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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 analysis and mapping by wavelength dispersive X-ray spectroscopy in an electron microscope  

Microsoft Academic Search

A compact and easy-to-use wavelength dispersive X-ray spectrometer using a multi-capillary X-ray lens attached to a scanning (transmission) electron microscope has been tested for thin-film analysis. B–K spectra from thin-film boron compounds (B4C, h-BN, and B2O3) samples showed prominent peak shifts and detailed structural differences. Mapping images of a thin W\\/Si double-layer sample resolved each element clearly. Additionally, a thin

Miyoko Tanaka; Masaki Takeguchi; Kazuo Furuya

2008-01-01

3

X-ray diffraction-based electronic structure calculations and experimental x-ray analysis for medical and materials applications  

Microsoft Academic Search

This thesis includes x-ray experiments for medical and materials applications and the use of x-ray diffraction data in a first-principles study of electronic structures and hyperfine properties of chemical and biological systems. Polycapillary focusing lenses were used to collect divergent x rays emitted from conventional x-ray tubes and redirect them to form an intense focused beam. These lenses are routinely

Dip Narayan Mahato

2009-01-01

4

X-ray diffraction-based electronic structure calculations and experimental x-ray analysis for medical and materials applications  

NASA Astrophysics Data System (ADS)

This thesis includes x-ray experiments for medical and materials applications and the use of x-ray diffraction data in a first-principles study of electronic structures and hyperfine properties of chemical and biological systems. Polycapillary focusing lenses were used to collect divergent x rays emitted from conventional x-ray tubes and redirect them to form an intense focused beam. These lenses are routinely used in microbeam x-ray fluorescence analysis. In this thesis, their potential application to powder diffraction and focused beam orthovoltage cancer therapy has been investigated. In conventional x-ray therapy, very high energy (˜ MeV) beams are used, partly to reduce the skin dose. For any divergent beam, the dose is necessarily highest at the entry point, and decays exponentially into the tissue. To reduce the skin dose, high energy beams, which have long absorption lengths, are employed, and rotated about the patient to enter from different angles. This necessitates large expensive specialized equipment. A focused beam could concentrate the dose within the patient. Since this is inherently skin dose sparing, lower energy photons could be employed. A primary concern in applying focused beams to therapy is whether the focus would be maintained despite Compton scattering within the tissue. To investigate this, transmission and focal spot sizes as a function of photon energy of two polycapillary focusing lenses were measured. The effects of tissue-equivalent phantoms of different thicknesses on the focal spot size were studied. Scatter fraction and depth dose were calculated. For powder diffraction, the polycapillary optics provide clean Gaussian peaks, which result in angular resolution that is much smaller than the peak width due to the beam convergence. Powder diffraction (also called coherent scatter) without optics can also be used to distinguish between tissue types that, because they have different nanoscale structures, scatter at different angles. Measurements were performed on the development of coherent scatter imaging to provide tissue type information in mammography. Atomic coordinates from x-ray diffraction data were used to study the nuclear quadrupole interactions and nature of molecular binding in DNA/RNA nucleobases and molecular solid BF3 systems.

Mahato, Dip Narayan

5

Calcium measurements with electron probe X-ray and electron energy loss analysis  

Microsoft Academic Search

This paper presents a broad survey of the rationale for electron probe X-ray microanalysis (EPXMA) and the various methods for obtaining qualitative and quantitative information on the distribution and amount of elements, particularly calcium, in cryopreserved cells and tissues. Essential in an introductory consideration of microanalysis in biological cryosections is the physical basis for the instrumentation, fundamentals of X-ray spectrometry,

A. LeFurgey; P. Ingram

1990-01-01

6

Electron probe X-ray analysis of an intraocular foreign body.  

PubMed

We describe a simple and rapid method of electron probe x-ray analysis on a foreign body removed from the eye. We demonstrated the presence of copper in an intraocular foreign body which has originated from a blank 0.22 calibre cartridge. Sodium, potassium, calcium, phosphorus, sulpher and chlorine were also detected. It seems likely that these elements were derived from the biological milieu in which the intraocular foreign body had rested for some 2 years and 9 months. PMID:922576

Chisholm, I A; Lalonde, J M; Ghadially, F N

1977-10-01

7

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

8

Density Gradients for Isolation of Mononuclear Blood Cells for Magnesium Analysis by Electron Probe X-Ray Microanalysis.  

National Technical Information Service (NTIS)

Magnesium in peripheral mononuclear blood cells (MBC) may be a useful indicator of intracellular Mg status. We present a mononuclear blood cell (MBC) isolation method for magnesium analysis by electron probe X-ray microanalysis. We compare the inorganic e...

G. R. Hook J. M. Hosseini R. J. Elin

1988-01-01

9

Electron Population Analysis by Full-Potential X-Ray Absorption Simulations  

NASA Astrophysics Data System (ADS)

We present the first successful attempt at calculating cluster full-potential x-ray absorption near-edge structure (XANES) spectra, based on the finite difference method. By fitting XANES simulations onto experimental spectra we are able to perform electron population analysis. The method is tested in the case of Ti K-edge absorption spectrum in TiO2, where the amount of charge transfer between Ti and O atoms and of the screening charge on the photoabsorber is obtained taking into account both dipolar and quadrupolar transitions.

Joly, Yves; Cabaret, Delphine; Renevier, Hubert; Natoli, Calogero R.

1999-03-01

10

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

11

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

12

Quantitative energy dispersive X-ray analysis of submicrometric particles using a scanning electron microscope.  

PubMed

The quantitative scanning electron microscope-energy dispersive X-ray (SEM-EDX) analysis of a horneblende and two augite prismatic samples reduced to submicrometric particles was performed, and error due to the particle effects ("absent mass" and the "reduced absorption" effect) was minimized. Correction factors as a function of fragment size were obtained for O, Na, Mg, Si, Ca, and Fe. In addition, the influence of chemical composition of the samples used as standards (the matrix effect) on correction factors was evaluated. The results indicate that the absent mass effect is dominant for all elements except for the light elements O and Na, for which the reduced absorption effect is dominant. No significant matrix effect has been observed. By using corrected SEM-EDX data, the error on quantification of the element concentration has been estimated to be 3% relative for light elements and below 2% relative for heavy elements (notably, about 1% relative for Fe). PMID:21892993

Paoletti, Luigi; Bruni, Biagio M; Gianfagna, Antonio; Mazziotti-Tagliani, Simona; Pacella, Alessandro

2011-09-06

13

NIST data resources for surface analysis by X-ray photoelectron spectroscopy and Auger electron spectroscopy  

Microsoft Academic Search

A description is given of data resources that are available from the National Institute of Standards and Technology (NIST) for X-ray photoelectron spectroscopy (XPS) and Auger-electron spectroscopy. NIST currently has three databases available: an XPS Database, an Electron Elastic-Scattering Cross-Section Database, and an Electron Inelastic-Mean-Free-Path Database. NIST also offers Standard Test Data (STD) for XPS, a set of simulated XPS

C. J. Powell; A. Jablonski; A. Naumkin; A. Kraut-Vass; J. M. Conny; J. R. Rumble

2001-01-01

14

Spectroscopic Analysis of Electron Beam Diodes for Flash X-ray Radiography at Sandia National Laboratories*  

NASA Astrophysics Data System (ADS)

Experiments were performed on RITS-3, a Marx driven, three stage IVA (5.5MV, 120kA), and are continuing on RITS-6, a six stage IVA (10MV, 120kA), to study the role of plasma formation and propagation on electron beam focusing for flash x-ray radiography. It is believed that plasmas formed on electrodes or by interactions with background gases limit e-beam focusing and stability and cause pulse shortening of the diode. These are concerns as higher doses (1000 Rad at 1m) from smaller sources (2mm dia.) are required for future radiographic applications. Diagnostics include time and space resolved visible and uv emission spectra using 1 meter Czerny-Turner monochromators equipped with framing and streak cameras. Line and continuum analysis are conducted using a time-dependent CR model. Self-consistent line shape calculations measure Stark, Doppler, and opacity broadening. Electron density and temperature determinations as well as neutral and ion species parameters are obtained. Such data is crucial to the fundamental understanding of electron beam diode behavior and aids in the continued development of these sources. *Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94-AL85000.

Johnston, M. D.; Oliver, B. V.; Hahn, K.; Rovang, D.; Maenchen, J. E.; Droemer, D.; Welch, D. R.; Maron, Y.

2006-10-01

15

Distribution analysis of functional groups in polymers by derivatization-electron probe X-ray microanalysis  

Microsoft Academic Search

A new analytical method referred to as derivatization-electron probe X-ray microanalysis (XMA) has been developed to determine the distribution of 0.1% order functional groups in polymers with ?m level lateral resolution. The fundamental performance of XMA in analyzing derivatized polymers has been investigated. The results showed that the detection limit for the concentration of Br in a brominated epoxy resin

M Sugiura; A Murase; T Mitsuoka

2001-01-01

16

Distribution analysis of epoxy groups in polymers by derivatization-electron probe X-ray microanalysis.  

PubMed

An analytical method, referred to as "derivatization-electron probe X-ray micro-analysis (XMA)", has been developed to determine the distribution of a small amount of the functional groups in a polymer. The suitable conditions for the derivatization reaction with epoxy groups, which contribute to the hardening reactions of polymers, were investigated. It was found that epoxy groups in polymers were derivatized selectively using gas-phase esterification with hydrochloric acid (HCI). The most suitable amount of HCl in a 50 ml vial was 300 microl. After setting a sample in the vessel without directly contacting the reagent, by reacting the reagent and the sample at 25 degrees C for 1 h, the highest reaction yield and selectivity were obtained. By derivatization-XMA using this reaction condition, the measurement of the distribution of epoxy groups in the polymer became feasible. Actual applications to a depth analysis of epoxy groups in the hardened acrylic coating and epoxy resin proved that this method is useful for the characterization of polymers and for the study of the hardening reaction of polymers. PMID:11990569

Sugiura, M; Fukumoto, K; Murase, A; Ueda, K

2001-04-01

17

X-ray and scanning electron microscopic analysis of the structural composition of tear ferns.  

PubMed

Dried tears from keratoconjunctivitis sicca eyes fail to exhibit the fern-like crystallization patterns observed with tears from eyes with normal tear function. To test our hypothesis that the extent of ferning depends on the ratio of salts to protein and mucin in the tear sample, dried tears from six normal subjects were subjected to scanning electron microscopy (SEM) and X-ray analyses. X-ray diffraction identified sodium chloride and potassium chloride as the major components of tear fern crystals. X-ray fluorescence detected the elements potassium, chlorine, calcium, and sulfur in the dried tear samples, with sulfur indicating the presence of protein and/or mucin. As well as confirming the presence of cubic fern nuclei, SEM revealed two kinds of material, having crystalline and globular appearances, that are hypothesized to be composed of salts and protein/mucin, respectively. Globular material appeared to block extension of crystal fern arms or to coat crystalline material, but did not crystallize. These findings suggest that tear fern crystals are composed of sodium and potassium chloride, with proteinaceous material controlling crystallization indirectly by coating crystal faces and blocking fern extension. This structural composition is consistent with the hypothesis that the ratio of salt to macromolecular species is an important determinant of tear ferning. PMID:8131408

Golding, T R; Baker, A T; Rechberger, J; Brennan, N A

1994-01-01

18

Solid-State Energy-Dispersion Spectrometer for Electron-Microprobe X-ray Analysis  

Microsoft Academic Search

Improved lithium-drifted silicon solid-state detectors allow detection and energy dispersion of x-rays of about 3 to 30 kiloelectron volts in the electronmicroprobe x-ray analyzer. Energy resolution is sufficient to separate peaks of characteristic x-rays of elements adjacent in the periodic system at atomic number 20 and higher. The detected x-ray spectrum emitted from an unknown sample can be recorded with

Ray Fitzgerald; Klaus Keil; Kurt F. J. Heinrich

1968-01-01

19

X-ray free-electron lasers  

NASA Astrophysics Data System (ADS)

With intensities 108-1010 times greater than other laboratory sources, X-ray free-electron lasers are currently opening up new frontiers across many areas of science. In this Review we describe how these unconventional lasers work, discuss the range of new sources being developed worldwide, and consider how such X-ray sources may develop over the coming years.

McNeil, Brian W. J.; Thompson, Neil R.

2010-12-01

20

X-ray Free-electron Lasers  

Microsoft Academic Search

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

Claudio Pellegrini; Claudio

2009-01-01

21

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

22

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

23

Probing Heterogeneous Chemistry of Individual Atmospheric Particles Using Scanning Electron Microscopy and Energy-Dispersive X-ray Analysis  

SciTech Connect

In this paper, we demonstrate the utility of single-particle analysis to investigate the chemistry of isolated, individual particles of atmospheric relevance such as NaCl, sea salt, CaCO3, and SiO2. A variety of state-of-th-art scanning electron microscopy techniques, including environmental scanning electon microscopy and computer-controlled scanning electron microscopy/energy-dispersive X-ray analysis, were utilized for monitoring and quantifying phase transitions of individual particles, morphology, and compositional changes of individual particles as they react with nitric acid.

Krueger, Brenda J.; Grassian, Vicki H.; Iedema, Martin J.; Cowin, James P.; Laskin, Alexander

2003-10-01

24

Single shot speckle and coherence analysis of the hard X-ray free electron laser LCLS.  

PubMed

The single shot based coherence properties of hard x-ray pulses from the Linac Coherent Light Source (LCLS) were measured by analyzing coherent diffraction patterns from nano-particles and gold nanopowder. The intensity histogram of the small angle x-ray scattering ring from nano-particles reveals the fully transversely coherent nature of the LCLS beam with a number of transverse mode ?Ms? = 1.1. On the other hand, the speckle contrasts measured at a large wavevector yields information about the longitudinal coherence of the LCLS radiation after a silicon (111) monochromator. The quantitative agreement between our data and the simulation confirms a mean coherence time of 2.2 fs and a x-ray pulse duration of 29 fs. Finally the observed reduction of the speckle contrast generated by x-rays with pulse duration longer than 30 fs indicates ultrafast dynamics taking place at an atomic length scale prior to the permanent sample damage. PMID:24150309

Lee, Sooheyong; Roseker, W; Gutt, C; Fischer, B; Conrad, H; Lehmkühler, F; Steinke, I; Zhu, D; Lemke, H; Cammarata, M; Fritz, D M; Wochner, P; Castro-Colin, M; Hruszkewycz, S O; Fuoss, P H; Stephenson, G B; Grübel, G; Robert, A

2013-10-21

25

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

Microsoft Academic Search

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 CO2 plasma. The x-ray spectral and dose measurements

R. Baskaran; T. S. Selvakumaran

2008-01-01

26

Electron Temperature and Zsub(Eff) Measurements in Hot Plasmas by Soft X-Ray Analysis.  

National Technical Information Service (NTIS)

A hot plasma can be analyzed by means of the soft X-ray fluxes using various absorbers. In the first part, the method of calculation of the flux as a function of Tsub(e), Zsub(eff), nsub(e) and their profiles is given. The problem of relativistic correcti...

1977-01-01

27

[Fragment-based screening by X-ray structure analysis].  

PubMed

The first step of FBDD is fragment-based screening (FBS). There are various analytical methods used to perform FBS: NMR, X-rays, SPR, etc. The advantage of X-ray structure analysis in FBS is that it can cope with relatively large structural changes upon the binding of a fragment and unexpected events such as multiple binding. The first thing needed to perform FBS by X-rays is a fragment library. The library currently employed at our laboratory was designed especially for X-ray structure analysis and consists of 384 compounds. This library was built based on Ro3 and special attention was given to eliminating ambiguity when interpreting electron density. FBS by X-rays requires more than 100 times more data collection and structure analysis. Recent development of critical technologies dramatically reduced the time required for X-ray structure analysis. Additionally, development of software and the incorporation of an industrial robot to a laboratory system has enabled us to construct a fully automated structure analysis system. However, there still are some limitations to X-ray structure analysis. It demands hundreds of high quality crystals and those crystals must not only survive soaking of compounds dissolved in DMSO but also be resistant to X-ray damage. In this article, a practical example of FBS by X-rays will be presented using HSP90 along with facts on the limitations of X-rays. PMID:20190518

Yamano, Akihito

2010-03-01

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

Convergent x-ray monochromator for molecular microprobe analysis  

DOEpatents

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.

1990-12-31

31

Convergent x-ray monochromator for molecular microprobe analysis  

DOEpatents

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

Development of a multifunctional surface analysis system based on a nanometer scale scanning electron beam: Combination of ultrahigh vacuum-scanning electron microscopy, scanning reflection electron microscopy, Auger electron spectroscopy, and x-ray photoelectron spectroscopy  

Microsoft Academic Search

We have developed a multifunctional surface analysis system based on a scanning electron beam for nanofabrication and characterization of surface reactions for fabrication processes. The system performs scanning electron microscopy (SEM), scanning reflection electron microscopy (SREM), Auger electron spectroscopy (AES), and x-ray photoelectron spectroscopy. Nanometer scale resolution is obtained for ultrahigh vacuum (UHV)-SEM while the mechanical pumping instruments are operated.

Heiji Watanabe; Masakazu Ichikawa

1996-01-01

33

Generation of Parametric X-rays by using Electron Accelerator  

SciTech Connect

Generation of a parametric X-rays using a Silicon crystal plane and a 150 MeV electron beam generated by a Microtron accelerator were performed. 10 keV class X-rays have been detected at the generation condition of the X-rays. We consider the X-rays flux is approx1 photons/(electrons sr). Also high-energy X-rays generated by harmonics of parametric process were observed.

Hayashi, Yukio; Kando, Masaki; Kotaki, Hideyuki; Kawase, Keigo; Homma, Takayuki [Advanced Photon Research Center, Japan Atomic Energy Agency, 8-1 Umemidai, Kizugawa-shi, Kyoto 619-0215 (Japan); Bulanov, Sergei V. [Advanced Photon Research Center, Japan Atomic Energy Agency, 8-1 Umemidai, Kizugawa-shi, Kyoto 619-0215 (Japan); Moscow Institute of Physics and Technology, Institutskij pereulok 9, Dolgoprudny, 141700 Moscow region (Russian Federation); A. M. Prokhorov Institute of General Physics of the Russian Academy of Sciences, Vavilov Street 38, 119991 Moscow (Russian Federation)

2009-07-25

34

Proton induced x ray emission analysis  

Microsoft Academic Search

A solid mathematical basis is established for the use of thick target Proton Induced X ray Emission (PIXE) analysis to determine the trace element concentrations in solid samples. With the advent of high resolution Si(Li) detectors there was a revival of interest in the use of characteristic x ray induced by high energy particle beams. It was shown that it

Eric Clayton

1988-01-01

35

X-ray Analysis of Unknown Minerals  

NSDL National Science Digital Library

In this exercise, students use X-ray analysis to identify unknown minerals. They are given two samples to grind up and X-ray, using Jade to identify them. Once the minerals are identified, students make a spreadsheet and do a series of calculations.

Perkins, Dexter

36

Analysis of Individual Environmental Particles Using Modern Methods of Electron Microscopy and X-Ray Microanalysis  

SciTech Connect

Understanding the composition of particles in the atmosphere is critical because of their health effects and their direct and indirect effects on radiative forcing, and hence on climate. In this manuscript, we demonstrate the utility of single particle off-line analysis to investigate the chemistry of individual atmospheric particles using modern, state-of-the-art electron microscopy and time-of-flight secondary ionization mass spectrometry techniques. We show that these methods provide specific, detailed data on particle composition, chemistry, morphology, phase and internal structure. This information is crucial for evaluating hygroscopic properties of aerosols, understanding aerosol aging and reactivity, and correlating the characteristics of aerosols with their optical properties. The manuscript presents a number of analytical advances in methods of electron probe particle analysis along with a brief review of a number of the research projects carried out in the authors’ laboratory on the chemical characterization of environmental particles. The obtained data offers a rich set of qualitative and quantitative information on the particle chemistry, composition and the mechanisms of gas-particle interactions which are of high importance to atmospheric processes involving particulate matter and air pollution.

Laskin, Alexander; Cowin, James P.; Iedema, Martin J.

2006-02-01

37

Scanning Transmission Electron microscope Studies of Deep-Frozen Unfixed Muscle Correlated with Spatial Localization of Intracellular Elements by Fluorescent X-Ray Analysis  

PubMed Central

Thin sections of deep-frozen unfixed muscle were studied in a scanning electron microscope modified for transmission imaging and equipped with a “cryostage” for vacuum compatibility of hydrated tissue. With an energy-dispersive x-ray analysis system, intracellular atomic species in the scan beam path were identified by their fluorescent x-rays and spatially localized in correlation with the electron optical image of the microstructure. Marked differences are noted between the ultrastructure of deep-frozen hydrated muscle and that of fixed dehydrated muscle. In frozen muscle, myofibrils appear to be composed of previously undescribed longitudinal structures between 400-1000 Å wide (“macromyofilaments”). The usual myofilaments, mitochondria, and sarcoplasmic reticulum were not seen unless the tissue was “fixed” before examination. Fluorescent x-ray analysis of the spatial location of constituent elements clearly identified all elements heavier than Na. Intracellular Cl was relatively higher than expected. Images

Bacaner, Marvin; Broadhurst, John; Hutchinson, Thomas; Lilley, John

1973-01-01

38

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

NASA Astrophysics Data System (ADS)

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

1991-05-01

39

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

NASA Astrophysics Data System (ADS)

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 CO2 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 <=10-5 Torr, whereas the UV emission is found to be negligible for the gas pressures <10-5 Torr and it starts increasing in the pressure range between 10-5 and 10-3 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.

2008-02-01

40

ANALYSIS OF PASSIVATED SURFACES FOR MASS SPECTROMETER INLET SYSTEMS BY AUGER ELECTRON AND X-RAY PHOTOELECTRON SPECTROSCOPY  

SciTech Connect

Stainless steel coupons approximately 0.5' in diameter and 0.125' thick were passivated with five different surface treatments and an untreated coupon was left as a control. These surface treatments are being explored for use in tritium storage containers. These coupons were made to allow surface analysis of the surface treatments using well-know surface analysis techniques. Depth profiles using Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were performed on these coupons to characterize the surface and near surface regions. Scanning electron microscope (SEM) images were collected as well. All of the surface treatments studied here appear to change the surface morphology dramatically, as evidenced by lack of tool marks on the treated samples. In terms of the passivation treatment, Vendors A-D appeared to have oxide layers that were very similar in thickness to each other (0.7-0.9 nm thick) as well as the untreated samples (the untreated sample oxide layers appeared to be somewhat larger). Vendor E's silicon coating appears to be on the order of 200 nm thick.

Ajo, H.; Clark, E.

2010-09-01

41

X-ray Analysis of Sand  

NSDL National Science Digital Library

This is an x-ray diffraction analysis of six sand samples and comparison with hand specimens. Students look at each of the six samples under the binocular microscope and note such useful properties as number of minerals, cleavage/fracture, color, shape, grain size, roundness, and degree of sorting. Then they grind up small amounts of each sample and mount them on glass slides for X-ray. Students write all sample descriptions and X-ray analysis results in their lab notebook. Then they identify the minerals in each sample, determine where they are from, and write a report summarizing all results.

Perkins, Dexter

42

Evaluation of the acetate buffer attack of a sequential extraction scheme for marine particulate metal speciation studies by scanning electron microscopy with energy dispersive X-ray analysis  

Microsoft Academic Search

Scanning electron microscopy, with energy dispersive X-ray analysis (SEM-EDX), has been used to evaluate and possibly optimize, the first step (acetate buffer attack for exchangeable and carbonatic fractions) of a sequential selective extraction scheme. The extraction has been performed on two different particulates, a certified reference plankton and a real marine suspended particulate, using an increased acetate concentration and various

F Baffi; C Ianni; M Ravera; F Soggia; E Magi

1998-01-01

43

Forensic analysis of soil and sediment traces by scanning electron microscopy and energy-dispersive X-ray analysis: An experimental investigation  

Microsoft Academic Search

This paper reports the results of a series of experiments carried out to determine the precision of soil trace comparisons based on elemental peak height ratios determined by energy-dispersive X-ray analysis (EDXRA) in a variable pressure scanning electron microscope (VP-SEM). Experiments were conducted on ‘bulk’ soil aggregates, ground powders prepared from the <150?m soil fractions and on smears of both

Kenneth Pye; Debra Croft

2007-01-01

44

Attosecond X-ray free electron laser  

NASA Astrophysics Data System (ADS)

For a real, meaningful pump-probe experiment with attosecond temporal resolution, an isolated attosecond pulse is in demand. In this vein we report the generation of an isolated ~ 148 attosecond pulse duration radiation pulse at 0.1 angstrom wavelength using current enhanced self-amplified spontaneous emission free electron laser. We consider the 10-GeV PAL-XFEL e-beam for enhanced self-amplified spontaneous emission (ESASE) scheme. In ESASE, X-ray SASE FEL is combined with a femtosecond laser system. An 800 nm wavelength, 5 fs FWHM carrier envelope phase stabilized laser was employed in ESASE scheme.

Kumar, S.; Kang, H. S.; Kim, D. E.

2013-03-01

45

New analysis method for CCD X-ray data  

Microsoft Academic Search

The analysis method developed for kaonic nitrogen X-ray data obtained at the DA?NE electron–positron collider of Frascati National Laboratories using Charge-Coupled Devices (CCDs) in the DEAR experimental setup is described. Background events could be highly rejected by this analysis procedure. Three sequential X-ray lines from kaonic nitrogen transitions, showing good energy resolution, could be clearly identified, and the yields measured

T. Ishiwatari; G. Beer; A. M. Bragadireanu; M. Cargnelli; J.-P. Egger; H. Fuhrmann; C. Guaraldo; M. Iliescu; K. Itahashi; M. Iwasaki; P. Kienle; B. Lauss; V. Lucherini; L. Ludhova; J. Marton; F. Mulhauser; T. Ponta; L. A. Schaller; D. L. Sirghi; F. Sirghi; P. Strasser; J. Zmeskal

2006-01-01

46

Innovations in X-ray-induced electron emission spectroscopy (XIEES)  

SciTech Connect

Currently, a pressing need has arisen for controlling the local atomic and electron structure of materials irrespective of their aggregate state. Efficient approaches to the studies of short-range order are based on phenomena accompanied by interference of secondary electrons excited by primary X-ray radiation. The set of such approaches are commonly referred to as the X-ray absorption fine structure (XAFS) methods. In reality, the XAFS methods are based on the use of synchrotron radiation and applied to structural studies in two modes of measurements, transmission analysis and recording of secondary effects. Only two such effects-specifically, the X-ray fluorescence an d X-ray-induced electron emission effect-are commonly discussed. Access to synchrotron accelerators is problematic for most researchers, so a demand is created for designing laboratory systems that make direct access possible. Since the power of laboratory systems is much lower than that of synchrotrons, it is essential to use much more efficient detectors of secondary electrons. In addition, it is of interest to analyze energy characteristics with a high spatial resolution. Channel multipliers and multichannel boards are incapable of providing such a possibility. For this reason, an improved electron detector has been developed to analyze the photoemission effect in an accelerating field.

Pogrebitsky, K. Ju., E-mail: mischar@mail.ioffe.ru; Sharkov, M. D. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)

2010-06-15

47

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

48

Low Power X-Ray Tube for Use in Energy Dispersive X-Ray Fluorescence Analysis.  

National Technical Information Service (NTIS)

A low power X-ray tube with thin molybdenum transmission target for use in energy dispersive X-ray fluorescence (ENDXRF) element analysis has been indigenously built, along with its power supply. The X-ray tube has been in operation since August 1979, and...

S. K. Kataria R. Govil M. Lal

1980-01-01

49

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

50

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

PubMed

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 (~?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?. Exemplary soft x-ray spectroscopy studies and results of selective x-ray fluorescence analysis are presented. PMID:23277967

Sokaras, D; Zarkadas, Ch; Fliegauf, R; Beckhoff, B; Karydas, A G

2012-12-01

51

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

52

Fundamental characteristics of hybrid X-ray focusing optics for micro X-ray fluorescence analysis  

NASA Astrophysics Data System (ADS)

We developed a hybrid X-ray focusing optics, which consisted of a polycapillary X-ray lens (PCXL) and a tungsten conical pinhole (WCP) for micro X-ray fluorescence (?-XRF) analysis. A single PCXL produced an X-ray micro beam with a spot size of 12 ?m. We developed a WCP by using a laser-ablation technique with an input diameter of 39 ?m, an output diameter of 2.5 ?m, and a thickness of 0.5 mm in a conical shape. This hybrid X-ray optics gave a small spot size of 2.8 ?m with a small divergent angle of 12 mrad.

Komatani, Shintaro; Nakamachi, Kazuo; Nakano, Kazuhiko; Ohzawa, Sumito; Uchihara, Hiroshi; Bando, Atsushi; Tsuji, Kouichi

2013-08-01

53

X-ray Astronomy and the Analysis of X-ray Data  

NASA Astrophysics Data System (ADS)

The Chandra X-ray Observatory, launched in 1999, continues to return spectacular scientific results thanks to its combination of high spatial and spectral resolution. I will discuss a selection of these results, and draw attention to the specific data analysis challenges posed by X-ray observatories in general, leading to the identification of the spatial distribution of elements in supernova remnants, the discovery of X-ray jets in galactic and extragalactic objects, the resolution of the X-ray background into faint sources, and the analysis of X-ray spectra of individual sources in external galaxies. The X-ray event list paradigm provides a compact representation of a sparse multidimensional dataset, supporting time- and energy-resolved hundred-megapixel images. In contrast to the case of HST and ground-based telescopes, the pointing of X-ray telescopes, while known accurately after the fact, is not kept constant during the observation. Sharp X-ray images are reconstructed from a dithered picture using star tracker data. The imaging point spread function and spectral energy response vary greatly across the field of view and must be carefully calibrated. For X-ray CCD data, the line spread function is broad and multi-peaked, driving us to forward-fitting solutions. For high resolution grating data, order separation is a challenge. Finally, in all X-ray data the low count rate and the ubiquitous cosmic X-ray background require careful statistical attention. Despite these complexities, the standard data analysis packages like CIAO, HEASOFT and SAS are mature enough to allow non-specialist users to reliably extract high quality science from X-ray observations.

McDowell, J. C.

2006-07-01

54

X-ray and electron microscopy of actinide materials  

Microsoft Academic Search

Actinide materials demonstrate a wide variety of interesting physical properties in both bulk and nanoscale form. To better understand these materials, a broad array of microscopy techniques have been employed, including transmission electron microscopy (TEM), electron energy-loss spectroscopy (EELS), energy dispersive X-ray spectroscopy (EDXS), high-angle annular dark-field imaging (HAADF), scanning electron microscopy (SEM), wavelength dispersive X-ray spectroscopy (WDXS), electron back

Kevin T. Moore

2010-01-01

55

X-ray Astronomy and the Analysis of X-ray Data  

Microsoft Academic Search

The Chandra X-ray Observatory, launched in 1999, continues to return spectacular scientific results thanks to its combination of high spatial and spectral resolution. I will discuss a selection of these results, and draw attention to the specific data analysis challenges posed by X-ray observatories in general, leading to the identification of the spatial distribution of elements in supernova remnants, the

J. C. McDowell

2006-01-01

56

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

57

Micro and imaging x-ray analysis by using polycapillary x-ray optics  

NASA Astrophysics Data System (ADS)

We have studied the micro x-ray fluorescence (XRF) and 2D- or 3D-XRF analysis in the laboratory by using polycapillary optics. A confocal 3D micro-XRF instrument was applied for solid/liquid interface analysis. 2D elemental maps of x-ray fluorescence for the solid surface of an Fe plate after Cu was deposited by chemical plating were obtained. The 2D images could be taken in the solution. This result suggests that this 3D micro-XRF method is useful for in-situ monitoring of chemical reactions on solid-liquid interfaces. Furthermore, we have reported a new application of polycapillary x-ray optics. Two independent straight polycapillary optics were arranged between the sample and an x-ray energy dispersive detector. X-ray fluorescence emitted from the sample was collimated by the first capillary, and then it was introduced into the second capillary. By adjusting the angle between two capillary optics, only the x-rays totally reflected on the inner wall of the second capillary could be detected by the x-ray detector. This result suggests that we can use these polycapillary optics for x-ray energy filtering optics.

Tsuji, Kouichi; Nakano, Kazuhiko; Yamaguchi, Makoto; Yonehara, Tasuku

2008-08-01

58

X-ray zone plates fabricated using electron-beam and x-ray lithography  

Microsoft Academic Search

Fresnel zone plate patterns, free of spherical abberation, with diameters of up to 0.63 mm and linewidths as small as 1000 A were fabricated on polyimide-membrane x-ray masks using scanning electron beam lithography Distortion of the electron beam scan raster was reduced to < 2500 A over a 2 mm x 2 mm field by applying deflection corrections, while viewing

D. C. Shaver; D. C. Flanders; N. M. Ceglio; H. I. Smith

1979-01-01

59

Simple Methodology for Obtaining X-Ray Color Images in Scanning Electron Microscopy.  

National Technical Information Service (NTIS)

A simple methodology for obtaining at least 3 elements X-ray images in only one photography is described. The fluorescent X-ray image is obtained from scanning electron microscopy with energy dispersion analysis system. The change of detector analytic cha...

M. M. Veiga L. R. V. Pietroluongo

1985-01-01

60

Introduction to Energy-Dispersive X-Ray Fluorescence Analysis.  

National Technical Information Service (NTIS)

The physical principles of energy dispersive x-ray fluorescence analysis are discussed. A phenomenological description of atomic excitation and the subsequent radiation of x rays on which the physical principles are built, is presented. The atomic shell s...

D. C. Camp

1978-01-01

61

X-ray chemical analysis of YBa2Cu3Ox thin film by total-reflection-angle X-ray spectroscopy  

Microsoft Academic Search

Scanning electron microscopy and total-reflection-angle X-ray spectroscopy (SEM-TRAXS) was applied to X-ray chemical analysis of a 800 Å thick YBa2Cu3Ox (YBCO) film on an MgO substrate. In this method, the emission efficiency of characeti X-rays, excited by the electron beam of a SEM, from elements composing a thin film is drastically enhanced, as compared to that in the conventional SEM-EDX

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

1992-01-01

62

Structural and electron density changes in dense guest-host systems: Analysis of X-ray diffraction data by the Rietveld and Maximum Entropy Methods  

Microsoft Academic Search

When studying the high-pressure structural behavior of crystalline materials, it is highly desirable to determine structural changes accurately, preferably at electron density levels. The Maximum Entropy Method (MEM) has already proven to be a very powerful tool for extracting the most probable charge density distributions directly from X-ray diffraction data. This thesis presents high pressure X-ray diffraction studies on two

Roxana Ioana Flacau

2007-01-01

63

Micro and imaging x-ray analysis by using polycapillary x-ray optics  

Microsoft Academic Search

We have studied the micro x-ray fluorescence (XRF) and 2D- or 3D-XRF analysis in the laboratory by using polycapillary optics. A confocal 3D micro-XRF instrument was applied for solid\\/liquid interface analysis. 2D elemental maps of x-ray fluorescence for the solid surface of an Fe plate after Cu was deposited by chemical plating were obtained. The 2D images could be taken

Kouichi Tsuji; Kazuhiko Nakano; Makoto Yamaguchi; Tasuku Yonehara

2008-01-01

64

Introduction to energy-dispersive x-ray fluorescence analysis  

Microsoft Academic Search

The physical principles of energy dispersive x-ray fluorescence analysis are discussed. A phenomenological description of atomic excitation and the subsequent radiation of x rays on which the physical principles are built, is presented. The atomic shell structure and nomenclature, x-ray nomenclature and energies, x-ray intensities and fluorescence yields, and a brief description of the competing Auger and Coster-Kronig transitions are

1978-01-01

65

Synchrotron x-ray fluorescence and extended x-ray absorption fine structure analysis  

SciTech Connect

The advent of dedicated synchrotron radiation sources has led to a significant increase in activity in many areas of science dealing with the interaction of x-rays with matter. Synchrotron radiation provides intense, linearly polarized, naturally collimated, continuously tunable photon beams, which are used to determine not only the elemental composition of a complex, polyatomic, dilute material but also the chemical form of the elements with improved accuracy. Examples of the application of synchrotron radiation include experiments in synchrotron x-ray fluorescence (SXRF) analysis and extended x-ray absorption fine structure (EXAFS) analysis. New synchrotron radiation x-ray microprobes for elemental analysis in the parts per billion range are under construction at several laboratories. 76 references, 24 figures.

Chen, J.R.; Gordon, B.M.; Hanson, A.L.; Jones, K.W.; Kraner, H.W.; Chao, E.C.T.; Minkin, J.A.

1984-01-01

66

Ultrafast Hard X-Rays from Electron Accelerators  

NASA Astrophysics Data System (ADS)

Modern third-generation synchrotrons are many orders of magnitude brighter than laser-based laboratory sources of x-ray radiation (see figure 1 and reference [8]). Their importance in ultrafast x-ray science has been limited in the past, because the x-ray pulse duration is generally no shorter than the electron bunch lengths in synchrotrons, which are constrained by various technical considerations in electron storage rings to a range of tens of picoseconds or longer [15]. Some important dynamical phenomena can be studied in this sub-nanosecond time range (for example, [11]); however, the fundamental motion of interatomic bonds is in the range of 10's to 100's of femtoseconds. Therefore there is a strong research incentive to find new ways to shorten the pulse duration of x-rays from synchrotron radiation. (See, for example, the recent review [1].)

Bucksbaum, P. H.; Reis, D. A.; Hastings, J.

67

Analysis of the expected AGIPD detector performance parameters for the European X-ray free electron laser  

NASA Astrophysics Data System (ADS)

A review of the parameters of the AGIPD detector planned to be used on the SASE 1 and SASE 2 beamlines of the European XFEL is presented. For both Coherent X-ray Diffraction Imaging (CXDI) and X-ray Photon-Correlation Spectroscopy (XPCS), the required detector noise level and dynamic range are evaluated from signal and background simulations on a per instrument basis. A worst case scenario of accumulated dose is computed in order to evaluate the required detector radiation hardness. Finally, acknowledging a mismatch between pixel size requirement and technological feasibility in the case of XPCS, the possibility to aperture the pixel in order to match the size requirement is presented and discussed.

Potdevin, Guillaume; Graafsma, Heinz

2011-12-01

68

Thomson-Backscattered X Rays From Laser-Accelerated Electrons  

SciTech Connect

We present the first observation of Thomson-backscattered light from laser-accelerated electrons. In a compact, all-optical setup, the ''photon collider,'' a high-intensity laser pulse is focused into a pulsed He gas jet and accelerates electrons to relativistic energies. A counterpropagating laser probe pulse is scattered from these high-energy electrons, and the backscattered x-ray photons are spectrally analyzed. This experiment demonstrates a novel source of directed ultrashort x-ray pulses and additionally allows for time-resolved spectroscopy of the laser acceleration of electrons.

Schwoerer, H.; Liesfeld, B.; Schlenvoigt, H.-P.; Amthor, K.-U.; Sauerbrey, R. [Institut fuer Optik und Quantenelektronik, Friedrich-Schiller-Universitaet, Max-Wien-Platz 1, 07743 Jena (Germany)

2006-01-13

69

Thomson-backscattered x rays from laser-accelerated electrons.  

PubMed

We present the first observation of Thomson-backscattered light from laser-accelerated electrons. In a compact, all-optical setup, the "photon collider," a high-intensity laser pulse is focused into a pulsed He gas jet and accelerates electrons to relativistic energies. A counterpropagating laser probe pulse is scattered from these high-energy electrons, and the backscattered x-ray photons are spectrally analyzed. This experiment demonstrates a novel source of directed ultrashort x-ray pulses and additionally allows for time-resolved spectroscopy of the laser acceleration of electrons. PMID:16486464

Schwoerer, H; Liesfeld, B; Schlenvoigt, H-P; Amthor, K-U; Sauerbrey, R

2006-01-10

70

Flash X-Ray (FXR) Accelerator Optimization Electronic Time-Resolved Measurement of X-Ray Source Size  

SciTech Connect

Lawrence Livermore National Laboratory (LLNL) is currently investigating various approaches to minimize the x-ray source size on the Flash X-Ray (FXR) linear induction accelerator in order to improve x-ray flux and increase resolution for hydrodynamic radiography experiments. In order to effectively gauge improvements to final x-ray source size, a fast, robust, and accurate system for measuring the spot size is required. Timely feedback on x-ray source size allows new and improved accelerator tunes to be deployed and optimized within the limited run-time constraints of a production facility with a busy experimental schedule; in addition, time-resolved measurement capability allows the investigation of not only the time-averaged source size, but also the evolution of the source size, centroid position, and x-ray dose throughout the 70 ns beam pulse. Combined with time-resolved measurements of electron beam parameters such as emittance, energy, and current, key limiting factors can be identified, modeled, and optimized for the best possible spot size. Roll-bar techniques are a widely used method for x-ray source size measurement, and have been the method of choice at FXR for many years. A thick bar of tungsten or other dense metal with a sharp edge is inserted into the path of the x-ray beam so as to heavily attenuate the lower half of the beam, resulting in a half-light, half-dark image as seen downstream of the roll-bar; by measuring the width of the transition from light to dark across the edge of the roll-bar, the source size can be deduced. For many years, film has been the imaging medium of choice for roll-bar measurements thanks to its high resolution, linear response, and excellent contrast ratio. Film measurements, however, are fairly cumbersome and require considerable setup and analysis time; moreover, with the continuing trend towards all-electronic measurement systems, film is becoming increasingly difficult and expensive to procure. Here, we shall discuss an x-ray source size measurement system which utilizes a traditional roll-bar setup combined with a high resolution gated CCD camera, fast-response organic plastic scintillator, and image processing and analysis software, which is executable on a standard PC running which is executable on a standard PC running LabVIEW and Matlab. Analysis time is reduced from several hours to several minutes, while our experimental results demonstrate good agreement with both traditional film-based roll-bar measurements as well as the entirely unrelated technique of x-ray pinhole camera measurements; in addition, our time-resolved measurements show a significant variation in source size throughout the 70 ns beam pulse, a phenomenon which requires further investigation and indicates the possibility of greatly improving final spot size.

Jacob, J; Ong, M; Wargo, P

2005-07-21

71

Inelastic X-ray Scattering Studies of Electronic Excitations  

NASA Astrophysics Data System (ADS)

Inelastic x-ray scattering (IXS) has developed into one of the most powerful momentum-resolved spectroscopies. Especially in the last decade, it has achieved significant progress utilizing brilliant x-rays from third-generation synchrotron radiation facilities. Simultaneously, theoretical efforts have been made to predict or interpret the experimental spectra. One of the scientific fields studied intensively by IXS is strongly correlated electron systems, where the interplay of charge, spin, and orbital degrees of freedom determines their physical properties. IXS can provide a new insight into the electron dynamics of the systems through the observation of charge, spin, and orbital excitations. Focusing on the momentum-resolved electronic excitations in strongly correlated electron systems, we review IXS studies and the present capabilities of IXS for the study of the dynamics of materials. With nonresonant inelastic x-ray scattering (NIXS), one can directly obtain dynamical charge correlation and we discuss its complementary aspects with inelastic neutron scattering. NIXS also has a unique capability of measuring higher multipole transitions, which are usually forbidden in conventional optical absorption. Resonant inelastic x-ray scattering (RIXS) is now established as a valuable tool for measuring charge, spin, and orbital excitations in a momentum-resolved manner. We describe RIXS works on cuprates in detail and show what kind of electronic excitations have been observed. We also discuss RIXS studies on other transition-metal compounds. Finally, we conclude with an outlook on IXS using next-generation x-ray sources.

Ishii, Kenji; Tohyama, Takami; Mizuki, Jun'ichiro

2013-02-01

72

Auger-electron, X-ray and optical emissions  

NASA Astrophysics Data System (ADS)

A system to simultaneously measure Auger-electron, X-ray and optical emissions, induced by 100-400 keV heavy ions from surfaces, has been designed, constructed and tested. The Auger spectrometer is a rotatable, 30°-entrance-angle, parallel-plate electron energy analyzer with a channeltron detector and it has a resolution of 0.29%. The X-ray and optical emissions are measured with a standard Si(Li) PIXE detector and electronics and with a Jarrell-Ash monochrometer, respectively. Preliminary data are presented.

Trbojevic, D.; Treado, P. A.; Lambert, J. M.

1985-05-01

73

Crystallization and preliminary X-ray diffraction analysis of a complex between the electron-transfer partners hexameric Cu-containing nitrite reductase and pseudoazurin.  

PubMed

The complex between Cu-containing nitrite reductase (HdNIR) and its electron-donor protein pseudoazurin (HdPAz) from Hyphomicrobium denitrificans has been crystallized. The crystals were obtained from a mixture of the two proteins using the hanging-drop vapour-diffusion method in the presence of polyethylene glycol (PEG) and 2-methyl-2,4-pentanediol (MPD) as precipitants. SDS-PAGE analysis demonstrated that the crystals contained both proteins. The X-ray diffraction experiment was carried out at SPring-8 and diffraction data were collected to 3.3 A resolution. The crystals were tetragonal (space group P4(1)2(1)2), with unit-cell parameters a = b = 130.39, c = 505.55 A. Preliminary analysis indicated that there was one HdNIR and at least two HdPAz molecules in the asymmetric unit of the crystal. PMID:19193999

Hira, Daisuke; Nojiri, Masaki; Suzuki, Shinnichiro

2009-01-07

74

XPS (x-ray photoelectron spectroscopy), AES (Auger electron spectroscopy), RBS (Rutherford backscattering spectroscopy), NRA (nuclear reaction analysis) and laser Raman studies of high temperature corrosion  

SciTech Connect

This paper describes the basic principles of five surface and near surface analysis methods and explores ways they can be used to gather information relevant to oxidation and high temperature corrosion. The techniques discussed include: Auger electron spectroscopy, x-ray photoelectron spectroscopy, Rutherford backscattering spectroscopy, nuclear reaction analysis and laser Raman spectroscopy. Advantages and limitations of each method are highlighted. To illustrate the types of information available, four of the techniques have been used to examine the oxide formed on a nickel-chromium-thoria alloy. Other examples, original and from the literature, are used to demonstrate special characteristics of the techniques. Particular attention is devoted to the possibilities and limitations of high temperature studies in ultra high vacuum analytical systems.

Baer, D.R.; Dake, L.S.

1987-01-01

75

Structure and Electron Density Analysis of Lithium Manganese Oxides by Single-crystal X-ray Diffraction  

Microsoft Academic Search

Single crystals of LiMn2O4 and LiMnO2 have been successfully synthesized by a flux method. The lithium-ion deintercalated lambda-MnO2 single crystal has been prepared electrochemically using a microelectrode-based system. The single-crystal X-ray diffraction study at room temperature confirmed the cubic spinel Fd\\\\bar{3}m space group for LiMn2O4 and lambda-MnO2, and the orthorhombic Pmnm space group for LiMnO2, respectively. The crystal structure of

Yasuhiko Takahashi; Junji Akimoto; Yoshito Gotoh; Kaoru Dokko; Matsuhiko Nishizawa; Isamu Uchida

2003-01-01

76

X-ray Emission from Electron Betatron Motion in a Laser-Plasma Accelerator  

SciTech Connect

Single-shot x-ray spectra from electron bunches produced by a laser-plasma wakefield accelerator (LPA) were measured using a photon-counting single-shot pixelated Silicon-based detector, providing for the first time single-shot direct spectra without assumptions required by filter based techniques. In addition, the electron bunch source size was measured by imaging a wire target, demonstrating few micron source size and stability. X-rays are generated when trapped electrons oscillate in the focusing field of the wake trailing the driver laser pulse. In addition to improving understanding of bunch emittance and wake structure, this provides a broadband, synchronized femtosecond source of keV x-rays. Electron bunch spectra and divergence were measured simultaneously and preliminary analysis shows correlation between x-ray and electron spectra. Bremsstrahlung background was managed using shielding and magnetic diversion.

Plateau, G. R. [LOASIS Program at LBNL, Berkeley, CA 94720 (United States); Ecole Polytechnique, Palaiseau, 91128 (France); Geddes, C. G. R.; Matlis, N. H.; Mittelberger, D. E.; Battaglia, M.; Kim, T. S.; Nakamura, K.; Esarey, E.; Leemans, W. P. [LOASIS Program at LBNL, Berkeley, CA 94720 (United States); Thorn, D. B. [EMMI at GSI, Darmstadt, 64291 (Germany); Stoehlker, T. [APIX at GSI, Darmstadt, 64291 (Germany)

2010-11-04

77

Microbeam X-ray analysis in Poland - past and future  

NASA Astrophysics Data System (ADS)

The article provides an overview of the development of electron beam X-ray microanalysis (EPMA) in Poland. Since the introduction by Prof. Bojarski of EMPA over 45 years ago, tremendous advances in methodologies and in instrumentation have been made in order to improve the precision of quantitative compositional analysis, spatial resolution and analytical sensitivity. This was possible due to the activity of Applied Crystallography Committee at the Polish Academy of Sciences, as well as the groups of researches working in the Institute for Ferrous Metallurgy (Gliwice), the Technical University of Warsaw, the Silesian Technical University (Katowice), the AGH-University of Sciences and Technology (Krakow), and the Institute of Materials Science and Metallurgy Polish Academy of Sciences (Krakow). Based on the research examples realized by these teams, conferences, seminars and congresses organized, as well as books and academic textbooks issued, the evolution of electron beam X-ray microanalysis in Poland is demonstrated.

Kusinski, J.

2010-02-01

78

Exotic X-ray Sources from Intermediate Energy Electron Beams  

SciTech Connect

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. [Idaho Accelerator Center, Idaho State University, Pocatello, ID 83209 (United States); Jones, J.L.; Lancaster, G. [Idaho National Engineering and Environmental Laboratory, Idaho Falls, ID 83415-280 (United States)

2003-08-26

79

High gain harmonic generation x-ray free electron laser.  

National Technical Information Service (NTIS)

We present the calculation on the performance of a High Gain Harmonic Generation (HGHG) X-ray Free Electron Laser (FEL) based on the high quality electron beam from the proposed Photoinjected Energy Recovery Linac (PERL) at the NSLS. We consider several s...

Wu Yu

2001-01-01

80

Low Energy X-Ray and Electron Physics.  

National Technical Information Service (NTIS)

The research is concerned with a study of the complete interaction of the ultrasoft x-rays with matter in the 10-to-100 A wavelength region and of the associated production of photo and Auger electrons in the 10 to 1000 electron volt energy region. Such a...

B. L. Henke

1967-01-01

81

X-ray Emission from Electron Betatron Motion in a Laser-Plasma Accelerator  

SciTech Connect

Single-shot x-ray spectra from electron bunches produced by a laser-plasma wakefield accelerator (LPA) were measured using a photon-counting single-shot pixelated Silicon-based detector [3], providing for the first time direct spectra without assumptions required by filter based techniques. In addition, the electron bunch source size was measured by imaging a wire target, demonstrating few micron source size and stability. X-rays are generated when trapped electrons oscillate in the focusing field of the wake trailing the driver laser pulse. In addition to improving understanding of bunch emittance and wake structure, this provides a broadband, synchronized femtosecond source of keV x-rays. Electron bunch spectra and divergence were measured simultaneously and preliminary analysis shows correlation between x-ray andelectron spectra. Bremsstrahlung background was managed using shielding and magnetic diversion.

Plateau, Guillaume; Geddes, Cameron; Thorn, Daniel; Matlis, Nicholas; Mittelberger, Daniel; Stoehlker, T; Battaglia, Marco; Kim, Tae; Nakamura, Kei; Esarey, Eric; Leemans, Wim

2011-07-19

82

Research in quantitative microscopic X-ray fluorescence analysis  

Microsoft Academic Search

A feasibility study of quantitative elemental microanalysis of biological materials and glass samples by microbeam X-ray fluorescence spectroscopy was completed. The research included testing the homogeneity of existing standards for X-ray fluorescence calibration and verification of a fundamental parameters method for quantitative analysis. The goal was to evaluate the X-ray fluorescence spectrometer as a tool for elemental analysis at the

M. Lankosz; M. Szczerbowska-Boruchowska; J. Chwiej; J. Ostachowicz; A. Simionovici; S. Bohic

2004-01-01

83

Simultaneous Electron and X-Ray Spectrometry in a Scanning Transmission Electron Microscope.  

National Technical Information Service (NTIS)

This paper describes simultaneous EDXS and ELS analysis with an electron spectrometer and a UTW x-ray detector on a 100KV field emission gun STEM. Applications of this system used as examples include quantitative analyses of metal carbide and oxide phases...

L. E. Thomas

1983-01-01

84

X-Ray spectra and electronic structure of boron compounds  

NASA Astrophysics Data System (ADS)

The state-of-the-art in boron chemistry, the characteristic features of boron compounds and crystalline phases based on them, the chemical bonds in these compounds and their electronic structures are considered. The physical principles of X-ray spectroscopy and the results it provided on the chemical structures of boron compounds and the nature of chemical bonds in them are discussed. Data for X-ray photoelectron and ultraviolet photoelectron spectroscopies for various elemental boron modifications, boron oxide phases, borides, nitrides, halides, derivatives of boron hydrides and carboranes, as well as metalloboranes are compared.

Yumatov, Vladimir D.; Il'inchik, Evgenii A.; Volkov, Vladimir V.

2003-12-01

85

Remineralization of enamel subsurface lesions with casein phosphopeptide-amorphous calcium phosphate: A quantitative energy dispersive X-ray analysis using scanning electron microscopy: An in vitro study  

PubMed Central

Aim: The objective of this study was to quantitatively evaluate the remineralization potential of casein phosphopeptide-amor-phous calcium phosphate paste on enamel subsurface lesions using scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX). Materials and Methods: Ninety enamel specimens were prepared from extracted human molars. All specimens were evaluated for mineral content (% weight) using SEM-EDX. The specimens were placed in demineralizing solution for four days to produce artificial carious lesions. The mineral content (calcium/phosphorus ratios, Ca/P ratios) was remeasured using SEM-EDX. The specimens were then randomly assigned to five study groups and one control group of 15 specimens per group. Except for the control group, all group specimens were incubated in remineralizing paste (CPP-ACP paste) for 7, 14, 21, 28, and 35 days twice daily for three minutes. The control group received no treatment with remineralizing paste. All the 90 specimens were stored in artificial saliva at 37°C. After remineralization, the mineral content (% weight) of the samples was measured using SEM-EDX. Results: All the study groups showed very highly significant differences between Ca/P ratios of the demineralized and remineralized samples. There was no significant difference seen in the control group. Conclusion: CPP-ACP paste could significantly remineralize the artificial enamel subsurface lesions in vitro: the remineralizing rates increasing with the time for which the samples were kept in the remineralizing paste. Energy dispersive X-ray analysis is an efficient way to quantitatively assess the changes in mineral content during demineralization and in vitro remineralization processes.

Hegde, Mithra N; Moany, Anu

2012-01-01

86

Electron probe X-ray microanalysis of human muscle biopsies  

Microsoft Academic Search

The elemental composition of human muscle fibres have been determined by electron probe microanalysis. In order to distinguish between different types of fibres, two approaches were used. In one approach individual fibres were isolated, portions of them used for a typing by histochemical methods and the main part used for X-ray microanalysis. In the other approach the muscle biopsy was

Romuald Wroblewski; Godfried M. Roomans; Eva Jansson; Lars Edström

1978-01-01

87

Thomson-Backscattered X Rays From Laser-Accelerated Electrons  

Microsoft Academic Search

We present the first observation of Thomson-backscattered light from laser-accelerated electrons. In a compact, all-optical setup, the ``photon collider,'' a high-intensity laser pulse is focused into a pulsed He gas jet and accelerates electrons to relativistic energies. A counterpropagating laser probe pulse is scattered from these high-energy electrons, and the backscattered x-ray photons are spectrally analyzed. This experiment demonstrates a

H. Schwoerer; B. Liesfeld; H.-P. Schlenvoigt; K.-U. Amthor; R. Sauerbrey

2006-01-01

88

Proposal for a Raman X-ray free electron laser  

Microsoft Academic Search

.  \\u000a A scheme for an X-ray free electron laser is proposed, based on a Raman process occurring during the interaction between a\\u000a moderately relativistic bunch of free electrons, and twin intense short pulse lasers interfering to form a transverse standing\\u000a wave along the electron trajectories. In the high intensity regime of the Kapitza-Dirac effect, the laser ponderomotive potential\\u000a forces the

Philippe Balcou

2010-01-01

89

An X-ray Analysis of ? Cru  

NASA Astrophysics Data System (ADS)

The star ? Cru is an early B type subgiant star recently observed by the Chandra Space Telescope. This star is of particular interest due to the observed x-ray emission produced by shocks that form in the stellar wind. We observe hydrogen like O VIII and helium like O VII spectral lines in the Low Energy Transmission Grating spectrum. The O VII produces characteristic triplet line. We provide an analysis of the helium like triplet that explains the conditions in the stellar wind where that line emission is formed. ? Cru is also an ultraviolet bright star, so an International Ultraviolet Explorer observation is used to explain the effect of ultraviolet pumping on the forbidden component of the ? triplet line. The data appear basically consistent with theoretical models of shocks in stellar winds by Owocki, Caster, & Rybicki (1988) and Feldmeier et al. (1997). This project was funded by a partnership between the National Science Foundation (NSF AST-0552798), Research Experiences for Undergraduates (REU), and the Department of Defense (DoD) ASSURE (Awards to Stimulate and Support Undergraduate Research Experiences) programs.

Gorski, Mark; Ignace, R.; Oskinova, L.

2010-01-01

90

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.

Hans P. Bluem; Alan M. M. Todd; Ilan Ben-Zvi; Michael D. Cole; Pat Colestock; Dietmar Janssen; John W. Lewellen; George R. Neil; Dinh C. Nguyen; Larry Phillips; Joe Preble; John Rathke; Tom Schultheiss; Triveni Srinivasan-Rao; Richard L. Wood; Lloyd M. Young

2004-11-01

91

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

92

An ultra fast electron beam x-ray tomography scanner  

NASA Astrophysics Data System (ADS)

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 beam generator with a fast beam deflection unit, a semicircular x-ray production target made of tungsten alloy and a circular x-ray detector consisting of 240 CZT elements with 1.5 mm × 1.5 mm × 1.5 mm size each. The design is optimized with respect to ultra fast imaging of smaller flow vessels, such as pipes or laboratory-scale chemical reactors. In that way, the scanner is capable of scanning flow cross-sections at a speed of a few thousand frames per second which is sufficient to capture flows of a few meters per second velocity.

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

2008-09-01

93

Atomic inner-shell x-ray laser pumped by an x-ray free-electron laser  

SciTech Connect

We discuss possibilities of pumping an atomic inner-shell x-ray laser with an x-ray free-electron laser (XFEL). Self-consistent gain calculations show that with the first available XFEL, the Linac Coherent Light Source at Stanford, it will become possible to produce subfemtosecond x-ray pulses at intensities reaching 6x10{sup 16} W/cm{sup 2}. Small-signal gain calculations indicate that saturation of more than one lasing line is possible, resulting in temporally separated femtosecond x-ray pulses of different wavelengths. The presented lasing scheme creates broad capability for advancing the field of high-intensity ultrashort x-ray physics.

Rohringer, Nina; London, Richard [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

2009-07-15

94

An optimal design of X-ray target for uniform X-ray emission from an electronic brachytherapy system  

NASA Astrophysics Data System (ADS)

We present a novel design of an X-ray target to deliver uniform dose from an electronic brachytherapy system (EBS). This design comprises of a combination of both the reflection- and transmission-type target geometries. Monte-Carlo simulation code MCNP5 has been employed for the calculation of angular distribution of the X-ray intensity produced from various morphologies of X-ray targets. The simulation results reveal that the combinatorial target-assembly is promising and effective in achieving uniformity of X-ray emission over the entire space of solid angle of 4? in comparison to a transmission-type target that produces X-rays mainly in the forward direction and a reflection-type target that generates X-rays mostly in the backward direction. As a direct consequence of the uniformity of X-ray emission, the combinatorial target-assembly can impart a uniform dose distribution which makes it suitable as a target of an X-ray tube for EBS.

Ihsan, Aamir; Heo, Sung Hwan; Kim, Hyun Jin; Kang, Chang Mu; Cho, Sung Oh

2011-05-01

95

New Developments in Data for Auger Electron Spectroscopy and X- ray Photoelectron Spectroscopy  

Microsoft Academic Search

A brief description is given of three recent developments concerning the generation and application of data for elastic and inelastic scattering of electrons relevant to Auger-electron spectroscopy (AES) and X-ray photoelectron spectroscopy. First, an extensive analysis of calculated and measured differential cross sections for elastic scattering of electrons by atoms has been published. Second, new calculations have been made of

C. J. Powell; A. Jablonski; F. Salvat; S. Tanuma; D. R. Penn

96

Fundamental studies of X-ray and secondary electron spectroscopy  

Microsoft Academic Search

Microanalysis of submicron particles in the Scanning Electron Microscope (SEM) is only possible by using low incident electron beam energies due to smaller interaction volume and suppressed beam induced charging. Such low beam energies must use L- and M-lines rather than the familiar K-lines. The information about the fundamental parameters of X-ray emission and transport at low energies is limited,

Satya Prasad Mulapudi

2004-01-01

97

Pair creation and an x-ray free electron laser.  

SciTech Connect

Using a quantum kinetic equation we study the possibility that focused beams at proposed x-ray free electron laser facilities can initiate spontaneous electron-positron pair production from the QED vacuum. Under conditions reckoned achievable at planned facilities, repeated cycles of particle creation and annihilation will take place in tune with the laser frequency. The peak particle number density is insensitive to this frequency, and one can anticipate the production of a few hundred particle pairs per laser period.

Alkofer, R.; Hecht, M. B.; Roberts, C. D.; Schmidt, S. M.; Vinnik, D. V.; Physics; Univ. Tubingen

2001-11-05

98

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...

99

Analysis of X-Ray (L) Spectra of Heavy Elements.  

National Technical Information Service (NTIS)

The general problem of obtaining and analysing spectra is presented, with emphasis in the comparison of methods for the analysis of gamma rays and X rays. The method proposed to obtain a standard and later the intensities of lines of an X-ray (L) spectrum...

L. F. de Souza Coelho

1976-01-01

100

Near Edge X-Ray Absorption Fine Structure Spectroscopy with X-Ray Free-Electron Lasers  

SciTech Connect

We demonstrate the feasibility of Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy on solids by means of femtosecond soft x-ray pulses from a free-electron laser (FEL). Our experiments, carried out at the Free-Electron Laser at Hamburg (FLASH), used a special sample geometry, spectrographic energy dispersion, single shot position-sensitive detection and a data normalization procedure that eliminates the severe fluctuations of the incident intensity in space and photon energy. As an example we recorded the {sup 3}D{sub 1} N{sub 4,5}-edge absorption resonance of La{sup 3+}-ions in LaMnO{sub 3}. Our study opens the door for x-ray absorption measurements on future x-ray FEL facilities.

Bernstein, D.P.; Acremann, Y.; Scherz, A.; Burkhardt, M.; Stohr, J.; /SLAC; Beye, M.; Schlotter, W.F.; Beeck, T.; Sorgenfrei, F.; Pietzsch, A.; Wurth, W.; Fohlisch, A.; /Hamburg U.

2009-12-11

101

X-ray analysis of solid solutions  

Microsoft Academic Search

The atomic structure of solid solutions of copper-aluminium, aluminium-magnesium, and copper-nickel has been examined by the X-ray spectrometer. In each case it was found that the solute atom replaces an atom in the lattice of the solvent, the substitution being accompanied by a distortion of the lattice.A saturated solution of aluminium in copper shows that the aluminium expands the copper

E A Owen; G D Preston

1923-01-01

102

Interactions of clusters with X-ray free electron laser  

Microsoft Academic Search

In order to investigate the damage of a single bio-molecule when it is irradiated by a strong X-ray free electron laser (XFEL) pulse, time evolution of a single carbon cluster with diameter of 30 nm irradiated with 10-fs XFEL pulse is studied by using particle-in-cell (PIC) code including field-ionization and collisional ionization. The cluster is ionized up to C^4+ within

Yuji Fukuda; Tatsufumi Nakamura; Kengo Moribayashi; Yasuaki Kishimoto

2008-01-01

103

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

NASA Astrophysics Data System (ADS)

The X-Ray Spectrometer (XRS) onboard the MESSENGER spacecraft measures elemental abundances on the surface of Mercury by detecting fluorescent X-ray emissions induced on the planet's surface by the incident solar X-ray flux. The most prominent fluorescent lines are the K? lines from the elements Mg, Al, Si, S, Ca, Ti, and Fe (1-10 keV). 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 measureable 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. To date, seven 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 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, providing additional measurement opportunities for the XRS.

Starr, R. D.; Nittler, L. R.; Weider, S. Z.; Rhodes, E. A.; Schriver, D.; Schlemm, C. E., II; Solomon, S. C.

2011-12-01

104

X-Ray Photon Correlation Spectroscopy at the European X-Ray Free-Electron Laser (XFEL) facility  

Microsoft Academic Search

The proposed European X-ray Free-Electron Laser source (XFEL) will provide extremely brilliant (B>1033 ph\\/s\\/mm2\\/mrad2\\/0.1% bw) and highly coherent X-ray beams. Due to the pulse structure and the unprecedented brightness one will be able 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

Gerhard Grübel

2008-01-01

105

Raman microspectroscopy as a valuable additional method to X-ray diffraction and electron microscope/microprobe analysis in the study of iron arsenates in environmental samples.  

PubMed

In this paper, we demonstrate that combined application of X-ray diffraction (XRD), electron microscope/microprobe analysis (EMPA), and Raman microspectroscopy is an available and powerful approach for identification and characterization of iron arsenate minerals in complex environmental samples. Arsenic-rich material from the medieval mining dump close to the Giftkies mine in the Jáchymov ore district (Czech Republic) has been studied. Scorodite, kankite, amorphous iron arsenate (pitticite), and, to a lesser extent, native sulfur were determined in the studied samples as products of low-temperature arsenopyrite weathering. Scorodite and kankite form mixed nodules and crusts, which are locally coated by hardened gel-like amorphous pitticite. Pitticite also borders fractures in the mineralized rock fragments in the dump. Native sulfur, in microscopic crystals and grainy aggregates, originates directly in places with dissolved arsenopyrite and forms pseudomorphs. The Raman spectra presented in the paper can serve as comparative data for phase identification in other contaminated areas. New Raman data for the hydroxyl stretching region of scorodite (important bands: 3514, 3427, and 3600 cm(-1)) and the whole Raman spectrum for pitticite (important bands: 472, 831, 884, 2935, 3091, 3213, 3400, and 3533 cm(-1)) are a valuable output of this paper. PMID:19531289

Filippi, Michal; Machovic, Vladimír; Drahota, Petr; Böhmová, Vlasta

2009-06-01

106

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

107

Synchrotron X-ray analysis of the electron density in CoF2 and ZnF2.  

PubMed

Accurate structure factors for small crystals of the rutile-type structures CoF(2), cobalt difluoride, and ZnF(2), zinc difluoride, have been measured with focused lambda = 0.8400 (2) A synchrotron X-radiation at room temperature. Phenomenological structural trends across the full series of rutile-type transition metal difluorides are analysed, showing the importance of the metal atom in the degree of distortion of the metal-F(6) octahedra in these structures. Multipole models reveal strong asphericities in the electron density surrounding the transition metals, which are consistent with expectations from crystal field theory and the structural trends in these compounds. Transition metal 3d-orbital populations were computed from the multipole refinement parameters, showing significant repopulation of orbitals compared with the free atom, particularly for CoF(2). PMID:11262426

O'Toole, N J; Streltsov, V A

2001-04-01

108

Axial electron density of human scleral collagen. Location of proteoglycans by x-ray diffraction.  

PubMed Central

The low angle meridional x-ray diffraction pattern from fresh human sclera was analyzed to ascertain if collagen-bound proteoglycans affect the axially-projected electron density distribution to the same extent as appears to occur in the cornea. The results showed that, unlike cornea, the electron density of the sclera is similar to that seen in rat tail tendon collagen. The proteoglycans were specifically stained using either Cuprolinic blue or Cupromeronic blue, both under critical electrolyte conditions. The tissue was then examined by electron microscopy and by low angle x-ray diffraction. The electron-optical observations suggested that proteoglycans associate with collagen near the d/e staining bands in the gap zone. A difference Fourier analysis from the x-ray results confirmed that these observations were not e.m. preparative artefacts and allowed a quantitative estimate to be made of the axial extent of the proteglycans in the wet tissue. Images FIGURE 1 FIGURE 3

Quantock, A J; Meek, K M

1988-01-01

109

Soft X-ray Analysis and Multiwavelength Modeling of X-ray Selected Active Galactic Nuclei  

Microsoft Academic Search

We survey the broadband spectral properties of ~500 X-ray-selected Active Galactic Nuclei (AGN) observed with the Einstein X-ray Observatory in order to better understand the X-ray emission characteristics of this population as compared to previously studied optically- and radio-selected populations. We further select a subsample of X-ray-selected AGN which possess strong components of soft X-ray emission below ~0.5 keV. This

Richard J. Thompson

1994-01-01

110

Total-electron-yield x-ray standing-wave measurements of multilayer x-ray mirrors for the interface structure evaluation  

Microsoft Academic Search

Summary form only given. Total-electron-yield (TEY) x-ray standing-wave spectra of multilayer x-ray mirrors by monitoring sample photocurrent are presented to obtain information on their interface structure. This simple TEY x-ray standing-wave method enables simultaneous spectral measurements of the x-ray standing-wave and Bragg reflection. Optical measurements of Bragg reflection and x-ray standing-waves were carried out by using the reflectometer installed in

Y. Muramatsu; L. Takenaka; E. M. Gullikson; R. C. C. Perera

2001-01-01

111

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

112

Electron probe X-ray microanalysis of rabbit ciliary epithelium.  

PubMed

Rabbit iris-ciliary bodies were preincubated in control and experimental Ringer's solutions before quick freezing, cryosectioning, dehydration and electron probe X-ray microanalysis. After preincubation in a baseline bicarbonate-free Cl- Ringer's solution, the ciliary epithelial intracellular Na+, K+ and Cl- concentrations were estimated to be 15 +/- 3, 162 +/- 14 and 46 +/- 5 mmol kg-1 intracellular water, respectively. The water and elemental Na, K, Cl and P contents were similar in the non-pigmented (NPE) and pigmented (PE) ciliary epithelial cells. As expected, inhibition of the Na,K-exchange pump by preincubation with ouabain markedly increased the intracellular Na content, and markedly reduced the intracellular K content, verifying the validity of the experimental analysis. The Cl- channels of the NPE cells likely play a critical role in determining the rate of aqueous humor formation. Therefore, we have examined the effects of altering Cl- transport on the intracellular composition in this initial microprobe study of the ciliary epithelium. As expected, exposure to bicarbonate increased the intracellular Cl and water contents. Replacement of external Cl- by NO3- was twice as effective as replacement by gluconate in leaching Cl- out of the intracellular compartment. An unexpected finding was that NO3- replacement of internal Cl- substantially increased the intracellular Na and decreased the intracellular K content, possibly by stabilizing the Na,K-pump in the E1P form and inhibiting enzyme activity. PMID:8698073

Bowler, J M; Peart, D; Purves, R D; Carré, D A; Macknight, A D; Civan, M M

1996-02-01

113

X-ray optics power considerations for high intensity x-ray free-electron lasers based on superconducting technology  

NASA Astrophysics Data System (ADS)

X-ray free-electron lasers generate ultrashort and very intense x-ray radiation in the wavelength domain reaching from the VUV (100 nm and shorter) all the way to the hard x-ray domain (typically 0.1 nm). FEL radiation features extreme brilliance, ultrashort pulse duration, and high peak power. Superconducting accelerators provide furthermore the possibility to accelerate a large number of electron bunches during a single radio-frequency pulse. Likewise the total number of x-ray pulses available for the experiments is increased leading to a significantly higher average brilliance. FEL light sources, and those based on super-conducting accelerator technology, are therefore considered to provide a new quality of short wavelength radiation if compared to existing x-ray sources. The high intensity and the high repetition rate lead to new requirements for x-ray optics in terms of peak and average power. Values for peak and average power are presented in relation to the proposed realization of the photon beamlines at the European XFEL facility.

Tschentscher, Th.; Sinn, H.; Tiedtke, K.; Wabnitz, H.

2007-05-01

114

Polarization Excitation Device for X-Ray Fluorescence Analysis.  

National Technical Information Service (NTIS)

The patent application is a device for improving the sensitivity for elemental analysis by X-ray fluorescence using energy dispersive detectors. Samples are analyzed for their trace elemental composition by irradiating the samples with a beam of nearly mo...

T. G. Dzubay

1974-01-01

115

Monte Carlo Modeling of Generation of Characteristic, Continuous and Fluorescent X-rays by Electron Impact  

NASA Astrophysics Data System (ADS)

A Monte Carlo (MC) simulation to calculate the absolute intensity of an X-ray spectrum generated by electron impact was developed. The X-ray spectrum consists of continuous and characteristic X-rays excited by primary electron, and fluorescent X-rays due to the absorption of the continuous and characteristic X-rays. The comparison of the simulated X-ray spectra with the experimental ones showed excellent agreement for bulk Al, Sc, Ge and Zr. The quantitative investigations of the simulated intensity of the characteristic K peak and the effect of the fluorescent X-ray were performed. It was confirmed that the developed MC simulation is applicable not only for optimizing the design of the rotor-type X-ray source to develop a high-brightness wavelength-tunable X-ray source, but also for quantitative electron probe microanalysis.

Nagatomi, Takaharu; Hibi, Takaaki; Takai, Yoshizo; Obori, Ken-ichi; Awata, Syogo; Yurugi, Toshikazu

2003-10-01

116

HIGH GAIN HARMONIC GENERATION X-RAY FREE ELECTRON LASER.  

SciTech Connect

We present the calculation on the performance of a High Gain Harmonic Generation (HGHG) X-ray Free Electron Laser (FEL) based on the high quality electron beam from the proposed Photoinjected Energy Recovery Linac (PERL) at the NSLS. We consider several sets of e-beam parameters. The calculation indicates that it is possible to produce a fully coherent FEL with a wavelength around 10 Angstrom, with a peak power of several GW. The high order harmonics will also be produced with a significant amount of peak power. One further attractive feature is the possibility to produce ultra short radiation pulses of about 10 fs based on such HGHG scheme.

WU, J.; YU, L.H.

2001-06-18

117

Femtosecond Nanocrystallography with X-ray Free-Electron Lasers  

NASA Astrophysics Data System (ADS)

The ultrafast pulses from X-ray free-electron lasers have opened up a new form of protein nanocrystallography. The X-ray pulses are of high enough intensity and of sufficiently short duration that individual single-shot diffraction patterns can be obtained from a sample before significant damage occurs. This "diffraction before destruction" method may enable the determination of structures of proteins that cannot be grown into large enough crystals or are too radiation sensitive for high- resolution crystallography. Ultrafast pump-probe studies of photoinduced dynamics can also be studied. We have carried out experiments in coherent diffraction from protein nanocrystals, including Photosystem I membrane protein, at the Linac Coherent Light Source (LCLS) at SLAC. The crystals are filtered to sizes less than 2 micron, and are delivered to the pulsed X-ray beam in a continuously flowing liquid jet. Millions of diffraction patterns were recorded at the LCLS repetition rate of 60 Hz. Tens of thousands of the single-shot diffraction patterns have been indexed, and combined into a single crystal diffraction pattern, which can be phased for structure determination and analysed for the effects of pulse duration and fluence. Experimental data collection was carried out as part of a large collaboration involving CFEL DESY, Arizona State University, Max Planck Institute for Medical Research, University of Uppsala, SLAC, LBNL, LLNL, using the CAMP apparatus which was designed and built by the Max Planck Advanced Study Group at CFEL.

Chapman, Henry

2011-03-01

118

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

119

Calculation of x-ray spectra emerging from an x-ray tube. Part I. Electron penetration characteristics in x-ray targets  

Microsoft Academic Search

The penetration characteristics of electron beams into x-ray targets are investigated for incident electron kinetic energies in the range 50-150 keV. The frequency densities of electrons penetrating to a depth x in a target, with a fraction of initial kinetic energy, u, are calculated using Monte Carlo methods for beam energies of 50, 80, 100, 120 and 150 keV in

Gavin G. Poludniowski; Philip M. Evans

2007-01-01

120

Analysis of paramagnetic centers in X-ray-irradiated enamel, bone, and carbonate-containing hydroxyapatite by electron spin resonance spectroscopy  

Microsoft Academic Search

Summary  Carbonate-containing hydroxyapatite, enamel, and bone were irradiated by an X-ray and investigated between 77 and 350K by\\u000a means of electron spin resonance (ESR) spectroscopy.\\u000a \\u000a The ESR spectrum of enamel irradiated at 77K in vacuum and observed at the same temperature was almost the same as that of\\u000a the carbonate-containing hydroxyapatite. The temperature dependence of signal intensities confirms a spin-energy exchange

Y. Doi; T. Aoba; M. Okazaki; J. Takahashi; Y. Moriwaki

1979-01-01

121

Proton-Induced X-Ray Emission Analysis  

Microsoft Academic Search

The aim of this thesis is to establish a solid mathematical basis for the use of thick target Proton Induced X-ray Emission (PIXE) analysis to the determination of trace element concentrations in solid samples. With the advent of high resolution Si(Li) detectors there was a revival of interest in the use of characteristic X-rays induced by high energy particle beams.

Eric John Clayton

1989-01-01

122

An Automated X-Ray Gauge for Nondestructive Quantitative Analysis  

Microsoft Academic Search

An x-ray gauging system is described for nondestructive quantitative analysis. The automated device utilizes the transmission of low-energy x-rays through a material in order to measure the areal density of the material. Under some conditions, one material may be examined in the presence of another. Using digital rather than analog conversion techniques, measurement precision of 0.1% and accuracy near 0.5%

William D. Drotning

1988-01-01

123

Characteristic x-rays from (n, ?) products and their utilization in activation analysis  

Microsoft Academic Search

The possibility of using characteristic X-rays from radioactive elements in activation analysis was investigated during this\\u000a work with particular emphasis on (n, ?) products. At least 27 of 56 elements investigated during this work were found to yield\\u000a themselves to activation analysis employing characteristic X-rays from electron capture or internal conversion processes during\\u000a isomeric transition.\\u000a \\u000a In presenting the results, a

K. K. S. Pillay; W. W. Miller

1969-01-01

124

Basic studies on x-ray fluorescence analysis for active x-ray spectrometer on SELENE-2  

NASA Astrophysics Data System (ADS)

An active X-ray spectrometer (AXS) is now being developed as a payload candidate for the rover on SELENE-2, the next Japanese lunar exploration mission. The AXS will determine the chemical compositions of lunar rocks and regolith around the landing site. The surface of lunar rock samples will be ground using a rock abrasion tool. Thus, fundamental studies on the X-ray fluorescence analysis for lunar rocks and regolith are required to design and develop the AXS. In this study, we have investigated the X-ray fluorescence analysis in order to evaluate the effects of surface roughness of samples and the angle of incident and emergent X-rays. It was found that the fluorescent X-ray yield for low energy X-rays, i.e. the light elements, decreases at rough surface samples. This effect of surface roughness becomes small for smooth surface samples. It was also found that the fluorescent X-ray yield depends on the incident angle, which is attributed to the fact that the X-ray fluorescence occurs closer to the sample surface at larger incident angles. Since the emergent X-rays are affected by the detection geometry and surface roughness, the incident angle effect also depends on the above conditions.

Kusano, Hiroki; Hasebe, Nobuyuki; Nagaoka, Hiroshi; Kodama, Takuro; Oyama, Yuki; Tanaka, Reiko; Amano, Yoshiharu; Kim, Kyeong J.; Matias Lopes, Josè A.

2013-09-01

125

X-ray waveguides for high resolution x-ray analysis  

Microsoft Academic Search

The project goals were to model, synthesize, and characterize thin-film, x-ray waveguide structures to determine whether such nanostructurcs can be fabricated with the precision required for true waveguide operation at x-ray energies. In FY98, we designed, fabricated, and characterized (at the Stanford Synchrotron Radiation Laboratory) optimized. thin-film, x-ray waveguide structures (XWGs) as resonant concentrators of x-rays which may be applied

Barbee

1999-01-01

126

Quantitative x-ray fluorescence analysis using monochromatic synchrotron radiation  

SciTech Connect

The use of high-intensity, tunable monochromatic x-rays for the quantitative analysis of biological and geochemical specimens at the 10/sup -8/ g level is described. Incident x-rays were obtained from the new LBL-EXXON permanent magnet wiggler beamline at the Stanford Synchrotron Radiation Laboratory. The sample detector geometry was designed to make optimal use of polarization advantages for background reduction. Questions regarding the sensitivity and accuracy of the measurements were studied with particular emphasis on the advantages of tuning the x-ray energies for optimum excitation for specific elements. The implications of these measurements with respect to the use of x-ray microprobe beams will be discussed.

Jaklevic, J.M.; Giauque, R.D.; Thompson, A.C.

1984-09-01

127

X-ray fluorescence analysis based on Kumakhov optics  

NASA Astrophysics Data System (ADS)

The use of Kumakhov optics in x-ray fluorescence analysis is considered. Thanks to high efficiency of a polycapillary lens the concentration of x-ray detector in a close proximity to the sample decreases sufficiently the time of exposure. It is shown experimentally that in the case of use of a small x-ray source with power of 2W the minimal detection limit may be of the order of 0.1 pg. A new portable x-ray fluorescence analyzer based on Kumakhov optics is described. Minimal detection limit may achieve 10(superscript -16) g if 100 W microfocus source and the lens with approximately 10 micrometers focal spot are used.

Nikitina, Svetlana V.; Ibraimov, Nariman S.; Stcherbakov, Alexander S.

1998-11-01

128

Defect Analysis in Crystals using X-ray Topography  

SciTech Connect

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 imperfections. Mechanisms of contrast formation on X-ray topographs are discussed, with emphasis on contrast associated with dislocations. Determination of Burgers vectors and line directions of dislocations from analysis of X-ray topographs is explained. Contrast from inclusions is illustrated, and their differentiation from dislocations is demonstrated with the aid of simulated topographs. Contrast arising from the deformation fields associated with cracks is also briefly covered.

Raghothamachar,B.; Dhanaraj, G.; Bai, J.; Dudley, M.

2006-01-01

129

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

130

X-Ray diffraction and scanning electron microscopy-energy dispersive spectroscopic analysis of ceram?metal interface at different firing temperatures  

PubMed Central

Objective: Porcelain chipping from porcelain fused to metal restoration has been Achilles heel till date. There has been advent of newer ceramics in past but but none of them has been a panacea for Porcelain fracture. An optimal firing is thus essential for the clinical success of the porcelain-fused to metal restoration. The aim of the present study was to evaluate ceramo-metal interface at different firing temperature using XRD and SEM-EDS analysis. Clinical implication of the study was to predict the optimal firing temperature at which porcelain should be fused with metal in order to possibly prevent the occasional failure of the porcelain fused to metal restorations. Materials and Methods: To meet the above-mentioned goal, porcelain was fused to metal at different firing temperatures (930–990°C) in vacuum. The microstructural observations of interface between porcelain and metal were evaluated using X-ray diffraction and scanning electron microscopy with energy dispersive spectroscopy. Results: Based on the experimental investigation of the interaction zone of porcelain fused to metal samples, it was observed that as the firing temperature was increased, the pores became less in number as well as the size of the pores decreased at the porcelain/metal interface upto 975°C but increased in size at 990°C. The least number of pores with least diameter were found in samples fired at 975°C. Several oxides like Cr2O3, NiO, and Al2O3 and intermetallic compounds (CrSi2, AlNi3) were also formed in the interaction zone. Conclusions It is suggested that the presence of pores may trigger the crack propagation along the interface, causing the failure of the porcelain fused to metal restoration during masticatory action.

Saini, Monika; Chandra, Suresh; Singh, Yashpal; Basu, Bikramjit; Tripathi, Arvind

2010-01-01

131

Visible/IR light and x-rays in femtosecond synchronism from an x-ray free-electron laser.  

SciTech Connect

A way is proposed to obtain pulses of visible/infrared light in femtosecond synchronism with x-rays from an x-ray free-electron laser (XFEL), using the recently proposed emittance-slicing technique. In an XFEL undulator, only the short section of an electron bunch whose emittance is left unchanged by the slicing will emit intense coherent x-rays in the XFEL undulator. At the same time, the bunch emits highly collimated transition undulator radiation (TUR) into a cone whose opening angle is the reciprocal relativisticity parameter gamma. Due to the variation of the transverse momentum induced by the emittance slicing, the effective number of charges contributing to the TUR varies along the bunch, and is higher in the sliced-out part that emits the coherent x-rays. As with coherent synchrotron radiation (CSR), the TUR is thus coherently enhanced (CTUR) at near-infrared wavelengths. Coming from the same part of the bunch the CTUR and the coherent x-rays are perfectly synchronized to each other. Because both types of radiation are generated in the long straight XFEL undulator, there are no dispersion effects that might induce a timing jitter. With typical XFEL parameters, the energy content of the single optical cycle of near-IR CTUR light is about 100 Nano-Joule, which is quite sufficient for most pump-probe experiments.

Adams, B. A.; Experimental Facilities Division (APS)

2005-01-01

132

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

SciTech Connect

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. [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041 (China)

2009-12-15

133

X-ray absorption and soft x-ray fluorescence analysis of KDP optics  

SciTech Connect

Potassium Dihydrogen Phosphate (KDP) is a non-linear optical material used for laser frequency conversion and optical switches. Unfortunately, when KDP crystals are coated with a porous silica anti-reflection coating [1] and then exposed to ambient humidity, they develop dissolution pits [2,3]. Previous investigations [2] have shown that thermal annealing renders KDP optics less susceptible to pitting suggesting that a modification of surface chemistry has occurred. X-ray absorption and fluorescence were used to characterize changes in the composition and structure of KDP optics as a function of process parameters. KDP native crystals were also analyzed to provide a standard basis for interpretation. Surface sensitive total electron yield and bulk sensitive fluorescence yield from the K 2p, P 2p (L{sub 2,3}-edge) and O 1s (K-edge) absorption edges were measured at each process step. Soft X-ray fluorescence was also used to observe changes associated with spectral differences noted in the absorption measurements. Results indicate that annealing at 160 C dehydrates the surface of KDP resulting in a metaphosphate surface composition with K:P:O = 1:1:3.

Nelson, A J; van Buuren, T; Miller, E; Land, T A; Bostedt, C; Franco, N; Whitman, P K; Baisden, P A; Terminello, L J; Callcott, T A

2000-08-09

134

Limitations of ZAF correction factors in the determination of calcium\\/phosphorus ratios: Important forensic science considerations relevant to the analysis of bone fragments using scanning electron microscopy and energy-dispersive x-ray microanalysis  

Microsoft Academic Search

A series of calcium phosphate standards having calcium\\/phosphorus (Ca\\/P) molar ratios of 0.50, 1.00, 1.50, and 1.67, respectively, was prepared for bulk specimen analysis using scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDXA). The standards were mounted on carbon planchettes as either pure crystals or crystals embedded in epoxy resin. Ten different samples of each embedded and non-embedded standard

C. M. Payne; D. W. Cromey

1990-01-01

135

Studies of electron beams and X-Rays within different plasma-focus devices  

NASA Astrophysics Data System (ADS)

The paper presents a summary of investigations, which were performed with two mediumsize Plasma-Focus (PF) facilities, operated at IPJ in Swierk, Poland, during the recent few years. Attention is paid to experiments performed with MAJA-PF and PF-360 devices. which were run within the energy range from 37 kJ to 170 kJ. To analyze the emitted electron beams (e-beams) and X-rays, the use was made of different time-integrated and time-resolved diagnostic techniques, e.g. Cerenkov detectors, magnetic analyzers, vacuum X-ray pinhole cameras and scintillation detectors. A qualitative and quantitative analysis of the obtained results has been performed. The correlation of relativistic e-beams and X-ray pulses with other PF phenomena has also been discussed.

Zebrowski, J.; Sadowski, M. J.; Jakubowski, L.

2004-03-01

136

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

137

X ray computed tomography for failure analysis investigations  

Microsoft Academic Search

Failure analysis is an important engineering evaluation in any product development cycle; it is essential to product reliability and evolution. The volumetric feature detection and three-dimensional positioning capability of X-ray computed tomography are valuable and cost saving assets to a failure analysis laboratory. Savings are realized in reduced risk, determination of proper direction for irreversible failure analysis activities, and schedule

Richard H. Bossi; William Shepherd

1993-01-01

138

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

Microsoft Academic Search

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

I. D. Feranchuk; A. S. Lobko

2008-01-01

139

Electron probe X-ray analysis on human hepatocellular lysosomes with copper deposits: copper binding to a thiol-protein in lysosomes  

SciTech Connect

Livers of eight patients with chronic liver diseases were investigated by energy dispersive x-ray analysis. First, three kinds of preparations (osmium-Epon sections, glutaraldehyde-frozen sections, and unfixed-frozen sections) were compared for element detectability at a subcellular level. The glutaraldehyde-frozen sections were satisfactory as far as copper, sulfur, and phosphorus were concerned. Five patients (one patient with Wilson's disease, one chronic cholestasis, one chronic hepatitis, and two asymptomatic primary biliary cirrhosis) yielded x-ray images of copper and sulfur consistent with hepatocellular lysosomes. Second, the glutaraldehyde-frozen sections were utilized for a study of copper deposits in the patients' livers. There was a significant correlation between copper and sulfur contents in the lysosomes of all patients studied but no correlation in the remainder of the cytoplasm. Zinc was not detected in the lysosomes. Whatever the content of copper in the lysosomes, the ratio of delta copper to phosphorus (weight/weight) to delta sulfur to phosphorus was 0.60. These data indicate that most lysosomal copper binds to a thiol protein, probably metallothionein, in the liver.

Hanaichi, T.; Kidokoro, R.; Hayashi, H.; Sakamoto, N.

1984-11-01

140

Remineralization of demineralized enamel by toothpastes: a scanning electron microscopy, energy dispersive X-ray analysis, and three-dimensional stereo-micrographic study.  

PubMed

Remineralization of hard dental tissues is thought to be a tool that could close the gap between prevention and surgical procedures in clinical dentistry. The purpose of this study was to examine the remineralizing potential of different toothpaste formulations: toothpastes containing bioactive glass, hydroxyapatite, or strontium acetate with fluoride, when applied to demineralized enamel. Results obtained by scanning electron microscopy (SEM) and SEM/energy dispersive X-ray analyses proved that the hydroxyapatite and bioactive glass-containing toothpastes were highly efficient in promoting enamel remineralization by formation of deposits and a protective layer on the surface of the demineralized enamel, whereas the toothpaste containing 8% strontium acetate and 1040 ppm fluoride as NaF had little, if any, remineralization potential. In conclusion, the treatment of demineralized teeth with toothpastes containing hydroxyapatite or bioactive glass resulted in repair of the damaged tissue. PMID:23659606

Gjorgievska, Elizabeta S; Nicholson, John W; Slipper, Ian J; Stevanovic, Marija M

2013-05-09

141

X-ray fluorescence analysis major elements in silicate minerals  

SciTech Connect

An automated wavelength-dispersive x-ray fluorescence spectrometer is operational for analysis of major elements in rocks and minerals. Procedures for trace-element analysis are being developed. Sample preparation methods and analytical techniques are similar to those commonly used elsewhere, but data reduction is conducted by the Fundamental Parameters program developed by Criss. Unlike empirically derived calibration curves, this data reduction method considers x-ray absorption and secondary fluorescence, which vary with differences in sample composition. X-ray intensities for each element from several standards are averaged to develop a theoretical standard for comparison with samples of unknown composition. Accurate data for samples with wide compositional ranges result from these data reduction and standardization techniques.

Hagan, R.C.

1982-09-01

142

Theoretical Investigation of the Influence of the Electron Distribution Function on X-ray Spectra  

Microsoft Academic Search

Hot electrons play an important role in the radiation kinetics of many HED plasmas, including plasmas driven by high currents or ultrashort laser pulses. The University of Nevada, Reno, has developed time-dependent K- and L-shell kinetics models to diagnose electron distribution functions in such plasmas by analysis of their x-ray spectra. We present the effects of various EDFs on plasma

S. B. Hansen; A. S. Shlyaptseva

2002-01-01

143

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

National Technical Information Service (NTIS)

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...

D. F. Blake

1999-01-01

144

REMOTE X-RAY DIFFRACTION AND X-RAY FLUORESCENCE ANALYSIS ON PLANETARY SURFACES  

Microsoft Academic Search

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

David F. Blake

145

THE DERIVATION OF APPROXIMATE X-RAY SPECTRAL DISTRIBUTIONS AND AN ANALYSIS OF X-RAY \\  

Microsoft Academic Search

Methods of deriving and specifying approximate methods of x-ray spectral ; distribution if either the time or facilities are not available for obtaining ; complete spectra are discussed and compared. Tables are provided that simplify ; the representation of an x-ray beam by three monoenergetic components when the ; transmission curve of the radiation in a suitable absorber is known.

J. R. Greening

1963-01-01

146

X-Ray Free Electron Laser Interaction With Matter  

SciTech Connect

X-ray free electron lasers (XFELs) will enable studying new areas of laser-matter interaction. We summarize the current understanding of the interaction of XFEL pulses with matter and describe some of the simulation approaches that are used to design experiments on future XFEL sources. Modified versions of these models have been successful in guiding and analyzing experiments performed at the extreme-ultraviolet FEL FLASH at wavelengths of 6 nm and longer. For photon energies of several keV, no XFEL-matter interaction experiments have been performed yet but data is anticipated to become available in the near future, which will allow to test our understanding of the interaction physics in this wavelength regime.

Hau-Riege, Stefan [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94550 (United States)

2009-09-10

147

Interactions of clusters with X-ray free electron laser  

NASA Astrophysics Data System (ADS)

In order to investigate the damage of a single bio-molecule when it is irradiated by a strong X-ray free electron laser (XFEL) pulse, time evolution of a single carbon cluster with diameter of 30 nm irradiated with 10-fs XFEL pulse is studied by using particle-in-cell (PIC) code including field-ionization and collisional ionization. The cluster is ionized up to C^4+ within a femtosecond from the surface by strong sheath fields (˜TV/m). Then, the cluster is gradually ionized to higher charge states by collisional ionization. Target size and XFEL pulse intensity have an effect on ionization processes due to the change of sheath field intensity. This result indicates that the field ionization by strong sheath field plays an important role to the damage of a single bio-molecule.

Fukuda, Yuji; Nakamura, Tatsufumi; Moribayashi, Kengo; Kishimoto, Yasuaki

2008-11-01

148

Focusing mirror for x-ray free-electron lasers  

SciTech Connect

We present the design, fabrication, and evaluation of a large total-reflection mirror for focusing x-ray free-electron laser beams to nanometer dimensions. We used an elliptical focusing mirror made of silicon that was 400 mm long and had a focal length of 550 mm. Electrolytic in-process dressing grinding was used for initial-step figuring and elastic emission machining was employed for final figuring and surface smoothing. A figure accuracy with a peak-to-valley height of 2 nm was achieved across the entire area. Characterization of the focused beam was performed at BL29XUL of SPring-8. The focused beam size was 75 nm at 15 keV, which is almost equal to the theoretical size.

Mimura, Hidekazu; Kimura, Takashi; Yamakawa, Daisuke; Matsuyama, Satoshi [Department of Precision Science and Technology, Research Center for Ultra-Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Morita, Shinya; Uehara, Yoshihiro; Ohmori, Hitoshi [RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Lin, Weimin [Faculty of Systems Science and Technology, Department of Machine Intelligence and Systems Engineering, Akita Prefectural University, 84-4 Tsuchiya-Ebinokuchi Yurihonjo, Akita 015-0055 (Japan); Yumoto, Hirokatsu; Ohashi, Haruhiko [Japan Synchrotron Radiation Research Institute (JASRI)/SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Tamasaku, Kenji; Nishino, Yoshinori; Yabashi, Makina; Ishikawa, Tetsuya [RIKEN/SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Yamauchi, Kazuto [Department of Precision Science and Technology, Research Center for Ultra-Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Research Center for Ultra-Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan)

2008-08-15

149

Focusing mirror for x-ray free-electron lasers  

NASA Astrophysics Data System (ADS)

We present the design, fabrication, and evaluation of a large total-reflection mirror for focusing x-ray free-electron laser beams to nanometer dimensions. We used an elliptical focusing mirror made of silicon that was 400 mm long and had a focal length of 550 mm. Electrolytic in-process dressing grinding was used for initial-step figuring and elastic emission machining was employed for final figuring and surface smoothing. A figure accuracy with a peak-to-valley height of 2 nm was achieved across the entire area. Characterization of the focused beam was performed at BL29XUL of SPring-8. The focused beam size was 75 nm at 15 keV, which is almost equal to the theoretical size.

Mimura, Hidekazu; Morita, Shinya; Kimura, Takashi; Yamakawa, Daisuke; Lin, Weimin; Uehara, Yoshihiro; Matsuyama, Satoshi; Yumoto, Hirokatsu; Ohashi, Haruhiko; Tamasaku, Kenji; Nishino, Yoshinori; Yabashi, Makina; Ishikawa, Tetsuya; Ohmori, Hitoshi; Yamauchi, Kazuto

2008-08-01

150

Focusing mirror for x-ray free-electron lasers.  

PubMed

We present the design, fabrication, and evaluation of a large total-reflection mirror for focusing x-ray free-electron laser beams to nanometer dimensions. We used an elliptical focusing mirror made of silicon that was 400 mm long and had a focal length of 550 mm. Electrolytic in-process dressing grinding was used for initial-step figuring and elastic emission machining was employed for final figuring and surface smoothing. A figure accuracy with a peak-to-valley height of 2 nm was achieved across the entire area. Characterization of the focused beam was performed at BL29XUL of SPring-8. The focused beam size was 75 nm at 15 keV, which is almost equal to the theoretical size. PMID:19044333

Mimura, Hidekazu; Morita, Shinya; Kimura, Takashi; Yamakawa, Daisuke; Lin, Weimin; Uehara, Yoshihiro; Matsuyama, Satoshi; Yumoto, Hirokatsu; Ohashi, Haruhiko; Tamasaku, Kenji; Nishino, Yoshinori; Yabashi, Makina; Ishikawa, Tetsuya; Ohmori, Hitoshi; Yamauchi, Kazuto

2008-08-01

151

MESSENGER detection of electron-induced X-ray fluorescence from Mercury's surface  

NASA Astrophysics Data System (ADS)

The X-Ray Spectrometer (XRS) on the MESSENGER spacecraft measures elemental abundances on the surface of Mercury by detecting fluorescent X-ray emissions induced on the planet's surface by the incident solar X-ray flux. The XRS began orbital observations on 23 March 2011 and has observed X-ray fluorescence (XRF) from the surface of the planet whenever a sunlit portion of Mercury has been within the XRS field of view. Solar flares are generally required to provide sufficient signal to detect elements that fluoresce at energies above ˜2 keV, but XRF up to the calcium 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. Many such events have been detected and are identified as electron-induced X-ray emission produced by the interaction of ˜1-10 keV electrons with Mercury's surface. Electrons in this energy range were detected by the XRS during the three Mercury flybys and have also been observed regularly in orbit about Mercury. Knowledge of the energy spectrum of the electrons precipitating at the planet's surface makes it possible to infer surface composition from the measured fluorescent spectra, providing additional measurement opportunities for the XRS. Abundance results for Mg, Al, and Si are in good agreement with those derived from solar-induced XRF data, providing independent validation of the analysis methodologies. Derived S and Ca abundances are somewhat higher than derived from the solar-induced fluorescence data, possibly reflecting incomplete knowledge of the energy spectra of electrons impacting the planet.

Starr, Richard D.; Schriver, David; Nittler, Larry R.; Weider, Shoshana Z.; Byrne, Paul K.; Ho, George C.; Rhodes, Edgar A.; Schlemm, Charles E., II; Solomon, Sean C.; Trávní?ek, Pavel M.

2012-08-01

152

X-ray and electron spectroscopy investigation of the core–shell nanowires of ZnO:Mn  

Microsoft Academic Search

ZnO\\/ZnO:Mn core–shell nanowires were studied by means of X-ray absorption spectroscopy of the Mn K- and L2,3-edges and electron energy loss spectroscopy of the O K-edge. The combination of conventional X-ray and nanofocused electron spectroscopies together with advanced theoretical analysis turned out to be fruitful for the clear identification of the Mn phase in the volume of the core–shell structures.

A. A. Guda; N. Smolentsev; J. Verbeeck; E. M. Kaidashev; Y. Zubavichus; A. N. Kravtsova; O. E. Polozhentsev; A. V. Soldatov

2011-01-01

153

Dynamical x-ray diffraction from nonuniform crystalline films: Application to x-ray rocking curve analysis  

Microsoft Academic Search

A dynamical model for the general case of Bragg x-ray diffraction from arbitrarily thick nonuniform crystalline films is presented. The model incorporates depth-dependent strain and a spherically symmetric Gaussian distribution of randomly displaced atoms and can be applied to the rocking curve analysis of ion-damaged single crystals and strained layer superlattices. The analysis of x-ray rocking curves using this model

C. R. Wie; T. A. Tombrello; T. Vreeland Jr.

1986-01-01

154

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.

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; Uhlen, Fredrik; Vogt, Ulrich; Hertz, Hans M.; Schroer, Christian G.

2013-01-01

155

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

NASA Astrophysics Data System (ADS)

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.

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.

2013-04-01

156

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

157

X-RAY EMISSION ANALYSIS: SAMPLE LOSSES DURING EXCITATION  

EPA Science Inventory

Many samples of atmospheric aerosols and biological materials containing volatile or unstable species are now being examined by X-ray emission analysis, and loss of these species by sample heating is a critical consideration. The amount of heat energy deposited in a sample by the...

158

X-Ray structure analysis of procyanidin B1  

Microsoft Academic Search

Dimeric procyanidins are widespread in fruits. Their physiological effect as antioxidants is of importance. Since they possess five stereogenic centers they occur in diastereomeric forms. The biogenesis is discussed. The constitution and configuration of procyanidin B1 is proved by X-ray structure analysis of its decaacetyl derivative.

Klaus Weinges; Hartmut Schick; Frank Rominger

2001-01-01

159

Dynamical x-ray diffraction from nonuniform crystalline films: Application to x-ray rocking curve analysis  

SciTech Connect

A dynamical model for the general case of Bragg x-ray diffraction from arbitrarily thick nonuniform crystalline films is presented. The model incorporates depth-dependent strain and a spherically symmetric Gaussian distribution of randomly displaced atoms and can be applied to the rocking curve analysis of ion-damaged single crystals and strained layer superlattices. The analysis of x-ray rocking curves using this model provides detailed strain and damage depth distributions for ion-implanted or MeV-ion-bombarded crystals and layer thickness, and lattice strain distributions for epitaxial layers and superlattices. The computation time using the dynamical model is comparable to that using a kinematical model. We also present detailed strain and damage depth distributions in MeV-ion-bombarded GaAs(100) crystals. The perpendicular strain at the sample surface, measured as a function of ion-beam dose (D), nuclear stopping power (S/sub n/), and electronic stopping power (S/sub e/) is shown to vary according to (1-kS/sub e/)DS/sub n/ and saturate at high doses.

Wie, C.R.; Tombrello, T.A.; Vreeland T. Jr.

1986-06-01

160

The First Direct Measurement of an Early B Supergiant X-ray Source Electron Density  

NASA Astrophysics Data System (ADS)

The ratio of the He-like ion forbidden to intercombination emission lines (f/i) provides a diagnostic for determining either the electron density of an X-ray source (collisional-dominated), or the X-ray source spatial location relative to a central EUV/UV radiation source (radiation-dominated). With the advent of high energy resolution spectroscopy, this diagnostic has become a well proven technique for determining the radial distribution of X-ray sources in OB stellar winds. However, in high energy ions (e.g., Si XIII) where the strength of this ratio is controlled by the radiation shortward of the Lyman edge, we show that there is an expected transition from radiation-dominance to collisional-dominance in the early B star spectral range. Because the photospheric flux is weak in the spectral energy region controlling the Si XIII f/i line ratio, we can probe stellar wind distributed X-ray source models from a different perspective and address fundamental issues pertaining to the origin of OB stellar X-ray emission. To verify this behavior we obtained four Chandra HETGS observations of the early B supergiant ? Ori (B0.5Ia) over a time span of approximately 10 days (total exposure = 234 ks). These observations allow us to explore the expected transition to collisional dominance. But, more importantly, our analysis of the Si XIII f/i line ratio has revealed the first direct measurement of an X-ray source density ( 1013 cm-3). We discuss the implications of these results.

Waldron, Wayne L.; Cassinelli, J. P.; Miller, N. A.; Schlegel, E. M.

2012-01-01

161

Electron Paramagnetic Resonance studies of x-ray irradiated Nafion  

NASA Astrophysics Data System (ADS)

Fuel cells promise a bright future as power sources for a variety of electronic equipment as well as more power demanding elements. Nafion (DuPont's trademark of a sulfonated tetrafluorethylene polymer modified from Teflon) is the heart of Proton Exchange Membrane Fuel Cells (PEMFCs) as well as Direct Methanol Fuel Cells (DMFCs). Fuel cells are used to power electronic equipment on spacecraft, satellites and unpiloted high altitude aircraft, where ionizing radiation can be a concern. Electron Paramagnetic Resonance (EPR) is a spectroscopic technique that is very sensitive to free radicals such as those produced by ionizing radiation therefore EPR can give us a window into the degradation of the Nafion membranes due to the ionizing radiation. Nafion samples were irradiated using a x-ray diffractometer with a copper target operating at 40kV and 55mA for at least 3hrs. X-Band EPR spectroscopy of the irradiated nafion reveals a peak at 3400G with a width of 10G, which decays over time, completely diminishing in a couple of weeks. Preliminary results from the polarization studies on the effects of ionizing radiation will also be presented.

Fragoso, Juan; Usher, Timothy

2007-03-01

162

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

163

Controlled dispersion parallel wavelength x-ray spectrometer for electron microscopy.  

National Technical Information Service (NTIS)

This paper describes a new technique for the detection of x-rays in electron column instruments used in microanalysis. In electron column instruments, the point source of x-rays is produced by the interaction of a focused electron beam with the sample. Ne...

C. E. Fiori S. A. Wight A. D. Romig

1991-01-01

164

Steps towards x-ray sources based on linac-driven free-electron lasers  

Microsoft Academic Search

X-rays play a crucial role in the study of structural and electronic properties of matter on an atomic scale. With high-brilliance x-ray sources high resolution imaging and the observation of very fast chemical processes become possible. A high-brilliance x-ray free-electron laser (FEL) based on linear accelerator technology using the principle of self-amplified spontaneous emission (SASE) appears to be the most

P. Castro

2003-01-01

165

Electron optics simulation for designing carbon nanotube based field emission x-ray source  

Microsoft Academic Search

In this dissertation, electron optics simulation for designing carbon nanotube (CNT) based field emission x-ray source for medical imaging applications will be presented. However, for design optimization of x-ray tubes accurate electron beam optics simulation is essential. To facilitate design of CNT x-ray sources a commercial 3D finite element software has been chosen for extensive simulation. The results show that

Shabana Sultana

2010-01-01

166

Runaway electron energy measurement using hard x-ray spectroscopy in ``Damavand'' tokamak  

Microsoft Academic Search

Set of experiments has been developed to study existing runaway electrons in ``Damavand'' tokamak plasma upon characteristics of hard x-ray emissions produced by collision of the runaway electrons with the plasma particles and limiters. As a first step, spatial distribution of hard x-ray emissions on the equatorial plane of the torus was considered. Obtained spectra of hard x-ray emissions for

C. Rasouli; D. Iraji; A. H. Farahbod; K. Akhtari; H. Rasouli; H. Modarresi; M. Lamehi

2009-01-01

167

Laser-plasma electron-density measurement using x-ray interferometry  

NASA Astrophysics Data System (ADS)

In this paper, the propagation of x-rays in laser-produced plasma is studied both analytically and numerically. The coupling relation between phase and amplitude of x-rays is derived, the solutions with higher-order corrections are given where the higher-order electron-density gradients have been taken into account. An important parameter ? was introduced, which is related to the errors of the electron-density measurement using x-ray interferometry. It is justified that so long as ?<1, the x-ray interferometry can be used for the measurement of electron density and for greater value of ?, higher-order modifications are needed.

Fu, Xiquan; Guo, Hong

2002-06-01

168

Femtosecond synchronism of x-rays and visible/infrared light in an x-ray free-electron laser  

SciTech Connect

A way is proposed to obtain ultrashort pulses of intense infrared/visible light in few-femtosecond synchronism with x-rays from an x-ray free-electron laser (XFEL). It makes use of the recently proposed emittance-slicing technique [Emma et al., Phys. Rev. Lett. 92, 074801 (2004)] to both restrict the duration of self-amplified spontaneous emission (SASE) to a few femtoseconds and to lead to a coherence enhancement of near-infrared transition undulator radiation (CTUR). The x-rays and the near-infrared light originate within the XFEL undulator from the same slice of electrons within a bunch and are therefore perfectly synchronized with each other. An example of realizing the scheme at the Linac Coherent Light Source is presented. A few side issues are explored briefly, such as the magnitude of the velocity term versus the acceleration term in the Lienard-Wiechert fields and the possible use of the CTUR as a diagnostic tool for the SASE process itself.

Adams, B. W. [Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2007-12-15

169

Electronic structure and muonic x-ray intensities in isoelectronic series of neon and argon  

Microsoft Academic Search

We report on muonic Lyman-series x-ray intensities measured in gaseous argon and in K+, Cl-, Na+, and F- in the compounds KF and NaCl. The analysis of their structures, including neon, shows that both the spatial symmetry and the binding energy of the electrons of outer shells determine the angular momentum distribution of captured muons. The conclusions are in agreement

R. Jacot-Guillarmod; F. Bienz; M. Boschung; C. Piller; L. A. Schaller; L. Schellenberg; H. Schneuwly; D. Siradovic

1988-01-01

170

Electronic structure and muonic x-ray intensities in isoelectronic series of neon and argon  

NASA Astrophysics Data System (ADS)

We report on muonic Lyman-series x-ray intensities measured in gaseous argon and in K+, Cl-, Na+, and F- in the compounds KF and NaCl. The analysis of their structures, including neon, shows that both the spatial symmetry and the binding energy of the electrons of outer shells determine the angular momentum distribution of captured muons. The conclusions are in agreement with the modified model of ``large mesic molecules.''

Jacot-Guillarmod, R.; Bienz, F.; Boschung, M.; Piller, C.; Schaller, L. A.; Schellenberg, L.; Schneuwly, H.; Siradovic, D.

1988-05-01

171

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

172

Electron velocity distributions measured with soft x-ray PHA at RTP  

Microsoft Academic Search

A soft x-ray pulse height analysis (PHA) system is begin used at the Rijhuizen Tokamak Project to study the electron velocity distribution. A liquid nitrogen cooled Si(Li) detector is used to view the plasma along a tangential line of sight. A gas cell in combination with Al foils is used for filtering. The data-acquisition system is set up in such

D. F. da Cruz; J. H. Meijer; A. J. H. Donne´

1992-01-01

173

Characterization of Nonmelted Particles and Molten Splats in Plasma-Sprayed Al2O3 Coatings by a Combination of Scanning Electron Microscopy, X-ray Diffraction Analysis, and Confocal Raman Analysis  

NASA Astrophysics Data System (ADS)

Plasma-sprayed ceramic coatings are deposited by flattened splats together with some nonmelted particles. In this study, both nonmelted particles and molten splats in plasma-sprayed alumina coatings were examined by a combination of scanning electron microscopy, x-ray diffraction analysis, and confocal Raman analysis to aim at the comprehensive understanding and quantitative evaluation of coating microstructure. Results showed that the nonmelted particles can be clearly identified from the polished cross section due to the raised pattern morphology (with convexes) resulting from the higher hardness of the nonmelted particles than molten splats. Raman analysis revealed that there was little ?-Al2O3 phase in the flattened splat region, which confirmed that ?-Al2O3 phase in the coating originated only from nonmelted particles. Moreover, it is proposed that attention should be paid to the weak bonding of the nonmelted particles to surrounding flattened splats during the preparation of samples for the quantitative characterization of coating microstructure.

Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

2013-03-01

174

Image analysis and X-ray microanalysis in cytochemistry  

SciTech Connect

When cytochemical reaction products are homogeneously distributed within an organelle, point analyses suffice for the quantitative approach. However, quantitative analysis becomes tedious, when the elements in the reaction product are inhomogeneously distributed. Problems arise when elements from two reaction products have to be related to each other, or to endogenous cytological products (ferritin, haemosiderin, calcium, electron dense markers), either topographically or in concentration. When analyzing inhomogeneous/heteromorphical reaction product-containing organelles special attention has to be paid to measure and relate both volume and concentration. In this paper a relative simple structure (eosinophil granules) is chosen to demonstrate that the acquisition of the requested morphometrical plus chemical information and their integration is possible. The following points will be covered to acquire the morphometrical and chemical information: a). How to estimate the total cell cross-sectioned area. b). How to estimate the total cross-sectioned area of all reaction product-containing particles inside that cell. The ratio of these two areas will provide the requested information about the particle volume fraction. By using the X-ray detector in addition: c). How to acquire the chemical information at the requested resolution, within a reasonable total acquisition time d). How to integrate the morphometrical and chemical data per organelle, by matrix analysis in a reduced scan area. e). How to acquire quantitative chemical information, by the use of cross-sectioned standards. f). How to make this acquisition method independent from changes in the instrumental conditions during the acquisition.

de Bruijn, W.C.; Koerten, H.K.; Cleton-Soeteman, M.I.; Blok-van Hoek, C.J.

1987-12-01

175

Coherence Properties of Individual Femtosecond Pulses of an X-ray Free-Electron Laser  

SciTech Connect

Measurements of the spatial and temporal coherence of single, femtosecond x-ray pulses generated by the first hard x-ray free-electron laser, the Linac Coherent Light Source, are presented. Single-shot measurements were performed at 780 eV x-ray photon energy using apertures containing double pinholes in 'diffract-and-destroy' mode. We determined a coherence length of 17 {micro}m in the vertical direction, which is approximately the size of the focused Linac Coherent Light Source beam in the same direction. The analysis of the diffraction patterns produced by the pinholes with the largest separation yields an estimate of the temporal coherence time of 0.55 fs. We find that the total degree of transverse coherence is 56% and that the x-ray pulses are adequately described by two transverse coherent modes in each direction. This leads us to the conclusion that 78% of the total power is contained in the dominant mode.

Vartanyants, I.A.; /DESY /Moscow Phys. Eng. Inst.; Singer, A.; Mancuso, A.P.; Yefanov, O.M.; /DESY; Sakdinawat, A.; Liu, Y.; Bang, E.; /UC, Berkeley; Williams, G.J.; /SLAC; Cadenazzi, G.; Abbey, B.; /Melbourne U.; Sinn, H.; /European XFEL, Hamburg; Attwood, D.; /UC, Berkeley; Nugent, K.A.; /Melbourne U.; Weckert, E.; /DESY; Wang, T.; Zhu, D.; Wu, B.; Graves, C.; Scherz, A.; Turner, J.J.; Schlotter, W.F.; /SLAC /LERMA, Ivry /Zurich, ETH /LBL, Berkeley /ANL, APS /Argonne /SLAC /LLNL, Livermore /Latrobe U. /SLAC /SLAC /European XFEL, Hamburg /SLAC /Hamburg U.

2012-06-06

176

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

177

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

178

X-ray cross correlation analysis uncovers hidden local symmetries in disordered matter  

PubMed Central

We explore the different local symmetries in colloidal glasses beyond the standard pair correlation analysis. Using our newly developed X-ray cross correlation analysis (XCCA) concept together with brilliant coherent X-ray sources, we have been able to access and classify the otherwise hidden local order within disorder. The emerging local symmetries are coupled to distinct momentum transfer (Q) values, which do not coincide with the maxima of the amorphous structure factor. Four-, 6-, 10- and, most prevalently, 5-fold symmetries are observed. The observation of dynamical evolution of these symmetries forms a connection to dynamical heterogeneities in glasses, which is far beyond conventional diffraction analysis. The XCCA concept opens up a fascinating view into the world of disorder and will definitely allow, with the advent of free electron X-ray lasers, an accurate and systematic experimental characterization of the structure of the liquid and glass states.

Wochner, Peter; Gutt, Christian; Autenrieth, Tina; Demmer, Thomas; Bugaev, Volodymyr; Ortiz, Alejandro Diaz; Duri, Agnes; Zontone, Federico; Grubel, Gerhard; Dosch, Helmut

2009-01-01

179

Chemical selective microstructural analysis of thin film using resonant x-ray reflectivity  

NASA Astrophysics Data System (ADS)

Strong modulations of the reflected x-ray intensities near the respective absorption edges of the constituent materials promise to determine layer composition of thin film structures along with spectroscopic like information. Near the absorption edge, the orders of magnitude more contrast beyond the pure electron density distributions of materials find an approach to overcome the low density difficulty of the conventional x-ray reflectivity technique. These aspects are explained by experimental studies on partially decomposed boron nitride thin films. Chemical composition profile is determined from free surface to the embedded buried layer with depth resolution in nanometer scale. The results of resonant reflectivity for chemical analysis are correlated with depth dependent x-ray photo electron spectroscopy.

Nayak, Maheswar; Lodha, G. S.

2013-07-01

180

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

2012-08-09

181

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

182

The vacuum system of the European X-ray free electron laser XFEL  

Microsoft Academic Search

The European X-ray Free Electron Laser XFEL, a new international research facility, will be built at DESY\\/Hamburg. The XFEL will generate extremely brilliant and ultra short pulses of spatially coherent X-rays with tuneable wavelengths down to 0.1 nm, and exploit them for revolutionary scientific experiments at various disciplines. The basic process adopted to produce the X-ray pulses is SASE (Self-Amplified

K. Zapfe; M. Böhnert; O. Hensler; D. Hoppe; N. Mildner; B. Nagorny; K. Rehlich; H. Remde; A. Wagner; T. Wohlenberg; J. Wojtkiewicz

2008-01-01

183

X-ray analysis of zinc-copper alloys  

Microsoft Academic Search

Alloys containing up to 38 per cent. zinc constituting the ? brasses are found to possess a face centred cubic lattice, the parameter increasing from 3.608 Å for pure copper to 3.696 Å for an alloy containing 38 per cent. zinc. Solution takes place by the substitution of zinc atoms for copper atoms.(a) The X-ray analysis of a brass containing

E A Owen; G D Preston

1923-01-01

184

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

185

X-ray reflectivity analysis of Pt\\/Co multilayered films  

Microsoft Academic Search

Pt\\/Co multilayered films were prepared by DC sputtering and electron beam evaporation and grazing angle X-ray reflectivity analysis was used to determine the film structure. It was found that the interfaces of the evaporated samples became flatter and more obscure when the substrate temperature rose. The sputtered samples had relatively flat interfaces and the atoms were more closely packed than

Zhihong Jiang; Chang-Lin Kuo; Rongfa Guo; Defang Shen; Tian-Shen Shi

1994-01-01

186

Laser-electron storage ring as a compact source of high-intensity X-rays  

SciTech Connect

The authors propose a laser-electron storage ring as a high-intensity x-ray source. In this compact device, an intense pulse from a high power laser, stored in a highly reflective optical resonator, repetitively Compton backscatters off a bunched electron beam that circulates in a compact storage ring. The laser-electron interaction not only gives rise to x-rays at the desired wavelength, but also stabilizes the dense electron bunch against the intrabeam scattering effect in the storage ring. Thus, a sufficient amount of x-rays can be generated by this device to make it an excellent and flexible x-ray source for high-throughput x-ray lithography and many other applications.

Huang, Z.; Ruth, R.D.

1997-10-01

187

X-ray texture analysis of paper coating pigments and the correlation with chemical composition analysis  

NASA Astrophysics Data System (ADS)

The present research experiments the applicability of x-ray texture analysis in investigating the properties of paper coatings. The preferred orientations of kaolin, talc, ground calcium carbonate, and precipitated calcium carbonate particles used in four different paper coatings were determined qualitatively based on the measured crystal orientation data. The extent of the orientation, namely, the degree of the texture of each pigment, was characterized quantitatively using a single parameter. As a result, the effect of paper calendering is clearly seen as an increase on the degree of texture of the coating pigments. The effect of calendering on the preferred orientation of kaolin was also evident in an independent energy dispersive spectrometer analysis on micrometer scale and an electron spectroscopy for chemical analysis on nanometer scale. Thus, the present work proves x-ray texture analysis to be a potential research tool for characterizing the properties of paper coating layers.

Roine, J.; Tenho, M.; Murtomaa, M.; Lehto, V.-P.; Kansanaho, R.

2007-10-01

188

Electron beam requirements for soft x-ray/XUV free-electron lasers  

SciTech Connect

A discussion of the electron beam quality (peak current, energy spread, and transverse emittance) required to drive short-wavelength free-electron lasers in the XUV (10-100 nm) and soft x-ray (<10 nm) optical wavelength ranges is presented.

Goldstein, J.C.

1987-01-01

189

ELECTRON BEAM DIAGNOSTICS WITH TRANSVERSE DEFLECTING STRUCTURES AT THE EUROPEAN X-RAY FREE ELECTRON LASER  

Microsoft Academic Search

The operation of the European X-Ray Free Electron Laser (XFEL) puts stringent demands on the peak cur- rent, transverse slice emittance and slice energy spread of the driving electron beam. For monitoring and stabilizing these parameters, dedicated diagnostic beamlines each in- cluding a horizontally operated transverse deflecting struc- ture (TDS) are planned to be installed. Observation screens downstream of the

M. Rohrs; C. Gerth

190

Three-Dimensional X-ray Observation of Atmospheric Biological Samples by Linear-Array Scanning-Electron Generation X-ray Microscope System  

PubMed Central

Recently, we developed a soft X-ray microscope called the scanning-electron generation X-ray microscope (SGXM), which consists of a simple X-ray detection system that detects X-rays emitted from the interaction between a scanning electron beam (EB) and the thin film of the sample mount. We present herein a three-dimensional (3D) X-ray detection system that is based on the SGXM technology and designed for studying atmospheric biological samples. This 3D X-ray detection system contains a linear X-ray photodiode (PD) array. The specimens are placed under a CuZn-coated Si3N4 thin film, which is attached to an atmospheric sample holder. Multiple tilt X-ray images of the samples are detected simultaneously by the linear array of X-ray PDs, and the 3D structure is calculated by a new 3D reconstruction method that uses a simulated-annealing algorithm. The resulting 3D models clearly reveal the inner structure of the bacterium. In addition, the proposed method can easily be used for diverse samples in a broad range of scientific fields.

Ogura, Toshihiko

2011-01-01

191

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

192

Calculation of x-ray spectra emerging from an x-ray tube. Part I. Electron penetration characteristics in x-ray targets  

SciTech Connect

The penetration characteristics of electron beams into x-ray targets are investigated for incident electron kinetic energies in the range 50-150 keV. The frequency densities of electrons penetrating to a depth x in a target, with a fraction of initial kinetic energy, u, are calculated using Monte Carlo methods for beam energies of 50, 80, 100, 120 and 150 keV in a tungsten target. The frequency densities for 100 keV electrons in Al, Mo and Re targets are also calculated. A mixture of simple modeling with equations and interpolation from data is used to generalize the calculations in tungsten. Where possible, parameters derived from the Monte Carlo data are compared to experimental measurements. Previous electron transport approximations in the semiempirical models of other authors are discussed and related to this work. In particular, the crudity of the use of the Thomson-Whiddington law to describe electron penetration and energy loss is highlighted. The results presented here may be used towards calculating the target self-attenuation correction for bremsstrahlung photons emitted within a tungsten target.

Poludniowski, Gavin G.; Evans, Philip M. [Joint Department of Physics, Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, Downs Road, Sutton, Surrey SM2 5PT (United Kingdom)

2007-06-15

193

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

NASA Astrophysics Data System (ADS)

X-ray 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, a nominal CT image will be collected. 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). Elemental and solid-phase distributions on the exposed surfaces, pre-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 CT data. If necessary, solid-phase and pore-space boundaries will be resolved using X-ray phase-contrast imaging, 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 and tomographic images along a single image plane, and have used standard methods to isolate pore space within the CT 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.; McKinley, J. P.; Miller, E. A.; Liu, J.

2011-12-01

194

Flash X-Ray (FXR) Accelerator Optimization Electronic Time-Resolved Measurement of X-Ray Source Size  

Microsoft Academic Search

Lawrence Livermore National Laboratory (LLNL) is currently investigating various approaches to minimize the x-ray source size on the Flash X-Ray (FXR) linear induction accelerator in order to improve x-ray flux and increase resolution for hydrodynamic radiography experiments. In order to effectively gauge improvements to final x-ray source size, a fast, robust, and accurate system for measuring the spot size is

J Jacob; M Ong; P Wargo

2005-01-01

195

Measurements of Suprathermal Electrons in Hohlraum Plasmas with X-Ray Spectroscopy  

SciTech Connect

Nonthermal excitation of atomic states by suprathermal electrons was observed for the first time within inertial confinement fusion hohlraum plasmas. The nonthermal excitation process results in the simultaneous emission of the Ly-{alpha} transition and the K -shell satellite series (lithiumlike through carbonlike) which were observed on temporally resolved x-ray emission spectra. A quantitative analysis with a time-dependent collisional-radiative non-Maxwellian model shows that these spectra can be used to obtain temporally and spatially resolved measurements of the suprathermal electron fraction in indirectly driven inertial confinement fusion targets. {copyright} {ital 1998} {ital The American Physical Society}

Glenzer, S.H.; Lee, R.W.; Back, C.A.; Estabrook, K.G.; MacGowan, B.J.; Shepard, T.D.; Turner, R.E. [L-399, Lawrence Livermore National Laboratory, University of California, P.O. Box 808, Livermore, California 94551 (United States); Rosmej, F.B. [Institut fuer Experimentalphysik V, Ruhr-Universitaet Bochum, 44780 Bochum (Germany)

1998-07-01

196

The Physics of Radiotherapy X-Rays and Electrons  

Microsoft Academic Search

This book is the updated successor to The Physics of Radiotherapy X-Rays from Linear Accelerators, published in 1997 by three well-respected radiotherapy physicists from Australian centres. Time marches on and so does the subject. The last decade has been a time of rapid and exciting change for radiation oncology and radiotherapy physics and this new book aims to update the

David I Thwaites

2008-01-01

197

X-ray observations and analysis with the Chandra X-ray observatory (abstract)  

Microsoft Academic Search

The Chandra X-ray telescope has four separate detectors, two charge coupled devices, and two microchannel plates, behind a set of four highly polished, nested mirrors. The on-orbit performance of the imaging system is <1 arcsec, a dramatic improvement from the 5-8 arcsec previously available. In addition, two transmission gratings can be placed in the system, which for point sources can

Randall Smith

2001-01-01

198

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

199

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

NASA Astrophysics Data System (ADS)

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 10×10 cm2 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: 10-5 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.

2006-03-01

200

X-ray nonlinear optical processes using a self-amplified spontaneous emission free-electron laser  

SciTech Connect

In contrast to the long-wavelength regime, x-ray nonlinear optical processes are characterized in general by sequential single-photon single-electron interactions. Despite this fact, the sequential absorption of multiple x-ray photons depends on the statistical properties of the radiation field. Treating the x rays generated by a self-amplified spontaneous emission free-electron laser as fully chaotic, a quantum-mechanical analysis of inner-shell two-photon absorption is performed. It is demonstrated that double-core-hole formation via x-ray two-photon absorption is enhanced by chaotic photon statistics. Numerical calculations using rate equations illustrate the impact of field chaoticity on x-ray nonlinear ionization of helium and neon for photon energies near 1 keV. In the case of neon, processes are discussed that involve up to seven photons. Assuming an x-ray coherence time of 2.6 fs, double-core-hole formation in neon is found to be statistically enhanced by about 30% at an intensity of 10{sup 16} W/cm{sup 2}.

Rohringer, Nina; Santra, Robin [Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2007-09-15

201

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

SciTech Connect

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.; Holmes, M.; Messerschmidt, M.; Moeller, S.; Krzywinski, J.; Lee, S.; Coffee, R.; Hays, G. [LCLS, SLAC National Accelerator Laboratory, 2575 Sand Hill Rd., Menlo Park, California 94025 (United States); Heimann, P. [LCLS, SLAC National Accelerator Laboratory, 2575 Sand Hill Rd., Menlo Park, California 94025 (United States); Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Krupin, O. [LCLS, SLAC National Accelerator Laboratory, 2575 Sand Hill Rd., Menlo Park, California 94025 (United States); European XFEL GmbH, Albert-Einstein-Ring 19, 22761 Hamburg (Germany); Soufli, R.; Fernandez-Perea, M.; Hau-Riege, S. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States); Kelez, N. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Beye, M.; Gerken, N.; Sorgenfrei, F.; Wurth, W. [Institute for Experimental Physics and CFEL, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); and others

2012-04-15

202

MTF and DQE analysis of x-ray intensifying screens  

Microsoft Academic Search

The image information transfer properties of a number of x-ray fluorescent screens have been calculated for x-ray energies from 10 to 160 keV. The detective quantum efficiency of the screens at each x-ray energy has been determined by separate calculations of the x-ray absorption efficiency and the statistical factor associated with the emission of light photons upon absorption of an

Yi Wang; Jingjin Wang; Kuilu Wang; Guofu Zhu; Guozhi Liu

1999-01-01

203

Noise analysis for X-ray navigation systems  

Microsoft Academic Search

Much as the Global Positioning System has ushered in an era of autonomous navigation on a global scale, X-ray navigation (XNAV) offers the possibility of autonomous navigation anywhere in the solar system. X-ray astronomers have identified a number of X-ray pulsars whose pulsed emissions have stabilities comparable to atomic clocks. X-ray navigation uses phase measurements from these sources to establish

John Hanson; Suneel Sheikh; Paul Graven; John Collins

2008-01-01

204

EXSAA: Environmentally-Induced X-ray Spectral Analysis Automation  

NASA Astrophysics Data System (ADS)

X-ray fluorescence (XRF) spectrometry is one of the principal means of compositional analysis in the lab and in the field: it will be a central tool in NASA's Exploration Initiative (EI) missions. No currently available XRF software has the generic functionality to provide the basis for XRF experiment design, instrument development, and data interpretation for the suite of prospective EI missions. In response to this need, we have developed EXSAA (Environmentally-induced X-ray Spectral Analysis Automation), a generic, fast, interactive spectral simulation tool which can be used in assessing broadband continuous spectra being generated and detected during reconnaissance missions and field campaigns involving planetary surfaces. The software produces model spectra of detectable environmentally-induced X-ray spectra from fundamental principles for target characteristics and conditions likely to be experienced in remote or in situ planetary missions. Fluorescence is modeled following Jenkins and DeVries (1967); coherent and Compton scattering following Hubbell (1969). The modeling provided is extensible, and a user interface provides for selection of source, detector characteristics, compositional components, and geometry for known targets. An immediate application of the tool is the prediction for mission planning purposes of X-ray flux to be expected for a range of targets and instrumentation. A longer-term application is the model basis for the recovery of surface composition from actual missions, where some parameters (e.g. source flux) will be known, and others obtained from a Bayesian analysis of the observations. Ultimately, EXSAA could function as part of the agent-based SAA Toolkit being developed by a group of physical scientists, systems engineers, and AI practitioners to automate portions of the spectral analysis process. EXSAA could be called on by human or machine agents to provide an understanding of XRF phenomena for tasks including specifically (1) instrument and mission design and planning, or (2) model-based data analysis. Thus EXSAA could support traditional design methods and enable a variety of experiments in automated design and operation. The far term objective is to develop a toolkit for use at the human/robotic interface during exploration of lunar or Martian surfaces.

Fallon, F. W.; Clark, P. E.; Rilee, M. L.; Truszkowski, W.

2005-05-01

205

ACCELERATOR LAYOUT AND PHYSICS OF X-RAY FREE-ELECTRON LASERS  

Microsoft Academic Search

X-ray Free-Electron Lasers facilities are planned or are already under construction around the world. This talk covers the X-Ray Free-Electron Lasers LCLS (SLAC), European XFEL (DESY) and SCSS (Spring8). All aim for self-amplified spontaneous emission (SASE) FEL radiation of approx. 0.1 nm wavelengths. The required excellent electron beam qualities pose challenges to the accelerator physicists. Space charge forces, coherent synchrotron

W. Decking

206

High resolution electron beam lithography on x ray mask substrates. Effects of electron scattering and membrane heating  

Microsoft Academic Search

The requirements of X-ray masks for a 64 megabit storage in electron beam lithography, with regard to resolution power and positioning accuracy were compared with the present state of electron beam systems. Electron scattering behavior in X-ray mask substrates was examined with special emphasis on the quantification of the proximity effect. A Monte Carlo simulation program was developed. The evaluation

Klaus Reimer

1991-01-01

207

The electronic structure of KTaO3: a combined x-ray spectroscopic investigation  

NASA Astrophysics Data System (ADS)

The electronic structure of potassium tantalate (KTaO3) is studied by various spectroscopic techniques, namely x-ray photoelectron spectroscopy (XPS), x-ray emission spectroscopy (XES), and x-ray absorption spectroscopy (XAS). The experiments are compared with theoretical band structure calculations. Excellent agreement between theory and experiment is achieved. XPS and XES reveal that the valence band is dominated by strongly hybridized Ta 5d and O 2p states. Furthermore, we find that the Ta NIII resonant inelastic x-ray spectroscopy (RIXS) spectra consist of three distinct features. For excitation energies close to the Ta 4p absorption threshold an elastic recombination peak and a resonant Raman-like loss feature are present in addition to nonresonant-like x-ray emission. In comparison with band structure calculations we are able to assign the loss feature to charge transfer excitations between occupied Ta 5d and O 2p states and unoccupied Ta 5d states.

Kuepper, K.; Postnikov, A. V.; Moewes, A.; Schneider, B.; Matteucci, M.; Hesse, H.; Neumann, M.

2004-11-01

208

Supershort avalanche electron beams and x-ray in high-pressure nanosecond discharges  

NASA Astrophysics Data System (ADS)

The properties of a supershort avalanche electron beam (S AEB) and X-ray radiation produced using a nanosecond volume discharge are examined. An electron beam of the runaway electrons with amplitude of ~ 50 A has been obtained in air atmospheric pressure. It is reported that S AEB is formed in the angle above 2? sr. Three groups of the runaway electrons are formed in a gas diode under atmospheric air pressure, when nanosecond voltage pulses with amplitude of hundreds of kilovolts are applied. The electron beam has been generated behind a 45 ?m thick AlBe foil in SF6 and Xe under the pressure of 2 arm, and in He under the pressure of about 12 atm. The paper gives the analysis of a generation mechanism of SAEB.

Tarasenko, V. F.; Baksht, E. H.; Kostyrya, I. D.; Lomaev, M. I.; Rybka, D. V.

2008-10-01

209

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

210

Inelastic x-ray scattering as a probe of electronic excitations. Solid and liquid metals.  

National Technical Information Service (NTIS)

Use of inelastic x-ray scattering to study excitations in condensed matter systems is discussed with emphasis on complementarity with inelastic neutron scattering. In particular, studies of electronic excitations in simple metals are detailed. A long stan...

J. P. Hill

1996-01-01

211

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

212

Single-pulse resonant magnetic scattering using a soft x-ray free-electron laser  

SciTech Connect

We report on single-pulse resonant magnetic scattering experiments using soft x-ray pulses generated by the free-electron laser FLASH at DESY. We could record a magnetic diffraction pattern from a Co/Pt multilayer sample at the Co M{sub 2,3} edge with a single 30-fs-long FEL pulse. The analysis of the magnetic small-angle scattering signal for subsequent pulses indicates a threshold energy density below which there is no indication that the magnetic properties of the sample might be altered.

Gutt, C.; Streit-Nierobisch, S.; Stadler, L.-M.; Faeustlin, R. R.; Treusch, R.; Feldhaus, J.; Weckert, E.; Vartanyants, I. A.; Gruebel, G. [Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, D-22607 Hamburg (Germany); Pfau, B.; Guenther, C. M.; Koennecke, R.; Eisebitt, S. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner Platz 1, D-14109 Berlin (Germany); Institut fuer Optik und Atomare Physik, TU Berlin, Hardenbergstr. 36, D-10623 Berlin (Germany); Froemter, R.; Kobs, A.; Stickler, D.; Oepen, H. P. [Institut fuer Angewandte Physik, Jungiusstr. 11, D-20355 Hamburg (Germany); Grunze, M.; Rosenhahn, A. [Angewandte Physikalische Chemie, Universitaet Heidelberg, Im Neuenheimer Feld 253, D-69120 Heidelberg (Germany); Institute of Toxicology and Genetics (ITG), Forschungszentrum Karlsruhe, P.O. Box 3640, D-76021 Karlsruhe (Germany); Wilhein, T. [Institute for X-ray-Optics, RheinAhr-Campus Remagen, FH Koblenz, Suedallee 2, D-53424 Remagen (Germany)

2010-03-01

213

Idiopathic calcinosis of the scrotum: scanning electron microscopic study with X-ray microanalysis.  

PubMed

In a 31-year-old man 12 nodules up to 1 cm in diameter were observed in the scrotum; these had developed over 3 years. Energy-dispersive x-ray analysis of the dermal foci showed a high content of calcium and phosphorus even in nodules smaller than 1 mm in diameter. No increased mineral deposition was observed in the surrounding connective tissue, however. Scanning electron microscopy revealed finely granulated crystals, and cellular remnants giving rise to development of calcified nodules were disclosed. The results support the hypothesis of a degenerative origin of scrotal calcinosis. PMID:2038776

Füzesi, L; Hollweg, G; Lagrange, W; Mittermayer, C

214

Idiopathic calcinosis of the scrotum: Scanning electron microscopic study with x-ray microanalysis  

SciTech Connect

In a 31-year-old man 12 nodules up to 1 cm in diameter were observed in the scrotum; these had developed over 3 years. Energy-dispersive x-ray analysis of the dermal foci showed a high content of calcium and phosphorus even in nodules smaller than 1 mm in diameter. No increased mineral deposition was observed in the surrounding connective tissue, however. Scanning electron microscopy revealed finely granulated crystals, and cellular remnants giving rise to development of calcified nodules were disclosed. The results support the hypothesis of a degenerative origin of scrotal calcinosis.

Fuezesi, L.H.; Hollweg, G.; Lagrange, W.; Mittermayer, C. (Technical Univ., Aachen (West Germany))

1991-03-01

215

Surface roughness analysis of multilayer x-ray optics  

NASA Astrophysics Data System (ADS)

Rigaku Innovative Technologies (RIT) produces x-ray optics based on multilayer mirrors. A multilayer mirror is deposited on a wafer and mounted on a solid backing plate in an elliptical shape to focus x-rays. The wafer surface imperfections, defects from the multilayer deposition, and figure errors induced by the mounting process result in some focal spot widening for the final optics. An AFM is used in the spatial period range 0.1 - 10 microns, and a "ZYGO" interferometric microscope is used in the spatial period range 1 micron - 5 mm, to study these imperfections determining the influence of each technological step on the focal spot quality. AFM analysis shows dramatically different roughness between 1 x 1 micron and 20 x 20 micron field of view on super-polished substrates from some suppliers and only a little difference from others. A smoothing effect of a multilayer coating at spatial periods less than one micron as well as defects in multilayer coatings have been observed with power spectral density analysis. Machining marks on the surface of wafers are clearly seen at ZYGO microscope pictures. Ray-tracing simulations based on the ZYGO data show the focal spot shape changes due to the figure errors introduced at the step of a multilayer coated wafer mounting and only background scattering with no focal spot widening from defects induced at the step of multilayer deposition.

Martynov, Vladimir V.; Platonov, Yuriy Y.

2008-08-01

216

Imaging Electron Trajectories in a Laser-Wakefield Cavity Using Betatron X-Ray Radiation  

SciTech Connect

We demonstrate that betatron x-ray radiation accurately provides direct imaging of electrons trajectories accelerated in laser wakefields. Experimental far field x-ray beam profiles reveal that electrons can follow similar transverse trajectories with typical excursions of 1.5 {mu}m{+-}0.5 {mu}m in the plane of laser polarization and 0.7 {mu}m{+-}0.2 {mu}m in the plane perpendicular.

Kim Ta Phuoc; Corde, Sebastien; Shah, Rahul; Albert, Felicie; Fitour, Romuald; Rousseau, Jean-Philippe; Burgy, Frederic; Mercier, Brigitte; Rousse, Antoine [Laboratoire d'Optique Appliquee, ENSTA, CNRS UMR7639, Ecole Polytechnique, Chemin de la Huniere, 91761 Palaiseau (France)

2006-12-01

217

Ablation of Organic Molecular Solids by Focused Soft X-Ray Free-Electron Laser Radiation  

Microsoft Academic Search

The first soft X-ray free-electron laser has recently been put into operation at DESY in Hamburg. Tunable soft X-ray coherent\\u000a radiation can be generated at the FLASH (Free-electron LASer in Hamburg; formerly known as VUV FEL or TTF2 FEL). In the interaction\\u000a experiments reported here, the laser system provided ~ 25-fs, ~ 10-? J pulses of 32-nm radiation. We irradiated

J. Chalupský; L. Juha; J. Kuba; J. Cihelka; V. Hájková; M. Bergh; R. M. Bionta; C. Caleman; H. Chapman; J. Hajdu; S. Hau-Riege; M. Jurek; S. Koptyaev; J. Krása; A. Krenz-Tronnier; J. Krzywinski; J. Meyer-ter-Vehn; R. Nietubyc; J. B. Pelka; R. Sobierajski; K. Sokolowski-Tinten; N. Stojanovic; K. Tiedtke; S. Toleikis; T. Tschentscher; A. Velyhan; H. Wabnitz; U. Zastrau

218

Ultra fast electron beam X-ray tomography and its application to multiphase flow measurement  

Microsoft Academic Search

An ultra fast electron beam CT scanner is introduced which has been developed for flow measurement applications. Its basic design comprises an electron gun with beam optics and fast electromagnetic deflection system and an ultra fast X-ray detector based on room-temperature semiconductor converters. As in other tomographic imaging modalities radiographic projections are generated by a moving X-ray source, in this

Uwe Hampel; Frank Fischer

2008-01-01

219

Chemical shifts in X-ray and photo-electron spectroscopy: a historical review  

Microsoft Academic Search

A review with historical emphasis is given of the discovery and evaluation of chemical shifts in X-ray and photo-electron spectroscopy. The discovery and interpretation of the shifts in the X-ray spectra in the early 1920s are treated as an introduction and general background. The discovery of the shifts in photo-electron spectra, discovered in the late 1950s, and its interpretation, which

Ingvar Lindgren

2004-01-01

220

Boiling the Vacuum with AN X-Ray Free Electron Laser  

Microsoft Academic Search

X-ray free electron lasers will be constructed in this decade, both at SLAC in the form of the so-called Linac Coherent Light Source as well as at DESY, where the so-called TESLA XFEL laboratory uses techniques developed for the design of the TeV energy superconducting electron-positron linear accelerator TESLA. Such X-ray lasers may allow also for high-field science applications by

A. Ringwald

2004-01-01

221

Single-component chemically amplified resist materials for electron-beam and x-ray lithography  

Microsoft Academic Search

Copolymers of 4-tert-butoxycarbonyloxystyrene (TBS) and sulfur dioxide (SO2) have been found to act as sensitive x-ray ((lambda) equals 14 angstrom) and moderately sensitive electron-beam, single component, chemically amplified, aqueous base soluble positive acting resists. The x-ray and electron-beam response of these materials was a function of copolymer composition, where an increase in the sulfur dioxide content enhanced the resist sensitivity.

Anthony E. Novembre; Woon W. Tai; Janet M. Kometani; James E. Hanson; Omkaram Nalamasu; Gary N. Taylor; Elsa Reichmanis; Larry F. Thompson

1991-01-01

222

Resonant inelastic x-ray scattering spectra for electrons in solids  

Microsoft Academic Search

Resonant inelastic x-ray scattering (RIXS) has recently been a subject of remarkable progress due to the advent of high-brilliance synchrotron radiation sources. The authors present a review of both experimental and theoretical investigations of electrons in solids using this second-order optical process, in which there is coherent absorption and emission of x rays at resonance with electronic excitations. The review

Akio Kotani; Shik Shin

2001-01-01

223

Energy-dispersive X-ray fluorescence analysis with pyrographite crystals and small X-ray tubes  

Microsoft Academic Search

The advantages and peculiarities are described of energy-dispersive X-ray fluorescence analysis with preliminary energy selection\\u000a of the radiation coming from a sample with the help of a cylindrical system of pyrographite crystals. The results of application\\u000a of this method to the analysis of U and transuranium elements in the solutions of spent nuclear fuel reprocessing are presented.\\u000a Minimum detectable concentration

V. V. Berdikov; O. I. Grigor'ev; B. S. Iokhin

1980-01-01

224

Soft X-ray, microwave, and hard X-ray emission from a solar flare - Implications for electron heating and acceleration in current channels  

NASA Astrophysics Data System (ADS)

The soft X-ray, microwave, and hard X-ray emissions from the solar flare of May 14, 1980 are studied. The flare consists of a gradual component in soft X-rays and microwaves and a superposed impulsive burst accompanied by hard X-ray emission. The impulsive phase of the flare appears in the soft X-ray emission as a temperature spike and as an increased rate of energy dissipation into the plasma. A new, spatially and spectrally distinct, microwave component appears during the impulsive burst. The data are interpreted in terms of Joule heating and the electric field acceleration of electrons in one or more current sheets. It is found that all three emissions can be generated with sub-Dreicer electric fields. The soft X-ray emitting plasma can be heated by a single current sheet only if the resistivity in the sheet is well above the classical, collisional resistivity. Conditions are also given for the hard X-ray emission to be from nonthermal electrons with classical resistivity.

Holman, Gordon D.; Kundu, Mukul R.; Kane, Sharad R.

1989-10-01

225

Nanostructure Analysis using Coherent X-ray Diffraction  

NASA Astrophysics Data System (ADS)

X-ray crystallography can routinely determine the atomic structure of crystalline materials. The method can be extended to non-crystalline materials by using coherent X-ray diffraction. In X-ray diffraction microscopy, coherent X-ray diffraction patterns are sampled finely enough to satisfy the oversampling condition for solving the phase problem, and the iterative phase retrieval method is used for the sample image reconstruction. Recently, we succeeded in three-dimensional visualization of an unstained human chromosome by X-ray diffraction microscopy. It is the first hard X-ray tomography for cellular organelles. The reconstructed images revealed the internal axial structure, demonstrating an excellent image-contrast of the method.

Nishino, Yoshinori

226

Electron optics simulation for designing carbon nanotube based field emission x-ray source  

NASA Astrophysics Data System (ADS)

In this dissertation, electron optics simulation for designing carbon nanotube (CNT) based field emission x-ray source for medical imaging applications will be presented. However, for design optimization of x-ray tubes accurate electron beam optics simulation is essential. To facilitate design of CNT x-ray sources a commercial 3D finite element software has been chosen for extensive simulation. The results show that a simplified model of uniform electron field emission from the cathode surface is not sufficient when compared to experimental measurements. This necessitated the development of a refined model to describe a macroscopic field emission CNT cathode for electron beam optics simulations. The model emulates the random distribution of CNTs and the associated variation of local field enhancement factor. The main parameter of the model has been derived empirically from the experimentally measured I-V characteristics of the CNT cathode. Simulation results based on this model agree well with experiments which include measurements of the transmission rate and focus spot size. The model provides a consistent simulation platform for optimization of electron beam optics in CNT x-ray source design. A systematic study of electron beam optics in CNT x-ray tubes led to the development of a new generation of compact x-ray source with multiple pixels. A micro focus field emission x-ray source with a variable focal spot size has been fully characterized and evaluated. It has been built and successfully integrated into micro-CT scanners which are capable of dynamic cardiac imaging of free-breathing small animals with high spatial and temporal resolutions. In addition a spatially distributed high power multi-beam x-ray source has also been designed and integrated into a stationary digital breast tomosynthesis (s-DBT) configuration. This system has the potential to reduce the total scan time to 4 seconds and yield superior image quality in breast imaging.

Sultana, Shabana

227

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

228

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

229

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

230

Capillary Optics Based X-Ray Micro-Imaging Elemental Analysis  

NASA Astrophysics Data System (ADS)

A rapidly developed during the last few years micro-X-ray fluorescence spectrometry (?XRF) is a promising multi-elemental technique for non-destructive analysis. Typically it is rather hard to perform laboratory ?XRF analysis because of the difficulty of producing an original small-size X-ray beam as well as its focusing. Recently developed for X-ray beam focusing polycapillary optics offers laboratory X-ray micro probes. The combination of polycapillary lens and fine-focused micro X-ray tube can provide high intensity radiation flux on a sample that is necessary in order to perform the elemental analysis. In comparison to a pinhole, an optimized "X-ray source-op tics" system can result in radiation density gain of more than 3 orders by the value. The most advanced way to get that result is to use the confocal configuration based on two X-ray lenses, one for the fluorescence excitation and the other for the detection of secondary emission from a sample studied. In case of X-ray capillary microfocusing a ?XRF instrument designed in the confocal scheme allows us to obtain a 3D elemental mapping. In this work we will show preliminary results obtained with our prototype, a portable X-ray microscope for X-ray both imaging and fluorescence analysis; it enables ?XRF elemental mapping simultaneously with X-ray imaging. A prototype of compact XRF spectrometer with a spatial resolution less than 100 ?m has been designed.

Hampai, D.; Dabagov, S. B.; Cappuccio, G.; Longoni, A.; Frizzi, T.; Cibin, G.

2010-04-01

231

Energy-dispersive X-ray analysis of the extracellular cadmium sulfide crystallites of Klebsiella aerogenes  

Microsoft Academic Search

Klebsiella aerogenes forms electron-dense partieles on the cell surface in response to the presence of cadmium ions in the growth medium. These particles ranged from 20 to 200 nm in size, and quantitative energy dispersive X-ray analysis established that they comprise cadmium and sulfur in a 1:1 ratio. This observation leads to the conclusion that the particles are cadmium sulfide

Justin D. Holmes; Peter R. Smith; Richard Evans-Gowing; David J. Richardson; David A. Russell; John R. Sodeau

1995-01-01

232

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

NASA Astrophysics Data System (ADS)

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 ?m diameter liquid-gallium-jet anode to produce an ~10 ?m 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 potential for increasing this brightness by approximately three orders of magnitude, making the source suitable for laboratory-scale x-ray crystallography and hard x-ray microscopy.

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

2008-01-01

233

Application of synchrotron radiation to x-ray fluorescence analysis of trace elements  

SciTech Connect

The development of synchrotron radiation x-ray sources has provided the means to greatly extend the capabilities of x-ray fluorescence analysis for determinations of trace element concentrations. A brief description of synchrotron radiation properties provides a background for a discussion of the improved detection limits compared to existing x-ray fluorescence techniques. Calculated detection limits for x-ray microprobes with micrometer spatial resolutions are described and compared with experimental results beginning to appear from a number of laboratories. The current activities and future plans for a dedicated x-ray microprobe beam line at the National Synchrotron Light Source (NSLS) of Brookhaven National Laboratory are presented.

Gordon, B.M.; Jones, K.W.; Hanson, A.L.

1986-08-01

234

Characterization of Carbonitrided and Oxidized Layers on Low-Carbon Steel by Conversion Electron M?ssbauer Spectrometry, X-Ray Diffractometry, and X-Ray Photoelectron Spectrometry  

Microsoft Academic Search

The structures of low-carbon steel oxidized in an aqueous saline bath at 403 K and a fused salt bath at 673 K after carbonitriding were studied using conversion electron Moessbauer spectrometry (CEMS), x-ray diffractometry (XRD), and x-ray photoelectron spectrometry (XPS). Only a doublet peak caused by poor crystallinity of iron oxyhydroxides (FeOOH) or fine particles of iron oxides such as

K. Kurosawa; H.-L. Li; K. Nomura; Y. Ujihira

1999-01-01

235

Electronic Excitations in Vanadium Oxide Phthalocyanine Studied via Resonant Soft X-ray Emission and Resonant Inelastic X-ray Scattering  

SciTech Connect

The electronic structure of the organic semiconductor vanadium oxide phthalocyanine has been studied using resonant inelastic X-ray scattering and X-ray emission spectroscopy. The vanadyl species in the films is shown to be highly localized, and good agreement between the measurements and a density functional calculation is obtained. Both dipole forbidden V 3d to V 3d*, and O 2p to V 3d* charge transfer transitions are observed, and explained in a local molecular orbital model.

Zhang,Y.; Wang, S.; Learmonth, T.; Plucinski, L.; Matsuura, A.; Bernardis, S.; ODonnell, C.; Downes, J.; Smith, K.

2005-01-01

236

Wavelength-dispersive spectrometer for X-ray microfluorescence analysis at the X-ray microscopy beamline ID21 (ESRF)  

PubMed Central

The development of a wavelength-dispersive spectrometer for microfluorescence analysis at the X-ray Microscopy ID21 beamline of the European Synchrotron Radiation Facility (ESRF) is reported. The spectrometer is based on a polycapillary optic for X-ray fluorescence collection and is operated in a flat-crystal geometry. The design considerations as well as operation characteristics of the spectrometer are presented. The achieved performances, in particular the energy resolution, are compared with the results of Monte Carlo simulations. Further improvement in the energy resolution, down to ?eV range, by employing a double-crystal geometry is examined. Finally, examples of applications requiring both spatial and spectral resolutions are presented.

Szlachetko, J.; Cotte, M.; Morse, J.; Salome, M.; Jagodzinski, P.; Dousse, J.-Cl.; Hoszowska, J.; Kayser, Y.; Susini, J.

2010-01-01

237

Resonant inelastic soft x-ray scattering and electronic structure of LiBC  

Microsoft Academic Search

The electronic structure of LiBC has been studied using soft x-ray fluorescence measurements. Resonant inelastic x-ray scattering (RIXS) spectra were measured with the excitation energy tuned to the boron and carbon K-edges. RIXS spectra show dispersive features, which were assigned to the calculated energy bands using the site-selective quantitative band mapping method based on the concept of k-momentum conservation. It

P. F. Karimov; N. A. Skorikov; E. Z. Kurmaev; L. D. Finkelstein; S. Leitch; J. MacNaughton; A. Moewes; T. Mori

2004-01-01

238

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

239

Analyses of petrified wood by electron, X-ray and optical microprobes  

Microsoft Academic Search

Samples of petrified wood of diVerent origins were analyzed by the use of the electron microprobe, capillary X-ray fluorescence microprobe, synchrotron capillary X-ray microprobe and optical microscope, applied in a microprobe manner. The main attention was given to the investigation of the ring structure of the petrified wood and the comparison of this with the ring structure of the living

Andrzej Kuczumow; Bart Vekemans; Olivier Schalm; Walter Dorrine; Pierre Chevallier; Philippe Dillmann; Chul-Un Ro; Koen Janssens

1999-01-01

240

Development of Free-Electron x-Ray Lasers on the TESLA Test Accelerator (DESY, Germany)  

Microsoft Academic Search

The program for developing free-electron x-ray lasers at TESLA started in 1994. The plan is to use the TESLA test accelerator to develop an x-ray laser with minimum wavelength 0.1–6 nm. The first phase of the project was successfully completed in 2001. At saturation, the laser produces ultrashort 30–100 fsec, gigawatt, radiation pulses. The wavelength can be tuned smoothly over

M. V. Yurkov

2003-01-01

241

Hard X ray survey of energetic electrons from low-Earth orbit  

Microsoft Academic Search

Hard X ray and neutron emissions measured in low-Earth orbit are surveyed to develop a global overview of lightning-related energetic-electron precipitation and acceleration processes. Comparison of geographic intensity maps shows the dominance of enhanced hard X ray intensities measured when the satellite was above the continental United States and above the southern Indian Ocean between Madagascar and Australia. This emission

W. C. Feldman; E. M. D. Symbalisty; R. A. Roussel-Dupré

1996-01-01

242

Hard X ray survey of energetic electrons from low-earth orbit  

Microsoft Academic Search

Hard X ray and neutron emissions measured in low-Earth orbit are surveyed to develop a global overview of lightning-related energetic-electron precipitation and acceleration process. Comparison of geographic intensity maps shows the dominance of enhanced hard X ray intensities measured when the satellite was above the continental United States and above the southern Indian Ocean between Madagascar and Australia. The emission

W. C. Feldman; E. M. D. Symbalisty; R. A. Roussel-Dupre

1996-01-01

243

Fast multichannel electron temperature diagnostic for TFTR using x-ray imaging  

Microsoft Academic Search

The TFTR x-ray imaging system (XIS) is an array of 64-Si surface barrier diodes which image the plasma poloidally. Special absorber foils have been installed to permit measurement of electron temperature Te with <100-?s time resolution along 10–30 chords. The technique uses the ratio of x-ray fluxes transmitted through two different foils, which depend mainly on Te. Simulations show that

J. Kiraly; M. Bitter; S. von Goeler; K. W. Hill; L. C. Johnson; K. McGuire; S. Sesnic; N. R. Sauthoff; F. Tenney; K. M. Young

1985-01-01

244

Progress in rod pinch electron beam diodes as intense x-ray radiography sources  

Microsoft Academic Search

Rod-pinch electron beam diodes were reintroduced at BEAMS'98 as small-diameter intense x-ray sources after a twenty-year hiatus. Much progress has been made recently in both analytical and particle-in-cell numerical modeling of the diode behavior and in obtaining intense x-ray sources for pulsed radiography. Rod-pinch diodes utilize a thin annular cathode surrounding a small-diameter anode rod extending through and beyond the

G. Cooperstein; R. J. Commisso; D. D. Hinshelwood; D. Mosher; P. F. Ottinger; S. J. Stephanakis; J. W. Schumer; S. B. Swanekamp; B. V. Weber; F. C. Young; J. E. Maenchen; P. R. Menge; C. L. Olson; B. V. Oliver; D. V. Rose; D. R. Welch; R. Carlson; D. Oro; D. Fulton; E. Hunt; D. Droemer; W. J. DeHope

2000-01-01

245

Time-resolved imaging using x-ray free electron lasers  

Microsoft Academic Search

The ultra-intense, ultra-short x-ray pulses provided by x-ray free electron laser (XFEL) sources are ideally suited to time-resolved studies of structural dynamics with spatial resolution from nanometre to atomic length scales and a temporal resolution of 10 fs or less. With enough photons in a single pulse to enable single-shot measurements and short enough pulses to freeze atomic motion, researchers

Anton Barty

2010-01-01

246

Comparison of the Effect of X-ray and Electron Beam Irradiation on Some Selected Spices  

Microsoft Academic Search

The effect of irradiation with X-rays and electron beams on the microbiological quality of white pepper, sweet red paprika and nutmeg was examined. Statistical analyses were performed on the data to interpret the results on coliforms, total mesophilic counts and thermophilic spores after irradiation with doses ranging from 0 to 10 kGy at different dose rates, 50 Gy\\/min for X-rays

Sabine Van Calenberg; Gauthier Vanhaelewyn; Oswald Van Cleemput; Freddy Callens; Wim Mondelaers; André Huyghebaert

1998-01-01

247

X-RAY NONLINEAR OPTICAL PROCESSES IN ATOMS USING A SELF-AMPLIFIED SPONTANEOUS EMISSION FREE-ELECTRON LASER  

SciTech Connect

X-ray free electron lasers (xFEL) will open new avenues to the virtually unexplored territory of non-linear interactions of x rays with matter. Initially xFELs will be based on the principle of self-amplified spontaneous emission (SASE). Each SASE pulse consists of a number of coherent intensity spikes of random amplitude, i.e. the process is chaotic and pulses are irreproducible. The coherence time of SASE xFELs will be a few femtoseconds for a photon energy near 1 keV. The importance of coherence properties of light in non-linear optical processes was theoretically discovered in the early 1960s. In this contribution we will illustrate the impact of field chaoticity on x-ray non-linear optical processes on neon for photon energies around 1 keV and intensities up to 10{sup 18} W/cm{sup 2}. Resonant and non-resonant processes are discussed. The first process to be addressed is the formation of a double-core hole in neon by photoionization with x rays above 1.25 keV energy. In contrast to the long-wavelength regime, non-linear optical processes in the x-ray regime are characterized in general by sequential single-photon single-electron interactions. Despite this fact, the sequential absorption of multiple x-ray photons depends on the statistical properties of the radiation field. Treating the x rays generated by a SASE FEL as fully chaotic, a quantum-mechanical analysis of inner-shell two-photon absorption is performed. By solving a system of time-dependent rate equations, we demonstrate that double-core hole formation in neon via x-ray two-photon absorption is enhanced by chaotic photon statistics. At an intensity of 10{sup 16} W/cm{sup 2}, the statistical enhancement is about 30%, much smaller than typical values in the optical regime. The second part of this presentation discusses the resonant Auger effect of atomic neon at the 1s-3p transition (at 867.1 eV). For low X-ray intensity, the excitation process 1s {yields} 3p in Neon can be treated perturbatively. The core-hole excited 1s{sup -1} 3p state is embedded in the continuum and decays via Auger-process on the timescale of approximately 5 fs. Increasing the x-ray intensity above 1.5 x 10{sup 18} W/cm{sup 2}, a peak intensity accessible with xFEL sources in the near future, x-ray induced emission from 3p back to 1s becomes possible, i.e. Rabi oscillations between these two levels can be induced. For the numerical analysis of this process, an effective two-level model, including a description of the resonant Auger decay process, is employed. The observation of x-ray-driven atomic populations dynamics in the time domain is challenging for chaotic xFEL pulses. In addition to requiring single-shot measurements, sub-femtosecond temporal resolution would be needed. The Rabi oscillations will, however, be imprinted on the kinetic energy distribution of the resonant Auger electron (see Fig. 1). Measuring the resonant Auger-electron line profile will provide information on both atomic population dynamics and x-ray pulse properties.

Rohringer, N

2008-08-08

248

Wavelet and R/S analysis of the X-ray flickering of cataclysmic variables  

NASA Astrophysics Data System (ADS)

Context. Recently, wavelets and R/S analysis have been used as statistical tools to characterize the optical flickering of cataclysmic variables. Aims: Here we present the first comprehensive study of the statistical properties of X-ray flickering of cataclysmic variables in order to link them with physical parameters. Methods: We analyzed a sample of 97 X-ray light curves of 75 objects of all classes observed with the XMM-Newton space telescope. By using the wavelets analysis, each light curve has been characterized by two parameters, ? and ?, that describe the energy distribution of flickering on different timescales and the strength at a given timescale, respectively. We also used the R/S analysis to determine the Hurst exponent of each light curve and define their degree of stochastic memory in time. Results: The X-ray flickering is typically composed of long time scale events (1.5 ? ? ? 3), with very similar strengths in all the subtypes of cataclysmic variables (-3 ? ? ? -1.5). The X-ray data are distributed in a much smaller area of the ? - ? parameter space with respect to those obtained with optical light curves. The tendency of the optical flickering in magnetic systems to show higher ? values than the non-magnetic systems is not encountered in the X-rays. The Hurst exponents estimated for all light curves of the sample are larger than those found in the visible, with a peak at 0.82. In particular, we do not obtain values lower than 0.5. The X-ray flickering presents a persistent memory in time, which seems to be stronger in objects containing magnetic white dwarf primaries. Conclusions: The similarity of the X-ray flickering in objects of different classes together with the predominance of a persistent stochastic behavior can be explained in terms of magnetically-driven accretion processes acting in a considerable fraction of the analyzed objects. Table 1 is only available in electronic form at http://www.aanda.org

Anzolin, G.; Tamburini, F.; de Martino, D.; Bianchini, A.

2010-09-01

249

Electron charge distribution of CaAl{sub 2-x}Zn{sub x}: Maximum entropy method combined with Rietveld analysis of high-resolution-synchrotron X-ray powder diffraction data  

SciTech Connect

Using short wavelength X-rays from synchrotron radiation (SPring-8), high-resolution powder diffraction patterns were collected. In order to study both the structural relationship and the mechanism of stability in the CaAl{sub 2-x}Zn{sub x} system, among the Laves phases (MgCu{sub 2} and MgNi{sub 2} type) and KHg{sub 2}-type structures, the charge density distribution of CaAl{sub 2-x}Zn{sub x} as a function of x was obtained from the diffraction data by Rietveld analysis combined with the maximum entropy method (MEM). In the MEM charge density maps overlapping electron densities were clearly observed, especially in the Kagome nets of the Laves phases. In order to clarify the charge redistribution in the system, the deformation charge densities from the densities formed by the constituent free atoms are discussed. In the ternary MgNi{sub 2}-type phase, partial ordering of Al and Zn atoms is observed, a finding that is supported by ab-initio total energy calculations. - Graphical abstract: Using short wavelength X-rays from synchrotron radiation (SPring-8), high-resolution powder diffraction patterns of the Laves (MgCu{sub 2} and MgNi{sub 2} type) and KHg{sub 2}-type phases in the CaAl{sub 2-x}Zn{sub x} system were collected. The charge density distribution in the Laves phases as a function of x was obtained from the diffraction data by Rietveld analysis combined with the maximum entropy method (MEM)

Soederberg, Karin [Arrhenius Laboratory, Department of Physical, Inorganic and Structural Chemistry, Stockholm University, Stockholm 10691 (Sweden); Kubota, Yoshiki [Graduate School of Science, Department of Physical Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Muroyama, Norihiro; Gruener, Daniel [Arrhenius Laboratory, Department of Physical, Inorganic and Structural Chemistry, Stockholm University, Stockholm 10691 (Sweden); Yoshimura, Arisa [Graduate School of Science, Department of Physical Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Terasaki, Osamu [Arrhenius Laboratory, Department of Physical, Inorganic and Structural Chemistry, Stockholm University, Stockholm 10691 (Sweden)], E-mail: terasaki@struc.su.se

2008-08-15

250

Micro X-ray diffraction analysis of thin films using grazing-exit conditions.  

PubMed

An X-ray diffraction technique using a hard X-ray microbeam for thin-film analysis has been developed. To optimize the spatial resolution and the surface sensitivity, the X-ray microbeam strikes the sample surface at a large glancing angle while the diffracted X-ray signal is detected with a small (grazing) exit angle. Kirkpatrick-Baez optics developed at the Photon Factory were used, in combination with a multilayer monochromator, for focusing X-rays. The focused beam size was about 10 x 10 micro m. X-ray diffraction patterns of Pd, Pt and their layered structure were measured. Using a small exit angle, the signal-to-background ratio was improved due to a shallow escape depth. Under the grazing-exit condition, the refraction effect of diffracted X-rays was observed, indicating the possibility of surface sensitivity. PMID:15263691

Noma, T; Iida, A

1998-05-01

251

X-ray Split and Delay System for Soft x-ray Pump/Probe Experiments at the LCLS Free Electron Laser  

NASA Astrophysics Data System (ADS)

We will report on the development of a mirror based x-ray split and delay system (XRSD) for soft x-rays at the Linac Coherent Light Source free electron laser. This device will be used for x-ray pump, x-ray probe experiments in gas-phase as well as solid state using the LCLS femtosecond photon beam. The XRSD system will be positioned after the Kirkpatrick-Baez focusing mirrors, delivering two pulses with a variable delay to the interaction chamber. Delay of 0-100 femtoseconds can be produced with resolution under 100 attoseconds. The energy in each pulse will be measured shot to shot. The XRSD is expected to be ready for user experiments in early 2012.

Murphy, Brendan; Bozek, John; Castagna, Jean-Charles; Berrah, Nora

2011-06-01

252

Influence of Bernstein modes on the efficiency of electron cyclotron resonance x-ray source  

SciTech Connect

The article considers the factors influencing the temperature of hot electron component in an electron cyclotron resonance (ECR) x-ray source. In such sources the electron heating occurs often due to extraordinary electromagnetic wave propagating perpendicularly to the magnetic field. In this case the possibility of the absorption of Bernstein modes is regarded as an additional mechanism of electron heating. The Bernstein modes in an ECR x-ray source can arise due to either linear transformation or parametric instability of external transversal wave. The article briefly reviews also the further experiments which will be carried out to study the influence of Bernstein modes on the increase of hot electron temperature and consequently of x-ray emission.

Andreev, V. V.; Nikitin, G.V.; Savanovich, V.Yu.; Umnov, A.M.; Elizarov, L.I.; Serebrennikov, K.S.; Vostrikova, E.A. [Plasma Physics Laboratory, Peoples Friendship University of Russia, 6 Miklukho-Maklaya Street, 117198 Moscow (Russian Federation); Russian Research Center 'Kurchatov Institute', 1, Kurchatov Square, 123182 Moscow (Russian Federation); Peoples Friendship University of Russia, 6 Miklukho-Maklaya Street, 117198 Moscow (Russian Federation) and Russian Research Center 'Kurchatov Institute', 1, Kurchatov Square, 123182 Moscow (Russian Federation)

2006-03-15

253

Obtaining attosecond X-ray pulses using a self-amplifiedspontaneous emission free electron laser  

SciTech Connect

We describe a technique for the generation of a solitary attosecond X-ray pulse in a free electron laser (FEL), via a process of self-amplified spontaneous emission. In this method, electrons experience an energy modulation upon interacting with laser pulses having a duration of a few cycles within single-period wiggler magnets. Two consecutive modulation sections, followed by compression in a dispersive section, are used to obtain a single, sub-femtosecond spike in the electron peak current. This region of the electron beam experiences an enhanced growth rate for FEL amplification. After propagation through a long undulator,this current spike emits a {approx}250 attosecond X-ray pulse whose intensity dominates the X-ray emission from the rest of the electron bunch.

Zholents, A.A.; Penn, G.

2005-01-07

254

Combined Radio and X-ray Diagnostics of Electron Acceleration Region in the Solar Corona  

NASA Astrophysics Data System (ADS)

Solar flares are believed to accelerate both upward and downward propagating electron beams which can radiate emission at radio and X-ray wavelengths correspondingly. The correlation between X-ray and radio emissions in a well observed solar flare allowed us detailed study of the electron acceleration region properties. We used the Nancey Radioheliograph, Phoenix-2 and RHESSI to infer the type III position, type III starting frequency and spectral index of the HXR emission respectively. Using these datasets, we were able to infer not only the location (the height in the corona), but to estimate the spatial size of the electron acceleration site. Using numerical simulations of the electron transport of the electron beam in the corona plasma to relate X-ray and radio data, we find that the spatial size of 10 Mm at an altitude of 50 Mm above the photosphere are consistent with the observations.

Reid, H.; Vilmer, N.; Kontar, E. P.

2010-12-01

255

Time-resolved structural studies at synchrotrons and X-ray free electron lasers: opportunities and challenges  

PubMed Central

X-ray free electron lasers (XFELs) are potentially revolutionary X-ray sources because of their very short pulse duration, extreme peak brilliance and high spatial coherence, features that distinguish them from today’s synchrotron sources. We review recent time-resolved Laue diffraction and time-resolved wide angle X-ray scattering (WAXS) studies at synchrotron sources, and initial static studies at XFELs. XFELs have the potential to transform the field of time-resolved structural biology, yet many challenges arise in devising and adapting hardware, experimental design and data analysis strategies to exploit their unusual properties. Despite these challenges, we are confident that XFEL sources are poised to shed new light on ultrafast protein reaction dynamics.

Neutze, Richard; Moffat, Keith

2012-01-01

256

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

2013-02-19

257

Analysis of Slurry-Coating Effectiveness of CL20 Using Grazing Incidence X-ray Diffraction  

Microsoft Academic Search

A grazing incidence X-ray diffraction technique was developed to characterize the effectiveness of the coating of the solid particles by the binder in energetic formulations and was used in conjunction with scanning electron microscopy, traditional wide-angle X-ray diffraction, and specific gravity measurements to probe the microstructure of PAX-12 granules. The grazing incidence X-ray technique was applied to granules formed upon

BERTON L. GREENBERG; DILHAN M. KALYON; MELEK EROL; MARK MEZGER; KENNETH LEE; SCOTT LUSK

2003-01-01

258

Soft X Ray Telescope (SXT) focus error analysis  

NASA Astrophysics Data System (ADS)

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

1991-03-01

259

Application of Strong Field Physics Techniques to X-Ray Free Electron Laser Science  

NASA Astrophysics Data System (ADS)

With the commissioning of the Linac Coherent Light Source (LCLS), the first x-ray free electron laser (XFEL) was realized at the Stanford Linear Accelerator Center. This novel device brings an unprecedented parameter set to a diverse community of scientists. The short wavelengths and short pulse durations enable an entire new class of time resolved structural analysis. The imaging capabilities enabled by the machine will lead to many breakthroughs in the fields of biophysics and nano technology. With the new capabilities of the LCLS come many challenges. The understanding required to effectively utilize the XFEL on complex molecular or biological systems goes back to the basic atomic physics of the interaction of light and matter. The parameter set of this machine is as unprecedented as it will be untested. To make informed measurements with the LCLS beam, a set of novel diagnostic techniques will be required. This report outlines major contributions made to the early experimental atomic physics and diagnostic efforts at LCLS. Building on a rich history of techniques used for ultra short optical lasers and atomic physics experimentation, a diagnostic instrument and experimental techniques are developed to make spectral, energy and temporal measurements of the LCLS pulses possible. Expanding on earlier studies of ionization performed on optical lasers and synchrotron sources, new ionization mechanisms such as multiphoton ionization in the x-ray regime are observed. Leveraging the unique combination of hard x-ray photon energy, extremely short pulse duration and high pulse energy, a technique for the time resolved study of ultrafast inner shell electronic relaxation processes is developed and studied for feasibility. The common theme to the efforts described here is the advancement of proven techniques and interesting atomic physics phenomena to the next generation of ultra short pulsed x-ray laser systems. The atomic physics explored here lay the groundwork for the next level of understanding the new experiments to be performed on molecular, biological and condensed phase systems using XFEL light pulses. The application of basic atomic physics established over the past 40 years with optical laser systems to diagnostic techniques suitable for the new properties of XFELs will lend crucial insight into the orchestration of future XFEL experiments.

Roedig, Christoph Antony

260

Combining electron microscopic with x-ray crystallographic structures.  

PubMed

Analgorithm has been developed for placing three-dimensional atomic structures into appropriately scaled cryoelectron microscopy maps. The first stage in this process is to conduct a three-dimensional angular search in which the center of gravity of an X-ray crystallographically determined structure is placed on a selected position in the cryoelectron microscopy map. The quality of the fit is measured by the sum of the density at each atomic position. The second stage is to refine the three angles and three translational parameters for the best (usually 25 to 100) fits. Useful criteria for this refinement include the sum of densities at atomic sites, the lack of atoms in negative or low density, the absence of atomic clashes between symmetry-related positions of the atomic structure, and the distances between identifiable features in the map and their positions on the fitted atomic structure. These refinements generally lead to a convergence of the originally chosen, top scoring fits to just a few (about 3 to 8) acceptable possibilities. Usually, the best remaining fit is clearly superior to any of the others. PMID:12051899

Rossmann, M G; Bernal, R; Pletnev, S V

2001-12-01

261

Runaway electron energy measurement using hard x-ray spectroscopy in 'Damavand' tokamak  

SciTech Connect

Set of experiments has been developed to study existing runaway electrons in ''Damavand'' tokamak plasma upon characteristics of hard x-ray emissions produced by collision of the runaway electrons with the plasma particles and limiters. As a first step, spatial distribution of hard x-ray emissions on the equatorial plane of the torus was considered. Obtained spectra of hard x-ray emissions for different alignments of shielded detector indicate isotropic emissivity in the equatorial plane. This is in agreement with wide angle cone of bremsstrahlung radiations, deduced from the mean value of energy of the runaway electrons. The mean energy was calculated from the slope of the energy spectrum of hard x-ray photons. In the second stage in order to investigate time evolution of energy of the runaway electrons, similar technique were applied to obtain hard x-ray energy in every 3 ms intervals, from the beginning to the end of plasma. The mean energy of the runaway electrons increases during the ramp up phase and reaches its maximum between 3 and 9 ms after plasma formation. Also considering the time dependence of the counted photons in each energy range shows that energetic photons are emitted during the ramp up phase of the plasma current in Damavand tokamak.

Rasouli, C.; Farahbod, A. H.; Rasouli, H.; Lamehi, M. [School of Plasma Physics and Nuclear Fusion, Institute of Nuclear Science and Technology, AEOI, P.O. Box 14155-1339, Tehran (Iran, Islamic Republic of); Iraji, D. [Centre de Recherches en Physique des Plasmas, Association EURATOM-Confederation Suisse, Ecole Polytechnique Federale de Lausanne, CH-1015 (Switzerland); Akhtari, K. [Department of Physics, Sharif University of Technology, P.O. Box 11365-9161, Tehran (Iran, Islamic Republic of); Modarresi, H. [Department of Mechanical Engineering, Sharif University of Technology, P.O. Box 11365-9567, Tehran (Iran, Islamic Republic of)

2009-01-15

262

Runaway electron energy measurement using hard x-ray spectroscopy in "Damavand" tokamak.  

PubMed

Set of experiments has been developed to study existing runaway electrons in "Damavand" tokamak plasma upon characteristics of hard x-ray emissions produced by collision of the runaway electrons with the plasma particles and limiters. As a first step, spatial distribution of hard x-ray emissions on the equatorial plane of the torus was considered. Obtained spectra of hard x-ray emissions for different alignments of shielded detector indicate isotropic emissivity in the equatorial plane. This is in agreement with wide angle cone of bremsstrahlung radiations, deduced from the mean value of energy of the runaway electrons. The mean energy was calculated from the slope of the energy spectrum of hard x-ray photons. In the second stage in order to investigate time evolution of energy of the runaway electrons, similar technique were applied to obtain hard x-ray energy in every 3 ms intervals, from the beginning to the end of plasma. The mean energy of the runaway electrons increases during the ramp up phase and reaches its maximum between 3 and 9 ms after plasma formation. Also considering the time dependence of the counted photons in each energy range shows that energetic photons are emitted during the ramp up phase of the plasma current in Damavand tokamak. PMID:19191433

Rasouli, C; Iraji, D; Farahbod, A H; Akhtari, K; Rasouli, H; Modarresi, H; Lamehi, M

2009-01-01

263

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

264

Compton scattering artifacts in electron excited X-ray spectra measured with a silicon drift detector.  

PubMed

Artifacts are the nemesis of trace element analysis in electron-excited energy dispersive X-ray spectrometry. Peaks that result from nonideal behavior in the detector or sample can fool even an experienced microanalyst into believing that they have trace amounts of an element that is not present. Many artifacts, such as the Si escape peak, absorption edges, and coincidence peaks, can be traced to the detector. Others, such as secondary fluorescence peaks and scatter peaks, can be traced to the sample. We have identified a new sample-dependent artifact that we attribute to Compton scattering of energetic X-rays generated in a small feature and subsequently scattered from a low atomic number matrix. It seems likely that this artifact has not previously been reported because it only occurs under specific conditions and represents a relatively small signal. However, with the advent of silicon drift detectors and their utility for trace element analysis, we anticipate that more people will observe it and possibly misidentify it. Though small, the artifact is not inconsequential. Under some conditions, it is possible to mistakenly identify the Compton scatter artifact as approximately 1% of an element that is not present. PMID:22067917

Ritchie, Nicholas W M; Newbury, Dale E; Lindstrom, Abigail P

2011-11-09

265

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

266

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

267

Development of suitable plastic standards for X-ray fluorescence analysis  

NASA Astrophysics Data System (ADS)

For the adoption of the EU directive “Restriction on use of certain Hazardous Substances” and “Waste Electrical and Electronic Equipment” using X-ray fluorescence analysis suitable standard materials are required. Plastic standards based on acrylonitrile butadiene styrene terpolymer, containing the regulated elements Br, Cd, Cr, Hg and Pb were developed and produced as granulates and solid bodies. The calibration materials were not generated as a dilution from one master batch but rather the element concentrations were distributed over nine independent calibration samples. This was necessary to enable inter-elemental corrections and empirical constant mass absorption coefficients. The produced standard materials are characterized by a homogenous element distribution, which is more than sufficient for X-ray fluorescence analysis. Concentrations for all elements except for Br could be determined by Inductively Coupled Plasma Atomic Emission Spectroscopy after microwave assisted digestion. The concentration of Br was determined by use of Neutron Activation Analysis at Hahn-Meitner-Institute in Berlin, Germany. The correlation of the X-ray fluorescence analysis measurements with the values determined using Inductively Coupled Plasma Atomic Emission Spectroscopy and Neutron Activation Analysis showed a very good linearity.

Mans, Christian; Hanning, Stephanie; Simons, Christoph; Wegner, Anne; Jan?en, Anton; Kreyenschmidt, Martin

2007-02-01

268

New X-ray microprobe system for trace heavy element analysis using ultraprecise X-ray mirror optics of long working distance  

Microsoft Academic Search

A new X-ray microprobe system for trace heavy element analysis using ultraprecise X-ray mirror optics of 300mm long working distance has been developed at beamline 37XU of SPring-8. A focusing test has been performed in the X-ray energy range 20–37.7keV. A focused beam size of 1.3?m (V)×1.5?m (H) has been achieved at an X-ray energy of 30keV, and a total

Yasuko Terada; Hirokatsu Yumoto; Akihisa Takeuchi; Yoshio Suzuki; Kazuto Yamauchi; Tomoya Uruga

2010-01-01

269

Application of Nanometer-Multilayer Optics for X-Ray Analysis  

Microsoft Academic Search

With the growing number of applications in X-ray analysis, more and more dedicated X-ray optics are required, optimized for the spectral range they are intended to be used for. Three different types of curvature of laterally graded multilayer mirrors are used for X-ray analysis experiments: parabolic, elliptic and planar, which result in parallel, focusing and divergent beam conditions, respectively. Ni\\/C-multilayer-optics

Reiner Dietsch; Thomas Holz; Stefan Braun; Andreas Leson

2003-01-01

270

An x-ray microprobe beam line for trace element analysis  

SciTech Connect

The application of synchrotron radiation to an x-ray microprobe for trace element analysis is a complementary and natural extension of existing microprobe techniques using electrons, protons, and heavier ions as excitation sources for x-ray fluorescence. The ability to focus charged particles leads to electron microprobes with spatial resolutions in the sub-micrometer range and down to 100 ppM detection limits and proton microprobes with micrometer resolution and ppM detection limits. The characteristics of synchrotron radiation that prove useful for microprobe analysis include a broad and continuous energy spectrum, a relatively small amount of radiation damage compared to that deposited by charged particles, a highly polarized source which reduces background scattered radiation in an appropriate counting geometry, and a small vertical divergence angle of approx.0.2 mrad which allows for focussing of the light beam into a small spot with high flux. The features of a dedicated x-ray microprobe beam line developed at the National Synchrotron Light Source (NSLS) are described. 4 refs., 3 figs.

Gordon, B.M.; Hanson, A.L.; Jones, K.W.; Kwiatek, W.M.; Long, G.J.; Pounds, J.G.; Schidlovsky, G.; Spanne, P.; Rivers, M.L.; Sutton, S.R.

1987-01-01

271

X-Ray Fluorescence Analysis of Uranium Concentrates.  

National Technical Information Service (NTIS)

Uranium concentrates were analyzed by x-ray fluorescence for the following impurities: arsenic, calcium, iron, molybdenum, phosphorus, silicon, sulfur, thorium, and vanadium. All of the impurities except arsenic can be determined simultaneously. (ERA cita...

J. P. Diaz-Guerra A. Bayon M. Roca

1985-01-01

272

Inferring the electron temperature and density of shocked liquid deuterium using inelastic X-ray scattering  

NASA Astrophysics Data System (ADS)

An experiment designed to launch laser-ablation-driven shock waves (10 to 70 Mbar) in a planar liquid-deuterium target on the OMEGA Laser System and to diagnose the shocked conditions using inelastic x-ray scattering is described. The electron temperature (Te) is inferred from the Doppler-broadened Compton-downshifted peak of the noncollective (?s = 1k?D > 1) x-ray scattering for Te > TFermi. The electron density (ne) is inferred from the downshifted plasmon peak of the collective (?scatter > 1) x-ray scattering. A cylindrical layer of liquid deuterium is formed in a cryogenic cell with 8-?m-thick polyimide windows. The polyimide ablator is irradiated with peak intensities in the range of 1013 to 1015 W/cm2 and shock waves are launched. Predictions from a 1-D hydrodynamics code show the shocked deuterium has a thickness of ~0.1 mm with spatially uniform conditions. For the drive intensities under consideration, electron density up to ~5 × 1023 cm-3 and electron temperature in the range of 10 to 25 eV are predicted. A laser-irradiated saran foil produces Cl Ly?emission. The spectrally resolved x-ray scattering is recorded at 90° for the noncollective scattering and at 40° for the collective scattering with a highly oriented pyrolytic graphite (HOPG) crystal spectrometer and an x-ray framing camera.

Regan, S. P.; Radha, P. B.; Boehly, T. R.; Doeppner, T.; Falk, K.; Glenzer, S. H.; Goncharov, V. N.; Gregori, G.; Landen, O. L.; McCrory, R. L.; Meyerhofer, D. D.; Neumayer, P.; Sangster, T. C.; Smalyuk, V. A.

2010-08-01

273

Electronic Structure of AC-Clusters and High-Resolution X-ray Spectra of Actinides in Solids  

Microsoft Academic Search

Ab initio calculations using SCF approach for and analysis of results of investigation of the electronic structure of the clusters RAn+:[L]k with rare earths or actinides were carried out for the clusters in solids and liquids. Theoretical results for the electronic structure, radial integrals and energy of X- ray lines are presented for AC ions with unoccupied 5f-shell in the

Kulagin; Nicolay Alex

2007-01-01

274

Simulations of X-ray photoelectron diffraction for polytype analysis  

Microsoft Academic Search

Single scattering cluster (SSC) simulations are used to explore the possibilities and the limitations of X-ray photoelectron diffraction (XPD) with standard laboratory X-ray sources in the field of polytype determination of silicon carbide (SiC) films. We show that the bulk emission dominates the diffraction patterns at energies of more than 1 keV. Effects due to surface reconstructions can be ignored

Aimo Winkelmann; Bernd Schröter; Wolfgang Richter

2002-01-01

275

Experimental methods of X-ray stress analysis  

Microsoft Academic Search

A technique is described for measuring residual stresses in steels and composite materials by X-ray diffraction. Specimen\\u000a preparation, X-ray diffractometer alignment, diffraction-peak location, and the determination of the elastic modulus, Poisson's\\u000a ratio and stress factor are covered. Application examples include measurement of heat-treating and shot-peening stresses in\\u000a steels and grinding and temperature stresses in WC-Co composites.

D. N. French; B. A. MacDonald

1969-01-01

276

Capillary optics for micro x-ray fluorescence analysis  

NASA Astrophysics Data System (ADS)

Practically achieved parameters of capillary optics are presented. A micro x-ray fluorescence (XRF) arrangement was realized by using a microfocus x-ray tube and a capillary optic. Several examples for application of micro XRF are given. It was shown that polycapillary lenses free of the ``halo effect'' well suited for micro XRF of heavy elements can be manufactured. Limits of opportunities for micro XRF applications and further development for micro XRF by using capillary optics are analyzed.

Bjeoumikhov, A.; Langhoff, N.; Bjeoumikhova, S.; Wedell, R.

2005-06-01

277

Production of tunable monochromatic x rays by the Vanderbilt free-electron laser  

NASA Astrophysics Data System (ADS)

Sustained/long duration X-ray output has been demonstrated emanating from the monochromatic X-ray beamline of the Vanderbilt Free-Electron Laser. Tunable, pulsed monochromatic X-rays ranging in energy from 14 - 18 keV are produced by inverse Compton scattering created by the counter propagation of the FEL e-beam and its own infrared beam. These beams are focused and optimized at an interaction zone between the linac and the wiggler where they are brought into coalignment. The X-rays produced exit the beamline through a beryllium window and are directed onto mosaic crystals which divert the beam to an imaging laboratory on the floor above the vault. The initial application of these X-rays is directed toward human imaging, specifically for the diagnosis of breast diseases including cancer. The characteristics of the X-rays are such that they can be used in standard geometry monochromatic imaging, CT like images of the breast using a rotating mosaic crystal 'optic,' time-of-flight imaging and phase contrast images. Eventual extension to other portions of the body, cell biology and material sciences are already anticipated.

Carroll, Frank E.; Waters, James W.; Traeger, Robert H.; Mendenhall, Marcus H.; Clark, Weiwei; Brau, Charles A.

1999-07-01

278

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

279

X-ray diffraction analysis of multilayer porous InP(001) structure  

SciTech Connect

Multilayer structures composed of four porous bilayers have been studied by high-resolution X-ray diffraction using synchrotron radiation, and the photoluminescence of these structures has been investigated at 4 K. The porous structures were formed by anodic oxidation of InP(001) substrates in aqueous HCl solution. The structural parameters of the sublayers were varied by changing the electrochemical etching mode (potentiostatic/galvanostatic). The X-ray scattering intensity maps near the InP 004 reflection are obtained. A model for scattering from such systems is proposed based on the statistical dynamical diffraction theory. Theoretical scattering maps have been fitted to the experimental ones. It is shown that a mathematical analysis of the scattering intensity maps makes it possible to determine the structural parameters of sublayers. The reconstructed parameters (thickness, strain, and porosity of sublayers and the shape and arrangement of pores) are in satisfactory agreement with the scanning electron microscopy data.

Lomov, A. A., E-mail: a.lomov@ns.crys.ras.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Punegov, V. I. [Russian Academy of Sciences, Komi Research Center, Ural Division (Russian Federation); Vasil'ev, A. L. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Nohavica, D.; Gladkov, P. [Academy of Sciences of the Czech Republic, Institute of Photonics and Electronics (Czech Republic); Kartsev, A. A.; Novikov, D. V. [German Electron Synchrotron DESY (Germany)

2010-03-15

280

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

281

A comparison of Monte Carlo simulations of electron scattering and X-ray production in solids  

Microsoft Academic Search

Monte Carlo simulations of electron scattering in silver have been performed at 6 and 20 keV to investigate the relation between electron transport, backscattering and depth distribution of characteristic X-ray production of tracer elements. The simulation models used combine the use of elastic cross sections, either of Rutherford or of Mott type, with approaches to inelastic scattering given by either

Ding Ze-Jun; Wu Ziqin

1993-01-01

282

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

283

Effects of beam-tube roughness on x-ray free electron laser performance  

Microsoft Academic Search

In an x-ray free electron laser like the Linear Coherent Light Source being designed at SLAC, electron bunches about 70mum FWHM long are sent into a beam tube only 5 mm in internal diameter and more than 100 m in length. Because of the surface roughness of the beam tube, wakefields can be generated that catch up to the bunch

Gennady Stupakov; Ruth Ellen Thomson; Dieter Walz; Roger Carr

1999-01-01

284

X-ray spectroscopy of highly-ionized atoms in an electron beam ion trap (EBIT)  

SciTech Connect

An Electron Beam Ion Trap at Lawrence Livermore National Laboratory is being used to produce and trap very-highly-charged-ions (q /le/ 70+) for x-ray spectroscopy measurements. Recent measurements of dielectronic recombination, electron impact excitation and transition energies are presented. 15 refs., 12 figs., 1 tab.

Marrs, R.E.; Bennett, C.; Chen, M.H.; Cowan, T.; Dietrich, D.; Henderson, J.R.; Knapp, D.A.; Levine, M.A.; Schneider, M.B.; Scofield, J.H.

1988-01-01

285

Approach to Accurate X-ray Mask Measurements in a Scanning Electron Microscope,  

National Technical Information Service (NTIS)

The paper presents the concept and some preliminary experimental data on a new method for measuring critical dimensions on masks used for x-ray lithography. The method uses a scanning electron microscope (SEM) in a transmitted-scanning electron microscope...

M. T. Postek R. D. Larrabee W. J. Keery

1989-01-01

286

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

287

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

288

Rapid qualitative phase analysis in highly textured thin films by x-ray diffraction.  

PubMed

Phase analysis of highly out-of-plane textured specimens using x-ray diffraction is usually complicated due to the disappearance of most of the x-ray peaks in a common theta/2 theta diffraction geometry. In this paper, we propose a technique, where powderlike spectra of textured samples are obtained by multiaxial x-ray diffraction scans. This technique is a simple, yet powerful method which allows for significant improvement in thin film characterization and provides several types of information about the samples, such as the rapid qualitative identification of phases using common powder x-ray diffraction spectra databases, texture distribution, and quantitative residual stress analysis. PMID:18447532

Borgia, Cesare; Olliges, Sven; Spolenak, Ralph

2008-04-01

289

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

290

Multielement trace analysis of solid and liquid samples by X-ray fluorescence  

Microsoft Academic Search

Summary The use of energy-dispersive multielement X-ray analysis is described and the radionuclides109Cd and241Am and X-ray tubes combined with secondary targets are compared as X-ray sources. Solid powdered samples of “infinite” thickness are used without further treatment. Calibration standards are prepared from silica gel, and correction factors are derived from the peak heights of Compton scattering. Results for various geological

K. H. Lieser; E. Breitwieser; P. Burba; M. Röber; R. Spatz

1978-01-01

291

Development of an automated x-ray gauge for nondestructive quantitative analysis  

Microsoft Academic Search

This report describes an x-ray gauging system developed in the Materials Characterization Department at Sandia for nondestructive quantitative analysis. The automated device utilizes the transmission of low-energy x-rays through a material in order to measure the areal density of the material. If the material density is known, the x-ray gauge serves as a non-contacting thickness gauge, typically for micron-range dimensions.

Drotning

1988-01-01

292

Macroporous silicon membranes as electron and x-ray transmissive windows  

SciTech Connect

Macroporous silicon membranes are fabricated whose pores are terminated with 60 nm thin silicon dioxide shells. The transmission of electrons with energies of 5 kV-25 kV through these membranes was investigated reaching a maximum of 22% for 25 kV. Furthermore, the transmission of electromagnetic radiation ranging from the far-infrared to the x-ray region was determined. The results suggest the application of the membrane as window material for electron optics and energy dispersive x-ray detectors.

Schilling, J.; Scherer, A.; Goesele, U.; Kolbe, M. [California Institute of Technology, 391 S. Holliston Avenue, Pasadena, California, 91125 (United States); Max Planck Institute of Microstructure Physics, Halle (Germany); Physikalisch-Technische Bundesanstalt, Berlin (Germany)

2004-08-16

293

Boiling the Vacuum with an X-Ray Free Electron Laser  

Microsoft Academic Search

X-ray free electron lasers will be constructed in this decade, both at SLAC\\u000ain the form of the so-called Linac Coherent Light Source as well as at DESY,\\u000awhere the so-called TESLA XFEL laboratory uses techniques developed for the\\u000adesign of the TeV energy superconducting electron-positron linear accelerator\\u000aTESLA. Such X-ray lasers may allow also for high-field science applications by

A. Ringwald

2003-01-01

294

Simulations of a Johann/Johansson diffraction spectrometer for x-ray experiments at an electron beam ion source  

NASA Astrophysics Data System (ADS)

The ray tracing simulations of x-ray spectra for a compact six-crystal Johann/Johansson diffraction spectrometer covering a wide photon energy range (70 eV-15 keV), i.e. from the extended ultraviolet to the hard x-ray region, are discussed in the context of x-ray experiments at an electron beam ion source facility. In particular, the x-ray line profiles and energy resolution for different diffraction crystals and multilayers were studied, and the effects of extension of x-ray source size and misalignment were investigated. The simulations were also performed for x-ray emission from solid targets bombarded by electrons, which will be used for calibration of the x-ray spectrometer.

Jab?o?ski, ?.; Jagodzi?ski, P.; Bana?, D.; Pajek, M.

2013-09-01

295

Suprathermal-electron pumping of x-ray lasers  

SciTech Connect

Very high flux densities of suprathermal electrons with energies up to several hundred keV, can be produced by focusing high power laser beams to small spots on solid surfaces. If these suprathermal electrons can be confined in a sufficiently small volume, they can produce significant 3p ..-->.. 3s and 4 ..-->.. 3 population inversions in highly stripped medium Z ions.

Carman, R.L.; Chapline, G.F.

1981-12-15

296

Human soft tissue analysis using x-ray or gamma-ray techniques.  

PubMed

This topical review is intended to describe the x-ray techniques used for human soft tissue analysis. X-ray techniques have been applied to human soft tissue characterization and interesting results have been presented over the last few decades. The motivation behind such studies is to provide improved patient outcome by using the data obtained to better understand a disease process and improve diagnosis. An overview of theoretical background as well as a complete set of references is presented. For each study, a brief summary of the methodology and results is given. The x-ray techniques include x-ray diffraction, x-ray fluorescence, Compton scattering, Compton to coherent scattering ratio and attenuation measurements. The soft tissues that have been classified using x-rays or gamma rays include brain, breast, colon, fat, kidney, liver, lung, muscle, prostate, skin, thyroid and uterus. PMID:18451465

Theodorakou, C; Farquharson, M J

2008-05-01

297

TOPICAL REVIEW: Human soft tissue analysis using x-ray or gamma-ray techniques  

NASA Astrophysics Data System (ADS)

This topical review is intended to describe the x-ray techniques used for human soft tissue analysis. X-ray techniques have been applied to human soft tissue characterization and interesting results have been presented over the last few decades. The motivation behind such studies is to provide improved patient outcome by using the data obtained to better understand a disease process and improve diagnosis. An overview of theoretical background as well as a complete set of references is presented. For each study, a brief summary of the methodology and results is given. The x-ray techniques include x-ray diffraction, x-ray fluorescence, Compton scattering, Compton to coherent scattering ratio and attenuation measurements. The soft tissues that have been classified using x-rays or gamma rays include brain, breast, colon, fat, kidney, liver, lung, muscle, prostate, skin, thyroid and uterus.

Theodorakou, C.; Farquharson, M. J.

2008-06-01

298

A different approach to X-ray stress analysis  

NASA Astrophysics Data System (ADS)

A different approach to X-ray stress analysis has been developed. At the outset, it must be noted that the material to be analyzed is assumed homogeneous and isotropic. If a sphere with radius r within a specimen is subjected to a state of stress, the sphere is deformed into an ellipsoid. The semi-axes of the ellipsoid have the values of (r + ?x), (r + ?y), and (r + ?z), which are replaced by dx, dy, and dz, or for the cubic case, ax, ay, and az. In this technique, at a particular ? angle (see ), the two-theta position of a high angle (hkl) peak is determined at ? angles of 0, 15, 30, and 45°. These measurements are repeated for 3 to 6 ? angles in steps of 30°. The d?? or a?? values are then determined from the peak positions. The data is then fitted to the general quadratic equation for an ellipsoid by the method of least squares. From the coefficients of the quadratic equation, the angle between the laboratory and the specimen coordinates (direction of the principle stress) can be determined. Applying the general rotation of axes equations to the quadratic, the equation of the ellipse in the x y plane is determined. The ax, ay, and az values for the principal axes of the lattice parameter ellipsoid are then evaluated. It is then possible to determine the unstressed a0 value from Hooke's Law using ax, ay, and az. The magnitude of the principal strains/stresses is then determined.

Ogilvie, Robert E.

2007-07-01

299

X-ray amplification from a Raman free-electron laser.  

PubMed

We demonstrate that a mm-scale free-electron laser can operate in the x-ray range, in the interaction between a moderately relativistic electron bunch, and a transverse high intensity optical lattice. The corrugated light-induced ponderomotive potential acts simultaneously as a guide and as a low-frequency wiggler, triggering stimulated Raman scattering. The gain law in the small signal regime is derived in a fluid approach, and confirmed from particle-in-cell simulations. We describe the nature of bunching, and discuss the saturation properties. The resulting all-optical Raman x-ray laser opens perspectives for ultracompact coherent light sources up to the hard x-ray range. PMID:23368329

Andriyash, I A; d'Humières, E; Tikhonchuk, V T; Balcou, Ph

2012-12-10

300

Hard x-ray and hot electron environment in vacuum hohlraums at the National Ignition Facility  

SciTech Connect

Time resolved hard x-ray images (hv>9 keV) and time integrated hard x-ray spectra (hv=18-150 keV) from vacuum hohlraums irradiated with four 351 nm wavelength National Ignition Facility [J. A. Paisner, E. M. Campbell, and W. J. Hogan, Fusion Technol. 26, 755 (1994)] laser beams are presented as a function of hohlraum size, laser power, and duration. The hard x-ray images and spectra provide insight into the time evolution of the hohlraum plasma filling and the production of hot electrons. The fraction of laser energy detected as hot electrons (F{sub hot}) shows a correlation with laser intensity and with an empirical hohlraum plasma filling model. In addition, the significance of Au K-alpha emission and Au K-shell reabsorption observed in some of the bremsstrahlung dominated spectra is discussed.

McDonald, J.W.; Suter, L.J.; Landen, O.L.; Foster, J.M.; Celeste, J.R.; Holder, J.P.; Dewald, E.L.; Schneider, M.B.; Hinkel, D.E.; Kauffman, R.L.; Atherton, L.J.; Bonanno, R.E.; Dixit, S.N.; Eder, D.C.; Haynam, C.A.; Kalantar, D.H.; Koniges, A.E.; Lee, F.D.; MacGowan, B.J.; Manes, K.R. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States)] (and others)

2006-03-15

301

Performance of the x-ray free-electron laser oscillator with crystal cavity  

NASA Astrophysics Data System (ADS)

Simulations of the x-ray free-electron laser (FEL) oscillator are presented that include the frequency-dependent Bragg crystal reflectivity and the transverse diffraction and focusing using the two-dimensional FEL code GINGER. A review of the physics of Bragg crystal reflectors and the x-ray FEL oscillator is made, followed by a discussion of its numerical implementation in GINGER. The simulation results for a two-crystal cavity and realistic FEL parameters indicate ˜109 photons in a nearly Fourier-limited, ps pulse. Compressing the electron beam to 100 A and 100 fs results in comparable x-ray characteristics for relaxed beam emittance, energy spread, and/or undulator parameters, albeit in a larger radiation bandwidth. Finally, preliminary simulation results indicate that the four-crystal FEL cavity can be tuned in energy over a range of a few percent.

Lindberg, R. R.; Kim, K.-J.; Shvyd'Ko, Yu.; Fawley, W. M.

2011-01-01

302

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

303

Novel x-ray analysis methods using a MicroStrip gas chamber  

NASA Astrophysics Data System (ADS)

This paper presents two novel applications of X-ray diffraction studies and their preliminary results using an MSGC. One involves the rapid analysis of single crystal structures using information on both the position and timing of incident X-rays. With this application, crystal structures of organic molecules could be obtained in a measurement time of 1 approximately 10 minutes. The other involves time-resolved X-ray diffraction measurements on the order of milliseconds. The time variation of the SAXS (small angle X-ray scattering) pattern of the protein solution was measured up to a frame time of 10 milli-seconds.

Ochi, Atsuhiko; Tanimori, Toru; Nishi, Yuji; Nagayoshi, Tsutomu; Nishi, Yasuro; Ohashi, Yuji; Uekusa, Hidehiro; Toyokawa, Hidenori; Inoue, Katsuaki; Fujisawa, Tetsuro

1999-10-01

304

X-rays from radiative electron capture of highly-charged heavy ions in an electron cooler  

Microsoft Academic Search

The x-ray spectra induced by spontaneous capture of free cooling electrons into bare and hydrogenlike heavy ions have been observed. Au78+, Au79+ and U91+ ions were stored in the storage ring ESR at velocities between 60% and 65% of the velocity of light and the x rays were measured in coincidence with stored particles having captured one electron in the

D. Liesen; H. F. Beyer; K. D. Finlayson; F. Bosch; M. Jung; O. Klepper; R. Moshammer; K. Beckert; H. Eickhoff; B. Franzke; F. Nolden; P. Spädtke; M. Steck; G. Menzel; R. D. Deslattes

1994-01-01

305

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

306

Theory and analysis of soft x-ray laser experiments  

SciTech Connect

The atomic modeling of soft x-ray laser schemes presents a formidable challenge to the theorists - a challenge magnified by the recent successful experiments. A complex plasma environment with many ion species present must be simulated. Effects such as turbulence, time dependence, and radiation transport, which are very difficult to model accurately, may be important. We shall describe our efforts to model the recently demonstrated soft x-ray laser in collisionally pumped neon-like selenium, with emphasis on the ionization balance and excited state kinetics. The relative importance of various atomic processes, such as collisional excitation and dielectronic recombination, on the inversion kinetics will be demonstrated. We shall compare our models with experimental results and evaluate the success of this technique in predicting and analyzing the results of x-ray laser experiments. 22 refs., 5 figs., 3 tabs.

Whitten, B.L.; Hazi, A.U.

1985-10-01

307

Electron Energy Evolution in a 100-ns Plasma Opening Switch Investigated by X-ray Measurements  

NASA Astrophysics Data System (ADS)

Electrons with energies in the range of a several to hundreds of keV were observed using X-ray diagnostics during the operation of a Plasma Opening Switch (POS). The coaxial POS conducts a current of up to 170 kA, for a duration of up to 90 ns, through a prefilled plasma which has been spectroscopically diagnosed as having the initial parameters n_e=(2.2±0.5)×10^14 cm-3 and T_e=5.5± 1 eV. Measurements made with different metal foils and X-ray films provided the time integrated X-ray emission at various axial and azimuthal locations and gave an estimation of the extent of the electron energy range. The densitograms of the films showed a gradual enhancement in the X-ray production when moving from the generator side to the load side of the switch. The use of a fast scintillator (NE102) covered with similar metal foils and coupled to a photomultiplier tube by means of an optical fiber enabled time-resolved measurements of electron energy at different axial positions. While high energy (hundreds of keV) electrons were observed during the POS opening (as might be expected), electrons with energies ranging from several keV to tens of keV were detected during conduction.

Bogatu, I. N.; Grabowski, C.; Weingarten, A.; Maron, Y.

1998-11-01

308

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

309

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

NASA Astrophysics Data System (ADS)

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.; Gray, A. X.; Kaiser, A. M.; Mun, B. S.; Sell, B. C.; Kortright, J. B.; Fadley, C. S.

2013-02-01

310

Electronic Structure in Thin Film Organic Semiconductors Studied using Soft X-ray Emission and Resonant Inelastic X-ray Scattering  

SciTech Connect

The electronic structure of thin films of the organic semiconductors copper and vanadyl (VO) phthalocyanine (Pc) has been measured using resonant soft X-ray emission spectroscopy and resonant inelastic X-ray scattering. For Cu-Pc we report the observation of two discrete states near E{sub F}. This differs from published photoemission results, but is in excellent agreement with density functional calculations. For VO-Pc, the vanadyl species is shown to be highly localized. Both dipole forbidden V 3d to V 3d*, and O 2p to V 3d* charge transfer transitions are observed, and explained in a local molecular orbital model.

Zhang,Y.; Downes, J.; Wang, S.; Learmonth, T.; Plucinski, L.; Matsuura, A.; McGuinness, C.; Glans, P.; Bernardis, S.; et al.

2006-01-01

311

Split and Delay System for Soft X-ray Pump/Soft X-ray Probe Experiments at the LCLS Free Electron Laser  

NASA Astrophysics Data System (ADS)

We will report on the development of a mirror based x-ray split and delay system for soft x-rays at the Linac Coherent Light Source free electron laser. The instrument will be based on an edge-polished mirror design, using grazing incidence mirrors to cover an energy range up 2000 eV. Two mirrors located immediately after the AMO Kirkpatrick-Baez mirrors will split the FEL wavefront; one of these mirrors will be translated and rotated to produce a variable delay up to 100 femtoseconds.

Murphy, B. F.; Bozek, J.; Castagna, J. C.; Berrah, N.

2012-11-01

312

X-ray fluorescence spectrometry for high throughput analysis of atmospheric aerosol samples: The benefits of synchrotron X-rays  

NASA Astrophysics Data System (ADS)

The determination of trace element mass concentrations in ambient air with a time resolution higher than one day represents an urgent need in atmospheric research. It involves the application of a specific technique both for the aerosol sampling and the subsequent analysis of the collected particles. Beside the intrinsic sensitivity of the analytical method, the sampling interval and thus the quantity of collected material that is available for subsequent analysis is a major factor driving the overall trace element detection power. This is demonstrated for synchrotron radiation X-ray fluorescence spectrometry (SR-XRF) of aerosol samples collected with a rotating drum impactor (RDI) in hourly intervals and three particle size ranges. The total aerosol mass on the 1-h samples is in the range of 10 µg. An experimental detection of the nanogram amounts of trace elements with the help of synchrotron X-rays was only achievable by the design of a fit-for-purpose sample holder system, which considered the boundary conditions both from particle sampling and analysis. A 6-µm polypropylene substrate film has evolved as substrate of choice, due to its practical applicability during sampling and its suitable spectroscopic behavior. In contrast to monochromatic excitation conditions, the application of a 'white' beam led to a better spectral signal-to-background ratio. Despite the low sample mass, a counting time of less than 30 s per 1-h aerosol sample led to sufficient counting statistics. Therefore the RDI-SR-XRF method represents a high-throughput analysis procedure without the need for any sample preparation. The analysis of a multielemental mass standard film by SR-XRF, laboratory-based wavelength-dispersive XRF spectrometry and laboratory-based micro XRF spectrometry showed that the laboratory-based methods were no alternatives to the SR-XRF method with respect to sensitivity and efficiency of analysis.

Bukowiecki, Nicolas; Lienemann, Peter; Zwicky, Christoph N.; Furger, Markus; Richard, Agnes; Falkenberg, Gerald; Rickers, Karen; Grolimund, Daniel; Borca, Camelia; Hill, Matthias; Gehrig, Robert; Baltensperger, Urs

2008-09-01

313

Anisotropic x ray magnetic linear dichroism - Its importance for the analysis of soft x ray spectra of magnetic oxides  

SciTech Connect

Using spectroscopic information for x ray magnetometry and magnetic microscopy requires detailed theoretical understanding of spectral shape and magnitude of dichroism signals. We have shown unambiguously that--contrary to common belief--spectral shape and magnitude of x ray magnetic linear dichroism (XMLD) are not only determined by the relative orientation of magnetic moments and x ray polarization, but also their orientations relative to the crystallographic axes must be taken into account for accurate interpretation of XMLD data.

van der Laan, G.; Arenholz, Elke

2008-07-02

314

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 submicron particles containing organic and inorganic material. Several algorithms were developed to exploit NEXAFS spectral features in the energy range from 278-320 eV for quantitative mapping of the spatial distribution of elemental carbon, organic carbon, potassium, and non-carbonaceous 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 application of the automated mapping algorithms for data analysis and the statistical classification of particles.

Moffet, Ryan C.; Henn, Tobias R.; Laskin, Alexander; Gilles, Marry K.

2010-09-30

315

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.

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, Sebastien; Messerschmidt, Marc; Jogl, Gerwald; Dahlberg, Albert E.; Gregory, Steven T.; Bogan, Michael J.

2013-01-01

316

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

PubMed

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

2013-08-19

317

Electron charge distribution of CaAl2-xZnx: Maximum entropy method combined with Rietveld analysis of high-resolution-synchrotron X-ray powder diffraction data  

NASA Astrophysics Data System (ADS)

Using short wavelength X-rays from synchrotron radiation (SPring-8), high-resolution powder diffraction patterns were collected. In order to study both the structural relationship and the mechanism of stability in the CaAl2-xZnx system, among the Laves phases (MgCu2 and MgNi2 type) and KHg2-type structures, the charge density distribution of CaAl2-xZnx as a function of x was obtained from the diffraction data by Rietveld analysis combined with the maximum entropy method (MEM). In the MEM charge density maps overlapping electron densities were clearly observed, especially in the Kagomé nets of the Laves phases. In order to clarify the charge redistribution in the system, the deformation charge densities from the densities formed by the constituent free atoms are discussed. In the ternary MgNi2-type phase, partial ordering of Al and Zn atoms is observed, a finding that is supported by ab-initio total energy calculations.

Söderberg, Karin; Kubota, Yoshiki; Muroyama, Norihiro; Grüner, Daniel; Yoshimura, Arisa; Terasaki, Osamu

2008-08-01

318

A free-electron laser fourth-generation x-ray source  

SciTech Connect

The field of synchrotrons radiation research has grown rapidly over the last 25 years due to both the push of the accelerator and magnet technology that produces the x-ray beams and the pull of the extraordinary scientific research those beams make possible. Three successive generations of synchrotrons radiation facilities have resulted in beam brilliances 11 to 12 orders of magnitude greater than the standard laboratory x-ray tube. However, greater advances can be easily imagined given the fact that x-ray beams from present-day facilities do not exhibit the coherence or time structure so familiar with the.optical laser. Theoretical work over the last ten years or so has pointed to the possibility of generating hard x-ray beams with laser-like characteristics. The concept is based on self-amplified spontaneous emission in free electron lasers. The use of a superconducting linac could produce a major, cost-effective facility that spans wavelengths from the ultraviolet to the hard x-ray regime, simultaneously servicing large numbers experimenters from a wide range of disciplines. As with each past generation of synchrotron facilities, immense new scientific opportunities from fourth-generation sources.

Moncton, D. E.

1999-10-21

319

Fast electron studies using a multichord x-ray spectrometer on MST  

NASA Astrophysics Data System (ADS)

The X-ray spectroscopy diagnostic on MST consists of six SXR detectors and six HXR detectors capable of measuring photons in the energy range 3-25 keV and 10-60 keV, respectively. The detectors can be installed on any of 17 ports viewing a poloidal cross-section, with impact parameters from ra=0.87 inboard to ra=0.84 outboard. An updated code processes the digitized signals, providing the time and energy of photons incident on each detector, and is capable of resolving individual photons arriving at the detector less than 50 ns apart. The spatial resolution of the system may allow improved diagnosis of the QSH tearing mode on MST, including the x-ray enhancement and spatial structure. The system may be able to probe electron heating during magnetic reconnection, the counterpart to noncollisional ion heating observed during magnetic reconnection on MST. X-ray flux from multiple view chords are compared with prediction from the kinetic code CQL3D. X-ray measurements can be used to constrain CQL3D in order to estimate Zeff and radial diffusion profiles. Additionally, radially-localized x-ray measurements from lower hybrid current drive experiments are shown.

Lee, J. D.

2012-10-01

320

Fundamentals of inelastically scattered X-ray synchrotron radiation as a probe for the electronic structure of condensed matter  

Microsoft Academic Search

Several interactions of X-ray photons with the electrons of condensed matter are included under the general term ``inelastic scattering''. Each of these interactions can be established as the basis for the study of some electronic properties. X-ray Compton scattering is the only spectroscopical method in which the momentum and not the energy is of importance, while the X-ray resonant Raman

Nikos G. Alexandropoulos

1991-01-01

321

Precise delineation characteristics for 1×X-ray mask using advanced electron beam mask writer EB-X3  

Microsoft Academic Search

A variable-shaped electron beam (e-beam) mask writer, EB-X3 was developed for 100 nm node 1×X-ray mask fabrication. It features a stable electron column of 100 kV and the address unit of 1 nm. This paper describes delineation characteristics of the EB-X3 on X-ray membrane mask. We have evaluated image placement (IP) accuracy and e-beam proximity effects on the X-ray membrane

S. Tsuboi; H. Watanabe; M. Ezaki; H. Aoyama; Y. Kikuchi; Y. Nakayama; S. Ohki; T. Watanabe; T. Morosawa; K. Saito; M. Oda; T. Matsuda

2000-01-01

322

Simulation of heat transfer in zone plate optics irradiated by X-ray free electron laser radiation  

Microsoft Academic Search

Zone plates are high quality optics that have the potential to provide diffraction-limited nano-focusing of hard X-ray free electron laser radiation. The present publication investigates theoretically the temperature behavior of metal zone plates on a diamond substrate irradiated by 0.1nm X-rays from the European X-ray Free Electron Laser. The heat transfer in the optic is simulated by solving the transient

D. Nilsson; A. Holmberg; H. Sinn; U. Vogt

2010-01-01

323

A review of x-ray free-electron laser theory.  

SciTech Connect

High-gain free-electron lasers (FELs) are being developed as extremely bright sources for a next-generation x-ray facility. In this paper, we review the basic theory of the start-up, the exponential growth, and the saturation of the high-gain process, emphasizing the self-amplified spontaneous emission. The radiation characteristics of an x-ray FEL, including its transverse coherence, temporal characteristics, and harmonic content, are discussed. FEL performance in the presence of machine errors and undulator wakefields is examined. Various enhancement schemes through seeding and beam manipulations are summarized.

Huang, Z.; Kim, K.-J.; Accelerator Systems Division (APS); Stanford Linear Accelerator Center

2007-03-01

324

A Review of X-ray Free-Electron Laser Theory  

SciTech Connect

High-gain free-electron lasers (FELs) are being developed as extremely bright sources for a next-generation x-ray facility. In this paper, we review the basic theory of the startup, the exponential growth, and the saturation of the high-gain process, emphasizing the self-amplified spontaneous emission (SASE). The radiation characteristics of an x-ray FEL, including its transverse coherence, temporal characteristics, and harmonic content, are discussed. FEL performance in the presence of machine errors and undulator wakefields is examined. Various enhancement schemes through seeding and beam manipulations are summarized.

Huang, Zhirong; /SLAC; Kim, Kwang-Je; /ANL, APS

2006-12-18

325

Prospects for using X-ray free-electron lasers to investigate shock-compressed matter  

SciTech Connect

Within the next few years hard X-ray Free Electron Lasers will come on line. Such systems will have spectral brightnesses ten orders of magnitude greater than any extant synchrotron, with pulse lengths as short as a few femtoseconds. It is anticipated that large-scale optical lasers capable of shock-compressing matter to multi-megabar pressures will be sited alongside the X-ray source. We discuss how such systems can further our knowledge of shocked and isochorically heated matter, in particular investigating the potential to perform polycrystalline diffraction and the creation of warm dense matter.

Nagler, Bob; Higginbotham, Andrew; Kimminau, Giles; Murphy, William; Whitcher, Thomas; Wark, Justin [Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford, OX1 3PU (United Kingdom); Hawreliak, James; Kalantar, Dan; Lee, Richard; Lorenzana, Hector; Remington, Bruce [Lawrence Livermore National Laboratory, CA (United States); Larsson, Jorgen [University of Lund (Sweden); Park, Nigel [Atomic Weapons Establishment ltd. (United Kingdom); Sokolowski-Tinten, Klaus [University of Duisburg-Essen (Germany)

2007-12-12

326

Electronic Structure of Warm Dense Copper Studied by Ultrafast X-Ray Absorption Spectroscopy  

SciTech Connect

We use time-resolved x-ray absorption spectroscopy to investigate the unoccupied electronic density of states of warm dense copper that is produced isochorically through the absorption of an ultrafast optical pulse. The temperature of the superheated electron-hole plasma, which ranges from 4000 to 10 000 K, was determined by comparing the measured x-ray absorption spectrum with a simulation. The electronic structure of warm dense copper is adequately described with the high temperature electronic density of state calculated by the density functional theory. The dynamics of the electron temperature is consistent with a two-temperature model, while a temperature-dependent electron-phonon coupling parameter is necessary.

Cho, B. I.; Engelhorn, K.; Feng, J.; Heimann, P. A. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Correa, A. A.; Ogitsu, T.; Ping, Y.; Nelson, A. J.; Lee, R. W. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Weber, C. P. [Department of Physics, Santa Clara University, Santa Clara, California 95053 (United States); Lee, H. J. [Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Ni, P. A. [Accelerator and Fusion Research, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Prendergast, D. [Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Falcone, R. W. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Physics, University of California, Berkeley, California 94720 (United States)

2011-04-22

327

Basic properties of gas electron multipliers for cosmic X-Ray polarimeters  

Microsoft Academic Search

A gas electron multiplier (GEM) is a key device for the photoelectric X-ray polarimeters, which will be launched in the near future. Our GEMs have spatial resolution enough for tracking of photoelectrons and low risk of discharge. GEMs need to perform well in all sorts of tolerance tests for space missions before launch. As a result of gain stability test

T. Iwahashi; T. Tamagawa; A. Hayato; S. Nakamura; S. Konami; F. Asami; K. Makishima; N. Yasuda; H. Kitamura; H. Sakurai; F. Tokanai

2008-01-01

328

Electron-based EUV and ultrashort hard-x-ray sources  

NASA Astrophysics Data System (ADS)

A brief review of our progress in the realization of femtosecond laser-driven ultrashort hard-x-ray sources is given. New results on the development of electron-based compact EUV sources for "at-wavelength" metrology and next generation lithography are presented. AIP Conference Proceedings.

Egbert, A.; Mader, B.; Tkachenko, B.; Chichkov, B. N.

2002-11-01

329

Experimental ultra fast X-ray computed tomography with a linearly scanned electron beam source  

Microsoft Academic Search

We devised and tested a computed tomography approach that utilises a scanned electron beam X-ray source to produce fast tomographic image sequences of transient density distributions. Potential application areas for this technique are the visualisation and measurement of two-phase and particle flows in thermofluid dynamics research, chemical processes, or transport systems for fluids and bulk solids. In our setup we

U. Hampel; M. Speck; D. Koch; H.-J. Menz; H.-G. Mayer; J. Fietz; D. Hoppe; E. Schleicher; C. Zippe; H.-M. Prasser

2005-01-01

330

X-ray electron studies of iron and surface properties of lunar regolith from Mare Crisium  

Microsoft Academic Search

X-ray electron spectroscopy was used to study samples from the upper and lower parts of the Luna-24 regolith core from Mare Crisium. The upper layer exhibits a higher content of nonoxidized metallic iron, an increased content of silicon, and a decreased content of calcium on the surface (relative to the bulk) compared to the lower layer of the core. These

V. I. Nefedov; N. P. Sergushin; Ia. V. Salyn; Iu. M. Khirnyi; N. M. Zhavoronkov; V. S. Urusov

1980-01-01

331

Anomalous x-ray transmission in dislocation-free silicon after electron irradiation  

SciTech Connect

Changes in the anomalous x-ray transmission intensity upon electron irradiation of dislocation-free silicon crystals have been measured. The irradiation at 20 K produced large changes in the transmission of the (220) reflection (i.e., 5%). Some annealing experiments were done. Attempts to understand the large changes suggest that some of the point defects agglomerate forming dislocation loops during irradiation.

Fritsch, G.; Koehler, J.S.

1981-02-15

332

X-ray and electron diffraction study of polyimide LB films  

NASA Astrophysics Data System (ADS)

The fabrication of polyimide LB films was carried out via two stages. The structure of polyimide LB films was studied by X-ray small-angle scattering and electron diffraction methods. It was shown that the macromolecules were packed into an orthorhombic lattice with unit cell parameters: a = 0.631, b = 0.397, c = 3.2 nm.

Yanusova, L. G.; Stiopina, N. D.; Klechkovskaya, V. V.; Feigin, L. A.; Baklagina, Yu. G.; Kudryavtsev, V. V.; Sklizkova, V. P.

1994-04-01

333

An X-ray Converter of a Megavolt Electron Beam for Powerful Pulsed Generators  

Microsoft Academic Search

The problems of developing bremsstrahlung converters for powerful pulse electron diodes of high-current generators are analyzed. Designs for diode anodes, converter optimization guidelines, and methods for increasing the X-ray yield are discussed. The design of a new converter manufactured from a thin pressed tungsten wire placed between two plates of pyrolyzed graphite is reported. The use of this converter for

S. A. Dan’ko; G. I. Dolgachev; A. G. Ushakov

2005-01-01

334

The Application of High Energy X Rays and Electron Beams in Radiotherapy  

Microsoft Academic Search

It has been more than 25 years since very high energy x rays generated by a betatron were first used in the treatment of cancer. The development of these machines along with linear accelerators quickly led to the use of high energy electrons as an additional modality in cancer management. In the intervening years, the physical and biological aspects of

J. A. Purdy

1979-01-01

335

Theoretical studies of the electron scattering effect on developed pattern profiles in x-ray lithography  

Microsoft Academic Search

Monte Carlo calculations of the photo and Auger electron production by a monochromatic x ray of Al K? have been performed to study the effect of their diffusion in a 1.0-?m polymethyl methacrylate resist film on replicated patterns both with and without the Si substrate. Based on both the calculated spatial distribution of the absorbed energy density and the solubility

Kenji Murata

1985-01-01

336

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

337

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.

Schlichting, Ilme; Miao, Jianwei

2012-01-01

338

XPCS at the European x-ray free electron laser facility.  

SciTech Connect

The European X-ray free electron laser source (XFEL) will provide highly brilliant (B > 10{sup 33} ph/s/mm{sup 2}mrad{sup 2}/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, {omega}), which is of central importance for a variety of phenomena such as fast non-equilibrium dynamics initiated, e.g. by a short pump pulse. X-ray photon correlation spectroscopy (XPCS) measures the temporal changes in speckle patterns produced when coherent light is scattered by a disordered system and therefore allows to measure S(Q, t). This paper summarizes important aspects of the scientific case for an XPCS instrument at the planned XFEL. Novel XPCS set-ups are illustrated.

Grubel, G.; Stephenon, G. B.; Gutt, C.; Sinn, H.; Tschentscher, T.; Hasylab /DESY

2007-09-01

339

Measurements of Electron Anisotropy in Solar Flares Using Albedo with RHESSI X-Ray Data  

NASA Astrophysics Data System (ADS)

The angular distribution of electrons accelerated in solar flares is a key parameter in the understanding of the acceleration and propagation mechanisms that occur there. However, the anisotropy of energetic electrons is still a poorly known quantity, with observational studies producing evidence for an isotropic distribution and theoretical models mainly considering the strongly beamed case. We use the effect of photospheric albedo to infer the pitch-angle distribution of X-ray emitting electrons using Hard X-ray data from RHESSI. A bi-directional approximation is applied and a regularised inversion is performed for eight large flare events to deduce the electron spectra in both downward (towards the photosphere) and upward (away from the photosphere) directions. The electron spectra and the electron anisotropy ratios are calculated for a broad energy range, from about ten up to ˜ 300 keV, near the peak of the flares. The variation of electron anisotropy over short periods of time lasting 4, 8 and 16 seconds near the impulsive peak has been examined. The results show little evidence for strong anisotropy and the mean electron flux spectra are consistent with the isotropic electron distribution. The 3 ? level uncertainties, although energy and event dependent, are found to suggest that anisotropic distribution with anisotropy larger than ˜ three are not consistent with the hard X-ray data. At energies above 150 - 200 keV, the uncertainties are larger and thus the possible electron anisotropies could be larger.

Dickson, E. C. M.; Kontar, E. P.

2013-06-01

340

X-Ray Photoelectron Diffraction. Possibilities of Surface Structural Analysis  

Microsoft Academic Search

The current state of the X-ray photoelectron diffraction (XPD) method and its applications to solid state surface chemistry are overviewed in a systematic way. The fundamentals of the method are presented along with a number of approaches to its description: plane wave and spherical wave single scattering approximation, spherical wave multiple scattering approximation, and direct scattering and s-photoelectron scattering approximation.

E. V. Shalaeva; M. V. Kuznetsov

2003-01-01

341

Quantitative Mineralogical Analysis by X-ray diffraction.  

National Technical Information Service (NTIS)

Work was done in two phases on different combinations of soil-like crystalline materials that were mixed in the laboratory to develop a simple, rapid, and inexpensive method of doing quantitative mineralogical analyses, largely by X-ray diffraction (XRD)....

A. D. Buck

1972-01-01

342

X-RAY SPECTROMETRIC ANALYSIS FOR SOME REACTOR FUEL COMPONENTS  

Microsoft Academic Search

X-ray emission spectrometry has been found adaptable to quick, reliable ; aualysis for several of the fissionable and fission elements in fuel alloys and ; dilute aqueous solution. This method for milligram quantities of uranium in ; aqueous solution is in regular use. In sensitivity, reliability, aad time ; requirements, it is comparable to the spectrophotometric methods for uranium, ;

D. S. Flikkema; R. V. Schablaske; R. P. Larson

1958-01-01

343

TOPICAL REVIEW: Human soft tissue analysis using x-ray or gamma-ray techniques  

Microsoft Academic Search

This topical review is intended to describe the x-ray techniques used for human soft tissue analysis. X-ray techniques have been applied to human soft tissue characterization and interesting results have been presented over the last few decades. The motivation behind such studies is to provide improved patient outcome by using the data obtained to better understand a disease process and

C. Theodorakou; M. J. Farquharson

2008-01-01

344

Description of CORSET: a computer program for quantitative x-ray fluorescence analysis  

Microsoft Academic Search

Quantitative x-ray fluorescence analysis requires a method of correcting for absorption and secondary fluorescence effects due to the sample matrix. The computer program CORSET carries out these corrections without requiring a knowledge of the spectral distribution of the x-ray source, and only requires one standard per element or one standard containing all the elements. Sandia's version of CORSET has been

Stohl

1980-01-01

345

Ray-Trace Analysis of Glancing-Incidence X-Ray Optical Systems.  

National Technical Information Service (NTIS)

The results of a ray-trace analysis of several glancing-incidence X-ray optical systems are presented. The object of the study was threefold. First, the vignetting characteristics of the S-056 X-ray telescope were calculated using experimental data to det...

J. W. Foreman J. M. Cardone

1976-01-01

346

X-ray phase analysis of martensitic transformations in austenitic stainless steels electrochemically charged with hydrogen  

Microsoft Academic Search

Hydrogen concentration gradients, formed during electrochemical charging, inducing martensitic phase transformation in austenitic stainless steels, have been extensively studied with respect to the relative stability of the austenitic phase. Phase quantitative X-ray surface analysis of distributions of martensitic phases in a thin layer, comparable to the penetration depth of X-rays, based on diffraction data taken for various diffraction reflections (2?,

P. Rozenak; R. Bergman

2006-01-01

347

Theoretical Analysis of X-ray Compound Refractive Lens Optical Properties  

Microsoft Academic Search

We present a theoretical analysis of optical properties of parabolic compound refractive lenses (CRL). The parabolic CRL with a large number of elements is considered as a parabolic medium along the x-ray path. The problem of x-ray coherent wave propagation inside such a medium is solved exactly. The analytical formula is obtained for the parabolic CRL imaging propagator as a

V. Kohn; I. Snigireva; A. Snigirev

2004-01-01

348

Soft X-ray analysis of a loop flare on the Sun  

Microsoft Academic Search

We present the results of an analysis of soft X-ray images for a solar flare which occurred on 1992 July 11. This flare, as seen in Yohkoh Soft X-ray Telescope (SXT) images was of comparatively simple geometry, consisting of two bright footpoints early in the flare with a bright loop seen later in the flare. We examine how closely this

J. I. Khan; H. S. Hudson; Z. Mouradian

2004-01-01

349

Degradation of poly(methylmethacrylate) by deep ultraviolet, x-ray, electron beam, and proton beam irradiations  

Microsoft Academic Search

The chemical changes in poly(methylmethacrylate) (PMMA) caused by irradiation with deep ultraviolet (UV), x-ray, electron, and proton beams were studied by gel permeation chromatography, Fourier-transform infrared, and UV spectroscopy. The quantitative analysis of spectroscopic changes (Beer's law) demonstrated a 1:1 correspondence between the disappearance of ester groups and the generation of double bonds in the polymer chain by all types

J. O. Choi; J. A. Moore; J. C. Corelli; J. P. Silverman; H. Bakhru

1988-01-01

350

Characteristics of radiation safety for synchrotron radiation and X-ray free electron laser facilities.  

PubMed

Radiation safety problems are discussed for typical electron accelerators, synchrotron radiation (SR) facilities and X-ray free electron laser (XFEL) facilities. The radiation sources at the beamline of the facilities are SR, including XFEL, gas bremsstrahlung and high-energy gamma ray and photo-neutrons due to electron beam loss. The radiation safety problems for each source are compared by using 8 GeV class SR and XFEL facilities as an example. PMID:21493599

Asano, Yoshihiro

2011-04-14

351

New method of comparison for electron temperature measurements in plasmas using X-ray spectra of heavy elements  

SciTech Connect

Conditions and applicability limits of a new X-ray spectroscopy method for electron temperature measurements in plasmas of heavy elements are considered. The method is based on comparison of spectra under study with those of well diagnosed laser-produced plasmas. To apply the method for diagnosing tungsten plasmas a thorough analysis of laser-produced plasma spectra has been performed. The analysis included investigation of spectrum peculiarities and determination of electron temperatures. Quantitative data were obtained for determining electron temperatures in tungsten plasmas using relative intensities of spectral peaks in the spectral range {lambda} = 3 - 6 nm. (laser plasma)

Shevelko, A P [P N Lebedev Physical Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2011-08-31

352

Monte Carlo Simulation of the Conversion X-Rays from the Electron Beam of PFMA-3  

SciTech Connect

PFMA-3, a dense Plasma Focus device, is being optimized as an X-ray generator. X-rays are obtained from the conversion of the electron beam emitted in the backward direction and driven to impinge on a 50 {mu}m brass foil. Monte Carlo simulations of the X-ray emission have been conducted with MCNPX. The electron spectrum had been determined experimentally and is used in the present work as input to the simulations. Dose to the brass foil has been determined both from simulations and from measurements with a thermographic camera, and the two results are found in excellent agreement, thus validating further the electron spectrum assumed as well as the simulation set-up. X-ray emission has been predicted both from bremsstrahlung and from characteristic lines. The spectrum has been found to be comprised of two components of which the one at higher energy, 30 divide 70 keV, is most useful for IORT applications. The results are necessary to estimate penetration in and dose to Standard Human Tissue.

Ceccolini, E.; Mostacci, D.; Sumini, M. [Montecuccolino Nuclear Engineering Laboratory, University of Bologna, via dei Colli 16, I-40136 Bologna (Italy); Rocchi, F. [Montecuccolino Nuclear Engineering Laboratory, University of Bologna, via dei Colli 16, I-40136 Bologna (Italy); UTFISSM-PRONOC, ENEA, via Martiri di Monte Sole 4, I-40129 Bologna (Italy); Tartari, A. [Department of Physics, University of Ferrara, Via Saragat 1, I-44122 Ferrara (Italy)

2011-12-13

353

A Study of Accelerated Electrons in Solar Flares Using Microwave and X-Ray Observations  

NASA Astrophysics Data System (ADS)

We consider manifestations of accelerated electrons in microwave and hard X-ray emissions from solar flares. To meet our objectives, we discuss two events -- those of 1999 March 16 and February 16. The first event is a short-duration burst, while the second is a long-duration event. An analysis of the first event leads to the conclusion that: 1) a seemingly single-loop configuration can actually be a double-loop one, and 2) it is possible that the pitch-angle distribution of the radio-emitting electrons can be anisotropic with practically no non-zero pitch angles. The second event shows seemingly intersecting flaring loops, and the formation of a post-eruptive arcade that can proceed as a series of double-loop interactions. From these and other published results, we conclude that: 1) double-loop configurations can be responsible for flares showing diverse morphologies and time profiles; 2) the pitch-angle distribution of accelerated electrons can be strongly anisotropic, with an excess of small angles, contributing to a rather narrow energy range of the microwave-emitting electrons.

Grechnev, Victor V.; Kundu, Mukul R.; Nindos, Alexander

2006-02-01

354

Proposed Imaging of the Ultrafast Electronic Motion in Samples using X-Ray Phase Contrast  

NASA Astrophysics Data System (ADS)

Tracing the motion of electrons has enormous relevance to understanding ubiquitous phenomena in ultrafast science, such as the dynamical evolution of the electron density during complex chemical and biological processes. Scattering of ultrashort x-ray pulses from an electronic wave packet would appear to be the most obvious approach to image the electronic motion in real time and real space with the notion that such scattering patterns, in the far-field regime, encode the instantaneous electron density of the wave packet. However, recent results by Dixit et al. [Proc. Natl. Acad. Sci. U.S.A. 109, 11 636 (2012)] have put this notion into question and have shown that the scattering in the far-field regime probes spatiotemporal density-density correlations. Here, we propose a possible way to image the instantaneous electron density of the wave packet via ultrafast x-ray phase contrast imaging. Moreover, we show that inelastic scattering processes, which plague ultrafast scattering in the far-field regime, do not contribute in ultrafast x-ray phase contrast imaging as a consequence of an interference effect. We illustrate our general findings by means of a wave packet that lies in the time and energy range of the dynamics of valence electrons in complex molecular and biological systems. This present work offers a potential to image not only instantaneous snapshots of nonstationary electron dynamics, but also the Laplacian of these snapshots which provide information about the complex bonding and topology of the charge distributions in the systems.

Dixit, Gopal; Slowik, Jan Malte; Santra, Robin

2013-03-01

355

Hard X-ray Time-Resolved/Space-Resolved X-ray Absorption Fine Structure Analysis for Heterogeneous Metal Catalysts  

NASA Astrophysics Data System (ADS)

Our recent examples of time-resolved and space-resolved X-ray absorption fine structure (XAFS) for heterogeneous solid catalysts are highlighted. In-situ time-resolved XAFS analysis of heterogeneous catalysts has provided new pieces of information on the structures of real active species on heterogeneous catalyst surfaces and their dynamic structural changes under reaction conditions. The structural transformation and phase separation of Pt--Sn alloy particles on support surfaces and the structural kinetics and reaction mechanism of Pt/C and Pt3Co alloy/C cathode catalysts in polymer electrolyte fuel cells (PEFCs) were investigated by in-situ time-resolved XAFS. The recent development and example of space-resolved XAFS, which shows us microscopic structural information of practical catalyst particles, are also introduced.

Tada, Mizuki

2013-02-01

356

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

357

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...

358

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

359

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, Rui

2011-03-21

360

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

361

Fabrication, measurement, and analysis of multilayer x- ray diffraction gratings  

NASA Astrophysics Data System (ADS)

I examine the theory and fabrication of lamellar multilayer x-ray diffraction gratings. I use current theory based on the Kirchoff Integral for amplitude gratings and a new equation for phase gratings to analyze current technology multilayer grating performance (where the period/? exceeds 10). I examine the possible fabrication methods and define two general categories (additive: multilayer added to patterned substrate, subtractive: grating etched into multilayer). I conclude the additive approach is superior, leading to x-ray analogues to binary optics and holographic optical elements. I define an additive process in detail and demonstrate the serviceability of the key processes: thermal growth of silicon dioxide on silicon, lithography, a combined plasma-etch and wet-etch. Multilayer fabrication difficulties on patterned substrates are identified, including: mushroom cap growth, and filleting in the grooves. Measurements done at NSLS on 2 amplitude gratings and 1 phase grating are reported. The data is shown to be compatible with the Kirchoff theory.

Hansen, Douglas P.

1997-12-01

362

Gigavolt-Energy Electrons and Femtosecond-Duration Hard X-Rays Driven by Extreme Light  

NASA Astrophysics Data System (ADS)

The interactions of high-peak power laser light focused to extremely high intensity, or ``extreme light,'' is at the core of high-energy laser-driven electron accelerators, and novel laser-synchrotron x-ray light sources. The hallmark of extreme light is its ability to cause the instantaneous electron quiver motion to become relativistic. We discuss recent progress in understanding the physics of extreme light, and the advanced electron and x-ray technologies that it drives. Through the mechanism of relativistic self-guiding, focused light from our 100-TW Diocles laser was propagated in plasma at relativistic intensity for distance of 1 cm [corresponding to over 15 vacuum diffraction (Rayleigh) ranges]. As a result of this extended propagation length, electrons were accelerated by a laser-wakefield to near GeV energy in a well-collimated beam. The electron beam was measured to be tunable over a wide energy range, 100 -- 800 MeV, with 5-- 25% energy spread, and 1-- 4-mrad divergence angle. The experimental results were found to be in reasonable agreement with the results of numerical simulation, which predict even higher electron energy (multi-GeV) with our recently upgraded peak laser power (>0.5 PW). These characteristics, along with their lack of any measurable amount of dark-current, make these electron beams good candidates for driving synchrotron x-ray sources. The development of one such x-ray source will also be discussed, one driven by inverse Compton scattering of laser light by laser-accelerated electrons. Its small radiation source size (˜ 10 microns) and low angular beam divergence (< 10 mrad) make it quite promising for applications in radiology. By virtue of its ultra-short pulse duration (< 10 fs) and wide energy tunability (10 keV -- 10 MeV), it can also be used to probe matter with atomic-scale spatial and temporal resolution---simultaneously.

Umstadter, Donald

2012-06-01

363

An electron probe X-ray microanalytical study of bone mineral in osteogenesis imperfecta  

Microsoft Academic Search

A semiquantitative electron probe X-ray microan-alytical (XRMA) technique, in conjunction with transmission electron microscopy, was used to compare the calcium to phosphorus (Ca\\/P) molar ratios in calcium phosphate standards of known composition, in normal bone and in bone from patients with osteogenesis imperfecta (OI). Using a modified routine processing and resin embedding schedule, the measured Ca\\/P molar ratio of calcium

J. P. Cassella; N. Garrington; T. C. B. Stamp; S. H. Ali

1995-01-01

364

Computer-aided distal locking guidance of intramedullary nail by x-ray image analysis  

NASA Astrophysics Data System (ADS)

Distal locking of intramedullary nail inside a patient"s broken bone is a difficult step in an orthopaedic surgery. It is hard not only because surgeons must locate the direction and align two distal holes in a 3D space by using 2D x-ray images, but also because the intramedullary nail can twist in unknown 3D direction and position during an operation. This process normally takes a long time, heavily uses x-ray radiation and hence exposes surgeons and patients to high doses of x-ray radiation. Longer surgical duration also increases the risk of high blood loss and prolonged anesthesia towards the patient. This research proposes a methodology to help reduce the usage of x-ray radiation, and to also simplify the distal locking process, through the utilization of simple devices along with x-ray image analysis.

Covavisaruch, Nongluk; Simmami, Kamthon; Vatanawood, Wiwat; Ratanachai, Winyou

2004-05-01

365

X-Ray Fluorescence (XRF) spectrometry for materials analysis and discovering "the atomic number"  

NSDL National Science Digital Library

In this experiment students use XRF spectroscopy to analyze a sampleâs elemental composition. From the characteristic X-ray energies, Moseleyâs Law, a proof of the existence of the atomic number, is verified. The atomic number increases in regular steps with an increase in the characteristic X-ray energy. We will use this relationship to find the Rydbergâs energy constant and screening coefficient for K X-rays. This lab is designed for the student to learn to: 1. differentiate between characteristic X-rays and Bremsstrahlung radiations, 2. use characteristic X-rays to identify elements, 3. acquire a spectrum, calibrate it and use it for qualitative (element identification) as well as quantitative (elemental concentration) analysis, and finally, 4. verify Moseleyâs law and the validity of an atomic number.

Khalid, Asma; Khan, Aleena T.; Anwar, Muhammad S.

2012-06-06

366

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

367

Electronic Structure of AC-Clusters and High-Resolution X-ray Spectra of Actinides in Solids  

SciTech Connect

Ab initio calculations using SCF approach for and analysis of results of investigation of the electronic structure of the clusters RAn+:[L]k with rare earths or actinides were carried out for the clusters in solids and liquids. Theoretical results for the electronic structure, radial integrals and energy of X- ray lines are presented for AC ions with unoccupied 5f-shell in the clusters in oxides, chlorides and fluorides environment. Possibility of collapse of nf-shell for the separate clusters and identification of electronic state of ions with unstable nuclei, are discussed, too. (author)

Kulagin, Nicolay Alex [Physics Department, Kharkov National University for Radio Electronics, Khakov (Ukraine)

2007-07-01

368

Status of the liquid-metal-jet-anode electron-impact x-ray source  

NASA Astrophysics Data System (ADS)

We have demonstrated a new electron-impact hard-x-ray source based on a liquid-metal-jet anode in a proof-of-principle experiment. Initial calculations show that this new anode concept potentially allows a >100x increase in source brightness compared to today's compact hard-x-ray sources. In this paper we report on the scale up of the system to medium electron-beam power resulting in a brightness comparable to current state-of-the-art sources. The upgraded system combines a ~20-?m diameter liquid-tin jet operating at ~60 m/s with a 50 kV, 600 W electron beam focused to ~150 ?m FWHM. We describe the properties of the current system, experimental results, as well as a brief discussion of key issues for future high-power scaling.

Otendal, Mikael; Tuohimaa, Tomi; Hemberg, Oscar E.; Hertz, Hans M.

2004-11-01

369

High-intensity electron beam for liquid-metal-jet anode hard x-ray generation  

NASA Astrophysics Data System (ADS)

We report on our progress towards the experimental realization of a liquid-metal-jet-anode x-ray source with high brightness. We have previously shown that this electron-impact source has potential for very high x-ray brightness by combining small-spot high-flux operation of the electron beam with high-speed operation of the regenerative liquid-metal-jet anode. In the present paper we review the system and describe theoretical calculations for improving the 50 kV, 600 W electron-beam focussing to ~30 ?m spot size. With such a system the power density on the liquid-metal-jet would be ~400 kW/mm2, i.e., more than an order of magnitude higher than the power density on a state-of-the-art rotating anode.

Tuohimaa, Tomi; Otendal, Mikael; Hertz, Hans M.

2005-08-01

370

Unit cell determination in CuZr martensite by electron microscopy and X-ray diffraction  

SciTech Connect

As several other binary alloy compounds, stoichiometric CuZr has a B2 phase with a CsCl type bcc based structure. In the present system this phase appears as a line compound between 715 C and 935 C. Rapid cooling to below 140 C transforms this phase into at least two monoclinic structures which have been shown to have martensitic characteristics, not unusual for B2 phase alloys, including shape memory behavior. Unit cell dimensions for both monoclinic phases, one about twice the size of the other, were previously suggested on the basis of powder X-ray diffractometry and limited electron microscopy results. The aim of the current investigation was to confirm or correct these unit cells by extensive selected area electron diffraction (SAED), high resolution electron microscopy (HREM) and improved fitting procedures of the existing X-ray diffraction data. The crystallographic relation between parent and product phases will also be discussed.

Schryvers, D.; Seo, J.W. [RUCA, Antwerpen (Belgium); Firstov, G.S.; Koval, Yu.N. [National Academy of Sciences, Kiev (Ukraine). Inst. for Metal Physics; Humbeeck, J. Van [K.U. Leuven, Heverlee (Belgium)

1997-05-15

371

Boiling the Vacuum with AN X-Ray Free Electron Laser  

NASA Astrophysics Data System (ADS)

X-ray free electron lasers will be constructed in this decade, both at SLAC in the form of the so-called Linac Coherent Light Source as well as at DESY, where the so-called TESLA XFEL laboratory uses techniques developed for the design of the TeV energy superconducting electron-positron linear accelerator TESLA. Such X-ray lasers may allow also for high-field science applications by exploiting the possibility to focus their beams to a spot with a small radius, hopefully in the range of the laser wavelength. Along this route one obtains very large electric fields, much larger than those obtainable with any optical laser of the same power. We consider here the possibility of obtaining an electric field so high that electron-positron pairs are spontaneously produced in vacuum (Schwinger pair production) and review the prospects to verify this non-perturbative production mechanism for the first time in the laboratory.

Ringwald, A.

2004-10-01

372

Manipulating quantum entanglement of quasiparticles in many-electron systems by attosecond x-ray pulses  

SciTech Connect

Photoexcited electrons and holes in molecules or in semiconductors constitute a bipartite entangled system. We show that this entanglement can be coherently controlled by broadband x-ray pulses which create valence excitation wave packets through a stimulated Raman process. A novel measure of electron correlations in excited states is then provided by the time dependence of the concurrence. In a simulation study we demonstrate the control of entanglement of electrons and holes in CO that can be achieved by tuning a soft x-ray pulse to different core transitions: the carbon K edge (296 eV), the oxygen K edge (540 eV), and the 2{sigma}{yields}1{pi}{sup *} transition (191 eV).

Mukamel, Shaul; Wang, Haitao [Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025 (United States)

2010-06-15

373

Using the X-ray free-electron laser to drive a photo-pumped helium-like neon X-ray laser at 23 nm  

NASA Astrophysics Data System (ADS)

Nearly four decades ago resonantly photo-pumped laser schemes based on hydrogen-like and helium-like ions were proposed for producing X-ray lasers. These schemes have yet to be demonstrated because of the difficulty of finding a strong pump line with an adequate resonance to pump the laser transition. With the construction of the X-ray free-electron laser (X-FEL) at the SLAC Linac Coherent Light Source (LCLS) researchers now have a very bright tunable X-ray laser source that can be used to replace the pump line in previously proposed laser schemes and allow one to study the physics and feasibility of photo-pumped laser schemes. In this paper we model the sodium-pumped neon X-ray laser scheme that was proposed and studied many years ago by replacing the Na He-? pump line at 1127 eV with the X-FEL. Using the X-FEL to photo-ionize Ne down to He-like Ne and then photo-pump the He-? line we predict gains greater than 400 cm -1 on the 4f - 3d transition at 23.1 nm in He-like Ne. The 4d - 3p line at 23.16 nm and the 4p - 3s line at 22.27 nm are also predicted to lase strongly.

Nilsen, Joseph; Scott, Howard A.

2011-03-01

374

X-ray and photoelectron spectroscopy of the structure, reactivity, and electronic structure of semiconductor nanocrystals  

SciTech Connect

Semiconductor nanocrystals are a system which has been the focus of interest due to their size dependent properties and their possible use in technological applications. Many chemical and physical properties vary systematically with the size of the nanocrystal and thus their study enables the investigation of scaling laws. Due to the increasing surface to volume ratio as size is decreased, the surfaces of nanocrystals are expected to have a large influence on their electronic, thermodynamic, and chemical behavior. In spite of their importance, nanocrystal surfaces are still relatively uncharacterized in terms of their structure, electronic properties, bonding, and reactivity. Investigation of nanocrystal surfaces is currently limited by what techniques to use, and which methods are suitable for nanocrystals is still being determined. This work presents experiments using x-ray and electronic spectroscopies to explore the structure, reactivity, and electronic properties of semiconductor (CdSe, InAs) nanocrystals and how they vary with size. Specifically, x-ray absorption near edge spectroscopy (XANES) in conjunction with multiple scattering simulations affords information about the structural disorder present at the surface of the nanocrystal. X-ray photoelectron spectroscopy (XPS) and ultra-violet photoelectron spectroscopy (UPS) probe the electronic structure in terms of hole screening, and also give information about band lineups when the nanocrystal is placed in electric contact with a substrate. XPS of the core levels of the nanocrystal as a function of photo-oxidation time yields kinetic data on the oxidation reaction occurring at the surface of the nanocrystal.

Hamad, K.S.

2000-05-01

375

Non-destructive analysis of uranium and\\/or plutonium using X-ray (K or L band) fluorescence excited by sealed sources or X-ray tubes  

Microsoft Academic Search

Uranium, plutonium and, more generally, high atomic number elements can be analyzed by excitation of their K or L X-rays by sealed sources or by X-ray tubes. The Radionuclides Application Branch of the CEA Ionizing Radiation Metrology and Applications Department has designed several industrial prototypes for non-destructive analysis of actinides at different nuclear fuel cycle stages in various matrices: e.g.,

J. L. Szabo; A. C. Simon; R. Junca

1994-01-01

376

Local x-ray structure analysis of optically manipulated biological micro-objects  

SciTech Connect

X-ray diffraction using micro- and nanofocused beams is well suited for nanostructure analysis at different sites of a biological micro-object. To conduct in vitro studies without mechanical contact, we developed object manipulation by optical tweezers in a microfluidic cell. Here we report x-ray microdiffraction analysis of a micro-object optically trapped in three dimensions. We revealed the nanostructure of a single starch granule at different points and investigated local radiation damage induced by repeated x-ray exposures at the same position, demonstrating high stability and full control of the granule orientation by multiple optical traps.

Cojoc, Dan; Ferrari, Enrico; Santucci, Silvia C. [Laboratorio TASC, Istituto Officina dei Materiali IOM-CNR, Trieste 34149 (Italy); Amenitsch, Heinz; Sartori, Barbara; Rappolt, Michael; Marmiroli, Benedetta [Institute for Biophysics and Nanosystems Research, Austrian Academy of Sciences, 8042 - Graz (Austria); Burghammer, Manfred; Riekel, Christian [ID13 Microfocus Beamline, European Synchrotron Radiation Facility, 38043 - Grenoble (France)

2010-12-13

377

X-ray diffraction analysis of NLO single crystals: traditional and nontraditional applications  

NASA Astrophysics Data System (ADS)

The present paper deals with the traditional and some new applications of the single crystal x-ray diffraction analysis of NLO materials. Traditionally, x-ray diffraction is used to prove molecular structure of a compound of interest, to establish crystal space group, packing array and features of the molecular geometry. This approach has been used in analysis of a large series of new organic NLO chromophores including substituted dicyanovinylaromatics, and some other NLO materials. Most of the compounds studied were found to demonstrate high molecular second-order optical susceptibilities. It was shown for the series of substituted dicyanovinylbenzenes what factors are responsible for the centric or acentric crystal structure of a given compound. Several new compounds of the series studied were found to exhibit a rather strong second harmonic generation signal in the solid state, in particular, 0-fluoro-dicyanovinylbenzene, p-dimethylamino- dicyanovinylbenzene, and 4-(4-methoxyphenyl)-1,1-dicyano- 1,3-butadiene, 4-MeO-C6H4-CHequalsCH-CHequalsC(CN)2. Molecular and crystal structures of these compounds have been studied and analyzed. Another new application of the x- ray diffraction method in the study of NLO compounds is analysis of the electron density distributions in crystal and direct estimation of some of its characteristics responsible for NLO properties directly from the diffraction data. These opportunities of the method were demonstrated in the charge density study of crystals of DIVA and nMA. Second order optical susceptibilities were estimated from the diffraction data using a multiple model and were found to be close to the experimental values.

Antipin, Mikhail Y.; Clark, Ronald D.; Nesterov, Vladimir N.; Lyssenko, Konstantin A.; Timofeeva, Tatiana V.

1998-10-01

378

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

379

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

380

Ultrafast structural dynamics with table top femtosecond hard X-ray and electron diffraction setups  

NASA Astrophysics Data System (ADS)

The following tutorial review is directed to graduate students willing to be part of the emerging field of ultrafast structural dynamics. It provides them with an introduction to the field and all the very basic assumptions and experimental tricks involved in femtosecond (fs) diffraction techniques. The concept of stroboscopic photography and its implication in ultrafast science are introduced. Special attention is paid to the generation of ultrashort electron and hard X-ray pulses in table top setups, and a direct comparison in terms of brightness and temporal resolution between current table top and facility-based methodologies is given for proper calibration. This review is focused on ultrafast X-ray and electron diffraction techniques. The progress in the development of fs-structural probes during the last twenty years has been tremendous. Current ultrafast structural probes provide us with the temporal and spatial resolutions required to observe atoms in motion. Different compression approaches have made it possible the generation of ultrashort and ultrabright electron pulses with an effective brightness close to that of fs-hard X-ray pulses produced by free electron lasers. We now have in hand a variety of ultrafast structural cameras ready to be applied for the study of an endless list of dynamical phenomena at the atomic level of inspection.

Hada, M.; Pichugin, K.; Sciaini, G.

2013-07-01

381

Accelerated electrons and hard X-ray emission from X-pinches  

SciTech Connect

The generation of accelerated electrons in the X-pinch minidiode is studied experimentally. It is well known that the explosion of an X-pinch consisting of two or more wires is accompanied by the formation of a minidiode, in which electrons are accelerated. The subsequent slowing down of electrons in the products of wire explosion causes the generation of hard X-ray (HXR) emission with photon energies higher than 10 keV. In this work, the spatial and temporal characteristics of X-pinch HXR emission are studied, the specific features of HXR generation are discussed, and the capability of applying this radiation to point-projection X-ray imaging of various plasma and biological objects is considered. The parameters of the electron beam produced in the X-pinch are measured using a Faraday cup and X-ray diagnostics. The experiments were performed with the XP generator (550 kA, 100 ns) at Cornell University (United States) and the BIN generator (270 kA, 150 ns) at the Lebedev Physical Institute (Russia).

Shelkovenko, T. A.; Pikuz, S. A.; Mingaleev, A. R.; Agafonov, A. V.; Romanova, V. M.; Ter-Oganes'yan, A. E.; Tkachenko, S. I. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Blesener, I. C.; Mitchell, M. D.; Chandler, K. M.; Kusse, B. R.; Hammer, D. A. [Cornell University (United States)

2008-09-15

382

X-ray absorption spectroscopic investigation of the electronic structure differences in solution and crystalline oxyhemoglobin.  

PubMed

Hemoglobin (Hb) is the heme-containing O2 transport protein essential for life in all vertebrates. The resting high-spin (S = 2) ferrous form, deoxy-Hb, combines with triplet O2, forming diamagnetic (S = 0) oxy-Hb. Understanding this electronic structure is the key first step in understanding transition metal-O2 interaction. However, despite intense spectroscopic and theoretical studies, the electronic structure description of oxy-Hb remains elusive, with at least three different descriptions proposed by Pauling, Weiss, and McClure-Goddard, based on theory, spectroscopy, and crystallography. Here, a combination of X-ray absorption spectroscopy and extended X-ray absorption fine structure, supported by density functional theory calculations, help resolve this debate. X-ray absorption spectroscopy data on solution and crystalline oxy-Hb indicate both geometric and electronic structure differences suggesting that two of the previous descriptions are correct for the Fe-O2 center in oxy-Hb. These results support the multiconfigurational nature of the ground state developed by theoretical results. Additionally, it is shown here that small differences in hydrogen bonding and solvation effects can tune the ground state, tipping it into one of the two probable configurations. These data underscore the importance of solution spectroscopy and show that the electronic structure in the crystalline form may not always reflect the true ground-state description in solution. PMID:24062465

Wilson, Samuel A; Green, Evan; Mathews, Irimpan I; Benfatto, Maurizio; Hodgson, Keith O; Hedman, Britt; Sarangi, Ritimukta

2013-09-23

383

Calibration Standards for X-Ray Spectrometers Used for Pollution Sample Analysis.  

National Technical Information Service (NTIS)

A technique is described for making aerosol standards for x-ray fluorescence analysis by depositing sized particles suspended in a carrier solution onto the surface of a polycarbonate filter. Size is controlled by a separate sedimentation step following g...

R. A. Semmler R. G. Draftz

1978-01-01

384

Industrial Method of X-Ray Fluorescence Analysis of High-Strength Steels.  

National Technical Information Service (NTIS)

A potential method of quantitative analysis of high-strength steels by x-ray fluorescence was investigated. A technique for measuring composition is described in the report. Tool steel, stainless steel, and high temperature alloys of widely varying compos...

D. W. Bowman R. J. Rodgers

1967-01-01

385

Design and Analysis of a Fast, Two-Mirror Soft-X-ray Microscope.  

National Technical Information Service (NTIS)

During the past several years, a number of investigators have addressed the design, analysis, fabrication, and testing of spherical Schwarzschild microscopes for soft-x-ray applications using multilayer coatings. Some of these systems have demonstrated di...

D. L. Shealy C. Wang W. Jiang L. Jin R. B. Hoover

1992-01-01

386

Automated Staging of Coal Workers' Pneumoconiosis Utilizing Digital Image Analysis of Chest X-rays.  

National Technical Information Service (NTIS)

This final report covers research designed to determine the feasibility of automated staging of coal worker's pneumoconiosis using digital image analysis of chest X-rays. A system which can potentially aid the radiologist in the classification of CWP from...

K. Preston E. K. Witt

1996-01-01

387

Liquid-metal-jet anode electron-impact x-ray source  

NASA Astrophysics Data System (ADS)

We demonstrate an anode concept, based on a liquid-metal jet, for improved brightness in compact electron-impact x-ray sources. The source is demonstrated in a proof-of-principle experiment where a 50 keV, ~100 W electron beam is focused on a 75 ?m liquid-solder jet. The generated x-ray flux and brightness is quantitatively measured in the 7-50 keV spectral region and found to agree with theory. Compared to rotating-anode sources, whose brightness is limited by intrinsic thermal properties, the liquid-jet anode could potentially be scaled to achieve a brightness >100× higher than current state-of-the-art sources. Applications such as mammography, angiography, and diffraction would benefit from such a compact high-brightness source.

Hemberg, O.; Otendal, M.; Hertz, H. M.

2003-08-01

388

Design considerations for the magnetic system of a prototype x-ray free electron laser  

SciTech Connect

A number of difficult technical challenges need to be solved in the fields of accelerator and free-electron laser (FEL) technologies in order to build an X-ray FEL. One of the tasks well suited to the Advanced Photon Source Low Energy Undulator Test Line (LEUTL) is to take the intermediate step of solving some of the problems of single-pass FEL operation in the ultraviolet range. The existing Advanced Photon Source (APS) linac, in addition to its role of supply positrons for the APS storage ring, will also be used to generate the particle beam for the LEUTL. Here, the design of the magnetic system for the high gain soft x-ray free electron laser is described.

Vinokurov, N.A.; Dejus, R.; Friedsam, H.; Gluskin, E.S.; Maines, J.; Milton, S.V.; Moog, E.R.; Trakhtenberg, E.M.; Vasserman, I.B.

1997-04-01

389

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

2013-03-05

390

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

391

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

392

Multichord Time-Resolved Electron Temperature Measurements by the X-Ray Absorber-Foil Method on TFTR.  

National Technical Information Service (NTIS)

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 tran...

J. Kiraly M. Bitter P. Efthimion S. von Goeler B. Grek

1985-01-01

393

Critical analysis of soft X-ray cross section data  

NASA Astrophysics Data System (ADS)

A project is in progress in the national Bureau of Standards (NBS) Photon and Charged Particle Data Center to collect and evaluate photon cross section data in the X-ray region 100 eV to 100 keV. This project complements earlier NBS evaluations and compilations which focused primarily on energies above 10 keV. The NBS collection of experimental total attenuation coefficients (10 eV to above 10 GeV) abstracted from the literature is now computerized to facilitate use and for future updates. These experimental results have been compared systematically with a theoretical photoabsorption calculation by Scofield, and also with a semi-empirical compilation by Henke et al. Sample graphical comparisons of measured data with the Scofield theoretical results are presented here for silicon and uranium. Silicon data from an International Union of Crystallography project are also presented. Discrepancies and uncertainties in the various experimental data sets are typically 5 to 50% or more in the soft X-ray region. However, systematic trends can be seen which suggest that the Scofield theoretical values, taken as a whole, are not improved by the Hartree-Slater to Hartree-Fock renormalization in this photon energy region.

Saloman, E. B.; Hubbell, J. H.

1987-03-01

394

Using Pictorial Structures to Identify Proteins in X-ray Crystallographic Electron Density Maps  

Microsoft Academic Search

One of the most time-consuming steps in determining a protein's structure via x-ray crystallography is interpretation of the electron density map. This can be viewed as a computer-vision problem, since a density map is simply a three-dimensional image of a protein. However, due to the intractably large space of conformations the protein can adopt, building a protein model to match

Frank DiMaio; Jude Shavlik; George N. Phillips

2003-01-01

395

Fine-pitch and thick-foil gas electron multipliers for cosmic x-ray polarimeters  

Microsoft Academic Search

We have produced various gas electron multiplier foils (GEMs) by using laser etching technique for cosmic X-ray polarimeters. The finest structure GEM we have fabricated has 30 mum-diameter holes on a 50 mum-pitch. The effective gain of the GEM reaches around 5000 at the voltage of 570 V between electrodes. The gain is slightly higher than that of the CERN

Toru Tamagawa; Asami Hayato; Yorito Yamaguchi; Hideki Hamagaki; Shigehira Hashimoto; Masahide Inuzuka; Hiromasa Miyasaka; Ikuya Sakurai; Fuyuki Tokanai; Kazuo Makishima

2006-01-01

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

Low X-Ray Energy Fluorescence Gas Electron Multiplier (GEM) for XAS Studies  

Microsoft Academic Search

X-ray absorption spectroscopy at sub-keV energies dictates the use of detectors that can attain a good signal-to-noise ratio. We report a recent study undertaken at Science and Technology Facilities Council, Daresbury Laboratory to evaluate the performance of a gas electron multiplier (GEM) for this purpose. The main impetus of this study was to investigate the relevant parameters such as the

J. A. Mir; D. Sole; J. D. Lipp; R. Stephenson; J. A. Purton; S. L. P. Savin; A. V. Chadwick; L. O'Dell

2007-01-01

398

Introduction to the new science with X-ray free electron lasers  

Microsoft Academic Search

The arrival of the first hard X-ray free electron laser facilities promises new advances in structural dynamics and nanoscale imaging that will have impact across the sciences. This introductory review is intended to cover the basic physics behind this potential and illustrate the current state-of-the-art by discussing a number of recent findings from the LCLS facility at the Stanford Linear

J. P. Marangos

2011-01-01

399

Development of a total reflection X-ray fluorescence spectrometer for ultra-trace element analysis  

Microsoft Academic Search

A simple and fairly inexpensive total reflection X-ray fluorescence (TXRF) spectrometer has been designed, constructed and\\u000a realized. The spectrometer is capable of ultra-trace multielement analysis as well as performs surface characterization of\\u000a thin films. The TXRF setup comprises of an X-ray generator, a slit-collimator arrangement, a monochromator\\/cutoff-stage, a\\u000a sample reflector stage and an X-ray detection system. The glancing angle of

M. K. Tiwari; B. Gowrishankar; V. K. Raghuvanshi; R. V. Nandedkar; K. J. S. Sawhney

2002-01-01

400

Quantitative analysis results of CE-1 X-ray fluorescence spectrometer ground base experiment  

NASA Astrophysics Data System (ADS)

As the nearest celestial body to the earth, the moon has become a hot spot again in astronomy field recently. The element analysis is a much important subject in many lunar projects. Remote X-ray spectrometry plays an important role in the geochemical exploration of the solar bodies. Because of the quasi-vacuum atmosphere on the moon, which has no absorption of X-ray, the X-ray fluorescence analysis is an effective way to determine the elemental abundance of lunar surface. The CE-1 X-ray fluorescence spectrometer (CE-1/XFS) aims to map the major elemental compositions on the lunar surface. This paper describes a method for quantitative analysis of elemental compositions. A series of ground base experiments are done to examine the capability of XFS. The obtained results, which show a reasonable agreement with the certified values at a 30% uncertainty level for major elements, are presented.

Cui, Xing-Zhu; Wang, Huan-Yu; Zhang, Cheng-Mo; Chen, Yong; Zhang, Jia-Yu; Peng, Wen-Xi; Cao, Xue-Lei; Liang, Xiao-Hua; Wang, Jin-Zhou; Gao, Min; Yang, Jia-Wei

2008-01-01

401

Constraints on photon pulse duration from longitudinal electron beam diagnostics at a soft x-ray free-electron laser  

NASA Astrophysics Data System (ADS)

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 on matter at atomic length and ultrafast time scales possible. However, in order to take advantage of these unique light sources and to meet the strict requirements of many experiments in photon science, FEL photon pulse durations need to be known and tunable. This can be achieved by controlling the FEL driving electron beams, and high-resolution longitudinal electron beam diagnostics can be utilized to provide constraints on the expected FEL photon pulse durations. In this paper, we present comparative measurements of soft x-ray pulse durations and electron bunch lengths at FLASH. The soft x-ray pulse durations were measured by FEL radiation pulse energy statistics and compared to electron bunch lengths determined by frequency-domain spectroscopy of coherent transition radiation in the terahertz range and time-domain longitudinal phase space measurements. The experimental results, theoretical considerations, and simulations show that high-resolution longitudinal electron beam diagnostics provide reasonable constraints on the expected FEL photon pulse durations. In addition, we demonstrated the generation of soft x-ray pulses with durations below 50 fs (FWHM) after the implementation of the new uniform electron bunch compression scheme used at FLASH.

Behrens, C.; Gerasimova, N.; Gerth, Ch.; Schmidt, B.; Schneidmiller, E. A.; Serkez, S.; Wesch, S.; Yurkov, M. V.

2012-03-01

402

Atomic holography with electrons and x-rays: Theoretical and experimental studies  

SciTech Connect

Gabor first proposed holography in 1948 as a means to experimentally record the amplitude and phase of scattered wavefronts, relative to a direct unscattered wave, and to use such a {open_quotes}hologram{close_quotes} to directly image atomic structure. But imaging at atomic resolution has not yet been possible in the way he proposed. Much more recently, Szoeke in 1986 noted that photoexcited atoms can emit photoelectron of fluorescent x-ray wavefronts that are scattered by neighboring atoms, thus yielding the direct and scattered wavefronts as detected in the far field that can then be interpreted as holographic in nature. By now, several algorithms for directly reconstructing three-dimensional atomic images from electron holograms have been proposed (e.g. by Barton) and successfully tested against experiment and theory. Very recently, Tegze and Faigel, and Grog et al. have recorded experimental x-ray fluorescence holograms, and these are found to yield atomic images that are more free of the kinds of aberrations caused by the non-ideal emission or scattering of electrons. The basic principles of these holographic atomic imaging methods are reviewed, including illustrative applications of the reconstruction algorithms to both theoretical and experimental electron and x-ray holograms. The author also discusses the prospects and limitations of these newly emerging atomic structural probes.

Len, P.M. [Univ. of California, Davis, CA (United States). Dept. of Physics]|[Lawrence Berkeley National Lab., CA (United States)

1997-06-01

403

Optical control of hard X-ray polarization by electron injection in a laser wakefield accelerator  

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

404

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

405

X-ray diagnostics of fast electrons propagation in high density plasmas obtained by cylindrical compression  

NASA Astrophysics Data System (ADS)

We report on X-ray diagnostics results from an experiment on fast electrons propagation in cylindrically compressed targets. It was performed on the VULCAN TAW laser facility at RAL (UK) using four long pulses (1ns, 70 J each at 2?) to compress a cylindrical polyimide target filled with CH foam at 3 different initial densities. The cylindrical geometry allows us to reach temperatures and densities higher than those obtained in planar geometry compression. 2D hydrodynamic simulations predicted a core density range from 4 to 8 g/cm3 and a core temperature from 30 eV up to 175 eV at maximum compression. An additional short laser pulse (10 ps, 160 J at ?) was focused on a Ni foil at one of the cylinder edges in order to generate a fast electrons current propagating along the compressed target. A X-ray radiography diagnostic was implemented in order to estimate the core plasma conditions of the compressed cylinder. Moreover two Bragg X-ray spectrometers collected the K? fluorescence from the target so as to determine the variations of fast electrons population during the compression.

Vauzour, B.; Koenig, M.; Batani, D.; Baton, S.; Beg, F. N.; Benedetti, C.; Brambrink, E.; Chawla, S.; Dorchies, F.; Fourment, C.; Galimberti, M.; Gizzi, L. A.; Heathcote, R.; Higginson, D. P.; Hulin, S.; Jafer, R.; Köster, P.; Labate, L. L.; Lancaster, K. L.; MacKinnon, A. J.; MacPhee, A. G.; Nazarov, W.; Nicolaï, P. H.; Pasley, J.; Perez, F.; Ribeyre, X.; Richetta, M.; Santos, J. J.; Schurtz, G.; Sgattoni, A.; Spindloe, C.; Volpe, L.

2010-08-01

406

Electron-ion interaction cross sections determined by x-ray spectroscopy on EBIT  

SciTech Connect

The Livermore electron beam ion trap (EBIT) is used to measure electron-ion interactions with high-resolution x-ray spectroscopy. Measurements are presented of the K{alpha} x-ray emission of heliumlike Fe{sup 24+} that demonstrate the effect of various processes on the spectrum of highly charged heliumlike ions. In particular, we have studied how dielectronic recombination into high-n Rydberg levels and resonance excitation processes contribute to the x-ray emission near threshold for direct electron-impact excitation. From these and other measurements we infer the cross sections for impact excitation of heliumlike titanium, chromium, manganese, and iron. Comparing the results with theoretical cross sections from distorted-wave calculations we find excellent agreement for all transitions but the heliumlike resonance transition from 1s2p {sup 1}P{sub 1} to ground, whose excitation cross section is measured to be 10%--20% smaller than calculated. 36 refs., 6 figs., 1 tab.

Beiersdorfer, P.; Cauble, R.; Chantrenne, S.; Chen, M.; Knapp, D.; Marrs, R.; Phillips, T.; Reed, K.; Schneider, M.; Scofield, J.; Wong, K.; Vogel, D.; Zasadzinski, R. (Lawrence Livermore National Lab., CA (USA)); Wargelin, B. (California Univ., Berkeley, CA (USA). Space Sciences Lab.); Bitter, M.; von Goeler, S. (Princeton Univ., NJ (USA). Plasma Physics Lab.)

1991-06-26

407

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.

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

408

Diffuse Hard X-Ray Emission in Starburst Galaxies as Synchrotron from Very High Energy Electrons  

NASA Astrophysics Data System (ADS)

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 ±) can contribute to this emission, because starbursts have strong magnetic fields. We consider three sources of e ± at these energies: (1) primary electrons directly accelerated by supernova remnants, (2) pionic secondary e ± created by inelastic collisions between cosmic ray (CR) protons and gas nuclei in the dense interstellar medium of starbursts, and (3) pair e ± produced between the interactions between 10 and 100 TeV ?-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 ±. We compare these models to extant radio and GeV and TeV ?-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 ~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 -2.2 injection spectrum and a diffusive escape time of 10 Myr (E/3 GeV)-1/2 (h/100 pc). Neutrino observations by IceCube and TeV ?-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 ± from sources like pulsars in starbursts, which could enhance the synchrotron X-ray emission further.

Lacki, Brian C.; Thompson, Todd A.

2013-01-01

409

Extended X-Ray Absorption Fine Structure Analysis of Crystalline Germanium at High Pressure  

NASA Astrophysics Data System (ADS)

Germanium (Ge) is an important semiconductor and analog material for Silicon. Crystalline Ge undergoes a series of pressure-induced transitions, including metallization and electronic changes [2], and a series of structural changes measured by XRD. The first phase transition of crystalline Ge from a diamond to ?-Sn structure, which is accompanied by metallization, has been well-documented at around 13 GPa, but the sequence of structural transitions at higher pressures is still debated [3, 4, 5]. We studied the structure changes of a crystalline Ge sample up to 90 GPa using Extended X-Ray Absorption Fine Structure (EXAFS). Structural phase transitions were observed at approximately 20, 77, and 90 GPa. At these pressures, several prominent peak shifts occur. In order to determine the local structure of crystalline Ge, the data were analyzed using Athena and Artemis software. The pressure behavior of the Ge-Ge bond lengths has been obtained, and this analysis of the various local structures of Ge will shed light on the material’s behavior at high pressure. [1.] Itié, J.-P., Baudelet, F., Dartyge, E., Fontaine, A., Tolentino, H., & San Miguel, A., X-ray absorption spectroscopy and high pressure. High Pressure Res. 8, 697-702 (1992). [2.] Struzhkin, V. V. et al., Valence band x-ray emission spectra of compressed germanium. Phys. Rev. Lett. 96, 137402 (2006). [3.] Vohra, Y. K., K. E. Brister, S. Desgreniers, A. L. Ruoff, K. J. Chang, and M. L. Cohen, Phys. Rev. Lett. 56, 1944 (1986). [4.] Nelmes, R. J., H. Liu, S. A. Belmonte, J. S. Loveday, M. I. McMahon, D. R. Allan, D. Hausermann, and M. Hanfland, Phys. Rev. B 53, R2907 (1996). [5.] Takemura, K., et al., High-Pressure Structures of Ge above 100 GPa, Phys. Stat. Sol. B 223, 385 (2001).

Mu, K.; Baldini, M.; Mao, W. L.

2010-12-01

410

Disentangling atomic-layer-specific x-ray absorption spectra by Auger electron diffraction spectroscopy  

NASA Astrophysics Data System (ADS)

In order to investigate the electronic and magnetic structures of each atomic layer at subsurface, we have proposed a new method, Auger electron diffraction spectroscopy, which is the combination of x-ray absorption spectroscopy (XAS) and Auger electron diffraction (AED) techniques. We have measured a series of Ni LMM AED patterns of the Ni film grown on Cu(001) surface for various thicknesses. Then we deduced a set of atomic-layer-specific AED patterns in a numerical way. Furthermore, we developed an algorithm to disentangle XANES spectra from different atomic layers using these atomic-layer-specific AED patterns. Surface and subsurface core level shift were determined for each atomic layer.

Matsui, Fumihiko; Matsushita, Tomohiro; Kato, Yukako; Hashimoto, Mie; Daimon, Hiroshi

2009-11-01

411

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

412

Resonant X-ray Scattering Experiments on the Ordering of Electronic Degrees of Freedom  

NASA Astrophysics Data System (ADS)

Resonant X-ray scattering (RXS) has been developed as a powerful technique for observing orderings of electronic degrees of freedom: charge, spin, orbital, and multipoles. After a brief introduction of the RXS technique, we review some RXS experiments on the orderings in d and f electron systems with a strong correlation between electrons. The basic concept of RXS and the recent developments of the technique are described in this review paper. We also present future prospects of the studies using RXS for users.

Matsumura, Takeshi; Nakao, Hironori; Murakami, Youichi

2013-02-01

413

Coincident emission of a characteristic and a continuum x ray in electron-atom collisions  

SciTech Connect

An observation of the simultaneous emission of a characteristic {ital K} x ray and a continuum photon has been made for 70-keV electrons bombarding target atoms of Fe, Cu, Y, and Ag. The absolute cross section for Y and Ag agree well with a model that considers a contribution from both double-bremsstrahlung and electron-electron bremsstrahlung processes. The data for Fe and Cu, on the other hand, are about an order of magnitude higher than the model, suggesting the possibility of a resonant polarization bremsstrahlung contribution to the double-bremsstrahlung process.

Kahler, D.L.; Liu, J.; Quarles, C.A. (Texas Christian University, Fort Worth, Texas 76129 (United States))

1992-06-01

414

Can X-ray spectrum imaging replace backscattered electrons for compositional contrast in the scanning electron microscope?  

PubMed

The high throughput of the silicon drift detector energy dispersive X-ray spectrometer (SDD-EDS) enables X-ray spectrum imaging (XSI) in the scanning electron microscope to be performed in frame times of 10-100?s, the typical time needed to record a high-quality backscattered electron (BSE) image. These short-duration XSIs can reveal all elements, except H, He, and Li, present as major constituents, defined as 0.1 mass fraction (10 wt%) or higher, as well as minor constituents in the range 0.01-0.1 mass fraction, depending on the particular composition and possible interferences. Although BSEs have a greater abundance by a factor of 100 compared with characteristic X-rays, the strong compositional contrast in element-specific X-ray maps enables XSI mapping to compete with BSE imaging to reveal compositional features. Differences in the fraction of the interaction volume sampled by the BSE and X-ray signals lead to more delocalization of the X-ray signal at abrupt compositional boundaries, resulting in poorer spatial resolution. Improved resolution in X-ray elemental maps occurs for the case of a small feature composed of intermediate to high atomic number elements embedded in a matrix of lower atomic number elements. XSI imaging strongly complements BSE imaging, and the SDD-EDS technology enables an efficient combined BSE-XSI measurement strategy that maximizes the compositional information. If 10?s or more are available for the measurement of an area of interest, the analyst should always record the combined BSE-XSI information to gain the advantages of both measures of compositional contrast. PMID:21638289

Newbury, Dale E; Ritchie, Nicholas W M

2011-06-02

415

State-of-the-art and problems of X-ray diffraction analysis of biomacromolecules  

SciTech Connect

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. [Russian Academy of Sciences, Engelhardt Institute of Molecular Biology (Russian Federation)], E-mail: andreeva@eimb.ru

2006-12-15

416

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

417

THERMAL FINITE ELEMENT ANALYSIS X9 AND X29 X-RAY RING CROTCH RADIATION ABSORBERS.  

SciTech Connect

This report details the efforts by engineers at the National Synchrotron Light Source (NSLS) of Brookhaven National Laboratory (BNL) to evaluate the reliability of water-cooled radiation absorbers used in the NSLS X-ray ring. The absorbers on this report are part of the X-9 and X-29 dipole vacuum chambers. The absorbers are located at the intersection (crotch) of the beamline exit ports with the electron beam chamber, and are generally referred to as ''crotches''. The purpose of this analysis was to demonstrate the thermal reliability of the crotches under operating conditions that will be present over the expected life of the ring. The efforts described include general engineering layouts, engineering calculations, finite element analysis (FEA), results and conclusions of the analysis, and future design recommendations.

MERCADO-CORUJO,H.

1999-08-11

418

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

419

Local structure and oxidation state of uranium in some ternary oxides: X-ray absorption analysis  

NASA Astrophysics Data System (ADS)

We investigated the local atomic and electronic structures of two related systematic sets of ternary uranium oxides, NaUO3 KUO3 RbUO3 and BaUO3 Ba2U2O7 BaUO4, by measuring the X-ray absorption near edge structure (XANES). The results are compared with calculations based on a self-consistent real space full multiple scattering analysis. We found a very good agreement between measured and calculated spectra, which indicates that the uranium ions are in a pure U5+ oxidation state in these compounds. The low energy shoulder observed in the U L3 edge XANES is an intrinsic feature of the uranium unoccupied 6d electronic states of the U5+ ions within the studied materials. Specific double shoulder features in the higher energy range of the U L3 edge XANES can be interpreted as indicative of the pure cubic perovskite structure. Display Omitted

Soldatov, A. V.; Lamoen, D.; Konstantinovi?, M. J.; van den Berghe, S.; Scheinost, A. C.; Verwerft, M.

2007-01-01

420

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

421

X-ray-induced electronic structure change in CuIr{sub 2}S{sub 4}  

SciTech Connect

The electronic structure of CuIr{sub 2}S{sub 4} is investigated using various bulk-sensitive x-ray spectroscopic methods near the Ir L{sub 3} edge: resonant inelastic x-ray scattering (RIXS), x-ray absorption spectroscopy in the partial fluorescence yield mode, and resonant x-ray emission spectroscopy. A strong RIXS signal (0.75 eV) resulting from a charge-density-wave gap opening is observed below the metal-insulator transition temperature of 230 K. The resultant modification of electronic structure is consistent with the density functional theory prediction. In the spin- and charge-dimer disordered phase induced by x-ray irradiation below 50 K, we find that a broad peak around 0.4 eV appears in the RIXS spectrum.

Gretarsson, H.; Kim, Young-June [Department of Physics, University of Toronto, 60 St. George Street, Toronto, Ontario M5S 1A7 (Canada); Kim, Jungho; Casa, D.; Gog, T. [CMC-XOR, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Choi, K. R. [l-PEM, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Cheong, S. W. [l-PEM, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); R-CEM and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854 (United States)

2011-09-15

422

X-ray and electron scattering intensities of molecules calculated using density functional theory  

NASA Astrophysics Data System (ADS)

The elastic and total intensities for x-ray and high-energy electron scattering from the ten-electron hydride series has been calculated from Kohn-Sham orbitals using the BLYP, B3LYP and LSDA functionals, and compared to the previous Hartree-Fock and singles and doubles configuration interaction (SDCI) results of Wang [J. Wang, A. N. Tripathi, and V. H. Smith, Jr., J. Chem. Phys. 101, 4842 (1994)] in the same basis. In those cases where density functional theory (DFT) provides a significantly better electron density than Hartree-Fock, the pair density and hence total scattering intensity for x-rays is also better reproduced, especially in the low s region. The asymptotic behavior of the scattering curves from the DFT methods is poorer than Hartree-Fock due to the inability of DFT to reliably predict the density at the nucleus, the electron-electron distribution at zero-electron separation, and the second moment of the electron-electron distribution.

Smith, Garry T.; Tripathi, Awadh N.; Smith, Vedene H.

1999-05-01

423

Energetic electrons and x-ray photons from multiterawatt Ti:sapphire lasers  

SciTech Connect

The energy distribution and yield of electrons and hard x-ray photons were investigated by irradiating tungsten and tantalum targets with {approx} 30 fs pulses in the intensity range 10{sup 18} - 10{sup 19} W cm{sup -2} by using the Laboratoire d'Optique Appliquee (LOA) as well as the Max Born Institut (MBI) multiterawatt Ti:sapphire lasers. For the measurement of the hard x-ray emission in the energy range from 15 keV to 700 keV at the LOA a 9-channel spectrometer of calibrated thermoluminescence detectors (TLD) was used. The scaling of the hard x-rays was studied by varying the incident laser energy within one order of magnitude and the pulsewidth by a factor of 5. The hot electron output was investigated in the range 300 keV - 1 MeV with the new MBI Ti:sapphire laser by using a time-of-flight spectrometer. The results indicate a sensitive interplay between the temporal laser shape and laser intensity. (interaction of laser radiation with matter. laser plasma)

Nickles, P V; Kalachnikov, M P; Warwick, P J; Janulewicz, K A; Sandner, W [Max-Born-Institut, Berlin (Germany); Jahnke, U; Hilscher, D [Hahn-Meitner-Institut, Berlin (Germany); Schnurer, M [Technische Universitat Wien, Vienna (Austria); Nolte, R [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Rousse, A [Laboratoire d'Optique Appliquee, ENSTA-Centre del'Yvette, Palaiseau (France)

1999-05-31

424

Applications of X-Ray Characterization for Advanced Materials in the Electronics Industry  

NASA Astrophysics Data System (ADS)

Nanometer thick films, quantum dots, and quantum wires are the basis of the modern electronic industry. X-ray diffraction techniques play an increasingly important role as basic characterization tools for determining detailed structural information of ultrathin film such as the evolution of strain relaxation, defect formation, film/substrate interfacial properties, and the effects of the reduced dimensionality and structural correlations to electrical properties. Materials of technological interest are SiGe and strained Si; artificial substrates such as silicon on insulator; high- and low- ? dielectric materials, which will substitute SiO2; materials for interconnects; new materials for memory storage; micro-electro-mechanical systems (MEMS); and photovaltaics. An overview of the major X-ray scattering applications of interest to this industry will be presented in this article.

Vigliante, A.; Kasper, N.; Brechbuehl, J.; Nolot, E.

2010-05-01

425

Simulation Studies of the X-Ray Free-Electron Laser Oscillator  

SciTech Connect

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 that the saturated x-ray pulses have 109 photons and are nearly Fourier-limited with peak powers in excess of 1 MW. Wealso include preliminary results for a four-mirror cavity that can be tuned in wavelength over a few percent, with future plans to incorporate the full transverse response of the Bragg crystals into GINGER to more accurately model this tunable source.

Lindberg, R. R.; Shyd'ko, Y.; Kim, K.-J; Fawley, W. M.

2009-08-14

426

A single-shot transmissive spectrometer for hard x-ray free electron lasers  

NASA Astrophysics Data System (ADS)

We report hard x-ray single-shot spectral measurements of the Linac Coherent Light Source. The spectrometer is based on a 10 ?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

2012-07-01

427

Novel algorithms in coherent diffraction imaging using x-ray free-electron lasers  

NASA Astrophysics Data System (ADS)

The emergence of X-ray Free-Electron Lasers has enabled coherent diffraction imaging of single nanoparticles by outrunning radiation damage with an intense ultrafast X-ray pulse. A 3D reconstruction from an ensemble of 2D diffraction patterns requires recovery of the orientations of individual diffraction patterns. This assumes that each diffraction pattern comes from a slice of a common diffraction volume. In the presence of particle heterogeneity, this assumption does not hold and the recovered structure is severely degraded. In this paper, I review couple of emerging algorithms useful for dealing with conformational changes in a heterogeneous sample. A simulated case study of a "particle in motion" is included to demonstrate the algorithms and also show that these novel algorithms work in the presence of missing Fourier regions caused by new detector geometries at XFEL facilities.

Yoon, Chunhong

2012-10-01

428

In-situ stoichiometry determination using x-ray fluorescence generated by reflection-high-energy-electron-diffraction  

SciTech Connect

A major challenge in the stoichiometric growth of complex oxide compounds is the control of the relative compositions of the constituent materials. A potential avenue for compositional analysis during growth is the use of x-ray fluorescence generated during reflection high energy electron diffraction measurements. Using this technique, relative compositions of Y and Mn in molecular beam epitaxy grown YMnO{sub 3} samples were studied. Comparing the results with Rutherford back scattering spectroscopy suggests that the technique has the potential for real-time analysis of elemental fluxes and stoichiometry control during sample growth.

Keenan, Cameron; Chandril, Sandeep; Lederman, David [Department of Physics and Multifunctional Materials Laboratory, West Virginia University, Morgantown, West Virginia 26506 (United States); Myers, T. H. [Department of Physics and Multifunctional Materials Laboratory, West Virginia University, Morgantown, West Virginia 26506 (United States); Materials Science, Engineering, and Commercialization Program, Texas State University-San Marcos, San Marcos, Texas 78666 (United States)

2011-06-01

429

Comparison of SR-excited X-ray fluorescence analysis with neutron activation analysis for hair and fiber  

Microsoft Academic Search

Human scalp hair and some kinds of vegetable and animal fibers were analyzed by means of the SR excited X-ray fluorescence\\u000a method (SRXFA) and the neutron activation method (NAA). Human hair samples collected from five males and five females were\\u000a washed by the IAEA method prior to analysis. In the SRXFA analysis, samples were excited by monochromated X-rays. Fluorescence\\u000a X-rays

Naoki Saitoh; Takao Suzuki; Tohru Kishi; Atsuo Iida; Yohichi Gohshi

1987-01-01

430

A flexible and accurate quantification algorithm for electron probe X-ray microanalysis based on thin-film element yields  

NASA Astrophysics Data System (ADS)

Quantitative analysis by means of electron probe X-ray microanalysis (EPXMA) of low Z materials such as silicate glasses can be hampered by the fact that ice or other contaminants build up on the Si(Li) detector beryllium window or (in the case of a windowless detector) on the Si(Li) crystal itself. These layers act as an additional absorber in front of the detector crystal, decreasing the detection efficiency at low energies (<5 keV). Since the layer thickness gradually changes with time, also the detector efficiency in the low energy region is not constant. Using the normal ZAF approach to quantification of EPXMA data is cumbersome in these conditions, because spectra from reference materials and from unknown samples must be acquired within a fairly short period of time in order to avoid the effect of the change in efficiency. To avoid this problem, an alternative approach to quantification of EPXMA data is proposed, following a philosophy often employed in quantitative analysis of X-ray fluorescence (XRF) and proton-induced X-ray emission (PIXE) data. This approach is based on the (experimental) determination of thin-film element yields, rather than starting from infinitely thick and single element calibration standards. These thin-film sensitivity coefficients can also be interpolated to allow quantification of elements for which no suitable standards are available. The change in detector efficiency can be monitored by collecting an X-ray spectrum of one multi-element glass standard. This information is used to adapt the previously determined thin-film sensitivity coefficients to the actual detector efficiency conditions valid on the day that the experiments were carried out. The main advantage of this method is that spectra collected from the standards and from the unknown samples should not be acquired within a short period of time. This new approach is evaluated for glass and metal matrices and is compared with a standard ZAF method.

Schalm, O.; Janssens, K.

2003-04-01

431

Electron probe X-ray microanalysis of residual bodies in aged cultured human glial cells  

SciTech Connect

Secondary lysosomes of the residual body type are frequent in nondividing cells from phase III cultures of human glial cells. These organelles have previously been shown to be analogous to lipofuscin granules of postmitotic cells in vivo. Most recent studies favor the assumption that residual bodies mainly result from incomplete degradation within the lysosomal vacuome of endogenous cellular components such as mitochondria and endoplasmic reticulum. Since iron occurs in several metalloenzymes produced by such organelles, it should then be possible to demonstrate accumulated iron within residual bodies. X-ray dispersive analysis of sectioned biological material is often hampered by diffusion and dissolution during preparation, as well as by too low a concentration of the elements. In this study we cultured glial cells on Formvar-coated gold grids and studied them unsectioned, after brief glutaraldehyde fixation and freeze-drying, in a transmission electron microscope at 100 kV in TEM and STEM mode. It was then possible to demonstrate iron in residual bodies of aged cells, presumably because the type of preparation utilized does not permit much dissolution.

Blomquist, E.; Fredriksson, B.A.; Brunk, U.

1980-01-01

432

Modeling and analysis of soft-test\\/repair for CCD-based digital X-ray systems  

Microsoft Academic Search

Modern X-ray imaging systems evolve toward digitization for reduced cost, faster time-to-diagnosis, and improved diagnostic confidence. For the digital X-ray systems, charge coupled device (CCD) technology is commonly used to detect and digitize optical X-ray image. This paper presents a novel soft-test\\/repair approach to overcome the defective pixel problem in CCD-based digital X-ray systems through theoretical modeling and analysis of

B. Jin; K. M. George; Minsu Choi; M. B. Yeary

2003-01-01

433

Development of an x-ray imaging proportional counter and an analysis of Tycho's supernova remnant  

SciTech Connect

A soft X-ray imaging proportional counter was developed for use in X-ray astronomy. The detector, a drift multiwire proportional counter, determines the position of the site of X-ray absorption in the detector in two orthogonal directions using the center-of-gravity centroid determination technique. Spatial resolutions of 0.2 millimeters full width at half maximum and 0.5 millimeters full width at half maximum have been obtained at X-ray energies of 0.94 and 0.28 kiloelectron volts, respectively. Energy resolutions of 65 percent full width at half maximum and 110 percent full width at half maximum have been obtained at these energies. The detector and processing electronics were integrated into a rocket-borne X-ray telescope payload capable of providing angular resolutions of 1.0 arcminutes full width at half maximum and 1.3 arcminutes full width at half maximum at X-ray energies of 0.94 and 0.28 kiloelectron volts, respectively. X-ray imaging observations of Tycho's supernova remnant were obtained with the Einstein Observatory imaging proportional counter. The remnant appears as an incomplete shell of radius 3.5 parsecs in the adiabatic phase of evolution. The X-ray and radio shells are spatially coincident, although uncorrelated in intensity. The luminosity at a distance of 3 kiloparsecs is (5.3 +- 1.3) x 10/sup 36/ ergs per second. The current shock velocity is 3400 +- 140 kilometers per second. An initial blast energy is found of 2.5 x 10/sup 51/ ergs and an average ambient density is found in the vicinity of Tycho of approximately 3 atoms per cubic centimeter. The mass swept up by the expanding shock wave is estimated at about 20 solar masses. A range of 0.3 to 3 solar masses has been placed on the supernova ejected mass.

Reid, P.B.

1982-01-01

434

X-ray free-electron lasers: Scientific goals and machine implications  

NASA Astrophysics Data System (ADS)

Free electron lasers are now being designed which will operate at wavelengths down to about 1. [1] The physics of the high-gain, single pass FEL process requires extremely bright electron pulses in the 10-20 GeV range. This electron brightness should be achievable using an RF-photocathode source and a linear accelerator, such as the initial acceleration stage of a TeV-range linear electron-positron collider. The x-ray FEL radiation produced will have unique properties. In particular: • The FEL peak intensity and peak brightness will be many orders of magnitude higher than can be produced by any other source. • The pulse length will be less than 1 picosecond, orders of magnitude shorter than can be achieved with any other bright source such as a synchrotron. • The FEL radiation will have full transverse coherence and a degeneracy parameter (photons/coherence volume) equal to 109 or more. No other source can produce hard x-radiation with a degeneracy parameter significantly greater than 1. These properties offer the chance to study chemical, biological, and condensed matter dynamical processes with sub-picosecond time resolution and angstrom spatial resolution. [2] The high peak power of the FEL radiation (greater than 1014 W/cm2) could be used to create precisely-controlled chemical and structural modifications inside samples. There is also the possibility that nonlinear x-ray interactions could be used to give increased resolution for spectroscopic studies, to greatly expand the parameter space for atomic physics studies, and to permit new fundamental tests of quantum mechanics. The exploration of these new x-ray techniques will require considerable development, not only in technical areas such as optics and detectors, but also in understanding the basic physics of the interaction of very intense x-radiation with matter. A large collaboration of US institutions is now conducting preliminary research and development in these areas, with the intention of creating an FEL operating at 1.5 in about the year 2006. [3] Germany also has a strong short-wavelength FEL research program, with a soft x-ray FEL under construction and a proposal for a future large facility based at the TESLA linear collider, [4] which would produce a variety of hard and soft x-ray laser beams. This work was supported by the US Department of Energy, Office of Basic Energy Sciences, under contract DE-AC03-76SF00515. .

Arthur, John

2001-07-01

435

X-ray analysis of nonMaxwellian distributions (current drive)  

SciTech Connect

The plasma bremsstrahlung emission is utilized to determine the shape of the electron velocity distribution in situations where it deviates strongly from a Maxwellian distribution. The instrumentation used to measure the hard x-ray emission is briefly discussed. Model calculations show that polarization measurements give best results for unrelativistic tails with tail temperatures T/sub b/ < 50 keV, whereas measurements of the angular distribution of the x-ray emission based on the forward scattering of bremsstrahlung for relativistic electrons yields the best information for T/sub b/ > 50 keV. The techniques were originally developed in order to analyze runaway discharges. Recently, they found new interest because of the formation of energetic electron tails during current drive. The first x-ray results from the current drive during LH heating on PLT are discussed.

von Goeler, S.; Stevens, J.; Stodiek, W.

1983-06-01

436

Radiological characterization and water equivalency of genipin gel for x-ray and electron beam dosimetry.  

PubMed

The genipin radiochromic gel offers enormous potential as a three-dimensional dosimeter in advanced radiotherapy techniques. We have used several methods (including Monte Carlo simulation), to investigate the water equivalency of genipin gel by characterizing its radiological properties, including mass and electron densities, photon interaction cross sections, mass energy absorption coefficient, effective atomic number, collisional, radiative and total mass stopping powers and electron mass scattering power. Depth doses were also calculated for clinical kilovoltage and megavoltage x-ray beams as well as megavoltage electron beams. The mass density, electron density and effective atomic number of genipin were found to differ from water by less than 2%. For energies below 150 keV, photoelectric absorption cross sections are more than 3% higher than water due to the strong dependence on atomic number. Compton scattering and pair production interaction cross sections for genipin gel differ from water by less than 1%. The mass energy absorption coefficient is approximately 3% higher than water for energies <60 keV due to the dominance of photoelectric absorption in this energy range. The electron mass stopping power and mass scattering power differ from water by approximately 0.3%. X-ray depth dose curves for genipin gel agree to within 1% with those for water. Our results demonstrate that genipin gel can be considered water equivalent for kilovoltage and megavoltage x-ray beam dosimetry. For megavoltage electron beam dosimetry, however, our results suggest that a correction factor may be needed to convert measured dose in genipin gel to that of water, since differences in some radiological properties of up to 3% compared to water are observed. Our results indicate that genipin gel exhibits greater water equivalency than polymer gels and PRESAGE formulations. PMID:21734335

Gorjiara, Tina; Hill, Robin; Kuncic, Zdenka; Bosi, Stephen; Davies, Justin B; Baldock, Clive

2011-07-06

437

Pressure-dependent electronic structures and orbital hybridization of Mn 3d states in multiferroic BiMnO3 : A combined x-ray absorption, x-ray emission, and resonant x-ray emission study  

NASA Astrophysics Data System (ADS)

We investigated both the dependence of electronic structures and spin states on pressure up to 25 GPa and the hybridization of Mn 3d states in BiMnO3 by combining measurements of x-ray absorption, x-ray emission, and 1s3p-resonant x-ray emission spectroscopy (RXES). The Mn K-edge x-ray absorption spectra of BiMnO3 show a great change for pressure ˜1 GPa, corresponding to the occurrence of a structural transition. The gradually diminished shoulder of the white line and subsequently increased intensity of the white line of Mn K-edge spectra on increasing the external pressure from 2 to ˜15 GPa are attributed to a diminished Jahn-Teller distortion of MnO6 octahedra in BiMnO3 with increasing pressure. For pressure >˜15 GPa, the intensity of the white line in Mn K-edge spectra of BiMnO3 became progressively decreased. Preedge peaks in Mn K-edge spectra of BiMnO3 at P = 25 GPa shifted to smaller energy ˜0.3 eV relative to P = 0.7 GPa. The spin magnetic moments deduced from the K? emission line show a significant decrease for pressures between 0 and 2 GPa, then a monotonic decrease for pressures between 2 and 7 GPa, and a slight decrease after 7 GPa. The 1s3p-RXES spectra obtained at the Mn-K preedge for BiMnO3 reveal that the empty Mn 3d(eg0) states exhibit a delocalized character, suggested to originate from the hybridization of the unoccupied Mn 3d states with the Mn 4p orbitals. These findings provide insight into the evolution of electronic structures related to the structural transformation of multiferroic BiMnO3 under pressure.

Chen, J. M.; Haw, S. C.; Lee, J. M.; Chen, S. A.; Lu, K. T.; Chen, S. W.; Deng, M. J.; Liao, Y.-F.; Lin, J. M.; Chen, B. H.; Chou, F. C.; Hiraoka, N.; Ishii, H.; Tsuei, K. D.; Huang, Eugene

2012-07-01

438

Synchrotron radiation based micro X-ray fluorescence analysis of the calibration samples used in surface sensitive total reflection and grazing emission X-ray fluorescence techniques  

NASA Astrophysics Data System (ADS)

Total reflection X-ray fluorescence (TXRF) and grazing emission X-ray fluorescence (GEXRF) are surface sensitive techniques and can be used for detailed surface studies of different materials, including ultra-low concentration contamination or the lateral and depth distributions of elements. The calibration procedure typically used involves placing a micro-droplet (˜?l) of the standard solution onto a silicon wafer (or quartz backing). After evaporation of the solvent, the residual amount of elements is used as a reference standard. Knowledge of the distribution of residue material on the substrate surface is crucial for precise quantification. In the present work the investigation of the lateral distribution of elements in the multielemental calibrating samples, containing the 23 most commonly studied elements, by using the synchrotron radiation based micro X-ray fluorescence is presented. The goal of this project was the study of a uniformity of the elemental distributions and determination of the residual elements morphology depending on the temperature of the drying process. The X-ray images were compared with optical and SEM images. Paper presents in details the experimental setup, sample preparation procedures, measurements and results. In the analysis of the X-ray images of the sample dried in high temperature the censoring approach was applied improving the quality of statistical analysis. The information on the elements distribution in the calibrating samples can be useful for developing more accurate calibration procedures applied in quantitative analysis of surface sensitive TXRF and GEXRF techniques.

Kubala-Kuku?, A.; Bana?, D.; Pajek, M.; Szlachetko, J.; Jagodzi?ski, P.; Susini, J.; Salomé, M.

2013-12-01

439

Idiopathic calcinosis of the scrotum: Scanning electron microscopic study with x-ray microanalysis  

Microsoft Academic Search

In a 31-year-old man 12 nodules up to 1 cm in diameter were observed in the scrotum; these had developed over 3 years. Energy-dispersive x-ray analysis of the dermal foci showed a high content of calcium and phosphorus even in nodules smaller than 1 mm in diameter. No increased mineral deposition was observed in the surrounding connective tissue, however. Scanning

L. H. Fuezesi; Günter Hollweg; Willy Lagrange; Christian Mittermayer

1991-01-01

440

Transmission Electron Microscopy and X-Ray Diffraction Analysis of Aluminum-Induced Crystallization of Amorphous Silicon in [alpha]-Si:H/Al and Al/[alpha]-Si:H Structures  

NASA Astrophysics Data System (ADS)

Solid phase crystallization of plasma-enhanced chemical-vapor-deposited (PECVD) amorphous silicon ([alpha]-Si:H) in [alpha]-Si:H/Al and Al/[alpha]-Si:H structures has been investigated using transmission electron microscopy (TEM) and X-ray diffraction (XRD). Radiative heating has been used to anneal films deposited on carbon-coated nickel (Ni) grids at temperatures between 200 and 400°C for TEM studies. [alpha]-Si:H films were deposited on c-Si substrates using high vacuum (HV) PECVD for the XRD studies. TEM studies show that crystallization of [alpha]-Si:H occurs at 200°C when Al film is deposited on top of the [alpha]-Si:H film. Similar behavior was observed in the XRD studies. In the case of [alpha]-Si:H deposited on top of Al films, the crystallization could not be observed at 400°C by TEM and even up to 500°C as seen by XRD.

Kishore, Ram; Hotz, C.; Naseem, H. A.; Brown, W. D.

2005-04-01