROSCOPY has found broad

Miao, Jianwei "John"

95

Note: Studies on x-ray production in electron cyclotron resonance x-ray source based on ridged cylindrical cavity  

SciTech Connect

A ridged cylindrical cavity has been designed using MICROWAVE STUDIO programme and it is used in the electron cyclotron resonance (ECR) x-ray source. The experimental parameters of the source are optimized for maximizing the x-ray output, and an x-ray dose rate of {approx}1000 {mu}Sv/h was observed at 20 cm from the port, for 500 W of microwave power without using any target. With the molybdenum target located at optimum position of the ridged cavity, the dose rate is found to be increased only by 10%. In order to understand the experimental observation, the electric field pattern of the cavity with the target placed at various radial distances is studied. In this note, the experimental and theoretical studies on ECR x-ray source using the ridged cylindrical cavity are presented.

Selvakumaran, T. S.; Baskaran, R. [Radiological Safety Division, Indira Gandhi Center for Atomic Research, Kalpakkam, Tamilnadu 603102 (India)

2012-02-15

96

The angular distribution of energetic electron and X-ray emissions from triggered lightning leaders  

NASA Astrophysics Data System (ADS)

We investigate individual X-ray bursts from lightning leaders to determine if energetic electrons at the source (and hence X-rays) are emitted isotropically or with some degree of anisotropy. This study was motivated by the work of Saleh et al. (2009), which found the falloff of X-rays in concentric radial annuli, covering all azimuthal directions in each annulus, from the lightning channel to be most consistent with an isotropic electron source. Here we perform a statistical analysis of angular and spatial distributions of X-rays measured by up to 21 NaI/PMT detectors at the International Center for Lightning Research and Testing site for 21 leader X-ray bursts from five leaders (including four dart-stepped leaders and one dart leader). Two procedures were used to complete this analysis. Procedure 1 found the first-order anisotropy, and procedure 2 tested whether or not the angular distribution was consistent with an isotropic distribution. Because higher-order anisotropies could be present in the data, a distribution that is not isotropic does not necessarily have a significant first-order anisotropy. Using these procedures, we find that at least 11 out of 21 X-ray bursts have a statistically significant first-order anisotropy, and hence those 11 are inconsistent with an isotropic emission. The remaining 10 bursts do not have significant first-order anisotropy. However, of those 10 bursts, 9 are inconsistent with isotropic emission, since they exhibit significant higher-order anisotropies. Since Saleh et al. (2009) did not consider anisotropies in the azimuthal direction, these new measurements of anisotropy do not necessarily contradict that work. Indeed, our analysis supports the finding that the X-ray emissions from lightning are inconsistent with a vertically downward beam. The level of anisotropy of the runaway electrons is important because it provides, in principle, information on the streamer zone in front of the leader and the electric field near the lightning leader tip.

Schaal, M. M.; Dwyer, J. R.; Rassoul, H. K.; Hill, J. D.; Jordan, D. M.; Uman, M. A.

2013-10-01

97

Atmospheric Electron-Induced X-Ray Spectrometer (AEXS) Development  

NASA Technical Reports Server (NTRS)

This paper describes the progress in the development of the so-called Atmospheric Electron X-ray Spectrometer (AEXS) instrument in our laboratory at JPL. The AEXS is a novel miniature instrument concept based on the excitation of characteristic X-Ray Fluorescence (XRF) and luminescence spectra using a focused electron beam, for non-destructive evaluation of surfaces of samples in situ, in planetary ambient atmosphere. In situ operation is obtained through the use of a thin electron transmissive membrane to isolate the vacuum within the AEXS electron source from the outside ambient atmosphere. By using a focused electron beam, the impinging electrons on samples in the external atmosphere excite XRF spectra from the irradiated spots with high-to-medium spatial resolution. The XRF spectra are analyzed using an energy-dispersive detector to determine surface elemental composition. The use of high- intensity electron beam results in rapid spectrum acquisition (several minutes), and consequently low energy consumption (several tens of Joules) per acquired XRF spectrum in comparison to similar portable instruments.

Wilcox, Jaroslava Z.; Urgiles, Eduardo; Toda, Risaku; George, Thomas; Douglas, Susanne; Crisp, Joy

2005-01-01

98

Femtosecond diffractive imaging with a soft-X-ray free-electron laser  

E-print Network

LETTERS Femtosecond diffractive imaging with a soft-X-ray free-electron laser HENRY N. CHAPMAN1 of this principle using the FLASH soft-X-ray free-electron laser. An intense 25 fs, 4 Ã? 1013 W cm-2 pulse by one10 . X-ray free-electron lasers (FELs) are expected to permit diffractive imaging at high

Loss, Daniel

99

Selective photo-activation analysis with laser-driven x-rays  

NASA Astrophysics Data System (ADS)

We discuss a technique for the identification of nuclear isotopes by selective photo-activation analysis. A narrow divergence beam of high-energy photons is produced when a laser driven electron beam Compton backscatters off a counter-propagating high-intensity laser pulse. The x-rays from this compact laser-driven synchrotron light source are MeV energy, narrow-bandwidth, tunable, polarized, and bright (10^8 photons s-1). Such characteristics make these x-rays well-suited for nuclear interrogation by means of triggering (?,f) and (?,xn) reactions. The narrow bandwidth of the x-ray light can be exploited to selectively activate nuclei with isotopic sensitivity, without causing unwanted background from collateral activation. Additionally, the polarized nature of the x-rays can be used to study anisotropy of neutron emission, for precise identification of isotopes. Activation by laser-driven synchrotron x-rays will be compared with activation by bremsstrahlung.

Banerjee, Sudeep; Golovin, Grigory; Powers, Nathan; Liu, Cheng; Chen, Shouyuan; Petersen, Chad; Zhang, Jun; Ghebregziabher, Isaac; Zhao, Baozhen; Brown, Kevin; Mills, Jared; Umstadter, Donald; Haden, Dan; Silano, Jack; Karwowski, Hugon

2013-04-01

100

A technique for calibrating an electron-beam evaporator x-ray source  

Microsoft Academic Search

An electron-beam metal evaporator was modified to act as an x-ray source for simulating x-ray lithography induced radiation damage in semiconductor devices. Besides x-rays, such a set-up generates secondary and backscattered electrons. Simulation of radiation damage induced during a typical x-ray lithography processing step requires that secondary and backscattered electrons be removed from the incident radiation. A common method to

Robert J. Kinzig

1991-01-01

101

Kilometer scale structures in auroral X ray arcs detected by combining satellite X ray images with in situ energetic electron flux profiles  

SciTech Connect

This paper reports on analysis of combined x-ray and electron energy measurements by satellite of auroral arcs, to reveal more information on the spatial scale of the arcs. Bremsstrahlung radiation from precipitating electrons of auroral arcs stopping in the earths atmosphere provide x-ray images of the regions of the arcs. They have the advantage that a satellite can sense them from a distance, and thus can sample a larger area than just the path of its orbit. The x-ray images also reveal narrower features than seen from optical emission. Here x-ray images from the XRIS imager on the S81-1 polar orbiting satellite are analyzed. 4 to 40 keV x-rays were observed, with the 40 km resolution of the XRIS imager. However, by combining this with high time resolution measurements of electrons with energies above 16 keV, which could be measured along the satellite track, one can see 2 km spatial features. These measurements showed km scale structure within the auroral arcs.

Datlowe, D.W.; Imhof, W.L.; Voss, H.D. (Lockheed Palo Alto Research Lab., CA (United States))

1993-06-01

102

Analysis of the electronic and local structure of amorphous SiNx:H alloy films in terms of SiK, SiL, and NK x-ray emission bands  

NASA Astrophysics Data System (ADS)

We have studied silicon-nitrogen bonding states in amorphous SiNx:H alloy films and in crystalline ?-Si3N4 and ?-Si3N4 by applying x-ray-emission spectroscopy (XES). We present x-ray Si K, Si L, and N K emission bands of alloy films covering the concentration range 0<=x<=2.03 and identify spectral features on the base of ab initio calculations of all emission bands of ?-Si3N4. The calculations delineate the role of Si 3s, 3p, and N 2s, 2p electrons in the bond and confirm the presence of silicon d-like electrons in the top region of the valence band. A comparison with available ultraviolet and x-ray photoelectron spectroscopy results is given. The position of the N 2s line observed in Si K and Si L emission bands of the alloys is analyzed in terms of the random-bond and random-mixture (RMM) models of nearest-neighbor structure of silicon atoms. The results unambiguously support the RMM structure of our samples and demonstrate that a detailed analysis of x-ray transitions observable in XES can yield unique and unconventional information about the local structure and the degree of phase separation in a-SiNx:H alloy films.

Wiech, G.; Šim?nek, A.

1994-02-01

103

Glancing Angle Dependence of the X-Ray Emission Measured under Total Reflection Angle X-Ray Spectroscopy (TRAXS) Condition during Reflection High Energy Electron Diffraction Observation  

NASA Astrophysics Data System (ADS)

We measured the glancing angle (?g) dependence of the X-ray emission from Si(111)-\\sqrt{3}×\\sqrt{3}-Ag and ?-\\sqrt{3}×\\sqrt{3}-Au surfaces during Reflection High Energy Electron Diffraction observation under the Total Reflection Angle X-ray Spectroscopy condition. The characteristic X-rays AgL and AuM decreased according to 1/sin ?g. The function 1/\\sin?g is easily understood in terms of Ag and Au atoms located at the top layer of the surface. The SiK and the bremsstrahlung showed broad peaks around 8°. These trends of the curves are explained by an analysis using Monte Carlo electron trajectory simulation. By measuring the glancing angle dependence we can easily distinguish whether or not a specific kind of atom is confined at the top layer of the surface.

Yamanaka, Toshiro; Hanada, Takashi; Ino, Shozo; Daimon, Hiroshi

1992-10-01

104

Electron microprobe X-ray microanalysis of diseased coconut ( Cocos nucifera ) roots  

Microsoft Academic Search

Summary Electron microprobe X-ray analysis of root (wilt) diseased and healthy coconut roots were scanned for the deposition of metal ions to implicate the involvement of these metal toxicity in the root (wilt) disease of coconut. The results indicated that a high concentration of Al, Mn, Cu and Co ions localised in the disease roots compared to healthy palms. The

C. C. Biddappa; S. Rober Cecil

1984-01-01

105

University of California electron and X-ray experiments on ISEE-3  

NASA Technical Reports Server (NTRS)

The history of the University of California solar and interplanetary electron experiment and the solar X-ray experiment is outlined, and the two instruments used are described. The roles of personnel are mentioned and the data analysis projects completed or begun are summarized. A bibliography is included.

Anderson, K. A.

1981-01-01

106

Measurement of total calcium in neurons by electron probe X-ray microanalysis.  

PubMed

In this article the tools, techniques, and instruments appropriate for quantitative measurements of intracellular elemental content using the technique known as electron probe microanalysis (EPMA) are described. Intramitochondrial calcium is a particular focus because of the critical role that mitochondrial calcium overload plays in neurodegenerative diseases. The method is based on the analysis of X-rays generated in an electron microscope (EM) by interaction of an electron beam with the specimen. In order to maintain the native distribution of diffusible elements in electron microscopy specimens, EPMA requires "cryofixation" of tissue followed by the preparation of ultrathin cryosections. Rapid freezing of cultured cells or organotypic slice cultures is carried out by plunge freezing in liquid ethane or by slam freezing against a cold metal block, respectively. Cryosections nominally 80 nm thick are cut dry with a diamond knife at ca. -160 °C, mounted on carbon/pioloform-coated copper grids, and cryotransferred into a cryo-EM using a specialized cryospecimen holder. After visual survey and location mapping at ?-160 °C and low electron dose, frozen-hydrated cryosections are freeze-dried at -100 °C for ~30 min. Organelle-level images of dried cryosections are recorded, also at low dose, by means of a slow-scan CCD camera and subcellular regions of interest selected for analysis. X-rays emitted from ROIs by a stationary, focused, high-intensity electron probe are collected by an energy-dispersive X-ray (EDX) spectrometer, processed by associated electronics, and presented as an X-ray spectrum, that is, a plot of X-ray intensity vs. energy. Additional software facilitates: 1) identification of elemental components by their "characteristic" peak energies and fingerprint; and 2) quantitative analysis by extraction of peak areas/background. This paper concludes with two examples that illustrate typical EPMA applications, one in which mitochondrial calcium analysis provided critical insight into mechanisms of excitotoxic injury and another that revealed the basis of ischemia resistance. PMID:24300079

Pivovarova, Natalia B; Andrews, S Brian

2013-01-01

107

A new soft x-ray pulse height analysis array in the HL-2A tokamak  

NASA Astrophysics Data System (ADS)

A new soft x-ray pulse height analysis (PHA) array including nine independent subsystems, on basis of a nonconventional software multichannel analysis system and a silicon drift detector (SDD) linear array consisting of nine high performance SDD detectors, has been developed in the HL-2A tokamak. The use of SDD has greatly improved the measurement accuracy and the spatiotemporal resolutions of the soft x-ray PHA system. Since the ratio of peak to background counts obtained from the SDD PHA system is very high, p /b?3000, the soft x-ray spectra measured by the SDD PHA system can approximatively be regarded as electron velocity distribution. The electron velocity distribution can be well derived in the pure ohmic and auxiliary heating discharges. The performance of the new soft x-ray PHA array and the first experimental results with some discussions are presented.

Zhang, Y. P.; Liu, Yi; Yang, J. W.; Song, X. Y.; Liao, M.; Li, X.; Yuan, G. L.; Yang, Q. W.; Duan, X. R.; Pan, C. H.

2009-12-01

108

Characterization of acrylic polyamide plastic embolization particles in vitro and in human tissue sections by light microscopy, infrared microspectroscopy and scanning electron microscopy with energy dispersive X-ray analysis  

Microsoft Academic Search

Vascular embolization is a well-established practice for the treatment of tumors and vascular lesions. Rounded beads (microspheres) of various materials (collagen, dextran and trisacryl-polymer-gelatin) were developed to solve problems encountered with earlier versions of embolic material. We performed histochemistry, Fourier transform infrared microspectroscopy and scanning electron microscopy with energy dispersive X-ray analysis on two uterine and one hepatic specimen with

Linda A Murakata; Michael R Lewin-Smith; Charles S Specht; Victor F Kalasinsky; Peter L McEvoy; Tuyethoa N Vinh; Lionel N M I Rabin; Florabel G Mullick

2006-01-01

109

European X-Ray Free Electron Laser (EXFEL): local implications  

NASA Astrophysics Data System (ADS)

European X-Ray FEL - free electron laser is under construction in DESY Hamburg. It is scheduled to be operational at 2015/16 at a cost more than 1 billion Euro. The laser uses SASE method to generate x-ray light. It is propelled by an electron linac of 17,5GeV energy and more than 2km in length. The linac uses superconducting SRF TESLA technology working at 1,3 GHz in frequency. The prototype of EXFEL is FLASH Laser (200 m in length), where the "proof of principle" was checked, and from the technologies were transferred to the bigger machine. The project was stared in the nineties by building a TTF Laboratory -Tesla Test Facility. The EXFEL laser is a child of a much bigger teraelectronovolt collider project TESLA (now abandoned in Germany but undertaken by international community in a form the ILC). A number of experts and young researchers from Poland participate in the design, construction and research of the FLASH and EXFEL lasers.

Romaniuk, Ryszard S.

2013-10-01

110

Hard x-ray or gamma ray laser by a dense electron beam  

SciTech Connect

A dense electron beam propagating through a laser undulator can radiate a coherent x-ray or gamma ray. This lasing scheme is studied with the Landau damping theory. The analysis suggests that, with currently available physical parameters, coherent gamma rays of up to 50 keV can be generated. The electron quantum diffraction suppresses the free electron laser action, which limits the maximum radiation.

Son, S. [18 Caleb Lane, Princeton, New Jersey 08540 (United States); Joon Moon, Sung [8 Benjamin Rush Ln., Princeton, New Jersey 08540 (United States)

2012-06-15

111

Toward atomic resolution diffractive imaging of isolated molecules with x-ray free-electron lasers  

E-print Network

We give a detailed account of the theoretical analysis and the experimental results of an x-ray-diffraction experiment on quantum-state selected and strongly laser-aligned gas-phase ensembles of the prototypical large asymmetric rotor molecule 2,5-diiodobenzonitrile, performed at the Linac Coherent Light Source [Phys. Rev. Lett. 112, 083002 (2014)]. This experiment is the first step toward coherent diffractive imaging of structures and structural dynamics of isolated molecules at atomic resolution, i. e., picometers and femtoseconds, using x-ray free-electron lasers.

Stern, Stephan; Filsinger, Frank; Rouzée, Arnaud; Rudenko, Artem; Johnsson, Per; Martin, Andrew V; Barty, Anton; Bostedt, Christoph; Bozek, John D; Coffee, Ryan N; Epp, Sascha; Erk, Benjamin; Foucar, Lutz; Hartmann, Robert; Kimmel, Nils; Kühnel, Kai-Uwe; Maurer, Jochen; Messerschmidt, Marc; Rudek, Benedikt; Starodub, Dmitri G; Thøgersen, Jan; Weidenspointner, Georg; White, Thomas A; Stapelfeldt, Henrik; Rolles, Daniel; Chapman, Henry N; Küpper, Jochen

2014-01-01

112

Toward atomic resolution diffractive imaging of isolated molecules with X-ray free-electron lasers.  

PubMed

We give a detailed account of the theoretical analysis and the experimental results of an X-ray-diffraction experiment on quantum-state selected and strongly laser-aligned gas-phase ensembles of the prototypical large asymmetric rotor molecule 2,5-diiodobenzonitrile, performed at the Linac Coherent Light Source [Phys. Rev. Lett.112, 083002 (2014)]. This experiment is the first step toward coherent diffractive imaging of structures and structural dynamics of isolated molecules at atomic resolution, i.e., picometers and femtoseconds, using X-ray free-electron lasers. PMID:25415561

Stern, S; Holmegaard, L; Filsinger, F; Rouzée, A; Rudenko, A; Johnsson, P; Martin, A V; Barty, A; Bostedt, C; Bozek, J; Coffee, R; Epp, S; Erk, B; Foucar, L; Hartmann, R; Kimmel, N; Kühnel, K-U; Maurer, J; Messerschmidt, M; Rudek, B; Starodub, D; Thøgersen, J; Weidenspointner, G; White, T A; Stapelfeldt, H; Rolles, D; Chapman, H N; Küpper, J

2014-01-01

113

Food Irradiation Using Electron Beams and X-Rays  

NASA Astrophysics Data System (ADS)

In this presentation we will discuss the technology of food irradiation using electron accelerators. Food irradiation has generally come to describe the use of ionizing radiation to decrease the population of, or prevent the growth of, undesirable biological organisms in food. The many beneficial applications include insect disinfestation, sprouting inhibition, delayed ripening, and the enhanced safety and sterilization of fresh and frozen meat products, seafood, and eggs. With special regard to food safety, bacteria such as Salmonella enteridis, Listeria monocytogenes, Campylobacter jejuni and Escherichia coli serotype O157:H7 are the primary causes of food poisoning in industrialized countries. Ionizing doses in the range of only 1-5 kilogray (kGy) can virtually eliminate these organisms from food, without affecting the food's sensory and nutritional qualities, and without inducing radioactivity. The key elements of an accelerator-based irradiation facility include the accelerator system, a scanning system, and a material handling system that moves the product through the beam in a precisely controlled manner. Extensive radiation shielding is necessary to reduce the external dose to acceptable levels, and a safety system is necessary to prevent accidental exposure of personnel during accelerator operation. Parameters that affect the dose distribution must be continuously monitored and controlled with process control software. The choice of electron beam vs x-ray depends on the areal density (density times thickness) of the product and the anticipated mass throughput. To eliminate nuclear activation concerns, the maximum kinetic energy of the accelerator is limited by regulation to 10 MeV for electron beams, and 5 MeV for x-rays. From penetration considerations, the largest areal density that can be treated by double-sided electron irradiation at 10 MeV is about 8.8 g/cm2. Products having greater areal densities must be processed using more penetrating x-rays. The mass throughput (dM/dt in kg/s) of an accelerator-based system is proportional to the average beam power (P in kW), and inversely proportional to the minimum required dose (Dm in kGy, with 1 kGy = 1 kJ/kg). The constant of proportionality is the mass throughput efficiency. Throughput efficiencies of 0.4 or better are typical of electron beam installations, but are only 0.025-0.035 for x-ray installations, primarily because of the inefficiency of bremsstrahlung generation at 5 MeV (about 8an axially-coupled, standing-wave, L-band linac with an average power in excess of 100 kW to achieve reasonable throughput rates with x-ray processing. Various design aspects of this new machine will be presented.

Miller, Bruce

2003-04-01

114

X-ray emission as a diagnostic from pseudospark-sourced electron beams  

NASA Astrophysics Data System (ADS)

X-ray emission has been achieved using an electron beam generated by a pseudospark low-pressure discharge and utilised as a diagnostic for beam detection. A 300 A, 34 kV PS-sourced electron beam pulse of 3 mm diameter impacting on a 0.1 mm-thick molybdenum target generated X-rays which were detected via the use of a small, portable X-ray detector. Clear X-ray images of a micro-sized object were captured using an X-ray photodetector. This demonstrates the inducement of proton induced X-ray emission (PIXE) not only as an indicator of beam presence but also as a future X-ray source for small-spot X-ray imaging of materials.

Bowes, D.; Yin, H.; He, W.; Zhang, L.; Cross, A. W.; Ronald, K.; Phelps, A. D. R.; Chen, D.; Zhang, P.; Chen, X.; Li, D.

2014-09-01

115

GRB Swift X-ray light curves analysis (Margutti+, 2013)  

NASA Astrophysics Data System (ADS)

We present a comprehensive statistical analysis of Swift X-ray light curves of gamma-ray bursts (GRBs) collecting data from more than 650 GRBs discovered by Swift and other facilities. The unprecedented sample size allows us to constrain the rest-frame X-ray properties of GRBs from a statistical perspective, with particular reference to intrinsic time-scales and the energetics of the different light-curve phases in a common rest-frame 0.3-30keV energy band. Temporal variability episodes are also studied and their properties constrained. Two fundamental questions drive this effort: (i) Does the X-ray emission retain any kind of 'memory' of the prompt ?-ray phase? (ii) Where is the dividing line between long and short GRB X-ray properties? We show that short GRBs decay faster, are less luminous and less energetic than long GRBs in the X-rays, but are interestingly characterized by similar intrinsic absorption. We furthermore reveal the existence of a number of statistically significant relations that link the X-ray to prompt ?-ray parameters in long GRBs; short GRBs are outliers of the majority of these two-parameter relations. However and more importantly, we report on the existence of a universal three-parameter scaling that links the X-ray and the ?-ray energy to the prompt spectral peak energy of both long and short GRBs: EX,iso{prop.to}E1.00+/-0.06?,iso/E0.60+/-0.10pk. (3 data files).

Margutti, R.; Zaninoni, E.; Bernardini, M. G.; Chincarini, G.; Pasotti, F.; Guidorzi, C.; Angelini, L.; Burrows, D. N.; Capalbi, M.; Evans, P. A.; Gehrels, N.; Kennea, J.; Mangano, V.; Moretti, A.; Nousek, J.; Osborne, J. P.; Page, K. L.; Perri, M.; Racusin, J.; Romano, P.; Sbarufatti, B.; Stafford, S.; Stamatikos, M.

2013-11-01

116

Note: Studies on target placement in TE{sub 111} cylindrical cavity of electron cyclotron resonance x-ray source for the enhancement of x-ray dose  

SciTech Connect

X-ray source based on electron cyclotron resonance principle has been constructed using TE{sub 111} cylindrical cavity. At present the device is used to provide low energy x-ray field for thermoluminescent dosimeter badge calibration. Theoretical and experimental studies on the effect of target placement inside the TE{sub 111} cylindrical cavity for enhancing the x-ray output are carried out and the results are presented in this note. Optimum target location is identified by theoretical analysis on the electric field distribution inside the cavity using MICROWAVE STUDIO program. By modifying the magnetic field configuration, the resonance region is shifted to the optimum target location. The microwave transmission line is upgraded with a three stub tuner which improves the microwave coupling from the source to the target loaded cavity. Molybdenum target is located at a radial distance of 2.5 cm from the cavity center and the x-ray dose rate is measured at 20 cm from the exit port for different microwave power. With the introduction of the target, the x-ray output has improved nearly from 70% to 160% in the microwave power of 150-500 W.

Selvakumaran, T. S.; Baskaran, R.; Singh, A. K. [Safety Group, Radiological Safety Division, Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India); Sista, V. L. S. Rao [Nuclear Physics Division, Bhabha Atomic Research Center, Mumbai 400085 (India)

2010-03-15

117

Note: Studies on target placement in TE(111) cylindrical cavity of electron cyclotron resonance x-ray source for the enhancement of x-ray dose.  

PubMed

X-ray source based on electron cyclotron resonance principle has been constructed using TE(111) cylindrical cavity. At present the device is used to provide low energy x-ray field for thermoluminescent dosimeter badge calibration. Theoretical and experimental studies on the effect of target placement inside the TE(111) cylindrical cavity for enhancing the x-ray output are carried out and the results are presented in this note. Optimum target location is identified by theoretical analysis on the electric field distribution inside the cavity using MICROWAVE STUDIO program. By modifying the magnetic field configuration, the resonance region is shifted to the optimum target location. The microwave transmission line is upgraded with a three stub tuner which improves the microwave coupling from the source to the target loaded cavity. Molybdenum target is located at a radial distance of 2.5 cm from the cavity center and the x-ray dose rate is measured at 20 cm from the exit port for different microwave power. With the introduction of the target, the x-ray output has improved nearly from 70% to 160% in the microwave power of 150-500 W. PMID:20370227

Selvakumaran, T S; Baskaran, R; Singh, A K; Sista, V L S Rao

2010-03-01

118

Development of a quantification method for x-ray microanalysis with an electron microscope  

NASA Astrophysics Data System (ADS)

The overview of the history of quantitative x-ray microanalysis shows the efficiency of the use of standards to achieve the most reliable quantification. State-of-the-art cold field emission gun scanning electron microscopes offer excellent resolution but lack a sufficient level of beam current stability essential for reliable quantitative microanalysis. The purpose of this work is to develop a new method for quantitative x-ray microanalysis adapted to unstable beam current conditions. In the Cliff and Lorimer method, which was developed for the analytical transmission electron microscope, the composition was calculated from the ratio of the characteristic x-ray intensities of two elements in the same spectrum. In this work, this ratio method is applied to bulk specimens in a scanning electron microscope (SEM). In order to reduce the amplitude of error propagation, the proposed ratio for SEM quantitative microanalysis is the intensity of a x-ray divided by the sum of intensities of one or more characteristic lines of each of tire elements found in the specimen. Moreover, the calculated x-ray intensities are corrected for the effects of absorption, fluorescence and Coster-Kronig yields, and other physical factors normally considered in microbeam analysis. Uncertainties in physical parameters and models, clue to the lack of exhaustive measurements as well as their scattering, revealed by a disaggrement between the measured and calculated ratios, are minimized by the use of a calibration factor inserted into the ratio. This calibration factor is determined using a standard for a given element. It can be used as often as needed and allows for the correction of uncertainties in the x-ray detector efficiency. In order to quantify the specimen, the measured experimental ratio is compared to a simulated ratio with the appropriate calibration factor. The composition is interpolated from the theoretical ratio curves. Two methods of calculation of emitted x-ray intensity are proposed, by analytical calculations using the Pouchou and Pichoir model or by an in-house developed Monte Carlo simulation program. Two sets of National Bureau of Standards (NBS) microanalysis standard reference materials, AuCu (SRM 482) and AuAg (SRM 481), are used to validate this method. The comparison of calculated composition with the nominal one underlines the need for a beam-energy-dependent calibration factor, particularly because of ionization cross-section uncertainties. The use of high energy characteristic x-ray lines (above 5 keV) permits accuracy around 3% with a beam-energy-dependent calibration factor. The effects of beam energy, ionization cross-section models, mass-absorption coefficients and x-ray generation methods are compensated by the appropriate calibration factor. The change of the family of characteristic lines affects the accuracy. Finally, as in any quantitative microanalysis, the use of a filter to extract the characteristic intensity causes errors for low energy peaks. The analysis of the effect of calibration factors and mass-absorption coefficient enhances the need for refining the x-ray generation and emission parameters. The error propagation is less important than if using the classical Cliff and Lorimer method in a SEM. However, the use of appropriate calibration factors and pair of lines offers promising accuracy in almost any conditions. This method is independent of the beam current, which is the purpose of this work. Despite many uncertainties of physical parameters, this method offers an efficient and reliable alternative to quantitative x-ray microanalysis with any electron microscope. Although developed for a binary material, the method can be extended to heterogeneous, rough, multiple-component materials, inasmuch as it can be simulated with a Monte Carlo program or any other method that computes characteristic x-ray lines intensities.

Horny, Paula

119

Terawatt x-ray free-electron-laser optimization by transverse electron distribution shaping  

NASA Astrophysics Data System (ADS)

We study the dependence of the peak power of a 1.5 Å Terawatt (TW), tapered x-ray free-electron laser (FEL) on the transverse electron density distribution. Multidimensional optimization schemes for TW hard x-ray free-electron lasers are applied to the cases of transversely uniform and parabolic electron beam distributions and compared to a Gaussian distribution. The optimizations are performed for a 200 m undulator and a resonant wavelength of ?r=1.5 Å using the fully three-dimensional FEL particle code genesis. The study shows that the flatter transverse electron distributions enhance optical guiding in the tapered section of the undulator and increase the maximum radiation power from a maximum of 1.56 TW for a transversely Gaussian beam to 2.26 TW for the parabolic case and 2.63 TW for the uniform case. Spectral data also shows a 30%-70% reduction in energy deposited in the sidebands for the uniform and parabolic beams compared with a Gaussian. An analysis of the transverse coherence of the radiation shows the coherence area to be much larger than the beam spotsize for all three distributions, making coherent diffraction imaging experiments possible.

Emma, C.; Wu, J.; Fang, K.; Chen, S.; Serkez, S.; Pellegrini, C.

2014-11-01

120

Advances in X-Ray Chemical Analysis, Japan, 45 (2014) ISSN 0911-7806 Discharge Phenomena during X-Ray Emission from Pyroelectric Crystal  

E-print Network

Advances in X-Ray Chemical Analysis, Japan, 45 (2014) ISSN 0911-7806 © X X Discharge Phenomena during X-Ray Emission from Pyroelectric Crystal and Energy Dependence of X-Ray Intensity Kengo OHIRA, Susumu IMASHUKU and Jun KAWAI #12;#12;45 181 X X Adv. X-Ray. Chem. Anal., Japan 45, pp.181-190 (2014) 606

Jun, Kawai

121

Hard-X-ray magnetic microscopy and local magnetization analysis using synchrotron radiation.  

PubMed

X-ray measurement offers several useful features that are unavailable from other microscopic means including electron-based techniques. By using X-rays, one can observe the internal parts of a thick sample. This technique basically requires no high vacuum environment such that measurements are feasible for wet specimens as well as under strong electric and magnetic fields and even at a high pressure. X-ray spectroscopy using core excitation provides element-selectivity with significant sensitivities to the chemical states and atomic magnetic moments in the matter. Synchrotron radiation sources produce a small and low-divergent X-ray beam, which can be converged to a spot with the size of a micrometer or less using X-ray focusing optics. The recent development in the focusing optics has been driving X-ray microscopy, which has already gone into the era of X-ray nanoscopy. With the use of the most sophisticated focusing devices, an X-ray beam of 7-nm size has successfully been achieved [1]. X-ray microscopy maintains above-mentioned unique features of X-ray technique, being a perfect complement to electron microscopy.In this paper, we present recent studies on magnetic microscopy and local magnetic analysis using hard X-rays. The relevant instrumentation developments are also described. The X-ray nanospectroscopy station of BL39XU at SPring-8 is equipped with a focusing optics consisting of two elliptic mirrors, and a focused X-ray beam with the size of 100 × 100 nm(2) is available [2]. Researchers can perform X-ray absorption spectroscopy: nano-XAFS (X-ray absorption fine structure) using the X-ray beam as small as 100 nm. The available X-ray energy is from 5 to 16 keV, which allows nano-XAFS study at the K edges of 3d transition metals, L edges of rare-earth elements and 5d noble metals. Another useful capability of the nanoprobe is X-ray polarization tunability, enabling magnetic circular dichroism (XMCD) spectroscopy with a sub-micrometer resolution. Scanning XMCD imaging, XMCD measurement in local areas, and element-specific magnetometry for magnetic particles/magnetic devices as small as 100 nm can be performed. Nano-XAFS application includes visualization of the chemical state in a particle catalyst [3] and phase-change memory devices [4]. For magnetic microscopic study, magnetization reversal processes of an individual magnetic CoPt dot in bit-patterned media have directly been observed [2]. Imaging of the chemical distribution and magnetic domain evolution in a Nd-Fe-B sintered magnet in demagnetization processes is presented. PMID:25359804

Suzuki, Motohiro

2014-11-01

122

In Situ X-Ray Analysis of Protein Crystals in Low-Birefringent And X-Ray Transmissive Plastic Microchannels  

SciTech Connect

Plastic microchannel crystallization template designs made from inexpensive cyclic olefin copolymers have been shown to be low-birefringent, X-ray transmissive and compatible with microfluidic fabrication in restricted geometry. The model proteins thaumatin, lysozyme and bacteriorhodopsin demonstrated the feasibility of conducting counter-diffusion equilibration within the new plastic configuration. Crystals of each of these proteins were directly evaluated in situ using synchrotron radiation and their diffraction quality was evaluated without invasive manipulation or cryofreezing. Protein crystals able to produce complete X-ray data sets were used to calculate electron-density maps for structure determination. Fluidic crystallization in the plastic platform was also coupled with a commercialized automated imager and an in situ X-ray scanner that allowed optical and X-ray inspection of crystallization hits. The results demonstrate the feasibility of rapid nanovolume counter-diffusion crystallization experiments without the need for additional instrumentation.

Ng, J.D.; Clark, P.J.; Stevens, R.C.; Kuhn, P.

2009-05-22

123

Hard X rays of relativistic electrons accelerated in solar flares  

NASA Astrophysics Data System (ADS)

The direction and polarization degree of hard X rays (HXRs) in solar flares are studied. The continuous injection of relativistic electrons, which is implemented in powerful flares, is considered. The stationary relativistic kinetic equation is studied by using the method of expansion in terms of the Legendre polynomial and by integrating the equations for the expansion coefficients. The HXR characteristics are calculated using the bremsstrahlung relativistic cross-section for different angular and energetic electron distributions in the acceleration region. A high linear polarization degree of HXRs (˜35%) has been obtained for narrow (˜cos6?) beams of electrons with a soft spectrum (˜ E -6); the polarization degree decreases with increasing quanta energy, whereas the directivity of a high-energy emission increases. This effect is absent for a nonrelativistic approximation. The considered model is applied to one of the most powerful flares in cycle 23, registered on October 28, 2003. The measured polarization degree values at relativistic energies (0.2-0.4 and 0.4-1 MeV) agree with the results achieved in the considered model when the electron energy spectrum index (? = 2.5), angular distribution part (˜cos6?), and the spectrum cutoff energy ( E max = 1.3 MeV) were specified.

Kudryavtsev, I. V.; Charikov, Yu. E.

2012-12-01

124

Full spatial characterization of a nanofocused x-ray free-electron laser beam by ptychographic imaging  

PubMed Central

The emergence of hard X-ray free electron lasers (XFELs) enables new insights into many fields of science. These new sources provide short, highly intense, and coherent X-ray pulses. In a variety of scientific applications these pulses need to be strongly focused. In this article, we demonstrate focusing of hard X-ray FEL pulses to 125?nm using refractive x-ray optics. For a quantitative analysis of most experiments, the wave field or at least the intensity distribution illuminating the sample is needed. We report on the full characterization of a nanofocused XFEL beam by ptychographic imaging, giving access to the complex wave field in the nanofocus. From these data, we obtain the full caustic of the beam, identify the aberrations of the optic, and determine the wave field for individual pulses. This information is for example crucial for high-resolution imaging, creating matter in extreme conditions, and nonlinear x-ray optics. PMID:23567281

Schropp, Andreas; Hoppe, Robert; Meier, Vivienne; Patommel, Jens; Seiboth, Frank; Lee, Hae Ja; Nagler, Bob; Galtier, Eric C.; Arnold, Brice; Zastrau, Ulf; Hastings, Jerome B.; Nilsson, Daniel; Uhlén, Fredrik; Vogt, Ulrich; Hertz, Hans M.; Schroer, Christian G.

2013-01-01

125

Applications of parametric X-rays for X-ray diffraction analysis  

NASA Astrophysics Data System (ADS)

Until now parametric X-rays (PXR) have not had practical applications because of the lack of a modern compact accelerator providing the required beam current and consequently high X-ray photon flux. PXR sources even with the intensities achievable at present may be applied to a number of X-ray reflectometry and diffractometry measurements which are important for the characterization of crystals and multi-layer nanostructures. In the paper we present some proposals for possible PXR applications for a number of X-ray measurements based on the smooth energy tuning, high monochromaticity and directed emission of this radiation. The theoretical background and numerical evaluations for PXR applications for determining ingredient concentration in a solid solution in the range of anomalous dispersion of the defect atoms, determination of the phase structure of a crystal, and selective PXR action in organic compounds, important for medical and biological research, are considered.

Feranchuk, I. D.; Lobko, A. S.

2008-09-01

126

X-ray fluorescence/Auger-electron coincidence spectroscopy of vacancy cascades in atomic argon  

SciTech Connect

Argon L{sub 2.3}-M{sub 2.3}M{sub 2.3} Auger-electron spectra were measured in coincidence with K{alpha} fluorescent x-rays in studies of Ar K-shell vacancy decays at several photon energies above the K-threshold and on the 1s-4p resonance in atomic argon. The complex spectra recorded by conventional electron spectroscopy are greatly simplified when recorded in coincidence with fluorescent x-rays, allowing a more detailed analysis of the vacancy cascade process. The resulting coincidence spectra are compared with Hartree-Fock calculations which include shake-up transitions in the resonant case. Small energy shifts of the coincidence electron spectra are attributed to post-collision interaction with 1s photoelectrons.

Arp, U. [National Inst. of Standards and Technology, Gaithersburg, MD (United States). Electron and Optical Physics Div.; LeBrun, T.; Southworth, S.H.; Jung, M. [Argonne National Lab., IL (United States). Physics Div.; MacDonald, M.A. [E.P.S.R.C. Daresbury Lab., Warrington (United Kingdom)

1996-12-01

127

Few-femtosecond time-resolved measurements of X-ray free-electron lasers  

NASA Astrophysics Data System (ADS)

X-ray free-electron lasers, with pulse durations ranging from a few to several hundred femtoseconds, are uniquely suited for studying atomic, molecular, chemical and biological systems. Characterizing the temporal profiles of these femtosecond X-ray pulses that vary from shot to shot is not only challenging but also important for data interpretation. Here we report the time-resolved measurements of X-ray free-electron lasers by using an X-band radiofrequency transverse deflector at the Linac Coherent Light Source. We demonstrate this method to be a simple, non-invasive technique with a large dynamic range for single-shot electron and X-ray temporal characterization. A resolution of less than 1?fs root mean square has been achieved for soft X-ray pulses. The lasing evolution along the undulator has been studied with the electron trapping being observed as the X-ray peak power approaches 100?GW.

Behrens, C.; Decker, F.-J.; Ding, Y.; Dolgashev, V. A.; Frisch, J.; Huang, Z.; Krejcik, P.; Loos, H.; Lutman, A.; Maxwell, T. J.; Turner, J.; Wang, J.; Wang, M.-H.; Welch, J.; Wu, J.

2014-04-01

128

Few-femtosecond time-resolved measurements of X-ray free-electron lasers.  

PubMed

X-ray free-electron lasers, with pulse durations ranging from a few to several hundred femtoseconds, are uniquely suited for studying atomic, molecular, chemical and biological systems. Characterizing the temporal profiles of these femtosecond X-ray pulses that vary from shot to shot is not only challenging but also important for data interpretation. Here we report the time-resolved measurements of X-ray free-electron lasers by using an X-band radiofrequency transverse deflector at the Linac Coherent Light Source. We demonstrate this method to be a simple, non-invasive technique with a large dynamic range for single-shot electron and X-ray temporal characterization. A resolution of less than 1 fs root mean square has been achieved for soft X-ray pulses. The lasing evolution along the undulator has been studied with the electron trapping being observed as the X-ray peak power approaches 100 GW. PMID:24781868

Behrens, C; Decker, F-J; Ding, Y; Dolgashev, V A; Frisch, J; Huang, Z; Krejcik, P; Loos, H; Lutman, A; Maxwell, T J; Turner, J; Wang, J; Wang, M-H; Welch, J; Wu, J

2014-01-01

129

Numerical simulations of X-rays Free Electron Lasers (XFEL)  

E-print Network

We study a nonlinear Schr\\"odinger equation which arises as an effective single particle model in X-ray Free Electron Lasers (XFEL). This equation appears as a first-principles model for the beam-matter interactions that would take place in an XFEL molecular imaging experiment in \\cite{frat1}. Since XFEL is more powerful by several orders of magnitude than more conventional lasers, the systematic investigation of many of the standard assumptions and approximations has attracted increased attention. In this model the electrons move under a rapidly oscillating electromagnetic field, and the convergence of the problem to an effective time-averaged one is examined. We use an operator splitting pseudo-spectral method to investigate numerically the behaviour of the model versus its time-averaged version in complex situations, namely the energy subcritical/mass supercritical case, and in the presence of a periodic lattice. We find the time averaged model to be an effective approximation, even close to blowup, for fast enough oscillations of the external field. This work extends previous analytical results for simpler cases \\cite{xfel1}.

Paolo Antonelli; Agissilaos Athanassoulis; Zhongyi Huang; Peter A. Markowich

2014-06-17

130

Correlative analysis of hard and soft x ray observations of solar flares  

NASA Technical Reports Server (NTRS)

We have developed a promising new technique for jointly analyzing BATSE hard X-ray observations of solar flares with simultaneous soft X-ray observations. The technique is based upon a model in which electric currents and associated electric fields are responsible for the respective heating and particle acceleration that occur in solar flares. A useful by-product of this technique is the strength and evolution of the coronal electric field. The latter permits one to derive important flare parameters such as the current density, the number of current filaments composing the loop, and ultimately the hard X-ray spectrum produced by the runaway electrons. We are continuing to explore the technique by applying it to additional flares for which we have joint BATSE/Yohkoh observations. A central assumption of our analysis is the constant of proportionality alpha relating the hard X-ray flux above 50 keV and the rate of electron acceleration. For a thick-target model of hard X-ray production, it can be shown that cv is in fact related to the spectral index and low-energy cutoff of precipitating electrons. The next step in our analysis is to place observational constraints on the latter parameters using the joint BATSE/Yohkoh data.

Zarro, Dominic M.

1994-01-01

131

Accuracy evaluation of a Compton X-ray spectrometer with bremsstrahlung X-rays generated by a 6 MeV electron buncha)  

NASA Astrophysics Data System (ADS)

A Compton-scattering-based X-ray spectrometer is developed to obtain the energy distribution of fast electrons produced by intense laser and matter interactions. Bremsstrahlung X-rays generated by fast electrons in a material are used to measure fast electrons' energy distribution in matter. In the Compton X-ray spectrometer, X-rays are converted into recoil electrons by Compton scattering in a converter made from fused silica glass, and a magnet-based electron energy analyzer is used to measure the energy distribution of the electrons that recoil in the direction of the incident X-rays. The spectrum of the incident X-rays is reconstructed from the energy distribution of the recoil electrons. The accuracy of this spectrometer is evaluated using a quasi-monoenergetic 6 MeV electron bunch that emanates from a linear accelerator. An electron bunch is injected into a 1.5 mm thick tungsten plate to produce bremsstrahlung X-rays. The spectrum of these bremsstrahlung X-rays is obtained in the range from 1 to 9 MeV. The energy of the electrons in the bunch is estimated using a Monte Carlo simulation of particle-matter interactions. The result shows that the spectrometer's energy accuracy is ±0.5 MeV for 6.0 MeV electrons.

Kojima, Sadaoki; Arikawa, Yasunobu; Nishimura, Yasuhiko; Togawa, Hiromi; Zhang, Zhe; Ikenouchi, Takahito; Ozaki, Tetsuo; Morace, Alessio; Nagai, Takahiro; Abe, Yuki; Sakata, Shouhei; Inoue, Hiroaki; Utsugi, Masaru; Nakai, Mitsuo; Nishimura, Hiroaki; Shiraga, Hiroyuki; Kato, Ryukou; Fujioka, Shinsuke; Azechi, Hiroshi

2014-11-01

132

Feasibility considerations of a soft-x-ray distributed feedback laser pumped by an x-ray free electron laser  

E-print Network

We discuss the feasibility of a soft-x-ray distributed feedback laser (DFL) pumped by an x-ray free electron laser (X-FEL). The DFL under consideration is a Mg/SiC bi-layered Bragg reflector pumped by a single X-FEL bunch at 57.4 eV, stimulating the Mg L2,3 emission at 49 eV corresponding to the 3s-3d â??2p1/2,3/2 transition. Based on a model developed by Yariv and Yeh and an extended coupled-wave theory, we show that it would be possible to obtain a threshold gain compatible with the pumping provided by available X-FEL facilities.

André, Jean-Michel; Jonnard, Philippe

2014-01-01

133

A technique for calibrating an electron-beam evaporator x-ray source  

Microsoft Academic Search

An electron-beam metal evaporator was modified to act as an x-ray source for simulating x-ray lithography induced radiation\\u000a damage in semiconductor devices. Besides x-rays, such a set-up generates secondary and backscattered electrons. Simulation\\u000a of radiation damage induced during a typical x-ray lithography processing step requires that secondary and backscattered electrons\\u000a be removed from the incident radiation. A common method to

Robert J. Kinzig

1991-01-01

134

Hydrothermal synthesis of kaolinite illustrated by X-ray diffractograms and scanning electron micrographs, part II  

Microsoft Academic Search

Summary The hydrothermal synthesis of kaolinite from various alumina and silica starting materials reacted at 200°C in aqueous solutions of oxalic acid and H2SO4 with the corresponding saturated water vapour pressure, in periods of time from 10 to 25 days, has been followed by X-ray diffraction measurements, scanning electron microscopy, and energy dispersive analysis of the products. The temperature and

O. Lahodny-Sarc; D. Dosen-Sver; W. D. Keller

1984-01-01

135

Repair of fractured framework: scanning electron microscopy and energy dispersive X-ray spectroscopy.  

PubMed

Fractured metal prostheses can be analyzed for possible causes of failure using scanning electron microscopy (SEM). In this study, fractography is used to determine the cause of the failure and whether repair is practical. Energy-dispersive x-ray spectroscopy (EDS) is used to determine composition of the fractured prosthesis so that a repair process can be recommended. The technique is presented for the repair of a titanium framework for an implant-supported overdenture based on the analysis data. PMID:15359153

Maalhagh-Fard, Ahmad; Wagner, Warren C

2004-09-01

136

X-Ray Absorption Analysis By Image Processing Techniques  

NASA Astrophysics Data System (ADS)

A combination of an X-ray absorption instrument and an image processing system is described and data on cigarette densities are presented. Using an electro-mechanically controlled positioning unit the automatic analysis of samples larger than the sensor area is possible by sequential imaging storage. The final analysis of the image of the total object results in characteristic functions and parameters which can be related statistically to material specific measurements. This procedure is illustrated with a cigarette tobacco rod.

Trinkies, Wolfgang; Muller, Bernd-H.; Wiethaup, Wolfgang

1989-03-01

137

Intravenous coronary angiography utilizing K-emission and bremsstrahlung X-rays produced by electron bombardment  

SciTech Connect

The screening of the general population for coronary artery disease would be practical if a method existed for visualizing the extent of occlusion after an intravenous injection of contrast agent. Measurements performed with synchrotron radiation at SSRL and NSLS have shown that such an intravenous angiography procedure would be possible with an intense source of monochromatic X-rays. Because of the high cost of an electron synchrotron, theoretical analysis and experiments using inanimate phantoms has been undertaken to demonstrate the feasibility of using the spectrum produced by two appropriately chosen anode materials when bombarded with electrons in the 100--500 keV energy range for angiography. By using the X-rays emitted at 120{degree} to the incident electron direction, about 20--30% of the X-ray intensity would be due to K-emission lines. Calculations using the TIGERP Monte Carlo Code, have shown that high quality angiograms of human coronary arteries should be possible with a contrast agent containing ytterbium, if an electron beam pulses of 16 kJ were used for each anode target. The experimental program supported in part by the DOE has consisted of these theoretical calculations and experiments at the Dynamitron Electron Accelerator Facility at BNL.

NONE

1992-12-31

138

The amorphous Zn biomineralization at Naracauli stream, Sardinia: electron microscopy and X-ray absorption spectroscopy.  

PubMed

An amorphous Zn biomineralization ("white mud"), occurring at Naracauli stream, Sardinia, in association with cyanobacteria Leptolyngbya frigida and diatoms, was investigated by electron microscopy and X-ray absorption spectroscopy. Preliminary diffraction analysis shows that the precipitate sampled on Naracauli stream bed is mainly amorphous, with some peaks ascribable to quartz and phyllosilicates, plus few minor unattributed peaks. Scanning electron microscopy analysis shows that the white mud, precipitated in association with a seasonal biofilm, is made of sheaths rich in Zn, Si, and O, plus filaments likely made of organic matter. Transmission electron microscopy analysis shows that the sheaths are made of smaller units having a size in the range between 100 and 200 nm. X-ray absorption near-edge structure and extended X-ray absorption fine structure data collected at the Zn K-edge indicate that the biomineral has a local structure similar to hemimorphite, a zinc sorosilicate. The differences of this biomineral with respect to the hydrozincite biomineralization documented about 3 km upstream in the same Naracauli stream may be related to either variations in the physicochemical parameters and/or different metabolic behavior of the involved biota. PMID:23832800

Medas, D; Lattanzi, P; Podda, F; Meneghini, C; Trapananti, A; Sprocati, A; Casu, M A; Musu, E; De Giudici, G

2014-06-01

139

Depth analysis of subgap electronic states in amorphous oxide semiconductor, a-In-Ga-Zn-O, studied by hard x-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

In a previous work, we examined subgap states in highly doped amorphous In-Ga-Zn-O (a-IGZO) films by hard x-ray photoelectron spectroscopy (HX-PES) and found they had subgap electronic states above the valence band maximum (VBM) with the densities > 5 × 1020 cm-3 and just below the Fermi level with the densities > 5 × 1019 cm-3 [K. Nomura, T. Kamiya, H. Yanagi, E. Ikenaga, K. Yang, K. Kobayashi, M. Hirano, and H. Hosono, Appl. Phys. Lett. 92, 202117 (2008)]; however, their electron densities (Ne > 3 × 1019 cm-3) are rather high and not compatible with rational properties required for active channel layers in thin-film transistors (TFTs). In this work, we report the effects of Ne and thermal annealing on the subgap states in order to provide the data useful for actual TFTs. It was found that the low-Ne a-IGZO films had extra subgap states above VBM similar to the previous report, but their densities were as small as ˜2.0 × 1020 cm-3 for the highly resistive, wet-annealed a-IGZO films. Angle-dependent HX-PES revealed that the subgap states above VBM concentrate in the surface region. The O 1s peak indicated that the wet annealing suppressed the generation of subgap states by terminating these states with -OH bonds. The subgap states below EF were observed commonly in all the samples including ZnO, crystalline (c-) IGZO and a-IGZO. It is concluded that these states below EF are neither related to the disordered structures of a-IGZO nor to their TFT characteristics. It is considered that these states are related to the metastable states created by the high-energy photons in vacuum.

Nomura, Kenji; Kamiya, Toshio; Ikenaga, Eiji; Yanagi, Hiroshi; Kobayashi, Keisuke; Hosono, Hideo

2011-04-01

140

Microscale reconstruction of biogeochemical substrates using multimode X-ray tomography and scanning electron microscopy  

NASA Astrophysics Data System (ADS)

X-ray computed tomography (CT), scanning electron microscopy (SEM), electron microprobe analysis (EMP), and computational image analysis are mature technologies used in many disciplines. Cross-discipline combination of these imaging and image-analysis technologies is the focus of this research, which uses laboratory and light-source resources in an iterative approach. The objective is to produce images across length scales, taking advantage of instrumentation that is optimized for each scale, and to unify them into a single compositional reconstruction. Initially, CT images will be collected using both x-ray absorption and differential phase contrast modes. The imaged sample will then be physically sectioned and the exposed surfaces imaged and characterized via SEM/EMP. The voxel slice corresponding to the physical sample surface will be isolated computationally, and the volumetric data will be combined with two-dimensional SEM images along CT image planes. This registration step will take advantage of the similarity between the X-ray absorption (CT) and backscattered electron (SEM) coefficients (both proportional to average atomic number in the interrogated volume) as well as the images' mutual information. Elemental and solid-phase distributions on the exposed surfaces, co-registered with SEM images, will be mapped using EMP. The solid-phase distribution will be propagated into three-dimensional space using computational methods relying on the estimation of compositional distributions derived from the CT data. If necessary, solid-phase and pore-space boundaries will be resolved using X-ray differential phase contrast tomography, x-ray fluorescence tomography, and absorption-edge microtomography at a light-source facility. Computational methods will be developed to register and model images collected over varying scales and data types. Image resolution, physically and dynamically, is qualitatively different for the electron microscopy and CT methodologies. Routine CT images are resolved at 10-20 ?m, while SEM images are resolved at 10-20 nm; grayscale values vary according to collection time and instrument sensitivity; and compositional sensitivities via EMP vary in interrogation volume and scale. We have so far successfully registered SEM imagery within a multimode tomographic volume and have used standard methods to isolate pore space within the volume. We are developing a three-dimensional solid-phase identification and registration method that is constrained by bulk-sample X-ray diffraction Rietveld refinements. The results of this project will prove useful in fields that require the fine-scale definition of solid-phase distributions and relationships, and could replace more inefficient methods for making these estimations.

Miller, M.; Miller, E.; Liu, J.; Lund, R. M.; McKinley, J. P.

2012-12-01

141

Comparison of Extended X-ray Absorption Fine Structure and Scherrer Analysis of X-ray Diffraction as Methods for Determining Mean Sizes of Polydisperse Nanoparticles  

SciTech Connect

Curve fitting of extended x-ray absorption fine structure (EXAFS) spectra, transmission electron microscopy (TEM) imaging, and Scherrer analysis of x-ray diffraction (XRD) are compared as methods for determining the mean crystallite size in polydisperse samples of platinum nanoparticles. By applying the techniques to mixtures of pure samples, it is found that EXAFS correctly determines the relative mean sizes of these polydisperse samples, while XRD tends to be weighted more toward the largest crystallites in the sample. Results for TEM are not clear cut, due to polycrystallinity and aggregation, but are consistent with the other results.

Calvin,S.; Luo, S.; Caragianis-Broadbridge, C.; McGuinness, J.; Anderson, E.; Lehman, A.; Wee, K.; Morrison, S.; Kurihara, L.

2005-01-01

142

Macromolecular structures probed by combining single-shot free-electron laser diffraction with synchrotron coherent X-ray imaging.  

PubMed

Nanostructures formed from biological macromolecular complexes utilizing the self-assembly properties of smaller building blocks such as DNA and RNA hold promise for many applications, including sensing and drug delivery. New tools are required for their structural characterization. Intense, femtosecond X-ray pulses from X-ray free-electron lasers enable single-shot imaging allowing for instantaneous views of nanostructures at ambient temperatures. When combined judiciously with synchrotron X-rays of a complimentary nature, suitable for observing steady-state features, it is possible to perform ab initio structural investigation. Here we demonstrate a successful combination of femtosecond X-ray single-shot diffraction with an X-ray free-electron laser and coherent diffraction imaging with synchrotron X-rays to provide an insight into the nanostructure formation of a biological macromolecular complex: RNA interference microsponges. This newly introduced multimodal analysis with coherent X-rays can be applied to unveil nano-scale structural motifs from functional nanomaterials or biological nanocomplexes, without requiring a priori knowledge. PMID:24786694

Gallagher-Jones, Marcus; Bessho, Yoshitaka; Kim, Sunam; Park, Jaehyun; Kim, Sangsoo; Nam, Daewoong; Kim, Chan; Kim, Yoonhee; Noh, Do Young; Miyashita, Osamu; Tama, Florence; Joti, Yasumasa; Kameshima, Takashi; Hatsui, Takaki; Tono, Kensuke; Kohmura, Yoshiki; Yabashi, Makina; Hasnain, S Samar; Ishikawa, Tetsuya; Song, Changyong

2014-01-01

143

Macromolecular structures probed by combining single-shot free-electron laser diffraction with synchrotron coherent X-ray imaging  

NASA Astrophysics Data System (ADS)

Nanostructures formed from biological macromolecular complexes utilizing the self-assembly properties of smaller building blocks such as DNA and RNA hold promise for many applications, including sensing and drug delivery. New tools are required for their structural characterization. Intense, femtosecond X-ray pulses from X-ray free-electron lasers enable single-shot imaging allowing for instantaneous views of nanostructures at ambient temperatures. When combined judiciously with synchrotron X-rays of a complimentary nature, suitable for observing steady-state features, it is possible to perform ab initio structural investigation. Here we demonstrate a successful combination of femtosecond X-ray single-shot diffraction with an X-ray free-electron laser and coherent diffraction imaging with synchrotron X-rays to provide an insight into the nanostructure formation of a biological macromolecular complex: RNA interference microsponges. This newly introduced multimodal analysis with coherent X-rays can be applied to unveil nano-scale structural motifs from functional nanomaterials or biological nanocomplexes, without requiring a priori knowledge.

Gallagher-Jones, Marcus; Bessho, Yoshitaka; Kim, Sunam; Park, Jaehyun; Kim, Sangsoo; Nam, Daewoong; Kim, Chan; Kim, Yoonhee; Noh, Do Young; Miyashita, Osamu; Tama, Florence; Joti, Yasumasa; Kameshima, Takashi; Hatsui, Takaki; Tono, Kensuke; Kohmura, Yoshiki; Yabashi, Makina; Hasnain, S. Samar; Ishikawa, Tetsuya; Song, Changyong

2014-05-01

144

X-ray emission from relativistically moving electron density cusps  

SciTech Connect

We report on novel methods to generate ultra-short, coherent, X-rays using a laserplasma interaction. Nonlinear interaction of intense laser pulses with plasma creates stable, specific structures such as electron cusps. For example, wake waves excited in an underdense plasma by an intense, short-pulse laser become dense and propagate along with the laser pulse. This is called a relativistic flying mirror. The flying mirror can reflect a counter-propagating laser pulse and directly convert it into high-frequency radiation, with a frequency multiplication factor of {approx} 4{gamma}{sup 2} and pulse shortening with the same factor. After the proof-of-principle experiments, we observed that the photon number generated in the flying mirror is close to the theoretical estimate. We present the details of the experiment in which a 9 TW laser pulse focused into a He gas jet generated the Flying Mirror, which partly reflected a 1 TW pulse, giving up to {approx} 10{sup 10} photons, 60 nJ (1.4 Multiplication-Sign 10{sup 12} photons/sr) in the XUV spectral region (12.8-22 nm).

Kando, M.; Pirozhkov, A. S.; Nakamura, T.; Hayashi, Y.; Kotaki, H.; Kawase, K.; Esirkepov, T. Zh.; Fukuda, Y.; Kiriyama, H.; Okada, H.; Daito, I.; Kameshima, T.; Mori, M.; Koga, J. K.; Daido, H.; Faenov, A. Ya.; Pikuz, T.; Ma, J.; Chen, L.-M.; Ragozin, E. N. [Japan Atomic Energy Agency (Japan); Osaka University (Japan); Joint Institute for High Temperature of the Russian Academy of Science, Moscow (Russian Federation); Institute of Physics, Chinese Academy of Sciences, Beijing (China); P. N. Lebedev Physical Institute of the Russian Academy of Sciences, Leninsky prospekt 53, 119991 Moscow (Russian Federation); Japan Atomic Energy Agency and Graduate School for the Creation of New Photonics Industries (Japan); Ludwig-Maximilians-University (Germany); and others

2012-07-11

145

X-ray emission from relativistically moving electron density cusps  

NASA Astrophysics Data System (ADS)

We report on novel methods to generate ultra-short, coherent, X-rays using a laserplasma interaction. Nonlinear interaction of intense laser pulses with plasma creates stable, specific structures such as electron cusps. For example, wake waves excited in an underdense plasma by an intense, short-pulse laser become dense and propagate along with the laser pulse. This is called a relativistic flying mirror. The flying mirror can reflect a counter-propagating laser pulse and directly convert it into high-frequency radiation, with a frequency multiplication factor of ˜ 4?2 and pulse shortening with the same factor. After the proof-of-principle experiments, we observed that the photon number generated in the flying mirror is close to the theoretical estimate. We present the details of the experiment in which a 9 TW laser pulse focused into a He gas jet generated the Flying Mirror, which partly reflected a 1 TW pulse, giving up to ˜ 1010 photons, 60 nJ (1.4×1012 photons/sr) in the XUV spectral region (12.8-22 nm).

Kando, M.; Pirozhkov, A. S.; Nakamura, T.; Hayashi, Y.; Kotaki, H.; Kawase, K.; Esirkepov, T. Zh.; Fukuda, Y.; Kiriyama, H.; Okada, H.; Daito, I.; Kameshima, T.; Mori, M.; Koga, J. K.; Daido, H.; Faenov, A. Ya.; Pikuz, T.; Ma, J.; Chen, L.-M.; Ragozin, E. N.; Kawachi, T.; Kato, Y.; Tajima, T.; Bulanov, S. V.

2012-07-01

146

Nuclear Resonance Energy Analysis of Inelastic X-Ray Scattering  

Microsoft Academic Search

Inelastic scattering of x rays by gaseous, liquid, and solid samples was measured using a nuclear transition as a reference for the energy analysis of the scattered radiation. The samples were irradiated by a beam of synchrotron radiation with a bandwidth of 6.4 meV. The scattered radiation was analyzed using a resonance detector with a bandpass of 0.5 mueV. These

A. I. Chumakov; A. Q. R. Baron; R. Rüffer; H. Grünsteudel; A. Meyer

1996-01-01

147

In situ X-ray Photoelectron, Ultraviolet Photoelectron, and Auger Electron  

E-print Network

In situ X-ray Photoelectron, Ultraviolet Photoelectron, and Auger Electron Spectroscopy Spectra at Urbana-Champaign, Urbana, IL 61801 X-ray photoelectron XPS , ultraviolet photoelectron UPS , and Auger electron spectroscopy AES spectra are presented from epitaxial, single-crystal transition-metal TM nitride

Gall, Daniel

148

Probing electronic structure and chemical bonding with x-ray spectroscopy  

Microsoft Academic Search

The availability of synchrotron sources has expanded significantly the use of x-ray photoelectron (PE) and photoabsorption (PA) spectroscopy to probe the molecular electronic structure and to test the various bonding models the understanding of which is central to all aspects of chemistry. All features observed in x-ray spectra result from electronic transitions within the molecule, which are in turn determined

Astrid Jurgensen

1999-01-01

149

Neutron and X-ray Scattering Studies of Strongly Correlated Electron Systems  

E-print Network

Neutron and X-ray Scattering Studies of Strongly Correlated Electron Systems Russell A. Ewings 2008 #12;Abstract Neutron and X-ray Scattering Studies of Strongly Correlated Electron Systems Russell-ray scattering and neutron scattering experiments on several strongly correlated transition metal oxides

Boothroyd, Andrew

150

Is scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS) quantitative?  

PubMed

Scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS) is a widely applied elemental microanalysis method capable of identifying and quantifying all elements in the periodic table except H, He, and Li. By following the "k-ratio" (unknown/standard) measurement protocol development for electron-excited wavelength dispersive spectrometry (WDS), SEM/EDS can achieve accuracy and precision equivalent to WDS and at substantially lower electron dose, even when severe X-ray peak overlaps occur, provided sufficient counts are recorded. Achieving this level of performance is now much more practical with the advent of the high-throughput silicon drift detector energy dispersive X-ray spectrometer (SDD-EDS). However, three measurement issues continue to diminish the impact of SEM/EDS: (1) In the qualitative analysis (i.e., element identification) that must precede quantitative analysis, at least some current and many legacy software systems are vulnerable to occasional misidentification of major constituent peaks, with the frequency of misidentifications rising significantly for minor and trace constituents. (2) The use of standardless analysis, which is subject to much broader systematic errors, leads to quantitative results that, while useful, do not have sufficient accuracy to solve critical problems, e.g. determining the formula of a compound. (3) EDS spectrometers have such a large volume of acceptance that apparently credible spectra can be obtained from specimens with complex topography that introduce uncontrolled geometric factors that modify X-ray generation and propagation, resulting in very large systematic errors, often a factor of ten or more. PMID:22886950

Newbury, Dale E; Ritchie, Nicholas W M

2013-01-01

151

Scanning electron microscopy and electron probe X-ray microanalysis (SEM-EPMA) of pink teeth  

SciTech Connect

Samples of postmortem pink teeth were investigated by scanning electron microscopy and electron probe X-ray microanalysis. Fracture surfaces of the dentin in pink teeth were noticeably rough and revealed many more smaller dentinal tubules than those of the control white teeth. Electron probe X-ray microanalysis showed that the pink teeth contained iron which seemed to be derived from blood hemoglobin. The present study confirms that under the same circumstance red coloration of teeth may occur more easily in the teeth in which the dentin is less compact and contains more dentinal tubules.

Ikeda, N.; Watanabe, G.; Harada, A.; Suzuki, T.

1988-11-01

152

X-ray spectroscopic study of the electronic structure of CuCrO2  

Microsoft Academic Search

The electronic structure of the p -type transparent conducting oxide CuCrO2 has been studied by x-ray photoemission, x-ray absorption, and x-ray emission spectroscopies. The upper part of the valence band derives mainly from Cu3d and Cr3d states while the lower valence-band states are of dominant O2p atomic character, but with pronounced mutual hybridization among Cu3d , Cr3d , and O2p

T. Arnold; D. J. Payne; A. Bourlange; J. P. Hu; R. G. Egdell; L. F. J. Piper; L. Colakerol; A. de Masi; P.-A. Glans; T. Learmonth; K. E. Smith; J. Guo; D. O. Scanlon; A. Walsh; B. J. Morgan; G. W. Watson

2009-01-01

153

X-ray transitions for studying the electronic structure of 5d metals  

SciTech Connect

X-ray fluorescence transitions of the type 5d{yields}4p have been measured for the 5d compounds Ta, TaC, and Ta{sub 2}O{sub 5}. The measured Ta N{sub 3} x-ray emission spectra are compared with band-structure calculations and it is concluded that the soft-x-ray transitions can be used to study occupied 5d electronic states in materials with 5d elements.

Kurmaev, E. Z.; Moewes, A.; Pchelkina, Z. V.; Nekrasov, I. A.; Rempel, A. A.; Ederer, D. L.

2001-08-15

154

Fluctuation analysis of stellar x-ray binary systems  

NASA Astrophysics Data System (ADS)

We study time series of x-ray sources of 129 stellar binary systems present in the public data collected by the instrument All Sky Monitor on board of the satellite Rossi X-Ray Timing Explorer. The light time series was analyzed by applying detrended fluctuation analysis to estimate the long-range power-law correlation exponents ?. The scaling exponent was calculated for all systems and its value indicated a signature of each kind of system, i.e., whether flare takes place (with ?=1.22) or not (with ?=0.64). As a consequence, our results may identify the stability of the systems from the scaling exponent ? value, for instance, if ?˜0.5 (white noise) the system is stable and unstable when ??0.5 (long-range power-law correlation).

Moret, M. A.; Zebende, G. F.; Nogueira, E.; Pereira, M. G.

2003-10-01

155

Design and analysis of multilayer x ray/XUV microscope  

NASA Technical Reports Server (NTRS)

The design and analysis of a large number of normal incidence multilayer x ray microscopes based on the spherical mirror Schwarzschild configuration is examined. Design equations for the spherical mirror Schwarzschild microscopes are summarized and used to evaluate mirror parameters for microscopes with magnifications ranging from 2 to 50x. Ray tracing and diffraction analyses are carried out for many microscope configurations to determine image resolution as a function of system parameters. The results are summarized in three publication included herein. A preliminary study of advanced reflecting microscope configurations, where aspherics are used in place of the spherical microscope mirror elements, has indicated that the aspherical elements will improve off-axis image resolution and increase the effective field of view.

Shealy, David L.

1990-01-01

156

Reabsorption of soft x-ray emission at high x-ray free-electron laser fluences.  

PubMed

We report on oxygen K-edge soft x-ray emission spectroscopy from a liquid water jet at the Linac Coherent Light Source. We observe significant changes in the spectral content when tuning over a wide range of incident x-ray fluences. In addition the total emission yield decreases at high fluences. These modifications result from reabsorption of x-ray emission by valence-excited molecules generated by the Auger cascade. Our observations have major implications for future x-ray emission studies at intense x-ray sources. We highlight the importance of the x-ray pulse length with respect to the core-hole lifetime. PMID:25375708

Schreck, Simon; Beye, Martin; Sellberg, Jonas A; McQueen, Trevor; Laksmono, Hartawan; Kennedy, Brian; Eckert, Sebastian; Schlesinger, Daniel; Nordlund, Dennis; Ogasawara, Hirohito; Sierra, Raymond G; Segtnan, Vegard H; Kubicek, Katharina; Schlotter, William F; Dakovski, Georgi L; Moeller, Stefan P; Bergmann, Uwe; Techert, Simone; Pettersson, Lars G M; Wernet, Philippe; Bogan, Michael J; Harada, Yoshihisa; Nilsson, Anders; Föhlisch, Alexander

2014-10-10

157

Reabsorption of Soft X-Ray Emission at High X-Ray Free-Electron Laser Fluences  

NASA Astrophysics Data System (ADS)

We report on oxygen K-edge soft x-ray emission spectroscopy from a liquid water jet at the Linac Coherent Light Source. We observe significant changes in the spectral content when tuning over a wide range of incident x-ray fluences. In addition the total emission yield decreases at high fluences. These modifications result from reabsorption of x-ray emission by valence-excited molecules generated by the Auger cascade. Our observations have major implications for future x-ray emission studies at intense x-ray sources. We highlight the importance of the x-ray pulse length with respect to the core-hole lifetime.

Schreck, Simon; Beye, Martin; Sellberg, Jonas A.; McQueen, Trevor; Laksmono, Hartawan; Kennedy, Brian; Eckert, Sebastian; Schlesinger, Daniel; Nordlund, Dennis; Ogasawara, Hirohito; Sierra, Raymond G.; Segtnan, Vegard H.; Kubicek, Katharina; Schlotter, William F.; Dakovski, Georgi L.; Moeller, Stefan P.; Bergmann, Uwe; Techert, Simone; Pettersson, Lars G. M.; Wernet, Philippe; Bogan, Michael J.; Harada, Yoshihisa; Nilsson, Anders; Föhlisch, Alexander

2014-10-01

158

Phase stabilization in cinnarizine complexes using X-ray profile analysis  

NASA Astrophysics Data System (ADS)

Characterization of cobalt(II), cadmium(II), copper(II) and tin(II) cinnarizine complexes have been carried out using conductivity, electronic spectra, infrared, nmr, thermogravimetric and X-ray analyses to establish the nature of phase stabilization in these materials. Also, the intrinsic strain components present in these materials during the formation have been computed using wide-angle X-ray scattering analysis. The variation of the crystallite shape ellipsoid in these materials has been discussed on the basis of Hosemann's paracrystalline model.

Nagendrappa, G.; Urs, S. Subramanya Raj; Madhava, M. S.; Somashekar, R.

2001-06-01

159

X-ray source assembly having enhanced output stability, and fluid stream analysis applications thereof  

DOEpatents

An x-ray source assembly and method of operation are provided having enhanced output stability. The assembly includes an anode having a source spot upon which electrons impinge and a control system for controlling position of the anode source spot relative to an output structure. The control system can maintain the anode source spot location relative to the output structure notwithstanding a change in one or more operating conditions of the x-ray source assembly. One aspect of the disclosed invention is most amenable to the analysis of sulfur in petroleum-based fuels.

Radley, Ian (Glenmont, NY); Bievenue, Thomas J. (Delmar, NY); Burdett, John H. (Charlton, NY); Gallagher, Brian W. (Guilderland, NY); Shakshober, Stuart M. (Hudson, NY); Chen, Zewu (Schenectady, NY); Moore, Michael D. (Alplaus, NY)

2008-06-08

160

Laboratory-size three-dimensional x-ray microscope with Wolter type I mirror optics and an electron-impact water window x-ray source  

NASA Astrophysics Data System (ADS)

We constructed a laboratory-size three-dimensional water window x-ray microscope that combines wide-field transmission x-ray microscopy with tomographic reconstruction techniques, and observed bio-medical samples to evaluate its applicability to life science research fields. It consists of a condenser and an objective grazing incidence Wolter type I mirror, an electron-impact type oxygen K? x-ray source, and a back-illuminated CCD for x-ray imaging. A spatial resolution limit of around 1.0 line pairs per micrometer was obtained for two-dimensional transmission images, and 1-?m scale three-dimensional fine structures were resolved.

Ohsuka, Shinji; Ohba, Akira; Onoda, Shinobu; Nakamoto, Katsuhiro; Nakano, Tomoyasu; Miyoshi, Motosuke; Soda, Keita; Hamakubo, Takao

2014-09-01

161

The First Angstrom X-Ray Free-Electron Laser  

SciTech Connect

The Linac Coherent Light Source produced its first x-ray laser beam on 10 April 2009. Today it is routinely producing x-ray pulses with energy >2 mJ across the operating range from 820-8,200 eV. The facility has begun operating for atomic/molecular/optical science experiments. Performance of the facility in its first user run (1 October - 21 December) and current machine development activities will be presented. Early results from the preparations for the start of the second user run is also reported.

Galayda, John; /SLAC

2012-08-24

162

X-Ray-Diffraction Tests Of Irradiated Electronic Devices: I  

NASA Technical Reports Server (NTRS)

X-ray-diffraction tests performed on aluminum conductors in commercial HI1-507A complementary metal oxide/semiconductor (CMOS) integrated-circuit analog multiplexers, both before and after circuits exposed to ionizing radiation from Co(60) source, and after postirradiation annealing at ambient and elevated temperatures. Tests in addition to electrical tests performed to determine effects of irradiation and of postirradiation annealing on electrical operating characteristics of circuits. Investigators sought to determine whether relationship between effects of irradiation on devices and physical stresses within devices. X-ray diffraction potentially useful for nondestructive measurement of stresses.

Shaw, David C.; Lowry, Lynn E.; Barnes, Charles E.

1993-01-01

163

Harmonic lasing of x-ray free electron laser: on the way to smaller and cheaper  

E-print Network

By utilizing higher harmonics of undulator radiation, harmonic lasing is helpful in the development of compact x-ray free electron lasers (FELs), i.e. reducing its costs and sizes. Harmonic lasing of FELs have been experimentally demonstrated in the low-gain FEL oscillators from terahertz, infrared to ultraviolet spectral range. Based on the current status and future directions of short-wavelength FELs in the worldwide, this paper reviews the progresses on harmonic lasing of x-ray FELs, mainly concentrating on the recently proposed harmonic lasing of x-ray FEL oscillators and further ideas on harmonic lasing of single pass x-ray FEL amplifiers.

Deng, Haixiao

2012-01-01

164

Enabling membrane protein structure and dynamics with X-ray free electron lasers.  

PubMed

Determining the three-dimensional structures and dynamics of membrane proteins remains one of the great challenges of modern biology. The recent availability of X-ray free electron laser (XFEL) light sources has opened the door to a new and revolutionary approach to performing X-ray analysis of these important biomolecules. Recent advances in sample delivery, data reduction, and phasing have enabled the high-resolution structural probing of membrane proteins at room temperature. While considerable challenges remain, the recent developments described in this review may ultimately provide structural biologists with powerful tools for obtaining unprecedented atomic-scale and dynamic visualization of membrane proteins at near-physiological conditions. PMID:24930119

Feld, Geoffrey K; Frank, Matthias

2014-08-01

165

Three-dimensional manipulation of electron beam phase space for seeding soft x-ray free-electron lasers  

NASA Astrophysics Data System (ADS)

In this paper, a simple technique is proposed to induce strong density modulation into the electron beam with small energy modulation. By using the combination of a transversely dispersed electron beam and a wave-front tilted seed laser, three-dimensional manipulation of the electron beam phase space can be utilized to significantly enhance the microbunching of seeded free-electron laser schemes, which will improve the performance and extend the short-wavelength range of a single-stage seeded free-electron laser. Theoretical analysis and numerical simulations demonstrate the capability of the proposed technique in a soft x-ray free-electron laser.

Feng, Chao; Zhang, Tong; Deng, Haixiao; Zhao, Zhentang

2014-07-01

166

Three-dimensional manipulation of electron beam phase space for seeding soft x-ray free-electron lasers  

E-print Network

In this letter, a simple technique is proposed to induce strong density modulation into the electron beam with small energy modulation. By using the combination of a transversely dispersed electron beam and a wave-front tilted seed laser, three-dimensional manipulation of the electron beam phase space can be utilized to significantly enhance the micro-bunching of seeded free-electron laser schemes, which will improve the performance and extend the short-wavelength range of a single-stage seeded free-electron laser. Theoretical analysis and numerical simulations demonstrate the capability of the proposed technique in a soft x-ray free-electron laser.

Feng, Chao; Deng, Haixiao; Zhao, Zhentang

2014-01-01

167

Advances in X-Ray Chemical Analysis, Japan, 41 (2010) ISSN 0911-7806 Portable Total Reflection X-Ray Fluorescence Spectrometer  

E-print Network

Advances in X-Ray Chemical Analysis, Japan, 41 (2010) ISSN 0911-7806 © X Portable Total Reflection X-Ray Fluorescence Spectrometer for Ultra Trace Elemental Determination Shinsuke KUNIMURA and Jun KAWAI #12;#12;41 29 X Adv. X-Ray. Chem. Anal., Japan 41, pp.29-44 (2010) 606-8501 X Portable Total

Jun, Kawai

168

X-Ray Microanalysis and Electron Energy Loss Spectrometry in the Analytical Electron Microscope: Review and Future Directions  

NASA Technical Reports Server (NTRS)

This paper reviews and discusses future directions in analytical electron microscopy for microchemical analysis using X-ray and Electron Energy Loss Spectroscopy (EELS). The technique of X-ray microanalysis, using the ratio method and k(sub AB) factors, is outlined. The X-ray absorption correction is the major barrier to the objective of obtaining I% accuracy and precision in analysis. Spatial resolution and Minimum Detectability Limits (MDL) are considered with present limitations of spatial resolution in the 2 to 3 microns range and of MDL in the 0.1 to 0.2 wt. % range when a Field Emission Gun (FEG) system is used. Future directions of X-ray analysis include improvement in X-ray spatial resolution to the I to 2 microns range and MDL as low as 0.01 wt. %. With these improvements the detection of single atoms in the analysis volume will be possible. Other future improvements include the use of clean room techniques for thin specimen preparation, quantification available at the I% accuracy and precision level with light element analysis quantification available at better than the 10% accuracy and precision level, the incorporation of a compact wavelength dispersive spectrometer to improve X-ray spectral resolution, light element analysis and MDL, and instrument improvements including source stability, on-line probe current measurements, stage stability, and computerized stage control. The paper reviews the EELS technique, recognizing that it has been slow to develop and still remains firmly in research laboratories rather than in applications laboratories. Consideration of microanalysis with core-loss edges is given along with a discussion of the limitations such as specimen thickness. Spatial resolution and MDL are considered, recognizing that single atom detection is already possible. Plasmon loss analysis is discussed as well as fine structure analysis. New techniques for energy-loss imaging are also summarized. Future directions in the EELS technique will be the development of new spectrometers and improvements in thin specimen preparation. The microanalysis technique needs to be simplified and software developed so that the EELS technique approaches the relative simplicity of the X-ray technique. Finally, one can expect major improvements in EELS imaging as data storage and processing improvements occur.

Goldstein, J. I.; Williams, D. B.

1992-01-01

169

Win X-ray: a new Monte Carlo program that computes X-ray spectra obtained with a scanning electron microscope.  

PubMed

A new Monte Carlo program, Win X-ray, is presented that predicts X-ray spectra measured with an energy dispersive spectrometer (EDS) attached to a scanning electron microscope (SEM) operating between 10 and 40 keV. All the underlying equations of the Monte Carlo simulation model are included. By simulating X-ray spectra, it is possible to establish the optimum conditions to perform a specific analysis as well as establish detection limits or explore possible peak overlaps. Examples of simulations are also presented to demonstrate the utility of this new program. Although this article concentrates on the simulation of spectra obtained from what are considered conventional thick samples routinely explored by conventional microanalysis techniques, its real power will be in future refinements to address the analysis of sample classifications that include rough surfaces, fine structures, thin films, and inclined surfaces because many of these can be best characterized by Monte Carlo methods. The first step, however, is to develop, refine, and validate a viable Monte Carlo program for simulating spectra from conventional samples. PMID:17481341

Gauvin, Raynald; Lifshin, Eric; Demers, Hendrix; Horny, Paula; Campbell, Helen

2006-02-01

170

Win X-ray: A New Monte Carlo Program that Computes X-ray Spectra Obtained with a Scanning Electron Microscope  

NASA Astrophysics Data System (ADS)

A new Monte Carlo program, Win X-ray, is presented that predicts X-ray spectra measured with an energy dispersive spectrometer (EDS) attached to a scanning electron microscope (SEM) operating between 10 and 40 keV. All the underlying equations of the Monte Carlo simulation model are included. By simulating X-ray spectra, it is possible to establish the optimum conditions to perform a specific analysis as well as establish detection limits or explore possible peak overlaps. Examples of simulations are also presented to demonstrate the utility of this new program. Although this article concentrates on the simulation of spectra obtained from what are considered conventional thick samples routinely explored by conventional microanalysis techniques, its real power will be in future refinements to address the analysis of sample classifications that include rough surfaces, fine structures, thin films, and inclined surfaces because many of these can be best characterized by Monte Carlo methods. The first step, however, is to develop, refine, and validate a viable Monte Carlo program for simulating spectra from conventional samples.

Gauvin, Raynald; Lifshin, Eric; Demers, Hendrix; Horny, Paula; Campbell, Helen

2006-02-01

171

Use of electron cyclotron resonance x-ray source for nondestructive testing application  

SciTech Connect

Electron cyclotron resonance (ECR) technique is being used for generating x rays in the low-energy region (<150 keV). Recently, the source is used for the calibration of thermoluminescent dosimetry (TLD) badges. In order to qualify the ECR x-ray source for imaging application, the source should give uniform flux over the area under study. Lead collimation arrangement is made to get uniform flux. The flux profile is measured using a teletector at different distance from the port and uniform field region of 10x10 cm{sup 2} has been marked at 20 cm from the x-ray exit port. A digital-to-analog converter (DAC) circuit pack is used for examining the source performance. The required dose for nondestructive testing examination has been estimated using a hospital x-ray machine and it is found to be 0.05 mSv. Our source experimental parameters are tuned and the DAC circuit pack was exposed for nearly 7 min to get the required dose value. The ECR x-ray source operating parameters are argon pressure: 10{sup -5} Torr, microwave power: 350 W, and coil current: 0 A. The effective energy of the x-ray spectrum is nearly 40 keV. The x-ray images obtained from ECR x-ray source and hospital medical radiography machine are compared. It is found that the image obtained from ECR x-ray source is suitable for NDT application.

Baskaran, R.; Selvakumaran, T.S. [Radiological Safety Division, Safety Group, Indira Gandhi Center for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India)

2006-03-15

172

Plasma X-ray Spectra Analysis Using Genetic Algorithms Igor E. Golovkin  

E-print Network

Plasma X-ray Spectra Analysis Using Genetic Algorithms Igor E. Golovkin Department of Physics for plasma diagnostics. We use genetic algorithms to automatically analyze experi- mental X-ray line spectra-ray line spectra. 1 INTRODUCTION X-ray spectroscopic analysis is a widely used method for hot dense plasma

Louis, Sushil J.

173

Proposal for a pulse-compression scheme in x-ray free-electron lasers to generate a multiterawatt, attosecond x-ray pulse.  

PubMed

A novel scheme to compress the radiation pulse in x-ray free electron lasers is proposed not only to shorten the pulse length but also to enhance the peak power of the radiation, by inducing a periodic current enhancement with an optical laser and applying a temporal shift between the optical and electron beams. Calculations show that a 10-keV x-ray pulse with a peak power of 5 TW and a pulse length of 50 asec can be generated by applying this scheme to an existing x-ray free electron laser facility. PMID:23473154

Tanaka, Takashi

2013-02-22

174

The soft x-ray instrument for materials studies at the linac coherent light source x-ray free-electron laser  

NASA Astrophysics Data System (ADS)

The soft x-ray materials science instrument is the second operational beamline at the linac coherent light source x-ray free electron laser. The instrument operates with a photon energy range of 480-2000 eV and features a grating monochromator as well as bendable refocusing mirrors. A broad range of experimental stations may be installed to study diverse scientific topics such as: ultrafast chemistry, surface science, highly correlated electron systems, matter under extreme conditions, and laboratory astrophysics. Preliminary commissioning results are presented including the first soft x-ray single-shot energy spectrum from a free electron laser.

Schlotter, W. F.; Turner, J. J.; Rowen, M.; Heimann, P.; Holmes, M.; Krupin, O.; Messerschmidt, M.; Moeller, S.; Krzywinski, J.; Soufli, R.; Fernández-Perea, M.; Kelez, N.; Lee, S.; Coffee, R.; Hays, G.; Beye, M.; Gerken, N.; Sorgenfrei, F.; Hau-Riege, S.; Juha, L.; Chalupsky, J.; Hajkova, V.; Mancuso, A. P.; Singer, A.; Yefanov, O.; Vartanyants, I. A.; Cadenazzi, G.; Abbey, B.; Nugent, K. A.; Sinn, H.; Lüning, J.; Schaffert, S.; Eisebitt, S.; Lee, W.-S.; Scherz, A.; Nilsson, A. R.; Wurth, W.

2012-04-01

175

Advanced water window x-ray microscope design and analysis  

NASA Technical Reports Server (NTRS)

The project was focused on the design and analysis of an advanced water window soft-x-ray microscope. The activities were accomplished by completing three tasks contained in the statement of work of this contract. The new results confirm that in order to achieve resolutions greater than three times the wavelength of the incident radiation, it will be necessary to use aspherical mirror surfaces and to use graded multilayer coatings on the secondary (to accommodate the large variations of the angle of incidence over the secondary when operating the microscope at numerical apertures of 0.35 or greater). The results are included in a manuscript which is enclosed in the Appendix.

Shealy, D. L.; Wang, C.; Jiang, W.; Lin, J.

1992-01-01

176

Intercalation of Trioxatriangulenium Ion in DNA: Binding, Electron Transfer, X-ray Crystallography, and Electronic  

E-print Network

Intercalation of Trioxatriangulenium Ion in DNA: Binding, Electron Transfer, X-ray Crystallography orbital. It binds to duplex DNA by intercalation with a preference for G-C base pairs. Irradiation that affect DNA chemically or structurally is determined by the mode of binding.1,2 Intercalation and groove

Williams, Loren

177

Parametric X-ray radiation from polarized electrons  

NASA Astrophysics Data System (ADS)

Characteristics of parametric X-ray radiation (PXR) from polarized charged fermions based on the quantum theory have been investigated. Spin-dependent part of PXR cross-section on spin of the incident particle has been obtained near the K-edge of crystal target. Estimation of coefficient of PXR process asymmetry was made. The comparison with quantum effects in transition radiation has been carried out.

Potylitsyn, A. P.; Serdyutsky, V. A.; Mazunin, A. V.; Strikhanov, M. N.

2001-01-01

178

Near-monochromatic X-ray beams produced by the free electron laser and Compton backscatter  

Microsoft Academic Search

The intense photon output of a free electron laser may be made to collide with its own high energy electron beam to create nearly monochromatic x-rays using Compton backscatter techniques. These x-rays can be used for imaging and non-imaging diagnostic and therapeutic experiments. The initial configuration of the Vanderbilt Medical Free Electron Laser (Sierra Laser Systems, Sunnyvale, CA) produces intense

FRANK E. CARROLL; JAMES W. WATERS; RON R. PRICE; CHARLES A. BRAU; CARLTON F. ROOS; NORMAN H. TOLK; DAVID R. PICKENS; W. HOYT STEPHENS

1990-01-01

179

Ultrafast electronic dynamics in polyatomic molecules studied using femtosecond vacuum ultraviolet and x-ray pulses  

NASA Astrophysics Data System (ADS)

Time-resolved velocity map photoelectron imaging is performed using sub-20 fs deep ultraviolet and vacuum ultraviolet pulses to study electronic dynamics of isolated polyatomic molecules. The non-adiabatic dynamics of pyrazine, furan and carbon disulfide (CS2) are described as examples. Also described is sub-picosecond time-resolved x-ray direct absorption spectroscopy using a hard x-ray free electron laser (SACLA) and a synchronous near ultraviolet laser to study ultrafast electronic dynamics in solutions.

Suzuki, Toshinori

2014-06-01

180

Hard X-ray photoemission spectroscopy for intrinsic electronic structure of strongly correlated electron systems  

Microsoft Academic Search

In order to clarify the intrinsic bulk electronic structure of strongly-correlated electron systems, we have realized hard X-ray photoemission spectroscopy with high energy-resolution at BL29XUL in SPring-8. The total energy resolution of 75meV was achieved at the excitation energy of 5.95keV. Large probing depth of about 100Å enables us to probe intrinsic bulk electronic structure free from surface condition. The

K. Horiba; M. Taguchi; A. Chainani; Y. Takata; N. Kamakura; S. Shin; M. Yabashi; K. Tamasaku; Y. Nishino; D. Miwa; T. Ishikawa; E. Ikenaga; M. Awaji; A. Takeuchi; K. Kobayashi

2006-01-01

181

Reference-free total reflection X-ray fluorescence analysis of semiconductor surfaces with synchrotron radiation.  

PubMed

Total reflection X-ray fluorescence (TXRF) analysis is a well-established method to monitor lowest level contamination on semiconductor surfaces. Even light elements on a wafer surface can be excited effectively when using high-flux synchrotron radiation in the soft X-ray range. To meet current industrial requirements in nondestructive semiconductor analysis, the Physikalisch-Technische Bundesanstalt (PTB) operates dedicated instrumentation for analyzing light element contamination on wafer pieces as well as on 200- and 300-mm silicon wafer surfaces. This instrumentation is also suited for grazing incidence X-ray fluorescence analysis and conventional energy-dispersive X-ray fluorescence analysis of buried and surface nanolayered structures, respectively. The most prominent features are a high-vacuum load-lock combined with an equipment front end module and a UHV irradiation chamber with an electrostatic chuck mounted on an eight-axis manipulator. Here, the entire surface of a 200- or a 300-mm wafer can be scanned by monochromatized radiation provided by the plane grating monochromator beamline for undulator radiation in the PTB laboratory at the electron storage ring BESSY II. This beamline provides high spectral purity and high photon flux in the range of 0.078-1.86 keV. In addition, absolutely calibrated photodiodes and Si(Li) detectors are used to monitor the exciting radiant power respectively the fluorescence radiation. Furthermore, the footprint of the excitation radiation at the wafer surface is well-known due to beam profile recordings by a CCD during special operation conditions at BESSY II that allow for drastically reduced electron beam currents. Thus, all the requirements of completely reference-free quantitation of TXRF analysis are fulfilled and are to be presented in the present work. The perspectives to arrange for reference-free quantitation using X-ray tube-based, table-top TXRF analysis are also addressed. PMID:17880182

Beckhoff, Burkhard; Fliegauf, Rolf; Kolbe, Michael; Müller, Matthias; Weser, Jan; Ulm, Gerhard

2007-10-15

182

Satellite X ray mappings of sporadic auroral zone electron precipitation events in the local dusk sector  

SciTech Connect

Simultaneous mappings of bremsstrahlung X ray events from the atmosphere resulting from electron precipitation have been performed from a satellite with an array of collimated cadmium telluride spectrometers. The X ray intensities and energy spectra (> or approx. =21 keV) where measured over contiguous view directions. The satellite, P78-1, was launched into a sun-synchronous noon-midnight orbital at approx.600-km altitude on February 24, 1979, and through its spinning motion with a approx.5.5-s period provides continual scans of the X ray sources below. Data are presented from three sporadic events in which the X ray intensities varied strongly with time. Within each of these events, bursts of approx.(30--100) second duration were observed. Some of the bursts were recorded in three or four sensors, thus setting a lower limit to their spatial extent of several hundred kilometers. Other bursts appeared in only one sensor, thereby restricting the area over which they could have been generated. These bursts of X rays emanated primarily from the dusk sector, a local time region where few balloon X ray measurements have been reported. The X ray fluxes were asymmetric about local dusk, the intensities at earlier times being quite low. During one of the X ray bursts in which the precipitation was confined to a relatively small spatial region it is estimated that the total number of electrons (>21 keV) precipitating into the atmosphere was approx.10/sup 23/ per second.

Imhof, W.L.; Kilner, J.R.; Nakano, G.H.; Reagan, J.B.

1980-07-01

183

Development of an x-ray generator using a pyroelectric crystal for x-ray fluorescence analysis on planetary landing missions  

NASA Astrophysics Data System (ADS)

The chemical element abundance on planetary surface is essential for planetary science. We have been developing an active X-ray spectrometer (AXS), which is an in-situ chemical element analyzer based on the X-ray florescence analysis for future planetary landing missions. The AXS consists of an X-ray detector and multiple X-ray sources. Although a pyroelectric X-ray generator is promising for the AXS as an X-ray source, the raise of emission X-ray intensity is necessary for short-time and precise determination of elemental composition. Also, in order to enhance the detection efficiency of light major elements such as Mg, Al, and Si, we have tested the low energy X-ray emission by changing the target material. In this study, the X-ray emission calculation at the target by Monte Carlo simulation and the X-ray emission experiments were carried out. More than 106 cps of the time-averaged X-ray emission rate was achieved in maximum using a LiTaO3 crystal with 4 mm thickness and Cu target with 10 um thickness. The performance of pyroelectric X-ray generator is presented in this paper.

Kusano, Hiroki; Oyama, Yuki; Naito, Masayuki; Nagaoka, Hiroshi; Kuno, Haruyoshi; Shibamura, Eido; Hasebe, Nobuyuki; Amano, Yoshiharu; Kim, Kyeong J.; Matias Lopes, José A.

2014-09-01

184

Inferring the Energy Distribution of Accelerated Electrons in Solar Flares from X-ray Observations  

NASA Technical Reports Server (NTRS)

Knowledge of the energy distribution of electrons accelerated in solar flares is important for constraining possible acceleration mechanisms and for understanding the relationships between flare X-ray sources, radio sources, and particles observed in space. Solar flare hard X-rays are primarily emitted from dense, thick-target regions in the lower atmosphere, but the electrons are understood to be accelerated higher in the corona. Various processes can distort the X-ray spectrum or the energy distribution of electrons before they reach the thick-target region. After briefly reviewing the processes that affect the X-ray spectrum and the electron distribution, I will describe recent results from a study of flare spectra from RHESSI to determine the importance of these processes in inferring the energy distribution of accelerated electrons.

Holman, Gordon D.; Sui, Linhui; Su, Yang

2008-01-01

185

ANALYSIS OF ASTM X-RAY SHRINKAGE RATING FOR STEEL CASTINGS  

E-print Network

1 ANALYSIS OF ASTM X-RAY SHRINKAGE RATING FOR STEEL CASTINGS Kent Carlson1 , Shouzhu Ou1 , Richard, IA ABSTRACT This paper presents the results of two different studies that examined the ASTM x on 128 x-rays that were each given seven ASTM shrinkage x-ray ratings (ratings from five radiographers

Beckermann, Christoph

186

Damage threshold investigation using grazing incidence irradiation by hard x-ray free electron laser  

NASA Astrophysics Data System (ADS)

X-ray free electron lasers (XFELs) with intense and ultra-short pulse X-rays possibly induce damage to optical elements. We investigated the damage thresholds of optical materials by using focusing XFEL beams with sufficient power density for studying ablation phenomena. 1-?m focusing beams with 10 keV photon energy were produced at the XFEL facility SACLA (SPring-8 Angstrom Compact free electron LAser). The focusing beams irradiated samples of rhodium-coated substrate, which is used in X-ray mirror optics, under grazing incident condition.

Koyama, T.; Yumoto, H.; Tono, K.; Sato, T.; Togashi, T.; Inubushi, Y.; Katayama, T.; Kim, J.; Matsuyama, S.; Mimura, H.; Yabashi, M.; Yamauchi, K.; Ohashi, H.

2013-09-01

187

Methods development for diffraction and spectroscopy studies of metalloenzymes at X-ray free-electron lasers.  

PubMed

X-ray free-electron lasers (XFELs) open up new possibilities for X-ray crystallographic and spectroscopic studies of radiation-sensitive biological samples under close to physiological conditions. To facilitate these new X-ray sources, tailored experimental methods and data-processing protocols have to be developed. The highly radiation-sensitive photosystem II (PSII) protein complex is a prime target for XFEL experiments aiming to study the mechanism of light-induced water oxidation taking place at a Mn cluster in this complex. We developed a set of tools for the study of PSII at XFELs, including a new liquid jet based on electrofocusing, an energy dispersive von Hamos X-ray emission spectrometer for the hard X-ray range and a high-throughput soft X-ray spectrometer based on a reflection zone plate. While our immediate focus is on PSII, the methods we describe here are applicable to a wide range of metalloenzymes. These experimental developments were complemented by a new software suite, cctbx.xfel. This software suite allows for near-real-time monitoring of the experimental parameters and detector signals and the detailed analysis of the diffraction and spectroscopy data collected by us at the Linac Coherent Light Source, taking into account the specific characteristics of data measured at an XFEL. PMID:24914169

Kern, Jan; Hattne, Johan; Tran, Rosalie; Alonso-Mori, Roberto; Laksmono, Hartawan; Gul, Sheraz; Sierra, Raymond G; Rehanek, Jens; Erko, Alexei; Mitzner, Rolf; Wernet, Phillip; Bergmann, Uwe; Sauter, Nicholas K; Yachandra, Vittal; Yano, Junko

2014-07-17

188

Femtosecond X-Ray Free Electron Laser Pulse Duration Measurement from Spectral Correlation Function  

SciTech Connect

We present a novel method for measuring the duration of femtosecond x-ray pulses from self-amplified spontaneous emission free electron lasers by performing statistical analysis in the spectral domain. Analytical expressions of the spectral correlation function were derived in the linear regime to extract both the pulse duration and the spectrometer resolution. Numerical simulations confirmed that the method can be also used in the nonlinear regime. The method was demonstrated experimentally at the Linac Coherent Light Source by measuring pulse durations down to 13 fs FWHM.

Lutman, A. A

2012-04-17

189

Femtosecond electron and x-ray generation by laser andplasma-based sources  

SciTech Connect

The generation of ultra-short x-rays by Thomson scattering intense laser pulses from electron beams is discussed, including recent experimental results and methods for enhancing the x-ray flux. A high flux of x-rays in a femtosecond pulse requires the generation of femtosecond electron bunches and a head-on Thomson scattering geometry. The generation of ultrashort electron bunches in a plasma-based accelerator with an injection technique that uses two colliding laser pulses is discussed. Simulations indicate the bunches as short as a few fs can be produced. Conversion of the fs electron pulse to a fs x-ray pulse can be accomplished by Bremsstrahlung or Thomson scattering.

Esarey, E.; Leemans, W.P.

2000-02-01

190

Controlled Betatron X-Ray Radiation from Tunable Optically Injected Electrons  

SciTech Connect

The features of Betatron x-ray emission produced in a laser-plasma accelerator are closely linked to the properties of the relativistic electrons which are at the origin of the radiation. While in interaction regimes explored previously the source was by nature unstable, following the fluctuations of the electron beam, we demonstrate in this Letter the possibility to generate x-ray Betatron radiation with controlled and reproducible features, allowing fine studies of its properties. To do so, Betatron radiation is produced using monoenergetic electrons with tunable energies from a laser-plasma accelerator with colliding pulse injection [J. Faure et al., Nature (London) 444, 737 (2006)]. The presented study provides evidence of the correlations between electrons and x-rays, and the obtained results open significant perspectives toward the production of a stable and controlled femtosecond Betatron x-ray source in the keV range.

Corde, S.; Phuoc, K. Ta; Fitour, R.; Faure, J.; Tafzi, A.; Goddet, J. P.; Malka, V.; Rousse, A. [Laboratoire d'Optique Appliquee, ENSTA ParisTech - CNRS UMR7639 - Ecole Polytechnique, Chemin de la Huniere, 91761 Palaiseau (France)

2011-12-16

191

Impact of ultrafast electronic damage in single-particle x-ray imaging experiments.  

PubMed

In single-particle coherent x-ray diffraction imaging experiments, performed at x-ray free-electron lasers (XFELs), samples are exposed to intense x-ray pulses to obtain single-shot diffraction patterns. The high intensity induces electronic dynamics on the femtosecond time scale in the system, which can reduce the contrast of the obtained diffraction patterns and adds an isotropic background. We quantify the degradation of the diffraction pattern from ultrafast electronic damage by performing simulations on a biological sample exposed to x-ray pulses with different parameters. We find that the contrast is substantially reduced and the background is considerably strong only if almost all electrons are removed from their parent atoms. This happens at fluences of at least one order of magnitude larger than provided at currently available XFEL sources. PMID:23214818

Lorenz, U; Kabachnik, N M; Weckert, E; Vartanyants, I A

2012-11-01

192

Impact of ultrafast electronic damage in single particle x-ray imaging experiments  

E-print Network

In single particle coherent x-ray diffraction imaging experiments, performed at x-ray free-electron lasers (XFELs), samples are exposed to intense x-ray pulses to obtain single-shot diffraction patterns. The high intensity induces electronic dynamics on the femtosecond time scale in the system, which can reduce the contrast of the obtained diffraction patterns and adds an isotropic background. We quantify the degradation of the diffraction pattern from ultrafast electronic damage by performing simulations on a biological sample exposed to x-ray pulses with different parameters. We find that the contrast is substantially reduced and the background is considerably strong only if almost all electrons are removed from their parent atoms. This happens at fluences of at least one order of magnitude larger than provided at currently available XFEL sources.

Lorenz, U; Weckert, E; Vartanyants, I A

2012-01-01

193

Controlled betatron x-ray radiation from tunable optically injected electrons.  

PubMed

The features of Betatron x-ray emission produced in a laser-plasma accelerator are closely linked to the properties of the relativistic electrons which are at the origin of the radiation. While in interaction regimes explored previously the source was by nature unstable, following the fluctuations of the electron beam, we demonstrate in this Letter the possibility to generate x-ray Betatron radiation with controlled and reproducible features, allowing fine studies of its properties. To do so, Betatron radiation is produced using monoenergetic electrons with tunable energies from a laser-plasma accelerator with colliding pulse injection [J. Faure et al., Nature (London) 444, 737 (2006)]. The presented study provides evidence of the correlations between electrons and x-rays, and the obtained results open significant perspectives toward the production of a stable and controlled femtosecond Betatron x-ray source in the keV range. PMID:22243084

Corde, S; Phuoc, K Ta; Fitour, R; Faure, J; Tafzi, A; Goddet, J P; Malka, V; Rousse, A

2011-12-16

194

A simulation of X-ray shielding for a superconducting electron cyclotron resonance ion sourcea)  

NASA Astrophysics Data System (ADS)

It is generally assumed that large amounts of x-rays are emitted from the ion source of an Electron Cyclotron Resonance (ECR) instrument. The total amount of x-rays should be strictly limited to avoid the extra heat load to the cryostat of the superconducting ECR ion source, since they are partly absorbed by the cold mass into the cryostat. A simulation of x-ray shielding was carried out to determine the effective thickness of the x-ray shield needed via the use of Geant4. X-ray spectra of the 10 GHz Nanogan ECR ion source were measured as a function of the thickness variation in the x-ray shield. The experimental results were compared with Geant4 results to verify the effectiveness of the x-ray shield. Based on the validity in the case of the 10 GHz ECR ion source, the x-ray shielding results are presented by assuming the spectral temperature of the 28 GHz ECR ion source.

Park, Jin Yong; Won, Mi-Sook; Lee, Byoung-Seob; Yoon, Jang-Hee; Choi, Seyong; Ok, Jung-Woo; Choi, Jeong-Sik; Kim, Byoung-Chul

2014-02-01

195

Femtosecond Radiation Experiment Detector for X-Ray Free-Electron Laser (XFEL) Coherent X-Ray Imaging  

Microsoft Academic Search

A pixel array detector (PAD) module has been developed at Cornell University for the collection of diffuse diffraction data in anticipation of coherent X-ray imaging experiments that will be conducted at the Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Laboratory. The detector is designed to collect X-rays scattered from monochromatic femtosecond pulses produced by the LCLS X-ray

Hugh T. Philipp; Lucas J. Koerner; Marianne S. Hromalik; Mark W. Tate; Sol M. Gruner

2010-01-01

196

Preliminary X-ray Results From A Multiple Balloon Campaign to Study Relativistic Electron Loss  

NASA Astrophysics Data System (ADS)

The MINIS balloon campaign was successfully conducted in January 2005 to investigate relativistic electron loss mechanisms. Quantifying and understanding losses is an integral part of understanding the variability of relativistic electrons in the radiation belts. Balloon-based experiments directly measure precipitation and thus provide a method for quantifying losses, while the nearly stationary platform allows for the separation of temporal and spatial variations. A new class of precipitation event, characterized by extremely hard spectra, short durations, and complex temporal structure, occurring in the evening to midnight sector, was discovered by the INTERBOA balloon in 1996 and studied further by the MAXIS balloon in 2000. The MINIS campaign provided the first opportunities for multi-point measurements of electron precipitation up to MeV energies, including simultaneous measurements at different longitudes and at near-conjugate locations. Two balloons, each carrying an X-ray spectrometer for measuring the bremsstrahlung produced as electrons precipitate into the atmosphere, were launched from Churchill, Manitoba at 0850 UT on 21 January 2005 and 0140 UT on 25 January 2005. Four balloons, each carrying an X-ray spectrometer, a Z-axis search coil magnetometer, and a 3-axis electric field instrument providing DC electric field and VLF measurements in 3 frequency bands, were launched from the South African Antarctic Station (SANAE IV). The Southern launches took place at 1400 UT on 17 January, 1309 UT on 19 January, 2115 UT on 20 January, and 0950 UT on 24 January 24 2005. In this paper, we present the preliminary results from the MINIS North and South X-ray data. The first and second Southern payloads observed a rarely-seen phenomenon: gamma-ray line emission from nuclear interactions of solar protons in the Earth's atmosphere. When the solar particles abated, there were numerous opportunities for simultaneous observations of MeV precipitation from multiple payloads; we will present the first analysis of these data.

Sample, J. G.; Kokorowski, M.; Millan, R. M.; McCarthy, M.; Holzworth, R. H.; Bering, E. A.; Parks, G. K.; Woodger, L.; Reddell, B. D.; Lay, E.; Pulupa, M.; Bale, S.; O'Brien, T. P.; Blake, J. B.; Lin, R. P.; Moraal, H.; Stoker, P.; Hughes, A. R.; Collier Cameron, A.; Smith, D. M.

2005-05-01

197

Pair production from vacuum at the focus of an X-ray free electron laser  

Microsoft Academic Search

There are definite plans for the construction of X-ray free electron lasers (FEL), both at DESY, where the so-called XFEL is part of the design of the electron–positron linear collider TESLA, as well as at SLAC, where the so-called Linac Coherent Light Source (LCLS) has been proposed. Such an X-ray laser would allow for high-field science applications: one could make

A. Ringwald

2001-01-01

198

ARSA accelerator - small-size source of nanosecond pulses of electron and x-ray radiation  

Microsoft Academic Search

ARSA miniature accelerator is notable for high intensity of radiation and characteristics stability. Near the output window the electron an x ray dose in the air constitutes in a 10 ns pulse 3 x 10⁴ Gy and 3 Gy, respectively. Maximal electron and x-ray quanta energy of 700 keV provides high permeability. Dimensions of the accelerator high-voltage unit are small:

S. L. Elyash; A. I. Alexandrin; E. N. Donskoy

1993-01-01

199

Development of a hard X-ray delay line for X-ray photon correlation spectroscopy and jitter-free pump-probe experiments at X-ray free-electron laser sources  

PubMed Central

A hard X-ray delay line capable of splitting and delaying single X-ray pulses has been developed with the aim of performing X-ray photon correlation spectroscopy (XPCS) and X-ray pump–probe experiments at hard X-ray free-electron laser sources. The performance of the device was tested with 8.39?keV synchrotron radiation. Time delays up to 2.95?ns have been demonstrated. The feasibility of the device for performing XPCS studies was tested by recording static speckle patterns. The achieved speckle contrast of 56% indicates the possibility of performing ultra-fast XPCS studies with the delay line. PMID:21525658

Roseker, Wojciech; Franz, Hermann; Schulte-Schrepping, Horst; Ehnes, Anita; Leupold, Olaf; Zontone, Federico; Lee, Sooheyong; Robert, Aymeric; Grubel, Gerhard

2011-01-01

200

Bayesian Multiscale Analysis of X-Ray Jet Features in High Redshift Quasars  

NASA Astrophysics Data System (ADS)

X-ray emission of powerful quasar jets may be a result of the inverse Compton (IC) process in which the Cosmic Microwave Background (CMB) photons gain energy by interactions with the jet’s relativistic electrons. However, there is no definite evidence that IC/CMB process is responsible for the observed X-ray emission of large scale jets. A step toward understanding the X-ray emission process is to study the Radio and X-ray morphologies of the jet. We implement a sophisticated Bayesian image analysis program, Low-count Image Reconstruction and Analysis (LIRA) (Esch et al. 2004; Conners & van Dyk 2007), to analyze jet features in 11 Chandra images of high redshift quasars (z ~ 2 - 4.8). Out of the 36 regions where knots are visible in the radio jets, nine showed detectable X-ray emission. We measured the ratios of the X-ray and radio luminosities of the detected features and found that they are consistent with the CMB radiation relationship. We derived a range of the bulk lorentz factor (?) for detected jet features under the CMB jet emission model. There is no discernible trend of ? with redshift within the sample. The efficiency of the X-ray emission between the detected jet feature and the corresponding quasar also shows no correlation with redshift. This work is supported in part by the National Science Foundation REU and the Department of Defense ASSURE programs under NSF Grant no.1262851 and by the Smithsonian Institution, and by NASA Contract NAS8-39073 to the Chandra X-ray Center (CXC). This research has made use of data obtained from the Chandra Data Archive and Chandra Source Catalog, and software provided by the CXC in the application packages CIAO, ChIPS, and Sherpa. We thank Teddy Cheung for providing the VLA radio images. Connors, A., & van Dyk, D. A. 2007, Statistical Challenges in Modern Astronomy IV, 371, 101 Esch, D. N., Connors, A., Karovska, M., & van Dyk, D. A. 2004, ApJ, 610, 1213

McKeough, Kathryn; Siemiginowska, A.; Kashyap, V.; Stein, N.

2014-01-01

201

Advances in X-Ray Chemical Analysis, Japan, 45 (2014) ISSN 0911-7806 Analysis of Light Elements with a Portable Electron Probe  

E-print Network

, Analysis of light elements EPMA Si Si X X PPC Si X NiS EDX Al, Ca, Mn, Fe Ni S X , 1. #12;192 45 EPMA Fig.1 Si Si X X Si X X Si X 85 µm PPC ( ) 25 µm Fig.2b EDX Fig.3b Cu X Si #12;194 45 EPMA X Si X NiS SEM Si X Si PPC Si SEM-EDX Ca, Mn, Fe Al Ni S X 1 J. D. Brownridge: Nature, 358, 287 (1992). 2 J. D

Jun, Kawai

202

X ray spectral images of energetic electrons precipitating in the auroral zone  

SciTech Connect

X rays from the Earth's auroral zone are produced by the precipitation of electrons with kilovolt energies. We have used an imaging X ray spectrometer to observe this radiation over a approx.500-km field of view divided into 16 pixels. The observations were made by an experiment on the S81-1 satellite (SEEP: Stimulated Emission of Energetic Particles) during June 1982. Using high spectral resolution 4- to 40-keV X ray data, we have calculated the flux and spectral slope of the precipitating electrons. We have conducted, for the first time, a systematic survey of the characteristics of electrons spectra in a large number of individual X ray features. Most of the precipitation is confined to well-defined locations, arcs or isolated patches, separated by regions where no X ray flux was detected. Narrow features are typical for energetic electrons above 5 keV, in contrast to lower-energy electrons, which may produce relatively diffuse optical images. These X ray images have produced two-dimensional maps of precipitation which show no trends of spectral hardness with position, while on the same spatial scales there are order of magnitude changes in the flux of precipitating electrons. copyright American Geophysical Union 1988

Datlowe, D.W.; Imhof, W.L.; Voss, H.D.

1988-08-01

203

Defect analysis in crystals using X-ray topography  

Microsoft Academic Search

A brief review of X-ray topography—a nondestructive method for direct observation and characterization of defects in single crystals—is presented here. The origin and development of this characterization method and the different techniques derived from it are described. Emphasis is placed on synchrotron X-ray topography and its application in studying various crystal imperfec- tions. Mechanisms of contrast formation on X-ray topographs

Balaji Raghothamachar; Govindhan Dhanaraj; Jie Bai; Michael Dudley

2006-01-01

204

X-ray free-electron lasers--present and future capabilities [Invited  

SciTech Connect

The Linac Coherent Light Source is now in operation as an X-ray free-electron laser (FEL) user facility. It produces coherent pulses of 550-10,000 eV X-rays of duration adjustable from <10 fs to 500 fs. Typical peak power is in excess of 20 GW. The facility will soon be joined by several X-ray FELs under construction around the world. This article will provide an abridged history of free-electron lasers, a description of some basic physics regarding free-electron laser light amplification, and an overview of the rapidly growing list of examples in which lasers will be used in the control and operation of X-ray FELs.

Galayda, John N.; Arthur, John; Ratner, Daniel F.; White, William E. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States)

2010-11-15

205

X-ray Free-Electron Lasers - Present and Future Capabilities [Invited  

SciTech Connect

The Linac Coherent Light Source is now in operation as an X-ray free-electron laser (FEL) user facility. It produces coherent pulses of 550-10,000 eV X-rays of duration adjustable from <10 fsto500 fs. Typical peak power is in excess of 20 GW. The facility will soon be joined by several X-ray FELs under construction around the world. This article will provide an abridged history of free-electron lasers, a description of some basic physics regarding free-electron laser light amplification, and an overview of the rapidly growing list of examples in which lasers will be used in the control and operation of X-ray FELs.

Galayda, John; Ratner, John Arthur:a Daniel F.; White, William E.; /SLAC

2011-11-16

206

Observation of pulsed x-ray trains produced by laser-electron Compton scatterings  

SciTech Connect

X-ray generation based on laser-electron Compton scattering is one attractive method to achieve a compact laboratory-sized high-brightness x-ray source. We have designed, built, and tested such a source; it combines a 50 MeV multibunch electron linac with a mode-locked 1064 nm laser stored and amplified in a Fabry-Perot optical cavity. We directly observed trains of pulsed x rays using a microchannel plate detector; the resultant yield was found to be 1.2x10{sup 5} Hz in good agreement with prediction. We believe that the result has demonstrated good feasibility of linac-based compact x-ray sources via laser-electron Compton scatterings.

Sakaue, Kazuyuki; Washio, Masakazu [Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Araki, Sakae; Fukuda, Masafumi; Higashi, Yasuo; Honda, Yosuke; Omori, Tsunehiko; Taniguchi, Takashi; Terunuma, Nobuhiro; Urakawa, Junji [KEK (High Energy Accelerator Research Organization), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Sasao, Noboru [Department of Physics, Kyoto University, Sakyo, Kyoto 606-8502 (Japan)

2009-12-15

207

Analysis of tungsten carbides by X-ray fluorescence spectrometry.  

PubMed

Five sample presentation techniques were examined for the X-ray fluorescence spectrometric analysis of tungsten carbide alloys in powder and cemented forms. Powder samples may be oxidized by air at 600 degrees before fusion (I), or preferably by lithium nitrate during fusion (II); the fusion is effected with lithium-lanthanum tetraborate followed by briquetting with graphite. Powder samples may also be blended with wax and briquetted (III). Cemented carbides are surface-prepared with silicon carbide before analysis (V). Briquettes prepared by blending carbide powder, lithium-lanthanum tetraborate and graphite (IV), give poor reproducibility, however, owing to micro-absorption effects the technique is not recommended. The determination of eight common elements in tungsten carbide is discussed and the relative standard deviations are 0.002-0.004 for major and 0.008-0.01 for minor elements. PMID:18961988

Kinson, K; Knott, A C; Belcher, C B

208

Use of backscattered electron imaging, X-ray microanalysis and X-ray microscopy in demonstrating physiological cell death  

SciTech Connect

The cytochemical localization of enzymatic activity by means of backscattered electron imaging (BEI) is reviewed and the application of BEI to changes in acid phosphatase and ATPase distribution during physiological (programmed) cell death in Heliothis midgut is explored. Programmed cell death entails the release of nascent free acid phosphatase as extracisternal hydrolase. This shift can readily be detected by means of the atomic number contrast imparted by BEI of the lead phosphatase reaction product, thus enabling the distribution of dying cells to be mapped. BEI is particularly useful in this context as it allows the examination of bulk specimens at low magnification. Death of cells is also accompanied by a collapse in ATPase activity which shows up as cytochemically negative areas in the X-ray microscope and by means of BEI. Acid phosphatase in normal cells is localized in the apical microvilli and lysosomes. Senescent or dying cells, however, clearly show a basally situated free hydrolase which migrates throughout the cell. Parallel TEM results confirm that this enzyme is ribosomal and extracisternal rather than lysosomal in origin. ATPase activity is largely limited to the apical microvilli, although there is some activity associated with the basal plasma membranes. The apical ATPase, however is partially resistant to ouabain. Young and mature cells are positive although in the latter case some microvilli may be lost as the cells acquire a negative cap or dome. Inhibition by bromotetramizole indicates that apical activity is not to any significant extent contributed to by alkaline phosphatase. Degenerate or dead cells are negative and can be seen as a mozaic of black patches among normal cells when imaged by means of BEI or X-ray microscopy.

Bowen, I.D.; Worrill, N.A.; Winters, C.A.; Mullarkey, K.

1988-09-01

209

Two-colour hard X-ray free-electron laser with wide tunability  

NASA Astrophysics Data System (ADS)

Ultrabrilliant, femtosecond X-ray pulses from X-ray free-electron lasers (XFELs) have promoted the investigation of exotic interactions between intense X-rays and matters, and the observation of minute targets with high spatio-temporal resolution. Although a single X-ray beam has been utilized for these experiments, the use of multiple beams with flexible and optimum beam parameters should drastically enhance the capability and potentiality of XFELs. Here we show a new light source of a two-colour double-pulse (TCDP) XFEL in hard X-rays using variable-gap undulators, which realizes a large and flexible wavelength separation of more than 30% with an ultraprecisely controlled time interval in the attosecond regime. Together with sub-10-fs pulse duration and multi-gigawatt peak powers, the TCDP scheme enables us to elucidate X-ray-induced ultrafast transitions of electronic states and structures, which will significantly contribute to the advancement of ultrafast chemistry, plasma and astronomical physics, and quantum X-ray optics.

Hara, Toru; Inubushi, Yuichi; Katayama, Tetsuo; Sato, Takahiro; Tanaka, Hitoshi; Tanaka, Takashi; Togashi, Tadashi; Togawa, Kazuaki; Tono, Kensuke; Yabashi, Makina; Ishikawa, Tetsuya

2013-12-01

210

Hard X-ray Spectra and Positions of Solar Flares observed by RHESSI: photospheric albedo, directivity and electron spectra  

E-print Network

We investigate the signature of the photospheric albedo contribution in solar flare hard X-ray spectra, the effect of low energy cutoffs in electron spectra, and the directivity of hard X-ray emission. Using Ramaty High Energy Solar Spectroscopic Imager (RHESSI) flare data we perform a statistical analysis of spatially integrated spectra and positions of solar flares. We demonstrate clear centre-to-limb variation of photon spectral indices in the 15-20 keV energy range and a weaker dependency in the 20-50 keV range which is consistent with photospheric albedo as the cause. The results also suggest that low-energy cutoffs sometimes inferred in mean electron spectra are an artefact of albedo. We also derive the anisotropy (ratio of downward/observer directed photons) of hard X-ray emission in the 15-20 keV range for various heliocentric angles.

J. Kasparova; E. P. Kontar; J. C. Brown

2007-01-30

211

Ultrashort x-ray pulse generation by electron beam slicing in storage rings  

NASA Astrophysics Data System (ADS)

We propose a new method to generate ultrashort x-ray pulses using focused short low energy (˜20 MeV) electron bunches to create short slices of electrons from the circulating electron bunches in a synchrotron radiation storage ring. When a low energy electron bunch crosses from the top of a high energy storage ring electron bunch, its Coulomb force will kick a short slice from the core of the storage ring electron bunch. The separated slices, when passing through an undulator, will radiate ultrashort x-ray pulses at about 160 fs. We discuss the advantages, challenges, and provide data which confirm the feasibility of this new method.

He, A.; Willeke, F.; Yu, L. H.

2014-04-01

212

Detection of soft X-rays with NEA III-V photocathodes. [Negative Electron Affinity X-ray detector for astronomy  

NASA Technical Reports Server (NTRS)

A description is presented of the results of tests on an X-ray photomultiplier containing a negative electron affinity (NEA) photocathode. This device makes it possible to investigate the response of the NEA photocathode to X-rays of various energies. The obtained data provide a basis for the determination of the photoelectron yield and energy resolution of the considered photocathode as a function of energy in the range from 0.8 to 3 keV. The investigation demonstrates the feasibility of using an NEA III-V photocathode for the detection of soft X-rays.

Bardas, D.; Kellogg, E.; Murray, S.; Enck, R., Jr.

1978-01-01

213

A Sealed, UHV Compatible, Soft X-ray Detector Utilizing Gas Electron Multipliers  

SciTech Connect

An advanced soft X-ray detector has been designed and fabricated for use in synchrotron experiments that utilize X-ray absorption spectroscopy in the study a wide range of materials properties. Fluorescence X-rays, in particular C{sub K} at 277eV, are converted in a low pressure gas medium, and charge multiplication occurs in two gas electron multipliers, fabricated in-house from glass reinforced laminate, to enable single photon counting. The detector satisfies a number of demanding characteristics often required in synchrotron environments, such as UHV compatibility compactness, long-term stability, and energy resolving capability.

Schaknowski, N.A.; Smith, G.

2009-10-25

214

X-Ray Diffraction Analysis of NLO Crystals: Traditional Applications and More New Opportunities  

NASA Technical Reports Server (NTRS)

Single crystal X-ray diffraction analysis is one of the more important methods for the molecular and crystal structure determination of matter and therefore it has a great importance in material science including design and engineering of different compounds with non-linear optical (NLO) properties. It was shown in our previous publications that this method provides unique information about molecular structure of NLO compounds, their crystal symmetry and crystal packing arrays, molecular conformation and geometries and many other structural and electronic characteristics that are important for understanding the nature of NLO properties of solids. A very new application of the X-ray diffraction method is related to analysis of the electron density distribution p(r) in crystals and some of its characteristics (atomic and group charges, dipole and higher multipole moments, etc.), that may be obtained directly form the diffraction measurements. In the present work, we will discuss our preliminary low temperature high-resolution X-ray data for the m-nitroaniline (mNA) single crystal (VI). This is one of the "classical" organic NLO materials and electron density distribution analysis in this simple compound has a great scientific interest.

Antipin, Mikhail Yu.; Clark, Ronald D.; Nesterov, Vladimir N.

1998-01-01

215

Multichord time-resolved electron temperature measurements by the x-ray absorber-foil method on TFTR  

SciTech Connect

Absorber foils have been installed in the TFTR X-Ray Imaging System to permit measurement of the electron temperature along 10 to 30 chords spaced at 5-12.5 cm with a time resolution of less than 100 ..mu..s. The technique uses the ratio of x-ray fluxes transmitted through two different foils. The ratio depends mainly on electron temperature. Simulations show that strong impurity line radiation can distort this ratio. To correct for these effects, special beryllium-scandium filters are employed to select the line-free region between 2 and 4.5 keV. Other filter pairs allow corrections for Fe L and Ni L line radiation as well as Ti K and Ni K emission. Good accuracy is also obtained with simple beryllium filters, provided that impurity corrections are incorporated in the analysis, taking line intensities from the x-ray pulse-height analysis diagnostic. A description of modeling calculations and a comparison of temperature values from this diagnostic with data from the x-ray pulse height analysis, the electron cyclotron emission, and the Thomson scattering diagnostics are presented. Several applications of the absorber foil electron temperature diagnostic on TFTR are discussed.

Kiraly, J.; Bitter, M.; Efthimion, P.; von Goeler, S.; Grek, B.; Hill, K.W.; Johnson, D.; McGuire, K.; Sauthoff, N.; Sesnic, S.

1985-09-01

216

Phase recovery and lensless imaging by iterative methods in optical, X-ray and electron diffraction.  

PubMed

Thomas Young's quantitative analysis of interference effects provided the confidence needed to revive the wave theory of light, and firmly established the concept of phase in optics. Phase plays a similarly fundamental role in matter-wave interferometry, for which the field-emission electron microscope provides ideal instrumentation. The wave-particle duality is vividly demonstrated by experimental 'Young's fringes' using coherent electron beams under conditions in which the flight time is less than the time between particle emission. A brief historical review is given of electron interferometry and holography, including the Aharonov-Bohm effect and the electron Sagnac interferometer. The simultaneous development of phase-contrast imaging at subnanometre spatial resolution has greatly deepened our understanding of atomic processes in biology, materials science and condensed-matter physics, while electron holography has become a routine tool for the mapping of electrostatic and magnetic fields in materials on a nanometre scale. The encoding of phase information in scattered farfield intensities is discussed, and non-interferometric, non-crystallographic methods for phase retrieval are reviewed in relationship to electron holography. Examples of phase measurement and diffraction-limited imaging using the hybrid input-output iterative algorithm are given, including simulations for soft X-ray imaging, and new experimental results for coherent electron and visible-light scattering. Image reconstruction is demonstrated from experimental electron and visible-light Fraunhofer diffraction patterns. The prospects this provides for lensless imaging using particles for which no lenses exist (such as neutrons, condensates, coherent atom beams and X-rays) are discussed. These new interactions can be expected to provide new information, perhaps, for example, in biology, with the advantage of less damage to samples. PMID:12804284

Spence, J C H; Weierstall, U; Howells, M

2002-05-15

217

Electron-beam and x-ray lithographic characteristics of the optical resist ARCH  

Microsoft Academic Search

The multi-component, positive acting, chemically amplified deep-UV ((lambda) equals 248 nm) resist ARCH, has been evaluated for use in proximity x-ray and electron-beam lithography. Characterization of the x-ray lithographic response of ARCH resist using a pulsed laser point source ((lambda) equals 1.4 nm) proximity print stepper resulted in a process producing sub-0.20 micrometers features at a dose of 22 mJ\\/cm2.

Anthony E. Novembre; Regine G. Tarascon; Omkaram Nalamasu; Linus A. Fetter; Kevin J. Bolan; Chester S. Knurek; Norbert Muenzel; Heinz E. Holzwarth

1995-01-01

218

Ultra fast electron beam X-ray computed tomography for two-phase flow measurement  

Microsoft Academic Search

Electron beam X-ray CT is a new technique for a fast measurement of multiphase flows with frame rates of 1000 images per second and more. It gives, in principle, quantitatively accurate images of the flow at high spatial resolution and it is non-intrusive since moderately radiation absorbing vessel walls can be penetrated by X-rays. However, on the road to a

F. Fischer; U. Hampel

2010-01-01

219

Femtosecond diffractive imaging with a soft-X-ray free-electron laser  

Microsoft Academic Search

Theory predicts that, with an ultrashort and extremely bright coherent X-ray pulse, a single diffraction pattern may be recorded from a large macromolecule, a virus or a cell before the sample explodes and turns into a plasma. Here we report the first experimental demonstration of this principle using the FLASH soft-X-ray free-electron laser. An intense 25fs, 4×1013Wcm-2 pulse, containing 1012

Henry N. Chapman; Anton Barty; Michael J. Bogan; Sébastien Boutet; Matthias Frank; Stefan P. Hau-Riege; Stefano Marchesini; Bruce W. Woods; Sasa Bajt; W. Henry Benner; Richard A. London; Elke Plönjes; Marion Kuhlmann; Rolf Treusch; Stefan Düsterer; Thomas Tschentscher; Jochen R. Schneider; Eberhard Spiller; Thomas Möller; Christoph Bostedt; Matthias Hoener; David A. Shapiro; Keith O. Hodgson; David van der Spoel; Florian Burmeister; Magnus Bergh; Carl Caleman; Gösta Huldt; M. Marvin Seibert; Filipe R. N. C. Maia; Richard W. Lee; Abraham Szöke; Nicusor Timneanu; Janos Hajdu

2006-01-01

220

XPCS at the European X-ray free electron laser facility  

Microsoft Academic Search

The European X-ray free electron laser source (XFEL) will provide highly brilliant (B>1033ph\\/s\\/mm2\\/mrad2\\/0.1% bw) and coherent X-ray beams. The pulse structure and the unprecedented brightness will allow one for the first time to study fast dynamics in the time domain, thus giving direct access to the dynamic response function S(Q,t), instead of S(Q,?), which is of central importance for a

G. Grübel; G. B. Stephenson; C. Gutt; H. Sinn; Th. Tschentscher; Hasylab

2007-01-01

221

Femtosecond Diffractive Imaging with a Soft-X-Ray Free-Electron Laser  

Microsoft Academic Search

Theory predicts that with an ultrashort and extremely bright coherent X-ray pulse, a single diffraction pattern may be recorded from a large macromolecule, a virus, or a cell before the sample explodes and turns into a plasma. Here we report the first experimental demonstration of this principle using the FLASH soft X-ray free-electron laser. An intense 25 fs, 4 x

Bogan; Michael James

2010-01-01

222

Accurate macromolecular structures using minimal measurements from X-ray free-electron lasers.  

PubMed

X-ray free-electron laser (XFEL) sources enable the use of crystallography to solve three-dimensional macromolecular structures under native conditions and without radiation damage. Results to date, however, have been limited by the challenge of deriving accurate Bragg intensities from a heterogeneous population of microcrystals, while at the same time modeling the X-ray spectrum and detector geometry. Here we present a computational approach designed to extract meaningful high-resolution signals from fewer diffraction measurements. PMID:24633409

Hattne, Johan; Echols, Nathaniel; Tran, Rosalie; Kern, Jan; Gildea, Richard J; Brewster, Aaron S; Alonso-Mori, Roberto; Glöckner, Carina; Hellmich, Julia; Laksmono, Hartawan; Sierra, Raymond G; Lassalle-Kaiser, Benedikt; Lampe, Alyssa; Han, Guangye; Gul, Sheraz; DiFiore, Dörte; Milathianaki, Despina; Fry, Alan R; Miahnahri, Alan; White, William E; Schafer, Donald W; Seibert, M Marvin; Koglin, Jason E; Sokaras, Dimosthenis; Weng, Tsu-Chien; Sellberg, Jonas; Latimer, Matthew J; Glatzel, Pieter; Zwart, Petrus H; Grosse-Kunstleve, Ralf W; Bogan, Michael J; Messerschmidt, Marc; Williams, Garth J; Boutet, Sébastien; Messinger, Johannes; Zouni, Athina; Yano, Junko; Bergmann, Uwe; Yachandra, Vittal K; Adams, Paul D; Sauter, Nicholas K

2014-05-01

223

Use of electron cyclotron resonance x-ray source for nondestructive testing application  

Microsoft Academic Search

Electron cyclotron resonance (ECR) technique is being used for generating x rays in the low-energy region (<150 keV). Recently, the source is used for the calibration of thermoluminescent dosimetry (TLD) badges. In order to qualify the ECR x-ray source for imaging application, the source should give uniform flux over the area under study. Lead collimation arrangement is made to get

R. Baskaran; T. S. Selvakumaran

2006-01-01

224

X-ray measurements of lattice parameter changes in electron irradiated silicon  

Microsoft Academic Search

In this work a double-source, double-crystal x-ray spectrometer and a double-crystal x-ray topograph were constructed and refined. The spectrometer can compare the lattice parameters of two highly perfect silicon crystals to an accuracy of 2 parts per billion. Silicon samples doped with various concentrations of boron or arsenic were irradiated with 1-MeV electrons. It was found that the lattice parameters

Stuckey Kauffman

1984-01-01

225

Bremsstrahlung X ray images of isolated electron patches at high latitudes  

Microsoft Academic Search

Small isolated patches of energetic electron precipitation have been observed at high latitudes with a bremsstrahlung X-ray imager in the Stimulated Emission of Energetic Particles (SEEP) payload on the polar-orbiting S81-1 satellite. Twenty-nine patches of X-rays with typical widths of about 200 km were observed in June 1982 at invariant latitudes between 65 and 83 deg, with a median latitude

W. L. Imhof; H. D. Voss; D. W. Datlowe; J. Mobilia

1985-01-01

226

Bremsstrahlung x ray images of isolated electron patches at high latitudes  

Microsoft Academic Search

Small isolated patches of energetic electron precipitation have been observed at high latitudes with a bremsstrahlung X ray imager in the Stimulated Emission of Energetic Particles (SEEP) payload on the polar-orbiting S81-1 satellite. Twenty-nine patches of X rays (>4 keV) with typical widths of approx.200 km were observed in June 1982 at invariant latitudes between 65° and 83° with a

W. L. Imhof; H. D. Voss; D. W. Datlowe; J. Mobilia

1985-01-01

227

Synchrotron Self-Compton Analysis of TeV X-ray Selected BL Lacertae Objects  

E-print Network

We introduce a methodology for analysis of multiwavelength data from X-ray selected BL Lac (XBL) objects detected in the TeV regime. By assuming that the radio--through--X-ray flux from XBLs is nonthermal synchrotron radiation emitted by isotropically-distributed electrons in the randomly oriented magnetic field of a relativistic blazar jet, we obtain the electron spectrum. This spectrum is then used to deduce the synchrotron self-Compton (SSC) spectrum as a function of the Doppler factor, magnetic field, and variability timescale. The variability timescale is used to infer the comoving blob radius from light travel-time arguments, leaving only two parameters. With this approach, we accurately simulate the synchrotron and SSC spectrum of flaring XBLs in the Thomson through Klein-Nishina regimes. Photoabsorption by interactions with internal jet radiation and the intergalactic background light (IBL) is included. Doppler factors, magnetic fields, and absolute jet powers are obtained by fitting the {\\em HESS} an...

Finke, Justin; Boettcher, Markus

2008-01-01

228

In Situ Mineralogical Analysis of Planetary Materials Using X-Ray Diffraction and X-Ray Fluorescence  

NASA Technical Reports Server (NTRS)

Remote observations of Mars have led scientists to believe that its early climate was similar to that of the early Earth, having had abundant liquid water and a dense atmosphere. One of the most fascinating questions of recent times is whether simple bacterial life developed on Mars (as it did on the Earth) during this early element period. Analyses of SNC meteorites have broadened considerably our knowledge of the chemistry of certain types of Martian rocks, underscoring the tantalizing possibility of early hydrothermal systems and even of ancient bacterial life. Detailed analyses of SNC meteorites in Terrestrial laboratories utilize the most sophisticated organic, isotopic and microscopic techniques in existence. Indeed; it is unlikely that the key biogenic indicators used in McKay et al (ibid) could be identified by a remote instrument on the surface of Mars. As a result, it is probable that any robotic search for evidence of an ancient Martian biosphere will have as its focus the identification of key minerals in likely host rocks rather than the direct detection of organic or isotopic biomarkers. Even on a sample return mission, mineralogical screening will be utilized to choose the most likely candidate rocks. X-ray diffraction (XRD) is the only technique that can provide a direct determination of the crystal structures of the phases present within a sample. When many different crystalline phases are present, quantitative analysis is better constrained if used in conjunction with a determination of elemental composition, obtainable by X-ray fluorescence (XRF) using the same X-ray source as for XRD. For planetary surface analysis, a remote instrument combining XRD and XRF could be used for mineralogical characterization of both soils and rocks. We are designing a remote XRD/XRF instrument with this objective in mind. The instrument concept pays specific attention to constraints in sample preparation, weight, volume, power, etc. Based on the geometry of a pinhole camera (transmission geometry, flat two-dimensional detector perpendicular to the direct beam), the instrument (which we call CHEMIN, for Chemistry and Mineralogy) uses an X-ray sensitive CCD detector which will allow concurrent positional and energy-dispersive analysis of collected photons. Thus XRF (energy) and XRD (geometry) analysis of transmitted X-rays will be performed at the same time. Tests performed with single minerals and simple mixtures give promising results. Refinements of the prototype promise interpretable results on complex samples.

Sarrazin, P.; Blake, D.; Vaniman, D.; Chang, Sherwood (Technical Monitor)

1996-01-01

229

Coherence-based transverse measurement of synchrotron x-ray radiation from relativistic laser-plasma interaction and of laser-accelerated electrons  

Microsoft Academic Search

Fresnel diffraction of x-ray beam from laser-plasma interaction shows incoherent-source diameter¿8 ¿m. Analysis shows this corresponds to accelerated electron profile in plasma agreeing with simulation.

Rahul C. Shah; F. Albert; K. Ta Phuoc; F. Burgy; J.-P. Rousseau; O. Shevchenko; D. Boschetto; A. Rousse; Alexander Pukhov; Sergei Kiselev

2007-01-01

230

Electronic structure of hemin in solution studied by resonant X-ray emission spectroscopy and electronic structure calculations.  

PubMed

Resonant inelastic X-ray scattering spectra at the iron L-edge from hemin in dimethyl sulfoxide liquid solution are reported. Our experiments, which are interpreted with the help of electronic structure calculations, support earlier assignments of hemin-solvent interactions, including the iron spin state and the role of the chloride ligand obtained from a total fluorescence yield study. The analysis of the explicit radiative relaxation channels of 2p core-level excited iron, explored in the present work, allows for a rather quantitative assignment of the orbitals involved in the excitation-deexcitation process of the core-excited hemin in solution. We specifically distinguish between contributions of partially and fully occupied valence orbitals to the broad X-ray emission band. In addition, our calculations reveal a detailed picture of the character of these orbitals. PMID:25068599

Atak, Kaan; Golnak, Ronny; Xiao, Jie; Suljoti, Edlira; Pflüger, Mika; Brandenburg, Tim; Winter, Bernd; Aziz, Emad F

2014-08-21

231

Soft X Ray Telescope (SXT) focus error analysis  

NASA Technical Reports Server (NTRS)

The analysis performed on the soft x-ray telescope (SXT) to determine the correct thickness of the spacer to position the CCD camera at the best focus of the telescope and to determine the maximum uncertainty in this focus position due to a number of metrology and experimental errors, and thermal, and humidity effects is presented. This type of analysis has been performed by the SXT prime contractor, Lockheed Palo Alto Research Lab (LPARL). The SXT project office at MSFC formed an independent team of experts to review the LPARL work, and verify the analysis performed by them. Based on the recommendation of this team, the project office will make a decision if an end to end focus test is required for the SXT prior to launch. The metrology and experimental data, and the spreadsheets provided by LPARL are used at the basis of the analysis presented. The data entries in these spreadsheets have been verified as far as feasible, and the format of the spreadsheets has been improved to make these easier to understand. The results obtained from this analysis are very close to the results obtained by LPARL. However, due to the lack of organized documentation the analysis uncovered a few areas of possibly erroneous metrology data, which may affect the results obtained by this analytical approach.

Ahmad, Anees

1991-01-01

232

Advances in X-Ray Chemical Analysis, Japan, 41 (2010) ISSN 0911-7806 Applying Pyroelectric Crystal to Small High Energy X-Ray Source  

E-print Network

Advances in X-Ray Chemical Analysis, Japan, 41 (2010) ISSN 0911-7806 © X Applying Pyroelectric Crystal to Small High Energy X-Ray Source Eisuke HIRO, Takashi YAMAMOTO and Jun KAWAI #12;#12;41 195 X Adv. X-Ray. Chem. Anal., Japan 41, pp.195-200 (2010) 606-8501 1-1 770-8502 X Applying Pyroelectric

Jun, Kawai

233

Calculating the X-Ray Fluorescence from the Planet Mercury Due to High-Energy Electrons  

NASA Technical Reports Server (NTRS)

The least-studied terrestrial planet is Mercury due to its proximity to the Sun, which makes telescopic observations and spacecraft encounters difficult. Our lack of knowledge about Mercury should change in the near future due to the recent launching of MESSENGER, a Mercury orbiter. Another mission (BepiColombo) is currently being planned. The x-ray spectrometer on MESSENGER (and planned for BepiColombo) can characterize the elemental composition of a planetary surface by measuring emitted fluorescent x-rays. If electrons are ejected from an atom s inner shell by interaction with energetic particles such as photons, electrons, or ions, electrons from an outer shell can transfer to the inner shell. Characteristic x-rays are then emitted with energies that are the difference between the binding energy of the ion in its excited state and that of the ion in its ground state. Because each element has a unique set of energy levels, each element emits x-rays at a unique set of energies. Electrons and ions usually do not have the needed flux at high energies to cause significant x-ray fluorescence on most planetary bodies. This is not the case for Mercury where high-energy particles were detected during the Mariner 10 flybys. Mercury has an intrinsic magnetic field that deflects the solar wind, resulting in a bow shock in the solar wind and a magnetospheric cavity. Electrons and ions accelerated in the magnetosphere tend to follow its magnetic field lines and can impact the surface on Mercury s dark side Modeling has been done to determine if x-ray fluorescence resulting from the impact of high-energy electrons accelerated in Mercury's magnetosphere can be detected by MESSENGER. Our goal is to understand how much bulk chemical information can be obtained from x-ray fluorescence measurements on the dark side of Mercury.

Burbine, T. H.; Trombka, J. I.; Bergstrom, P. M., Jr.; Christon, S. P.

2005-01-01

234

Prevailing Features of X-Ray-Induced Molecular Electron Spectra Revealed with Fullerenes  

NASA Astrophysics Data System (ADS)

X-ray photoabsorption from intense short pulses by a molecule triggers complicated electron and subsequently ion dynamics, leading to photoelectron spectra, which are difficult to interpret. Illuminating fullerenes offers a way to separate out the electron dynamics since the cage structure confines spatially the origin of photo- and Auger electrons. Together with the sequential nature of the photoprocesses at intensities available at x-ray free-electron lasers, this allows for a remarkably detailed interpretation of the photoelectron spectra, as we will demonstrate. The general features derived can serve as a paradigm for less well-defined situations in other large molecules or clusters.

Camacho Garibay, Abraham; Saalmann, Ulf; Rost, Jan M.

2014-08-01

235

Prevailing features of x-ray-induced molecular electron spectra revealed with fullerenes.  

PubMed

X-ray photoabsorption from intense short pulses by a molecule triggers complicated electron and subsequently ion dynamics, leading to photoelectron spectra, which are difficult to interpret. Illuminating fullerenes offers a way to separate out the electron dynamics since the cage structure confines spatially the origin of photo- and Auger electrons. Together with the sequential nature of the photoprocesses at intensities available at x-ray free-electron lasers, this allows for a remarkably detailed interpretation of the photoelectron spectra, as we will demonstrate. The general features derived can serve as a paradigm for less well-defined situations in other large molecules or clusters. PMID:25192093

Camacho Garibay, Abraham; Saalmann, Ulf; Rost, Jan M

2014-08-22

236

Soft X-ray ARPES and Fermiology of strongly correlated electron systems and PES by hard X-ray and extremely low energy photons  

Microsoft Academic Search

Bulk sensitivity is inevitable for photoelectron spectroscopy (PES) when one studies bulk electronic structures of strongly correlated electron systems, which are often much different from surface electronic structures. Combination of soft and hard X-ray PES (SXPES and HAXPES) is a promising approach for this purpose by quantitatively evaluating the contribution of the surface in the observed angle integrated PES spectra.

Shigemasa Suga; Akira Sekiyama

2010-01-01

237

Laboratory-size three-dimensional x-ray microscope with Wolter type I mirror optics and an electron-impact water window x-ray source.  

PubMed

We constructed a laboratory-size three-dimensional water window x-ray microscope that combines wide-field transmission x-ray microscopy with tomographic reconstruction techniques, and observed bio-medical samples to evaluate its applicability to life science research fields. It consists of a condenser and an objective grazing incidence Wolter type I mirror, an electron-impact type oxygen K? x-ray source, and a back-illuminated CCD for x-ray imaging. A spatial resolution limit of around 1.0 line pairs per micrometer was obtained for two-dimensional transmission images, and 1-?m scale three-dimensional fine structures were resolved. PMID:25273730

Ohsuka, Shinji; Ohba, Akira; Onoda, Shinobu; Nakamoto, Katsuhiro; Nakano, Tomoyasu; Miyoshi, Motosuke; Soda, Keita; Hamakubo, Takao

2014-09-01

238

Investigation of the electronic structure of diphenylsilane using the density functional theory method and X-ray emission spectroscopy  

NASA Astrophysics Data System (ADS)

The electronic structure of diphenylsilane Ph2SiH2 has been investigated using X-ray emission spectroscopy and quantum-chemical calculations in the approximation of the density functional theory. The SiK_{? _1 } X-ray emission spectrum of Ph2SiH2 has been constructed using the results of theoretical calculations. The energy structure and shape of this spectrum are in good agreement with the experiment. A comparative analysis of the results of calculations and the fine structure of the experimental SiK_{? _1 } X-ray emission spectrum of diphenylsilane has made it possible to describe in detail the specific features of the chemical interaction in this compound. The quantitative characteristics of the hybridization of atomic orbitals in the studied molecule have been obtained by analyzing the natural bonding orbitals.

Danilenko, T. N.; Tatevosyan, M. M.; Vlasenko, V. G.

2012-10-01

239

Experimental demonstration of femtosecond two-color x-ray free-electron lasers.  

PubMed

With an eye toward extending optical wave-mixing techniques to the x-ray regime, we present the first experimental demonstration of a two-color x-ray free-electron laser at the Linac Coherent Light Source. We combine the emittance-spoiler technique with a magnetic chicane in the undulator section to control the pulse duration and relative delay between two intense x-ray pulses and we use differently tuned canted pole undulators such that the two pulses have different wavelengths as well. Two schemes are shown to produce two-color soft x-ray pulses with a wavelength separation up to ?1.9% and a controllable relative delay up to 40 fs. PMID:23581326

Lutman, A A; Coffee, R; Ding, Y; Huang, Z; Krzywinski, J; Maxwell, T; Messerschmidt, M; Nuhn, H-D

2013-03-29

240

Experimental Demonstration of Femtosecond Two-Color X-Ray Free-Electron Lasers  

NASA Astrophysics Data System (ADS)

With an eye toward extending optical wave-mixing techniques to the x-ray regime, we present the first experimental demonstration of a two-color x-ray free-electron laser at the Linac Coherent Light Source. We combine the emittance-spoiler technique with a magnetic chicane in the undulator section to control the pulse duration and relative delay between two intense x-ray pulses and we use differently tuned canted pole undulators such that the two pulses have different wavelengths as well. Two schemes are shown to produce two-color soft x-ray pulses with a wavelength separation up to ˜1.9% and a controllable relative delay up to 40 fs.

Lutman, A. A.; Coffee, R.; Ding, Y.; Huang, Z.; Krzywinski, J.; Maxwell, T.; Messerschmidt, M.; Nuhn, H.-D.

2013-03-01

241

Achieving few-femtosecond time-sorting at hard X-ray free-electron lasers  

NASA Astrophysics Data System (ADS)

Recently, few-femtosecond pulses have become available at hard X-ray free-electron lasers. Coupled with the available sub-10 fs optical pulses, investigations into few-femtosecond dynamics are not far off. However, achieving sufficient synchronization between optical lasers and X-ray pulses continues to be challenging. We report a `measure-and-sort' approach, which achieves sub-10 fs root-mean-squared (r.m.s.) error measurement at hard X-ray FELs, far beyond the 100-200 fs r.m.s. jitter limitations. This timing diagnostic, now routinely available at the Linac Coherent Light Source (LCLS), is based on ultrafast free-carrier generation in optically transparent materials. Correlation between two independent measurements enables unambiguous demonstration of ~6 fs r.m.s. error in reporting the optical/X-ray delay, with single shot error suggesting the possibility of reaching few-femtosecond resolution.

Harmand, M.; Coffee, R.; Bionta, M. R.; Chollet, M.; French, D.; Zhu, D.; Fritz, D. M.; Lemke, H. T.; Medvedev, N.; Ziaja, B.; Toleikis, S.; Cammarata, M.

2013-03-01

242

X-Ray Radiation from Nonlinear Thomson Scattering of an Intense Femtosecond Laser on Relativistic Electrons in a Helium Plasma  

E-print Network

X-Ray Radiation from Nonlinear Thomson Scattering of an Intense Femtosecond Laser on Relativistic November 2003) We have generated x-ray radiation from the nonlinear Thomson scattering of a 30 fs=1:5 J laser beam on plasma electrons. A collimated x-ray radiation with a broad continuous spectrum peaked

Umstadter, Donald

243

Three-dimensional structure determination protocol for noncrystalline biomolecules using x-ray free-electron laser diffraction imaging.  

PubMed

Coherent and intense x-ray pulses generated by x-ray free-electron laser (XFEL) sources are paving the way for structural determination of noncrystalline biomolecules. However, due to the small scattering cross section of electrons for x rays, the available incident x-ray intensity of XFEL sources, which is currently in the range of 10(12)-10(13) photons/?m(2)/pulse, is lower than that necessary to perform single-molecule diffraction experiments for noncrystalline biomolecules even with the molecular masses of megadalton and submicrometer dimensions. Here, we propose an experimental protocol and analysis method for visualizing the structure of those biomolecules by the combined application of coherent x-ray diffraction imaging and three-dimensional reconstruction methods. To compensate the small scattering cross section of biomolecules, in our protocol, a thin vitreous ice plate containing several hundred biomolecules/?m(2) is used as sample, a setup similar to that utilized by single-molecule cryoelectron microscopy. The scattering cross section of such an ice plate is far larger than that of a single particle. The images of biomolecules contained within irradiated areas are then retrieved from each diffraction pattern, and finally provide the three-dimensional electron density model. A realistic atomic simulation using large-scale computations proposed that the three-dimensional structure determination of the 50S ribosomal subunit embedded in a vitreous ice plate is possible at a resolution of 0.8 nm when an x-ray beam of 10(16) photons/500×500 nm(2)/pulse is available. PMID:23496553

Oroguchi, Tomotaka; Nakasako, Masayoshi

2013-02-01

244

Field-emission scanning electron microscopy and energy-dispersive x-ray analysis to understand the role of tannin-based dyes in the degradation of historical wool textiles.  

PubMed

An innovative approach, combining field-emission scanning electron microscopy (FESEM) with energy dispersive X-ray spectroscopy (EDX) analysis, is presented to investigate the degradation mechanisms affecting tannin-dyed wool. In fact, tannin-dyed textiles are more sensitive to degradation then those dyed with other dyestuffs, even in the same conservation conditions. FESEM-EDX was first used to study a set of 48 wool specimens (artificially aged) dyed with several raw materials and mordants, and prepared according to historical dyeing recipes. EDX analysis was performed on the surface of wool threads and on their cross-sections. In addition, in order to validate the model formulated by the analysis of reference materials, several samples collected from historical and archaeological textiles were subjected to FESEM-EDX analysis. FESEM-EDX investigations enabled us to reveal the correlation between elemental composition and morphological changes. In addition, aging processes were clarified by studying changes in the elemental composition of wool from the protective cuticle to the fiber core in cross-sections. Morphological and elemental analysis of wool specimens and of archaeological and historical textiles showed that the presence of tannins increases wool damage, primarily by causing a sulfur decrease and fiber oxidation. PMID:24983911

Restivo, Annalaura; Degano, Ilaria; Ribechini, Erika; Pérez-Arantegui, Josefina; Colombini, Maria Perla

2014-10-01

245

Impulsive solar X-ray bursts: Bremsstrahlung radiation from a beam of electrons in the solar chromosphere and the total energy of solar flares  

NASA Technical Reports Server (NTRS)

Analysis of various aspects of impulsive X-ray bursts (IXB's) has lead to the consideration of a model where the X-rays are produced by bremsstrahlung radiation from a beam of electrons directed toward the photosphere. It was found that in general the X-ray spectrum from such a beam will fall off more rapidly than when the effect of the beaming of radiation is neglected. Furthermore, the spectral index of the resulting X-rays appears to increase by about unity for X-ray energies 100 kev, a fact which may explain the observed cutoff in the spectrum of the IXB's. It is also shown that in such a model there is sufficient energy in the form of nonthermal electrons to explain the total energy (approximately 10 to the 32nd power ergs) of a flare.

Petrosian, V.

1973-01-01

246

Internal conversion in energy dispersive X-ray analysis of actinide-containing materials.  

PubMed

The use of X-ray elemental analysis tools like energy dispersive X-ray (EDS) is described in the context of the investigation of nuclear materials. These materials contain radioactive elements, particularly alpha-decaying actinides that affect the quantitative EDS measurement by producing interferences in the X-ray spectra. These interferences originating from X-ray emission are the result of internal conversion by the daughter atoms from the alpha-decaying actinides. The strong interferences affect primarily the L X-ray lines from the actinides (in the typical energy range used for EDS analysis) and would require the use of the M lines. However, it is typically at the energy of the actinide's M lines that the interferences are dominant. The artifacts produced in the X-ray analysis are described and illustrated by some typical examples of analysis of actinide-bearing material. PMID:17490502

Wiss, Thierry; Thiele, Hartmut; Cremer, Bert; Ray, Ian

2007-06-01

247

Infrared Line Emission from Molecular Gas Heated by X-Rays and Energetic Electrons  

NASA Technical Reports Server (NTRS)

"I propose to carry out a detailed study using infrared observations (and in some cases, optical and ultraviolet observations) of dense interstellar gas exposed to intense fluxes of X-rays and/or energetic electrons. This is undoubtedly the dominant source of line emission for clouds exposed to X-rays from active galactic nuclei, supernova shocks, or embedded X-ray sources (e.g., X-ray binaries), or to high-temperature or relativistic electrons in galaxy clusters, near powerful radio sources, or supernova remnants. Detailed physical and chemical models of such clouds will be used to analyze infrared observations of the Great Annihilator X-ray source in the Galactic Center, cD galaxies in massive cooling flows, and the nuclei of Seyfert galaxies which will be obtained with the Infrared Space Observatory (ISO), UV and optical observations of the Crab Nebula obtained with the Hubble Space Telescope, and ground-based near-infrared observations of Seyfert nuclei. Results from this work will also be of great relevance to observations obtained with the Submillimeter Wave Astronomical Satellite (SWAS). In the first year of funding of this proposal, my chief collaborators (D.J. Hollenbach and A.G.G.M. Tielens, both of NASA Ames Research Center) and I concentrated on completing our models of the physical conditions in, and the resulting line emission from, dense gas irradiated by X-rays. As noted in the original proposal, some important physical processes were not yet thoroughly incorporated into our models at the time of submission. We completed our modeling of the physical conditions and line emission for essentially the entire range of parameter space (five orders of magnitude in X-ray flux to gas density ratio) occupied by typical dense interstellar clouds in which the gas is mostly neutral and X-rays are important for the ionization, chemistry, and thermal balance.

Maloney, Philip R.

1997-01-01

248

Direct observation of unstained wet biological samples by scanning-electron generation X-ray microscopy  

SciTech Connect

Analytical tools of nanometre-scale resolution are indispensable in the fields of biology, physics and chemistry. One suitable tool, the soft X-ray microscope, provides high spatial resolution of visible light for wet specimens. For biological specimens, X-rays of water-window wavelength between carbon (284 eV; 4.3 nm) and oxygen (540 eV; 2.3 nm) absorption edges provide high-contrast imaging of biological samples in water. Among types of X-ray microscope, the transmission X-ray microscope using a synchrotron radiation source with diffractive zone plates offers the highest spatial resolution, approaching 15-10 nm. However, even higher resolution is required to measure proteins and protein complexes in biological specimens; therefore, a new type of X-ray microscope with higher resolution that uses a simple light source is desirable. Here we report a novel scanning-electron generation X-ray microscope (SGXM) that demonstrates direct imaging of unstained wet biological specimens. We deposited wet yeasts in the space between two silicon nitride (Si{sub 3}N{sub 4}) films. A scanning electron beam of accelerating voltage 5 keV and current 1.6 nA irradiates the titanium (Ti)-coated Si{sub 3}N{sub 4} film, and the soft X-ray signal from it is detected by an X-ray photodiode (PD) placed below the sample. The SGXM can theoretically achieve better than 5 nm resolution. Our method can be utilized easily for various wet biological samples of bacteria, viruses, and protein complexes.

Ogura, Toshihiko, E-mail: t-ogura@aist.go.jp [Neuroscience Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, Umezono, Tsukuba, Ibaraki 305-8568 (Japan)] [Neuroscience Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, Umezono, Tsukuba, Ibaraki 305-8568 (Japan)

2010-01-01

249

X-ray photoemission electron microscopy for the study of semiconductor materials  

SciTech Connect

Photoemission Electron Microscopy (PEEM) using X-rays is a novel combination of two established materials analysis techniques--PEEM using UV light, and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. This combination allows the study of elemental composition and bonding structure of the sample by NEXAFS spectroscopy with a high spatial resolution given by the microscope. A simple, two lens, 10 kV operation voltage PEEM has been used at the Stanford Synchrotron Radiation Laboratory and at the Advanced Light Source (ALS) in Berkeley to study various problems including materials of interest for the semiconductor industry. In the present paper the authors give a short overview over the method and the instrument which was used, and describe in detail a number of applications. These applications include the study of the different phases of titanium disilicide, various phases of boron nitride, and the analysis of small particles. A brief outlook is given on possible new fields of application of the PEEM technique, and the development of new PEEM instruments.

Anders, S.; Stammler, T.; Padmore, H. [Lawrence Berkeley National Lab., CA (United States). Advanced Light Source Div.; Terminello, L.J.; Jankowski, A.F. [Lawrence Livermore National Lab., CA (United States); Stohr, J. [IBM Almaden Research Center, San Jose, CA (United States); Diaz, J. [Univ. de Oviedo (Spain). Dept. de Fisica; Cossy-Gantner, A. [EMPA, Duebendorf (Germany)

1998-03-01

250

X-ray photoemission electron microscopy for the study of semiconductor materials  

SciTech Connect

Photoemission Electron Microscopy using X-rays (X-PEEM) is a novel combination of two established materials analysis techniques{emdash}PEEM using UV light, and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. This combination allows the study of elemental composition and bonding structure of the sample by NEXAFS spectroscopy with a high spatial resolution given by the microscope. A simple, two lens, 10 kV operation voltage PEEM has been used at the Stanford Synchrotron Radiation Laboratory and at the Advanced Light Source (ALS) in Berkeley to study various problems including materials of interest for the semiconductor industry. In the present paper we give a short overview over the method and the instrument which was used, and describe in detail a number of applications. These applications include the study of the different phases of titanium disilicide, various phases of boron nitride, and the analysis of small particles. A brief outlook is given on possible new fields of application of the PEEM technique, and the development of new PEEM instruments. {copyright} {ital 1998 American Institute of Physics.}

Anders, S.; Stammler, T.; Padmore, H.A. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States); Terminello, L.J.; Jankowski, A.F. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94550 (United States); Stoehr, J. [IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120 (United States); Diaz, J. [Departamento de Fisic, Facultad de Ciencias, Universidad de Oviedo, Avda. Calvo Sotelo s/n, Oviedo, 33007 (Spain); Cossy-Favre, A. [EMPA, Duebendorf, Ueberlandstrasse 129, 8600 Duebendorf (Switzerland); Singh, S. [Center for X-ray Lithography, University of Wisconsin-Madison, Stoughton, Wisconsin 53589 (United States)

1998-11-01

251

X-ray photoemission electron microscopy for the study of semiconductor materials  

SciTech Connect

Photoemission Electron Microscopy using X-rays (X-PEEM) is a novel combination of two established materials analysis techniques--PEEM using UV light, and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. This combination allows the study of elemental composition and bonding structure of the sample by NEXAFS spectroscopy with a high spatial resolution given by the microscope. A simple, two lens, 10 kV operation voltage PEEM has been used at the Stanford Synchrotron Radiation Laboratory and at the Advanced Light Source (ALS) in Berkeley to study various problems including materials of interest for the semiconductor industry. In the present paper we give a short overview over the method and the instrument which was used, and describe in detail a number of applications. These applications include the study of the different phases of titanium disilicide, various phases of boron nitride, and the analysis of small particles. A brief outlook is given on possible new fields of application of the PEEM technique, and the development of new PEEM instruments.

Anders, Simone; Stammler, Thomas; Padmore, Howard A. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States); Terminello, Louis J.; Jankowski, Alan F. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94550 (United States); Stoehr, Joachim [IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120 (United States); Diaz, Javier [Departamento de Fisic, Facultad de Ciencias, Universidad de Oviedo, Avda. Calvo Sotelo s/n, Oviedo, 33007 (Spain); Cossy-Favre, Aline [EMPA, Duebendorf, Ueberlandstrasse 129, 8600 Duebendorf (Switzerland); Singh, Sangeet [Center for X-ray Lithography, University of Wisconsin-Madison, Stoughton, Wisconsin 53589 (United States)

1998-11-24

252

Clinical applications of scanning electron microscopy and X-ray microanalysis in dermatology  

SciTech Connect

Scanning electron microscopy is frequently applied to dermatological problems, as is evident from a review of the recent literature. In this paper, preparation methods and new techniques allowing experimental studies on the integumentary system are emphasized. Quantitative analysis in the electron microscope by use of energy-dispersive X-ray microanalysis (EDX) has become an important accessory technique. EDX can, for instance, be used to study problems involving physiological changes induced in skin by agents causing contact reactions. Recently, it has been shown that treatment with DNCB, chromate and nickel causes changes in elemental distribution in guinea-pig skin. In addition, elemental uptake in the integumentary system and in pathological inclusions in skin can be analyzed.

Forslind, B.

1984-01-01

253

Femtosecond X-ray Pulse Temporal Characterization in Free-Electron Lasers Using a Transverse Deflector  

SciTech Connect

We propose a novel method to characterize the temporal duration and shape of femtosecond x-ray pulses in a free-electron laser (FEL) by measuring the time-resolved electron-beam energy loss and energy spread induced by the FEL process, with a transverse radio-frequency deflector located after the undulator. Its merits are simplicity, high resolution, wide diagnostic range, and non-invasive to user operation. When the system is applied to the Linac Coherent Light Source, the first hard x-ray free-electron laser in the world, it can provide single-shot measurements on the electron beam and x-ray pulses with a resolution on the order of 1-2 femtoseconds rms.

Ding, Y.; /SLAC; Behrens, C.; /DESY; Emma, P.; Frisch, J.; Huang, Z.; Loos, H.; Krejcik, P.; Wang, M-H.; /SLAC

2011-12-13

254

Deep inner-shell multiphoton ionization by intense x-ray free-electron laser pulses.  

PubMed

We have investigated multiphoton multiple ionization dynamics of xenon atoms using a new x-ray free-electron laser facility, SPring-8 Angstrom Compact free electron LAser (SACLA) in Japan, and identified that Xe(n+) with n up to 26 is produced at a photon energy of 5.5 keV. The observed high charge states (n?24) are produced via five-photon absorption, evidencing the occurrence of multiphoton absorption involving deep inner shells. A newly developed theoretical model, which shows good agreement with the experiment, elucidates the complex pathways of sequential electronic decay cascades accessible in heavy atoms. The present study of heavy-atom ionization dynamics in high-intensity hard-x-ray pulses makes a step forward towards molecular structure determination with x-ray free-electron lasers. PMID:23679721

Fukuzawa, H; Son, S-K; Motomura, K; Mondal, S; Nagaya, K; Wada, S; Liu, X-J; Feifel, R; Tachibana, T; Ito, Y; Kimura, M; Sakai, T; Matsunami, K; Hayashita, H; Kajikawa, J; Johnsson, P; Siano, M; Kukk, E; Rudek, B; Erk, B; Foucar, L; Robert, E; Miron, C; Tono, K; Inubushi, Y; Hatsui, T; Yabashi, M; Yao, M; Santra, R; Ueda, K

2013-04-26

255

High-gain X-ray free electron laser by beat-wave terahertz undulator  

SciTech Connect

The THz undulator has a higher gain to realize a much brighter X-ray at saturation, compared with the optical undulator under the same undulator strength and beam quality. In order to fill the high-power THz gap and realize the THz undulator, two superimposed laser pulses at normal incidence to the electron-beam moving direction form an equivalent high-field THz undulator by the frequency difference to realize the high-gain X-ray Free electron laser. The pulse front tilt of lateral fed lasers is used to realize the electron-laser synchronic interaction. By PIC simulation, a higher gain and a larger X-ray radiation power by the beat wave THz undulator could be realized, compared with the optical undulator for the same electron beam parameters.

Chang, Chao; Hei, DongWei [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an City 710024 (China) [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an City 710024 (China); Institute of Energy, Tsinghua University, Beijing 100084 (China); Pellegrin, Claudio; Tantawi, Sami [SLAC National Accelerator Laboratory, Stanford University, Stanford, California 94309 (United States)] [SLAC National Accelerator Laboratory, Stanford University, Stanford, California 94309 (United States)

2013-12-15

256

Probing Bulk Electronic Structure with Hard X-ray Angle-Resolved Photoemission  

NASA Astrophysics Data System (ADS)

Traditional ultraviolet and soft x-ray angle-resolved photoemission spectroscopy (ARPES) may in some cases be too strongly influenced by surface effects to be a useful probe of bulk electronic structure. Going to hard x-ray photon energies and thus larger electron inelastic mean-free paths should provide a more accurate picture of bulk electronic structure. I will present the first experimental data for hard x-ray ARPES (HARPES) at energies of 3.2 and 6.0 keV. The systems discussed are W, as a model transition-metal system to illustrate basic principles, and (Ga,Mn)As, as a technologically-relevant ferromagnetic semiconductor material to illustrate the potential broad applicability of this new technique. The experimental results are compared to free-electron final-state model calculations and more precise one-step photoemission theory including matrix element effects. Some likely future applications areas are discussed.

Gray, Alexander; Minar, Jan; Ueda, Shigenori; Braun, Juergen; Ebert, Hubert; Dubon, Oscar; Kobayashi, Keisuke; Fadley, Charles

2011-11-01

257

X-ray diagnostics of runaway electrons generated during nanosecond discharge in gas at elevated pressures  

SciTech Connect

The properties of high-energy runaway electrons generated during a nanosecond discharge in an air filled diode at pressures up to 3 x 10{sup 5} Pa were studied using x-ray absorption spectroscopy. The results of studies of the discharge at different pressures and with different lengths of cathode-anode gap allow an insight into the factors that influence the energy distribution of runaway electrons. Energy distribution functions for runaway electrons produced in particle-in-cell simulation were used to create the x-ray attenuation curves via a computer-assisted technique simulating the generation of x-ray by energetic electrons. The simulated attenuation curves were compared to experimental results.

Yatom, S.; Levko, D.; Gleizer, J. Z.; Vekselman, V.; Krasik, Ya. E. [Physics Department, Technion, Haifa 32000 (Israel)

2012-01-09

258

A statistical analysis of hard X-Ray solar flares  

NASA Technical Reports Server (NTRS)

In this study we perform a statistical study on, 8319 X-Ray solar flares observed with the Hard X-Ray Spectrometer (HXRBS) on the Solar Maximum Mission satellite (SMM). The events are examined in terms of the durations, maximum intensities, and intensity profiles. It is concluded that there is no evidence for a correlation between flare intensity, flare duration, and flare asymmetry. However, we do find evidence for a rapid fall-of in the number of short-duration events.

Pearce, G.; Rowe, A. K.; Yeung, J.

1993-01-01

259

Solid and liquid spectroscopic analysis (SALSA) - A soft x-ray spectroscopy end station with a novel flow-through liquid cell  

E-print Network

art electron spectrometer. After describing the liquid cellflow-through liquid cell (Fig. 3b). Furthermore, an electronliquid cell and analysis chamber, 4: micrometer x-y-z precision stage, 5: VLS soft x-ray spectrometer, and 6: electron

Blum, M.

2010-01-01

260

TOPICAL REVIEW Quantitative strain analysis of surfaces and interfaces using extremely asymmetric x-ray diffraction  

NASA Astrophysics Data System (ADS)

Strain can reduce carrier mobility and the reliability of electronic devices and affect the growth mode of thin films and the stability of nanometer-scale crystals. To control lattice strain, a technique for measuring the minute lattice strain at surfaces and interfaces is needed. Recently, an extremely asymmetric x-ray diffraction method has been developed for this purpose. By employing Darwin's dynamical x-ray diffraction theory, quantitative evaluation of strain at surfaces and interfaces becomes possible. In this paper, we review our quantitative strain analysis studies on native SiO2/Si interfaces, reconstructed Si surfaces, Ni/Si(111)-H interfaces, sputtered III-V compound semiconductor surfaces, high-k/Si interfaces, and Au ion-implanted Si.

Akimoto, Koichi; Emoto, Takashi

2010-12-01

261

Crystallization and preliminary X-ray crystallographic analysis of importin-? from Neurospora crassa.  

PubMed

Importin-? recognizes cargo proteins that contain classical nuclear localization sequences (NLS) and, in complex with importin-?, is able to translocate nuclear proteins through the nuclear pore complex. The filamentous fungus Neurospora crassa is a well studied organism that has been widely used as a model organism for fundamental aspects of eukaryotic biology, and is important for understanding the specific mechanisms of protein transport to the cell nucleus. In this work, the crystallization and preliminary X-ray diffraction analysis of importin-? from N. crassa (IMP?-Nc) complexed with a classical NLS peptide (SV40 NLS) are reported. IMP?-Nc-SV40 NLS crystals diffracted X-rays to 2.0?Å resolution and the structure was solved by molecular-replacement techniques, leading to a monomeric structure. The observation of the electron-density map indicated the presence of SV40 NLSs interacting at both the minor and major NLS-binding sites of the protein. PMID:24699749

Bernardes, Natalia E; Takeda, Agnes A S; Freitas, Fernanda Z; Bertolini, Maria Célia; Fontes, Marcos R M

2014-04-01

262

High-Performance X-ray Detection in a New Analytical Electron Microscope  

NASA Technical Reports Server (NTRS)

X-ray detection by energy-dispersive spectrometry in the analytical electron microscope (AEM) is often limited by low collected X-ray intensity (P), modest peak-to-background (P/B) ratios, and limitations on total counting time (tau) due to specimen drift and contamination. A new AFM has been designed with maximization of P. P/B, and tau as the primary considerations. Maximization of P has been accomplished by employing a field-emission electron gun, X-ray detectors with high collection angles, high-speed beam blanking to allow only one photon into the detector at a time, and simultaneous collection from two detectors. P/B has been maximized by reducing extraneous background signals generated at the specimen holder, the polepieces and the detector collimator. The maximum practical tau has been increased by reducing specimen contamination and employing electronic drift correction. Performance improvments have been measured using the NIST standard Cr thin film. The 0-3 steradian solid angle of X-ray collection is the highest value available. The beam blanking scheme for X-ray detection provides 3-4 times greater throughput of X-rays at high count rates into a recorded spectrum than normal systems employing pulse-pileup rejection circuits. Simultaneous X-ray collection from two detectors allows the highest X-ray intensity yet recorded to be collected from the NIST Cr thin film. The measured P/B of 6300 is the highest level recorded for an AEM. In addition to collected X-ray intensity (cps/nA) and P/B measured on the standard Cr film, the product of these can be used as a figure-of-merit to evaluate instruments. Estimated minimum mass fraction (MMF) for Cr measured on the standard NIST Cr thin film is also proposed as a figure-of-merit for comparing X-ray detection in AEMs. Determinations here of the MMF of Cr detectable show at least a threefold improvement over previous instruments.

Lyman, C. E.; Goldstein, J. I.; Williams, D. B.; Ackland, D. W.; vonHarrach, S.; Nicholls, A. W.; Statham, P. J.

1994-01-01

263

Efficiency calibration of an HPGe X-ray detector for quantitative PIXE analysis  

NASA Astrophysics Data System (ADS)

Particle Induced X-ray Emission (PIXE) is an analytical technique, which provides reliably and accurately quantitative results without the need of standards when the efficiency of the X-ray detection system is calibrated. The ion beam microprobe of the Ion Beam Modification and Analysis Laboratory at the University of North Texas is equipped with a 100 mm2 high purity germanium X-ray detector (Canberra GUL0110 Ultra-LEGe). In order to calibrate the efficiency of the detector for standard less PIXE analysis we have measured the X-ray yield of a set of commercially available X-ray fluorescence standards. The set contained elements from low atomic number Z = 11 (sodium) to higher atomic numbers to cover the X-ray energy region from 1.25 keV to about 20 keV where the detector is most efficient. The effective charge was obtained from the proton backscattering yield of a calibrated particle detector.

Mulware, Stephen J.; Baxley, Jacob D.; Rout, Bibhudutta; Reinert, Tilo

2014-08-01

264

Prospects for the diagnosis of electron–ion temperature equilibration rates of warm dense matter by ultra-short pulse hard X-ray diffraction with an X-ray free electron laser  

Microsoft Academic Search

Ultra-short pulse kiloelectronvolt X-ray diffraction with an X-ray free electron laser and its potential for the diagnosis of electron–ion equilibration rates of warm dense matter are evaluated. A simple experimental configuration is suggested for the generation and subsequent probing of warm dense aluminium with the TESLA X-ray free electron laser. Differential scattering cross-sections are computed in an approximate manner with

J. J. Angulo Gareta; D. Riley

2006-01-01

265

Femtosecond x-ray pulse temporal characterization in free-electron lasers using a transverse deflector  

NASA Astrophysics Data System (ADS)

We propose a novel method to characterize the temporal duration and shape of femtosecond x-ray pulses in a free-electron laser (FEL) by measuring the time-resolved electron-beam energy loss and energy spread induced by the FEL process, with a transverse radio-frequency deflector located after the undulator. Its merits are simplicity, high resolution, wide diagnostic range, and noninvasive to user operation. When the system is applied to the Linac Coherent Light Source, the world’s most powerful x-ray FEL, it can provide single-shot measurements of the electron-beam and x-ray pulses with a resolution on the order of 1-2 femtoseconds rms.

Ding, Y.; Behrens, C.; Emma, P.; Frisch, J.; Huang, Z.; Loos, H.; Krejcik, P.; Wang, M.-H.

2011-12-01

266

Thin-film thickness measurement using x-ray peak ratioing in the scanning electron microscope  

SciTech Connect

The procedure used to measure laser target film thickness using a scanning electron microscope is summarized. This method is generally applicable to any coating on any substrate as long as the electron energy is sufficient to penetrate the coating and the substrate produces an x-ray signal which can pass back through the coating and be detected. (MOW)

Elliott, N.E.; Anderson, W.E.; Archuleta, T.A.; Stupin, D.M.

1981-01-01

267

Design optimization for an X-ray free electron laser driven by SLAC linac  

Microsoft Academic Search

I present a design study for an X-ray Free Electron Laser (FEL) driven by the SLAC linac. The study assumes the FEL is based on Self-Amplified Spontaneous Emission (SASE) and lasing is achieved in a single pass of a high current, high brightness electron beam through a long wiggler. Following a brief review of the fundamentals of SASE, I provide

Ming Xie

1995-01-01

268

Study of runaway electrons with Hard X-ray spectrometry of tokamak plasmas  

NASA Astrophysics Data System (ADS)

Hard-X-ray spectrometry is a tool widely used for diagnostic of runaway electrons in existing tokamaks. In future machines, ITER and DEMO, HXR spectrometry will be useful providing information on runaway electron energy, runaway beam current and its profile during disruption.

Shevelev, A.; Kiptily, V.; Chugunov, I.; Khilkevitch, E.; Gin, D.; Doinikov, D.; Naidenov, V.; Plyusnin, V.; EFDA-JET contributors

2014-08-01

269

Extension of x-ray imaging linear systems analysis to detectors with energy discrimination capability  

Microsoft Academic Search

A figure of merit, the broad-spectrum generalized detective quantum efficiency, which describes the performance of digital detectors designed for broad-spectrum x-ray imaging is derived from linear response theory. This measure of the imaging efficacy of an x-ray sensor is obtained when detector contrast modulation in the domain of x-ray energy is introduced in the Fourier-based analysis of digital systems. A

Julien P. Marchal; Julien P

2005-01-01

270

Electron beam-based sources of ultrashort x-ray pulses.  

SciTech Connect

A review of various methods for generation of ultrashort x-ray pulses using relativistic electron beam from conventional accelerators is presented. Both spontaneous and coherent emission of electrons is considered. The importance of the time-resolved studies of matter at picosecond (ps), femtosecond (fs), and atttosecond (as) time scales using x-rays has been widely recognized including by award of a Nobel Prize in 1999 [Zewa]. Extensive reviews of scientific drivers can be found in [BES1, BES2, BES3, Lawr, Whit]. Several laser-based techniques have been used to generate ultrashort x-ray pulses including laser-driven plasmas [Murn, Alte, Risc, Rose, Zamp], high-order harmonic generation [Schn, Rund, Wang, Arpi], and laser-driven anode sources [Ande]. In addition, ultrafast streak-camera detectors have been applied at synchrotron sources to achieve temporal resolution on the picosecond time scale [Wulf, Lind1]. In this paper, we focus on a different group of techniques that are based on the use of the relativistic electron beam produced in conventional accelerators. In the first part we review several techniques that utilize spontaneous emission of electrons and show how solitary sub-ps x-ray pulses can be obtained at existing storage ring based synchrotron light sources and linacs. In the second part we consider coherent emission of electrons in the free-electron lasers (FELs) and review several techniques for a generation of solitary sub-fs x-ray pulses. Remarkably, the x-ray pulses that can be obtained with the FELs are not only significantly shorter than the ones considered in Part 1, but also carry more photons per pulse by many orders of magnitude.

Zholents, A.; Accelerator Systems Division (APS)

2010-09-30

271

Study of runaway electrons using dosimetry of hard x-ray radiations in Damavand tokamak.  

PubMed

In this work several studies have been conducted on hard x-ray emissions of Damavand tokamak based on radiation dosimetry using the Thermoluminescence method. The goal was to understand interactions of runaway electrons with plasma particles, vessel wall, and plasma facing components. Total of 354 GR-200 (LiF:Mg,Cu,P) thermoluminescence dosimeter (TLD) crystals have been placed on 118 points--three TLDs per point--to map hard x-ray radiation doses on the exterior of the vacuum vessel. Results show two distinctive levels of x-ray radiations doses on the exterior of the vessel. The low-dose area on which measured dose is about 0.5 mSv/shot. In the low-dose area there is no particular component inside the vessel. On the contrary, on high-dose area of the vessel, x-ray radiations dose exceeds 30 mSv/shot. The high-dose area coincides with the position of limiters, magnetic probe ducts, and vacuum vessel intersections. Among the high-dose areas, the highest level of dose is measured in the position of the limiter, which could be due to its direct contact with the plasma column and with runaway electrons. Direct collisions of runaway electrons with the vessel wall and plasma facing components make a major contribution for production of hard x-ray photons in Damavand tokamak. PMID:24880371

Rasouli, C; Pourshahab, B; Hosseini Pooya, S M; Orouji, T; Rasouli, H

2014-05-01

272

Study of runaway electrons using dosimetry of hard x-ray radiations in Damavand tokamak  

NASA Astrophysics Data System (ADS)

In this work several studies have been conducted on hard x-ray emissions of Damavand tokamak based on radiation dosimetry using the Thermoluminescence method. The goal was to understand interactions of runaway electrons with plasma particles, vessel wall, and plasma facing components. Total of 354 GR-200 (LiF:Mg,Cu,P) thermoluminescence dosimeter (TLD) crystals have been placed on 118 points - three TLDs per point - to map hard x-ray radiation doses on the exterior of the vacuum vessel. Results show two distinctive levels of x-ray radiations doses on the exterior of the vessel. The low-dose area on which measured dose is about 0.5 mSv/shot. In the low-dose area there is no particular component inside the vessel. On the contrary, on high-dose area of the vessel, x-ray radiations dose exceeds 30 mSv/shot. The high-dose area coincides with the position of limiters, magnetic probe ducts, and vacuum vessel intersections. Among the high-dose areas, the highest level of dose is measured in the position of the limiter, which could be due to its direct contact with the plasma column and with runaway electrons. Direct collisions of runaway electrons with the vessel wall and plasma facing components make a major contribution for production of hard x-ray photons in Damavand tokamak.

Rasouli, C.; Pourshahab, B.; Hosseini Pooya, S. M.; Orouji, T.; Rasouli, H.

2014-05-01

273

From Storage Rings to Free Electron Lasers for Hard X-Rays  

SciTech Connect

The intensity of X-ray sources has increased at a rapid rate since the late 1960s by 10 orders of magnitude and more through the use of synchrotron radiation produced by bending magnets, wigglers and undulators. Three generations of radiation sources have been identified depending on amplitude and quality of the radiation provided. While user facilities of the third generation were being constructed a new concept of radiation generating devices was being developed that offers an even larger increase in peak and average brightness than had been achieved till then. The new concept of the X-ray Free Electron Laser based on the principle of Self-Amplified Spontaneous Emission will be the basis of fourth generation X-ray source user facilities of this century. The paper will start with a brief history of the development of x-ray sources, discuss some of the differences between storage ring and free electron laser based approaches, and close with an update of the present development of x-ray free electron laser user facilities.

Nuhn, H

2004-01-09

274

Micro-column Scanning Electron Microscope and X-ray Spectrometer (MSEMS) for Planetary Exploration  

NASA Astrophysics Data System (ADS)

Scanning Electron Microscopy combined with electron-induced X-ray Fluorescence Spectroscopy (SEM-EDX) is one of the most powerful techniques for characterizing sub-µm surface morphology and composition. In terrestrial laboratories, SEM-EDX is used to elucidate natural processes such as low-temperature diagenesis, thermal or pressure induced metamorphism, volcanism/magmatism, atmosphere/crust interaction and biological activity. Such information would be highly useful for investigating the natural history of the terrestrial planets, satellites and primitive bodies, providing morphological and elemental information that is 2 orders of magnitude higher in resolution than optical techniques. Below we describe the development of a Micro-column Scanning Electron Microscope and X-ray Spectrometer (MSEMS) for flight. The enabling technology of the MSEMS is a carbon nanotube field emission (CNTFE) electron source that is integrated with micro-electro-mechanical-systems (MEMS) - based electron gun and electron optical structures. A hallmark of CNTFE electron sources is their low chromatic aberration, which reduces the need for high accelerating voltages to obtain small spot size. The CNTFE also offers exceptional brightness and nanometer source size, eliminating the need for condenser lenses, making simple electrostatic focusing optics possible. Moreover, the CNT field emission gun (CFEG) at low operating voltage dissipates 103 less power than thermally-assisted Schottky emitters. A key feature of the MSEMS design is the lack of scanning coils. Rather, a piezoelectric sample stage capable of sub-nanometer resolution scans the sample past the fixed crossover of the MSEMS electron beam. We will describe a MEMS-based templating technique for fabricating mechanically and electrically stable miniature CFEGs. Using existing silicon (Si) technology, we fabricated highly controlled and precise MEMS structures for both the CNT cathode and focusing optics for the micro-column. The reproducibility of anisotropic wet etching enables precise alignment of the CNT tip with the electron extracting first anode in a gun configuration by using an interlocking templating technique. The CFEG can be fully integrated with a MEMS-based microcolumn. Extensive electron trajectory analysis using Lorentz 2D/3D software demonstrates that 10-nm imaging resolution at 5 keV is achievable with a 10-mm working distance from a column measuring just 16 mm in length. We will present the design of the microcolumn as well as the MEMS fabrication process. We have also tested a piezoelectric scanning stage inside a laboratory SEM with a fixed electron beam. Additional, we implemented our own LabVIEW software interface for controlling the stage and for enabling communication with the secondary electron detector for image formation. SEM micrographs obtained employing this novel technique will be presented.

Ribaya, B.; Niemann, D.; Makarewicz, J.; Clevenson, H.; McKenzie, C.; Nguyen, C.; Blake, D. F.

2009-12-01

275

Scale analysis using X-ray microfluorescence and computed radiography  

NASA Astrophysics Data System (ADS)

Scale deposits are the most common and most troublesome damage problems in the oil field and can occur in both production and injection wells. They occur because the minerals in produced water exceed their saturation limit as temperatures and pressures change. Scale can vary in appearance from hard crystalline material to soft, friable material and the deposits can contain other minerals and impurities such as paraffin, salt and iron. In severe conditions, scale creates a significant restriction, or even a plug, in the production tubing. This study was conducted to qualify the elements present in scale samples and quantify the thickness of the scale layer using synchrotron radiation micro-X-ray fluorescence (SR?XRF) and computed radiography (CR) techniques. The SR?XRF results showed that the elements found in the scale samples were strontium, barium, calcium, chromium, sulfur and iron. The CR analysis showed that the thickness of the scale layer was identified and quantified with accuracy. These results can help in the decision making about removing the deposited scale.

Candeias, J. P.; de Oliveira, D. F.; dos Anjos, M. J.; Lopes, R. T.

2014-02-01

276

A 9 keV electron-impact liquid-gallium-jet x-ray source  

Microsoft Academic Search

We demonstrate a high-brightness compact 9 keV electron-impact microfocus x-ray source based on a liquid-gallium-jet anode. A ~30 W, 50 kV electron gun is focused onto the ~20 m\\/s, 30 mum diameter liquid-gallium-jet anode to produce an ~10 mum full width at half maximum x-ray spot. The peak spectral brightness is >2×1010 photons\\/(s mm2 mrad2×0.1% BW). Calculation and experiments show

M. Otendal; T. Tuohimaa; U. Vogt; H. M. Hertz

2008-01-01

277

Analysis of particles produced during airbag deployment by scanning electron microscopy with energy dispersive x-ray spectroscopy and their deposition on surrounding surfaces: a mid-research summary  

NASA Astrophysics Data System (ADS)

Airbags can be encountered in forensic work when investigating a car crash and are typically constructed with primerlike material to begin the deployment apparatus. The mechanisms of airbag deployment can produce particles ideal for scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS) analysis. A recent study published by Berk studied airbags with vents and showed that it is possible for particles generated from the deployment of these airbags to deposit on surfaces in the vehicle as the airbags deflate.1 Another paper published by Berk reported particles similar in morphology and composition to primer gunshot residue (GSR) are produced by side impact airbags.2 This paper's aim will be to show mid-point results of a study still in progress in which non-vented airbags were analyzed to determine if they exhibited the same particle depositing features as their vented airbag counterparts. Further investigation in this study is being performed to find more airbags which produce primer gunshot residue-like particles containing lead, barium, and antimony from airbag deployment. To date, the study has resulted in (1) non-vented airbags exhibiting deposition of particles suitable for SEM/EDS analysis and (2) no gunshot residue-like particles being detected from the airbag residues studied thus far.

Wyatt, J. Matney

2011-06-01

278

Development of a new quantitative X-ray microanalysis method for electron microscopy.  

PubMed

Quantitative X-ray microanalysis of thick samples is usually performed by measuring the characteristic X-ray intensities of each element in a sample and in corresponding standards. The ratio of the measured intensities from the unknown material to that from the standard is related to the concentration using the ZAF or ?(?z) equations. Under optimal conditions, accuracies approaching 1% are possible. However, all the experimental conditions must remain the same during the sample and standard measurements. This is not possible with cold field emission scanning electron microscopes (FE-SEMs) where beam current can fluctuate around 5% in its stable regime. Very little work has been done on variable beam current conditions (Griffin, B.J. & Nockolds, C.E., Scanning 13, 307-312, 1991), and none relating to cold FE-SEM applications. To address this issue, a new method was developed using a single spectral measurement. It is similar in approach to the Cliff-Lorimer method developed for the analytical transmission electron microscope. However, corrections are made for X rays generated from thick specimens using the ratio of the characteristic X-ray intensities of two elements in the same material. The proposed method utilizes the ratio of the intensity of a characteristic X-ray normalized by the sum of X-ray intensities of all the elements measured for the sample, which should also reduce the amplitude of error propagation. Uncertainties in the physical parameters of X-ray generation are corrected using a calibration factor that must be previously acquired or calculated. As an example, when this method was applied to the calculation of the composition of Au-Cu National Institute of Standards and Technology standards measured with a cold field emission source SEM, relative accuracies better than 5% were obtained. PMID:20961482

Horny, Paula; Lifshin, Eric; Campbell, Helen; Gauvin, Raynald

2010-12-01

279

Quantitative x-ray diffraction phase analysis of coarse airborne particulate collected by cascade impactor sampling  

Microsoft Academic Search

Mineralogical composition of Castellon (Spanish Mediterranean coast) atmospheric aerosol was studied by X-ray diffraction by sampling with a cascade impactor without filters. Quantitative phase analysis of natural phases present in the atmospheric coarse aerosol was performed using a modified version of the computer program MENGE, that uses the standardless X-ray method developed by Rius for the quantitative analysis of multiphase

L. E. Ochando; J. M. Amigó

1997-01-01

280

Quantitative strain analysis of single crystals using x-ray topography  

Microsoft Academic Search

The x-ray topography technique images diffraction intensity variations of a crystal. The use of a CCD camera enables the measurement of different spatial resolutions. Currently an x-ray topograph with spatial resolution of 1 micron has been achieved, but the quantitative data analysis has not been explored widely. Quantitative strain analysis on these images extends new capabilities in crystal study. We

Y. Zhong; Y. S. Chu; A. T. Macrander; S. F. Krasnicki

2007-01-01

281

X-RAY DIFFRACTION PHASE ANALYSIS OF PROCESS AND POLLUTION CONTROL DEVICE SAMPLES  

EPA Science Inventory

The paper describes the application of x-ray diffraction (XRD) analysis to several samples which show the information available from the technique. X-ray fluorescence (XRF) spectrometry was used for the elemental analysis because it provides very complete information with minimal...

282

Simultaneous X-ray diffraction and differential thermal analysis of polymers  

Microsoft Academic Search

Simultaneous measurement of X-ray diffraction patterns and differential temperature curves is an excellent method to eliminate the disadvantages in common DSC analysis. Problems in DSC analysis of polymers include phenomena such as multiple melting and fractionated crystallization. By simultaneous registration of X-ray diffraction patterns the melting and crystallization peaks can be assigned to different phases in multiphase materials. A sample

R. Androsch; M. Stolp; H.-J. Radusch

1996-01-01

283

High-resolution X-ray imaging and analysis of coatings on and in wood  

E-print Network

performed on thermal barrier coatings,9 paper10,11 and cultural heritage.12 High-resolutiHigh-resolution X-ray imaging and analysis of coatings on and in wood 1 2 3 4 5 Jan Van den Bulcke1. High-resolution X- ray imaging and analysis of coatings on and in wood. Journal of Coatings Technology

Gent, Universiteit

284

Development of a micro-X-ray fluorescence system based on polycapillary X-ray optics for non-destructive analysis of archaeological objects  

NASA Astrophysics Data System (ADS)

A new micro-X-ray fluorescence (micro-XRF) system based on rotating anode X-ray generator and polycapillary X-ray optics has been set up in XOL Lab, BNU, China, in order to be used for analysis of archaeological objects. The polycapillary X-ray optics used here can focus the primary X-ray beam down to tens of micrometers in diameter that allows for non-destructive and local analysis of sub-mm samples with minor/trace level sensitivity. The analytical characteristics and potential of this micro-XRF system in archaeological research are discussed. Some described uses of this instrument include studying Chinese ancient porcelain.

Cheng, Lin; Ding, Xunliang; Liu, Zhiguo; Pan, Qiuli; Chu, Xuelian

2007-08-01

285

On line shape analysis in X-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

Any solid state X-ray photoelectron spectrum (XPS) contains contributions due to multiple inelastic scattering in the bulk, surface excitations, energy losses originating from the screening of the final state hole (intrinsic losses), and, for non-monochromatized incident radiation, ghost lines originating from the X-ray satellites. In the present paper it is shown how all these contributions can be consecutively removed from an experimental spectrum employing a single general deconvolution procedure. Application of this method is possible whenever the contributions mentioned above are uncorrelated. It is shown that this is usually true in XPS to a good approximation. The method is illustrated on experimental non-monochromatized MgK? spectra of Au acquired at different detection angles but for the same angle of incidence of the X-rays.

Werner, Wolfgang S. M.; Cabela, Thomas; Zemek, Josef; Jiricek, Petr

2001-01-01

286

X-ray Phase Contrast analysis - Digital wavefront development  

SciTech Connect

Optical schemes that enable imaging of the phase shift produced by an object have become popular in the x-ray region, where phase can be the dominant contrast mechanism. The propagation-based technique consists of recording the interference pattern produced by choosing one or several sample-to-detector distances. Pioneering studies, carried out making use of synchrotron radiation, demonstrated that this technique results in a dramatic increase of image contrast and detail visibility, allowing the detection of structures invisible with conventional techniques. An experimental and theoretical study of in-line hard x-ray phase-contrast imaging had been performed. The theoretical description of the technique is based on Fresnel diffraction. As an illustration of the potential of this quantitative imaging technique, high-resolution x-ray phase contrast images of simple objects will be presented.

Idir, Mourad [Metrology Beamline, Synchrotron SOLEIL, Gif-sur-Yvette (France); Potier, Jonathan [Phaseview, Palaiseau (France); Universite Paul Sabatier-Toulouse III, Metrology Beamline, Synchrotron SOLEIL, Gif-sur-Yvette (France); Fricker, Sebastien [Phaseview, Palaiseau (France); Snigirev, Anatoly; Snigireva, Irina [ESRF, Grenoble (France); Modi, M. H. [X-ray Optics Section, Raja Ramanna Centre for Advanced Technology, Indore (India)

2010-06-23

287

Towards Zeptosecond-Scale Pulses from X-Ray Free-Electron Lasers  

E-print Network

The short wavelength and high peak power of the present generation of free-electron lasers (FELs) opens the possibility of ultra-short pulses even surpassing the present (tens to hundreds of attoseconds) capabilities of other light sources - but only if x-ray FELs can be made to generate pulses consisting of just a few optical cycles. For hard x-ray operation (~0.1nm), this corresponds to durations of approximately a single attosecond, and below into the zeptosecond scale. This talk will describe a novel method to generate trains of few-cycle pulses, at GW peak powers, from existing x-ray FEL facilities by using a relatively short 'afterburner'. Such pulses would enhance research opportunity in atomic dynamics and push capability towards the investigation of electronic-nuclear and nuclear dynamics. The corresponding multi-colour spectral output, with a bandwidth envelope increased by up to two orders of magnitudes over SASE, also has potential applications.

Dunning, D J; Thompson, N R

2013-01-01

288

X-ray and electron response of 4H-SiC vertical interdigitated Schottky photodiodes  

NASA Astrophysics Data System (ADS)

We report on the X-ray and electron performance of a low voltage reverse biased 4H-SiC vertical Schottky photodiode, based on the pinch-off surface effect, obtained by means of self-aligned Nickel Silicide (Ni2Si) interdigitated contacts. Although these photodiodes were original designed for UV detection their open Schottky contact is attractive for soft X-ray and low energy electron detection. The open electrode structure of the device allows the incident radiation to reach the active layer with minimal absorption. The photon counting spectroscopy response for soft X-rays is reported and compared to those predicted from a Monte Carlo model for SiC devices. We also show these devices can detect beta particles from 3H and 14C radioisotope sources with a combined energy range 1-156 keV.

Lees, J. E.; Barnett, A. M.; Bassford, D. J.; Mazzillo, M.

2012-11-01

289

Morphological study of energetic electron precipitation events using the satellite bremsstrahlung X ray technique  

NASA Technical Reports Server (NTRS)

The precipitation of energetic electrons into the atmosphere is investigated with simultaneous measurements of bremsstrahlung X-rays, emitted from different local time sectors. The measurements were performed from the low-altitude, polar-orbiting satellite P78-1 with an array of X-ray spectrometers (21-139 keV). Magnetic local-time (MLT) profiles of the intensities and energy spectra were obtained for a broad span of L values. From approximately 0930 to 1400 MLT the average X-ray intensity was found to decrease with increasing magnetic local time, whereas from 2200 to 0200 MLT no clear trend with local time was observed. The data presented are noted to correspond closely with the relative electron precipitation (REP)-type events, though no evidence of a distinct group of REP was found.

Imhof, W. L.; Kilner, J. R.; Reagan, J. B.

1985-01-01

290

X-ray spectra and electronic structure of high T/sub c/ superconductors  

SciTech Connect

At the present moment spectral investigations have been done for two types of ceramic oxidic HTSC: La/sub 2-x/Sr/sub x/CuO/sub 4/ and YBa/sub 2/Cu/sub 3/O/sub 7/. These investigations had the following purposes: 1. Thorough investigation of energy band structure and distribution of partial densities of states of HTSC in a wide energy interval as well as experimental testing of band structure calculations. 2. Analysis of electron structure of HTSC on the surface and within the bulk. 3. Determination of the oxidation degree of constituent atoms in HTSC and, first of all, the presence of Cu/sup 3+/ ions, EXAFS and XANES studies of the short order in HTSC. Before discussing the obtained results the authors review briefly what information one can be obtained from X-ray and photoelectron spectra.

Kurmaev, E.Z.; Finkelstein, L.D.; Nefedov, V.I.

1988-08-01

291

A system for acquiring simultaneous electron energy-loss and X-ray spectrum-images.  

PubMed

A compositional imaging system based on simultaneous scanning electron energy-loss spectroscopy (EELS) and energy-dispersive X-ray spectroscopy (EDS) was developed. This system utilizes the combined power of EELS and EDS for quantitative compositional imaging at nanometre resolution. The system is particularly suitable for, but not limited to, biological research, as it simultaneously provides sensitive maps of an element such as Ca or P from EELS and of many other elements from EDS. Degradation of resolution by specimen drift is prevented by correcting for drift during data acquisition, using image cross-correlation. Several advanced features are implemented for real-time and/or off-line quantitative analysis, and the performance of the system is illustrated with practical applications to compositional imaging of cardiac muscle. PMID:15230880

Feng, J; Somlyo, A V; Somlyo, A P

2004-07-01

292

The application of photon, electron and proton induced X-ray analysis for the identification and characterisation of medieval silver coins  

NASA Astrophysics Data System (ADS)

Photons, electrons and protons beams applied to the scientific investigation of archaeological materials provide complementary information for characterising the state of preservation and the provenance of the objects. Investigations were carried out on medieval silver coins of the "Friesacher Pfennig" and the "Tiroler Kreuzer" from the Kunsthistorisches Museum Vienna and the Oesterreichische Nationalbank. Techniques employed were EDXRF, SEM/EDX and PIXE. By determining the trace elements of the alloys it was possible to assign coins to their mint. The results outline advantages and disadvantages of EDXRF, SEM/EDX and PIXE when applied to corroded objects.

Linke, R.; Schreiner, M.; Demortier, G.

2004-11-01

293

Resonance fluorescence in ultrafast and intense x-ray free-electron-laser pulses  

NASA Astrophysics Data System (ADS)

The spectrum of resonance fluorescence is calculated for a two-level system excited by an intense, ultrashort x-ray pulse made available, for instance, by free-electron lasers such as the Linac Coherent Light Source. We allow for inner-shell hole decay widths and destruction of the system by further photoionization. This two-level description is employed to model neon cations strongly driven by x rays tuned to the 1s2p-1?1s-12p transition at 848eV; the x rays induce Rabi oscillations which are so fast that they compete with Ne 1s-hole decay. We predict resonance fluorescence spectra for two different scenarios: first, chaotic pulses based on the self-amplified spontaneous emission principle, like those presently generated at x-ray free-electron-laser facilities and, second, Gaussian pulses which will become available in the foreseeable future with self-seeding techniques. As an example of the exciting opportunities derived from the use of seeding methods, we predict, in spite of the above obstacles, the possibility to distinguish at x-ray frequencies a clear signature of Rabi flopping in the spectrum of resonance fluorescence.

Cavaletto, Stefano M.; Buth, Christian; Harman, Zoltán; Kanter, Elliot P.; Southworth, Stephen H.; Young, Linda; Keitel, Christoph H.

2012-09-01

294

THE X-RAY DETECTABILITY OF ELECTRON BEAMS ESCAPING FROM THE SUN  

SciTech Connect

We study the detectability and characterization of electron beams as they leave their acceleration site in the low corona toward interplanetary space through their nonthermal X-ray bremsstrahlung emission. We demonstrate that the largest interplanetary electron beams ({approx}>10{sup 35} electrons above 10 keV) can be detected in X-rays with current and future instrumentation, such as RHESSI or the X-Ray Telescope (XRT) onboard Hinode. We make a list of optimal observing conditions and beam characteristics. Amongst others, good imaging (as opposed to mere localization or detection in spatially integrated data) is required for proper characterization, putting the requirement on the number of escaping electrons (above 10 keV) to {approx}>3 x 10{sup 36} for RHESSI, {approx}>3 x 10{sup 35} for Hinode/XRT, and {approx}>10{sup 33} electrons for the FOXSI sounding rocket scheduled to fly in 2011. Moreover, we have found that simple modeling hints at the possibility that coronal soft X-ray jets could be the result of local heating by propagating electron beams.

Saint-Hilaire, Pascal; Krucker, Saem; Christe, Steven; Lin, Robert P. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)], E-mail: shilaire@ssl.berkeley.edu

2009-05-01

295

Energy dispersive x-ray analysis in the study of pneumoconiosis.  

PubMed Central

Identification of inorganic substances in the lung is an important step towards the establishment of a cause and effect relationship in the study of pneumoconiosis. The conventional methods for this identification usually require an ashing which makes it difficult to study the localisation of these substances in relation to pathology. A method is described to identify foreign substances in the tissue obtained either on biopsy or autopsy without destroying them. The technique employs scanning electron microscopy together with energy dispersive x-ray analysis. This method not only allows simultaneous multi-elemental analysis of over 80 elements, but also permits detailed morphological examination while the tissue is being analysed. Images PMID:871449

Funahashi, A; Siegesmund, K A; Dragen, R F; Pintar, K

1977-01-01

296

Femtosecond x-ray pulse characterization in free-electron lasers using a cross-correlation technique.  

PubMed

We report the first measurements of x-ray single-pulse duration and two-pulse separation at the Linac Coherent Light Source using a cross-correlation technique involving x rays and electrons. An emittance-spoiling foil is adopted as a very simple and effective method to control the output x-ray pulse. A minimum pulse duration of about 3 fs full width at half maximum has been measured together with a controllable pulse separation (delay) between two pulses. This technique provides critical temporal diagnostics for x-ray experiments such as x-ray pump-probe studies. PMID:23368472

Ding, Y; Decker, F-J; Emma, P; Feng, C; Field, C; Frisch, J; Huang, Z; Krzywinski, J; Loos, H; Welch, J; Wu, J; Zhou, F

2012-12-21

297

Femtosecond X-Ray Pulse Characterization in Free-Electron Lasers Using a Cross-Correlation Technique  

NASA Astrophysics Data System (ADS)

We report the first measurements of x-ray single-pulse duration and two-pulse separation at the Linac Coherent Light Source using a cross-correlation technique involving x rays and electrons. An emittance-spoiling foil is adopted as a very simple and effective method to control the output x-ray pulse. A minimum pulse duration of about 3 fs full width at half maximum has been measured together with a controllable pulse separation (delay) between two pulses. This technique provides critical temporal diagnostics for x-ray experiments such as x-ray pump-probe studies.

Ding, Y.; Decker, F.-J.; Emma, P.; Feng, C.; Field, C.; Frisch, J.; Huang, Z.; Krzywinski, J.; Loos, H.; Welch, J.; Wu, J.; Zhou, F.

2012-12-01

298

The electronic structure of polyaniline and doped phases studied by soft X-ray absorption and emission spectroscopies  

E-print Network

The electronic structure of the conjugated polymer, polyaniline, has been studied by resonant and nonresonant X-ray emission spectroscopy using synchrotron radiation for the excitation. The measurements were made on polyaniline and a few doped (protonated) phases for both the carbon and nitrogen contents. The resonant X-ray emission spectra show depletion of the {\\pi} electron bands due to the selective excitation which enhances the effect of symmetry selection rules. The valence band structures in the X-ray emission spectra attributed to the {\\pi} bands show unambiguous changes of the electronic structure upon protonation. By comparing to X-ray absorption measurements, the chemical bonding and electronic configuration is characterized.

Magnuson, M; Butorin, S M; Agui, A; Såthe, C; Nordgren, J; Monkman, A P; 10.1063/1.479238

2012-01-01

299

Electron Spectroscopy: Ultraviolet and X-Ray Excitation.  

ERIC Educational Resources Information Center

Reviews recent growth in electron spectroscopy (54 papers cited). Emphasizes advances in instrumentation and interpretation (52); photoionization, cross-sections and angular distributions (22); studies of atoms and small molecules (35); transition, lanthanide and actinide metal complexes (50); organometallic (12) and inorganic compounds (2);…

Baker, A. D.; And Others

1980-01-01

300

Elemental composition of strawberry plants inoculated with the plant growth-promoting bacterium Azospirillum brasilense REC3, assessed with scanning electron microscopy and energy dispersive X-ray analysis.  

PubMed

The elemental composition of strawberry plants (Fragaria ananassa cv. Macarena) inoculated with the plant growth-promoting bacterium Azospirillum brasilense REC3, and non-inoculated controls, was studied using scanning electron microscopy (SEM) and energy dispersive X-ray (EDS) analysis. This allowed simultaneous semi-quantification of different elements in a small, solid sample. Plants were inoculated and grown hydroponically in 50% or 100% Hoagland solution, corresponding to limited or optimum nutrient medium, respectively. Bacteria-inoculated plants increased the growth index 45% and 80% compared to controls when grown in 100% and 50% Hoagland solution, respectively. Thus, inoculation with A. brasilense REC3 in a nutrient-limited medium had the strongest effect in terms of increasing both shoot and root biomass and growth index, as already described for Azospirillum inoculated into nutrient-poor soils. SEM-EDS spectra and maps showed the elemental composition and relative distribution of nutrients in strawberry tissues. Leaves contained C, O, N, Na, P, K, Ca and Cu, while roots also had Si and Cl. The organic fraction (C, O and N) accounted for over 96.3% of the total chemical composition; of the mineral fraction, Na had higher accumulation in both leaves and roots. Azospirillum-inoculated and control plants had similar elemental quantities; however, in bacteria-inoculated roots, P was significantly increased (34.33%), which constitutes a major benefit for plant nutrition, while Cu content decreased (35.16%). PMID:24148195

Guerrero-Molina, M F; Lovaisa, N C; Salazar, S M; Díaz-Ricci, J C; Pedraza, R O

2014-07-01

301

Challenges to quantitative multivariate statistical analysis of atomic-resolution X-ray spectral.  

PubMed

A new aberration-corrected scanning transmission electron microscope equipped with an array of Si-drift energy-dispersive X-ray spectrometers has been utilized to acquire spectral image data at atomic resolution. The resulting noisy data were subjected to multivariate statistical analysis to noise filter, remove an unwanted and partially overlapping non-sample-specific X-ray signal, and extract the relevant correlated X-ray signals (e.g., channels with L and K lines). As an example, the Y?Ti?O? pyrochlore-structured oxide (assumed here to be ideal) was interrogated at the [011] projection. In addition to pure columns of Y and Ti, at this projection, there are also mixed 50-50 at. % Y-Ti columns. An attempt at atomic-resolution quantification is presented. The method proposed here is to subtract the non-column-specific signal from the elemental components and then quantify the data based upon an internally derived k-factor. However, a theoretical basis to predict this non-column-specific signal is needed to make this generally applicable. PMID:22849798

Kotula, Paul G; Klenov, Dmitri O; von Harrach, H Sebastian

2012-08-01

302

X-ray analysis of fully depleted CCDs with small pixel size  

NASA Astrophysics Data System (ADS)

X-rays frames offer a lot of information about CCD. 55Fe sources are traditionally being used for CCD gain and charge transfer efficiency (CTE) measurements. The pixel size of modern scientific CCDs is getting smaller. The charge diffusion causes the charge spread among neighboring pixels especially in thick fully depleted sensors. This enables measurement of the charge diffusion using 55Fe X-rays. On the other hand, the usual CTE char- acterization method based on single pixel X-ray events becomes statistically deficient. A new way of measuring CTE using shape and amplitude analysis of X-ray clusters is presented and discussed. This method requires high statistical samples. Advances in test automation and express analysis technique allows for acquiring such statistical samples in a short period of time. The details of our measurement procedure are presented. The lateral diffusion measured using e2v CCD250 is presented and implications for X-ray cluster size and expected cluster shape are discussed. The CTE analysis using total X-ray cluster amplitude is presented. This analysis can reveal CTE problems for certain conditions. The statistical analysis of average X-ray cluster shape is presented. Characteristics X-rays can be used for the whole system absolute calibration. We demonstrate how spectral features of 55Fe and 241Am rad. sources are used for system linearity measurements.

Kotov, I. V.; Haupt, J.; Kubánek, P.; O'Connor, P.; Takacs, P.

2014-07-01

303

X-ray analysis of fully depleted CCDs with small pixel size  

NASA Astrophysics Data System (ADS)

X-rays frames offer a lot of information about CCD. 55Fe sources are traditionally being used for CCD gain and charge transfer efficiency (CTE) measurements. The pixel size of modern scientific CCDs is getting smaller. The charge diffusion causes the charge spread among neighboring pixels especially in thick fully depleted sensors. This enables measurement of the charge diffusion using 55Fe X-rays. On the other hand, the usual CTE char- acterization method based on single pixel X-ray events becomes statistically deficient. A new way of measuring CTE using shape and amplitude analysis of X-ray clusters is presented and discussed. This method requires high statistical samples. Advances in test automation and express analysis technique allows for acquiring such statistical samples in a short period of time. The details of our measurement procedure are presented. The lateral diffusion measured using e2v CCD250 is presented and implications for X-ray cluster size and expected cluster shape are discussed. The CTE analysis using total X-ray cluster amplitude is presented. This analysis can reveal CTE problems for certain conditions. The statistical analysis of average X-ray cluster shape is presented. Characteristics X-rays can be used for the whole system absolute calibration. We demonstrate how spectral features of 55Fe and 241Am rad. sources are used for system linearity measurements.

Kotov, I. V.; Haupt, J.; Kubánek, P.; O'Connor, P.; Takacs, P.

2013-07-01

304

X-ray irradiation induced changes in electron transport in stabilized a-Se photoconductors  

SciTech Connect

We have examined the effect of high-dose x-ray irradiation on electron transport in stabilized amorphous selenium (a-Se) x-ray photoconductive films (of the type used in x-ray image detectors) by measuring the electron lifetime ?{sub e} through interrupted-field time-of-flight experiments. X-ray induced effects have been examined through two types of experiments. In recovery experiments, the a-Se was preirradiated with and without an applied field (5 V/?m) during irradiation with sufficient dose (typically ?20 Gy at 21 °C) to significantly reduce the electron lifetime by ?50%, and then the recovery of the lifetime was monitored as a function of time at three different temperatures, 10 °C, 21 °C, and 35 °C. The lifetime recovery kinetics was exponential with a relaxation time ?{sub r} that is thermally activated with an activation energy of 1.66 eV. ?{sub r} is a few hours at 21 °C and only a few minutes at 35 °C. In experiments examining the irradiation induced effects, the a-Se film was repeatedly exposed to x-ray radiation and the changes in the drift mobility and lifetime were monitored as a function of accumulated dose D. There was no observable change in the drift mobility. At 21 °C, the concentration of x-ray induced deep traps (or capture centers), N{sub d}, increases linearly with D (N{sub d} ? D) whereas at 35 °C, the recovery process prevents a linear increase in N{sub d} with D, and N{sub d} saturates. In all cases, even under high dose irradiation (?50 Gy), the lifetime was recoverable to its original equilibrium (pre-exposure) value within a few relaxation times.

Walornyj, M.; Kasap, S. O. [Department of Electrical and Computer Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, Saskatchewan S7N 5A9 (Canada)] [Department of Electrical and Computer Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, Saskatchewan S7N 5A9 (Canada)

2013-12-07

305

Automated Chemical Analysis of Internally Mixed Aerosol Particles Using X-ray Spectromicroscopy at the Carbon K-Edge  

SciTech Connect

We have developed an automated data analysis method for atmospheric particles using scanning transmission X-ray microscopy coupled with near edge X-ray fine structure spectroscopy (STXM/NEXAFS). This method is applied to complex internally mixed submicrometer particles containing organic and inorganic material. Several algorithms were developed to exploit NEXAFS spectral features in the energy range from 278 to 320 eV for quantitative mapping of the spatial distribution of elemental carbon, organic carbon, potassium, and noncarbonaceous elements in particles of mixed composition. This energy range encompasses the carbon K-edge and potassium L2 and L3 edges. STXM/NEXAFS maps of different chemical components were complemented with a subsequent analysis using elemental maps obtained by scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM/EDX). We demonstrate the application of the automated mapping algorithms for data analysis and the statistical classification of particles.

Gilles, Mary K; Moffet, R.C.; Henn, T.; Laskin, A.

2011-01-20

306

Making use of x-ray optical effects in photoelectron-, Auger electron-, and x-ray emission spectroscopies: Total reflection, standing-wave excitation, and resonant effects  

SciTech Connect

We present a general theoretical methodology and related open-access computer program for carrying out the calculation of photoelectron, Auger electron, and x-ray emission intensities in the presence of several x-ray optical effects, including total reflection at grazing incidence, excitation with standing-waves produced by reflection from synthetic multilayers and at core-level resonance conditions, and the use of variable polarization to produce magnetic circular dichroism. Calculations illustrating all of these effects are presented, including in some cases comparisons to experimental results. Sample types include both semi-infinite flat surfaces and arbitrary multilayer configurations, with interdiffusion/roughness at their interfaces. These x-ray optical effects can significantly alter observed photoelectron, Auger, and x-ray intensities, and in fact lead to several generally useful techniques for enhancing surface and buried-layer sensitivity, including layer-resolved densities of states and depth profiles of element-specific magnetization. The computer program used in this study should thus be useful for a broad range of studies in which x-ray optical effects are involved or are to be exploited in next-generation surface and interface studies of nanoscale systems.

Yang, S.-H. [IBM Almaden Research Center, San Jose, California 95120 (United States); Gray, A. X. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94740 (United States); Department of Physics, University of California at Davis, Davis, California 95616 (United States); Stanford Institute for Materials and Energy Science, Stanford University and SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Kaiser, A. M. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94740 (United States); Department of Physics, University of California at Davis, Davis, California 95616 (United States); Peter Grunberg Institute, PGI-6, Forschungszentrum Juelich, 52425 Juelich (Germany); Mun, B. S. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Applied Physics, Hanyang University, Ansan, Gyeonggi 426-791 (Korea, Republic of); Sell, B. C. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94740 (United States); Department of Physics, University of California at Davis, Davis, California 95616 (United States); Department of Physics, Otterbein College, Westerville, Ohio 43081 (United States); Kortright, J. B. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94740 (United States); Fadley, C. S. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94740 (United States); Department of Physics, University of California at Davis, Davis, California 95616 (United States)

2013-02-21

307

RADIOCHEMICAL ANALYSIS BY HIGH SENSITIVITY DUAL-OPTIC MICRO X-RAY FLUORESCENCE  

EPA Science Inventory

A novel dual-optic micro X-ray fluorescence instrument will be developed to do radiochemical analysis of high-level radioactive wastes at DOE sites such as Savannah River Site and Hanford. This concept incorporates new X-ray optical elements such as monolithic polycapillaries and...

308

A Computer Program for Calculation of Calibration Curves for Quantitative X-Ray Diffraction Analysis.  

ERIC Educational Resources Information Center

Describes a FORTRAN IV program written to supplement a laboratory exercise dealing with quantitative x-ray diffraction analysis of mixtures of polycrystalline phases in an introductory course in x-ray diffraction. Gives an example of the use of the program and compares calculated and observed calibration data. (Author/GS)

Blanchard, Frank N.

1980-01-01

309

Quantitative Analysis of the Resolved X-ray Emission Line Profiles of O Stars  

E-print Network

Quantitative Analysis of the Resolved X-ray Emission Line Profiles of O Stars David Cohen.swarthmore.edu/~cohen/presentations/CfA_11jun07.pdf #12;1. Chandra spectra: emission lines are broad and asymmetric 2. Hot-star X-rays in context 3. Hot-star winds 4. Emission line shapes: constraints on hot plasma distribution and wind mass

Cohen, David

310

Accurate macromolecular structures using minimal measurements from X-ray free-electron lasers  

PubMed Central

X-ray free-electron laser (XFEL) sources enable the use of crystallography to solve three-dimensional macromolecular structures under native conditions and free from radiation damage. Results to date, however, have been limited by the challenge of deriving accurate Bragg intensities from a heterogeneous population of microcrystals, while at the same time modeling the X-ray spectrum and detector geometry. Here we present a computational approach designed to extract statistically significant high-resolution signals from fewer diffraction measurements. PMID:24633409

Hattne, Johan; Echols, Nathaniel; Tran, Rosalie; Kern, Jan; Gildea, Richard J.; Brewster, Aaron S.; Alonso-Mori, Roberto; Glöckner, Carina; Hellmich, Julia; Laksmono, Hartawan; Sierra, Raymond G.; Lassalle-Kaiser, Benedikt; Lampe, Alyssa; Han, Guangye; Gul, Sheraz; DiFiore, Dörte; Milathianaki, Despina; Fry, Alan R.; Miahnahri, Alan; White, William E.; Schafer, Donald W.; Seibert, M. Marvin; Koglin, Jason E.; Sokaras, Dimosthenis; Weng, Tsu-Chien; Sellberg, Jonas; Latimer, Matthew J.; Glatzel, Pieter; Zwart, Petrus H.; Grosse-Kunstleve, Ralf W.; Bogan, Michael J.; Messerschmidt, Marc; Williams, Garth J.; Boutet, Sébastien; Messinger, Johannes; Zouni, Athina; Yano, Junko; Bergmann, Uwe; Yachandra, Vittal K.; Adams, Paul D.; Sauter, Nicholas K.

2014-01-01

311

Prevailing features of X-ray induced molecular electron spectra revealed with fullerenes  

E-print Network

Intense X-ray photo-absorption from short and intense pulses by a molecule triggers complicated electron and subsequently ion dynamics leading to photo-electron spectra which are difficult to interpret. Illuminating fullerenes offers a way to separate out the electron dynamics. Moreover, the fullerene cage confines spatially the origin of photo and Auger electrons. Together with the sequential nature of the photo processes at intensities available at X-ray free electron lasers, this allows for a remarkably detailed interpretation of the photo-electron spectra as we will demonstrate. The general features derived can serve as a paradigm for less well-defined situations in other large molecules or clusters.

Garibay, Abraham Camacho; Rost, Jan M

2014-01-01

312

Serial femtosecond X-ray diffraction of 30S ribosomal subunit microcrystals in liquid suspension at ambient temperature using an X-ray free-electron laser  

PubMed Central

High-resolution ribosome structures determined by X-ray crystallography have provided important insights into the mechanism of translation. Such studies have thus far relied on large ribosome crystals kept at cryogenic temperatures to reduce radiation damage. Here, the application of serial femtosecond X-ray crystallography (SFX) using an X-ray free-electron laser (XFEL) to obtain diffraction data from ribosome microcrystals in liquid suspension at ambient temperature is described. 30S ribosomal subunit microcrystals diffracted to beyond 6?Å resolution, demonstrating the feasibility of using SFX for ribosome structural studies. The ability to collect diffraction data at near-physiological temperatures promises to provide fundamental insights into the structural dynamics of the ribosome and its functional complexes. PMID:23989164

Demirci, Hasan; Sierra, Raymond G.; Laksmono, Hartawan; Shoeman, Robert L.; Botha, Sabine; Barends, Thomas R. M.; Nass, Karol; Schlichting, Ilme; Doak, R. Bruce; Gati, Cornelius; Williams, Garth J.; Boutet, Sébastien; Messerschmidt, Marc; Jogl, Gerwald; Dahlberg, Albert E.; Gregory, Steven T.; Bogan, Michael J.

2013-01-01

313

Design and measurement of a Cu L-edge x-ray filter for free electron laser pumped x-ray laser experiments  

SciTech Connect

An inner-shell photoionized x-ray laser pumped by the Linac Coherent Light Source (LCLS) free electron laser has been proposed recently. The measurement of the on-axis 849 eV Ne K{alpha} laser and protection of the x-ray spectrometer from damage require attenuation of the 1 keV LCLS beam. An Al/Cu foil combination is well suited, serving as a low energy bandpass filter below the Cu L-edge at 933 eV. A high resolution grating spectrometer is used to measure the transmission of a candidate filter with an intense laser-produced x-ray backlighter developed at the Lawrence Livermore National Laboratory Jupiter Laser Facility Janus. The methodology and discussion of the observed fine structure above the Cu L-edge will be presented.

Dunn, J.; London, R. A.; Rohringer, N. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Cone, K. V. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Department of Applied Sciences, University of California, Davis, California 95616 (United States); Rocca, J. J. [NSF Center for Extreme Ultraviolet Science and Technology, Colorado State University, Fort Collins, Colorado 80523 (United States)

2010-10-15

314

Design and measurement of a Cu L-edge x-ray filter for free electron laser pumped x-ray laser experimentsa)  

NASA Astrophysics Data System (ADS)

An inner-shell photoionized x-ray laser pumped by the Linac Coherent Light Source (LCLS) free electron laser has been proposed recently. The measurement of the on-axis 849 eV Ne K? laser and protection of the x-ray spectrometer from damage require attenuation of the 1 keV LCLS beam. An Al/Cu foil combination is well suited, serving as a low energy bandpass filter below the Cu L-edge at 933 eV. A high resolution grating spectrometer is used to measure the transmission of a candidate filter with an intense laser-produced x-ray backlighter developed at the Lawrence Livermore National Laboratory Jupiter Laser Facility Janus. The methodology and discussion of the observed fine structure above the Cu L-edge will be presented.

Dunn, J.; London, R. A.; Cone, K. V.; Rocca, J. J.; Rohringer, N.

2010-10-01

315

Interaction of ethidium bromide with yeast cells investigated by electron probe X-ray microanalysis  

Microsoft Academic Search

Summary K+ efflux provoked by ethidium proceeds partially as an all-or-none effect by which the diffusion barrier for K+ is disrupted and partially from still intact cells, presumably by exchange against ethidium. This is shown by the application of an electron probe microanalysis X-ray technique by which the K+ content of a number of individual cells is analyzed.

A. P. R. Theuvenet; R. J. M. Bindels; J. M. M. van Amelsvoort; G. W. F. H. Borst-Pauwels; A. L. H. Stols

1983-01-01

316

Parametric X-ray Radiation and Diffraction Bremsstrahlung from Moderately Relativistic Electrons in Pyrolytic Graphite Crystal  

NASA Astrophysics Data System (ADS)

Spectral maxima of parametric X-ray radiation (PXR) and diffraction bremsstrahlung (DBS) from moderately relativistic electrons and bremsstrahlung interacting with crystal have been observed. The maxima position of PXR and DBS depends on the crystal orientation angle and corresponds to theoretical calculations.

Vagner, A. R.; Potylitsyn, A. P.; Kuznecov, S. I.; Uglov, S. R.; Zabaev, V. N.; Razin, S. V.

2007-11-01

317

Field Emission Scanning Electron Microscopy (FE-SEM) and Energy Dispersive X-Ray (EDX) Spectroscopy  

E-print Network

Field Emission Scanning Electron Microscopy (FE-SEM) and Energy Dispersive X-Ray (EDX) Spectroscopy Microscope (FE-SEM) as shown in Figure 1. The FE-SEM combines the versatility of PC control with a novel mm working distance. The FE-SEM also offers excellent low kV performance with resolution of 2.5 nm

Gelfond, Michael

318

Interstitials and their agglomerates in electron irradiated gold investigated by diffuse X-ray scattering  

Microsoft Academic Search

Single crystals of gold have been irradiated at a temperature of 5 K with 3 MeV electrons. The radiation induced defects were investigated by measurements of the Huang diffuse scattering of X-rays, the change of the lattice parameter and the change of the electrical resistivity. Even at the lowest irradiation dose (concentration of Frenkel defects ? 75 ppm) no single

E. Segura; P. Ehrhart

1979-01-01

319

Investigation of Interstitials in Electron-Irradiated Aluminum by Diffuse-X-Ray Scattering Experiments  

Microsoft Academic Search

The diffuse scattering of x rays (Cu Kalphal) from single crystals of aluminum has been investigated after low-temperature electron irradiation (defect concentrations 3 × 10-4 and 5 × 10-4). The measurements were made near the (200), (400), (220), and (222) Bragg reflections in directions both parallel and perpendicular to the scattering vector. These measurements were repeated after a number of

P. Ehrhart; W. Schilling

1973-01-01

320

SCANNING ELECTRON MICROSCOPY/X-RAY FLUORESCENCE CHARACTERIZATION OF POST-ABATEMENT DUST  

EPA Science Inventory

Scanning electron microscopy (SEM) and laboratory X-ray fluorescence (XRF) were used to characterize post-abatement dust collected with a HEPA filtered vacuum. hree size fractions of resuspended dust (0-30 pm, 2.5-15 pm, and ...

321

Demonstration of self-seeding in a hard-X-ray free-electron laser  

NASA Astrophysics Data System (ADS)

The Linac Coherent Light Source (LCLS) is an X-ray free-electron laser at the SLAC National Accelerator Laboratory, which has been operating since 2009 for a wide range of scientific research. The free-electron laser process at LCLS is based on self-amplified spontaneous emission (SASE) where spontaneous emission from the initial electron beam shot noise is amplified by its interaction with the electrons over a long magnetic undulator. Although SASE is very effective, producing tremendously powerful, ultrashort X-ray beams, the start-up from noise leaves poor temporal coherence and a broad, noisy spectrum. We present experimental results of a new method, suggested by colleagues at DESY, allowing self-seeding using X-rays from the first half of the undulator to seed the second half through a diamond-based monochromator, producing near Fourier-transform-limited X-ray pulses with 0.4-0.5 eV bandwidth at 8-9 keV. These results demonstrate self-seeding at ångstrom wavelengths with a relative bandwidth reduction of 40-50 with respect to SASE.

Amann, J.; Berg, W.; Blank, V.; Decker, F.-J.; Ding, Y.; Emma, P.; Feng, Y.; Frisch, J.; Fritz, D.; Hastings, J.; Huang, Z.; Krzywinski, J.; Lindberg, R.; Loos, H.; Lutman, A.; Nuhn, H.-D.; Ratner, D.; Rzepiela, J.; Shu, D.; Shvyd'Ko, Yu.; Spampinati, S.; Stoupin, S.; Terentyev, S.; Trakhtenberg, E.; Walz, D.; Welch, J.; Wu, J.; Zholents, A.; Zhu, D.

2012-10-01

322

Spectrometer for hard X-ray free-electron laser based on diffraction focusing.  

PubMed

X-ray free-electron lasers (XFELs) generate sequences of ultra-short spatially coherent pulses of X-ray radiation. A diffraction focusing spectrometer (DFS), which is able to measure the whole energy spectrum of the radiation of a single XFEL pulse with an energy resolution of ?E/E 2 × 10(-6), is proposed. This is much better than for most modern X-ray spectrometers. Such resolution allows one to resolve the fine spectral structure of the XFEL pulse. The effect of diffraction focusing occurs in a single-crystal plate due to dynamical scattering, and is similar to focusing in a Pendry lens made from a metamaterial with a negative refraction index. Such a spectrometer is easier to operate than those based on bent crystals. It is shown that the DFS can be used in a wide energy range from 5 keV to 20 keV. PMID:23412482

Kohn, V G; Gorobtsov, O Y; Vartanyants, I A

2013-03-01

323

A waveguide electron cyclotron resonance source of X-ray emission for low-dose introscopy  

NASA Astrophysics Data System (ADS)

It is shown that a "point" target in a conventional evacuated waveguide in the magnetic field of a mirror trap formed by two disk magnets axially magnetized in the direction perpendicular to the electric field vector represents a source of X-ray bremsstrahlung of electrons accelerated in an ECR discharge with a broad range of photon energies up to 0.8 MeV. The dosage rate of the source is ˜1 R/h. The source fed from a conventional microwave oven has small dimensions and a low weight. It is easy-to-use and is suitable as a laboratory tool, in particular, in radiobiology and introscopy. After passing through the object, X-ray emission is recorded by a digital camera with the help of a highly sensitive X-ray fluorescent screen, which converts it into an optical image.

Sergeichev, K. F.; Ionidi, V. Yu.; Karfidov, D. M.; Lukina, N. A.

2013-12-01

324

Electron-positron pairs, Compton reflection, and the X-ray spectra of active galactic nuclei  

NASA Technical Reports Server (NTRS)

It is shown here that reprocessing of radiation fron nonthermal pair cascades by cold material in the central parts of active galactic nuclei (AGN) gives rise to X-ray and gamma-ray spectra that satisfy current observational constraints. An average 1-30 keV X-ray spectral index alpha(x) of about 0.7 in the compact range 30-300 is obtained for a wide range of Lorentz factors of the injected electrons. The gamma-ray spectra are steep, with alpha(gamma) about two, and satisfy the observational constraints. Radiation from pair cascades exhibits steep power law decreases in soft X-rays similar to those observed in AGN. The overall picture is consistent with AGN having an accretion disk which intercepts and reprocesses a substantial fraction of the nonthermal continuum incident upon it from above and below.

Zdziarski, Andrzej A.; Ghisellini, Gabriele; George, Ian M.; Fabian, A. C.; Svensson, Roland; Done, Chris

1990-01-01

325

Emerging opportunities in structural biology with X-ray free-electron lasers  

PubMed Central

X-ray free-electron lasers (X-FELs) produce X-ray pulses with extremely brilliant peak intensity and ultrashort pulse duration. It has been proposed that radiation damage can be “outrun” by using an ultra intense and short X-FEL pulse that passes a biological sample before the onset of significant radiation damage. The concept of “diffraction-before-destruction” has been demonstrated recently at the Linac Coherent Light Source, the first operational hard X-ray FEL, for protein nanocrystals and giant virus particles. The continuous diffraction patterns from single particles allow solving the classical “phase problem” by the oversampling method with iterative algorithms. If enough data are collected from many identical copies of a (biological) particle, its three-dimensional structure can be reconstructed. We review the current status and future prospects of serial femtosecond crystallography (SFX) and single-particle coherent diffraction imaging (CDI) with X-FELs. PMID:22922042

Schlichting, Ilme; Miao, Jianwei

2012-01-01

326

Investigations of large x-ray optics for free electron lasers  

NASA Astrophysics Data System (ADS)

A free electron laser (FEL) is being set up at DESY (Deutsches Elektronen Synchrotron, Hamburg, Germany). In the current XUV range of the FEL, total-reflection X-ray mirrors are needed for beam guidance, beam alignment, and monochromatisation. Such X-ray optics are used at a grazing incidence angle of about 2° thus a maximum length of about 500 mm is required. Due to the working range of the FEL (50 - 200 eV), carbon has been selected as a suitable material with an absorption edge at 284 eV. The amorphous carbon coatings were manufactured by magnetron sputtering in a special UHV system for large deposition at GKSS research centre (Geesthacht, Germany). The variation in film thickness over the whole length has been investigated by X-ray reflectometry (XRR). Good uniformity (better than 2 %) and low roughness (< 0.5 nm) have been observed.

Stormer, Michael; Liard-Cloup, Audrey; Felten, Frank; Jacobi, Sandra; Steeg, Barbara; Feldhaus, Josef; Bormann, Rudiger

2004-10-01

327

Infrared catastrophe and tunneling into strongly correlated electron systems: Beyond the x-ray edge limit  

Microsoft Academic Search

We develop a nonperturbative method to calculate the electron propagator in\\u000alow-dimensional and strongly correlated electron systems. The method builds on\\u000aour earlier work using a Hubbard-Stratonovich transformation to map the\\u000atunneling problem to the x-ray edge problem, which accounts for the infrared\\u000acatastrophe caused by the sudden introduction of a new electron into a\\u000aconductor during a tunneling event.

Kelly R. Patton; Michael R. Geller

2006-01-01

328

Infrared catastrophe and tunneling into strongly correlated electron systems: Beyond the x-ray edge limit  

Microsoft Academic Search

We develop a nonperturbative method to calculate the electron propagator in low-dimensional and strongly correlated electron systems. The method builds on our earlier work using a Hubbard-Stratonovich transformation to map the tunneling problem to the x-ray edge problem, which accounts for the infrared catastrophe caused by the sudden introduction of a new electron into a conductor during a tunneling event.

Kelly R. Patton; Michael R. Geller

2006-01-01

329

X-ray micro-analysis of aluminium in pumpkinseed gills.  

PubMed

Energy dispersive X-ray micro-analysis was applied to study the (sub-) cellular distribution of aluminium at the gill level of "acid-resistant pumpkinseeds (Lepomis gibbosus) exposed to acidified water (pH = 4.2) and an elevated level of aluminium (1.4 mg Al/l, exposure period = 21 days). Electron dense deposits, located in invaginations as well as inside the gill tissue, were shown to contain elevated levels of aluminium and phosphorus. The micro-analytical findings suggest that the pumpkinseed possesses a defence mechanism, in which the intracellular accumulation of aluminium is limited to restricted sites and to storage in macrophages. PMID:8398556

Eeckhaoudt, S; Jacob, W; Witters, H; Van Grieken, R

1993-01-01

330

Investigation of electron trajectories of an x-ray tube in magnetic fields of MR scanners.  

PubMed

A hybrid x-ray/MR system combining an x-ray fluoroscopic system and an open-bore magnetic resonance (MR) system offers advantages from both powerful imaging modalities and thus can benefit numerous image-guided interventional procedures. In our hybrid system configurations, the x-ray tube and detector are placed in the MR magnet and therefore experience a strong magnetic field. The electron beam inside the x-ray tube can be deflected by a misaligned magnetic field, which may damage the tube. Understanding the deflection process is crucial to predicting the electron beam deflection and avoiding potential damage to the x-ray tube. For this purpose, the motion of an electron in combined electric (E) and magnetic (B) fields was analyzed theoretically to provide general solutions that can be applied to different geometries. For two specific cases, a slightly misaligned strong field and a perpendicular weak field, computer simulations were performed with a finite-element method program. In addition, experiments were conducted using an open MRI magnet and an inserted electromagnet to quantitatively verify the relationship between the deflections and the field misalignment. In a strong (B > E/c; c: speed of light) and slightly misaligned magnetic field, the deflection in the plane of E and B caused by electrons following the magnetic field lines is the dominant component compared to the deflection in the E X B direction due to the drift of electrons. In a weak magnetic field (B < or = E/c), the main deflection is in the E x B direction and is caused by the perpendicular component of the magnetic field. PMID:17654908

Wen, Zhifei; Fahrig, Rebecca; Conolly, Steven; Pelc, Norbert J

2007-06-01

331

Investigation of electron trajectories of an x-ray tube in magnetic fields of MR scanners  

SciTech Connect

A hybrid x-ray/MR system combining an x-ray fluoroscopic system and an open-bore magnetic resonance (MR) system offers advantages from both powerful imaging modalities and thus can benefit numerous image-guided interventional procedures. In our hybrid system configurations, the x-ray tube and detector are placed in the MR magnet and therefore experience a strong magnetic field. The electron beam inside the x-ray tube can be deflected by a misaligned magnetic field, which may damage the tube. Understanding the deflection process is crucial to predicting the electron beam deflection and avoiding potential damage to the x-ray tube. For this purpose, the motion of an electron in combined electric (E) and magnetic (B) fields was analyzed theoretically to provide general solutions that can be applied to different geometries. For two specific cases, a slightly misaligned strong field and a perpendicular weak field, computer simulations were performed with a finite-element method program. In addition, experiments were conducted using an open MRI magnet and an inserted electromagnet to quantitatively verify the relationship between the deflections and the field misalignment. In a strong (B>>E/c; c: speed of light) and slightly misaligned magnetic field, the deflection in the plane of E and B caused by electrons following the magnetic field lines is the dominant component compared to the deflection in the ExB direction due to the drift of electrons. In a weak magnetic field (B{<=}E/c), the main deflection is in the ExB direction and is caused by the perpendicular component of the magnetic field.

Wen Zhifei; Fahrig, Rebecca; Conolly, Steven; Pelc, Norbert J. [Departments of Radiology and Physics, Stanford University, Stanford, California 94305 (United States); Departments of Radiology, Stanford University, Stanford, California 94305 (United States); Department of Bioengineering, University of California, Berkeley, California 94720 (United States); Departments of Radiology and Bioengineering, Stanford University, Stanford, California 94305 (United States)

2007-06-15

332

X-ray spectroscopic study of the electronic structure of CuCrO2  

NASA Astrophysics Data System (ADS)

The electronic structure of the p -type transparent conducting oxide CuCrO2 has been studied by x-ray photoemission, x-ray absorption, and x-ray emission spectroscopies. The upper part of the valence band derives mainly from Cu3d and Cr3d states while the lower valence-band states are of dominant O2p atomic character, but with pronounced mutual hybridization among Cu3d , Cr3d , and O2p states. Site specific electronic excitations have been studied by resonant inelastic x-ray scattering at the CuL and CrL edges. Inelastic loss at the CuL edge is dominated by on-site interband excitations similar to those found in Cu2O , while at the CrL edge localized excitations arising from ligand field splitting of the Cr3d levels are observed. Mg doping on the Cr sites in CuCrO2 is shown to lead to a pronounced shift in the Fermi level toward the edge of the valence band. The experimental data are compared to electronic structure calculations on CuCrO2 carried out using density-functional methods corrected for onsite Coulomb repulsion.

Arnold, T.; Payne, D. J.; Bourlange, A.; Hu, J. P.; Egdell, R. G.; Piper, L. F. J.; Colakerol, L.; de Masi, A.; Glans, P.-A.; Learmonth, T.; Smith, K. E.; Guo, J.; Scanlon, D. O.; Walsh, A.; Morgan, B. J.; Watson, G. W.

2009-02-01

333

X-ray Spectroscopic Study of the Electronic Structure of CuCrO2  

SciTech Connect

The electronic structure of the p-type transparent conducting oxide CuCrO{sub 2} has been studied by x-ray photoemission, x-ray absorption, and x-ray emission spectroscopies. The upper part of the valence band derives mainly from Cu?3d and Cr?3d states while the lower valence-band states are of dominant O?2p atomic character, but with pronounced mutual hybridization among Cu?3d, Cr?3d, and O?2p states. Site specific electronic excitations have been studied by resonant inelastic x-ray scattering at the Cu?L and Cr?L edges. Inelastic loss at the Cu?L edge is dominated by on-site interband excitations similar to those found in Cu{sub 2}O, while at the Cr?L edge localized excitations arising from ligand field splitting of the Cr?3d levels are observed. Mg doping on the Cr sites in CuCrO{sub 2} is shown to lead to a pronounced shift in the Fermi level toward the edge of the valence band. The experimental data are compared to electronic structure calculations on CuCrO{sub 2} carried out using density-functional methods corrected for onsite Coulomb repulsion.

Arnold, T.; Payne, D; Bourlange, A; Hu, J; Egdell, R; Piper, L; Colakerol, L; DeMasi, A; Glans, P; et. al.

2009-01-01

334

Bremsstrahlung x ray images of isolated electron patches at high latitudes  

SciTech Connect

Small isolated patches of energetic electron precipitation have been observed at high latitudes with a bremsstrahlung X ray imager in the Stimulated Emission of Energetic Particles (SEEP) payload on the polar-orbiting S81-1 satellite. Twenty-nine patches of X rays (>4 keV) with typical widths of approx.200 km were observed in June 1982 at invariant latitudes between 65/sup 0/ and 83/sup 0/ with a median latitude of 72.5/sup 0/ The majority of X ray patches occurred from dusk until dawn, but a few were present in the early afternoon hours. The observed energy spectra were relatively soft (e fold energies about 1--6 keV) and independent of invariant latitude, magnetic local time, or geomagnetic activity. The occurrence frequency of the patches was somewhat greater at times of high geomagnetic activity. The patches were usually oblong by factors up to 3.7, with a median value of 1.75. No strongly preferred alignment was found. Comparisons of the direct electron measurements and the X ray observations from the same satellite have shown that in some cases the small isolated patches of electron precipitation at high latitudes may undergo significant changes in position on time scales of the order of a few seconds.

Imhof, W.L.; Voss, H.D.; Datlowe, D.W.; Mobilia, J.

1985-07-01

335

Observation and X-ray analysis of the microstructures for a bonding material of C\\/C composite and copper  

Microsoft Academic Search

The purpose of this study is to examine the microstructure of a bonding material of C\\/C composite and copper before and after thermal shock tests. Optical and scanning electron microscopy, and energy dispersive X-ray analysis were used to study the microstructures before and after thermal shock tests. In this study, the specimen were given thermal shock without an active cooling,

A. Kurumada; B. McEnaney; T. Oku; K. Kawamata; O. Motojima; N. Noda

1996-01-01

336

Extension of x-ray imaging linear systems analysis to detectors with energy discrimination capability  

SciTech Connect

A figure of merit, the broad-spectrum generalized detective quantum efficiency, which describes the performance of digital detectors designed for broad-spectrum x-ray imaging is derived from linear response theory. This measure of the imaging efficacy of an x-ray sensor is obtained when detector contrast modulation in the domain of x-ray energy is introduced in the Fourier-based analysis of digital systems. A method is proposed to scale existing figures of merit according to the energy-dependent response of the detector and the spectral shape of the x-ray beam. The new figure of merit obtained with this method provides an extended description of system performance when comparing energy-integrating, single-photon counting, and future energy-sensitive x-ray imaging sensors. The applicability of this linear system analysis is restricted to the tasks of low-contrast object detection in radiography. The method for scaling the figure of merit to take into consideration broad-spectrum conditions is applied to mammography for future energy-dependent detectors. An approximation valid in the typical mammographic x-ray energy range is used to calculate the broad-spectrum generalized detective quantum efficiency at zero spatial frequency, for several mammographic x-ray spectra. X-ray energy weighting in mammography is investigated in the context of simulated tumors and microcalcifications detection by comparing this figure of merit, calculated for different detector technologies, under ideal imaging conditions, at zero spatial frequency.

Marchal, Julien P. [MRC/UCT Medical Imaging Research Unit, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Observatory 7925, Cape Town (South Africa)

2005-08-15

337

Mode shape analysis techniques using synchrotron X-ray topography  

Microsoft Academic Search

X-ray topography using synchrotron radiation is used to investigate vibrational states in quartz resonators. After a brief review of different methods and possibilities obtained with synchrotron radiation, some observations on vibration modes, especially on coupled piezo-electric components in quartz AT and BT resonators, are reported. The results from experiments reveal time-progressive components and several complex coupled components in AT and

B. Capelle; J. Detaint; A. Zarka; Y. Zheng; J. Schwartzel

1990-01-01

338

X-ray topography analysis of bulk acoustic wave resonators  

Microsoft Academic Search

X-ray topography is first used to totally examine the fundamental modes of acoustic oscillations in the bulk-acoustic-wave\\u000a (BAW) resonator on the base of an AT-cut quartz crystal at the first and third harmonics. As is evident from the experiments,\\u000a the anharmonic longitudinal oscillations of the resonator can be visualized, just as the fundamental transverse acoustic oscillations\\u000a can be. The amplitude-frequency

D. V. Irzhak; D. V. Roshchupkin; D. V. Punegov; S. A. Sakharov

2007-01-01

339

ANALYSIS AND MITIGATION OF X-RAY HAZARD GENERATED FROM HIGH INTENSITY LASER-TARGET INTERACTIONS  

SciTech Connect

Interaction of a high intensity laser with matter may generate an ionizing radiation hazard. Very limited studies have been made, however, on the laser-induced radiation protection issue. This work reviews available literature on the physics and characteristics of laser-induced X-ray hazards. Important aspects include the laser-to-electron energy conversion efficiency, electron angular distribution, electron energy spectrum and effective temperature, and bremsstrahlung production of X-rays in the target. The possible X-ray dose rates for several femtosecond Ti:sapphire laser systems used at SLAC, including the short pulse laser system for the Matter in Extreme Conditions Instrument (peak power 4 TW and peak intensity 2.4 x 10{sup 18} W/cm{sup 2}) were analysed. A graded approach to mitigate the laser-induced X-ray hazard with a combination of engineered and administrative controls is also proposed.

Qiu, R.; Liu, J.C.; Prinz, A.A.; Rokni, S.H.; Woods, M.; Xia, Z.; /SLAC; ,

2011-03-21

340

Electronic emission of radio-sensitizing gold nanoparticles under X-ray irradiation : experiment and simulations  

E-print Network

In this paper we present new results on electronic emission of Gold Nanoparticles (GNPs) using X-ray photoelectron spectroscopy (XPS) and compare them to the gold bulk electron emission. This subject has undergone new interest within the perspective of using GNPs as a radiotherapy enhancer. The experimental results were simulated using various models (Livermore and PENELOPE) of the Geant 4 simulation toolkit dedicated to the calculation of the transportation of particles through the matter. Our results show that the GNPs coating is a key parameter to correctly construe the experimental GNPs electronic emission after X-ray irradiation and point out some limitations of the PENELOPE model. Using XPS spectra and Geant4 Livermore simulations,we propose a method to determine precisely the coating surface density of the GNPs. We also show that the expected intrinsic nano-scale electronic emission enhancement effect - suspected to contribute to the GNPs radio-sensitizing properties - participates at most for a few pe...

Casta, R; Sence, M; Moretto-Capelle, P; Cafarelli, P; Amsellem, A; Sicard-Roselli, C

2014-01-01

341

Laser Assisted Emittance Exchange: Downsizing the X-ray Free Electron Laser  

SciTech Connect

A technique is proposed to generate electron beam with ultralow transverse emittance through laser assisted transverse-to-longitudinal emittance exchange. In the scheme a laser operating in the TEM10 mode is used to interact with the electron beam in a dispersive region and to initiate the emittance exchange. It is shown that with the proposed technique one can significantly downsize an x-ray free electron laser (FEL), which may greatly extend the availability of these light sources. A hard x-ray FEL operating at 1.5 {angstrom} with a saturation length within 30 meters using a 3.8 GeV electron beam is shown to be practically feasible.

Xiang, Dao; /SLAC

2009-12-11

342

Duplex multiwire proportional x-ray detector for multichord time-resolved soft x-ray and electron temperature measurements on T-10 tokamak  

SciTech Connect

Compact 64-channel multiwire proportional chamber is successfully used on T-10 and TCV tokamaks as a continuous-current soft x-ray detectors. The duplex multiwire proportional x-ray detector is a new generation of these detectors. It has been designed for simultaneous multichord measurement of plasma soft x-ray emissivity in a two spectral ranges and determination of the electron temperature by the two-absorber method. The detector consists of two identical multiwire proportional chambers filled by 90%Kr+10%CH{sub 4} gas mixture at atmospheric pressure. The first multiwire chamber has 64 channels. The second multiwire chamber (installed behind the first one) has 32 channels. Both chambers view the plasma through the one helium-filled slot-hole camera. Thus, the first multiwire chamber serves as an absorber filter for the second one. Such construction of the detector allows us in addition to soft x-ray measurements to provide measurement of the plasma core electron temperature with spatial resolution of about 2 cm and a time resolution of less than 50 {mu}s. The construction of the detector and experimental results illustrating the potential of the diagnostic are presented.

Sushkov, A. V.; Andreev, V. F.; Kravtsov, D. E. [Russian Research Centre Kurchatov Institute, 123182 Moscow (Russian Federation)

2008-10-15

343

Duplex multiwire proportional x-ray detector for multichord time-resolved soft x-ray and electron temperature measurements on T-10 tokamak.  

PubMed

Compact 64-channel multiwire proportional chamber is successfully used on T-10 and TCV tokamaks as a continuous-current soft x-ray detectors. The duplex multiwire proportional x-ray detector is a new generation of these detectors. It has been designed for simultaneous multichord measurement of plasma soft x-ray emissivity in a two spectral ranges and determination of the electron temperature by the two-absorber method. The detector consists of two identical multiwire proportional chambers filled by 90%Kr+10%CH(4) gas mixture at atmospheric pressure. The first multiwire chamber has 64 channels. The second multiwire chamber (installed behind the first one) has 32 channels. Both chambers view the plasma through the one helium-filled slot-hole camera. Thus, the first multiwire chamber serves as an absorber filter for the second one. Such construction of the detector allows us in addition to soft x-ray measurements to provide measurement of the plasma core electron temperature with spatial resolution of about 2 cm and a time resolution of less than 50 mus. The construction of the detector and experimental results illustrating the potential of the diagnostic are presented. PMID:19044481

Sushkov, A V; Andreev, V F; Kravtsov, D E

2008-10-01

344

IDENTIFICATION OF SELECTED SILICATE MINERALS AND THEIR ASBESTIFORM VARIETIES BY ELECTRON OPTICAL AND X-RAY TECHNIQUES  

EPA Science Inventory

Illustrations of electron micrographs showing morphology, electron diffraction patterns, energy dispersive X-ray spectra, and X-ray diffraction patterns of selected silicates and their asbestiform varieties are presented as an aid in their identification. A method for preparing r...

345

Femtosecond X-ray Laser induced transient electronic phase change observed in fullerene C60  

E-print Network

X-ray Free-Electron Lasers (XFELs) deliver X-ray pulses with a coherent flux that is approximately eight orders of magnitude greater than that available from a modern third generation synchrotron source. The power density in an XFEL pulse may be so high that it can modify the electronic properties of a sample on a femtosecond timescale. Exploration of the interaction of intense coherent X-ray pulses and matter is of both intrinsic scientific interest, and of critical importance to the interpretation of experiments that probe the structures of materials using high-brightness femtosecond XFEL pulses. In this letter, we report observations of the diffraction of an extremely intense 32 fs nanofocused X-ray pulses by a powder sample of crystalline C60. We find that the diffraction pattern at the highest available incident power exhibits significant structural signatures that are absent in data obtained at both third-generation synchrotron sources or from XFEL sources operating at low output power. These signatures...

Abbey, Brian; Darmanin, Connie; Ryan, Rebecca A; Putkunz, Corey T; Martin, Andrew V; Streltsov, Victor; Jones, Michael W M; Gaffney, Naylyn; Hofmann, Felix; Williams, Garth J; Boutet, Sebastian; Messerschmidt, Marc; Siebert, M Marvin; Williams, Sophie; Curwood, Evan; Balaur, Eugeniu; Peele, Andrew G; Nugent, Keith A; Quiney, Harry M

2012-01-01

346

Large format imaging detectors for x-ray free-electron-lasers  

NASA Astrophysics Data System (ADS)

New generation synchrotron light sources, the X-ray free electron lasers, require a two dimensional focal plane instrumentation to perform X-ray imaging from below 100eV up to 25keV. The instruments have to face the accelerator bunch structure and energy bandwidth which is different for existing (FLASH, Hamburg and LCLS, Menlo Park) and future photon sources (SACLA, Harima and XFEL, Hamburg). Within the frame of the Center for Free Electron Laser Science (CFEL), a joint effort of the Max-Planck Society, DESY and the University of Hamburg, the MPI semiconductor laboratory developed, produced and operated large area X-ray CCD detectors with a format of nearly 60cm2 image area. They show outstanding characteristics: a high readout speed due to a complete parallel signal processing, high and homogeneous quantum efficiency, low signal noise, radiation hardness and a high pixel charge handling capacitance. We will present measurement results which demonstrate the X-ray spectroscopic and imaging capabilities of the fabricated devices. We will also report on the concept and the anticipated properties of the full, large scale system. The implementation of the detector into an experimental chamber to perform measurements e.g. of macromolecules in order to determine their structure at atomic resolutions will be shown.

Hartmann, Robert; Epp, Sascha; Gorke, Hubert; Hartmann, Andreas; Hauser, Günther; Herrmann, Sven; Holl, Peter; Kimmel, Nils; Meidinger, Norbert; Reich, Christian; Rolles, Daniel; Soltau, Heike; Strüder, Lothar; Ullrich, Joachim; Weidenspointner, Georg

2011-06-01

347

Electronic states, bonding, and x-ray absorption spectra of Pd2Si  

Microsoft Academic Search

The electronic properties of Pd2 Si are analyzed in light of a self-consistent calculation of the electronic states. By using the linear muffin-tin orbitals method in the atomic-sphere approximation, energy bands, densities of states, x-ray photoabsorption spectra, and the total energy have been determined. The basic bonding interaction between Pd and Si is found to be a bonding-antibonding coupling between

O. Bisi; O. Jepsen; O. K. Andersen

1987-01-01

348

Surface characterization of oxidized myofibrils using X-ray photoelectron spectroscopy and scanning electron microscopy.  

PubMed

The functional properties of myofibrils depend largely on their surface characteristics. Changes in surface characteristics of myofibrils after chemical oxidation were elucidated using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy. Myofibrils were oxidized by a hydroxyl radical generating system. Lipid oxidation and phospholipid distribution were altered during the oxidative processing. Results from particle size analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and salt solubility indicated that protein cross-linking and fragmentation occurred during the oxidation of myofibrils. XPS analysis of C 1s, N 1s, and O 1s spectra suggested that surface chemical function concentrations changed significantly because of the modification of amino acid side chains that rendered protein cross-links and fragmentation and phospholipid alteration. Analysis of the correlation between the surface chemical composition and parameters of particle size distributions confirmed that protein carbonylation and phospholipid alteration were involved in protein surface modification. Results of the microstructure analysis were in agreement with those of particle size and XPS analysis. PMID:25005710

Sun, Weizheng; Li, Qingyun; Zhou, Feibai; Zhao, Haifeng; Zhao, Mouming

2014-07-30

349

Morphological study of energetic electron precipitation events using the satellite bremsstrahlung X ray technique  

SciTech Connect

The precipitation of energetic electrons into the atmosphere is investigated with simultaneous measurements of bremsstrahlung X rays emitted from different local time sectors performed from the low-altitude polar-orbiting satellite P78-1 with an array of X ray spectrometers (21--139 keV), each looking in a different direction. From the measurements spanning a broad interval in L, simultaneous profiles in local time are obtained of the intensities and energy spectra of the bremsstrahlung X rays which relate to the corresponding parameters for the precipitating electrons. From approx.0930 to approx.1400 MLT the average X ray intensity was found to decrease with increasing magnetic local time, whereas from approx.2200 to approx.0200 MLT, no clear trend with local time was evident. Within both of these local time intervals the average flux increased with increasing level of geomagnetic activity, and the data acquired near midnight were best organized by the AE index. The correlation between the fluxes of X rays emitted simultaneously at different magnetic local times decreased with increasing separation in local time, but a significant correlation still existed over separations as great as 3 hours. The energy spectrum was harder before midnight than after and harder before midnight than near noon. When a hard energy spectrum was observed in one local time sector, the spectra at other local times within 3 hours were significantly harder than average. From the entire set of data no evidence has been found for a distinct group of relativistic electron precipitation events.

Imhof, W.L.; Kilner, J.R.; Reagan, J.B.

1985-02-01

350

Extended x-ray-absorption fine structure-Auger process for surface structure analysis: Theoretical considerations of a proposed experiment.  

PubMed

A method for surface structure analysis is proposed. The proposed process combines x-ray photoabsorption and Auger electron emission. The extended x-ray-absorption fine structure, occurring for photon energies above an atomic absorption edge, contains structural information of the microscopic environment due to the coupling of the photoelectron final state with the atomic initial state. Measurement of the variations in the intensity of particular Auger lines, as a function of the incident radiation energy, provides a surface sensitive measure of the photoabsorption cross section in the media. Theoretical considerations of the physical processes underlying the proposed experiment and its feasibility, and a discussion of background contributions are presented. PMID:16592339

Landman, U; Adams, D L

1976-08-01

351

Confinement of hot, hard X-ray producing electrons in solar flares  

NASA Technical Reports Server (NTRS)

Possible thermal models for solar, hard X-ray emission, consisting of small volumes in which the electrons are rapidly heated to 400 million K, are examined to determine under what conditions such models can be more efficient than nonthermal models. The analysis is restricted to one dimension by supposing that the hot electrons are confined in a flux tube and that conduction and convection act only along the magnetic field. A conduction front, thin in relation to other length scales involved, separates the hot electrons from the relatively cold plasma. The range of conduction-front velocity is studied by systematizing the present knowledge of heat conduction and applying it first to a simple model in which convection is neglected, and then to a detailed numerical model in which convection is included. Convection in which mass motion goes to zero at the conduction front does not lead to a change in the conduction-front velocity compared to conduction alone, but does constitute another nonradiative energy loss which reduces the source efficiency.

Smith, D. F.; Lilliequist, C. G.

1979-01-01

352

X-ray diagnostics for investigating electron distribution functions in the central cell of the GAMMA 10 tandem mirror  

SciTech Connect

The quantum efficiency of an ultralow-energy-sensitive pure-Ge (ULE Ge) detector is investigated using synchrotron radiation from the storage ring at AIST especially for x-ray pulse-height analyses (PHAs), down to a few hundred eV. Several types of x-ray diagnostics such as x-ray PHA, x-ray absorption methods, and x-ray tomography using the ULE Ge detector, a NaI(Tl) detector, as well as a microchannel-plate tomography system are employed for investigating electron distribution functions and electron temperature profiles with preliminary central electron-cyclotron heating in the central cell of the GAMMA 10 tandem mirror. These measurements play an important role in studying an essential physics scaling of the electron temperature as a function of electron confining potential in tandem mirror plasmas.

Kohagura, J.; Cho, T.; Hirata, M.; Numakura, T.; Fukai, T.; Tomii, Y.; Kiminami, S.; Morimoto, N.; Ikuno, T.; Namiki, S.; Shimizu, K.; Ito, M.; Miyata, Y.; Minami, R.; Miyoshi, S.; Ogura, K.; Saito, N.; Saito, T.; Kariya, T. [Plasma Research Centre, University of Tsukuba, Ibaraki 305-8577 (Japan); Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan); National Institute of Advanced Industrial Science and Technology, Ibaraki 305-8568 (Japan); Toshiba Electron Tubes and Devices, Tochigi 324-8550 (Japan)

2006-10-15

353

Characteristics of X-ray radiation by a nonequilibrium energetic electron flow emerged from a formed ferrite filament  

Microsoft Academic Search

This article reports the observation of intense X-ray emission by a nonequilibrium energetic electron flow that can be produced when an explosive-formed ferrite filament is used as a plasma initiator in a high vacuum of 10 exp -5 - 10 exp -3 torr. Exposure dose measurements and pinhole photographs for the X-ray emission have shown that X-rays originate linearly along

K. Watanabe; K. Furusho; S. Kashiwabara; R. Fujimoto

1990-01-01

354

The position of the auroral energetic electron precipitation region obtained from PIXIE global X-ray observations  

Microsoft Academic Search

The Polar Ionospheric X-ray Imaging Experiment (PIXIE) on NASA's POLAR spacecraft has been making global observations of X-rays from the Earth's auroral regions since March, 1996. PIXIE is a remote-sensing global monitor of multi-keV electrons which have precipitated into the ionosphere from the magnetosphere. This study examines nine months (May, 1997 - January, 1998) of X-ray observations from the PIXIE

S. M. Petrinec; F. Fenrich; J. Mobilia; D. L. Chenette; M. A. Rinaldi; W. L. Imhof

1999-01-01

355

Tomographic analysis of the nonthermal x-ray bursts during disruption instability in the T-10 tokamak.  

PubMed

Non-thermal x-ray radiation (E? up to 150 keV) is measured in the T-10 tokamaks during disruption instability using two sets of CdTe detectors (10 vertical and 7 horizontal view detectors). Special narrow cupper tubes collimators with lead screening and CdTe detectors integrated with amplifiers inside metallic containers provides enhanced spatial resolution of the system (r ? 3 cm) and assures protection from the parasitic hard x-ray (E? up to 1.5 MeV) and electromagnetic loads during disruption. Spatial localization of the nonthermal x-ray emissivity is reconstructed using tomographic Cormack technique with SVD matrix inversion. Analysis indicated appearance of an intensive non-thermal x-ray bursts during initial stage of the disruptions at high density. The bursts are characterized by repetitive spikes (2-3 kHz) of the x-ray emissivity from the plasma core area. Analysis indicated that the spikes can be connected with acceleration of the non-thermal electrons in enhanced longitudinal electric fields induced during energy quench at the disruption instability. PMID:25362394

Savrukhin, P V; Ermolaeva, A I; Shestakov, E A; Khramenkov, A V

2014-10-01

356

Tomographic analysis of the nonthermal x-ray bursts during disruption instability in the T-10 tokamak  

NASA Astrophysics Data System (ADS)

Non-thermal x-ray radiation (E? up to 150 keV) is measured in the T-10 tokamaks during disruption instability using two sets of CdTe detectors (10 vertical and 7 horizontal view detectors). Special narrow cupper tubes collimators with lead screening and CdTe detectors integrated with amplifiers inside metallic containers provides enhanced spatial resolution of the system (r ˜ 3 cm) and assures protection from the parasitic hard x-ray (E? up to 1.5 MeV) and electromagnetic loads during disruption. Spatial localization of the nonthermal x-ray emissivity is reconstructed using tomographic Cormack technique with SVD matrix inversion. Analysis indicated appearance of an intensive non-thermal x-ray bursts during initial stage of the disruptions at high density. The bursts are characterized by repetitive spikes (2-3 kHz) of the x-ray emissivity from the plasma core area. Analysis indicated that the spikes can be connected with acceleration of the non-thermal electrons in enhanced longitudinal electric fields induced during energy quench at the disruption instability.

Savrukhin, P. V.; Ermolaeva, A. I.; Shestakov, E. A.; Khramenkov, A. V.

2014-10-01

357

Constraints on photon pulse duration from longitudinal electron beam diagnostics at a soft X-ray free-electron laser  

E-print Network

-ray free-electron laser C. Behrens1 , N. Gerasimova1 , Ch. Gerth1 , B. Schmidt1 , E.A. Schneidmiller1 , S, Ukraine (Dated: February 28, 2012) The successful operation of X-ray free-electron lasers (FELs), like the Linac Coherent Light Source or the Free-Electron Laser in Hamburg (FLASH), makes unprecedented research

358

Double-core-hole spectroscopy for chemical analysis with an intense X-ray femtosecond laser  

PubMed Central

Theory predicts that double-core-hole (DCH) spectroscopy can provide a new powerful means of differentiating between similar chemical systems with a sensitivity not hitherto possible. Although DCH ionization on a single site in molecules was recently measured with double- and single-photon absorption, double-core holes with single vacancies on two different sites, allowing unambiguous chemical analysis, have remained elusive. Here we report that direct observation of double-core holes with single vacancies on two different sites produced via sequential two-photon absorption, using short, intense X-ray pulses from the Linac Coherent Light Source free-electron laser and compare it with theoretical modeling. The observation of DCH states, which exhibit a unique signature, and agreement with theory proves the feasibility of the method. Our findings exploit the ultrashort pulse duration of the free-electron laser to eject two core electrons on a time scale comparable to that of Auger decay and demonstrate possible future X-ray control of physical inner-shell processes. PMID:21969540

Berrah, Nora; Fang, Li; Murphy, Brendan; Osipov, Timur; Ueda, Kiyoshi; Kukk, Edwin; Feifel, Raimund; van der Meulen, Peter; Salen, Peter; Schmidt, Henning T.; Thomas, Richard D.; Larsson, Mats; Richter, Robert; Prince, Kevin C.; Bozek, John D.; Bostedt, Christoph; Wada, Shin-ichi; Piancastelli, Maria N.; Tashiro, Motomichi; Ehara, Masahiro

2011-01-01

359

Parametric X-rays generated by electrons in multilayer mirrors mounted inside a betatron  

NASA Astrophysics Data System (ADS)

The measured characteristics of tunable, quasi-monochromatic X-rays from thin multilayer mirrors used as radiators mounted inside a 35 MeV betatron chamber are presented. Parametric X-ray radiation (PXR) was generated by 15-33 MeV electrons passing through two radiators consisted of a few hundreds of W/B4C bilayers with period of 14.86 and 18 A. Shifts of the PXR spectra were measured as the orientation of the multilayer radiators relative to the incident electron beam was changed. The PXR flux was determined by comparison with the yield of L fluorescence generated by electrons in the W layers of the multilayer.

Kaplin, V. V.; Uglov, S. R.; Sohoreva, V. V.; Bulaev, O. F.; Voronin, A. A.; Piestrup, M.; Gary, C.; Fuller, M.

2009-03-01

360

Electron beams and X ray radiation generated by laser wakefield in capillary tubes  

NASA Astrophysics Data System (ADS)

Laser wakefield is generated inside capillary tubes in order to study the conditions for self-injection of plasma electrons and their acceleration inside a large domain of parameters. Dielectric capillary tubes are employed to guide the laser pulse and collect laser energy around the central focal spot to favor laser propagation. Electrons are observed to be self-injected and accelerated to the 200 MeV range when a peak laser intensity as low as 5×1017 W/cm2 is used. X-rays emitted by betatron radiation constitute a precise diagnostic of the electron acceleration process. Furthermore, the peak brightness of X-rays is increased to 1021 ph/s/mm2/mrad2/0.1%BW when the laser pulse is focused to 5×1018 W/cm2, which is about 30 times higher than the value obtained by using a 2 mm gas jet.

Cros, B.; Ju, J.; Döpp, A.; Cassou, K.; Ferrari, H. E.; Maynard, G.; Genoud, G.; Wojda, F.; Svensson, K.; Burza, M.; Lundh, O.; Persson, A.; Wahlström, C.-G.

2012-12-01

361

Cluster of galaxies & Cosmology - X-ray analysis of fossil group RXJ1720.1+2360  

NASA Astrophysics Data System (ADS)

We present the results on the X-ray analysis of fossil group of galaxies RXJ1720.1+2360. Fossil Groups are systems associated to extended emission in X-rays with one single central elliptical galaxy surrounded by very faint companions. This unusual lack of bright galaxies in the group is presumably due to galactic cannibalism. In this study we present for the first time the imaging and spectral analysis of the XMM-Newton data of RXJ1720.1+2360. This work is part of a systematic study to determine the X-ray properties of fossil groups.

Lozada, Monica

2012-09-01

362

Contour shape analysis of hollow ion x-ray emission  

SciTech Connect

Hollow ion x-ray transitions originating from the configurations K{sup 0}L{sup N} have been studied via relativistic atomic structure and Stark broadening calculations. The broadening of the total contour is largely influenced by the oscillator strengths distribution over wavelengths rather than by Stark broadening alone. Interference effects between the upper and lower levels are shown to result in a considerable contour narrowing as well as in a shift of the total contour which could be either red or blue.

Rosmej, F. B.; Angelo, P. [Universite Pierre et Marie Curie, LULI-PAPD, UMR 7605, case 128, 4 Place Jussieu, 75252 Paris Cedex 05 (France); Ecole Polytechnique, Laboratoire pour Utilisation des Lasers Intenses, Physique Atomique dans les Plasmas Denses, 91128 Palaiseau Cedex (France); Aouad, Y. [Universite Pierre et Marie Curie, LULI-PAPD, UMR 7605, case 128, 4 Place Jussieu, 75252 Paris Cedex 05 (France)

2008-10-22

363

Analysis and interpretation of X-ray pulsars  

NASA Technical Reports Server (NTRS)

By careful measurements of the fluctuations in pulsar pulse periods on time scales of days and longer, researchers determined that these fluctuations are caused by changes in the rotation rate of the stellar crust apparently arising from matter accretion. The study of these fluctuations is a particularly promising way to determine the properties of accreting pulsars, because stellar rotation is relatively simple in comparison to much other X-ray source physics and can be investigated in detail. Rotation rates can be determined precisely.

Boynton, Paul E.; Deeter, John E.

1987-01-01

364

Hard x-ray tomographic studies of the destruction of an energetic electron ring  

SciTech Connect

A tomography system was designed and built at the Large Plasma Device to measure the spatial distribution of hard x-ray (100 KeV-3 MeV) emissivity. The x-rays were generated when a hot electron ring was significantly disrupted by a shear Alfven wave. The plasma is pulsed at 1 Hz (1 shot/s). A lead shielded scintillator detector with an acceptance angle defined by a lead pinhole is mounted on a rotary gimbal and used to detect the x-rays. The system measures one chord per plasma shot using only one detector. A data plane usually consists of several hundred chords. A novel Dot by Dot Reconstruction (DDR) method is introduced to calculate the emissivity profile from the line integrated data. In the experiments, there are often physical obstructions, which make measurements at certain angles impossible. The DDR method works well even in this situation. The method was tested with simulated data, and was found to be more effective than previously published methods for the specific geometry of this experiment. The reconstructed x-ray emissivity from experimental data by this method is shown.

Wang, Y.; Gekelman, W.; Pribyl, P. [Department of Physics and Astronomy, University of California - Los Angeles, Los Angeles, California 90095 (United States)

2013-05-15

365

Structural analysis of zinc phthalocyanine (ZnPc) thin films: X-ray diffraction study  

NASA Astrophysics Data System (ADS)

X-ray diffraction (XRD) was used to analyze the structure of thermally evaporated zinc phthalocyanine (ZnPc) organic thin films, as functions of the substrate temperature and film thickness. A metastable ? to stable ? phase transformation has been observed when the films are coated at higher substrate temperatures. The core structure of the zinc phthalocyanine macrocycle is formed by four isoindole units, which endows the molecule with a two-dimensional conjugated ? electron system. The structural analysis and high-resolution transmittance electron microscope images, along with simulation, support the formation of molecular arrays, with the electronic structure fixing the molecular spacing and producing mainly parallel arrays in small domains. These arrays produce the frontier orbital gap, which match the experimental values, and also the experimental data of periodicity, which can be reproduced theoretically.

Senthilarasu, S.; Hahn, Y. B.; Lee, Soo-Hyoung

2007-08-01

366

Auger Electrons via K? X-Ray Lines of Platinum Compounds for Nanotechnological Applications  

NASA Astrophysics Data System (ADS)

We will report study on the K? X-ray lines of platinum. Pt compounds, such as cisplatin, are common in biomedical applications. The active element Pt can emit or absorb hard X-rays. We have obtained the photoionization cross sections from the oscillator strengths of 1s-2p (K?) transitions in Pt ions. We find that these transitions appear as resonances in photoionization in the hard X-ray energy range of 64 - 71 keV (0.18 - 0.17 Å) below the K-shell ionization and with a strength orders of magnitude higher compared to that at the K-shell ionization. This is the focus of our study for possible initiation of an emission cascade of Auger electrons at the resonant energy. We will present the oscillator strengths and attenuation coefficients per unit mass for all the K? transitions in the event platinum cascades through various, namely from fluorine-like to hydrogen like, ionic states. The study is motivated by uur proposed method, Resonant Theranosticsb,C (RT) for biomedical appliations, which aims to find narrow band X-ray energy that corresponds to resonant photo-absorption and leads to emission of Auger electrons. As the next step of the RT method we will also report on experimental results on producing monochromatic X-rays, targeted to the resonant energy, from the wide band Bremstruhlung radiation of a conventional X-ray source. Partially support: DOE, Computational Facility: Ohio Supercomputer Center, Columbus, Ohio. "Resonant X-Ray Enhancement of the Auger Effect in High-Z atoms, molecules, and Nanoparticles: Biomedical Applications", A.K. Pradhan, S.N. Nahar, M. Montenegro, Yan Yu, H.L. Zhang, C. Sur, M. Mrozik, R.M. Pitzer, J. of Phys. Chem. A, 113 (2009), 12356. "Monte Carlo Simulations and Atomic Calculations for Auger Processes in Biomedical Nanotheranostics", M. Montenegro, S. N. Nahar, A. K. Pradhan, Ke Huang, Yan Yu, J. of Phys. Chem. A, 113 (2009), 12364.

Nahar, Sultana N.; Lim, Sara; Pradhan, A. K.; Pitzer, R. M.

2011-06-01

367

Comparison of solar flare X-ray producing and escaping electrons from about 2 to 100 keV  

NASA Technical Reports Server (NTRS)

Using observations from the ISEE-3 spacecraft, the X-ray producing electrons and escaping electons from a solar flare on November 8, 1978 are compared. The instantaneous 5 to 75 keV electron spectrum in the X-ray producing region is computed from the observed bremsstrahlung X-ray spectrum. Assuming that energy loss by Coulomb collisions (thick target) is the dominant electron loss process, the accelerated electron spectrum is obtained. The energy spectrum of the escaping electrons observed from 2 to 100 keV differs significantly from the spectra of the X-ray producing electrons and of the accelerated electrons, even when the energy loss which the escaping electrons experienced during their travel from the sun to the earth is taken into account. The observations are consistent with a model where the escaping electons come from an extended X-ray producing region, which ranges from the chromosphere to high in the corona. In this model, the low energy escaping electrons (2-10 keV) come from the higher part of the extended X-ray source where the overlying column density is low, while the high energy electrons (20-100 keV) come from the entire X-ray source.

Pan, L.-D.; Lin, R. P.; Kane, S. R.

1984-01-01

368

X-ray transition radiation in a solid-state superlattice: photoabsorption, electron scattering, and radiation optimization.  

PubMed

Soft x rays are generated when low-energy electron beams traverse a solid-state superlattice. We investigate the influence of x-ray absorption and electron scattering losses on the maximum power radiated, the required electron energy, and the optimum total thickness of the superlattice. We show that a moderate increase in the electron-beam energy compensates for the losses due to photoabsorption and electron scattering. PMID:19741909

Law, C T; Kaplan, A E

1987-11-01

369

Quantitative Analysis of Mt. St. Helens Ash by X-Ray Diffraction and X-Ray Fluorescence Spectrometry  

Microsoft Academic Search

A quantitative study by x-ray diffraction, optical polarizing microscopy, and x-ray fluorescence spectrometry of fallout and ambient ash from three Mt. St. Helens eruptions has revealed a consistent picture of the mineralogical and elemental composition. The major components observed are amorphous glass, plagioclase of about An50 composition, minor amounts of quartz and other SiO2 polymorphs, as well as ferromagnesian constituents

Briant L. Davis; L. Ronald Johnson; Dana T. Griffen; William Revell Phillips; Robert K. Stevens; David Maughan

1981-01-01

370

THE XMM-NEWTON/EPIC X-RAY LIGHT CURVE ANALYSIS OF WR 6  

SciTech Connect

We obtained four pointings of over 100 ks each of the well-studied Wolf-Rayet star WR 6 with the XMM-Newton satellite. With a first paper emphasizing the results of spectral analysis, this follow-up highlights the X-ray variability clearly detected in all four pointings. However, phased light curves fail to confirm obvious cyclic behavior on the well-established 3.766 day period widely found at longer wavelengths. The data are of such quality that we were able to conduct a search for event clustering in the arrival times of X-ray photons. However, we fail to detect any such clustering. One possibility is that X-rays are generated in a stationary shock structure. In this context we favor a corotating interaction region (CIR) and present a phenomenological model for X-rays from a CIR structure. We show that a CIR has the potential to account simultaneously for the X-ray variability and constraints provided by the spectral analysis. Ultimately, the viability of the CIR model will require both intermittent long-term X-ray monitoring of WR 6 and better physical models of CIR X-ray production at large radii in stellar winds.

Ignace, R. [Department of Physics and Astronomy, East Tennessee State University, Johnson City, TN 37663 (United States); Gayley, K. G. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52245 (United States); Hamann, W.-R.; Oskinova, L. M. [Institute for Physics and Astronomy, University Potsdam, D-14476 Potsdam (Germany); Huenemoerder, D. P. [Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, 70 Vassar Street, Cambridge, MA 02139 (United States); Pollock, A. M. T. [European Space Agency XMM-Newton Science Operations Centre, European Space Astronomy Centre, Apartado 78, Villanueva de la Cañada, E-28691 Madrid (Spain); McFall, M., E-mail: ignace@etsu.edu [Department of Physics, 191 W. Woodruff Avenue, Ohio State University, Columbus, OH 43210 (United States)

2013-09-20

371

Iron speciation in human cancer cells by K-edge total reflection X-ray fluorescence-X-ray absorption near edge structure analysis  

NASA Astrophysics Data System (ADS)

X-ray absorption near edge structure (XANES) analysis in combination with synchrotron radiation induced total reflection X-ray fluorescence (SR-TXRF) acquisition was used to determine the oxidation state of Fe in human cancer cells and simultaneously their elemental composition by applying a simple sample preparation procedure consisting of pipetting the cell suspension onto the quartz reflectors. XANES spectra of several inorganic and organic iron compounds were recorded and compared to that of different cell lines. The XANES spectra of cells, independently from the phase of cell growth and cell type were very similar to that of ferritin, the main Fe store within the cell. The spectra obtained after CoCl 2 or NiCl 2 treatment, which could mimic a hypoxic state of cells, did not differ noticeably from that of the ferritin standard. After 5-fluorouracil administration, which could also induce an oxidative-stress in cells, the absorption edge position was shifted toward higher energies representing a higher oxidation state of Fe. Intense treatment with antimycin A, which inhibits electron transfer in the respiratory chain, resulted in minor changes in the spectrum, resembling rather the N-donor Fe-?,?'-dipyridyl complex at the oxidation energy of Fe(III), than ferritin. The incorporation of Co and Ni in the cells was followed by SR-TXRF measurements.

Polgári, Zs.; Meirer, F.; Sasamori, S.; Ingerle, D.; Pepponi, G.; Streli, C.; Rickers, K.; Réti, A.; Budai, B.; Szoboszlai, N.; Záray, G.

2011-03-01

372

Angular distributions of X-rays emitted following L3 ionization of Au atoms by electron impact  

NASA Astrophysics Data System (ADS)

The angular distributions of Au L?, L?, and Ll X-rays at forward angles 0°???25° emitted following 15 keV electron impact have been measured in order to investigate the degree of induced alignment of the L3 subshell vacancies. After corrections for absorption of the characteristic X-rays within the Au target, our results suggest that the angular distributions of the L? and L? X-rays are essentially isotropic, as no anisotropy was observed in our data outside of experimental uncertainties. However, the results of our experiments suggest that the angular distribution of the Au Ll X-rays may be weakly anisotropic.

Sestric, G.; Ferguson, S.; Wright, I.; Williams, S.

2014-09-01

373

Theoretical study of Raman chirped adiabatic passage by X-ray absorption spectroscopy: highly excited electronic states and rotational effects.  

PubMed

Raman Chirped Adiabatic Passage (RCAP) is an efficient method to climb the vibrational ladder of molecules. It was shown on the example of fixed-in-space HCl molecule that selective vibrational excitation can thus be achieved by RCAP and that population transfer can be followed by X-ray Photoelectron spectroscopy [S. Engin, N. Sisourat, P. Selles, R. Taïeb, and S. Carniato, Chem. Phys. Lett. 535, 192-195 (2012)]. Here, in a more detailed analysis of the process, we investigate the effects of highly excited electronic states and of molecular rotation on the efficiency of RCAP. Furthermore, we propose an alternative spectroscopic way to monitor the transfer by means of X-ray absorption spectra. PMID:24952537

Engin, Selma; Sisourat, Nicolas; Selles, Patricia; Taïeb, Richard; Carniato, Stéphane

2014-06-21

374

Theoretical study of Raman chirped adiabatic passage by X-ray absorption spectroscopy: Highly excited electronic states and rotational effects  

NASA Astrophysics Data System (ADS)

Raman Chirped Adiabatic Passage (RCAP) is an efficient method to climb the vibrational ladder of molecules. It was shown on the example of fixed-in-space HCl molecule that selective vibrational excitation can thus be achieved by RCAP and that population transfer can be followed by X-ray Photoelectron spectroscopy [S. Engin, N. Sisourat, P. Selles, R. Taïeb, and S. Carniato, Chem. Phys. Lett. 535, 192-195 (2012)]. Here, in a more detailed analysis of the process, we investigate the effects of highly excited electronic states and of molecular rotation on the efficiency of RCAP. Furthermore, we propose an alternative spectroscopic way to monitor the transfer by means of X-ray absorption spectra.

Engin, Selma; Sisourat, Nicolas; Selles, Patricia; Taïeb, Richard; Carniato, Stéphane

2014-06-01

375

Transverse pulse shaping and optimization of a tapered hard X-ray free electron laser  

E-print Network

Multidimensional optimization schemes for TW hard X-Ray free electron lasers are applied to the cases of transversely uniform and parabolic electron beam distributions and compared to examples of transversely Gaussian beams. The optimizations are performed for a $200$m undulator and a resonant wavelength of $\\lambda_r=1.5\\AA $ using the fully 3-dimensional FEL particle code GENESIS. Time dependent simulations showed that the maximum radiation power is larger for flatter transverse distributions due to enhanced optical guiding in the tapered section of the undulator. For a transversely Gaussian beam the maximum output power was found to be $\\text{P}_{max}$=$1.56$ TW compared to $2.26$ TW for the parabolic case and $2.63$ TW for the uniform case. Spectral data also showed a 30-70$\\%$ reduction in energy deposited in the sidebands for the uniform and parabolic beams compared with a Gaussian. An analysis of the maximum power as a function of detuning from resonance shows that redshifting the central wavelength by...

Emma, Claudio; Wu, Juhao

2014-01-01

376

Probing bulk electronic structure with hard X-ray angle-resolved photoemission  

NASA Astrophysics Data System (ADS)

Traditional ultraviolet/soft X-ray angle-resolved photoemission spectroscopy (ARPES) may in some cases be too strongly influenced by surface effects to be a useful probe of bulk electronic structure. Going to hard X-ray photon energies and thus larger electron inelastic mean-free paths should provide a more accurate picture of bulk electronic structure. We present experimental data for hard X-ray ARPES (HARPES) at energies of 3.2 and 6.0?keV. The systems discussed are W, as a model transition-metal system to illustrate basic principles, and GaAs, as a technologically-relevant material to illustrate the potential broad applicability of this new technique. We have investigated the effects of photon wave vector on wave vector conservation, and assessed methods for the removal of phonon-associated smearing of features and photoelectron diffraction effects. The experimental results are compared to free-electron final-state model calculations and to more precise one-step photoemission theory including matrix element effects.

Gray, A. X.; Papp, C.; Ueda, S.; Balke, B.; Yamashita, Y.; Plucinski, L.; Minár, J.; Braun, J.; Ylvisaker, E. R.; Schneider, C. M.; Pickett, W. E.; Ebert, H.; Kobayashi, K.; Fadley, C. S.

2011-10-01

377

Analysis of microroughness evolution in X-ray astronomical multilayer mirrors by surface topography with the MPES program and by X-ray scattering  

NASA Astrophysics Data System (ADS)

Future hard X-ray telescopes (e.g. SIMBOL-X and Constellation-X) will make use of hard X-ray optics with multilayer coatings, with angular resolutions comparable to the achieved ones in the soft X-rays. One of the crucial points in X-ray optics, indeed, is multilayer interfacial microroughness that causes effective area reduction and X-Ray Scattering (XRS). The latter, in particular, is responsible for image quality degradation. Interfacial smoothness deterioration in multilayer deposition processes is commonly observed as a result of substrate profile replication and intrinsic random deposition noise. For this reason, roughness growth should be carefully investigated by surface topographic analysis, X-ray reflectivity and XRS measurements. It is convenient to express the roughness evolution in terms of interface Power Spectral Densities (PSD), that are directly related to XRS and, in turn, in affecting the optic HEW (Half Energy Width). In order to interpret roughness amplification and to help us to predict the imaging performance of hard X-ray optics, we have implemented a well known kinetic continuum equation model in a IDL language program (MPES, Multilayer PSDs Evolution Simulator), allowing us the determination of characteristic growth parameters in multilayer coatings. In this paper we present some results from analysis we performed on several samples coated with hard X-ray multilayers (W/Si, Pt/C, Mo/Si) using different deposition techniques. We show also the XRS predictions resulting from the obtained modelizations, in comparison to the experimental XRS measurements performed at the energy of 8.05 keV.

Canestrari, R.; Spiga, D.; Pareschi, G.

2006-06-01

378

Potential applications of polycapillary optics to polarized beam X-ray fluorescence analysis  

Microsoft Academic Search

The Polarized beam X-ray fluorescence (XRF) technique has potential applications in elemental analysis in materials analysis and in-vivo. In this work, first micro X-ray fluorescence (MXRF) measurements were done using a focusing lens. Polarization can be used to reduce the background, to give a better minimum detection limit. Polarizing the beam, using scattering has a disadvantage of low intensity and

Abrar M. Hussain

2006-01-01

379

Assessment of Atmospheric Pollutant Fluxes to the North Sea by X-Ray Emission Analysis  

NASA Astrophysics Data System (ADS)

The aim of this work was to estimate quantitatively from field measurements the atmospheric supply of trace elements into the North Sea and to evaluate the nature of the aerosol particles responsible for this flux. The indirect deposition calculations in this work are based on the measured aerosol concentrations in the lower troposphere of the North Sea. Over a period of five years (1989-1994) aerosols were collected from an aircraft, on board of research vessels, from a platform and at the Belgian coast (pier of Blankenberge, about 100 m from the shore). Different ways of aerosol collection have been invoked; sampling was done on Nuclepore filters and quartz discs, by different types of cascade impactors and by the membrane type of filters. For all ship- and platform-sampling, the sampling equipment was placed in a wind-tunnel, with a forced internal air flow, which orients itself towards the wind by a wind vane, so that particles were collected isokinetically with a high efficiency. Various sensitive multi-element bulk and single particle techniques were implemented to measure the airborne concentrations and size distributions of micro- and trace -elements over the North Sea, namely: energy-dispersive X-ray fluorescence (EDXRF) and total-reflection X-ray fluorescence (TXRF), proton-induced X-ray emission (PIXE), anodic stripping voltametry (ASV), electron-probe X-ray microanalysis (EPXMA) and nuclear microprobe (NMP) combined with PIXE. The resulting huge data set was handled by multivariate techniques like principal component analysis (PCA) and non-linear mapping (NLM). The NMP combined with PIXE was successfully applied to the analysis of individual giant aerosol particles for their elemental composition down to absolute masses of 50 fg for some trace metals. Such single particle analysis combined with multivariate numerical analysis reveals three major particle types: (1) particles dominated by (Na)Cl, S, K and Ca, apparently seasalt, aged seasalt and gypsum, (2) particles with relatively high contents of Cr, Fe, Ni, Zn, V and Ti, probably fly ash and (3) mixed or aggregated marine/continental particles, which are internally heterogenous and contain e.g. Cr and seasalt elements in separated parts of the same giant particle. Collision of fly ash particles with abundant seaspray might explain the increased deposition velocities during stormy conditions. (Abstract shortened by UMI.).

Injuk, Jasna

1995-01-01

380

Undulator commissioning by characterization of radiation in x-ray free electron lasers  

NASA Astrophysics Data System (ADS)

In x-ray free electron lasers (XFELs) where a long undulator composed of many segments is installed, there exist a number of error sources to reduce the FEL gain such as the trajectory error, K value discrepancy, and phase mismatch, which are related to the segmented-undulator structure. Undulator commissioning, which refers to the tuning and alignment processes to eliminate the possible error sources, is thus an important step toward realization of lasing. In the SPring-8 angstrom compact free electron laser (SACLA) facility, the undulator commissioning has been carried out by means of characterization of x-ray radiation, i.e., measurements of the spatial and spectral profiles of monochromatized spontaneous undulator radiation as well as by probing the FEL intensity. The achieved tuning and alignment accuracies estimated from the statistics of actual measurements in SACLA show the effectiveness of this commissioning scheme.

Tanaka, Takashi; Goto, Shunji; Hara, Toru; Hatsui, Takaki; Ohashi, Haruhiko; Togawa, Kazuaki; Yabashi, Makina; Tanaka, Hitoshi

2012-11-01

381

Few-cycle pulse generation in an x-ray free-electron laser.  

PubMed

A method is proposed to generate trains of few-cycle x-ray pulses from a free-electron laser (FEL) amplifier via a compact "afterburner" extension consisting of several few-period undulator sections separated by electron chicane delays. Simulations show that in the hard x ray (wavelength ~0.1 nm; photon energy ~10 keV) and with peak powers approaching normal FEL saturation (GW) levels, root mean square pulse durations of 700 zs may be obtained. This is approximately two orders of magnitude shorter than that possible for normal FEL amplifier operation. The spectrum is discretely multichromatic with a bandwidth envelope increased by approximately 2 orders of magnitude over unseeded FEL amplifier operation. Such a source would significantly enhance research opportunity in atomic dynamics and push capability toward nuclear dynamics. PMID:23521266

Dunning, D J; McNeil, B W J; Thompson, N R

2013-03-01

382

Polarization control of an X-ray free-electron laser with a diamond phase retarder.  

PubMed

A diamond phase retarder was applied to control the polarization states of a hard X-ray free-electron laser (XFEL) in the photon energy range 5-20 keV. The horizontal polarization of the XFEL beam generated from the planar undulators of the SPring-8 Angstrom Compact Free-Electron Laser (SACLA) was converted into vertical or circular polarization of either helicity by adjusting the angular offset of the diamond crystal from the exact Bragg condition. Using a 1.5 mm-thick crystal, a high degree of circular polarization, 97%, was obtained for 11.56 keV monochromatic X-rays, whereas the degree of vertical polarization was 67%, both of which agreed with the estimations including the energy bandwidth of the Si 111 beamline monochromator. PMID:24763633

Suzuki, Motohiro; Inubushi, Yuichi; Yabashi, Makina; Ishikawa, Tetsuya

2014-05-01

383

X-ray absorption study of the electronic structure of Mn-doped amorphous Si  

SciTech Connect

The electronic structure of Mn in amorphous Si (a-Mn{sub x}Si{sub 1?x}) is studied by X-ray absorption spectroscopy at the Mn L{sub 3,2} edges for x = 0.005-0.18. Except the x = 0.005 sample, which shows a slight signature of Mn{sup 2+} atomic multiplets associated with a local Mn moment, all samples have broad and featureless L{sub 3,2} absorption peaks, corresponding to an itinerant state for all 3d electrons. The broad X-ray absorption spectra exclude the possibility of a localized 3d moment and explain the unexpectedly quenched Mn moment in this magnetically-doped amorphous semiconductor. Such a fully delocalized d state of Mn dopant in Si has not been previously suggested.

Arenholz, Elke; Zeng, Li; Huegel, A.; Helgren, E.; Hellman, F.; Piamonteze, C.; Arenholz, E.

2008-03-08

384

X-ray photoemission electron microscopy, a tool for the investigation of complex magnetic structures.  

SciTech Connect

X-ray Photoemission Electron Microscopy unites the chemical specificity and magnetic sensitivity of soft x-ray absorption techniques with the high spatial resolution of electron microscopy. The discussed instrument possesses a spatial resolution of better than 50 nm and is located at a bending magnet beamline at the Advanced Light Source, providing linearly and circularly polarized radiation between 250 and 1300 eV. We will present examples which demonstrate the power of this technique applied to problems in the field of thin film magnetism. The chemical and elemental specificity is of particular importance for the study of magnetic exchange coupling because it allows separating the signal of the different layers and interfaces in complex multi-layered structures.

Scholl, Andreas; Ohldag, Hendrik; Nolting, Frithjof; Stohr, Joachim; Padmore, Howard A.

2001-08-30

385

An Introduction to the Scope, Potential and Applications of X-ray Analysis  

NSDL National Science Digital Library

This site from Michael Laing at the University of Natal provides an introduction to X-ray crystallography and the applications of various techniques. A discussion of basic crystallography leads into X-ray diffraction and a variety of X-ray techniques, including Laue, powder, and single crystal methods. Other topics include difffractometers, the reciprocal lattice explorer, and moving crystal and moving film methods such as the rotation, precession and Weissenberg methods. A section on applications and analysis of these methods is also included. Diagrams, tables and graphs support the text.

Laing, Michael; Crystallography, International U.

386

An atomic layer deposition chamber for in situ x-ray diffraction and scattering analysis  

NASA Astrophysics Data System (ADS)

The crystal structure of thin films grown by atomic layer deposition (ALD) will determine important performance properties such as conductivity, breakdown voltage, and catalytic activity. We report the design of an atomic layer deposition chamber for in situ x-ray analysis that can be used to monitor changes to the crystal structural during ALD. The application of the chamber is demonstrated for Pt ALD on amorphous SiO2 and SrTiO3 (001) using synchrotron-based high resolution x-ray diffraction, grazing incidence x-ray diffraction, and grazing incidence small angle scattering.

Geyer, Scott M.; Methaapanon, Rungthiwa; Johnson, Richard W.; Kim, Woo-Hee; Van Campen, Douglas G.; Metha, Apurva; Bent, Stacey F.

2014-05-01

387

An atomic layer deposition chamber for in situ x-ray diffraction and scattering analysis.  

PubMed

The crystal structure of thin films grown by atomic layer deposition (ALD) will determine important performance properties such as conductivity, breakdown voltage, and catalytic activity. We report the design of an atomic layer deposition chamber for in situ x-ray analysis that can be used to monitor changes to the crystal structural during ALD. The application of the chamber is demonstrated for Pt ALD on amorphous SiO2 and SrTiO3 (001) using synchrotron-based high resolution x-ray diffraction, grazing incidence x-ray diffraction, and grazing incidence small angle scattering. PMID:24880424

Geyer, Scott M; Methaapanon, Rungthiwa; Johnson, Richard W; Kim, Woo-Hee; Van Campen, Douglas G; Metha, Apurva; Bent, Stacey F

2014-05-01

388

Advances in X-Ray Chemical Analysis, Japan, 41 (2010) ISSN 0911-7806 CSI, ICXOM X  

E-print Network

Advances in X-Ray Chemical Analysis, Japan, 41 (2010) ISSN 0911-7806 © CSI, ICXOM X Reports on International conferences (CSI at Budapest, ICXOM at Karlsruhe, and 2nd International Conference on X-Ray Analysis in Mongolia) Jun KAWAI #12;#12;41 219 CSI ICXOM X Adv. X-Ray. Chem. Anal., Japan 41, pp.219

Jun, Kawai

389

Design optimization for an X-ray free electron laser driven by SLAC LINAC  

Microsoft Academic Search

I present a design study for an X-ray Free Electron Laser (FEL)driven by the SLAC linac. The study assumes the FEL is basedon Self-Amplified Spontaneous Emission (SASE) and lasing isachieved in a single pass of a high current, high brightness electronbeam through a long wiggler. Following a brief review ofthe fundamentals of SASE, I will provide without derivation acollection of

Ming Xie; Lawrence Berkeley

1996-01-01

390

Simulation Studies of the X-Ray Free-Electron Laser Oscillator  

Microsoft Academic Search

Simulations of the x-ray free-electron laser (FEL) oscillator are presented that include transverse effects and realistic Bragg crystal properties with the two-dimensional code GINGER. In the present cases considered the radiation divergence is much narrower than the crystal acceptance, and the numerical algorithm can be simplified by ignoring the finite angular bandwidth of the crystal. In this regime GINGER shows

R. R. Lindberg; Y. Shydko; K.-J Kim; W. M. Fawley

2009-01-01

391

Investigating strongly correlated electron systems with synchrotron X-ray diffraction at LNLS  

Microsoft Academic Search

Recent X-ray diffraction measurements of strongly correlated electron systems performed at the Brazilian synchrotron light laboratory (LNLS) are described. These include the observation, by means of high-resolution powder diffraction, of small structural distortions likely associated with orbital ordering phenomena in transition-metal oxides, and magnetic diffraction of the intermetallic series GdmMnIn3m+2n (M=Rh or Ir). These preliminary results illustrate the opportunities offered

Eduardo Granado

2004-01-01

392

X-ray spectral investigation of the electronic structure of the ClO  

Microsoft Academic Search

The electronic structure of the C104 anion derived from the x-ray fluorescent spectra of the chlorine and oxygen is discussed. It has been shown experimentally that the 3d orbitals of chlorine participate in 3dlr (C1)-2pr r (0) and 3d a (C1)-2s (0) bonds, From a comparison of the relative intensities in the L spectrum of the chlorine, the relative contributions

A. P. Sadovskii; L. N. Mazalov; G. N. Dolenko; A. A. Krasnoperova; V. D. Yumatov

1974-01-01

393

Contemporary X-ray electron-density studies using synchrotron radiation  

PubMed Central

Synchrotron radiation has many compelling advantages over conventional radiation sources in the measurement of accurate Bragg diffraction data. The variable photon energy and much higher flux may help to minimize critical systematic effects such as absorption, extinction and anomalous scattering. Based on a survey of selected published results from the last decade, the benefits of using synchrotron radiation in the determination of X-ray electron densities are discussed, and possible future directions of this field are examined.

J?rgensen, Mads R. V.; Hathwar, Venkatesha R.; Bindzus, Niels; Wahlberg, Nanna; Chen, Yu-Sheng; Overgaard, Jacob; Iversen, Bo B.

2014-01-01

394

Electronic configuration of cerium in amorphous alloys investigated by x-ray absorption spectroscopy  

Microsoft Academic Search

X-ray absorption-edge measurements were used to investigate the electronic configuration of cerium in different series of amorphous alloys, namely the Ce-Si alloys and the intermetallic Ce-Ni and Ce-Co alloys. The effect of structural disorder is evaluated from a comparison of our data on amorphous alloys with those obtained for compositionally related crystalline compounds. While the LIII absorption edge for CeSi2

D. Malterre; G. Krill; J. Durand; G. Marchal; M. F. Ravet

1986-01-01

395

Calcium in smooth muscle sarcoplasmic reticulum in situ. Conventional and X-ray analytical electron microscopy  

PubMed Central

Numerous electron-opaque deposits appear in the SR of the relaxed smooth muscle cells of the guinea pig Taenia coli that had been treated, before fixation, with a depolarizing medium containing oxalate to precipitate calcium ions in situ. X-ray spectra obtained by spot and line-scanning analyses of these deposits in situ show characteristic calcium signals, thus providing direct evidence for calcium accumulation inside the sarcoplasmic reticulum of smooth muscle. PMID:1202028

1975-01-01

396

Confinement of hot, hard x-ray producing electrons in solar flares  

Microsoft Academic Search

Possible thermal models for solar, hard X-ray emission, consisting of small volumes in which the electrons are rapidly heated to 4 x 10⁸ K, are examined to determine under what conditions such models can be more efficient than nonthermal models. The primary energy-loss mechanism in these models is source expansion due to heat conduction which deviates from its classical value

D. F. Smith; C. G. Lilliequist

1979-01-01

397

The electronic structure of uranium dioxide: an oxygen Kedge x-ray absorption study  

Microsoft Academic Search

The O K-edge x-ray absorption near edge structure (XANES) spectrum of 0953-8984\\/9\\/43\\/022\\/img8 is presented and interpreted. A comparison with that corresponding to 0953-8984\\/9\\/43\\/022\\/img9 is made. First-principles-based calculations using the LSDA+U approach allows us to link each feature present in the spectra to the specific atomic arrangement and electronic structure of the compound. The structures at the edge originate from oxygen

F. Jollet; T. Petit; S. Gota; N. Thromat; M. Gautier-Soyer; A. Pasturel

1997-01-01

398

Combined X-ray and electron microscopy study of MgB2 powders, wires and tapes  

NASA Astrophysics Data System (ADS)

MgB2 wires, tapes and bulk samples produced within the EU-funded HIPERMAG project have been studied by a combination of X-ray diffraction and electron microscopy. The reaction layers forming at the interface between the ceramic core and Fe or Ni sheaths can be studied with both methods. The complementary techniques enable to study both the microstructure and the formation kinetics of the interface layers. Grain sizes can be determined either by direct observation or by analysis of the shape of X-ray diffraction peaks. Electron microscopy can detect B-rich secondary phases and phases present in small fractions that are not accessible by x-ray diffraction. On the other hand, synchrotron diffraction provides a fast and non-destructive method for the study of the main phases and their development during in-situ, high-temperature investigations. The combination of the two techniques is a very valuable tool for the optimisation of MgB2-based superconducting material.

Grivel, J. C.; Eibl, O.; Birajdar, B.; Andersen, N. H.; Abrahamsen, A.; Pinholt, R.; Grasso, G.; Hässler, W.; Herrmann, M.; Perner, O.; Rodig, C.; Pachla, W.; Ková, P.; Husek, I.; Mikheenko, P.; Abell, S.; Homeyer, J.

2006-06-01

399

Compact X-ray Free Electron Laser from a Laser-plasma Accelerator using a Transverse Gradient Undulator  

SciTech Connect

Compact laser-plasma accelerators can produce high energy electron beams with low emittance, high peak current but a rather large energy spread. The large energy spread hinders the potential applications for coherent FEL radiation generation. In this paper, we discuss a method to compensate the effects of beam energy spread by introducing a transverse field variation into the FEL undulator. Such a transverse gradient undulator together with a properly dispersed beam can greatly reduce the effects of electron energy spread and jitter on FEL performance. We present theoretical analysis and numerical simulations for SASE and seeded extreme ultraviolet and soft x-ray FELs based on laser plasma accelerators.

Huang, Zhirong; Ding, Yuantao; /SLAC; Schroeder, Carl B.; /LBL, Berkeley

2012-09-13

400

Electron yield soft X-ray photoabsorption spectroscopy under normal ambient-pressure conditions  

PubMed Central

Ambient-pressure soft X-ray photoabsorption spectroscopy (XAS) was demonstrated to be applicable to the chemical analysis of hydrated transition-metal compounds. For this purpose, even under ambient-pressure conditions, electron yield detection XAS (EY-XAS), based on a simple drain-current set-up, was used to overcome a weakness in fluorescence yield detection XAS (FY-XAS), which does not give a pure soft XAS. The feasibility of EY-XAS was investigated and it was clarified that the EY-XAS under ambient-pressure conditions corresponds to the mixed data of the total EY and conversion EY spectra. Normal ambient-pressure EY-XAS analysis was applied to anhydrous (CoCl2) and to hydrated (CoCl2·6H2O) cobalt chloride at the Co L 23-edge. The present measurements demonstrated the ability to unambiguously distinguish the different chemical states of cobalt ions, relying upon spectral differences that indicate octahedral/quasi-octahedral structural changes as a result of hydration/dehydration reactions. PMID:23592620

Tamenori, Yusuke

2013-01-01

401

Electron yield soft X-ray photoabsorption spectroscopy under normal ambient-pressure conditions.  

PubMed

Ambient-pressure soft X-ray photoabsorption spectroscopy (XAS) was demonstrated to be applicable to the chemical analysis of hydrated transition-metal compounds. For this purpose, even under ambient-pressure conditions, electron yield detection XAS (EY-XAS), based on a simple drain-current set-up, was used to overcome a weakness in fluorescence yield detection XAS (FY-XAS), which does not give a pure soft XAS. The feasibility of EY-XAS was investigated and it was clarified that the EY-XAS under ambient-pressure conditions corresponds to the mixed data of the total EY and conversion EY spectra. Normal ambient-pressure EY-XAS analysis was applied to anhydrous (CoCl2) and to hydrated (CoCl2·6H2O) cobalt chloride at the Co L23-edge. The present measurements demonstrated the ability to unambiguously distinguish the different chemical states of cobalt ions, relying upon spectral differences that indicate octahedral/quasi-octahedral structural changes as a result of hydration/dehydration reactions. PMID:23592620

Tamenori, Yusuke

2013-05-01

402

Focusing of X-ray free-electron laser pulses with reflective optics  

NASA Astrophysics Data System (ADS)

X-ray free-electron lasers produce intense femtosecond pulses that have applications in exploring new frontiers in science. The unique characteristics of X-ray free-electron laser radiation can be enhanced significantly using focusing optics. However, with such an optical device, even a slight deviation from the ideal design can lead to considerable errors in the focusing properties. Here, we present reflective optics comprising elliptically figured mirrors with nanometre accuracy to preserve a coherent wavefront, successfully focusing a 10 keV X-ray free-electron laser to the small area of 0.95 × 1.20 µm2. The near 100% efficiency of this arrangement allows an enormous 40,000-fold increase in the fluence to a power density of 6 × 1017 W cm-2. This achievement is directly applicable to the generation of a nanometre-size beam with an extreme power density of >1 × 1022 W cm-2, which will play a crucial role in the advance of microscopic research towards ultimate ångstrom resolution, as well as in the development of nonlinear optical sciences under extreme conditions.

Yumoto, Hirokatsu; Mimura, Hidekazu; Koyama, Takahisa; Matsuyama, Satoshi; Tono, Kensuke; Togashi, Tadashi; Inubushi, Yuichi; Sato, Takahiro; Tanaka, Takashi; Kimura, Takashi; Yokoyama, Hikaru; Kim, Jangwoo; Sano, Yasuhisa; Hachisu, Yousuke; Yabashi, Makina; Ohashi, Haruhiko; Ohmori, Hitoshi; Ishikawa, Tetsuya; Yamauchi, Kazuto

2013-01-01

403

Optical control of hard X-ray polarization by electron injection in a laser wakefield accelerator.  

PubMed

Laser-plasma particle accelerators could provide more compact sources of high-energy radiation than conventional accelerators. Moreover, because they deliver radiation in femtosecond pulses, they could improve the time resolution of X-ray absorption techniques. Here we show that we can measure and control the polarization of ultra-short, broad-band keV photon pulses emitted from a laser-plasma-based betatron source. The electron trajectories and hence the polarization of the emitted X-rays are experimentally controlled by the pulse-front tilt of the driving laser pulses. Particle-in-cell simulations show that an asymmetric plasma wave can be driven by a tilted pulse front and a non-symmetric intensity distribution of the focal spot. Both lead to a notable off-axis electron injection followed by collective electron-betatron oscillations. We expect that our method for an all-optical steering is not only useful for plasma-based X-ray sources but also has significance for future laser-based particle accelerators. PMID:24026068

Schnell, Michael; Sävert, Alexander; Uschmann, Ingo; Reuter, Maria; Nicolai, Maria; Kämpfer, Tino; Landgraf, Björn; Jäckel, Oliver; Jansen, Oliver; Pukhov, Alexander; Kaluza, Malte Christoph; Spielmann, Christian

2013-01-01

404

Optical control of hard X-ray polarization by electron injection in a laser wakefield accelerator  

PubMed Central

Laser-plasma particle accelerators could provide more compact sources of high-energy radiation than conventional accelerators. Moreover, because they deliver radiation in femtosecond pulses, they could improve the time resolution of X-ray absorption techniques. Here we show that we can measure and control the polarization of ultra-short, broad-band keV photon pulses emitted from a laser-plasma-based betatron source. The electron trajectories and hence the polarization of the emitted X-rays are experimentally controlled by the pulse-front tilt of the driving laser pulses. Particle-in-cell simulations show that an asymmetric plasma wave can be driven by a tilted pulse front and a non-symmetric intensity distribution of the focal spot. Both lead to a notable off-axis electron injection followed by collective electron–betatron oscillations. We expect that our method for an all-optical steering is not only useful for plasma-based X-ray sources but also has significance for future laser-based particle accelerators. PMID:24026068

Schnell, Michael; Savert, Alexander; Uschmann, Ingo; Reuter, Maria; Nicolai, Maria; Kampfer, Tino; Landgraf, Bjorn; Jackel, Oliver; Jansen, Oliver; Pukhov, Alexander; Kaluza, Malte Christoph; Spielmann, Christian

2013-01-01

405

DIFFUSE HARD X-RAY EMISSION IN STARBURST GALAXIES AS SYNCHROTRON FROM VERY HIGH ENERGY ELECTRONS  

SciTech Connect

The origin of the diffuse hard X-ray (2-10 keV) emission from starburst galaxies is a long-standing problem. We suggest that synchrotron emission of 10-100 TeV electrons and positrons (e {sup {+-}}) can contribute to this emission, because starbursts have strong magnetic fields. We consider three sources of e {sup {+-}} at these energies: (1) primary electrons directly accelerated by supernova remnants, (2) pionic secondary e {sup {+-}} created by inelastic collisions between cosmic ray (CR) protons and gas nuclei in the dense interstellar medium of starbursts, and (3) pair e {sup {+-}} produced between the interactions between 10 and 100 TeV {gamma}-rays and the intense far-infrared (FIR) radiation fields of starbursts. We create one-zone steady-state models of the CR population in the Galactic center (R {<=} 112 pc), NGC 253, M82, and Arp 220's nuclei, assuming a power-law injection spectrum for electrons and protons. We consider different injection spectral slopes, magnetic field strengths, CR acceleration efficiencies, and diffusive escape times, and include advective escape, radiative cooling processes, and secondary and pair e {sup {+-}}. We compare these models to extant radio and GeV and TeV {gamma}-ray data for these starbursts, and calculate the diffuse synchrotron X-ray and inverse Compton (IC) luminosities of these starbursts in the models which satisfy multiwavelength constraints. If the primary electron spectrum extends to {approx}PeV energies and has a proton/electron injection ratio similar to the Galactic value, we find that synchrotron emission contributes 2%-20% of their unresolved, diffuse hard X-ray emission. However, there is great uncertainty in this conclusion because of the limited information on the CR electron spectrum at these high energies. IC emission is likewise a minority of the unresolved X-ray emission in these starbursts, from 0.1% in the Galactic center to 10% in Arp 220's nuclei, with the main uncertainty being the starbursts' magnetic field. We also model generic starbursts, including submillimeter galaxies, in the context of the FIR-X-ray relation, finding that anywhere between 0% and 16% of the total hard X-ray emission is synchrotron for different parameters, and up to 2% in the densest starbursts assuming an E {sup -2.2} injection spectrum and a diffusive escape time of 10 Myr (E/3 GeV){sup -1/2} (h/100 pc). Neutrino observations by IceCube and TeV {gamma}-ray data from HESS, VERITAS, and CTA can further constrain the synchrotron X-ray emission of starbursts. Our models do not constrain the possibility of hard, second components of primary e {sup {+-}} from sources like pulsars in starbursts, which could enhance the synchrotron X-ray emission further.

Lacki, Brian C. [Institute for Advanced Study, Princeton, NJ 08540 (United States)] [Institute for Advanced Study, Princeton, NJ 08540 (United States); Thompson, Todd A. [Department of Astronomy, The Ohio State University, Columbus, OH 43210 (United States)] [Department of Astronomy, The Ohio State University, Columbus, OH 43210 (United States)

2013-01-01

406

X-ray reflectivity analysis of titanium dioxide thin films grown by cathodic arc deposition.  

PubMed

TiO2 thin films deposited by a vacuum arc on a glass substrate were characterized by X-ray reflectivity (XRR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Several thin films with different amounts of deposited TiO2 mass and different deposition and annealing temperatures were studied. A qualitative analysis of the XRD patterns indicated the presence of the anatase and/or rutile crystalline phases in most of the studied samples. From the analysis of the experimental XRR curves--which exhibited a wide angular range of oscillatory behavior--the thickness, mass density and interface roughness were determined. All XRR patterns were well fitted by modeled curves that assume the presence of a single and homogeneous TiO2 layer over which a very thin H2O layer is adsorbed. The thickest H2O adsorption layers were developed in films with the highest anatase content. Our overall results of the XRR analyses are consistent with those derived from the imaging techniques (SEM and AFM). PMID:24734661

Kleiman, A; Lamas, D G; Craievich, A F; Márquez, A

2014-05-01

407

Compositional analysis of Ceramic Glaze by Laser Induced Breakdown Spectroscopy and Energy Dispersive X-Ray  

NASA Astrophysics Data System (ADS)

Laser induced breakdown spectroscopy (LIBS) has been applied for the analysis of Egyptian Islamic glaze ceramic sample. The sample dating back to Fatimid period (969-1169AD), and collected from Al-Fustat excavation store in Cairo. The analysis of contaminated pottery sample has been performed to draw mapping for the elemental compositions by LIBS technique. LIBS measurements have been done by the fundamental wavelength (1064 nm) of Nd: YAG laser for the elemental analysis and performing the cleaning processes of the pottery sample. In addition, complementary analyses were carried out by scanning electron microscopy linked with energy dispersive X-ray microanalysis (SEM/EDX) to obtain verification of chemical results. The morphological surfaces before and after cleaning has been done by Optical Microscopy (OM).

Khedr, A.; Abdel-kareem, O.; Elnabi, S. H.; Harith, M. A.

2011-09-01

408

State-of-the-art and problems of X-ray diffraction analysis of biomacromolecules  

NASA Astrophysics Data System (ADS)

The state-of-the-art of X-ray diffraction studies of biomacromolecules is briefly characterized, and the challenge imposed by science is discussed. These studies are characterized by a wide scope and extensive use. This field of science is of great interest and is developed in many countries. The main purpose is to solve practical problems in medicine consisting in the design of drugs against various diseases. X-ray diffraction analysis of enzymes brought the pharmaceutical industry to a new level, thus allowing the rational design of drugs against formerly untreatable diseases. Modern X-ray diffraction studies of biomacromolecules laid the basis for a new science called structural biology. This method allows one to solve fundamental problems of physical chemistry for a new state of matter existing in living systems. Here, science poses numerous problems in analysis of X-ray diffraction data on biological macromolecules. Many of theses problems are in their infancy.

Andreeva, N. S.

2006-12-01

409

MaRIE X-Ray Free-Electron Laser Pre-Conceptual Design  

SciTech Connect

The proposed Matter-Radiation Interactions in Extremes (MaRIE) facility at the Los Alamos National Laboratory will include a 50-keV X-Ray Free-Electron Laser (XFEL), a significant extension from planned and existing XFEL facilities. To prevent an unacceptably large energy spread arsing from energy diffusion, the electron beam energy should not exceed 20 GeV, which puts a significant constraint on the beam emittance. A 100-pC baseline design is presented along with advanced technology options to increase the photon flux and to decrease the spectral bandwidth through pre-bunching the electron beam.

Carlsten, Bruce E. [Los Alamos National Laboratory; Barnes, Cris W. [Los Alamos National Laboratory; Bishofberger, Kip A. [Los Alamos National Laboratory; Duffy, Leanne D. [Los Alamos National Laboratory; Heath, Cynthia E. [Los Alamos National Laboratory; Marksteiner, Quinn R. [Los Alamos National Laboratory; Nguyen, Dinh Cong [Los Alamos National Laboratory; Russell, Steven J. [Los Alamos National Laboratory; Ryne, Robert D. [Los Alamos National Laboratory; Sheffield, Richard L. [Los Alamos National Laboratory; Simakov, Evgenya I. [Los Alamos National Laboratory; Yampolsky, Nikolai A. [Los Alamos National Laboratory

2011-01-01

410

Real-space interpretation of x-ray-excited Auger-electron diffraction from Cu(001)  

NASA Astrophysics Data System (ADS)

Angle-resolved Auger-electron diffraction from single-crystal Cu(001) surfaces is reported covering the complete range of emission solid angle between inequivalent mirror planes. Contour maps of the Auger-electron polar and azimuthal angular distribution clearly show the relationship of the measured intensity to low-index real-space crystallographic axes. An experimental approach is described which provides a means for surface-sensitive structure determinations in x-ray-excited electron spectroscopy by comparison to the direct lattice using geometrical constructions.

Li, H.; Tonner, B. P.

1988-03-01

411

Design of a tomographic hard X-ray spectrometer for suprathermal electron studies with ECRH  

SciTech Connect

Electron cyclotron resonance heating (ECRH) and current drive (ECCD), disruptive instability events and sawtooth activity have been demonstrated to produce suprathermal electrons in fusion devices. The importance of these phenomena for fusion reactors renders suprathermal electron generation and dynamics a key topic in the physics of burning plasmas. Here some significant results from the TCV tokamak are briefly reviewed and a preliminary design of a novel tomographic hard X-ray spectrometer proposed for TCV is discussed. The design is aided by simulations of tomographic reconstruction.

Gnesin, S.; Coda, S. [Ecole Polytechnique Federale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom-Confederation Suisse, CH-1015 Lausanne (Switzerland)

2008-03-12

412

Atmospheric Electron-induced X-Ray Spectrometer (AEXS) Instrument Development  

NASA Technical Reports Server (NTRS)

Introduction: This paper describes the progress in data acquisition and establishing the observational capability of the AEXS instrument. The AEXS is a miniature instrument[1-4] based on the excitation of characteristic X-Ray Fluorescence (XRF) and luminescence spectra using a focused electron beam which enables nondestructive evaluation of sample surfaces in planetary ambient atmospheres. In situ operation is obtained through the use of a thin electron transmissive membrane to isolate the vacuum of the AEXS source from the outside ambient atmosphere. Thus eliminating the need for a vacuum pumped sample chamber as is common in all laboratory SEM s. The transmitted electrons impinge on the sample exciting XRF spectra from the irradiated spot on in-situ or collected samples with sub-mm to cm-scale spatial resolution at Mars atmospheric pressure. The AEXS system (Fig 1) consists of a high-energy (>10keV) electron gun encapsulated by the isolation membrane, an XRF detection and analyzer system, and a high voltage power supply. The XRF data are analyzed to determine the elemental abundance for the irradiated spots. The approach to demonstrating a proof of concept of the AEXS has been through 1) demonstrating the viability of microfabricated membranes, 2) assembling AEXS setups with increasingly integrated functional components, and 3) simulating the AEXS observational capabilities. The development of the instrument is described in detail in the poster paper[4] at this conference. This paper focuses on describing the progress of the AEXS instrument to acquire XRF data and using commercially available software to analyze the data streams and determine the accuracy, precision and resolution of the analysis compared to the certified elemental abundance.

Urgiles, E.; Wilcox, J. Z.; Toda, R.; Crisp, J.; George, T.

2005-01-01

413

Computerized X-ray tomography analysis of sandbox models: Examples of thin-skinned thrust systems  

Microsoft Academic Search

Computerized X-ray tomography applied to analog sandbox experiments performed in a normal gravity field makes possible the analysis of the kinematic evolution, as well as the three-dimensional geometry, of models that simulate tectonic deformations. Most of the plastic or viscous analog materials generally used in a normal gravity field for such models have X-ray attenuations compatible with medical scanner images.

Bernard Colletta; Jean Letouzey; Roberto Pinedo; Jean François Ballard; Pascal Balé

1991-01-01

414

X-ray absorption spectroscopy by full-field X-ray microscopy of a thin graphite flake: Imaging and electronic structure via the carbon K-edge  

PubMed Central

Summary We demonstrate that near-edge X-ray-absorption fine-structure spectra combined with full-field transmission X-ray microscopy can be used to study the electronic structure of graphite flakes consisting of a few graphene layers. The flake was produced by exfoliation using sodium cholate and then isolated by means of density-gradient ultracentrifugation. An image sequence around the carbon K-edge, analyzed by using reference spectra for the in-plane and out-of-plane regions of the sample, is used to map and spectrally characterize the flat and folded regions of the flake. Additional spectral features in both ? and ? regions are observed, which may be related to the presence of topological defects. Doping by metal impurities that were present in the original exfoliated graphite is indicated by the presence of a pre-edge signal at 284.2 eV. PMID:23016137

Hitchock, Adam P; Ke, Xiaoxing; Van Tendeloo, Gustaaf; Ewels, Chris P; Guttmann, Peter

2012-01-01

415

Study of hard disk and slider surfaces using X-ray photoemission electron microscopy and near-edge X-ray absorption fine structure spectroscopy  

SciTech Connect

X-ray Photo Emission Electron Microscopy (X-PEEM) and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy were applied to study the properties of amorphous hard carbon overcoats on disks and sliders, and the properties of the lubricant. The modification of lubricants after performing thermal desorption studies was measured by NEXAFS, and the results are compared to the thermal desorption data. The study of lubricant degradation in wear tracks is described. Sliders were investigated before and after wear test, and the modification of the slider coating as well as the transfer of lubricant to the slider was studied. The studies show that the lubricant is altered chemically during the wear. Fluorine is removed and carboxyl groups are formed.

Anders, S.; Stammler, T. [Lawrence Berkeley National lab., CA (United States). Advanced Light Source Div.; Bhatia, C.S. [SSD/IBM, San Jose, CA (United States); Stoehr, J. [IBM Research Div., San Jose, CA (United States). Almaden Research Center; Fong, W.; Chen, C.Y.; Bogy, D.B. [Univ. of California, Berkeley, CA (United States)

1998-04-01

416

A single-shot transmissive spectrometer for hard x-ray free electron lasers  

SciTech Connect

We report hard x-ray single-shot spectral measurements of the Linac Coherent Light Source. The spectrometer is based on a 10 {mu}m thick cylindrically bent Si single crystal operating in the symmetric Bragg geometry to provide dispersion and high transmission simultaneously. It covers a spectral range >1% using the Si(111) reflection. Using the Si(333) reflection, it reaches a resolving power of better than 42 000 and transmits >83% of the incident flux at 8.3 keV. The high resolution enabled the observation of individual spectral spikes characteristic of a self-amplified spontaneous emission x-ray free electron laser source. Potential applications of the device are discussed.

Zhu Diling; Cammarata, Marco; Feldkamp, Jan M.; Fritz, David M.; Hastings, Jerome B.; Lee, Sooheyong; Lemke, Henrik T.; Robert, Aymeric; Turner, James L.; Feng Yiping [Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States)

2012-07-16

417

Sensing the wavefront of x-ray free-electron lasers using aerosol spheres.  

PubMed

Characterizing intense, focused x-ray free electron laser (FEL) pulses is crucial for their use in diffractive imaging. We describe how the distribution of average phase tilts and intensities on hard x-ray pulses with peak intensities of 10(21) W/m(2) can be retrieved from an ensemble of diffraction patterns produced by 70 nm-radius polystyrene spheres, in a manner that mimics wavefront sensors. Besides showing that an adaptive geometric correction may be necessary for diffraction data from randomly injected sample sources, our paper demonstrates the possibility of collecting statistics on structured pulses using only the diffraction patterns they generate and highlights the imperative to study its impact on single-particle diffractive imaging. PMID:23736456

Loh, N Duane; Starodub, Dmitri; Lomb, Lukas; Hampton, Christina Y; Martin, Andrew V; Sierra, Raymond G; Barty, Anton; Aquila, Andrew; Schulz, Joachim; Steinbrener, Jan; Shoeman, Robert L; Kassemeyer, Stephan; Bostedt, Christoph; Bozek, John; Epp, Sascha W; Erk, Benjamin; Hartmann, Robert; Rolles, Daniel; Rudenko, Artem; Rudek, Benedikt; Foucar, Lutz; Kimmel, Nils; Weidenspointner, Georg; Hauser, Guenter; Holl, Peter; Pedersoli, Emanuele; Liang, Mengning; Hunter, Mark S; Gumprecht, Lars; Coppola, Nicola; Wunderer, Cornelia; Graafsma, Heinz; Maia, Filipe R N C; Ekeberg, Tomas; Hantke, Max; Fleckenstein, Holger; Hirsemann, Helmut; Nass, Karol; White, Thomas A; Tobias, Herbert J; Farquar, George R; Benner, W Henry; Hau-Riege, Stefan; Reich, Christian; Hartmann, Andreas; Soltau, Heike; Marchesini, Stefano; Bajt, Sasa; Barthelmess, Miriam; Strueder, Lothar; Ullrich, Joachim; Bucksbaum, Philip; Frank, Matthias; Schlichting, Ilme; Chapman, Henry N; Bogan, Michael J

2013-05-20

418

Time-resolved magnetic domain imaging by x-ray photoemission electron microscopy  

NASA Astrophysics Data System (ADS)

X-ray photoemission electron microscopy (X-PEEM) is a powerful imaging technique that can be used to perform element selective magnetic domain imaging on heterogeneous samples with different magnetic layers, like spin valves and tunnel junctions. We have performed nanosecond time-resolved X-PEEM measurements, on the permalloy layer of a Ni80Fe20 (5 nm)/Cu (10 nm)/Co (5 nm) trilayer deposited on Si(111). We used the pump-probe mode, synchronizing a magnetic pulse from a microcoil with the x-ray photon bunches delivered by the BESSY synchrotron in single bunch mode. Images could be acquired during and after the 20 ns long and 80 Oe high field pulses. The nucleation and subsequent growth of reversed domains in the permalloy could be observed, demonstrating the feasibility of element selective and time-resolved domain imaging using X-PEEM.

Vogel, J.; Kuch, W.; Bonfim, M.; Camarero, J.; Pennec, Y.; Offi, F.; Fukumoto, K.; Kirschner, J.; Fontaine, A.; Pizzini, S.

2003-04-01

419

New spectral classification technique for X-ray sources: quantile analysis  

E-print Network

We present a new technique called "quantile analysis" to classify spectral properties of X-ray sources with limited statistics. The quantile analysis is superior to the conventional approaches such as X-ray hardness ratio or X-ray color analysis to study relatively faint sources or to investigate a certain phase or state of a source in detail, where poor statistics does not allow spectral fitting using a model. Instead of working with predetermined energy bands, we determine the energy values that divide the detected photons into predetermined fractions of the total counts such as median (50%), tercile (33% & 67%), and quartile (25% & 75%). We use these quantiles as an indicator of the X-ray hardness or color of the source. We show that the median is an improved substitute for the conventional X-ray hardness ratio. The median and other quantiles form a phase space, similar to the conventional X-ray color-color diagrams. The quantile-based phase space is more evenly sensitive over various spectral shapes than the conventional color-color diagrams, and it is naturally arranged to properly represent the statistical similarity of various spectral shapes. We demonstrate the new technique in the 0.3-8 keV energy range using Chandra ACIS-S detector response function and a typical aperture photometry involving background subtraction. The technique can be applied in any energy band, provided the energy distribution of photons can be obtained.

Jaesub Hong; Eric M. Schlegel; Jonathan E. Grindlay

2004-06-21

420

Polychromatic excitation improves detection limits in total reflection X-ray fluorescence analysis compared with monochromatic excitation.  

PubMed

Detection limits obtained by a portable total reflection X-ray fluorescence (TXRF) spectrometer with or without a monochromator are compared. A 1 W X-ray tube (tube voltage: 20 kV) is used in this spectrometer. Polychromatic excitation improves the detection limits in TXRF analysis with the low power X-ray tube compared with monochromatic excitation. A detection limit of 26 pg is achieved for Co when using the weak polychromatic X-rays. PMID:20535410

Kunimura, Shinsuke; Kawai, Jun

2010-08-01