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Sample records for broadband x-ray spectra

  1. Broadband X-ray spectra of the ultraluminous x-ray source Holmberg IX X-1 observed with NuSTAR, XMM-Newton, and Suzaku

    DEFF Research Database (Denmark)

    Walton, D. J.; Harrison, F. A.; Grefenstette, B. W.;

    2014-01-01

    We present results from the coordinated broadband X-ray observations of the extreme ultraluminous X-ray source Holmberg IX X-1 performed by NuSTAR, XMM-Newton, and Suzaku in late 2012. These observations provide the first high-quality spectra of Holmberg IX X-1 above 10 keV to date, extending the X...

  2. The Broadband XMM-Newton and NuSTAR X-Ray Spectra of Two Ultraluminous X-Ray Sources in the Galaxy IC 342

    Science.gov (United States)

    Rana, Vikram; Harrison, Fiona A.; Bachetti, Matteo; Walton, Dominic J.; Furst, Felix; Barret, Didier; Miller, Jon M.; Fabian, Andrew C.; Boggs, Steven E.; Christensen, Finn C.; Craig, William W.; Grefenstette, Brian W.; Hailey, Charles J.; Madsen, Kristin K.; Ptak, Andrew F.; Stern, Daniel; Webb, Natalie A.; Zhang, William W.

    2015-02-01

    We present results for two ultraluminous X-ray sources (ULXs), IC 342 X-1 and IC 342 X-2, using two epochs of XMM-Newton and NuSTAR observations separated by ~7 days. We observe little spectral or flux variability above 1 keV between epochs, with unabsorbed 0.3-30 keV luminosities being 1.04+0.08-0.06 × 1040 erg s-1 for IC 342 X-1 and 7.40 ± 0.20 × 1039 erg s-1 for IC 342 X-2, so that both were observed in a similar, luminous state. Both sources have a high absorbing column in excess of the Galactic value. Neither source has a spectrum consistent with a black hole binary in low/hard state, and both ULXs exhibit strong curvature in their broadband X-ray spectra. This curvature rules out models that invoke a simple reflection-dominated spectrum with a broadened iron line and no cutoff in the illuminating power-law continuum. X-ray spectrum of IC 342 X-1 can be characterized by a soft disk-like blackbody component at low energies and a cool, optically thick Comptonization continuum at high energies, but unique physical interpretation of the spectral components remains challenging. The broadband spectrum of IC 342 X-2 can be fit by either a hot (3.8 keV) accretion disk or a Comptonized continuum with no indication of a seed photon population. Although the seed photon component may be masked by soft excess emission unlikely to be associated with the binary system, combined with the high absorption column, it is more plausible that the broadband X-ray emission arises from a simple thin blackbody disk component. Secure identification of the origin of the spectral components in these sources will likely require broadband spectral variability studies.

  3. Broadband X-ray Spectra of the Ultraluminoux X-ray Source Holmberg IX X-1 observed with NuSTAR, XMM-Newton and Suzaku

    CERN Document Server

    Walton, D J; Grefenstette, B W; Miller, J M; Bachetti, M; Barret, D; Boggs, S E; Christensen, F E; Craig, W W; Fabian, A C; Fuerst, F; Hailey, C J; Madsen, K K; Parker, M L; Ptak, A; Rana, V; Stern, D; Webb, N A; Zhang, W W

    2014-01-01

    We present results from the coordinated broadband X-ray observations of the extreme ultraluminous X-ray source Holmberg IX X-1 performed by NuSTAR, XMM-Newton and Suzaku in late 2012. These observations provide the first high-quality spectra of Holmberg IX X-1 above 10 keV to date, extending the X-ray coverage of this remarkable source up to ~30 keV. Broadband observations were undertaken at two epochs, between which Holmberg IX X-1 exhibited both flux and strong spectral variability, increasing in luminosity from Lx = (1.94+/-0.03)e40 erg/s to Lx = (3.38+/-0.03)e40 erg/s. Neither epoch exhibits a spectrum consistent with emission from the standard low/hard accretion state seen in Galactic black hole binaries, that would have been expected if Holmberg IX X-1 harbors a truly massive black hole accreting at substantially sub-Eddington accretion rates. The NuSTAR data confirm that the curvature observed previously in the 3-10 keV bandpass does represent a true spectral cutoff. During each epoch, the spectrum app...

  4. THE BROADBAND XMM-NEWTON AND NuSTAR X-RAY SPECTRA OF TWO ULTRALUMINOUS X-RAY SOURCES IN THE GALAXY IC 342

    Energy Technology Data Exchange (ETDEWEB)

    Rana, Vikram; Harrison, Fiona A.; Walton, Dominic J.; Furst, Felix; Grefenstette, Brian W.; Madsen, Kristin K. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Bachetti, Matteo; Barret, Didier; Webb, Natalie A. [Université de Toulouse, UPS-OMP, IRAP, Toulouse (France); Miller, Jon M. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042 (United States); Fabian, Andrew C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Boggs, Steven E.; Craig, William W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Christensen, Finn C. [DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Hailey, Charles J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Ptak, Andrew F.; Zhang, William W. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

    2015-02-01

    We present results for two ultraluminous X-ray sources (ULXs), IC 342 X-1 and IC 342 X-2, using two epochs of XMM-Newton and NuSTAR observations separated by ∼7 days. We observe little spectral or flux variability above 1 keV between epochs, with unabsorbed 0.3-30 keV luminosities being 1.04{sub −0.06}{sup +0.08}×10{sup 40} erg s{sup –1} for IC 342 X-1 and 7.40 ± 0.20 × 10{sup 39} erg s{sup –1} for IC 342 X-2, so that both were observed in a similar, luminous state. Both sources have a high absorbing column in excess of the Galactic value. Neither source has a spectrum consistent with a black hole binary in low/hard state, and both ULXs exhibit strong curvature in their broadband X-ray spectra. This curvature rules out models that invoke a simple reflection-dominated spectrum with a broadened iron line and no cutoff in the illuminating power-law continuum. X-ray spectrum of IC 342 X-1 can be characterized by a soft disk-like blackbody component at low energies and a cool, optically thick Comptonization continuum at high energies, but unique physical interpretation of the spectral components remains challenging. The broadband spectrum of IC 342 X-2 can be fit by either a hot (3.8 keV) accretion disk or a Comptonized continuum with no indication of a seed photon population. Although the seed photon component may be masked by soft excess emission unlikely to be associated with the binary system, combined with the high absorption column, it is more plausible that the broadband X-ray emission arises from a simple thin blackbody disk component. Secure identification of the origin of the spectral components in these sources will likely require broadband spectral variability studies.

  5. The Broadband XMM-Newton and NuSTAR X-ray Spectra of Two Ultraluminous X-ray Sources in the Galaxy IC 342

    DEFF Research Database (Denmark)

    Rana, Vikram; Harrison, Fiona A.; Bachetti, Matteo

    2015-01-01

    We present results for two Ultraluminous X-ray Sources (ULXs), IC 342 X-1 and IC 342 X-2, using two epochs of XMM-Newton and NuSTAR observations separated by ∼7 days. We observe little spectral or flux variability above 1 keV between epochs, with unabsorbed 0.3-30 keV luminosities being $1.......04+0.08/-0.06 x 1040 erg s-1 for IC 342 X-1 and 7.40±0.20 x 1039 erg s-1for IC 342 X-2, so that both were observed in a similar, luminous state. Both sources have a high absorbing column in excess of the Galactic value. Neither source has a spectrum consistent with a black hole binary in low/hard state, and both...... ULXs exhibit strong curvature in their broadband X-ray spectra. This curvature rules out models that invoke a simple reflection-dominated spectrum with a broadened iron line and no cutoff in the illuminating power-law continuum. X-ray spectrum of IC 342 X-1 can be characterized by a soft disk...

  6. X-Ray Emitting GHz-Peaked Spectrum Galaxies: Testing a Dynamical-Radiative Model with Broad-Band Spectra

    Energy Technology Data Exchange (ETDEWEB)

    Ostorero, L.; /Turin U. /INFN, Turin; Moderski, R.; /Warsaw, Copernicus Astron. Ctr. /KIPAC, Menlo Park; Stawarz, L.; /KIPAC, Menlo Park /Jagiellonian U., Astron. Observ.; Diaferio, A.; /Turin U. /INFN, Turin; Kowalska, I.; /Warsaw U. Observ.; Cheung, C.C.; /NASA, Goddard /Naval Research Lab, Wash., D.C.; Kataoka, J.; /Waseda U., RISE; Begelman, M.C.; /JILA, Boulder; Wagner, S.J.; /Heidelberg Observ.

    2010-06-07

    In a dynamical-radiative model we recently developed to describe the physics of compact, GHz-Peaked-Spectrum (GPS) sources, the relativistic jets propagate across the inner, kpc-sized region of the host galaxy, while the electron population of the expanding lobes evolves and emits synchrotron and inverse-Compton (IC) radiation. Interstellar-medium gas clouds engulfed by the expanding lobes, and photoionized by the active nucleus, are responsible for the radio spectral turnover through free-free absorption (FFA) of the synchrotron photons. The model provides a description of the evolution of the GPS spectral energy distribution (SED) with the source expansion, predicting significant and complex high-energy emission, from the X-ray to the {gamma}-ray frequency domain. Here, we test this model with the broad-band SEDs of a sample of eleven X-ray emitting GPS galaxies with Compact-Symmetric-Object (CSO) morphology, and show that: (i) the shape of the radio continuum at frequencies lower than the spectral turnover is indeed well accounted for by the FFA mechanism; (ii) the observed X-ray spectra can be interpreted as non-thermal radiation produced via IC scattering of the local radiation fields off the lobe particles, providing a viable alternative to the thermal, accretion-disk dominated scenario. We also show that the relation between the hydrogen column densities derived from the X-ray (N{sub H}) and radio (N{sub HI}) data of the sources is suggestive of a positive correlation, which, if confirmed by future observations, would provide further support to our scenario of high-energy emitting lobes.

  7. The Broadband XMM-Newton and NuSTAR X-ray Spectra of Two Ultraluminous X-ray Sources in the Galaxy IC 342

    CERN Document Server

    Rana, Vikram; Bachetti, Matteo; Walton, Dominic J; Furst, Felix; Barret, Didier; Miller, Jon M; Fabian, Andrew C; Boggs, Steven E; Christensen, Finn C; Craig, William W; Grefenstette, Brian W; Hailey, Charles J; Madsen, Kristin K; Ptak, Andrew F; Stern, Daniel; Webb, Natalie A; Zhang, William W

    2014-01-01

    We present XMM-Newton and NuSTAR observations of two ultraluminous X-ray sources in the nearby galaxy IC 342. The observations were carried out in two epochs separated by ~7 days, with each having an approximate exposure time of ~40 ks (XMM-Newton) and ~100 ks (NuSTAR). We observe little spectral or flux variability above 1 keV between epochs, with unabsorbed 0.3--30 keV luminosities being $1.04^{+0.08}_{-0.06} \\times 10^{40}$ erg s$^{-1}$ for IC 342 X-1 and $7.40\\pm0.20 \\times 10^{39}$ erg s$^{-1}$ for IC 342 X-2. IC 342 X-2 shows a highly variable component prominent below 1 keV that cannot be explained by blackbody or thermal plasma emission. With the broad bandpass of these observations we can demonstrate conclusively for the first time that both objects have a clear spectral turnover above ~8 keV. Neither source is consistent with a black hole binary in a low/hard state, and a simple reflection-dominated spectrum with a broadened iron line and no cutoff in the illuminating power-law continuum can be rule...

  8. Broad-band hard X-ray reflectors

    DEFF Research Database (Denmark)

    Joensen, K.D.; Gorenstein, P.; Hoghoj, P.

    1997-01-01

    of the multilayer is found to agree extraordinarily well with theory (assuming an interface roughness of 4.5 Angstrom), while the agreement for the gold film is less, The overall performance of the supermirror is superior to that of gold, extending the band of reflection at least a factor of 2.8 beyond......Interest in optics for hard X-ray broad-band application is growing. In this paper, we compare the hard X-ray (20-100 keV) reflectivity obtained with an energy-dispersive reflectometer, of a standard commercial gold thin-film with that of a 600 bilayer W/Si X-ray supermirror. The reflectivity...... that of the gold, Various other design options are discussed, and we conclude that continued interest in the X-ray supermirror for broad-band hard X-ray applications is warranted....

  9. The broad-band X-ray spectrum of Cygnus X-2

    Science.gov (United States)

    Pravdo, S. H.

    1983-01-01

    Cygnus X-2 was observed with the broad-band X-ray spectroscopy experiment, HEAO 1 A-2, in the energy range 0.4-18 keV for four intervals of approximately 31 s over the course of 5 days in 1977. The spectra can be adequately represented by single-temperature thermal bremmstrahlung continua with temperatures ranging from 3.7 x 10 to the 7th K to 6.4 x 10 to the 7th K. An examination of the spectra and the spectra-luminosity relationship effectively rules out one degenerate dwarf model for the X-ray emission. The far-UV continuum emission could be dominated by this continuum component during X-ray high states, an effect which would be detected in optical UV line observations. A Comptonized X-ray cloud around a neutron star remains a viable model for the observed X-ray spectra.

  10. A Soft X-ray Polarimeter Designed for Broad-band X-ray Telescopes

    CERN Document Server

    Marshall, Herman L

    2007-01-01

    A novel approach for measuring linear X-ray polarization over a broad-band using conventional imaging optics and cameras is described. A new type of high efficiency grating, called the critical angle transmission grating is used to disperse soft X-rays radially from the telescope axis. A set of multilayer-coated paraboloids re-image the dispersed X-rays to rings in the focal plane. The intensity variation around these rings is measured to determine three Stokes parameters: I, Q, and U. By laterally grading the multilayer optics and matching the dispersion of the gratings, one may take advantage of high multilayer reflectivities and achieve modulation factors over 50% over the entire 0.2 to 0.8 keV band. A sample design is shown that could be used with the Constellation-X optics.

  11. The broad-band X-ray spectra of Mrk 926, 4U 1344-60 and ESO 141-G055

    Science.gov (United States)

    Lohfink, Anne; Fabian, Andrew C.; Buisson, Douglas; Kara, Erin; Reynolds, Christopher S.

    2017-08-01

    Mrk 926, 4U 1344-60 and ESO 141-G055 are bright Seyfert 1 galaxies that contrary to many of the Seyfert 1s studied in-depth with NuSTAR do not show signs of relativistic reflection. We present results from the spectroscopic analyses of simultaneous Swift-NuSTAR or in case of Mrk 926 XMM-NuSTAR observations of these three AGN. The broad-band spectral coverage and the simplicity of the spectra allows us to measure the primary emission with great accuracy. We use the results from our spectral studies and others in the literature to explore whether the differences in reflection-strength in bright Seyfert 1s coincide with any differences in the Comptonization parameters. This allows us to test the hypothesis that the detection of a relativistic reflection component is geometry-driven.

  12. Measuring the angular dependence of betatron x-ray spectra in a laser-wakefield accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Albert, F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pollock, B. B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Shaw, J. L. [Univ. of California, Los Angeles, CA (United States); Marsh, K. A. [Univ. of California, Los Angeles, CA (United States); Ralph, J. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chen, Y. -H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Alessi, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pak, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Clayton, C. E. [Univ. of California, Los Angeles, CA (United States); Glenzer, S. H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Joshi, C. [Univ. of California, Los Angeles, CA (United States)

    2014-07-22

    This paper presents a new technique to measure the angular dependence of betatron x-ray spectra in a laser-wakefield accelerator. Measurements are performed with a stacked image plates spectrometer, capable of detecting broadband x-ray radiation up to 1 MeV. It can provide measurements of the betatron x-ray spectrum at any angle of observation (within a 40 mrad cone) and of the beam profile. A detailed description of our data analysis is given, along with comparison for several shots. As a result, these measurements provide useful information on the dynamics of the electrons are they are accelerated and wiggled by the wakefield.

  13. Compton spectra of atoms at high x-ray intensity

    Science.gov (United States)

    Son, Sang-Kil; Geffert, Otfried; Santra, Robin

    2017-03-01

    Compton scattering is the nonresonant inelastic scattering of an x-ray photon by an electron and has been used to probe the electron momentum distribution in gas-phase and condensed-matter samples. In the low x-ray intensity regime, Compton scattering from atoms dominantly comes from bound electrons in neutral atoms, neglecting contributions from bound electrons in ions and free (ionized) electrons. In contrast, in the high x-ray intensity regime, the sample experiences severe ionization via x-ray multiphoton multiple ionization dynamics. Thus, it becomes necessary to take into account all the contributions to the Compton scattering signal when atoms are exposed to high-intensity x-ray pulses provided by x-ray free-electron lasers (XFELs). In this paper, we investigate the Compton spectra of atoms at high x-ray intensity, using an extension of the integrated x-ray atomic physics toolkit, xatom. As the x-ray fluence increases, there is a significant contribution from ionized electrons to the Compton spectra, which gives rise to strong deviations from the Compton spectra of neutral atoms. The present study provides not only understanding of the fundamental XFEL-matter interaction but also crucial information for single-particle imaging experiments, where Compton scattering is no longer negligible. , which features invited work from the best early-career researchers working within the scope of J. Phys. B. This project is part of the Journal of Physics series’ 50th anniversary celebrations in 2017. Sang-Kil Son was selected by the Editorial Board of J. Phys. B as an Emerging Leader.

  14. High-resolution x-ray photoemission spectra of silver

    DEFF Research Database (Denmark)

    Barrie, A.; Christensen, N. E.

    1976-01-01

    An electron spectrometer fitted with an x-ray monochromator for Al Kα1,2 radiation (1486.6 eV) has been used to record high-resolution x-ray photoelectron spectra for the 4d valence band as well as the 3d spin doublet in silver. The core-level spectrum has a line shape that can be described...

  15. X-ray absorption spectra of plasmas

    Institute of Scientific and Technical Information of China (English)

    PENG; Yonglun彭永伦; HAN; Xiaoying韩小英; LI; Jiaming李家明; DING; Yaonan丁耀南; YANG; Jiamin杨家敏; ZHENG; Zhijian郑志坚

    2002-01-01

    In this paper we present a theoretical method to calculate the absorption spectra of hot dense plasmas. Based on our fully relativistic treatment incorporated with the quantum defect theory to handle the huge number of transition arrays from many configurations with high principal quantum number, we can calculate the absorption spectra for any element or multi-element plasmas with little computational efforts. We calculate the absorption spectra of C10H1605 plasmas, which are in good agreement with the experimental spectra. We can then provide diagnostic analysis for plasmas in relevant inertial confinement fusion (lCF) experiments; namely not only to determine plasmas' temperatures and densities, but also to provide the population densities of various ionic stages. Our theoretical method verified by "benchmark experiments" will be a basic tool to provide "precise" opacity data for the ICF research.``

  16. A ubiquitous absorption feature in the X-ray spectra of BL Lacertae objects

    Science.gov (United States)

    Madejski, Greg M.; Mushotzky, Richard F.; Weaver, Kimberly A.; Arnaud, Keith A.; Urry, C. Megan

    1991-01-01

    The paper presents the broadband (0.5-20-keV) X-ray spectra of five X-ray bright BL Lac objects observed with the Einstein Observatory Solid State Spectrometer (SSS) and Monitor Proportional Counter (MPC) detectors. The combination of moderate energy resolution and broad spectral coverage makes it possible to confirm the presence of an absorption feature at an energy of 650 eV in the BL Lac object PKS 2155-304, originally reported by Canizares and Kruper (1984) based on higher resolution Einstein Objective Grating Spectrometer (OGS) data.

  17. Broadband, monochromatic and quasi-monochromatic x-ray propagation in multi-Z media for imaging and diagnostics

    Science.gov (United States)

    Westphal, Maximillian S.; Lim, Sara N.; Nahar, Sultana N.; Chowdhury, Enam; Pradhan, Anil K.

    2017-08-01

    With the advent of monochromatic and quasi-monochromatic x-ray sources, we explore their potential with computational and experimental studies on propagation through a combination of low and high-Z (atomic number) media for applications to imaging and detection. The multi-purpose code GEANT4 and a new code PHOTX are employed in numerical simulations, and a variety of x-ray sources are considered: conventional broadband devices with well-known spectra, quasi-monochromatic laser driven sources, and monochromatic synchrotron x-rays. Phantom samples consisting of layers of low-Z and high-Z material are utilized, with atomic-molecular species ranging from H2O to gold. Differential and total attenuation of x-ray fluxes from the different x-ray sources are illustrated through simulated x-ray images. Main conclusions of this study are: I. It is shown that a 65 keV Gaussian quasi-monochromatic source is capable of better contrast with less radiation exposure than a common 120 kV broadband simulator. II. A quantitative measure is defined and computed as a metric to compare the efficacy of any two x-ray sources, as a function of concentration of high-Z moieties in predominantly low-Z environment and depth of penetration. III. Characteristic spectral features of \

  18. Analyzing the Spectra of Accreting X-Ray Pulsars

    Science.gov (United States)

    Wolff, Michael

    This proposal seeks funding for the analysis of accretion-powered X-ray pulsar spectra from NASA/ HEASARC archived X-ray data. Spectral modeling of accreting X-ray pulsars can tell us a great deal about the physical conditions in and near high mass X-ray binary systems. Such systems have accretion flows where plasma is initially channeled from an accretion disk by the strong neutron star magnetic field, eventually falling onto the magnetic polar cap of the neutron star compact object. Many of these accreting X-ray pulsars have X-ray spectra that consist of broad power-law continua with superposed cyclotron resonant scattering features indicating magnetic field strengths above 10^12 G. The energies of these cyclotron line features have recently been shown to vary with X-ray luminosity in a number of sources such as Her X-1 and V 0332+53, a phenomenon not well understood. Another recent development is the relatively new analytic model for the spectral continuum formation in accretion-powered pulsar systems developed by Becker & Wolff. In their formalism the accretion flows are assumed to go through radiation- dominated radiative shocks and settle onto the neutron star surface. The radiation field consists of strongly Comptonized bremsstrahlung emission from the entire plasma, Comptonized cyclotron emission from the de-excitations of Landau-excited electrons in the neutron star magnetic field, and Comptonized black-body emission from a thermal mound near the neutron star surface. We seek to develop the data analysis tools to apply this model framework to the X-ray data from a wide set of sources to make progress characterizing the basic accretion properties (e.g., magnetic field strength, plasma temperatures, polar cap size, accretion rate per unit area, dominance of bulk vs. thermal Comptonization) as well as understanding the variations of the cyclotron line energies with X-ray luminosity. The three major goals of our proposed work are as follows: In the first year

  19. Unfolding X-ray spectra using a flat panel detector.

    Science.gov (United States)

    Gallardo, Sergio; Juste, Belén; Pozuelo, Fausto; Ródenas, José; Querol, Andrea; Verdú, Gumersindo

    2013-01-01

    It is difficult to measure the energy spectrum of X-ray tubes due to the pile up effect produced by the high fluence of photons. Using attenuating materials, appropriate detector devices and the Monte Carlo method, primary X-ray spectrum of these devices can be estimated. In this work, a flat panel detector with a PMMA wedge has been used to obtain a dose curve corresponding to certain working conditions of a radiodiagnostic X-ray tube. The relation between the dose curve recorded by the flat panel and the primary X-ray spectrum is defined by a response function. Normally this function can be approximated by a matrix, which can be obtained by means of the Monte Carlo method. Knowing the measured dose curve and the response matrix, the primary X-ray spectrum can be unfolded. However, there are some problems that strongly affect the applicability of this method: i.e. technical features of the flat panel and inherent characteristics of the involved radiation physics (ill-posed problem). Both aspects are analyzed in this work, concluding that the proposed method can be applied with an acceptable accuracy for spectra without characteristic lines, for instance, tungsten anode in the 50-70 kVp range.

  20. Relativistic Effects on Reflection X-ray Spectra of AGN

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Khee-Gan; /University Coll. London; Fuerst, Steven V.; /KIPAC, Menlo Park; Brandwardi-Raymond, Graziella; Wu, Kinwah; Crowley, Oliver; /University Coll. London

    2007-01-05

    We have calculated the reflection component of the X-ray spectra of active galactic nuclei (AGN) and shown that they can be significantly modified by the relativistic motion of the accretion flow and various gravitational effects of the central black hole. The absorption edges in the reflection spectra suffer severe energy shifts and smearing. The degree of distortion depends on the system parameters, and the dependence is stronger for some parameters such as the inner radius of the accretion disk and the disk viewing inclination angles. The relativistic effects are significant and are observable. Improper treatment of the reflection component of the X-ray continuum in spectral fittings will give rise to spurious line-like features, which will mimic the fluorescent emission lines and mask the relativistic signatures of the lines.

  1. Chemical Speciation via X-ray Emission Spectra

    Science.gov (United States)

    Ankudinov, A. L.; Rehr, J. J.; Elam, W. T.; Sieber, J. R.

    2002-03-01

    We have extended our calculations of lineshapes in x-ray emission and x-ray fluorescence (XRF) spectroscopy to investigate the dependence on formal oxidation state. We used the self-consistent x-ray spectroscopy code FEFF8.1 [1], which is based on a real-space Green's function formalism, to calculate the phosphorus K-M_2,3 line and the Cr K and L emission lines for a range of simple oxides. These lines exhibit changes depending on oxidation state. Convolution with an algorithm describing the response function of the spectrometer is necessary to compare to experimental measurements. The calculated spectra are compared to measured spectra and to other relevant calculations, e.g., Fujikawa and Kawai [2]. The comparisons thus far indicate that calculations and measurements together can yield a quantitative analysis of compounds. [1] A. L. Ankudinov and J. J. Rehr, Phys. Rev. B 62, 2437 (2000). [2] T. Fujikawa and J. Kawai, J. Phys. Soc. Japan 68, 4032 (1999).

  2. Utilizing broadband X-rays in a Bragg coherent X-ray diffraction imaging experiment

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Wonsuk; Liu, Wenjun; Harder, Ross; Xu, Ruqing; Fuoss, Paul H.; Hruszkewycz, Stephan O.

    2016-07-26

    A method is presented to simplify Bragg coherent X-ray diffraction imaging studies of complex heterogeneous crystalline materials with a two-stage screening/imaging process that utilizes polychromatic and monochromatic coherent X-rays and is compatible within situsample environments. Coherent white-beam diffraction is used to identify an individual crystal particle or grain that displays desired properties within a larger population. A three-dimensional reciprocal-space map suitable for diffraction imaging is then measured for the Bragg peak of interest using a monochromatic beam energy scan that requires no sample motion, thus simplifyingin situchamber design. This approach was demonstrated with Au nanoparticles and will enable, for example, individual grains in a polycrystalline material of specific orientation to be selected, then imaged in three dimensions while under load.

  3. Utilizing broadband X-rays in a Bragg coherent X-ray diffraction imaging experiment.

    Science.gov (United States)

    Cha, Wonsuk; Liu, Wenjun; Harder, Ross; Xu, Ruqing; Fuoss, Paul H; Hruszkewycz, Stephan O

    2016-09-01

    A method is presented to simplify Bragg coherent X-ray diffraction imaging studies of complex heterogeneous crystalline materials with a two-stage screening/imaging process that utilizes polychromatic and monochromatic coherent X-rays and is compatible with in situ sample environments. Coherent white-beam diffraction is used to identify an individual crystal particle or grain that displays desired properties within a larger population. A three-dimensional reciprocal-space map suitable for diffraction imaging is then measured for the Bragg peak of interest using a monochromatic beam energy scan that requires no sample motion, thus simplifying in situ chamber design. This approach was demonstrated with Au nanoparticles and will enable, for example, individual grains in a polycrystalline material of specific orientation to be selected, then imaged in three dimensions while under load.

  4. Measuring x-ray spectra of flash radiographic sources

    Science.gov (United States)

    Gehring, Amanda E.; Espy, Michelle A.; Haines, Todd J.; Mendez, Jacob; Moir, David C.; Sedillo, Robert; Shurter, Roger P.; Volegov, Petr; Webb, Timothy J.

    2015-08-01

    A Compton spectrometer has been re-commissioned for measurements of flash radiographic sources. The determination of the energy spectrum of these sources is difficult due to the high count rates and short nature of the pulses (~50 ns). The spectrometer is a 300 kg neodymium-iron magnet which measures spectra in the <1 MeV to 20 MeV energy range. Incoming x-rays are collimated into a narrow beam incident on a converter foil. The ejected Compton electrons are collimated so that the forward-directed electrons enter the magnetic field region of the spectrometer. The position of the electrons at the magnet's focal plane is a function of their momentum, allowing the x-ray spectrum to be reconstructed. Recent measurements of flash sources are presented.

  5. The peculiar optical-UV X-ray spectra of the X-ray weak quasar PG 0043+039

    CERN Document Server

    Kollatschny, W; Zetzl, M; Santos-Lleó, M; Rodríguez-Pascual, P M; Ballo, L; Talavera, A

    2016-01-01

    The object PG 0043+039 has been identified as a broad absorption line (BAL) quasar based on its UV spectra. However, this optical luminous quasar has not been detected before in deep X-ray observations, making it the most extreme X-ray weak quasar known today. This study aims to detect PG 0043+039 in a deep X-ray exposure. The question is what causes the extreme X-ray weakness of PG 0043+039? Does PG 0043+039 show other spectral or continuum peculiarities? We took simultaneous deep X-ray spectra with XMM-Newton, far-ultraviolet (FUV) spectra with the Hubble Space Telescope (HST) and optical spectra of PG 0043+039 with the Hobby-Eberly Telescope (HET) and Southern African Large Telescope (SALT) in July, 2013. We have detected PG 0043+039 in our X-ray exposure taken in 2013. We presented our first results in a separate paper (Kollatschny et al. 2015). PG 0043+039 shows an extreme {\\alpha}_ox gradient ({\\alpha}_ox =-2.37). Furthermore, we were able to verify an X-ray flux of this source in a reanalysis of the X-...

  6. Broad-band X-ray observations of CIR X-1

    Science.gov (United States)

    Maisack, M.; Staubert, R.; Balucinska-Church, M.; Skinner, G.; Doebereiner, S.; Englhauser, J.; Aref'ev, V. A.; Efremov, V. V.; Sunyaev, R. A.

    1995-08-01

    We present broad-band (2-88 keV) X-ray observations of the X-ray binary Cir X-1 with the TTM and HEXE instruments on board of the Mir space station. The observations were made in January/February 1989. The spectrum is best described by a model with 3 components: a blackbody at low energies, an iron line and a Comptonized hard continuum. The spectrum is variable during our observations; when the Comptonized component becomes harder, the spectrum becomes softer below 15 keV. The high-energy spectrum resembles that of X-ray binary pulsars.

  7. X-ray-binary spectra in the lamp post model

    CERN Document Server

    Vincent, F H; Zdziarski, A A; Madej, J

    2016-01-01

    [Abridged] Context. The high-energy radiation from black-hole binaries may be due to the reprocessing of a lamp located on the black hole axis, emitting X-rays. The observed spectrum is made of 3 components: the direct spectrum; the thermal bump; and the reflected spectrum made of the Compton hump and the iron-line complex. Aims. We aim at computing accurately the complete reprocessed spectrum (thermal bump + reflected) of black-hole binaries over the entire X-ray band. We also determine the strength of the direct component. Our choice of parameters is adapted to a source showing an important thermal component. Methods. We compute in full GR the illumination of a thin disk by a lamp along the rotation axis. We use the ATM21 radiative transfer code to compute the spectrum emitted along the disk. We ray trace this local spectrum to determine the reprocessed spectrum as observed at infinity. We discuss the dependence of the local and ray-traced spectra on the emission angle and spin. Results. We show the importa...

  8. Broadband X-ray emission and the reality of the broad iron line from the Neutron Star - White Dwarf X-ray binary 4U 1820-30

    CERN Document Server

    Mondal, Aditya S; Pahari, Mayukh; Misra, Ranjeev; Kembhavi, Ajit K; Raychaudhuri, Biplab

    2016-01-01

    Broad relativistic iron lines from neutron star X-ray binaries are important probes of the inner accretion disk. The X-ray reflection features can be weakened due to strong magnetic fields or very low iron abundances such as is possible in X-ray binaries with low mass, first generation stars as companions. Here we investigate the reality of the broad iron line detected earlier from the neutron star low mass X-ray binary 4U~1820--30 with a degenerate helium dwarf companion. We perform a comprehensive, systematic broadband spectral study of the atoll source using \\suzaku{} and simultaneous \

  9. X-ray Flares of EV Lac: Statistics, Spectra, Diagnostics

    CERN Document Server

    Huenemoerder, David P; Testa, Paola; Drake, Jeremy J; Osten, Rachel A; Reale, Fabio

    2010-01-01

    We study the spectral and temporal behavior of X-ray flares from the active M-dwarf EV Lac in 200 ks of exposure with the Chandra/HETGS. We derive flare parameters by fitting an empirical function which characterizes the amplitude, shape, and scale. The flares range from very short (<1 ks) to long (10 ks) duration events with a range of shapes and amplitudes for all durations. We extract spectra for composite flares to study their mean evolution and to compare flares of different lengths. Evolution of spectral features in the density-temperature plane shows probable sustained heating. The short flares are significantly hotter than the longer flares. We determined an upper limit to the Fe K fluorescent flux, the best fit value being close to what is expected for compact loops.

  10. Comparison of hard X-ray spectra obtained by spectrometers on Hinotori and SMM and detection of 'superhot' component

    Science.gov (United States)

    Nitta, Nariaki

    1988-01-01

    Hard X-ray spectra in solar flares obtained by the broadband spectrometers aboard Hinotori and SMM are compared. Within the uncertainty brought about by assuming the typical energy of the background X-rays, spectra by the Hinotori spectrometer are usually consistent with those by the SMM spectrometer for flares in 1981. On the contrary, flares in 1982 persistently show 20-50-percent higher flux by Hinotori than by SMM. If this discrepancy is entirely attributable to errors in the calibration of energy ranges, the errors would be about 10 percent. Despite such a discrepancy in absolute flux, in the the decay phase of one flare, spectra revealed a hard X-ray component (probably a 'superhot' component) that could be explained neither by emission from a plasma at about 2 x 10 to the 7th K nor by a nonthermal power-law component. Imaging observations during this period show hard X-ray emission nearly cospatial with soft X-ray emission, in contrast with earlier times at which hard and soft X-rays come from different places.

  11. A broadband x-ray imaging spectroscopy with high-angular resolution: the FORCE mission

    Science.gov (United States)

    Mori, Koji; Tsuru, Takeshi Go; Nakazawa, Kazuhiro; Ueda, Yoshihiro; Okajima, Takashi; Murakami, Hiroshi; Awaki, Hisamitsu; Matsumoto, Hironori; Fukazawa, Yasushi; Tsunemi, Hiroshi; Takahashi, Tadayuki; Zhang, William W.

    2016-07-01

    We are proposing FORCE (Focusing On Relativistic universe and Cosmic Evolution) as a future Japan-lead Xray observatory to be launched in the mid 2020s. Hitomi (ASTRO-H) possesses a suite of sensitive instruments enabling the highest energy-resolution spectroscopy in soft X-ray band, a broadband X-ray imaging spectroscopy in soft and hard X-ray bands, and further high energy coverage up to soft gamma-ray band. FORCE is the direct successor to the broadband X-ray imaging spectroscopy aspect of Hitomi (ASTRO-H) with significantly higher angular resolution. The current design of FORCE defines energy band pass of 1-80 keV with angular resolution of black holes" in various mass-scales: "buried supermassive black holes (SMBHs)" (> 104 M⊙) residing in the center of galaxies in a cosmological distance, "intermediate-mass black holes" (102-104 M⊙) acting as the possible seeds from which SMBHs grow, and "orphan stellar-mass black holes" (mirror and wide-band X-ray detector. The focal length is currently planned to be 10 m. The silicon mirror with multi-layer coating is our primary choice to achieve lightweight, good angular optics. The detector is a descendant of hard X-ray imager onboard Hitomi (ASTRO-H) replacing its silicon strip detector with SOI-CMOS silicon pixel detector, allowing an extension of the low energy threshold down to 1 keV or even less.

  12. X-ray spectra of hot accretion flows

    CERN Document Server

    Niedzwiecki, Andrzej; Stepnik, Agnieszka

    2014-01-01

    We study radiative properties of hot accretion flows in a general relativistic model with an exact treatment of global Comptonization, developed in our recent works. We note a strong dependence of electron temperature on the strength of magnetic field and we clarify that the underlying mechanism involves the change of the flow structure, with more strongly magnetised flows approaching the slab geometry more closely. We find that the model with thermal synchrotron radiation being the main source of seed photons agrees with the spectral index vs Eddington ratio relation observed in black hole transients below 1 per cent of the Eddington luminosity, LEdd, and models with a weak direct heating of electrons (small delta) are more consistent with observations. Models with large delta predict slightly too soft spectra, furthermore, they strongly overpredict electron temperatures at ~0.01 LEdd. The low-luminosity spectra, at <0.001 LEdd, deviate from a power-law shape in the soft X-ray range and we note that the f...

  13. SUZAKU OBSERVATIONS OF γ-RAY BRIGHT RADIO GALAXIES: ORIGIN OF THE X-RAY EMISSION AND BROADBAND MODELING

    Energy Technology Data Exchange (ETDEWEB)

    Fukazawa, Yasushi; Itoh, Ryosuke; Tokuda, Shin' ya [Department of Physical Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Finke, Justin [U.S. Naval Research Laboratory, Code 7653, 4555 Overlook Avenue SW, Washington, DC 20375-5352 (United States); Stawarz, Łukasz [Institute of Space and Astronautical Science, JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Tanaka, Yasuyuki, E-mail: fukazawa@hep01.hepl.hiroshima-u.ac.jp [Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan)

    2015-01-10

    We performed a systematic X-ray study of eight nearby γ-ray bright radio galaxies with Suzaku in order to understand the origins of their X-ray emissions. The Suzaku spectra for five of those have been presented previously, while the remaining three (M87, PKS 0625–354, and 3C 78) are presented here for the first time. Based on the Fe-K line strength, X-ray variability, and X-ray power-law photon indices, and using additional information on the [O III] line emission, we argue for a jet origin of the observed X-ray emission in these three sources. We also analyzed five years of Fermi Large Area Telescope (LAT) GeV gamma-ray data on PKS 0625–354 and 3C 78 to understand these sources within the blazar paradigm. We found significant γ-ray variability in the former object. Overall, we note that the Suzaku spectra for both PKS 0625–354 and 3C 78 are rather soft, while the LAT spectra are unusually hard when compared with other γ-ray detected low-power (FR I) radio galaxies. We demonstrate that the constructed broadband spectral energy distributions of PKS 0625–354 and 3C 78 are well described by a one-zone synchrotron/synchrotron self-Compton model. The results of the modeling indicate lower bulk Lorentz factors compared to those typically found in other BL Lacertae (BL Lac) objects, but consistent with the values inferred from modeling other LAT-detected FR I radio galaxies. Interestingly, the modeling also implies very high peak (∼10{sup 16} Hz) synchrotron frequencies in the two analyzed sources, contrary to previously suggested scenarios for Fanaroff-Riley (FR) type I/BL Lac unification. We discuss the implications of our findings in the context of the FR I/BL Lac unification schemes.

  14. X-ray measurements on wood - spectra measurements

    DEFF Research Database (Denmark)

    Jensen, Signe Kamp; Thygesen, Lisbeth Garbrecht; Gerward, Leif

    (free-scanning). In this way 100 points are measured for each wood sample. This produces information about moisture content and density of the samples as water and wood attenuations of the x-rays are different for the different energy levels contained in the x-rays. The "real" density and moisture...

  15. Broadband x-ray properties of the gamma-ray binary 1FGL J1018.6-5856

    DEFF Research Database (Denmark)

    An, Hongjun; Bellm, Eric; Bhalerao, Varun

    2015-01-01

    We report on NuSTAR, XMM-Newton, and Swift observations of the gamma-ray binary 1FGL J1018.6-5856. We measure the orbital period to be 16.544 ± 0.008 days using Swift data spanning 1900 days. The orbital period is different from the 2011 gamma-ray measurement which was used in the previous X......, and that the broadband X-ray spectra measured with NuSTAR, XMM-Newton, and Swift are well fit with an unbroken power-law model. This spectrum suggests that the system may not be accretion-powered....

  16. A comprehensive analysis of the hard X-ray spectra of bright Seyfert galaxies

    Science.gov (United States)

    Lubiński, P.; Beckmann, V.; Gibaud, L.; Paltani, S.; Papadakis, I. E.; Ricci, C.; Soldi, S.; Türler, M.; Walter, R.; Zdziarski, A. A.

    2016-05-01

    Hard X-ray spectra of 28 bright Seyfert galaxies observed with INTEGRAL were analysed together with the X-ray spectra from XMM-Newton, Suzaku and RXTE. These broad-band data were fitted with a model assuming a thermal Comptonization as a primary continuum component. We tested several model options through a fitting of the Comptonized continuum accompanied by a complex absorption and a Compton reflection. Both the large data set used and the model space explored allowed us to accurately determine a mean temperature kTe of the electron plasma, the Compton parameter y and the Compton reflection strength R for the majority of objects in the sample. Our main finding is that a vast majority of the sample (20 objects) is characterized by kTe 200 keV. The median kTe for entire sample is 48_{-14}^{+57} keV. The distribution of the y parameter is bimodal, with a broad component centred at ≈0.8 and a narrow peak at ≈1.1. A complex, dual absorber model improved the fit for all data sets, compared to a simple absorption model, reducing the fitted strength of Compton reflection by a factor of about 2. Modest reflection (median R ≈ 0.32) together with a high ratio of Comptonized to seed photon fluxes point towards a geometry with a compact hard X-ray emitting region well separated from the accretion disc. Our results imply that the template Seyferts spectra used in the population synthesis models of active galactic nuclei (AGN) should be revised.

  17. X-ray spectra of hot accretion flows

    Science.gov (United States)

    Niedźwiecki, Andrzej; Xie, Fu-Guo; Stȩpnik, Agnieszka

    2014-09-01

    We study radiative properties of hot accretion flows in a general relativistic model with an exact treatment of global Comptonization, developed in our recent works. We note a strong dependence of electron temperature on the strength of magnetic field and we clarify that the underlying mechanism involves the change of the flow structure, with more strongly magnetized flows approaching the slab geometry more closely. We find that the model with thermal synchrotron radiation being the main source of seed photons agrees with the spectral index versus Eddington ratio relation observed in black hole transients below 1 per cent of the Eddington luminosity, LEdd, and models with a weak direct heating of electrons (small δ) are more consistent with observations. Models with large δ predict slightly too soft spectra, furthermore, they strongly overpredict electron temperatures at ˜0.01LEdd. The low-luminosity spectra, at ≲ 0.001LEdd, deviate from a power-law shape in the soft X-ray range, and we note that the first-scattering bump often resembles a thermal like component, with the temperature of a few hundred eV, superimposed on a power-law spectrum. The model with thermal Comptonization of thermal synchrotron radiation does not agree with well-studied AGNs observed below ˜0.01LEdd, for which there is a substantial evidence for the lack of an inner cold disc. This indicates that the model of hot flows powering AGNs should be revised, possibly by taking into account an additional (but internal to the flow) source of seed photons.

  18. What can we learn from EPIC X-ray spectra of Seyfert 1 galaxies?

    CERN Document Server

    Pounds, K; Pounds, Ken; Reeves, James

    2002-01-01

    The EPIC detectors on XMM-Newton provide the most sensitive broad band (0.3-12 keV) X-ray spectra to date. Observations of 6 Seyfert 1 galaxies, covering a wide luminosity range, are examined with the aim of identifying the primary X-ray continuum and constraining superimposed emission and absorption features. A soft excess emission component is seen in every case, but with a spectral form which differs markedly with luminosity across our sample. Current interpretations of the soft excess range from intrinsic thermal emission from the accretion disc to reprocessing of harder radiation absorbed in the disc skin. Visual examination of the broad-band EPIC spectra suggest that the luminosity trend in the observed spectral profiles may be governed primarily by differences in the line-of-sight absorption. In that case the underlying continuum could have a common form across the sample. Examination of spectral features in the Fe K band confirm the common presence of a narrow emission line at 6.4 keV. Modelling of th...

  19. A comprehensive analysis of the hard X-ray spectra of bright Seyfert galaxies

    CERN Document Server

    Lubinski, P; Gibaud, L; Paltani, S; Papadakis, I E; Ricci, C; Soldi, S; Türler, M; Walter, R; Zdziarski, A A

    2016-01-01

    Hard X-ray spectra of 28 bright Seyfert galaxies observed with INTEGRAL were analyzed together with the X-ray spectra from XMM-Newton, Suzaku and RXTE. These broad-band data were fitted with a model assuming a thermal Comptonization as a primary continuum component. We tested several model options through a fitting of the Comptonized continuum accompanied by a complex absorption and a Compton reflection. Both the large data set used and the model space explored allowed us to accurately determine a mean temperature kTe of the electron plasma, the Compton parameter y and the Compton reflection strength R for the majority of objects in the sample. Our main finding is that a vast majority of the sample (20 objects) is characterized by kTe 200 keV. The median kTe for entire sample is 48(-14,+57) keV. The distribution of the y parameter is bimodal, with a broad component centered at ~0.8 and a narrow peak at ~1.1. A complex, dual absorber model improved the fit for all data sets, compared to a simple absorption mo...

  20. Resonant soft X-ray fluorescence spectra of molecules

    Energy Technology Data Exchange (ETDEWEB)

    Nordgren, J.; Glans, P.; Gunnelin, K.; Guo, J.; Skytt, P.; Saathe, C.; Wassdahl, N. [Uppsala Univ. (Sweden). Dept. of Phys.

    1997-08-01

    A review is presented of some recent advancements in resonant soft X-ray fluorescence spectroscopy applied to molecules. The concept of inelastic scattering is discussed for molecules with an element of symmetry, which introduces degeneracy or near-degeneracy of core excited states. The potential of the symmetry selection rules associated with resonant X-ray fluorescence is illustrated in studies of electronic structure as well as molecular dynamics. The use of polarized photons for exciting X-ray emission is discussed, and examples are presented where anisotropy of X-ray emission provides more detailed information. A brief section discusses the experimental considerations relevant for the spectroscopic technique. (orig.) With 013 figs., 28 refs.

  1. X-ray measurements on wood - spectra measurements

    DEFF Research Database (Denmark)

    Jensen, Signe Kamp; Thygesen, Lisbeth Garbrecht; Gerward, Leif

    The report concerns simultaneous non-destructive measurements of water content and density of wood. Theoretically, this should be possible using a x-ray equipment newly build at BKM, and this work is an attempt to use the equipment for assessing water content and density of wood samples under...... laboratory conditions. A number of wood samples with different densities are placed at different relative humidities from 0.5 to 97 %RH. When equilibrium is obtained the samples are measured with the x-ray equipment such that 10 points are measured in the sample followed by measurements outside the sample...... (free-scanning). In this way 100 points are measured for each wood sample. This produces information about moisture content and density of the samples as water and wood attenuations of the x-rays are different for the different energy levels contained in the x-rays. The "real" density and moisture...

  2. X-Ray Spectra of The High-Mass X-RAY Binary 4U~1700-37 using BeppoSAX, Suzaku and RXTE Observations

    CERN Document Server

    Seifina, Elena; Shaposhnikov, Nikolai

    2016-01-01

    We present an X-ray spectral analysis of the high-mass binary 4U~1700-37 during its hard-soft state evolution. We use the BeppoSAX, Suzaku and RXTE (Rossi X-ray Timing Explorer), Suzaku and BeppoSAX observations for this investigation. We argue that the X-ray broad-band spectra during all spectral states can be adequately reproduced by a model, consisting of a low-temperature Blackbody component, two Comptonized components both due to the presence of a Compton cloud (CC) that up-scatters seed photons of $T_{s1}$~< 1.4 keV, and $T_{s2}<$1 keV, and an iron-line component. We find using this model that the photon power-law index is almost constant, $\\Gamma_{1}\\sim 2$ for all spectral states. However, $\\Gamma_{2}$ shows a behavior depending on the spectral state. Namely, $\\Gamma_{2}$ is quasi-constant at the level of $\\Gamma_{2}\\sim 2$ while the CC plasma temperature $kT^{(2)}_e$ is less than 40 keV; on the other hand, $\\Gamma_{2}$ is in the range of $1.3<\\Gamma_{2}<2$, when $kT^{(2)}_e$ is greater th...

  3. The X-ray Spectra of Black Hole X-ray Novae in Quiescence as Measured by Chandra

    CERN Document Server

    Kong, A K H; García, M R; Murray, S S; Barret, D

    2002-01-01

    We present Chandra observations of black hole X-ray novae V404 Cyg, A0620-00, GRO J1655-40 and XTE J1550-564 in quiescence. Their quiescent spectra can be well fitted by a power-law model with slope $\\alpha \\sim 2$. While a coronal (Raymond-Smith) model is also a statistically acceptable representation of the spectra, the best fit temperatures of these models is $\\sim 5$ times higher than that seen in active stellar coronae. These four spectra of quiescent X-ray novae are all consistent with that expected for accretion via an advection-dominated accretion flow (ADAF) and inconsistent with that expected from a stellar corona. This evidence for continued accretion in quiescence further strengthens the case for the existence of event horizons in black holes. Both A0620-00 and GRO J1655-40 were fainter than in previous observations, while V404 Cyg was more luminous and varied by a factor of 2 in a few ksec. A reanalysis of the X-ray data for XTE J1550-564 shows that (like V404 Cyg and A0620-00) its luminosity exc...

  4. Copper L X-ray spectra measured by a high resolution ion-induced X-ray spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Ryohei; Hamaguchi, Dai; Kageyama, Hiroyoshi [Kyoto Inst. of Tech. (Japan)] [and others

    1997-03-01

    High resolution L X-ray emission spectra of Cu have been measured by 0.75 MeV/u H, He, and F, 0.73 MeV/u Ar, 0.64 MeV/u Si, and 0.073 MeV/u Si ion impacts with a crystal spectrometer. The X-ray transition energies in the Cu target for L{iota}, L{eta}, L{alpha}{sub 1,2}, L{beta}{sub 1}, and L{beta}{sub 3,4} diagram lines induced by light ion impacts are determined, which are in good agreement with those given in the reference. The difference in L X-ray emission spectra produced by H, He, F, Si, and Ar ions are considered and the L{alpha}{sub 1,2} and L{beta}{sub 1} emission spectra are compared with the calculated ones based on the multiconfiguration Dirac-Fock method. (author)

  5. BROADBAND X-RAY PROPERTIES OF THE GAMMA-RAY BINARY 1FGL J1018.6–5856

    Energy Technology Data Exchange (ETDEWEB)

    An, Hongjun [Department of Physics/KIPAC, Stanford University, Stanford, CA 94305-4060 (United States); Bellm, Eric; Fuerst, Felix; Harrison, Fiona A. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Bhalerao, Varun [Inter University Center for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411007 (India); Boggs, Steven E.; Craig, William W.; Tomsick, John A. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Christensen, Finn E. [DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Hailey, Charles J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Kaspi, Victoria M. [Department of Physics, McGill University, Rutherford Physics Building, 3600 University Street, Montreal, QC H3A 2T8 (Canada); Natalucci, Lorenzo [Istituto Nazionale di Astrofisica, INAFIAPS, via del Fosso del Cavaliere, I-00133 Roma (Italy); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Zhang, William W. [Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2015-06-20

    We report on NuSTAR, XMM-Newton, and Swift observations of the gamma-ray binary 1FGL J1018.6–5856. We measure the orbital period to be 16.544 ± 0.008 days using Swift data spanning 1900 days. The orbital period is different from the 2011 gamma-ray measurement which was used in the previous X-ray study of An et al. using ∼400 days of Swift data, but is consistent with a new gamma-ray solution reported in 2014. The light curve folded on the new period is qualitatively similar to that reported previously, having a spike at phase 0 and broad sinusoidal modulation. The X-ray flux enhancement at phase 0 occurs more regularly in time than was previously suggested. A spiky structure at this phase seems to be a persistent feature, although there is some variability. Furthermore, we find that the source flux clearly correlates with the spectral hardness throughout all orbital phases, and that the broadband X-ray spectra measured with NuSTAR, XMM-Newton, and Swift are well fit with an unbroken power-law model. This spectrum suggests that the system may not be accretion-powered.

  6. Broadband X-ray Properties of the Gamma-ray Binary 1FGL J1018.6-5856

    CERN Document Server

    An, Hongjun; Bhalerao, Varun; Boggs, Steven E; Christensen, Finn E; Craig, William W; Fuerst, Felix; Hailey, Charles J; Harrison, Fiona A; Kaspi, Victoria M; Natalucci, Lorenzo; Stern, Daniel; Tomsick, John A; Zhang, William W

    2015-01-01

    We report on NuSTAR, XMM-Newton and Swift observations of the gamma-ray binary 1FGL J1018.6-5856. We measure the orbital period to be 16.544+/-0.008 days using Swift data spanning 1900 days. The orbital period is different from the 2011 gamma-ray measurement which was used in the previous X-ray study of An et al. (2013) using ~400 days of Swift data, but is consistent with a new gamma-ray solution reported in 2014. The light curve folded on the new period is qualitatively similar to that reported previously, having a spike at phase 0 and broad sinusoidal modulation. The X-ray flux enhancement at phase 0 occurs more regularly in time than was previously suggested. A spiky structure at this phase seems to be a persistent feature, although there is some variability. Furthermore, we find that the source flux clearly correlates with the spectral hardness throughout all orbital phases, and that the broadband X-ray spectra measured with NuSTAR, XMM-Newton, and Swift are well fit with an unbroken power-law model. Thi...

  7. X-ray spectra induced in highly charged 40Arq+ interacting with Au surface

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    By use of optical spectrum technology, the spectra of X-ray induced by highly charged 40Arq+ ions interacting with Au surface have been studied. The results show that the argon Kα X-ray were emitted from the hollow atoms formed below the surface. There is a process of multi-electron exciting in neutralization of the Ar16+ion, with electronic configuration 1s2 in its ground state below the solid surface. The yield of the projectile Kα X-ray is related to its initial electronic configuration, and the yield of the target X-ray is related to the projectile kinetic energy.

  8. Broadband observations of the X-ray burster 4U 1705-44 with BeppoSAX

    CERN Document Server

    Piraino, S; Mueck, B; Kaaret, P; Di Salvo, T; D'Ai, A; Iaria, R; Egron, E

    2016-01-01

    4U 1705-44 is one of the most-studied type I X-ray burster and Atoll sources. This source represents a perfect candidate to test different models proposed to self-consistently track the physical changes occurring between different spectral states because it shows clear spectral state transitions. The broadband coverage, the sensitivity and energy resolution of the BeppoSAX satellite offers the opportunity to disentangle the components that form the total X-ray spectrum and to study their changes according to the spectral state. Using two BeppoSAX observations carried out in August and October 2000, respectively, for a total effective exposure time of about 100 ks, we study the spectral evolution of the source from a soft to hard state. Energy spectra are selected according to the source position in the color-color diagram (CCD) Results. We succeeded in modeling the spectra of the source using a physical self-consistent scenario for both the island and banana branches (the double Comptonization scenario). The ...

  9. The x ray variability of NGC6814: Power spectra

    Science.gov (United States)

    Done, C.; Madejski, G. M.; Mushotsky, R. F.; Turner, T. J.; Koyama, K.; Kunieda, H.

    1992-01-01

    Simulation techniques are used to obtain the X-ray variability power spectrum of unevenly sampled GINGA data from NGC6814. A simple power law is not an adequate description of the power spectrum, with the residuals showing excess power on timescales consistent with the periodicity seen in EXOSAT observations of this object. However the shape of the folded lightcurve is very different, with 3 main peaks, two of which are separated by an extremely sharp dip instead of the single peak and small harmonic structure observed by EXOSAT. Using the dip as a fiducial mark, a second GINGA observation of this source taken one year later is found to be consistent with being completely periodic and phase coherent with this first GINGA observation. Thus the period is consistent with being constant over a period of 6 years, but phase coherence is only maintained on timescales of approximately 1 year. Over 75 percent of the total source variability is due to the periodic component (r.m.s. amplitude of 36 percent). The residual variability can be described as the more usual 'flicker noise' f(exp -1.1) powerlaw. This shows no apparent high frequency break on timescales greater than 300 seconds. Subtle differences in the shape of the folded light curve with energy, and the very large amount of power in the periodic component suggest occultation as its origin, though amplification of variability from an X-ray emitting 'hot spot' at the disk inner radius through gravitational lensing is also possible. The former suffers from the very arbitrary nature of the periodic timescale, while the latter is unattractive as it cannot simply explain the lack of high frequency break in the residual power. That these models probably fail to provide an adequate explanation may be due to the added complexity of anisotropy of the X-ray emission, suggested by the discrepancy between the lack of soft photons implied by the flat spectrum and the copious source of soft photons available from reprocessing in

  10. Toward broad-band x-ray detected ferromagnetic resonance in longitudinal geometry

    Energy Technology Data Exchange (ETDEWEB)

    Ollefs, K. [Fakultät für Physik, Universität Duisburg-Essen, Lotharstr. 1, 47057 Duisburg (Germany); European Synchrotron Radiation Facility (ESRF), CS 40220, 38043 Grenoble Cedex (France); Meckenstock, R.; Spoddig, D.; Römer, F. M.; Hassel, Ch.; Schöppner, Ch.; Farle, M. [Fakultät für Physik, Universität Duisburg-Essen, Lotharstr. 1, 47057 Duisburg (Germany); Ney, V.; Ney, A., E-mail: andreas.ney@jku.at [Fakultät für Physik, Universität Duisburg-Essen, Lotharstr. 1, 47057 Duisburg (Germany); Institut für Halbleiter-und Festkörperphysik, Johannes Kepler Universität, Altenberger Str. 69, 4040 Linz (Austria)

    2015-06-14

    An ultrahigh-vacuum-compatible setup for broad-band X-ray detected ferromagnetic resonance (XFMR) in longitudinal geometry is introduced which relies on a low-power, continuous-wave excitation of the ferromagnetic sample. A simultaneous detection of the conventional ferromagnetic resonance via measuring the reflected microwave power and the XFMR signal of the X-ray absorption is possible. First experiments on the Fe and Co L{sub 3}-edges of a permalloy film covered with Co nanostripes as well as the Fe and Ni K-edges of a permalloy film are presented and discussed. Two different XFMR signals are found, one of which is independent of the photon energy and therefore does not provide element-selective information. The other much weaker signal is element-selective, and the dynamic magnetic properties could be detected for Fe and Co separately. The dependence of the latter XFMR signal on the photon helicity of the synchrotron light is found to be distinct from the usual x-ray magnetic circular dichroism effect.

  11. X-ray spectra induced by slow highly charged Arq+ ions in collision with Nb surface

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The X-ray spectra of Nb surface induced by Arq+ (q =16,17) ions with the energy range from 10 to 20 keV/q were studied by the optical spectrum technology. The experimental results indicate that the multi-electron excitation occurred as a highly charged Ar16+ ion was neutralized below the metal surface. The K shell electron of Ar16+ was excited and then de-excited cascadly to emit K X-ray. The intensity of the X-ray emitted from K shell of the hollow Ar atom decreased with the increase of projectile kinetic energy. The intensity of the X-ray emitted from L shell of the target atom Nb increased with the increase of projectile kinetic energy. The X-ray yield of Ar17+ is three magnitude orders larger than that of Ar16+.

  12. X-ray spectra induced by slow highly charged Arq+ ions in collision with Nb surface

    Institute of Scientific and Technical Information of China (English)

    YANG ZhiHu; GAO ZhiMing; ZHANG XiaoAn; ZHU KeXin; YU DeYang; CAI XiaoHong; CUI Ying; CHEN XiMeng; SONG ZhangYong; SHAO JianXiong; RUAN FangFang; ZHANG HongQiang; DU Juan; LIU YuWen

    2008-01-01

    The X-ray spectra of Nb surface induced by Arq+ (q = 16,17) ions with the energy range from 10 to 20 keV/q were studied by the optical spectrum technology. The experimental results indicate that the multi-electron excitation occurred as a highly charged Ar16+ ion was neutralized below the metal surface. The K shell electron of Ar16+ was excited and then de-excited cascadly to emit K X-ray. The intensity of the X-ray emitted from K shell of the hollow Ar atom decreased with the increase of projectile kinetic energy. The intensity of the X-ray emitted from L shell of the target atom Nb increased with the increase of projectile kinetic energy. The X-ray yield of Ar17+ is three magnitude orders larger than that of Ar16+.

  13. First Principles Calculations for X-ray Resonant Spectra and Elastic Properties

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yongbin [Iowa State Univ., Ames, IA (United States)

    2004-01-01

    In this thesis, we discuss applications of first principles methods to x-ray resonant spectra and elastic properties calculation. We start with brief reviews about theoretical background of first principles methods, such as density functional theory, local density approximation (LDA), LDA+U, and the linear augmented plane wave (LAPW) method to solve Kohn-Sham equations. After that we discuss x-ray resonant scattering (XRMS), x-ray magnetic circular dichroism (XMCD) and the branching problem in the heavy rare earths Ledges. In the last chapter we discuss the elastic properties of the second hardest material AlMgB14.

  14. Comparison between X-ray photoelectron and X-ray absorption spectra of an environmental aerosol sample measured by synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kawai, J.; Yamamoto, T. [Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto (Japan); Tohno, S. [Department of Socio-Environmental Energy Science, Graduate School of Energy Science, Kyoto University, Uji, Kyoto (Japan); Kitajima, Y. [Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba (Japan)

    1999-01-04

    Sulfur X-ray photoelectron spectra (XPS) and X-ray absorption spectra (XAS) of an aerosol sample collected by an Andersen sampler were measured using a synchrotron beam line. While the XPS was more surface sensitive than XAS, the detection limit of XAS was better than that of XPS. It was concluded that the XAS was more suitable for the chemical state analysis of sulfur in aerosol samples than XPS. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  15. Improving Solar Soft X-Ray (SXR) Irradiance Results from Broadband Photometers with New SXR Spectral Measurements from a CubeSat

    Science.gov (United States)

    Woods, T. N.; Caspi, A.; Chamberlin, P. C.; Didkovsky, L. V.; Eparvier, F. G.; Jones, A. R.; Mason, J. P.; Moore, C. S.; Solomon, S. C.; Viereck, R. A.

    2016-12-01

    There are four decades of broadband soft X-ray (SXR) measurements, but these measurements cannot directly quantify the varying contributions of emission lines (bound-bound) amongst the thermal radiative recombination (free-bound) and thermal and non-thermal bremsstrahlung (free-free) continua. The Miniature X-ray Solar Spectrometer (MinXSS) CubeSat mission, that was deployed into orbit in May 2016, was designed to directly measure the SXR spectra to improve the understanding of flare energetics and for studying the SXR radiation impacts in Earth's ionosphere. The broadband SXR measurements include the two bands of 1.6-25 keV (0.05-0.8 nm) by the GOES X-Ray Sensor (XRS) since the 1970s and the even broader band of 0.2-12 keV (0.1-7 nm) from several missions, including the Yohkoh Soft X-ray Telescope (SXT, 1991-2001), Student Nitric Oxide Experiment (SNOE, 1998-2002), Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED, 2002-present), the Solar Radiation and Climate Experiment (SORCE, 2003-present), and the Solar Dynamics Observatory (SDO, 2010-present). These broadband SXR measurements have been helpful for resolving some differences between ionosphere models and measurements, but differences remain in understanding solar SXR spectral distribution and atmospheric photoelectron flux. The lack of spectral resolution in the SXR range is thought to be the culprit for most of these disagreements and is thus an underlying motivation for the MinXSS CubeSat mission. The new solar SXR spectra in the range of 0.5 to 30 keV (0.04 - 2.5 nm) from MinXSS, along with how they can improve the accuracy of the broadband SXR photometer measurements, will be presented.

  16. X-ray spectra for mamography; Espectros de rayos X para mamografia

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H.R.; Manzanares A, E.; Ramirez G, J.; Hernandez V, R.; Hernandez D, V.M.; Salas L, M.A. [UAZ, A.P. 336, 98000 Zacatecas (Mexico)]. e-mail: fermineutron@yahoo.com

    2008-07-01

    By means of Monte Carlo methods the X-ray spectra that produce Mammography equipment have been obtained. The mammographs are widely used with the purpose of diagnosing the cancer of the mammary glands. Different makers and mammographs models are distinguished by the voltage capacity and the current, exist as well as in the target type and filter. The targets that are used are Mo, Rh and W and the filters are Mo, Rh, Al and Be. In this work the results obtained by means of the MCNP code of the X-ray spectra take place when an electron beam of 28 keV is made impact on Mo, Rh and W targets, as well as the spectra that result of filtering these X rays using different types of filters. The resulting spectra contain the continuous spectrum of the stopping radiation, as well as the X rays characteristic of the used target. The utility of estimating the spectra of X rays by means of Monte Carlo is that it can use to estimate the absorbed dose by the gland, as well as the absorbed dose by other organs. It also allows to calculate the detector response. (Author)

  17. Invisible structures in the X-ray absorption spectra of actinides

    NARCIS (Netherlands)

    Kvashnina, Kristina O.; De Groot, Frank M F

    2014-01-01

    The X-ray absorption spectra of actinides are discussed with an emphasis on the fundamental effects that influence their spectral shape, including atomic multiplet theory, charge transfer theory and crystal field theory. Many actinide spectra consist of a single peak and it is shown that the use of

  18. Measuring x-ray spectra of flash radiographic sources [PowerPoint

    Energy Technology Data Exchange (ETDEWEB)

    Gehring, Amanda Elizabeth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Espy, Michelle A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Haines, Todd Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mendez, Jacob [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Moir, David C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sedillo, Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Shurter, Roger P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Volegov, Petr Lvovich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Webb, Timothy J [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-11-02

    The x-ray spectra of flash radiographic sources are difficult to measure. The sources measured were Radiographic Integrated Test Stand-6 (370 rad at 1 m; 50 ns pulse) and Dual Axis Radiographic Hydrodynamic Test Facility (DARHT) (550 rad at 1 m; 50 ns pulse). Features of the Compton spectrometer are described, and spectra are shown. Additional slides present data on instrumental calibration.

  19. A broadband X-ray study of the Geminga pulsar with NuSTAR And XMM-Newton

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Kaya; Gotthelf, Eric V.; Halpern, Jules P.; Beloborodov, Andrei M.; Hailey, Charles J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Dufour, Francois; Kaspi, Victoria M.; An, Hongjun [Department of Physics, McGill University, Montreal, QC H3A2T8 (Canada); Bachetti, Matteo [Université de Toulouse, UPS-OMP, IRAP, Toulouse (France); Boggs, Steven E.; Craig, William W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Christensen, Finn E. [DTU Space—National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Harrison, Fiona A. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Kouveliotou, Chryssa [NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States); Pivovaroff, Michael J. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Zhang, William W., E-mail: kaya@astro.columbia.edu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2014-10-01

    We report on the first hard X-ray detection of the Geminga pulsar above 10 keV using a 150 ks observation with the Nuclear Spectroscopic Telescope Array (NuSTAR) observatory. The double-peaked pulse profile of non-thermal emission seen in the soft X-ray band persists at higher energies. Broadband phase-integrated spectra over the 0.2-20 keV band with NuSTAR and archival XMM-Newton data do not fit to a conventional two-component model of a blackbody plus power law, but instead exhibit spectral hardening above ∼5 keV. We find that two spectral models fit the data well: (1) a blackbody (kT {sub 1} ∼ 42 eV) with a broken power law (Γ{sub 1} ∼ 2.0, Γ{sub 2} ∼ 1.4 and E {sub break} ∼ 3.4 keV) and (2) two blackbody components (kT {sub 1} ∼ 44 eV and kT {sub 2} ∼ 195 eV) with a power-law component (Γ ∼ 1.7). In both cases, the extrapolation of the Rayleigh-Jeans tail of the thermal component is consistent with the UV data, while the non-thermal component overpredicts the near-infrared data, requiring a spectral flattening at E ∼ 0.05-0.5 keV. While strong phase variation of the power-law index is present below ∼5 keV, our phase-resolved spectroscopy with NuSTAR indicates that another hard non-thermal component with Γ ∼ 1.3 emerges above ∼5 keV. The spectral hardening in non-thermal X-ray emission as well as spectral flattening between the optical and X-ray bands argue against the conjecture that a single power law may account for multi-wavelength non-thermal spectra of middle-aged pulsars.

  20. Radiative Spectra from Disk Corona and Inner Hot Flow in Black Hole X-ray Binaries

    CERN Document Server

    Kawabata, Ryoji

    2010-01-01

    To understand the origin of hard X-ray emissions from black hole X-ray binaries during their low/hard states, we calculate the X-ray spectra of black-hole accretion flow for the following three configurations of hot and cool media: (a) an inner hot flow and a cool outer disk (inner hot flow model), (b) a cool disk sandwiched by disk coronae (disk corona model), and (c) the combination of those two (hybrid model). The basic features we require for successful models are (i) significant hard X-ray emission whose luminosity exceeds that of soft X-rays, (ii) high hard X-ray luminosities in the range of (0.4 - 30) times 10^{37} erg s^{-1}, and (iii) the existence of two power-law components in the hard X-ray band with the photon indices of Gamma_s ~ 2 > Gamma_h, where Gamma_s and Gamma_h are the photon indices of the softer (10 keV) power-law components, respectively. Contribution by non-thermal electrons nor time-dependent evolution are not considered. We find that Models (a) and (b) can be ruled out, since the sp...

  1. Comparison of simulated and measured spectra of an industrial 450 kV X-ray tube

    Science.gov (United States)

    Miceli, A.; Thierry, R.; Bettuzzi, M.; Flisch, A.; Hofmann, J.; Sennhauser, U.; Casali, F.

    2007-09-01

    An accurate knowledge of the X-ray source spectrum is required in order to optimize X-ray Computed Tomography systems. A simulation model based on the Monte Carlo code GEANT4 was developed to determine the X-ray spectrum generated by a 450 kV tube. The X-ray spectra were measured using a Cadmium Telluride stack detector. The measured spectra were corrected for spurious detector effects and detector efficiency. The X-ray spectra simulated by GEANT4 were validated by comparison with X-ray spectra measured at 350, 400 and 450 kV. We observed a good agreement between the simulated and the measured X-ray spectra. In addition, we simulated and measured attenuation curves using aluminium and copper filtration. The comparison of the attenuation curves shows an excellent agreement.

  2. X-ray spectra induced by 129Xeq+ impacting the metal surface

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Using the slow highly charged ions 129 Xe q+ (q=25,26,27;initial kinetic T0≤4.65 keV/a.u.)to impact Au surface,the Au atomic Mαcharacteristic X-ray spectrum is induced.The result shows that as long as the charge state of projectile is high enough,the heavy atomic characteristic X-ray can be effectively excited even though the incident beam is very weak(nA magnitude),and the X-ray yield per ion is in the order of 10-8and increases with the kinetic energy and potential energy of projectile.By measuring the Au Mα-X-ray spectra,Au atomic N-level lifetime is estimated at about 1.33×10-18s based on Heisenberg uncertainty relation.

  3. Theoretical spectra of nonmagnetized low-mass X-ray binaries

    Science.gov (United States)

    Czerny, Bozena; Czerny, Michal; Grindlay, Jonathan E.

    1986-01-01

    Theoretical X-ray spectra of low-mass X-ray binaries with negligible magnetic fields are presented. The geometry of the X-ray emitting region, the energetic efficiency of the accretion in the disk and in the boundary layer which leads to a relation between the disk and the boundary layer luminosities, and the irradiation of the disk by the boundary layer are studied. The model of the radiation spectrum emerging from the neutron star and the innermost part of the disk is presented. The relativistic and Doppler effects and their influence on the spectrum as a function of inclination angle are discussed. A simple method for comparing the spectrum model with observations by studying the hardness ratio is given, and the results for three X-ray sources in globular clusters observed by the Einstein satellite are presented. The range of applicability of the spectrum models is also discussed.

  4. X-ray spectra induced by 129Xeq+ impacting the metal surface

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Using the slow highly charged ions 129Xeq+ (q = 25, 26, 27; initial kinetic T0≤4.65 keV/a.u.) to impact Au surface, the Au atomic Mα characteristic X-ray spectrum is induced. The result shows that as long as the charge state of projectile is high enough, the heavy atomic characteristic X-ray can be effectively excited even though the incident beam is very weak (nA magnitude), and the X-ray yield per ion is in the order of 10-8 and increases with the kinetic energy and potential energy of projectile. By measuring the Au Mα-X-ray spectra, Au atomic N-level lifetime is estimated at about 1.33×10-18 s based on Heisenberg uncertainty relation.

  5. Conception of broadband stigmatic high-resolution spectrometers for the soft X-ray range

    Energy Technology Data Exchange (ETDEWEB)

    Vishnyakov, E A; Shatokhin, A N; Ragozin, E N [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2015-04-30

    We formulate an approach to the development of stigmatic high-resolution spectral instruments for the soft X-ray range (λ ≤ 300 Å), which is based on the combined operation of normalincidence multilayer mirrors (including broadband aperiodic ones) and grazing-incidence reflection gratings with nonequidistant grooves (so-called VLS gratings). A concave multilayer mirror serves to produce a slightly astigmatic image of the radiation source (for instance, an entrance slit), and the diffraction grating produces a set of its dispersed stigmatic spectral images. The width of the operating spectral region is determined by the aperiodic structure of the multilayer mirror and may range up to an octave in wavelength. (laser applications and other topics in quantum electronics)

  6. X-ray reflected spectra from accretion disk models.II. Diagnostic tools for X-ray observations

    CERN Document Server

    Garcia, J; Mushotzky, R F

    2011-01-01

    We present a comprehensive study of the emission spectra from accreting sources. We use our new reflection code to compute the reflected spectra from an accretion disk illuminated by X-rays. This set of models covers different values of ionization parameter, solar iron abundance and photon index for the illuminating spectrum. These models also include the most complete and recent atomic data for the inner-shell of the iron and oxygen isonuclear sequences. We concentrate our analysis to the 2-10 keV energy region, and in particular to the iron K-shell emission lines. We show the dependency of the equivalent width (EW) of the Fe K$\\alpha$ with the ionization parameter. The maximum value of the EW is $\\sim 800$ eV for models with log $\\xi\\sim 1.5$, and decreases monotonically as $\\xi$ increases. For lower values of $\\xi$ the Fe K$\\alpha$ EW decreases to a minimum near log $\\xi\\sim 0.8$. We produce simulated CCD observations based on our reflection models. For low ionized, reflection dominated cases, the 2-10 keV...

  7. An indirect method of X-ray spectra measurement by simultaneous attenuations of the scattered beam

    Energy Technology Data Exchange (ETDEWEB)

    Mainardi, Raul T. [Facultad de Matematica, Astronomia y Fisica (FaMAF), Universidad Nacional de Cordoba, Ciudad Universitaria, X5000HUA-Cordoba (Argentina)], E-mail: mainardi@famaf.unc.edu.ar; Bonzi, Edgardo V. [Facultad de Matematica, Astronomia y Fisica (FaMAF), Universidad Nacional de Cordoba, Ciudad Universitaria, X5000HUA-Cordoba (Argentina)

    2008-05-15

    Direct and indirect methods of X-ray spectra determination present obstacles to their practical use since they must position either the collimator-detector assembly or the attenuators-ionization chamber, respectively, along the X-ray beam direction. These arrangements require considerable space and in many instances the detectors promptly saturate. An indirect procedure, which overcomes the aforementioned problems, is developed. It consists of the scattering of the X-ray beam from a carbon disk, which is detected simultaneously by several detectors placed away from the beam. The X-ray flux reaching each of these detectors is attenuated in metal sheets of different thicknesses, thus obtaining simultaneously the attenuation curve values. A set of analytical equations are derived to calculate attenuation curves by taking into account all the absorption and elastic and inelastic scattering processes that a beam of photons undergoes when going from the X-ray tube to the detector. Users, even those who are not well acquainted with computer programming, can easily obtain the X-ray spectrum by a least square fitting of a measured attenuation curve to a previously derived analytical expression. A simulated Monte Carlo program of photon transport from the X-ray tube to the detector provided simulated attenuation curves data. Analytically calculated and simulated attenuation curves for the same input spectrum wholly overlap and furthermore, reconstructed spectra from both sets of curves for different kilovoltages are also in full agreement. Finally, in addition to the importance of having the detectors out of the beam direction, the proposed arrangement features other main advantages, namely, only one X-ray tube shot is needed to obtain the required data, the physical processes involved are very well known, analytical equations are easily interpreted, and the measuring apparatuses can be comparatively simple to assemble and operate.

  8. On X-ray tube spectra, the dependence on the angular and electron energy of X-rays from the targets

    Science.gov (United States)

    Shaltout, A. A.

    2007-03-01

    An algorithm was developed for the theoretical intensities of both X-ray continuum and characteristic K-radiation (K{α 1}, K{α 2}, K{α }, K{β 1}, K{β 2}, K{β 3}, K{β 13}, K{β 4} and K{β 5}) of different target materials (Cr, Cu, Rh, Mo, W, Ag and Au) at different electron incidence angles (0.01circ 90circ), different take-off angles of the photon emission (0.01circ 90circ) and different X-ray tube voltages. It was found that the intensities of continuum and characteristic X-rays increase with increasing take-off angle and the take-off angle is inversely proportional to the absorption path of X-rays in the target. At take-off angles of 20circ or more, the flux of the X-ray spectra remains practically independent of the take-off angle. Furthermore, at the optimum electron incidence angle and take-off angle of emitted X-ray photons, the dependence of X-ray tube spectra on applied voltage was also investigated.

  9. Lifetime-vibrational interference effects in resonantly excited x-ray emission spectra of CO

    Energy Technology Data Exchange (ETDEWEB)

    Skytt, P.; Glans, P.; Gunnelin, K. [Uppsala Univ. (Sweden)] [and others

    1997-04-01

    The parity selection rule for resonant X-ray emission as demonstrated for O{sub 2} and N{sub 2} can be seen as an effect of interference between coherently excited degenerate localized core states. One system where the core state degeneracy is not exact but somewhat lifted was previously studied at ALS, namely the resonant X-ray emission of amino-substituted benzene (aniline). It was shown that the X-ray fluorescence spectrum resulting from excitation of the C1s at the site of the {open_quotes}aminocarbon{close_quotes} could be described in a picture separating the excitation and the emission processes, whereas the spectrum corresponding to the quasi-degenerate carbons could not. Thus, in this case it was necessary to take interference effects between the quasi-degenerate intermediate core excited states into account in order to obtain agreement between calculations and experiment. The different vibrational levels of core excited states in molecules have energy splittings which are of the same order of magnitude as the natural lifetime broadening of core excitations in the soft X-ray range. Therefore, lifetime-vibrational interference effects are likely to appear and influence the band shapes in resonant X-ray emission spectra. Lifetime-vibrational interference has been studied in non-resonant X-ray emission, and in Auger spectra. In this report the authors discuss results of selectively excited soft X-ray fluorescence spectra of molecules, where they focus on lifetime-interference effects appearing in the band shapes.

  10. Many-body effects on the x-ray spectra of metals

    Energy Technology Data Exchange (ETDEWEB)

    Satpathy, Sashi Sekhar [Univ. of Illinois, Urbana-Champaign, IL (United States)

    1982-01-01

    The effects of band structure, of a solid surface, of temperature, and of disorder on the many-electron x-ray spectra of metals are evaluated in a change-of-mean-field approximation using a one-dimensional nearest-neighbor tight-binding model of a metal. The x-ray spectral shapes are determined by both the band structure and the final-state interactions. The effect of the band being non-free-electron-like is not felt at the x-ray threshold, but away from it such effects are noticeable. When the core hole is created at the surface, the spectra at the edge exhibit a Nozieres-de Dominicis-type singularity with the appropriate surface phase-shifts. At energies away from the edge, the one-particle effects are prominent with the x-ray emission and absorption spectra closely reflecting the local one-electron density of states. The recoil spectrum of a Fermi sea at a non-zero temperature has less asymmetry than the zero-temperature case. It was found that at ordinary temperatures the reduction of the asymmetry due to the thermal distribution of one-electron states is not very significant. Finally, using a one-dimensional Anderson model, the effect of lattice disorder on the x-ray absorption spectra is studied for the first time. There are two effects: (1) the strong infrared divergence peak is gradually quenched as disorder is increased, and (2) the threshold is broadened because the threshold energies for absorption at different sites in the crystal depend on the varying local lattice environment. It is proposed that the x-ray spectra may be useful as a tool for studying the degree of electron localization in disordered many-electron systems.

  11. A search for effects on chemical isomerism in muonic X-ray spectra of propyl alcohol

    CERN Document Server

    Brandão d'Oliveira, A; Von Egidy, T

    1974-01-01

    The intensities of muonic X-ray transitions in n-propyl alcohol and isopropyl alcohol were measured. The experiment was performed at the muon channel of the 600 MeV synchrocyclotron at CERN. The spectra were evaluated by means of a standard computer program and by a technique to observe small differences between the propyl-alcohol spectra. No differences in the muonic spectra were observed within rather small experimental errors. (16 refs).

  12. OZSPEC-2: an improved broadband high-resolution elliptical crystal x-ray spectrometer for high-energy density physics experiments (invited).

    Science.gov (United States)

    Heeter, R F; Anderson, S G; Booth, R; Brown, G V; Emig, J; Fulkerson, S; McCarville, T; Norman, D; Schneider, M B; Young, B K F

    2008-10-01

    A novel time, space, and energy-resolved x-ray spectrometer has been developed which produces, in a single snapshot, a broadband and relatively calibrated spectrum of the x-ray emission from a high-energy density laboratory plasma. The opacity zipper spectrometer (OZSPEC-1) records a nearly continuous spectrum for x-ray energies from 240 to 5800 eV in a single shot. The second-generation OZSPEC-2, detailed in this work, records fully continuous spectra on a single shot from any two of these three bands: 270-650, 660-1580, and 1960-4720 eV. These instruments thus record thermal and line radiation from a wide range of plasmas. These instruments' single-shot bandwidth is unmatched in a time-gated spectrometer; conversely, other broadband instruments are either time-integrated (using crystals or gratings), lack spectral resolution (diode arrays), or cover a lower energy band (gratings). The OZSPECs are based on the zipper detector, a large-format (100x35 mm) gated microchannel plate detector, with spectra dispersed along the 100 mm dimension. OZSPEC-1 and -2 both use elliptically bent crystals of OHM, RAP, and/or PET. Individual spectra are gated in 100 ps. OZSPEC-2 provides one-dimensional spatial imaging with 30-50 microm resolution over a 1500 microm field of view at the source. The elliptical crystal design yields broad spectral coverage with resolution E/DeltaE>500, strong rejection of hard x-ray backgrounds, and negligible source broadening for extended sources. Near-term applications include plasma opacity measurements, detailed spectra of inertial fusion Hohlraums, and laboratory astrophysics experiments.

  13. Probing symmetry and symmetry breaking in resonant soft-x-ray fluorescence spectra of molecules

    Energy Technology Data Exchange (ETDEWEB)

    Glans, P.; Gunnelin, K.; Guo, J. [Uppsala Univ. (Sweden)] [and others

    1997-04-01

    Conventional non-resonant soft X-ray emission brings about information about electronic structure through its symmetry and polarization selectivity, the character of which is governed by simple dipole rules. For centro-symmetric molecules with the emitting atom at the inversion center these rules lead to selective emission through the required parity change. For the more common classes of molecules which have lower symmetry or for systems with degenerate core orbitals (delocalized over identical sites), it is merely the local symmetry selectivity that provides a probe of the local atomic orbital contribution to the molecular orbital. For instance, in X-ray spectra of first row species the intensities essentially map the p-density at each particular atomic site, and, in a molecular orbital picture, the contribution of the local p-type atomic orbitals in the LCAO description of the molecular orbitals. The situation is different for resonant X-ray fluorescence spectra. Here strict parity and symmetry selectivity gives rise to a strong frequency dependence for all molecules with an element of symmetry. In addition to symmetry selectivity the strong frequency dependence of resonant X-ray emission is caused by the interplay between the shape of a narrow X-ray excitation energy function and the lifetime and vibrational broadenings of the resonantly excited core states. This interplay leads to various observable effects, such as linear dispersion, resonance narrowing and emission line (Stokes) doubling. Also from the point of view of polarization selectivity, the resonantly excited X-ray spectra are much more informative than the corresponding non-resonant spectra. Examples are presented for nitrogen, oxygen, and carbon dioxide molecules.

  14. Broadband x-ray imaging and spectroscopy of the crab nebula and pulsar with NuSTAR

    DEFF Research Database (Denmark)

    Madsen, Kristin K.; Reynolds, Stephen; Harrison, Fiona

    2015-01-01

    We present broadband (3-78 keV) NuSTAR X-ray imaging and spectroscopy of the Crab nebula and pulsar. We show that while the phase-averaged and spatially integrated nebula + pulsar spectrum is a power law in this energy band, spatially resolved spectroscopy of the nebula finds a break at ~9 keV in...

  15. X-ray ionization yields and energy spectra in liquid argon

    CERN Document Server

    Bondar, A; Dolgov, A; Shekhtman, L; Sokolov, A

    2015-01-01

    The main purpose of this work is to provide reference data on X-ray ionization yields and energy spectra in liquid Ar to the studies in the field of Cryogenic Avalanche Detectors (CRADs) for rare-event experiments, based on noble-gas liquids. We present the results of two related researches. First, the X-ray recombination coefficients in the energy range of 10-1000 keV and ionization yields at different electric fields are determined in liquid Ar, based on the results of a dedicated experiment. Second, the energy spectra of pulsed X-rays in liquid Ar in the energy range of 15-40 keV, obtained in given experiments including that with the two-phase CRAD, are interpreted and compared to those calculated using a dedicated computer program, to correctly determine the incident X-ray energy. The X-ray recombination coefficients and ionization yields have for the first time been presented for liquid Ar in systematic way.

  16. X-ray ionization yields and energy spectra in liquid argon

    Energy Technology Data Exchange (ETDEWEB)

    Bondar, A.; Buzulutskov, A. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation); Dolgov, A. [Novosibirsk State University, 630090 Novosibirsk (Russian Federation); Shekhtman, L.; Sokolov, A. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation)

    2016-04-21

    The main purpose of this work is to provide reference data on X-ray ionization yields and energy spectra in liquid Ar to the studies in the field of Cryogenic Avalanche Detectors (CRADs) for rare-event and other experiments, based on liquid Ar detectors. We present the results of two related researches. First, the X-ray recombination coefficients in the energy range of 10–1000 keV and ionization yields at different electric fields, between 0.6 and 2.3 kV/cm, are determined in liquid Ar based on the results of a dedicated experiment. Second, the energy spectra of pulsed X-rays in liquid Ar in the energy range of 15−40 keV, obtained in given experiments including that with the two-phase CRAD, are interpreted and compared to those calculated using a computer program, to correctly determine the absorbed X-ray energy. The X-ray recombination coefficients and ionization yields have for the first time been presented for liquid Ar in systematic way.

  17. OTELO Survey: Deep BVRI broadband photometry of the Groth strip. II Properties of X-ray Emitters

    CERN Document Server

    Pović, M; García, A M Pérez; Bongiovanni, A; Cepa, J; Acosta-Pulido, J A; Alfaro, E; Castañeda, H; Lorenzo, M Fernández; Gallego, J; González-Serrano, J I; González, J J; Lara-López, M A

    2009-01-01

    The Groth field is one of the sky regions that will be targeted by the OTELO (OSIRIS Tunable Filter Emission Line Object) survey in the optical 820 nm and 920 nm atmospheric windows. This field has been observed by AEGIS (All-wavelength Extended Groth strip International Survey) covering the full spectral range, from X-rays to radio waves. Chandra X-ray data with total exposure time of 200ksec are analyzed and combined with optical broadband data of the Groth field in order to study a set of structural parameters of the X-ray emitters and its relation with X-ray properties. We processed the raw, public X-ray data using the Chandra Interactive Analysis of Observations and determined and analyzed different structural parameters in order to produce a morphological classification of X-ray sources. Finally, we analyzed the angular clustering of these sources using 2-point correlation functions. We present a catalog of 340 X-ray emitters with optical counterpart. We obtained the number counts and compared them with...

  18. Transmission properties of barite mortar using X-ray spectra measured with Cd Te detector

    Energy Technology Data Exchange (ETDEWEB)

    Santos, J. C.; Mariano, L.; Costa, P. R. [Universidade de Sao Paulo, Instituto de Fisica, Rua do Matao Travessa R. 187, Cidade Universitaria, 05508-090 Sao Paulo (Brazil); Tomal, A., E-mail: josilene@usp.br [Universidade Federal de Goias, Instituto de Fisica, Campus Samambaia, 74001-970 Goiania (Brazil)

    2014-08-15

    Current methods for calculating X-ray shielding barriers do not take into account spectral distribution of the beam transmitted by the protective material. This consideration is important in dose estimations for radiation workers and general public in diagnostic radiology facilities. The aim of the present study was to estimate barite mortar attenuation curves using X-ray spectra weighted by a workload distribution. These curves were described in units of ambient dose equivalent (H (10)), since it is the radiation quantity adopted by IAEA for dose assessment in medical environment. Attenuation curves were determined using the optimized model for shielding evaluation presented by Costa and Caldas (2002). Workload distribution presented by Simpkin (1996), measured primary spectra and mass attenuation coefficients of barite mortar were used as input data in this model. X-ray beams in diagnostic energy range were generated by an industrial X-ray tube with 3 mm of aluminum additional filtration. Primary experimental spectra were measured by a Cd Te detector and corrected by the response function of detector by means of a stripping procedure. Air kerma measurements were performed using an ionization chamber for normalization purpose of the spectra. The corrected spectra presented good agreement with spectra generated by a semi-empirical model. The variation of the ambient dose equivalent as a function of barite mortar thickness was calculated. Using these data, it was estimated the optimized thickness of protective barrier needed for shielding a particular area in an X-ray imaging facility. The results obtained for primary protective barriers exhibit qualitative agreement with those presented in literature. (Author)

  19. X-ray MCD spectra and distortions at Fe2+ L2,3 edges

    NARCIS (Netherlands)

    Wang, Xin; Groot, F.M.F. de; Cramer, S.P.

    1996-01-01

    We have shown from ligand field multiplet calculations that the shape of X-ray magnetic circular dichroism (XMCD) spectra changes drastically with the distortion parameter Ds. The temperature dependence study of XMCD makes it possible to determine both Ds and spin-orbit coupling.

  20. Normal incidence X-ray telescope power spectra of X-ray emission from solar active regions. I - Observations. II - Theory

    Science.gov (United States)

    Gomez, Daniel O.; Martens, Petrus C. H.; Golub, Leon

    1993-01-01

    Fourier analysis is applied to very high resolution image of coronal active regions obtained by the Normal Incidence X-Ray Telescope is used to find a broad isotropic power-law spectrum of the spatial distribution of soft X-ray intensities. Magnetic structures of all sizes are present down to the resolution limit of the instrument. Power spectra for the X-ray intensities of a sample of topologically different active regions are found which fall off with increasing wavenumber as 1/k-cubed. A model is presented that relates the basic features of coronal magnetic fluctuations to the subphotospheric hydrodynamic turbulence that generates them. The model is used to find a theoretical power spectrum for the X-ray intensity which falls off with increasing wavenumber as 1/k-cubed. The implications of a turbulent regime in active regions are discussed.

  1. Spectra Transmitted by Mortar Barite in x-ray Qualities Applied in Diagnostic Radiology as Shielding

    Science.gov (United States)

    Almeida, A. T., Jr.; Araújo, F. G. S.; Nogueira, M. S.; Santos, M. A. P.

    2016-07-01

    Concrete which contains water, cement and aggregate, is widely used in building construction such as medical hospitals. The CdZnTe spectrometry system was used to acquire the transmitted spectra in the RQR qualities and the stripping procedure was performed by taking into account both the contributions of efficiency and x-ray escape fraction, experimentally determined. The samples were prepared in rectangular plate format with dimensions of (5 x 5) cm with thicknesses varying from 0.2cm to 2cm and exposed to x-ray beams generated. The HVL and the mean energy in this energy range was determined.

  2. The spectra of accretion discs in low-mass X-ray binaries

    CERN Document Server

    Ross, R R

    1995-01-01

    We present self-consistent models for the radiative transfer in Shakura-Sunyaev accretion discs in bright low-mass X-ray binaries (LMXB). Our calculations include the full effects of incoherent Compton scattering and the vertical temperature structure within the disc, as well as the effects of Doppler blurring and gravitational redshift. We find that the observed X-ray spectra are well fit by exponentially cutoff power-law models. The difference between the observed total spectrum and our calculated disc spectrum should reveal the spectrum of the disc/neutron star boundary layer and other emitting regions considered to be present in LMXB.

  3. Resonant Auger Destruction and Iron K-Alpha Spectra in Compact X-ray Sources

    OpenAIRE

    Liedahl, Duane A.

    2005-01-01

    We examine the effects of resonant Auger destruction in modifying the intensities and flux distributions of K-alpha spectra from iron L-shell ions. Applications include X-ray irradiated stellar winds in X-ray binaries and accretion disk atmospheres. Using detailed atomic models, we find that resonant Auger destruction is selective, in that only a subset of the emitted K-alpha lines is highly attenuated. We also show that that the local excitation conditions can have a dramatic effect on the K...

  4. Spectra transmitted by mortar barite in X-Ray qualities applied in diagnostic radiology as shielding

    Energy Technology Data Exchange (ETDEWEB)

    Almeida Junior, Airton T., E-mail: airton.almeida@fundacentro.gov.br [Fundacaoo Jorge Duprat Figueiredo de Seguranca e Medicina do Trabalho (FUNDACENTRO), Belo Horizonte, MG (Brazil); Araujo, F.G.S. [Universidade Federal de Ouro Preto (REDEMAT/UFOP), MG (Brazil); Nogueira, M.S., E-mail: mnogue@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Santos, M.A.P. [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

    2015-07-01

    Concrete which contains water, cement and aggregate, is widely used in building construction such as medical hospitals. The CdZnTe spectrometry system was used to acquire the transmitted spectra in the RQR qualities and the stripping procedure was performed by taking into account both the contributions of efficiency and x-ray escape fraction, experimentally determined. The samples were prepared in rectangular plate format with dimensions of (5 x 5) cm with thicknesses varying from 0.2cm to 2cm and exposed to x-ray beams generated. The HVL and the mean energy in this energy range was determined. (author)

  5. Characterization of neutron yield and x-ray spectra of a High Flux Neutron Generator (HFNG)

    Science.gov (United States)

    Nnamani, Nnaemeka; HFNG Collaboration

    2015-04-01

    The High Flux Neutron Generator (HFNG) is a DD plasma-based source, with a self-loading target intended for fundamental science and engineering applications, including 40 Ar/39 Ar geochronology, neutron cross section measurements, and radiation hardness testing of electronics. Our first estimate of the neutron yield, based on the population of the 4.486 hour 115 In isomer gave a neutron yield of the order 108 n/sec; optimization is ongoing to achieve the design target of 1011 n/sec. Preliminary x-ray spectra showed prominent energy peaks which are likely due to atomic line-emission from back-streaming electrons accelerated up to 100 keV impinging on various components of the HFNG chamber. Our x-ray and neutron diagnostics will aid us as we continue to evolve the design to suppress back-streaming electrons, necessary to achieve higher plasma beam currents, and thus higher neutron flux. This talk will focus on the characterization of the neutron yield and x-ray spectra during our tests. A collimation system is being installed near one of the chamber ports for improved observation of the x-ray spectra. This work is supported by NSF Grant No. EAR-0960138, U.S. DOE LBNL Contract No. DE-AC02-05CH11231, U.S. DOE LLNL Contract No. DE-AC52-07NA27344, and the UC Office of the President Award 12-LR-238745.

  6. Photoionized Lines in the X-ray Spectra of SMC X-1

    CERN Document Server

    Vrtilek, S D; Boroson, B S; McCray, R

    2005-01-01

    We present a detailed spectral analysis of Chandra/ACIS-S CC mode observations of the massive X-ray binary system SMC X-1. The system was observed during both the high and low X-ray states of the roughly 60-day superorbital period. The continuum spectra during both states are well represented by a power law with photon index $\\alpha$=0.9 and a blackbody of kT = 0.15keV. The high state spectra are dominated by the continuum and independent of orbital phase whereas the low state spectra show a strong orbital dependence as well as line emission from O, Ne, Mg, Fe, and Si. This is consistent with the states attributed to disk precession: during the high state X-ray emission is dominated by the compact source which is abrubtly eclipsed and during the low state the compact object is hidden by the disk and a larger, less luminous scattering region is responsible for the X-ray emission. A prominent Ne IX feature places a stringent limit (Log $\\xi$ = 2.0-2.5) on the ionization parameter which constrains the wind dynam...

  7. Target optimization for desired X-ray spectra produced by laser plasma accelerated electrons

    Science.gov (United States)

    Lobok, Maxim; Brantov, Andrey; Bychenkov, Valery

    2016-10-01

    Different regimes of electron acceleration from low-density targets are investigated using three-dimensional numerical simulations. Multiple spatial target density profiles were examined, including laser pre-pulse modified targets. The size of the plasma corona is shown to be one of the main parameters characterizing the temperature and number of hot electrons, which determine the yield of X-ray radiation and its hardness. The generation of X-ray radiation by laser accelerated electrons, which impact the converter target located behind the laser target, was studied. The X-ray spectra were computed using Monte-Carlo simulations. This work was partially supported by the Russian Foundation for Basic Research 16-02-00088-a.

  8. PHASE-RESOLVED X-RAY SPECTRA OF MAGNETARS AND THE CORONAL OUTFLOW MODEL

    Energy Technology Data Exchange (ETDEWEB)

    Hascoët, Romain; Beloborodov, Andrei M. [Physics Department and Columbia Astrophysics Laboratory, Columbia University, 538 West 120th Street, New York, NY 10027 (United States); Den Hartog, Peter R., E-mail: hascoet@astro.columbia.edu [Stanford University HEPL/KIPAC, 452 Lomita Mall, Stanford, CA 94305-4085 (United States)

    2014-05-01

    We test a model recently proposed for the persistent hard X-ray emission from magnetars. In the model, hard X-rays are produced by a decelerating electron-positron flow in the closed magnetosphere. The flow decelerates as it radiates its energy away via resonant scattering of soft X-rays, then it reaches the top of the magnetic loop and annihilates there. We test the model against observations of three magnetars: 4U 0142+61, 1RXS J1708-4009, and 1E 1841-045. We find that the model successfully fits the observed phase-resolved spectra. We derive constraints on the angle between the rotational and magnetic axes of the neutron star, the object inclination to the line of sight, and the size of the active twisted region filled with the plasma flow. Using the fit of the hard X-ray component of the magnetar spectrum, we revisit the remaining soft X-ray component. We find that it can be explained by a modified two-temperature blackbody model. The hotter blackbody is consistent with a hot spot covering 1%-10% of the neutron star surface. Such a hot spot is expected at the base of the magnetospheric e {sup ±} outflow, as some particles created in the e {sup ±} discharge flow back and bombard the stellar surface.

  9. Phase-resolved X-ray spectra of magnetars and the coronal outflow model

    CERN Document Server

    Hascoet, R; Hartog, P R den

    2014-01-01

    We test a model recently proposed for the persistent hard X-ray emission from magnetars. In the model, hard X-rays are produced by a decelerating electron-positron flow in the closed magnetosphere. The flow decelerates as it radiates its energy away via resonant scattering of soft X-rays, then it reaches the top of the magnetic loop and annihilates there. We test the model against observations of three magnetars: 4U 0142+61, 1RXS J1708-4009, and 1E 1841-045. We find that the model successfully fits the observed phase-resolved spectra. We derive constraints on the angle between the rotational and magnetic axes of the neutron star, the object inclination to the line of sight, and the size of the active twisted region filled with the plasma flow. Using the fit of the hard X-ray component of the magnetar spectrum, we revisit the remaining soft X-ray component. We find that it can be explained by a modified two-temperature blackbody model. The hotter blackbody is consistent with a hot spot covering 1-10% of the ne...

  10. Modeling of the EUV and X-Ray Emission Spectra Induced by the Solar Winds Ions in the Heliosphere

    Science.gov (United States)

    Kharchenko, Vasili

    2005-01-01

    We have carried out investigation of the EUV and X-ray emission spectra induced in interaction between the Solar Wind (SW) and interstellar neutral gas. The spectra of most important SW ions have been computed for the charge-exchange mechanism of X-ray emission using new accurate spectroscopic data from recent laboratory measurements and theoretical calculations. Total spectra have been constructed as a sum of spectra induced in the charge-exchange collisions by individual O(exp q+), C(exp q+), N(exp q+), Ne(exp q+), Mg (exp q+) and Fe(exp q+) ions. Calculations have been performed for X-ray emission from the heliospheric hydrogen and helium gas. X-ray maps of the heliosphere have been computed. The power density of X-ray sources in the heliospheric ecliptic plane is shown for the H gas and for the He gas. Distances from the Sun (0,0) are given in AU. The helium cone is clear seen in the X-ray map of the charge-exchange emission induced by the solar wind. X-ray emission spectra detected by the Chandra X-ray telescope from the "dark" side of Moon has been identified as a X-ray background emission induced by the solar wind from the geocorona. Spectra and intensities of this charge-exchange X-rays have been compared with the heliospheric component of the X-ray background. Observations and modeling of the SW spectra induced from the geocorona indicate a strong presence of emission lines of highly charged oxygen ions. Anisotropy in distribution of heliospheric X-rays has been predicted and calculated for the regions of the fast and slow solar winds.

  11. Modelling the variable broad-band optical/UV/X-ray spectrum of PG1211+143: Implications for the ionized outflow

    CERN Document Server

    Papadakis, I E; Panagiotou, C

    2016-01-01

    We present the results from a detailed analysis of the 2007 Swift monitoring campaign of the quasar PG1211+143. We constructed broad-band, optical/UV/X-ray spectral energy distributions over three X-ray flux intervals. We fitted them with a model which accounts for the disc and the X-ray coronal emission and the warm absorber (well established in this source). The three flux spectra are well fitted by the model we considered. The disc inner temperature remains constant at ~2 eV, while X-rays are variable both in spectral slope and normalization. The absorber covers almost 90% of the central source. It is outflowing with a velocity less than 2.3*10^4 km/s (3sigma upper limit), and has a column density of ~10^23.2. Its ionization parameter varies by a factor of 1.6, and it is in photo-ionizing equilibrium with the ionizing flux. It is located at a distance of less than 0.35 pc from the central source and its relative thickness, DR/R is less than 0.1. The absorber' s ionization parameter variations can explain t...

  12. Evolution of Hard X-Ray Spectra Along the Branches in Cir X-1

    CERN Document Server

    Ding, G Q; Li, T P

    2003-01-01

    Using the data from the PCA and HEXTE on board the RXTE satellite, we investigate the evolution of the 3-200 keV spectra of the peculiar low mass X-ray binary (LMXB) Cir X-1 along the branches on its hardness-intensity diagram (HID) from the vertical horizontal branch (VHB), through the horizontal horizontal branch (HHB) and normal branch (NB), to the flaring branch (FB). We detect a power-law hard component in the spectra. It is found that the derived photon indices ($\\Gamma$) of the power-law hard component are correlated with the position on the HID. The power-law component dominates the X-ray emission of Cir X-1 in the energy band higher than $\\sim 20$ keV. The fluxes of the power-law component are compared with those of the bremsstrahlung component in the spectra. A possible origin of the power-law hard component is discussed.

  13. X-ray nova MAXI J1828-249. Evolution of the broadband spectrum during its 2013-2014 outburst

    CERN Document Server

    Grebenev, S A; Burenin, R A; Krivonos, R A; Mescheryakov, A V

    2016-01-01

    Based on data from the SWIFT, INTEGRAL, MAXI/ISS orbital observatories, and the ground-based RTT-150 telescope, we have investigated the broadband (from the optical to the hard X-ray bands) spectrum of the X-ray nova MAXI J1828-249 and its evolution during the outburst of the source in 2013-2014. The optical and infrared emissions from the nova are shown to be largely determined by the extension of the power-law component responsible for the hard X-ray emission. The contribution from the outer cold regions of the accretion disk, even if the X-ray heating of its surface is taken into account, turns out to be moderate during the source's "high" state (when a soft blackbody emission component is observed in the X-ray spectrum) and is virtually absent during its "low" ("hard") state. This result suggests that much of the optical and infrared emissions from such systems originates in the same region of main energy release where their hard X-ray emission is formed. This can be the Compton or synchro-Compton radiati...

  14. Dynamical and Radiative Properties of X-Ray Pulsar Accretion Columns: Phase-averaged Spectra

    Science.gov (United States)

    West, Brent F.; Wolfram, Kenneth D.; Becker, Peter A.

    2017-02-01

    The availability of the unprecedented spectral resolution provided by modern X-ray observatories is opening up new areas for study involving the coupled formation of the continuum emission and the cyclotron absorption features in accretion-powered X-ray pulsar spectra. Previous research focusing on the dynamics and the associated formation of the observed spectra has largely been confined to the single-fluid model, in which the super-Eddington luminosity inside the column decelerates the flow to rest at the stellar surface, while the dynamical effect of gas pressure is ignored. In a companion paper, we have presented a detailed analysis of the hydrodynamic and thermodynamic structure of the accretion column obtained using a new self-consistent model that includes the effects of both gas and radiation pressures. In this paper, we explore the formation of the associated X-ray spectra using a rigorous photon transport equation that is consistent with the hydrodynamic and thermodynamic structure of the column. We use the new model to obtain phase-averaged spectra and partially occulted spectra for Her X-1, Cen X-3, and LMC X-4. We also use the new model to constrain the emission geometry, and compare the resulting parameters with those obtained using previously published models. Our model sheds new light on the structure of the column, the relationship between the ionized gas and the photons, the competition between diffusive and advective transport, and the magnitude of the energy-averaged cyclotron scattering cross-section.

  15. Direct Measurement of Mammographic X-Ray Spectra with a Digital CdTe Detection System

    Directory of Open Access Journals (Sweden)

    Giuseppe Raso

    2012-06-01

    Full Text Available In this work we present a detection system, based on a CdTe detector and an innovative digital pulse processing (DPP system, for high-rate X-ray spectroscopy in mammography (1–30 keV. The DPP system performs a height and shape analysis of the detector pulses, sampled and digitized by a 14-bit, 100 MHz ADC. We show the results of the characterization of the detection system both at low and high photon counting rates by using monoenergetic X-ray sources and a nonclinical X-ray tube. The detection system exhibits excellent performance up to 830 kcps with an energy resolution of 4.5% FWHM at 22.1 keV. Direct measurements of clinical molybdenum X-ray spectra were carried out by using a pinhole collimator and a custom alignment device. A comparison with the attenuation curves and the half value layer values, obtained from the measured and simulated spectra, from an ionization chamber and from a solid state dosimeter, also shows the accuracy of the measurements. These results make the proposed detection system a very attractive tool for both laboratory research, calibration of dosimeters and advanced quality controls in mammography.

  16. X-ray emission of SNRs in nonuniform medium: properties of thermal and nonthermal spectra

    Science.gov (United States)

    Petruk, O.

    2006-05-01

    In this report we consider two effects in the thermal and nonthermal spectra of supernova remnants (SNRs) which could be caused by the nonuniform ISM: i) the mimicry of the thermal X-ray spectrum of SNRs under the nonthermal one and ii) artificial broadening of the high-energy end of the nonthermal X-ray spectrum of SNRs. 1.There is possibility that the nonthermal features in the X-ray spectrum of some supernova remnants may be in fact of the thermal origin. Observed spectrum from SNRs is a superposition of ``individual'' spectra from different small volumes along the line of sight. The plasma is under different conditions in different places in SNR. The thermal X-ray spectrum of emission from a volume with high enough gradients of density and temperature may mimic under nonthermal one. This effect is studied with special attention to the case of supernova remnant evolution in the nonuniform interstellar medium like near molecular cloud. The mimicry-effect may be responsible for the nonthermal properties of X-ray spectra in those SNRs where nonthermal flux in photons with energy nonuniform interstellar medium. Time dependence of the maximum energy of electrons accelerated by the shock is also not able to make the observed spectrum considerably broader. The only possibility to produce broadening in the spectrum is the variation of the maximum energy of electrons over the surface of SNR. In such a case, the obliquity dependence of injection efficiency and/or magnetic field strength make also effect on the shape of the spectrum but their role is of the second order.

  17. Effect of Viewing Angle on Super-Soft-Source X-Ray Spectra

    Science.gov (United States)

    Ness, Jan-Uwe

    2012-09-01

    The advent of the X-ray grating spectrometers has given new momentum to the studies of Super-Soft-Source (SSS) X-ray spectra in high resolution. Earlier CCD-type spectra only allow determinations of effective temperatures while in the grating spectra, lines and continuum can be resolved. I have studied the X-ray grating spectra of eight classical novae during their SSS phase, two of them candidates for recurrent novae, two established recurrent novae, and four permanent SSSs including the prototypes Cal 83 and Cal 87. I discovered two categories of SSSs: those dominated by emission lines (SSSe) and by absorption line (SSSa). All spectra contain photospheric continuum emission, indicated by the shape of a blackbody. For the majority of SSSe, the inclination angle is known, which are all greater than 75 degrees. I argue that the SSSe are high-inclination systems in which photospheric X-ray emission from the central source is partially blocked and scattered via Thompson scattering, which preserves the spectral shape of the continuum. Since the electrons in the scattering medium move at high velocities, photospheric absorption lines are smeared out and are therefore not seen. Additional emission lines are produced by resonant line scattering. The fact that only high inclination systems show these effects of scattering, the scattering material must be concentrated to the ecliptic plane. While in permanent SSSs, the accretion disk can explain this behavior, this result implies that in novae, the reformation of the accretion disk has already progressed to an advanced stage during their SSS phase. I argue that also the novae in low-inclination angle systems possess a reformed accretion disk. The viewing angle dependence requires non-symmetrical modeling approaches. Early disk reformation can also explain high-amplitude variations that have frequently been observed during the early SSS phase.

  18. Measurements of X-ray doses and spectra produced by picosecond laser-irradiated solid targets.

    Science.gov (United States)

    Yang, Bo; Qiu, Rui; Yu, Minghai; Jiao, Jinlong; Lu, Wei; Yan, Yonghong; Zhang, Bo; Zhang, Zhimeng; Zhou, Weimin; Li, Junli; Zhang, Hui

    2017-02-09

    Experiments have shown that high-intensity laser interaction with a solid target can generate significant X-ray doses. This study was conducted to determine the X-ray doses and spectra produced for picosecond laser-irradiated solid targets. The photon doses and X-ray spectra in the laser forward and side directions were measured using an XG III ps 300 TW laser system. For laser intensities of 7×10(18)-4×10(19)W/cm(2), the maximum photon dose was 16.8 mSv at 50cm with a laser energy of ~153J on a 1-mm Ta target. The photon dose in the forward direction increased more significantly with increasing laser intensity than that in the side direction. For photon energies >300keV, the X-ray spectrum can be fit with an effective temperature distribution of the exponential form, dN/dE = k× exp(-E/Tx). The X-ray temperature Tx increased with the laser intensity in the forward direction with values of 0.46-0.75MeV. Tx was less strongly correlated with the laser intensity in the side direction with values of 0.29-0.32MeV. The escaping electron spectrum was also measured. The measured electron temperature was correlated with the electron temperature predicted by the ponderomotive law. The observations in this experiment were also investigated numerically. A good agreement was observed between the experimental and simulation results.

  19. On the soft X-ray spectra of $\\gamma$-loud blazars

    CERN Document Server

    Comastri, A; Ghisellini, G; Molendi, S

    1996-01-01

    ROSAT observations of a large sample of bright gamma-ray (E > 100 MeV) blazars are presented. Results of a detailed spectral analysis in the soft energy distribution with particular emphasis on the relation between X-ray and gamma-ray properties. A significant anti-correlation between X-ray and gamma-ray spectral shapes of flat radio spectrum quasars (FSRQ) and BL Lacs has been discovered. A different shape in the overall energy distributions from radio to gamma-ray energies between FSRQ and BL Lacs is also implied by the correlation of their broad-band spectral indices $\\alpha_{ro}$ and $\\alpha_{x emission and the hard X-ray to gamma-ray emission originate from the same electron population, via, respectively, the synchrotron process and the inverse Compton mechanism. We suggest that a key parameter for understanding the overall energy distributions of both classes of objects is the energy at which the synchrotron emission peaks in a $\

  20. K X-ray satellite spectra of Ti, V, Cr and Mn induced by photons

    Indian Academy of Sciences (India)

    M V R Murti; S S Raju; B Seetharami Reddy; V Koteswara Rao; L S Mombaswala; T Seshi Reddy; S Lakshminarayana; K Premachand

    2008-04-01

    K X-ray emission spectra of Ti, V, Cr and Mn generated by photon excitation have been studied with a crystal spectrometer. The measured energy shifts of K satellite relative to the diagram line are compared with values obtained by electron excitation and with different theoretical estimates. The present experimental values of KL1/KL0 relative intensities are compared with values obtained by electron excitation.

  1. New Insights into the X-Ray Spectra of Heliumlike and Neonlike Ions

    Energy Technology Data Exchange (ETDEWEB)

    Beiersdorfer, P; Chen, H; Hey, D; May, M; Osterheld, A; Reed, K; Scofield, J; Thorn, D; Bitter, M; Boyce, K R; Brown, G V; Gendreau, K C; Kelley, R L; Porter, F S; Stahle, C K; Szymkowiak, A E; Olson, R E; Lepson, J K; Gu, M F; Behar, E; Kahn, S M

    2002-04-11

    Recent measurements of the K-shell and L-shell x-ray spectra of highly charged helium-like and neon-like ions are presented that were performed on the Livermore electron beam ion traps and the Princeton tokamaks. These measurements provide new insights into collisional and indirect line formation processes, identifications of forbidden lines, and a new plasma line diagnostic of magnetic field strength.

  2. Reflection spectra from an accretion disc illuminated by a neutron star X-ray burst

    CERN Document Server

    Ballantyne, D R

    2004-01-01

    Recent time-resolved X-ray spectra of a neutron star undergoing a superburst revealed an Fe K line and edge consistent with reprocessing from the surrounding accretion disc. Here, we present models of X-ray reflection from a constant density slab illuminated by a blackbody, the spectrum emitted by a neutron star burst. The calculations predict a prominent Fe K line and a rich soft X-ray line spectrum which is superimposed on a strong free-free continuum. The lines slowly vanish as the ionization parameter of the slab is increased, but the free-free continuum remains dominant at energiesless than 1 keV. The reflection spectrum has a quasi-blackbody shape only at energies greater than 3 keV. If the incident blackbody is added to the reflection spectrum, the Fe K equivalent width varies between 100 and 300 eV depending on the ionization parameter and the temperature, kT, of the blackbody. The equivalent width is correlated with kT, and therefore we predict a strong Fe K line when an X-ray burst is at its brighte...

  3. Theory of pump–probe ultrafast photoemission and X-ray absorption spectra

    Energy Technology Data Exchange (ETDEWEB)

    Fujikawa, Takashi, E-mail: tfujikawa@faculty.chiba-u.jp; Niki, Kaori

    2016-01-15

    Highlights: • Pump–probe ultrafast XAFS and XPS spectra are theoretically studied. • Keldysh Green's function theory is applied. • Important many-body effects are explicitly included. - Abstract: Keldysh Green's function approach is extensively used in order to derive practical formulas to analyze pump–probe ultrafast photoemission and X-ray absorption spectra. Here the pump pulse is strong enough whereas the probe X-ray pulse can be treated by use of a perturbation theory. We expand full Green's function in terms of renormalized Green's function without the interaction between electrons and probe pulse. The present theoretical formulas allow us to handle the intrinsic and extrinsic losses, and furthermore resonant effects in X-ray Absorption Fine Structures (XAFS). To understand the radiation field screening in XPS spectra, we have to use more sophisticated theoretical approach. In the ultrafast XPS and XAFS analyses the intrinsic and extrinsic loss effects can interfere as well. In the XAFS studies careful analyses are necessary to handle extrinsic losses in terms of damped photoelectron propagation. The nonequilibrium dynamics after the pump pulse irradiation is well described by use of the time-dependent Dyson orbitals. Well above the edge threshold, ultrafast photoelectron diffraction and extended X-ray absorption fine structure (EXAFS) provide us with transient structural change after the laser pump excitations. In addition to these slow processes, the rapid oscillation in time plays an important role related to pump electronic excitations. Near threshold detailed information could be obtained for the combined electronic and structural dynamics. In particular high-energy photoemission and EXAFS are not so influenced by the details of excited states by pump pulse. Random-Phase Approximation (RPA)-boson approach is introduced to derive some practical formulas for time-dependent intrinsic amplitudes.

  4. HEAO 1 A-2 low-energy detector X-ray spectra of the Cygnus Loop

    Science.gov (United States)

    Leahy, D. A.; Fink, R.; Nousek, J.

    1990-01-01

    The Cygnus Loop supernova remnant was observed by the A-2 low-energy detector (LED) proportional counters on the HEAO 1 satellite. Recent improvements to the non-X-ray background rejection and detector response simulation have allowed production of the most accurate spectra of the Cygnus Loop to date. Three separate regions of the Cygnus Loop were observed. Single-temperature, Raymond-Smith models are inadequate to describe the spectra, but two component model fits are good. Temperature, column density, and emission measure variations across the Cygnus Loop are found. These results are interpreted and compared with previous work.

  5. HIGHER ORDER SPECIATION EFFECTS ON PLUTONIUM L3 X-RAY ABSORPTION NEAR EDGE SPECTRA.

    Energy Technology Data Exchange (ETDEWEB)

    Conradson, Steven D.; Abney, Kent D.; Begg, Bruce D.; Brady, Erik D.; Clark, David L.; den Auwer, Christophe; Ding, Mei; Dorhout, Peter K.; Espinosa-Faller, Francisco J.; Gordon, Pamela L.; Hess, Nancy J.; Hess, Ryan F.; Keogh, D. Webster; Lander, Gerard H.; Lupinetti, Anthony J.; Neu, Mary P.; Palmer, Phillip D.; Paviet-Hartmann, Patricia; Reilly, Sean D.; Runde, Wolfgang H.; Tait, C. Drew; Veirs, D. Kirk

    2003-06-09

    Pu L{sub 3} X-ray Near Edge Absorption Spectra for Pu(0-VII) are reported for more than 50 chalcogenides, chlorides, hydrates, hydroxides, nitrates, carbonates, oxy-hydroxides, and other compounds both as solids and in solution, and substituted in zirconlite, perovksite, and borosilicate glass. This large data base extends the known correlations between the energy and shape of these spectra from the usual association of the XANES with valence and site symmetry to higher order chemical effects. Because of the large number of compounds of these different types a number of novel and unexpected behaviors are observed.

  6. Microcalorimeter/EBIT measurements of X-ray spectra of highly charged ions

    Energy Technology Data Exchange (ETDEWEB)

    Kink, I.; Porto, J.V.; Gillaspy, J.D. [National Inst. of Standards and Technology, Gaithersburg, MD (United States); Laming, J.M. [Naval Research Lab., Washington, DC (United States); Takacs, E. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Silver, E.; Schnopper, H.; Bandler, S.R.; Brickhouse, N.; Murray, S. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Barbera, M. [Osservatorio Astronomico G.S. Vaiana, Palermo (Italy); Madden, N.; Landis, D.; Beeman, J.; Haller, E.E. [Lawrence Berkeley National Lab., CA (United States)

    2001-07-01

    Spectra of highly charged Ar, Kr, Xe and Fe ions, produced in an electron beam ion trap (EBIT), have been recorded in a broad X-ray energy band (0.2 keV to 10 keV) with a microcalorimeter detector. The first analysis of the Kr spectra has been completed and most of the spectral lines have been identified as transitions of B- to Al-like Kr. Line intensity ratios of Fe XVII have been measured and compared with theoretical models. (orig.)

  7. Broad-band X-ray emission and the reality of the broad iron line from the neutron star-white dwarf X-ray binary 4U 1820-30

    Science.gov (United States)

    Mondal, Aditya S.; Dewangan, G. C.; Pahari, M.; Misra, R.; Kembhavi, A. K.; Raychaudhuri, B.

    2016-09-01

    Broad relativistic iron lines from neutron star X-ray binaries are important probes of the inner accretion disc. The X-ray reflection features can be weakened due to strong magnetic fields or very low iron abundances such as is possible in X-ray binaries with low mass, first generation stars as companions. Here, we investigate the reality of the broad iron line detected earlier from the neutron-star low-mass X-ray binary 4U 1820-30 with a degenerate helium dwarf companion. We perform a comprehensive, systematic broad-band spectral study of the atoll source using Suzaku and simultaneous NuSTAR and Swift observations. We have used different continuum models involving accretion disc emission, thermal blackbody and thermal Comptonization of either disc or blackbody photons. The Suzaku data show positive and negative residuals in the region of Fe K band. These features are well described by two absorption edges at 7.67 ± 0.14 keV and 6.93 ± 0.07 keV or partial covering photoionized absorption or by blurred reflection. Though, the simultaneous Swift and NuSTAR data do not clearly reveal the emission or absorption features, the data are consistent with the presence of either absorption or emission features. Thus, the absorption based models provide an alternative to the broad iron line or reflection model. The absorption features may arise in winds from the inner accretion disc. The broad-band spectra appear to disfavour continuum models in which the blackbody emission from the neutron-star surface provides the seed photons for thermal Comptonization. Our results suggest emission from a thin accretion disc (kTdisc ˜ 1 keV), Comptonization of disc photons in a boundary layer most likely covering a large fraction of the neutron-star surface and innermost parts of the accretion disc, and blackbody emission (kTbb ˜ 2 keV) from the polar regions.

  8. Calculations of magnetic x-ray dichroism in the 3d absorption spectra of rare-earth compounds

    NARCIS (Netherlands)

    GOEDKOOP, JB; THOLE, BT; VANDERLAAN, G; SAWATZKY, GA; DEGROOT, FMF; FUGGLE, JC; de Groot, Frank

    1988-01-01

    We present atomic calculations for the recently discovered magnetic x-ray dichroism (MXD) displayed by the 3d x-ray-absorption spectra of rare-earth compounds. The spectral shapes expected at T=0 K for linear polarization parallel and normal to the local magnetic field is given, together with the te

  9. Krypton K-shell X-ray spectra recorded by the HENEX spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Seely, J.F. [Naval Research Laboratory, Space Science Division, Washington DC 20375 (United States)]. E-mail: john.seely@nrl.navy.mil; Back, C.A. [Lawrence Livermore National Laboratory, Livermore CA 94550 (United States); Constantin, C. [Lawrence Livermore National Laboratory, Livermore CA 94550 (United States); Lee, R.W. [Lawrence Livermore National Laboratory, Livermore CA 94550 (United States); Chung, H.-K. [Lawrence Livermore National Laboratory, Livermore CA 94550 (United States); Hudson, L.T. [National Institute of Standards and Technology, Gaithersburg MD 20899 (United States); Szabo, C.I. [National Institute of Standards and Technology, Gaithersburg MD 20899 (United States); Henins, A. [National Institute of Standards and Technology, Gaithersburg MD 20899 (United States); Holland, G.E. [SFA Inc., 9315 Largo Drive West Suite 200, Largo MD 20774 (United States); Atkin, R. [Tiger Innovations, L.L.C., 3610 Vacation Lane, Arlington VA 22207 (United States); Marlin, L. [Naval Research Laboratory, Space Science Division, Washington DC 20375 (United States)

    2006-05-15

    High-resolution X-ray spectra were recorded by the High-Energy Electronic X-ray (HENEX) spectrometer from a variety of targets irradiated by the Omega laser at the Laboratory for Laser Energetics. The HENEX spectrometer utilizes four reflection crystals covering the 1-20keV energy range and one quartz(10-11) transmission crystal (Laue geometry) covering the 11-40keV range. The time-integrated spectral images were recorded on five CMOS X-ray detectors. In the spectra recorded from krypton-filled gasbag and hohlraum targets, the helium-like K-shell transitions n=1-2, 1-3, and 1-4 appeared in the 13-17keV energy range. A number of additional spectral features were observed at energies lower than the helium-like n=1-3 and n=1-4 transitions. Based on computational simulations of the spectra using the FLYCHK/FLYSPEC codes, which included opacity effects, these additional features are identified to be inner-shell transitions from the Li-like through N-like krypton charge states. The comparisons of the calculated and observed spectra indicate that these transitions are characteristic of the plasma conditions immediately after the laser pulse when the krypton density is 2x10{sup 18}cm{sup -3} and the electron temperature is in the range 2.8-3.2keV. These spectral features represent a new diagnostic for the charge state distribution, the density and electron temperature, and the plasma opacity. Laboratory experiments indicate that it is feasible to record K-shell spectra from gold and higher Z targets in the >60keV energy range using a Ge(220) transmission crystal.

  10. Solar quiescent Active Region temperature distribution inferred from the Miniature Solar X-ray Solar Spectrometer (MinXSS) CubeSat soft X-ray spectra, Hinode X-ray Telescope (XRT) soft X-ray filter images and EUV measurements.

    Science.gov (United States)

    Moore, C. S.; Woods, T. N.; Caspi, A.; Mason, J. P.

    2016-12-01

    Soft X-rays serve as an important diagnostic tool for hot (T > 106 K) solar coronal plasma elemental composition, elemental ionization states, density of emitting plasma and dynamical events triggered by magnetic field structures. Spectrally resolved, solar disc averaged, soft X-ray spectra from the Miniature X-ray Solar Spectrometer (MinXSS) CubeSat combined with spatially resolved soft X-ray filter images from the Hinode X-ray Telescope (XRT) and complimentary EUV data can yield unique inferences of the quiescent (non-flaring) active regions' emitting plasma temperature distribution and chemical composition. This talk will discuss how the MinXSS spectra and Hinode XRT images from the sparsely measured 0.7 - 10 keV ( 0.124 - 1.77 nm) region, can augment estimations of active region temperature distribution and elemental abundance variations that are currently being assessed primarily from typical EUV and hard X-ray observations.

  11. Determination of x-ray spectra including characteristic line intensities from attenuation data

    Energy Technology Data Exchange (ETDEWEB)

    Rubio, M.; Mainardi, R.T. (Universidad Nacional de Cordoba (Argentina). Facultad de Matematica, Astronomia y Fisica)

    1984-11-01

    The Laplace pair transform method for the determination of X-ray spectral shapes has been modified by adding characteristic lines, assuming that the energy of each line is known. Their intensities are parameters to be determined by this extended method. A numerical simulation procedure was used to obtain attenuation data and from this all relevant parameters were determined: four parameters were allocated to the continuum plus one for each line considered. Measured X-ray spectral distributions taken from the literature were used both to generate attenuation data and also to verify the spectrum reconstruction procedure. Percentage differences from both sets of data are less than 8% and they were used to check the goodness of fit of the reconstructed spectra.

  12. BROADBAND X-RAY SPECTRAL INVESTIGATIONS OF MAGNETARS, 4U 0142+61, 1E 1841–045, 1E 2259+586, AND 1E 1048.1–5937

    Energy Technology Data Exchange (ETDEWEB)

    Weng, Shan-Shan [Department of Physics and Institute of Theoretical Physics, Nanjing Normal University, Nanjing 210023 (China); Göğüş, Ersin, E-mail: wengss@ihep.ac.cn [Sabancı University, Faculty of Engineering and Natural Sciences, Orhanlı,  Tuzla 34956, Istanbul (Turkey)

    2015-12-10

    We have generated an extended version of a rather simplified but physically oriented three-dimensional magnetar emission model, STEMS3D, to allow spectral investigations up to 100 keV. We then applied our model to the broadband spectra of four magnetars: 4U 0142+61, 1E 1841–045, 1E 2259+586, and 1E 1048.1–5937, using data collected with Swift/XRT or XMM-Newton in soft X-rays, and the Nuclear Spectroscopic Telescope Array in the hard X-ray band. We found that the hard X-ray emission of 4U 0142+61 was spectrally hard compared to earlier detections, indicating that the source was likely in a transition to or from a harder state. We find that the surface properties of the four magnetars are consistent with what we have obtained using only the soft X-ray data with STEMS3D, implying that our physically motivated magnetar emission model is a robust tool. Based on our broadband spectral investigations, we conclude that resonant scattering of the surface photons in the magnetosphere alone cannot account for the hard X-ray emission in magnetars; therefore, an additional non-thermal process, or a population of relativistic electrons is required. We also discuss the implication of the non-detection of persistent hard X-ray emission in 1E 1048.1–5937.

  13. Effects of characteristic x rays on the noise power spectra and detective quantum efficiency of photoconductive x-ray detectors.

    Science.gov (United States)

    Zhao, W; Ji, W G; Rowlands, J A

    2001-10-01

    The effects of K fluorescence on the imaging performance of photoconductor-based x-ray imaging systems are investigated. A cascaded linear systems model was developed, where a parallel cascaded process was implemented to take into account the effect of K-fluorescence reabsorption on the modulation transfer function (MTF), noise power spectrum (NPS), and the spatial frequency dependent detective quantum efficiency [DQE(f)] of an imaging system. The investigation was focused on amorphous selenium (a-Se), which is the most highly developed photoconductor material for x-ray imaging. The results were compared to those obtained with Monte Carlo simulation using the same imaging condition and detector parameters, so that the validity of the cascaded linear system model could be confirmed. Our results revealed that K-fluorescence reabsorption in a-Se is responsible for a 18% drop in NPS at high spatial frequencies with an incident x-ray photon energy of E=20 keV (which is just above the K edge of 12.5 keV). When E increases to 60 keV, the effects of K-fluorescence reabsorption on NPS decrease to approximately 12% at high spatial frequencies. Because the high frequency drop is present in both MTF and NPS, the effect of K fluorescence on DQE(f) is minimal, especially for E that is much higher than the K edge. We also applied the cascaded linear system model to a newly developed compound photoconductor, lead iodide (PbI2), and found that at 60 keV there is a high frequency drop in NPS of 19%. The calculated NPS were compared to previously published measurements of PbI2 detectors.

  14. X-ray spectra of high temperature tungsten plasma calculated with collisional radiative model

    Institute of Scientific and Technical Information of China (English)

    Wang Jun; Zhang Hong; Cheng Xin-Lu

    2013-01-01

    Tungsten is regarded as an important candidate of plasma facing material in international thermonuclear experimental reactor (ITER),so the determination and modeling of spectra of tungsten plasma,especially the spectra at high temperature were intensely focused on recently.In this work,using the atomic structure code of Cowan,a collisional radiative model (CRM) based on the spin-orbit-split-arrays is developed.Based on this model,the charge state distribution of tungsten ions is determined and the soft X-ray spectra from high charged ions of tungsten at different temperatures are calculated.The results show that both the average ionization charge and line positions are well agreed with others calculations and measurements with discrepancies of less than 0.63% and 1.26%,respectively.The spectra at higher temperatures are also reported and the relationship between ion abundance and temperature is predicted in this work.

  15. Changes in X-ray photoelectron spectra of yttria-tetragonal zirconia polycrystal by ion sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Eiko; Yoshinari, Masao [Tokyo Dental College, Oral Health Science Center, Tokyo, Chiyoda-ku (Japan)

    2016-04-15

    This paper reports changes in X-ray photoelectron spectroscopy spectra of yttria-tetragonal zirconia polycrystal (Y-TZP) brought about by Ar ion sputtering. The changes in the core-level spectra of Y-TZP suggest that preferential sputtering of oxygen occurred. A new peak was observed near 0 eV binding energy accompanied with changes in the core-level spectra by the sputtering. After 18 h in a high vacuum following the sputtering, the spectra changed by the sputtering were returned to their original shapes. In contrast, the color of Y-TZP was changed from white to pale brown by X-ray irradiation and was changed from pale brown to dark gray by ion sputtering. However, when the new peak near 0 eV decreased after 18 h, no color change was observed. Therefore, it is thought that the new peak was mainly derived from electrons trapped in various kinds of oxygen vacancies created by the sputtering in other than color centers. (orig.)

  16. Design of Grazing-Incidence Broad-Band Multilayers for Hard X-Ray Reflectors

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhong; WANG Zhan-Shan; WANG Feng-Li; QIN Shu-Ji; CHEN Ling-Yan

    2004-01-01

    @@ A new method of designing x-ray supermirrors with broad angular or energy response for use as coatings in x-ray optics is presented. The design is based on an analytical method with oversimplified analytical and semi-empirical formulae, and an extensive numerical method is used in the optimization design. A better initial multilayer is obtained with the former method and optimized with the latter method. In the optimization, a good design is achieved with much less computing time. In addition, the saturation effect due to the interfacial roughness in multilayer also emerges in the design of x-ray supermirrors with definite performances. The reflectivity of C/W x-ray supermirrors as a function of photon energy at the fixed grazing incident angle 0.5° is presented.

  17. Multidimensional resonant nonlinear spectroscopy with coherent broadband x-ray pulses

    Science.gov (United States)

    Bennett, Kochise; Zhang, Yu; Kowalewski, Markus; Hua, Weijie; Mukamel, Shaul

    2016-12-01

    New x-ray free electron laser (XFEL) and high harmonic generation (HHG) light sources are capable of generating short and intense pulses that make x-ray nonlinear spectroscopy possible. Multidimensional spectroscopic techniques, which have long been used in the nuclear magnetic resonance, infrared, and optical regimes to probe the electronic structure and nuclear dynamics of molecules by sequences of short pulses with variable delays, can thus be extended to the attosecond x-ray regime. This opens up the possibility of probing core-electronic structure and couplings, the real-time tracking of impulsively created valence-electronic wavepackets and electronic coherences, and monitoring ultrafast processes such as nonadiabatic electron-nuclear dynamics near conical-intersection crossings. We survey various possible types of multidimensional x-ray spectroscopy techniques and demonstrate the novel information they can provide about molecules.

  18. On the origin of X-ray spectra in luminous blazars

    Energy Technology Data Exchange (ETDEWEB)

    Sikora, Marek; Janiak, Mateusz; Moderski, Rafał [Nicolaus Copernicus Astronomical Center, Bartycka 18, 00-716 Warsaw (Poland); Nalewajko, Krzysztof [JILA, University of Colorado and National Institute of Standards and Technology, UCB 440, Boulder, CO 80309 (United States); Madejski, Greg M., E-mail: sikora@camk.edu.pl, E-mail: mjaniak@camk.edu.pl [Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory, Stanford University, 2575 Sand Hill Road M/S 29, Menlo Park, CA 94025 (United States)

    2013-12-10

    Gamma-ray luminosities of some quasar-associated blazars imply jet powers reaching values comparable to the accretion power even if assuming very strong Doppler boosting and very high efficiency of gamma-ray production. With much lower radiative efficiencies of protons than of electrons, and the recent reports of very strong coupling of electrons with shock-heated protons indicated by particle-in-cell simulations, the leptonic models seem to be strongly favored over the hadronic ones. However, the electron-proton coupling combined with the external-radiation-Compton (ERC) models of gamma-ray production in leptonic models predict extremely hard X-ray spectra, with energy indices α {sub x} ∼ 0. This is inconsistent with the observed 2-10 keV slopes of blazars, which cluster around α {sub x} ∼ 0.6. This problem can be resolved by assuming that electrons can be efficiently cooled down radiatively to non-relativistic energies, or that blazar spectra are entirely dominated by the synchrotron self-Compton (SSC) component up to at least 10 keV. Here, we show that the required cooling can be sufficiently efficient only at distances r < 0.03 pc. SSC spectra, on the other hand, can be produced roughly co-spatially with the observed synchrotron and ERC components, which are most likely located roughly at a parsec scale. We show that the dominant SSC component can also be produced much further than the dominant synchrotron and ERC components, at distances of ≳ 10 pc. Hence, depending on the spatial distribution of the energy dissipation along the jet, one may expect to see γ-ray/optical events with either correlated or uncorrelated X-rays. In all cases the number of e{sup +}e{sup –} pairs per proton is predicted to be very low. The direct verification of the proposed SSC scenario, and particularly the question of the co-spatiality of the SSC component with other spectral components, requires sensitive observations in the hard X-ray band. This is now possible with the

  19. Application of direct peak analysis to energy dispersive x-ray fluorescence spectra

    Energy Technology Data Exchange (ETDEWEB)

    Nielson, K.K.

    1977-07-01

    A modified Covell method for direct peak analysis has been applied to energy dispersive x-ray fluorescence spectra. The method is background independent and is well-suited to computerized data reduction. It provides acceptable precision, minimizes errors from instrumental gain shift, and permits peak overlap correction. Peak overlap errors exhibit both positive and negative nodes as a function of peak separation distance, and are corrected using concentration ratios determined from thin, single-element standards. Peak precisions and overlaps are evaluated as a function of window width to aid in width selection. Least-square polynomial smoothing prior to peak analysis significantly improves peak area precisions without significantly affecting their accuracies.

  20. Analysis of KLL Auger spectra excited by X-rays from Ni and Cu metal surfaces

    Science.gov (United States)

    Egri, S.; Kövér, L.; Cserny, I.; Novák, M.; Drube, W.

    2016-02-01

    Ni and Cu KLL Auger spectra excited by X-rays from polycrystalline metal foils were measured with good energy resolution and intensity earlier. Auger spectra of 3d transition metals contain satellite peaks due to the atomic excitation processes. Because of the complexity of the measured spectral shape a complete explanation of the spectra was not given in the previous works. A new analysis of the measured spectra is presented here, with improved description of effects of inelastic electron scattering of the electrons in the solid sample and using complex peak shapes to model the satellite structure that follows each diagram line. The energy loss part of measured spectra due to the bulk plasmon excitations, surface plasmon excitations and intrinsic loss processes was removed using the Partial Intensity Analysis method based on energy loss distributions obtained from experimental reflection electron energy loss spectra of the same Cu and Ni metal foils. Relative Auger-transition energies derived from measured spectra of copper are in good agreement with previous experimental works and the results of cluster molecular orbital multielectron (DV-ME) calculations. The intensity ratio I(3P2/3P0) shows better agreement with the result of relativistic calculations than in previous works. In the case of nickel the relative Auger-transition energies are in good agreement with the previous results. According to the new evaluation four satellite peaks were identified on the low energy side of each diagram line in the Auger spectra of Ni.

  1. Identifying Broadband Rotational Spectra with Neural Networks

    Science.gov (United States)

    Zaleski, Daniel P.; Prozument, Kirill

    2017-06-01

    A typical broadband rotational spectrum may contain several thousand observable transitions, spanning many species. Identifying the individual spectra, particularly when the dynamic range reaches 1,000:1 or even 10,000:1, can be challenging. One approach is to apply automated fitting routines. In this approach, combinations of 3 transitions can be created to form a "triple", which allows fitting of the A, B, and C rotational constants in a Watson-type Hamiltonian. On a standard desktop computer, with a target molecule of interest, a typical AUTOFIT routine takes 2-12 hours depending on the spectral density. A new approach is to utilize machine learning to train a computer to recognize the patterns (frequency spacing and relative intensities) inherit in rotational spectra and to identify the individual spectra in a raw broadband rotational spectrum. Here, recurrent neural networks have been trained to identify different types of rotational spectra and classify them accordingly. Furthermore, early results in applying convolutional neural networks for spectral object recognition in broadband rotational spectra appear promising. Perez et al. "Broadband Fourier transform rotational spectroscopy for structure determination: The water heptamer." Chem. Phys. Lett., 2013, 571, 1-15. Seifert et al. "AUTOFIT, an Automated Fitting Tool for Broadband Rotational Spectra, and Applications to 1-Hexanal." J. Mol. Spectrosc., 2015, 312, 13-21. Bishop. "Neural networks for pattern recognition." Oxford university press, 1995.

  2. Improved DQE by means of X-ray spectra and scintillator optimization for FFDM

    Science.gov (United States)

    Job, Isaias D.; Taie-Nobraie, Nima; Colbeth, Richard E.; Mollov, Ivan; Gray, Keith D.; Webb, Chris; Pavkovich, John M.; Zoghi, Fred; Tognina, Carlo A.; Roos, Pieter G.

    2012-03-01

    The focus of this work was to improve the DQE performance of a full-field digital mammography (FFDM) system by means of selecting an optimal X-ray tube anode-filter combination in conjunction with an optimal scintillator configuration. The flat panel detector in this work is a Varian PaxScan 3024M. The detector technology is comprised of a 2816 row × 3584 column amorphous silicon (a-Si) photodiode array with a pixel pitch of 83μm. The scintillator is cesium iodide and is deposited directly onto the photodiode array and available with configurable optical and x-ray properties. Two X-ray beam spectra were generated with the anode/filter combinations, Molybdenum/Molybdenum (Mo/Mo) and Tungsten/Aluminum (W/Al), to evaluate the imaging performance of two types of scintillators, high resolution (HR) type and high light output (HL) type. The results for the HR scintillator with W/Al anode-filter (HRW/ Al) yielded a DQE(0) of 67%, while HR-Mo/Mo was lower with a DQE(0) of 50%. In addition, the DQE(0) of the HR-W/Al configuration was comparable to the DQE(0) of the HL-Mo/Mo configuration. The significance of this result is the HR type scintillator yields about twice the light output with the W/Al spectrum, at about half the dose, as compared to the Mo/Mo spectrum. The light output or sensitivity was measured in analog-to-digital convertor units (ADU) per dose. The sensitivities (ADU/uGy) were 8.6, 16.8 and 25.4 for HR-Mo/Mo, HR-W/Al, HL-Mo/Mo, respectively. The Nyquist frequency for the 83 μm pixel is 6 lp/mm. The MTF at 5 lp/mm for HR-Mo/Mo and HR-W/Al were equivalent at 37%, while the HL-Mo/Mo MTF was 24%. According to the DQE metric, the more favorable anodefilter combination was W/Al with the HR scintillator. Future testing will evaluate the HL-W/Al configuration, as well as other x-ray filters materials and other scintillator optimizations. While higher DQE values were achieved, the more general conclusion is that the imaging performance can be tuned as required by

  3. X-ray spectra from magnetar candidates - III. Fitting SGRs/AXPs soft X-ray emission with non-relativistic Monte Carlo models

    CERN Document Server

    Zane, S; Turolla, R; Nobili, L

    2009-01-01

    Within the magnetar scenario, the "twisted magnetosphere" model appears very promising in explaining the persistent X-ray emission from the Soft Gamma Repeaters and the Anomalous X-ray Pulsars (SGRs and AXPs). In the first two papers of the series, we have presented a 3D Monte Carlo code for solving radiation transport as soft, thermal photons emitted by the star surface are resonantly upscattered by the magnetospheric particles. A spectral model archive has been generated and implemented in XSPEC. Here we report on the systematic application of our spectral model to different XMM-Newton and Integral observations of SGRs and AXPs. We find that the synthetic spectra provide a very good fit to the data for the nearly all the source (and source states) we have analyzed.

  4. A wavelet analysis for the X-ray absorption spectra of molecules

    Energy Technology Data Exchange (ETDEWEB)

    Penfold, T. J. [Ecole polytechnique Federale de Lausanne, Laboratoire de spectroscopie ultrarapide, ISIC, FSB-BSP, CH-1015 Lausanne (Switzerland); Ecole polytechnique Federale de Lausanne, Laboratoire de chimie et biochimie computationnelles, ISIC, FSB-BCH, CH-1015 Lausanne (Switzerland); SwissFEL, Paul Scherrer Inst, CH-5232 Villigen (Switzerland); Tavernelli, I.; Rothlisberger, U. [Ecole polytechnique Federale de Lausanne, Laboratoire de chimie et biochimie computationnelles, ISIC, FSB-BCH, CH-1015 Lausanne (Switzerland); Milne, C. J.; Abela, R. [SwissFEL, Paul Scherrer Inst, CH-5232 Villigen (Switzerland); Reinhard, M.; Nahhas, A. El; Chergui, M. [Ecole polytechnique Federale de Lausanne, Laboratoire de spectroscopie ultrarapide, ISIC, FSB-BSP, CH-1015 Lausanne (Switzerland)

    2013-01-07

    We present a Wavelet transform analysis for the X-ray absorption spectra of molecules. In contrast to the traditionally used Fourier transform approach, this analysis yields a 2D correlation plot in both R- and k-space. As a consequence, it is possible to distinguish between different scattering pathways at the same distance from the absorbing atom and between the contributions of single and multiple scattering events, making an unambiguous assignment of the fine structure oscillations for complex systems possible. We apply this to two previously studied transition metal complexes, namely iron hexacyanide in both its ferric and ferrous form, and a rhenium diimine complex, [ReX(CO){sub 3}(bpy)], where X = Br, Cl, or ethyl pyridine (Etpy). Our results demonstrate the potential advantages of using this approach and they highlight the importance of multiple scattering, and specifically the focusing phenomenon to the extended X-ray absorption fine structure (EXAFS) spectra of these complexes. We also shed light on the low sensitivity of the EXAFS spectrum to the Re-X scattering pathway.

  5. Energy dispersive X-ray diffraction to identify explosive substances: Spectra analysis procedure optimization

    Energy Technology Data Exchange (ETDEWEB)

    Crespy, C., E-mail: charles.crespy@insa-lyon.f [CNDRI-Insa Lyon, Universite de Lyon, F-69621, Villeurbanne cedex (France); Duvauchelle, P., E-mail: philippe.duvauchelle@insa-lyon.f [CNDRI-Insa Lyon, Universite de Lyon, F-69621, Villeurbanne cedex (France); Kaftandjian, V.; Soulez, F. [CNDRI-Insa Lyon, Universite de Lyon, F-69621, Villeurbanne cedex (France); Ponard, P. [Thales Components and Subsystems, 2 rue Marcel Dassault 78491, Velizy cedex (France)

    2010-11-21

    To detect the presence of explosives in packages, automated systems are required. Energy dispersive X-ray diffraction (EDXRD) represents a powerful non-invasive tool providing information on the atomic structure of samples. In this paper, EDXRD is investigated as a suitable technique for explosive detection and identification. To this end, a database has been constructed, containing measured X-ray diffraction spectra of several explosives and common materials. In order to quantify spectral resolution influence, this procedure is repeated with two different detectors which have different spectral resolution. Using our database, some standard spectrum analysis procedures generally used for this application have been implemented. Regarding to the results, it is possible to conclude on the robustness and the limits of each analysis procedure. The aim of this work is to define a robust and efficient sequence of EDXRD spectra analysis to discriminate explosive substances. Since our explosive substances are crystalline, the first step consists in using characteristic of the spectrum to estimate a crystallinity criterion which allows to remove a large part of common materials. The second step is a more detailed analysis, it consists in using similarity criterion and major peaks location to differentiate explosive from crystalline common materials. The influence of the spectral resolution on the detection is also examined.

  6. X-Ray Spectra from MHD Simulations of Accreting Black Holes

    Science.gov (United States)

    Schnittman, Jeremy D.; Krolik, Julian H.; Noble, Scott C.

    2012-01-01

    We present the results of a new global radiation transport code coupled to a general relativistic magneto-hydrodynamic simulation of an accreting, nonrotating black hole. For the first time, we are able to explain from first principles in a self-consistent way the X-ray spectra observed from stellar-mass black holes, including a thermal peak, Compton reflection hump, power-law tail, and broad iron line. Varying only the mass accretion rate, we are able to reproduce the low/hard, steep power-law, and thermal-dominant states seen in most galactic black hole sources. The temperature in the corona is T(sub e) 10 keV in a boundary layer near the disk and rises smoothly to T(sub e) greater than or approximately 100 keV in low-density regions far above the disk. Even as the disk's reflection edge varies from the horizon out to approximately equal to 6M as the accretion rate decreases, we find that the shape of the Fe Ka line is remarkably constant. This is because photons emitted from the plunging region are strongly beamed into the horizon and never reach the observer. We have also carried out a basic timing analysis of the spectra and find that the fractional variability increases with photon energy and viewer inclination angle, consistent with the coronal hot spot model for X-ray fluctuations.

  7. X-ray bursting neutron star atmosphere models: spectra and color corrections

    CERN Document Server

    Suleimanov, V; Werner, K

    2010-01-01

    X-ray bursting neutron stars in low mass X-ray binaries constitute an appropriate source class to constrain masses and radii of neutron stars, but a sufficiently extended set of corresponding model atmospheres is necessary for these investigations. We computed such a set of model atmospheres and emergent spectra in a plane-parallel, hydrostatic, and LTE approximation with Compton scattering taken into account. The models were calculated for six different chemical compositions: pure hydrogen and pure helium atmospheres, and atmospheres with solar mix of hydrogen and helium, and various heavy element abundances Z = 1, 0.3, 0.1, and 0.01 Z_sun. For each chemical composition the models are computed for three values of surface gravity, log g =14.0, 14.3, and 14.6, and for 20 values of the luminosity in units of the Eddington luminosity, L/L_Edd, in the range 0.001--0.98. The emergent spectra of all models are redshifted and fitted by a diluted blackbody in the RXTE/PCA 3--20 keV energy band, and corresponding valu...

  8. Emission lines between 1 and 2 keV in Cometary X-ray Spectra

    CERN Document Server

    Ewing, Ian; Bodewits, Dennis; Dennerl, Konrad; Lisse, Carey M; Wolk, Scott J

    2012-01-01

    We present the detection of new cometary X-ray emission lines in the 1.0 to 2.0 keV range using a sample of comets observed with the Chandra X-ray observatory and ACIS spectrometer. We have selected 5 comets from the Chandra sample with good signal-to-noise spectra. The surveyed comets are: C/1999 S4 (LINEAR), C/1999 T1 (McNaught-Hartley), 153P/2002 (Ikeya-Zhang), 2P/2003 (Encke), and C/2008 8P (Tuttle). We modeled the spectra with an extended version of our solar wind charge exchange (SWCX) emission model (Bodewits et al. 2007). Above 1 keV, we find Ikeya-Zhang to have strong emission lines at 1340 and 1850 eV that we identify as being created by solar wind charge exchange lines of Mg XI and Si XIII, respectively, and weaker emission lines at 1470, 1600, and 1950 eV formed by SWCX of Mg XII, Mg XI, and Si XIV, respectively. The Mg XI and XII and Si XIII and XIV lines are detected at a significant level for the other comets in our sample (LS4, MH, Encke, 8P), and these lines promise additional diagnostics to ...

  9. Imaging Grating SpectroPhotometer (I-GRASP) for Solar Soft X-Ray Spectra and Images from a Cube Sat Mission

    Science.gov (United States)

    Didkovsky, Leonid V.; Wieman, Seth; Woods, Thomas N.; Jones, Andrew; Chao, Weilun

    2016-05-01

    We describe the Soft X-ray Imaging Grating SpectroPhotometer (I-GRASP), a novel spectrophotometer with four times narrower transmission grating period (about 50 nm) compared to the MIT-designed 200 nm gratings successfully used for the SOHO/SEM, the SDO/EVE/ESP, and the Solar Aspect Monitor (SAM) onboard the EVE sounding rocket suite of instruments. The new grating is based on technology developed at the Lawrence Berkeley National Laboratory (LBNL) and provides four to five time greater diffraction dispersion than the 200 nm period gratings. Such new technology will provide detection of both 0.1 nm - resolved solar spectra in about 1.0 to 7.0 nm spectral range and a soft X-ray pin-hole solar image from the I-GRASP instrument that is appropriately sized for a CubeSat platform. The solar observations of this soft X-ray range do not currently have spectral resolution, so I-GRASP concurrent spectral and imaging X-ray observations will be important for:Improvements in modeling of coronal dynamics and heating by comparing measured and modeled spectra through identifying changes in abundances from different active regions- Resolving some differences in certain iron spectral line intensity ratios observed with SAM, identifying key emission lines, and comparing to those modeled with the CHIANTI atomic database- Studying SXR spectral variability for different solar activity periods including solar flares and the 27-day solar rotation- Studying of the Earth’s ionosphere, thermosphere and mesosphere responses using as input the detailed soft X-ray spectra from I-GRASP- Improving solar soft X-ray reference spectra for accurate calculations of absolute solar irradiance from the SDO/EVE/ESP, SDO/EVE/SAM, TIMED/SEE/XPS, and SORCE/XPS channels that have broadband measurements of the 1-7 nm band- Providing validation for the soft X-Ray observations from the MinXSS CubeSat X123 spectrometer (0.04 to 2.5 nm) with the I-GRASP spectral observations from 1.0 to 7.0 nm- Comparing I

  10. X-ray photoemission spectra for Al(x)Ga(1-x)As

    Science.gov (United States)

    Ireland, P. J.; Kazmerski, L. L.; Fisher, R. F.

    1984-06-01

    X-ray photoelectron spectroscopy (XPS) is used in both a qualitative and quantitative fashion to study the Al(x)Ga(1-x)As alloy. Gallium and aluminum atoms are always bonded to the arsenic atom. As the concentration of Al increases, a notable shift in the As-3d level could be expected as Ga and Al both have different electronegativities. Spectra taken on molecular beam epitaxially grown samples do not show this shift in the As-3d core level. The composition of the films have been measured with an electron probe, and these results agree very well with the XPS quantitative data. Standard spectra are presented for films with x = 0.16, 0.23, 0.32, 0.46, and 0.65.

  11. Relativistic Accretion Disk Models of High State Black Hole X-ray Binary Spectra

    CERN Document Server

    Davis, S W; Hubeny, I; Turner, N J; Davis, Shane W.; Blaes, Omer M.; Hubeny, Ivan; Turner, Neal J.

    2004-01-01

    We present calculations of non-LTE, relativistic accretion disk models applicable to the high/soft state of black hole X-ray binaries. We include the effects of thermal Comptonization and bound-free and free-free opacities of all abundant ion species. We present spectra calculated for a variety of accretion rates, black hole spin parameters, disk inclinations, and stress prescriptions. We also consider nonzero inner torques on the disk, and explore different vertical dissipation profiles, including some which are motivated by recent radiation MHD simulations of magnetorotational turbulence. Bound-free metal opacity generally produces significantly less spectral hardening than previous models which only considered Compton scattering and free-free opacity. It also tends to keep the effective photosphere near the surface, resulting in spectra which are remarkably independent of the stress prescription and vertical dissipation profile, provided little dissipation occurs above the effective photosphere. We provide...

  12. Unidentified line in x-ray spectra of the Andromeda galaxy and Perseus galaxy cluster.

    Science.gov (United States)

    Boyarsky, A; Ruchayskiy, O; Iakubovskyi, D; Franse, J

    2014-12-19

    We report a weak line at 3.52±0.02  keV in x-ray spectra of the Andromeda galaxy and the Perseus galaxy cluster observed by the metal-oxide-silicon (MOS) and p-n (PN) CCD cameras of the XMM-Newton telescope. This line is not known as an atomic line in the spectra of galaxies or clusters. It becomes stronger towards the centers of the objects; is stronger for Perseus than for M31; is absent in the spectrum of a deep "blank sky" data set. Although for each object it is hard to exclude that the feature is due to an instrumental effect or an atomic line, it is consistent with the behavior of a dark matter decay line. Future (non-)detections of this line in multiple objects may help to reveal its nature.

  13. The X-Ray Line Feature At 3.5 Kev In Galaxy Cluster Spectra

    CERN Document Server

    Phillips, K J H; Sylwester, J

    2015-01-01

    Recent work by Bulbul et al. and Boyarsky et al. has suggested that a line feature at approx. 3.5 keV in the X-ray spectra of galaxy clusters and individual galaxies seen with XMM-Newton is due to the decay of sterile neutrinos, a dark matter candidate. This identification has been criticized by Jeltema and Profumo on the grounds that model spectra suggest that atomic transitions in helium-like potassium (K XVIII) and chlorine (Cl XVI) are more likely to be the emitters. Here it is pointed out that the K XVIII lines have been observed in numerous solar flare spectra at high spectral resolution with the RESIK crystal spectrometer and also appear in Chandra HETG spectra of the coronally active star sigma Gem. In addition, the solar flare spectra at least indicate a mean coronal potassium abundance which is a factor of between 9 and 11 higher than the solar photospheric abundance. This fact, together with the low statistical quality of the XMM-Newton spectra, completely accounts for the approx. 3.5 keV feature a...

  14. Application of the Monte Carlo method to analyze materials used in flat panel detectors to obtain X-ray spectra

    Science.gov (United States)

    Gallardo, Sergio; Pozuelo, Fausto; Querol, Andrea; Ródenas, José; Verdú, Gumersindo

    2014-06-01

    An accurate knowledge of the photon spectra emitted by X-ray tubes in radiodiagnostic is essential to better estimate the imparted dose to patients and to improve the quality image obtained with these devices. In this work, it is proposed the use of a flat panel detector together with a PMMA wedge to estimate the actual X-ray spectrum using the Monte Carlo method and unfolding techniques. The MCNP5 code has been used to model different flat panels (based on indirect and direct methods to produce charge carriers from absorbed X-rays) and to obtain the dose curves and system response functions. Most of the actual flat panel devices use scintillator materials that present K-edge discontinuities in the mass energy-absorption coefficient, which strongly affect the response matrix. In this paper, the applicability of different flat panels for reconstructing X-ray spectra is studied. The effect of the mass energy-absorption coefficient of the scintillator material has been studied on the response matrix and consequently, in the reconstructed spectra. Different unfolding methods are tested to reconstruct the actual X-ray spectrum knowing the dose curve and the response function. It has been concluded that the regularization method MTSVD is appropriate to unfold X-ray spectra in all the scintillators studied.

  15. A Broadband X-Ray Study of the Supernova Remnant 3C 397

    CERN Document Server

    Safi-Harb, S; Arnaud, K A; Keohane, J W; Borkowski, K J; Dyer, K K; Reynolds, S P; Hughes, J P

    2000-01-01

    We present an X-ray study of the radio bright supernova remnant (SNR) 3C 397 with ROSAT, ASCA, and RXTE. A central X-ray spot seen with the ROSAT High-Resolution Imager hints at the presence of a pulsar-powered component, and gives this SNR a composite X-ray morphology. Combined ROSAT and ASCA imaging show that the remnant is highly asymmetric, with its hard X-ray emission peaking at the western lobe. The spectrum of 3C 397 is heavily absorbed, and dominated by thermal emission with emission lines evident from Mg, Si, S, Ar and Fe. Single-component models fail to describe the spectrum, and at least two components are required. We use a set of non-equilibrium ionization (NEI) models (Borkowski et al. in preparation). The temperatures from the soft and hard components are 0.2 keV and 1.6 keV respectively. The corresponding ionization time-scales $n_0 t$ ($n_0$ being the pre-shock hydrogen density) are 6 $\\times 10^{12}$ cm$^{-3}$ s and 6 $\\times$ 10$^{10}$ cm$^{-3}$ s, respectively. The spectrum obtained with t...

  16. Broad-band short term X-ray spectral variability of the quasar PDS 456

    Science.gov (United States)

    Matzeu, G.; Reeves, J.; Nardini, E.; Braito, V.; Costa, M.; Tombesi, F.

    2015-07-01

    We present an analysis of a recent 500 ks Suzaku observation, carried out in 2013, of the nearby (z=0.184) luminous (L_{bol}˜10^{47} erg s^{-1}) quasar PDS 456 in which the X-ray flux was unusually low. Short term X-ray spectral variability has been detected, which may be caused by two variable coverers of column density log (N_{H,1}/cm^{-2})=22.3±0.1 and log (N_{H,2}/cm(-2) )=23.2±0.1 We find that the partial covering requires an outflow velocity of ˜0.25 c, coincident with the velocity of the highly ionised outflow at the 99.9 % confidence level. Therefore the partial covering clouds could be the denser clumpy part of an inhomogeneous wind. An obscuration event occurs 1250 ks into the observation, where the spectrum becomes totally opaque at Fe K. This implies that the size of the absorber and likewise the X-ray emitter, to be less than 20 Rg. We also analyse the flaring behaviour in the lightcurve. The behaviour of the soft and hard X-ray flux, suggested a corona characterised by an extended "warm" region of ˜20 Rg in size combined with more compact regions of "hot" electrons of ˜8 Rg in size.

  17. A search for iron emission lines in the Chandra X-ray spectra of neutron star low-mass X-ray binaries

    CERN Document Server

    Cackett, E M; Homan, J; Van der Klis, M; Lewin, W H G; Méndez, M; Raymond, J; Steeghs, D; Wijnands, R

    2008-01-01

    While iron emission lines are well studied in black hole systems, both in X-ray binaries and Active Galactic Nuclei, there has been less of a focus on these lines in neutron star low-mass X-ray binaries (LMXBs). However, recent observations with Suzaku and XMM-Newton have revealed broad asymmetric iron line profiles in 4 neutron star LMXBs, confirming an inner disk origin for these lines in neutron star systems. Here, we present a search for iron lines in 6 neutron star LMXBs. For each object we have simultaneous Chandra and RXTE observations at 2 separate epochs, allowing for both a high resolution spectrum, as well as broadband spectral coverage. Out of the six objects in the survey, we only find significant iron lines in two of the objects, GX 17+2 and GX 349+2. However, we cannot rule out that there are weak, broad lines present in the other sources. The equivalent width of the line in GX 17+2 is consistent between the 2 epochs, while in GX 349+2 the line equivalent width increases by a factor of ~3 betwe...

  18. How realistic UV spectra and X-rays suppress the abundance of direct collapse black holes

    Science.gov (United States)

    Latif, M. A.; Bovino, S.; Grassi, T.; Schleicher, D. R. G.; Spaans, M.

    2015-01-01

    Observations of high-redshift quasars at z > 6 indicate that they harbour supermassive black holes (SMBHs) of a billion solar masses. The direct collapse scenario has emerged as the most plausible way to assemble SMBHs. The nurseries for the direct collapse black holes are massive primordial haloes illuminated with an intense UV flux emitted by Population II (Pop II) stars. In this study, we compute the critical value of such a flux (J_{21}^crit) for realistic spectra of Pop II stars through three-dimensional cosmological simulations. We derive the dependence of J_{21}^crit on the radiation spectra, on variations from halo to halo, and on the impact of X-ray ionization. Our findings show that the value of J_{21}^crit is a few times 104 and only weakly depends on the adopted radiation spectra in the range between Trad = 2 × 104and105 K. For three simulated haloes of a few times 107 M⊙, J_{21}^crit varies from 2 × 104 to 5 × 104. The impact of X-ray ionization is almost negligible and within the expected scatter of J_{21}^crit for background fluxes of JX, 21 ≤ 0.1. The computed estimates of J_{21}^crit have profound implications for the quasar abundance at z = 10 as it lowers the number density of black holes forming through an isothermal direct collapse by a few orders of magnitude below the observed black hole density. However, the sites with moderate amounts of H2 cooling may still form massive objects sufficient to be compatible with observations.

  19. X-ray Spectra and Pulse Frequency Changes in SAX J2103.5+4545

    CERN Document Server

    Baykal, A; Swank, J H

    2002-01-01

    The November 1999 outburst of the transient pulsar SAX J2103.5+4545 was monitored with the large area detectors of the Rossi X-Ray Timing Explorer until the pulsar faded after a year. The 358 s pulsar was spun up for 150 days, at which point the flux dropped quickly by a factor of 7, the frequency saturated and, as the flux continued to decline, a weak spin-down began. The pulses remained strong during the decay and the spin-up/flux correlation can be fit to the Ghosh and Lamb derivations for the spin-up caused by accretion from a thin, pressure-dominated disk, for a distance 3.2 kpc and a surface magnetic field 1.2 10^{13} Gauss. During the bright spin-up part of the outburst, the flux was subject to strong orbital modulation, peaking 3 days after periastron of the eccentric 12.68 day orbit, while during the faint part, there was little orbital modulation. The X-ray spectra were typical of accreting pulsars, describable by a cut-off power-law, with an emission line near the 6.4 keV of K alpha fluorescence fr...

  20. The influence of magnetic field geometry on magnetars X-ray spectra

    CERN Document Server

    Viganò, D; Zane, S; Turolla, R; Pons, J A; Miralles, J A

    2011-01-01

    Nowadays, the analysis of the X-ray spectra of magnetically powered neutron stars or magnetars is one of the most valuable tools to gain insight into the physical processes occurring in their interiors and magnetospheres. In particular, the magnetospheric plasma leaves a strong imprint on the observed X-ray spectrum by means of Compton up-scattering of the thermal radiation coming from the star surface. Motivated by the increased quality of the observational data, much theoretical work has been devoted to develop Monte Carlo (MC) codes that incorporate the effects of resonant Compton scattering in the modeling of radiative transfer of photons through the magnetosphere. The two key ingredients in this simulations are the kinetic plasma properties and the magnetic field (MF) configuration. The MF geometry is expected to be complex, but up to now only mathematically simple solutions (self-similar solutions) have been employed. In this work, we discuss the effects of new, more realistic, MF geometries on syntheti...

  1. On the origin of cyclotron lines in the spectra of X-ray pulsars

    Directory of Open Access Journals (Sweden)

    Mushtukov A. A.

    2014-01-01

    Full Text Available Cyclotron resonance scattering features are observed in the spectra of some X-ray pulsars and show significant changes in the line energy with the pulsar luminosity. In a case of bright sources, the line centroid energy is anti-correlated with the luminosity. Such a behaviour is often associated with the onset and growth of the accretion column, which is believed to be the origin of the observed emission and the cyclotron lines. However, this scenario inevitably implies large gradient of the magnetic field strength within the line-forming region, and it makes the formation of the observed line-like features problematic. Moreover, the observed variation of the cyclotron line energy is much smaller than could be anticipated for the corresponding luminosity changes. We argue that a more physically realistic situation is that the cyclotron line forms when the radiation emitted by the accretion column is reflected from the neutron star surface. The idea is based on the facts that a substantial part of column luminosity is intercepted by the neutron star surface and the reflected radiation should contain absorption features. The reflection model is developed and applied to explain the observed variations of the cyclotron line energy in a bright X-ray pulsar V 0332+53 over a wide range of luminosities.

  2. Uncertainty analysis in the simulation of X-ray spectra in the diagnostic range using the MCNP5 code.

    Science.gov (United States)

    Gallardo, S; Querol, A; Ródenas, J; Verdú, G

    2011-01-01

    An accurate knowledge of the photonic spectra emitted by X-ray tubes in radiodiagnostics is essential to better estimate the imparted dose to patients and to improve the image quality obtained with these devices. In this work, several X-ray spectra have been simulated using the MCNP5 code to simulate X-ray production in a commercial device. To validate the Monte Carlo results, simulated spectra have been compared to those extracted from the IPEM 78 database. The uncertainty associated to some geometrical features of the tube and its effect on the simulated spectra has been analyzed using the Noether-Wilks formula. This analysis has been focused on the thickness of collimators, filters, shielding and barrel shutter. Furthermore, results show that the uncertainty due to geometrical parameters (0.98% in terms of Root Mean Squared) is higher than the statistical uncertainty associated to the MCNP5 calculations.

  3. Effects of domain size on x-ray absorption spectra of boron nitride doped graphenes

    Science.gov (United States)

    Li, Xin; Hua, Weijie; Wang, Bo-Yao; Pong, Way-Faung; Glans, Per-Anders; Guo, Jinghua; Luo, Yi

    2016-08-01

    Doping is an efficient way to open the zero band gap of graphene. The control of the dopant domain size allows us to tailor the electronic structure and the properties of the graphene. We have studied the electronic structure of boron nitride doped graphenes with different domain sizes by simulating their near-edge X-ray absorption fine structure (NEXAFS) spectra at the N K-edge. Six different doping configurations (five quantum dot type and one phase-separated zigzag-edged type) were chosen, and N K-edge NEXAFS spectra were calculated with large truncated cluster models by using the density functional theory with hybrid functional and the equivalent core hole approximation. The opening of the band gap as a function of the domain size is revealed. We found that nitrogens in the dopant boundary contribute a weaker, red-shifted π* peak in the spectra as compared to those in the dopant domain center. The shift is related to the fact that these interfacial nitrogens dominate the lowest conduction band of the system. Upon increasing the domain size, the ratio of interfacial atom decreases, which leads to a blue shift of the π* peak in the total NEXAFS spectra. The spectral evolution agrees well with experiments measured at different BN-dopant concentrations and approaches to that of a pristine h-BN sheet.

  4. Bifurcation timescales in power spectra of black hole binaries and ultraluminous X-ray sources

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    For black hole binaries(BHBs) and active galactic nuclei(AGNs),bifurcation timescales(BTs) Δtb exist,below which time-domain power is significantly higher than the corresponding Fourier power.Quasi-periodic oscillations(QPOs) are removed from the Fourier spectra of BHBs.A relationship between BT,black hole mass and bolometric luminosity is derived.Strong anti-correlation between BT and luminosity of Cyg X-1 is found.After removing the QPOs,BTs are also obtained for two ultraluminous X-ray sources(ULXs),M82 X-1 and NGC5408 X-1.The results support that they harbor intermediate mass black holes(IMBHs).

  5. Multielectron excitations in x-ray absorption spectra of Rb and Kr

    Energy Technology Data Exchange (ETDEWEB)

    Kodre, A. [Faculty of Mathematics and Physics, University of Ljubljana (Slovenia); J. Stefan Institute, Ljubljana (Slovenia)]. E-mail: alojz.kodre@fmf.uni-lj.si; Arcon, I. [J. Stefan Institute, Ljubljana (Slovenia); Nova Gorica Polytechnics, Nova Gorica (Slovenia); Padeznik-Gomilsek J. [Faculty of Mechanical Engineering, University of Maribor, Maribor (Slovenia); Preseren, R. [Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana (Slovenia); Frahm, R. [Bergische Universitaet Gesamthochschule Wuppertal, Fachbereich 8-Physik, Wuppertal (Germany)

    2002-08-28

    In the K-edge x-ray absorption of rubidium vapour and gaseous krypton, comprehensive spectra of collective excitations down to the relative probability of 5x10{sup -5} are extracted. After removal of the asymptotic Victoreen trend, the region {approx}100 eV above the edge exhibits a steep decrease of the absorption coefficient attributed to core relaxation and post-collision interaction in the Auger decay. With an exponential model for the decrease, the entire spectrum of multielectron excitations is recognized as a succession of consecutive resonant, shake-up and shake-off channels. They can be identified as coexcitations of electrons from successively deeper subshells, from 5s down to 3s. The identification of excited states is aided by a quantitative modelling of subshell contributions and by natural-width deconvolution. The valence and subvalence coexcitations are shown to follow the pattern of the lighter homologues potassium and argon. (author)

  6. X-Ray CT of Highly-Attenuating Objects: 9- or 15- MV Spectra?

    Energy Technology Data Exchange (ETDEWEB)

    Stone, G; Trebes, J; Perry, R; Schneberk, D; Logan, C

    2005-08-29

    We imaged-highly attenuating test objects in three dimensions with 9-MV (at LLNL) and 15-MV (at Hill Air Force Base) x-ray spectra. While we used the same detector and motion control, there were differences that we could not control in the two radiography bays and in the sources. The results show better spatial resolution for the 9-MV spectrum and better contrast for the 15-MV spectrum. The 15-MV data contains a noise pattern that obfuscates the data. It is our judgment that if sufficient attention were given to design of the bay, beam dump, collimation, filtration and linac spot size; a 15-MV imaging system using a flat panel could be developed with spatial resolution of 5 lp/mm and contrastive performance better than we have demonstrated using a 9-MV spectrum.

  7. Shedding Light on the Compton-thick Active Galactic Nucleus in the Ultraluminous Infrared Galaxy UGC 5101 with Broadband X-Ray Spectroscopy

    Science.gov (United States)

    Oda, Saeko; Tanimoto, Atsushi; Ueda, Yoshihiro; Imanishi, Masatoshi; Terashima, Yuichi; Ricci, Claudio

    2017-02-01

    We report the broadband X-ray spectra of the ultraluminous infrared galaxy (ULIRG) UGC 5101 in the 0.25–100 keV band observed with the Swift/Burst Alert Telescope (BAT), Nuclear Spectroscopic Telescope Array (NuSTAR), Suzaku, XMM-Newton, and Chandra. A Compton-thick active galactic nucleus (AGN) obscured with a hydrogen column density of ≈ 1.3× {10}24 cm‑2 is detected above 10 keV. A spectral fit with a numerical torus model favors a large half-opening angle of the torus, > 41°, suggesting that the covering fraction of material heavily obscuring the X-ray source is moderate. The intrinsic 2–10 keV luminosity is determined to be ≈ 1.4× {10}43 erg s‑1, which is ≈ 2.5 times larger than the previous estimate using only data below 10 keV with a simple spectral model. We find that UGC 5101 shows the ratio between the [O iv] 26 μm line and 2–10 keV luminosities similar to those of normal Seyfert galaxies, along with other ULIRGs observed with NuSTAR, indicating that a significant portion of local ULIRGs are not really “X-ray faint” with respect to the flux of forbidden lines originating from the narrow-line region. We propose a possible scenario that (1) the AGN in UGC 5101 is surrounded not only by Compton-thick matter located close to the equatorial plane but also by Compton-thin ({N}{{H}}∼ {10}21 cm‑2) matter in the torus-hole region and (2) it is accreting at a high Eddington rate with a steep UV to X-ray spectral energy distribution. Nevertheless, we argue that AGNs in many ULIRGs do not look extraordinary (i.e., extremely X-ray faint), as suggested by recent works, compared with normal Seyferts.

  8. X-ray photoelectron spectra structure and chemical bonding in AmO2

    Directory of Open Access Journals (Sweden)

    Teterin Yury A.

    2015-01-01

    Full Text Available Quantitative analysis was done of the X-ray photoelectron spectra structure in the binding energy range of 0 eV to ~35 eV for americium dioxide (AmO2 valence electrons. The binding energies and structure of the core electronic shells (~35 eV-1250 eV, as well as the relativistic discrete variation calculation results for the Am63O216 and AmO8 (D4h cluster reflecting Am close environment in AmO2 were taken into account. The experimental data show that the many-body effects and the multiplet splitting contribute to the spectral structure much less than the effects of formation of the outer (0-~15 eV binding energy and the inner (~15 eV-~35 eV binding energy valence molecular orbitals. The filled Am 5f electronic states were shown to form in the AmO2 valence band. The Am 6p electrons participate in formation of both the inner and the outer valence molecular orbitals (bands. The filled Am 6p3/2 and the O 2s electronic shells were found to make the largest contributions to the formation of the inner valence molecular orbitals. Contributions of electrons from different molecular orbitals to the chemical bond in the AmO8 cluster were evaluated. Composition and sequence order of molecular orbitals in the binding energy range 0-~35 eV in AmO2 were established. The experimental and theoretical data allowed a quantitative scheme of molecular orbitals for AmO2, which is fundamental for both understanding the chemical bond nature in americium dioxide and the interpretation of other X-ray spectra of AmO2.

  9. Examining molecular clouds in the Galactic Centre region using X-ray reflection spectra simulations

    Science.gov (United States)

    Walls, M.; Chernyakova, M.; Terrier, R.; Goldwurm, A.

    2016-12-01

    In the centre of our Galaxy lies a supermassive black hole, identified with the radio source Sagittarius A⋆. This black hole has an estimated mass of around 4 million solar masses. Although Sagittarius A⋆ is quite dim in terms of total radiated energy, having a luminosity that is a factor of 1010 lower than its Eddington luminosity, there is now compelling evidence that this source was far brighter in the past. Evidence derived from the detection of reflected X-ray emission from the giant molecular clouds in the Galactic Centre region. However, the interpretation of the reflected emission spectra cannot be done correctly without detailed modelling of the reflection process. Attempts to do so can lead to an incorrect interpretation of the data. In this paper, we present the results of a Monte Carlo simulation code we developed in order to fully model the complex processes involved in the emerging reflection spectra. The simulated spectra can be compared to real data in order to derive model parameters and constrain the past activity of the black hole. In particular, we apply our code to observations of Sagittarius B2, in order to constrain the position and density of the cloud and the incident luminosity of the central source. The results of the code have been adapted to be used in XSPEC by a large community of astronomers.

  10. How realistic UV spectra and X-rays suppress the abundance of direct collapse black holes

    CERN Document Server

    Latif, M A; Grassi, T; Schleicher, D R G; Spaans, M

    2014-01-01

    Observations of high redshift quasars at $z>6$ indicate that they harbor supermassive black holes (SMBHs) of a billion solar masses. The direct collapse scenario has emerged as the most plausible way to assemble SMBHs. The nurseries for the direct collapse black holes are massive primordial halos illuminated with an intense UV flux emitted by population II stars. In this study, we compute the critical value of such a flux ($J_{21}^{\\rm crit}$) for realistic spectra of pop II stars through three-dimensional cosmological simulations. We derive the dependence of $J_{21}^{\\rm crit}$ on the radiation spectra, on variations from halo to halo, and on the impact of X-ray ionization. Our findings show that the value of $J_{21}^{\\rm crit}$ is a few times $\\rm 10^4$ and only weakly depends on the adopted radiation spectra in the range between $T_{\\rm rad}=2 \\times 10^4-10^5$ K. For three simulated halos of a few times $\\rm 10^{7}$~M$_{\\odot}$, $J_{21}^{\\rm crit}$ varies from $\\rm 2 \\times 10^4 - 5 \\times 10^4$. The impa...

  11. Examining molecular clouds in the Galactic Centre region using X-ray reflection spectra simulations

    CERN Document Server

    Walls, Michael; Terrier, Regis; Goldwurm, Andrea

    2016-01-01

    In the centre of our galaxy lies a super-massive black hole, identified with the radio source Sagittarius A*. This black hole has an estimated mass of around 4 million solar masses. Although Sagittarius A* is quite dim in terms of total radiated energy, having a luminosity that is a factor of $10^{10}$ lower than its Eddington luminosity, there is now compelling evidence that this source was far brighter in the past. Evidence derived from the detection of reflected X-ray emission from the giant molecular clouds in the galactic centre region. However, the interpretation of the reflected emission spectra cannot be done correctly without detailed modelling of the reflection process. Attempts to do so can lead to an incorrect interpretation of the data. In this paper we present the results of a Monte Carlo simulation code we developed in order to fully model the complex processes involved in the emerging reflection spectra. The simulated spectra can be compared to real data in order to derive model parameters and...

  12. Indirect measurements of X-ray spectra; Mediciones indirectas de espectros de rayos X

    Energy Technology Data Exchange (ETDEWEB)

    Mainardi, R.T. [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, X5000HUA Cordoba (Argentina)

    2006-07-01

    To the effects of measuring the spectral distribution of the radiation emitted by the x-ray tubes and electron accelerators, numerous procedures that are grouped in two big categories exist at the present time: direct and indirect methods. The first ones use high resolution detectors that should be positioned, together with the appropriate collimator, in the direction of the x ray beam. The user should be an expert in the use and correction of the obtained data by the different effects that affect the detector operation such as efficiency and resolution in terms of the energy of the detected radiation. The indirect procedures, although its are more simple to use, its also require a considerable space along the beam to position the ionization chamber and the necessary absorbents to construct by this way the denominated attenuation curve. We will analyze the operation principle of the indirect methods and a new proposal in which such important novelties are introduced as the beam dispersion to avoid to measure along the main beam and that of determination of the attenuation curve in simultaneous form. By this way, with a single shot of the tube, the attenuation curve is measured, being necessary at most a shot of additional calibration to know the relative response of the detectors used in the experimental array. The physical processes involved in the obtaining of an attenuation curve are very well well-known and this it finishes it can be theoretically calculated if the analytic form of the spectrum is supposed well-known. Finally, we will see a spectra reconstruction example with the Kramers parametric form and comparisons with numeric simulations carried out with broadly validated programs as well as the possibility of the use of solid state dosemeters in the obtention of the attenuation curve. (Author)

  13. X-ray diffraction, X-ray photoelectron spectra, crystal structure, and optical properties of centrosymmetric strontium borate Sr2B16O26.

    Science.gov (United States)

    Reshak, Ali Hussain; Auluck, S; Kityk, I V; Chen, Xuean

    2009-07-09

    We report results of X-ray diffraction (XRD) and valence band X- ray photoelectron (VB-XPS) spectra for strontium borate Sr(2)B(16)O(26). The X-ray structural analysis shows that the single crystals of Sr(2)B(16)O(26) crystallize in the monoclinic space group P2(1)/c with a = 8.408(1) A, b = 16.672(1) A, c = 13.901(2) A, beta = 106.33(1) degrees , and Z = 4. The crystal structure consists of a 3D network of the complex borate anion [B(16)O(20)O(12/2)](4-), formed by 12 BO(3) triangles and four BO(4) tetrahedra, which can be viewed as three linked [B(3)O(3)O(4/2)](-) triborate groups bonded to one pentaborate [B(5)O(6)O(4/2)](-) group and two BO(3) triangles. Using this structure, we have performed theoretical calculations using the all-electron full potential linearized augmented plane wave (FP-LAPW) method for the band structure, density of states, electron charge density, and the frequency-dependent optical properties. Our experimental VB-XPS of Sr(2)B(16)O(26) is compared with results of our FP-LAPW calculations. Our calculations show that the valence band maximum (VBM) and conduction band minimum (CBM) are located at Gamma of the Brillouin zone (BZ) resulting in a direct energy gap of about 5.31 eV. Our measured VB-XPS show reasonable agreement with our calculated total density of states for the valence band that is attributed to the use of the full potential method.

  14. X-Ray Absorption Spectra of Amorphous Ices from GW Quasiparticle Calculation

    Science.gov (United States)

    Kong, Lingzhu; Car, Roberto

    2013-03-01

    We use a GW approach[2] to compute the x-ray absorption spectra of model low- and high-density amorphous ice structures(LDA and HDA)[3]. We include the structural effects of quantum zero point motion using colored-noise Langevin molecular dynamics[4]. The calculated spectra differences in the main and post edge region between LDA and HDA agree well with experimental observations. We attribute these differences to the presence of interstitial molecules within the first coordination shell range in HDA. This assignment is further supported by a calculation of the spectrum of ice VIII, a high-pressure structure that maximizes the number of interstitial molecules and, accordingly, shows a much weaker post-edge feature. We further rationalize the spectral similarity between HDA and liquid water, and between LDA and ice Ih in terms of the respective similarities in the H-bond network topology and bond angle distributions. Supported by grants DOE-DE-SC0005180, DOE DE-SC0008626 and NSF-CHE-0956500.

  15. On the Constancy of the Photon Index of X-ray spectra of 4U~1728-34 through all spectral states

    CERN Document Server

    Seifina, Elena

    2011-01-01

    We present an analysis of the spectral properties observed in X-rays from Neutron Star X-ray binary 4U~1728-34 during transitions between the low and the high luminosity states when electron temperature kT_e of the Compton cloud monotonically decreases from 15 to 2.5 keV. We analyze the transition episodes from this source observed with BeppoSAX and RXTE. We find that the X-ray broad-band energy spectra of 4U~1728-34 during all spectral states can be modeled by a combination of a thermal (black body-like) component, a Comptonized component (which we herein denote COMPTB) and a Gaussian component. Spectral analysis using this model evidences that the photon power-law index Gamma is almost constant (Gamma=1.99+/-0.02) when kT_e changes from 15 to 2.5 keV during these spectral transitions. We explain this quasi-stability of the index by the model in which the spectrum is dominated by the strong thermal Comptonized component formed in the transition layer (TL) between the accretion disk and neutron star surface. ...

  16. HEXTE Studies of Sco X-1 Spectra Detections of Hard X-Ray Tails Beyond 200 keV

    CERN Document Server

    D'Amico, F; Rothschild, R E; Peterson, L E; Gruber, D E; Pelling, M R; Tomsick, J A

    2001-01-01

    Using the HEXTE experiment on-board the RXTE satellite, we performed a search for hard X-ray tails in Sco X-1 spectra. We found strong evidence for the presence of such a non-thermal component on several occasions. Using the PCA/RXTE we were able to track the position of the source along the Z diagram, and we observed that the presence of the hard X-ray tail is not confined to a particular region. However, we found a correlation between the power law index of the non-thermal component and the position of the source in the Z diagram, suggesting that the hard X-ray spectrum (i.e., E > 50 keV) becomes flatter as the mass accretion rate increases. We were also able to study the temporal variation of the appearance/absence of the hard X-ray component. With our derived luminosities, we were also able to test the idea that X-ray luminosities can be used to distinguish between X-ray binary systems containing neutron stars and black holes.

  17. Broadband Eclipse Spectra of Exoplanets are Featureless

    CERN Document Server

    Hansen, C J; Cowan, N B

    2014-01-01

    Spectral retrieval methods leverage features in emission spectra to constrain the atmospheric composition and structure of transiting exoplanets. Most of the observed emission spectra consist of broadband photometric observations at a small number of wavelengths. We compare the Bayesian Information Criterion (BIC) of blackbody fits and spectral retrieval fits for all planets with eclipse measurements in multiple thermal wavebands, typically hot Jupiters with 2-4 observations. If the published error bars are taken at face value, then eight planets are significantly better fit by a spectral model than by a blackbody. In this under-constrained regime, however, photometric uncertainties directly impact one's ability to constrain atmospheric properties. By considering the handful of planets for which eclipse measurements have been repeated and/or reanalyzed, we obtain an empirical estimate of systematic uncertainties for broadband eclipse depths obtained with the Spitzer Space Telescope: sigma_sys = 5E-4. When thi...

  18. ANALYSIS OF X-RAY SPECTRA EMITTED FROM THE VENUS ECR ION SOURCE

    Energy Technology Data Exchange (ETDEWEB)

    Benitez, J.; Leitner, D.

    2008-01-01

    The Versatile Electron Cyclotron resonance ion source for Nuclear Science (VENUS), located at Lawrence Berkeley National Lab’s 88-inch cyclotron, extracts ion beams from a plasma created by ionizing a gas with energetic electrons. Liquid-helium cooled superconducting coils produce magnetic fi elds that confi ne the plasma and high microwave frequencies heat the electrons enough to allow for successive ionizations of the neutral gas atoms. The combination of strong plasma confi nement and high microwave frequencies results in VENUS’ production of record breaking ion beam currents and high charge state distributions. While in operation, VENUS produces signifi cant quantities of bremsstrahlung, in the form of x-rays, primarily through two processes: 1) electron-ion collisions within the plasma, and 2) electrons are lost from the plasma, collide with the plasma chamber wall, and radiate bremsstrahlung due to their sudden deceleration. The bremsstrahlung deposited into the plasma chamber wall is absorbed by the cold mass used to maintain superconductivity in the magnets and poses an additional heat load on the cryostat. In order for VENUS to reach its maximum operating potential of 10 kW of 28 GHz microwave heating frequency, the heat load posed by the emitted bremsstrahlung must be understood. In addition, studying the bremsstrahlung under various conditions will help further our understanding of the dynamics within the plasma. A code has been written, using the Python programming language, to analyze the recorded bremsstrahlung spectra emitted from the extraction end of VENUS. The code outputs a spectral temperature, which is relatively indicative of the temperature of the hot electrons, and total integrated count number corresponding to each spectra. Bremsstrahlung spectra are analyzed and compared by varying two parameters: 1) the heating frequency, 18 GHz and 28 GHz, and 2) the ratio between the minimum magnetic fi eld and the resonant magnetic fi eld, .44 and

  19. X-ray magnetic circular dichroism spectra and distortions at Fe2+ L(2,3) edges

    NARCIS (Netherlands)

    Wang, X.; de Groot, F.M.F.; Cramer, S.P.

    1996-01-01

    We have shown from ligand field multiplet calculations that the shape of X-ray magnetic circular dichroism (XMCD) spectra changes drastically with the distortion parameter Ds. The temperature dependence study of XMCD makes it possible to determine both Ds and spin-orbit coupling.

  20. CALCULATION OF MAGNETIC-X-RAY DICHROISM IN 4D AND 5D ABSORPTION-SPECTRA OF ACTINIDES

    NARCIS (Netherlands)

    OGASAWARA, H; KOTANI, A; THOLE, BT

    1991-01-01

    We present atomic calculations of the magnetic dichroism in 4d and 5d x-ray-absorption (XAS) spectra of trivalent actinide ions. The calculations are carried out for both linearly and circularly polarized light at zero temperature. Large magnetic dichroism is predicted for 5d XAS with

  1. X-ray magnetic circular dichroism spectra and distortions at Fe2+ L(2,3) edges

    NARCIS (Netherlands)

    Wang, X.; de Groot, F.M.F.; Cramer, S.P.

    We have shown from ligand field multiplet calculations that the shape of X-ray magnetic circular dichroism (XMCD) spectra changes drastically with the distortion parameter Ds. The temperature dependence study of XMCD makes it possible to determine both Ds and spin-orbit coupling.

  2. Broadband monitoring tracing the evolution of the jet and disk in the black hole candidate X-ray binary MAXI J1659-152

    CERN Document Server

    van der Horst, A J; Miller-Jones, J C A; Linford, J D; Gorosabel, J; Russell, D M; Postigo, A de Ugarte; Lundgren, A A; Taylor, G B; Maitra, D; Guziy, S; Belloni, T M; Kouveliotou, C; Jonker, P G; Kamble, A; Paragi, Z; Homan, J; Kuulkers, E; Granot, J; Altamirano, D; Buxton, M M; Castro-Tirado, A; Fender, R P; Garrett, M A; Gehrels, N; Hartmann, D H; Kennea, J A; Krimm, H A; Mangano, V; Ramirez-Ruiz, E; Romano, P; Wijers, R A M J; Wijnands, R; Yang, Y J

    2013-01-01

    MAXI J1659-152 was discovered on 2010 September 25 as a new X-ray transient, initially identified as a gamma-ray burst, but was later shown to be a new X-ray binary with a black hole as the most likely compact object. Dips in the X-ray light curves have revealed that MAXI J1659-152 is the shortest period black hole candidate identified to date. Here we present the results of a large observing campaign at radio, sub-millimeter, near-infrared (nIR), optical and ultraviolet (UV) wavelengths. We have combined this very rich data set with the available X-ray observations to compile a broadband picture of the evolution of this outburst. We have performed broadband spectral modeling, demonstrating the presence of a spectral break at radio frequencies and a relationship between the radio spectrum and X-ray states. Also, we have determined physical parameters of the accretion disk and put them into context with respect to the other parameters of the binary system. Finally, we have investigated the radio-X-ray and nIR/...

  3. Evaluation of X-ray spectra transmitted by different concrete compositions

    Science.gov (United States)

    Costa, P. R.; Vieira, D. V.; Naccache, V. K.; Ferreira, K. R.; Priszkulnik, S.

    2015-11-01

    Additional shielding material must frequently be incorporated to medical facilities in order to comply with radiation protection requirements when using radiation sources. Typical materials for shielding walls, floor and ceiling are the lead, concrete and barite. In the present work, a group of four concrete compositions was evaluated by using broad beam transmission curves and transmitted spectra in the range of X-ray energies used for diagnostic imaging. The studied concretes were classified as ordinary concrete (Type C), concrete with addition of hematite (Types H1 and H2) and concrete with addition of steel grit (Type S). Concrete with steel grit shows be more efficient as shielding material of the three heavy types concrete studied. The two mixes of concrete and hematite are practically equivalent from the radioprotection point of view. However, the granulation difference between them might be important to other fields, as shielding is not the only function of concrete in the building structure. Although they are not as efficient as concrete with steel grit, they may be a shielding option in a facility with low shielding requirement.

  4. Revealing O VII from stacked X-ray grating spectra of clusters, groups and elliptical galaxies

    CERN Document Server

    Sanders, J S

    2010-01-01

    We stack 4.6 Ms of high spectral resolution XMM-Newton Reflection Grating Spectrometer spectra from galaxy clusters, groups of galaxies and elliptical galaxies. For those objects with a central temperature of less than 1 keV, we detect O VII for the first time, with a probability of false detection of 2.5x10^-4. The flux ratio of the O VII to Fe XVII lines is 1/4 to 1/8 of the emission expected for isobaric radiative cooling in the absence of heating. There is either a process preventing cooling below 0.5 keV, anomalous O/Fe abundance ratios, absorbing material around the coolest X-ray emitting gas or non-radiative cooling taking place. The mean N VII emission line is strong in the sub-keV sample. As the ratio of the hydrogenic N and O lines is largely independent of temperature, we measure a mean N/O ratio of 4.0 +- 0.6 Solar. Although the continuum around the C VI lines is difficult to measure we can similarly estimate that the C/O ratio is 0.9 +- 0.3 Solar.

  5. Monte Carlo derivation of filtered tungsten anode X-ray spectra for dose computation in digital mammography*

    Science.gov (United States)

    Paixão, Lucas; Oliveira, Bruno Beraldo; Viloria, Carolina; de Oliveira, Marcio Alves; Teixeira, Maria Helena Araújo; Nogueira, Maria do Socorro

    2015-01-01

    Objective Derive filtered tungsten X-ray spectra used in digital mammography systems by means of Monte Carlo simulations. Materials and Methods Filtered spectra for rhodium filter were obtained for tube potentials between 26 and 32 kV. The half-value layer (HVL) of simulated filtered spectra were compared with those obtained experimentally with a solid state detector Unfors model 8202031-H Xi R/F & MAM Detector Platinum and 8201023-C Xi Base unit Platinum Plus w mAs in a Hologic Selenia Dimensions system using a direct radiography mode. Results Calculated HVL values showed good agreement as compared with those obtained experimentally. The greatest relative difference between the Monte Carlo calculated HVL values and experimental HVL values was 4%. Conclusion The results show that the filtered tungsten anode X-ray spectra and the EGSnrc Monte Carlo code can be used for mean glandular dose determination in mammography. PMID:26811553

  6. A practical method for estimating high-energy X-ray spectra using the iterative perturbation principle proposed by Waggener

    CERN Document Server

    Iwasaki, A; Kubota, M; Fujimori, A; Suzaki, K; Abe, Y

    2003-01-01

    We have remodeled the X-ray spectra estimation method, originally proposed by Waggener et al. (Med. Phys. 26(1999)1269), based on the iterative perturbation technique to minimize differences between measured and calculated transmission curves using low Z attenuators. With our approach, the iterative perturbation cycle is repeated until a reasonable spectrum is obtained. Furthermore, the degree of differences between the measured and calculated transmission curves is also checked using high Z attenuators. The present experimental study, conducted using 4, 10 and 15 MV X-ray beams from a linear accelerator, demonstrated that the spectrum varies strongly with the off-axis distance.

  7. Calculation of the Kramers-Kronig transform of X-ray spectra by a piecewise Laurent polynomial method.

    Science.gov (United States)

    Watts, Benjamin

    2014-09-22

    An algorithm is presented for the calculation of the Kramers-Kronig transform of a spectrum via a piecewise Laurent polynomial method. This algorithm is demonstrated to be highly accurate, while also being computationally efficient. The algorithm places no requirements on data point spacing and is capable of integrating across the full spectrum (i.e. from zero to infinity). Further, we present a computer application designed to aid in calculating the Kramers-Kronig transform on near-edge experimental X-ray absorption spectra (extended with atomic scattering factor data) in order to produce the dispersive part of the X-ray refractive index, including near-edge features.

  8. WITS-HEX: A renovated code for analysis of PIXE X-ray spectra

    Science.gov (United States)

    Lipworth, A. D.; Annegarn, H. J.; Bauman, S.; Molokomme, T.; Walker, A. J.

    1990-04-01

    The code REX [H.C. Kaufmann and K.R. Akselsson, Adv. X-ray Anal. 18 (1975) 353] and its successor, HEX were developed at Florida State University and University of Lund in the early seventies for quantitative reduction of PIXE spectra. HEX modelled many of the physical processes, including target self-absorption. Lack of adequate documentation and several inherent software related problems hampered widespread adoption and further development. HEX was designed using a hierarchical functional design approach, coded in FORTRAN IV. Its element library and request list are tightly constrained. ANSI standard FORTRAN provides few structured constructs, nor does it support dynamic data structures. HEX has a batch mode of interaction which affords minimal (interim) user interactions. To overcome these limitations we have modernised the program to run on IBM PC compatible computers by using object-oriented design techniques, documented in Program Description Language (pseudo-code) and implemented in a modern programming language, Pascal. Turbo Pascal 5.5 provides an integrated program development environment, a high resolution graphics library, an operating system interface and many software development tools to improve programmer productivity. A menu-based highly interactive screen management library is used for the user interface. A demonstration version is available for user evaluation. Further rigorous testing and the development of user acquired spectra interfacing code will be developed before the first release. The renovated code, WITS-HEX, has extracted the intellectual value embodied in HEX. It will be inherently more stable, reliable, versatile, maintainable and easy to use to facilitate future process modifications.

  9. First-principles calculations of X-ray absorption spectra for warm dense methane

    Science.gov (United States)

    Li, Zi; Wang, Cong; Li, Dafang; Kang, Wei; Zhang, Ping

    2017-09-01

    X-ray absorption spectrum is a powerful tool for atomic structure detection on materials under extreme conditions. Here, we perform first-principles molecular dynamics and X-ray absorption spectrum calculations for warm dense methane under thermodynamical conditions along a Hugoniot curve. From the molecular dynamics trajectories, the detailed atomic structures are examined for each condition. The carbon K-shell X-ray absorption spectrum is calculated, and its change with temperature and pressure is discussed. The methane systems under extreme conditions may contain radicals CHx (x = 1,2,3), molecules CH4, and carbon chains CmHn (m,n >1). These various products show quite different contributions to the total X-ray spectrum due to the different atomic and electronic structures. The change of the total X-ray spectrum along the Hugoniot curve is then attributed to the change of the products induced by the temperature and pressure. Some clear signatures on the X-ray absorption spectrum under different thermodynamical conditions are proposed, which provide useful information for future X-ray experiments.

  10. Ab Initio Calculations of X-ray Spectra : Atomic Multiplet and Molecular Orbital Effects in a Multiconfigurational SCF Approach to the L-Edge Spectra of Transition Metal Complexes

    NARCIS (Netherlands)

    Josefsson, Ida; Kunnus, Kristjan; Schreck, Simon; Foehlisch, Alexander; de Groot, Frank; Wernet, Philippe; Odelius, Michael

    2012-01-01

    A new ab initio approach to the calculation of X-ray spectra is demonstrated. It combines a high-level quantum chemical description of the chemical interactions and local atomic multiplet effects. We show here calculated L-edge X-ray absorption (XA) and resonant inelastic X-ray scattering spectra fo

  11. Comparison between X-rays spectra and their effective energies in small animal CT tomographic imaging and dosimetry.

    Science.gov (United States)

    Hamdi, Mahdjoub; Mimi, Malika; Bentourkia, M'hamed

    2016-12-22

    Small animal CT imaging and dosimetry usually rely on X-ray radiation produced by X-ray tubes. These X-rays typically cover a large energy range. In this study, we compared poly-energetic X-ray spectra against estimated equivalent (effective) mono-energetic beams with the same number of simulated photons for small animal CT imaging and dosimetry applications. Two poly-energetic X-ray spectra were generated from a tungsten anode at 50 and 120 kVp. The corresponding effective mono-energetic beams were established as 36 keV for the 50 kVp spectrum and 49.5 keV for the 120 kVp spectrum. To assess imaging applications, we investigated the spatial resolution by a tungsten wire, and the contrast-to-noise ratio in a reference phantom and in a realistic mouse phantom. For dosimetry investigation, we calculated the absorbed dose in a segmented digital mouse atlas in the skin, fat, heart and bone tissues. Differences of 2.1 and 2.6% in spatial resolution were respectively obtained between the 50 and 120 kVp poly-energetic spectra and their respective 36 and 49.5 keV mono-energetic beams. The differences in contrast-to-noise ratio between the poly-energetic 50 kVp spectrum and its corresponding mono-energetic 36 keV beam for air, fat, brain and bone were respectively -2.9, -0.2, 11.2 and -4.8%, and similarly between the 120 kVp and its effective energy 49.5 keV: -11.3, -20.2, -4.2 and -13.5%. Concerning the absorbed dose, for the lower X-ray beam energies, 50 kVp against 36 keV, the poly-energetic radiation doses were higher than the mono-energetic doses. Instead, for the higher X-ray beam energies, 120 kVp and 49.5 keV, the absorbed dose to the bones and lungs were higher for the mono-energetic 49.5 keV. The intensity and energy of the X-ray beam spectrum have an impact on both imaging and dosimetry in small animal studies. Simulations with mono-energetic beams should take into account these differences in order to study biological effects or to be compared to

  12. AN INTEGRATED MODEL FOR THE PRODUCTION OF X-RAY TIME LAGS AND QUIESCENT SPECTRA FROM HOMOGENEOUS AND INHOMOGENEOUS BLACK HOLE ACCRETION CORONAE

    Energy Technology Data Exchange (ETDEWEB)

    Kroon, John J.; Becker, Peter A., E-mail: jkroon@gmu.edu, E-mail: pbecker@gmu.edu [Department of Physics and Astronomy, George Mason University, Fairfax, VA 22030-4444 (United States)

    2016-04-20

    Many accreting black holes manifest time lags during outbursts, in which the hard Fourier component typically lags behind the soft component. Despite decades of observations of this phenomenon, the underlying physical explanation for the time lags has remained elusive, although there are suggestions that Compton reverberation plays an important role. However, the lack of analytical solutions has hindered the interpretation of the available data. In this paper, we investigate the generation of X-ray time lags in Compton scattering coronae using a new mathematical approach based on analysis of the Fourier-transformed transport equation. By solving this equation, we obtain the Fourier transform of the radiation Green’s function, which allows us to calculate the exact dependence of the time lags on the Fourier frequency, for both homogeneous and inhomogeneous coronal clouds. We use the new formalism to explore a variety of injection scenarios, including both monochromatic and broadband (bremsstrahlung) seed photon injection. We show that our model can successfully reproduce both the observed time lags and the time-averaged (quiescent) X-ray spectra for Cyg X-1 and GX 339-04, using a single set of coronal parameters for each source. The time lags are the result of impulsive bremsstrahlung injection occurring near the outer edge of the corona, while the time-averaged spectra are the result of continual distributed injection of soft photons throughout the cloud.

  13. PROBING WOLF–RAYET WINDS: CHANDRA/HETG X-RAY SPECTRA OF WR 6

    Energy Technology Data Exchange (ETDEWEB)

    Huenemoerder, David P.; Schulz, N. S. [Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, 70 Vassar St., Cambridge, MA 02139 (United States); Gayley, K. G. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States); Hamann, W.-R.; Oskinova, L.; Shenar, T. [Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24/25, D-14476 Potsdam (Germany); Ignace, R. [Department of Physics and Astronomy, East Tennessee State University, Johnson City, TN 37614 (United States); Nichols, J. S. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., MS 34, Cambridge, MA 02138 (United States); Pollock, A. M. T., E-mail: dph@space.mit.edu, E-mail: ken.gayley@gmail.com, E-mail: wrh@astro.physik.uni-potsdam.de, E-mail: lida@astro.physik.uni-potsdam.de, E-mail: shtomer@astro.physik.uni-potsdam.de, E-mail: ignace@mail.etsu.edu, E-mail: jnichols@cfa.harvard.edu [European Space Agency, ESAC, Apartado 78, E-28691 Villanueva de la Cañada (Spain)

    2015-12-10

    With a deep Chandra/HETGS exposure of WR 6, we have resolved emission lines whose profiles show that the X-rays originate from a uniformly expanding spherical wind of high X-ray-continuum optical depth. The presence of strong helium-like forbidden lines places the source of X-ray emission at tens to hundreds of stellar radii from the photosphere. Variability was present in X-rays and simultaneous optical photometry, but neither were correlated with the known period of the system or with each other. An enhanced abundance of sodium revealed nuclear-processed material, a quantity related to the evolutionary state of the star. The characterization of the extent and nature of the hot plasma in WR 6 will help to pave the way to a more fundamental theoretical understanding of the winds and evolution of massive stars.

  14. Galaxy Cluster Thermal X-Ray Spectra Constrain Axion-Like Particles

    CERN Document Server

    Conlon, Joseph P; Powell, Andrew J

    2015-01-01

    Axion-like particles (ALPs) and photons inter-convert in the presence of a magnetic field. At keV energies in the environment of galaxy clusters, the conversion probability can become unsuppressed for light ALPs. Conversion of thermal X-ray photons into ALPs can introduce a step-like feature into the cluster thermal bremsstrahlung spectrum, and we argue that existing X-ray data on galaxy clusters should be sufficient to extend bounds on ALPs in the low-mass region $m_a \\lesssim 1 \\times 10^{-12}\\,{\\rm eV}$ down to $M \\sim 7\\times 10^{11}\\, {\\rm GeV}$, and that for $10^{11}\\, {\\rm GeV} < M \\lesssim 10^{12}$ GeV light ALPs give rise to interesting and unique observational signatures that may be probed by existing and upcoming X-ray (and potentially X-ray polarisation) observations of galaxy clusters.

  15. Comptomization and radiation spectra of X-ray sources. Calculation of the Monte Carlo method

    Science.gov (United States)

    Pozdnyakov, L. A.; Sobol, I. M.; Sonyayev, R. A.

    1980-01-01

    The results of computations of the Comptomization of low frequency radiation in weakly relativistic plasma are presented. The influence of photoabsorption by iron ions on a hard X-ray spectrum is considered.

  16. Broad-band spectroscopy of the transient X-ray binary pulsar KS 1947+300 during 2013 giant outburst: Detection of pulsating soft X-ray excess component

    CERN Document Server

    Epili, Prahlad; Jaisawal, Gaurava K

    2016-01-01

    We present the results obtained from detailed timing and spectral studies of the Be/X-ray binary pulsar KS 1947+300 during its 2013 giant outburst. We used data from Suzaku observations of the pulsar at two epochs i.e. on 2013 October 22 (close to the peak of the outburst) and 2013 November 22. X-ray pulsations at $\\sim$18.81 s were clearly detected in the light curves obtained from both observations. Pulse periods estimated during the outburst showed that the pulsar was spinning up. The pulse profile was found to be single-peaked up to $\\sim$10 keV beyond which a sharp peak followed by a dip-like feature appeared at hard X-rays. The dip-like feature has been observed up to $\\sim$70 keV. The 1-110 keV broad-band spectroscopy of both observations revealed that the best-fit model comprised of a partially absorbed Negative and Positive power law with EXponential cutoff (NPEX) continuum model along with a blackbody component for the soft X-ray excess and two Gaussian functions at 6.4 and 6.7 keV for emission line...

  17. X-Ray Absorption with Transmission X-Ray Microscopes

    NARCIS (Netherlands)

    de Groot, F.M.F.

    2016-01-01

    In this section we focus on the use of transmission X-ray microscopy (TXM) to measure the XAS spectra. In the last decade a range of soft X-ray and hard X-ray TXM microscopes have been developed, allowing the measurement of XAS spectra with 10–100 nm resolution. In the hard X-ray range the TXM

  18. Si XII X-ray Satellite Lines in Solar Flare Spectra

    Science.gov (United States)

    Phillips, K. J.; Sylwester, J.; Sylwester, B.; Dubau, J.

    2005-05-01

    We demonstrate the temperature dependence of the intensity ratio of dielectronic satellite lines due to Li-like Si (Si XII) to nearby He-like Si (Si XIII) 1s2 - 1snp(n=3, 4, 5) lines emitted in solar flare X-ray spectra. These lines, which occur in the wavelength range 5.253~Å--5.818~Å, have been observed by the RESIK bent crystal spectrometer on the Russian CORONAS-F solar mission. Line features made up of several strong satellites with transitions 1s2 n'l' - 1s n'l' nl lie near the `parent' Si XIII lines, transition 1s2 1S0 - 1snp 1P1; thus, the feature at 5.818~Å is made up of several blended Si XII satellites with `spectator' electrons n'l'=2s or 2p and nl=3p or 3d, and lies on the long-wavelength side of the Si XIII 1s2 - 1s3p line at 5.681~Å. A similar n=4 satellite feature at 5.565~Å is on the long-wavelength side of the Si XIII 1s2 - 1s4p line at 5.384~Å. The Si XII satellites are formed by dielectronic recombination and direct (inner-shell) excitation. The ratio Is/IHe (Is = Si XII satellite line flux, IHe = Si XIII line flux) depends on electron temperature approximately as Te-1. The atomic data needed to calculate Is/IHe for individual n=3 and n=4 Si XII satellite lines have been calculated and will be presented in this paper; excitation mechanisms including those by dielectronic recombination and inner-shell excitation were included using the SUPERSTRUCTURE and Distorted Wave formalisms. With these and theoretical fluxes of the Si XIII lines, synthetic spectra were calculated and compared with RESIK solar flare spectra. Values of Is/IHe measured from RESIK spectra during the decay of four long-duration solar flares, together with temperatures estimated both from the ratio of the GOES channels and from the ratio of total fluxes in two of the four RESIK channels, enable a comparison to be made with theoretical curves. The agreement with the theoretical curve based on synthetic spectra is within expected uncertainties, and the Te-1 dependence is

  19. Comparison of simulated and measured spectra from an X-ray tube for the energies between 20 and 35 keV

    Science.gov (United States)

    Yücel, M.; Emirhan, E.; Bayrak, A.; Ozben, C. S.; Yücel, E. Barlas

    2015-11-01

    Design and production of a simple and low cost X-ray imaging system that can be used for light industrial applications was targeted in the Nuclear Physics Laboratory of Istanbul Technical University. In this study, production, transmission and detection of X-rays were simulated for the proposed imaging device. OX/70-P dental tube was used and X-ray spectra simulated by Geant4 were validated by comparison with X-ray spectra measured between 20 and 35 keV. Relative detection efficiency of the detector was also determined to confirm the physics processes used in the simulations. Various time optimization tools were performed to reduce the simulation time.

  20. Comparison of simulated and measured spectra from an X-ray tube for the energies between 20 and 35 keV

    Energy Technology Data Exchange (ETDEWEB)

    Yücel, M.; Emirhan, E.; Bayrak, A.; Ozben, C.S.; Yücel, E. Barlas, E-mail: barlase@itu.edu.tr

    2015-11-01

    Design and production of a simple and low cost X-ray imaging system that can be used for light industrial applications was targeted in the Nuclear Physics Laboratory of Istanbul Technical University. In this study, production, transmission and detection of X-rays were simulated for the proposed imaging device. OX/70-P dental tube was used and X-ray spectra simulated by Geant4 were validated by comparison with X-ray spectra measured between 20 and 35 keV. Relative detection efficiency of the detector was also determined to confirm the physics processes used in the simulations. Various time optimization tools were performed to reduce the simulation time.

  1. Soft X-ray absorption spectra of aqueous salt solutions with highly charged cations in liquid microjets

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, Craig P.; Uejio, Janel S.; Duffin, Andrew M.; Drisdell, Walter S.; Smith, Jared D.; Saykally, Richard J.

    2010-03-11

    X-ray absorption spectra of 1M aqueous solutions of indium (III) chloride, yttrium (III) bromide, lanthanum (III) chloride, tin (IV) chloride and chromium (III) chloride have been measured at the oxygen K-edge. Relatively minor changes are observed in the spectra compared to that of pure water. SnCl{sub 4} and CrCl{sub 3} exhibit a new onset feature which is attributed to formation of hydroxide or other complex molecules in the solution. At higher energy, only relatively minor, but salt-specific changes in the spectra occur. The small magnitude of the observed spectral changes is ascribed to offsetting perturbations by the cations and anions.

  2. BROADBAND X-RAY IMAGING AND SPECTROSCOPY OF THE CRAB NEBULA AND PULSAR WITH NuSTAR

    Energy Technology Data Exchange (ETDEWEB)

    Madsen, Kristin K.; Harrison, Fiona; Grefenstette, Brian W. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Reynolds, Stephen [Physics Department, NC State University, Raleigh, NC 27695 (United States); An, Hongjun [Department of Physics, McGill University, Montreal, Quebec, H3A 2T8 (Canada); Boggs, Steven; Craig, William W.; Zoglauer, Andreas [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Christensen, Finn E. [DTU Space, National Space Institute, Technical University of Denmark, Elektronvej 327, DK-2800 Lyngby (Denmark); Fryer, Chris L. [CCS-2, Los Alamos National Laboratory, Livermore, CA 94550 (United States); Hailey, Charles J.; Nynka, Melania [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Markwardt, Craig; Zhang, William [Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

    2015-03-01

    We present broadband (3-78 keV) NuSTAR X-ray imaging and spectroscopy of the Crab nebula and pulsar. We show that while the phase-averaged and spatially integrated nebula + pulsar spectrum is a power law in this energy band, spatially resolved spectroscopy of the nebula finds a break at ∼9 keV in the spectral photon index of the torus structure with a steepening characterized by ΔΓ ∼ 0.25. We also confirm a previously reported steepening in the pulsed spectrum, and quantify it with a broken power law with break energy at ∼12 keV and ΔΓ ∼ 0.27. We present spectral maps of the inner 100'' of the remnant and measure the size of the nebula as a function of energy in seven bands. These results find that the rate of shrinkage with energy of the torus size can be fitted by a power law with an index of γ = 0.094 ± 0.018, consistent with the predictions of Kennel and Coroniti. The change in size is more rapid in the NW direction, coinciding with the counter-jet where we find the index to be a factor of two larger. NuSTAR observed the Crab during the latter part of a γ-ray flare, but found no increase in flux in the 3-78 keV energy band.

  3. Broadband X-ray Imaging and Spectroscopy of the Crab Nebula and Pulsar with NuSTAR

    CERN Document Server

    Madsen, Kristin K; Harrison, Fiona; An, Hongjun; Boggs, Steven; Christensen, Finn E; Craig, William W; Fryer, Chris L; Grefenstette, Brian W; Hailey, Charles J; Markwardt, Craig; Nynka, Melania; Stern, Daniel; Zoglauer, Andreas; Zhang, William

    2015-01-01

    We present broadband (3 -- 78 keV) NuSTAR X-ray imaging and spectroscopy of the Crab nebula and pulsar. We show that while the phase-averaged and spatially integrated nebula + pulsar spectrum is a power-law in this energy band, spatially resolved spectroscopy of the nebula finds a break at $\\sim$9 keV in the spectral photon index of the torus structure with a steepening characterized by $\\Delta\\Gamma\\sim0.25$. We also confirm a previously reported steepening in the pulsed spectrum, and quantify it with a broken power-law with break energy at $\\sim$12 keV and $\\Delta\\Gamma\\sim0.27$. We present spectral maps of the inner 100\\as\\ of the remnant and measure the size of the nebula as a function of energy in seven bands. These results find that the rate of shrinkage with energy of the torus size can be fitted by a power-law with an index of $\\gamma = 0.094\\pm 0.018$, consistent with the predictions of Kennel and Coroniti (1984). The change in size is more rapid in the NW direction, coinciding with the counter-jet w...

  4. Broadband multilayer soft X-ray mirrors for attosecond pulse formation at photon energies above 100 eV

    Energy Technology Data Exchange (ETDEWEB)

    Hofstetter, Michael; Schuster, Joerg; Kleineberg, Ulf [LMU, Physik (Germany); Aquila, Andrew [CXRO (United States); Schulze, Martin; Fiess, Markus; Gouliemakis, Eleftherios; Krausz, Ferenc [MPQ (Germany); Huth, Martin [LMU, Chemie (Germany)

    2009-07-01

    We report on the development, fabrication and application of multilayer mirrors as broadband soft-X-ray optical components for the formation of attosecond (1 asec=10{sup -18}s)pulses from high harmonic radiation. Until recently, attosecond physics was merely confined to the photon energy range below 100 eV due to the properties of Mo/Si multilayer and single isolated pulses of 80 asec pulse duration have been achieved. For many applications, e.g. in the characterization of the photoemission dynamics from solid surfaces or the characterization of ultrafast surface plasmon dynamics in metallic nanostructures by attosecond pump-probe spectroscopy, higher photon energies are desirable to address deeper bound electronic core states or to increase the kinetic energy of the emitted photoelectrons. Here, we introduce new aperiodic broad bandwidth multilayer systems based on lanthanum (e.g. LaMo, LaB{sub 4}CMo, LaB{sub 4}C, MoB{sub 4}C),for the 100-190 eV photon energy range. Multilayer properties like interface roughness, interlayer formation and reflectivity are discussed. Finally, first applications for spectral filtering of the HHG comb above 100 eV are presented.

  5. H-alpha spectra of dynamic chromospheric processes in five well-observed X-ray flares

    Science.gov (United States)

    Canfield, Richard C.; Penn, Matthew J.; Wulser, Jean-Pierre; Kiplinger, Alan L.

    1990-01-01

    Simultaneous H-alpha and hard X-ray (HXR) spectra were obtained for five solar flares to determine the relationship of H-alpha profiles and the nonthermal part of the flare represented by the hard X-ray burst. All five flares exhibited impulsive-phase redshifted H-alpha in emission, which was temporarily and spatially associated with intense HXR emission and broad impulsive-phase H-alpha wings. A few small regions within two flares showed a blueshifted H-alpha emission which appeared only early in the impulsive phase and was temporally correlated with the HXR emission but not with broad H-alpha wings. Finally, there were both redshifted and blueshifted absorption spectra with properties fully consistent with those known for erupting and untwisting filaments.

  6. First-Principles Calculation of Principal Hugoniot and K-Shell X-ray Absorption Spectra for Warm Dense KCl

    CERN Document Server

    Zhao, Shijun; Kang, Wei; Li, Zi; Zhang, Ping; He, Xian-Tu

    2015-01-01

    Principal Hugoniot and K-shell X-ray absorption spectra of warm dense KCl are calculated using the first-principles molecular dynamics method. Evolution of electronic structures as well as the influence of the approximate description of ionization on pressure (caused by the underestimation of the energy gap between conduction bands and valence bands) in the first-principles method are illustrated by the calculation. Pressure ionization and thermal smearing are shown as the major factors to prevent the deviation of pressure from global accumulation along the Hugoniot. In addition, cancellation between electronic kinetic pressure and virial pressure further reduces the deviation. The calculation of X-ray absorption spectra shows that the band gap of KCl persists after the pressure ionization of the $3p$ electrons of Cl and K taking place at lower energy, which provides a detailed understanding to the evolution of electronic structures of warm dense matter.

  7. Exploring the Physics of Type Ia Supernovae Through the X-ray Spectra of their Remnants

    CERN Document Server

    Badenes, C; Bravo, E; Hughes, J P; Hwang, U

    2005-01-01

    We present the results of an ongoing project to use the X-ray observations of Type Ia Supernova Remnants to constrain the physical processes involved in Type Ia Supernova explosions. We use the Tycho Supernova Remnant (SN 1572) as a benchmark case, comparing its observed spectrum with models for the X-ray emission from the shocked ejecta generated from different kinds of Type Ia explosions. Both the integrated spectrum of Tycho and the spatial distribution of the Fe and Si emission in the remnant are well reproduced by delayed detonation models with stratified ejecta. All the other Type Ia explosion models fail, including well-mixed deflagrations calculated in three dimensions.

  8. Measuring the shock-heating rate in the winds of O stars using X-ray line spectra

    CERN Document Server

    Cohen, David H; Gayley, Kenneth G; Owocki, Stanley P; Sundqvist, Jon O; Petit, Veronique; Leutenegger, Maurice A

    2014-01-01

    We present a new method for using measured X-ray emission line fluxes from O stars to determine the shock-heating rate due to instabilities in their radiation-driven winds. The high densities of these winds means that their embedded shocks quickly cool by local radiative emission, while cooling by expansion should be negligible. Ignoring for simplicity any non-radiative mixing or conductive cooling, the method presented here exploits the idea that the cooling post-shock plasma systematically passes through the temperature characteristic of distinct emission lines in the X-ray spectrum. In this way, the observed flux distribution among these X-ray lines can be used to construct the cumulative probability distribution of shock strengths that a typical wind parcel encounters as it advects through the wind. We apply this new method (Gayley 2014) to Chandra grating spectra from five O stars with X-ray emission indicative of embedded wind shocks in effectively single massive stars. Correcting for wind absorption of...

  9. Constraining black hole masses in low-accreting AGN using X-ray spectra

    CERN Document Server

    Jang, I; Hughes, C; Titarchuk, L

    2014-01-01

    In a recent work we demonstrated that a novel X-ray scaling method, originally introduced for Galactic black holes (GBHs), can be reliably extended to estimate the mass of supermassive black holes accreting at a moderate to high level. Here we investigate the limits of applicability of this method to low-accreting active galactic nuclei, using a control sample with good-quality X-ray data and dynamically measured mass. For low-accreting AGNs, because the basic assumption that the photon index positively correlates with the accretion rate no longer holds the X-ray scaling method cannot be used. Nevertheless, the inverse correlation in the Gamma-Lx/LEdd diagram, found in several low-accreting black holes and confirmed by this sample, can be used to constrain black hole mass within a factor of ~10 from the dynamically determined values. We provide a simple recipe to determine black hole mass using solely X-ray spectral data, which can be used as a sanity check for black hole mass determination based on indirect ...

  10. MAGNETIC-X-RAY DICHROISM - GENERAL FEATURES OF DIPOLAR AND QUADRUPOLAR SPECTRA

    NARCIS (Netherlands)

    CARRA, P; KONIG, H; THOLE, BT; ALTARELLI, M

    1993-01-01

    Sum rules are derived for dipolar linear and quadrupolar circular dichroism in the X-ray region. They relate the intensity of the dichroic signal to the ground state expectation values of orbital and spin dependent effective operators, which act on the valence electrons. The results obtained are

  11. Excitation of XPS spectra from nanoscaled particles by local generation of x-rays

    Energy Technology Data Exchange (ETDEWEB)

    Mallinson, Christopher F.; Castle, James E., E-mail: J.castle@surrey.ac.uk [The Surface Analysis Laboratory, Department of Mechanical Engineering Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom)

    2015-09-15

    In preliminary work, the authors have shown that use of an aluminum substrate to support a distribution of copper particles enables their characteristic photoelectrons to be observed within the Auger electron spectrum generated by an incident electron beam. This observation raises the possibility of the use of chemical shifts and the corresponding Auger parameter to identify the chemical states present on the surface of individual submicrometer particles within a mixture. In this context, the technique has an advantage in that, unlike conventional Auger electron spectroscopy, the electron beam does not dwell on the particle but on the substrate adjacent to it. Given the importance, for both medical and toxicological reasons, of the surface composition of such particles, the authors have continued to explore the potential of this development. In this contribution, the authors show that proximal excitation of x-rays is equally successful with magnesium substrates. In some regions of the x-ray photoelectron spectrum, the much larger Auger peaks generated by the electron beam can cause inconvenient clustering of Auger and photoelectron peaks. As in conventional x-ray photoelectron spectroscopy, the ability to switch between Al and Mg sources is useful in such situations. In this context, the authors have extended the studies to iron particles where the authors show that use of Al or Mg substrates, as necessary, can make a contribution to clear identification of individual components in the Fe 2p peaks. For this development in electron spectroscopy to achieve its full potential, it is necessary to optimize the beam conditions used to generate the local x-ray to give good selectivity of a given particle. Measurements made in support of this will be given. Of greater concern is a possible problem of local heating associated with x-ray generation. The authors continue to explore this problem and report some progress in minimizing heating of the particle while maintaining

  12. Analysis of X-ray Spectra of High-Z Elements obtained on Nike with high spectral and spatial resolution

    Science.gov (United States)

    Aglitskiy, Yefim; Weaver, J. L.; Karasik, M.; Serlin, V.; Obenschain, S. P.; Ralchenko, Yu.

    2014-10-01

    The spectra of multi-charged ions of Hf, Ta, W, Pt, Au and Bi have been studied on Nike krypton-fluoride laser facility with the help of two kinds of X-ray spectrometers. First, survey instrument covering a spectral range from 0.5 to 19.5 angstroms which allows simultaneous observation of both M- and N- spectra of above mentioned elements with high spectral resolution. Second, an imaging spectrometer with interchangeable spherically bent Quartz crystals that added higher efficiency, higher spectral resolution and high spatial resolution to the qualities of the former one. Multiple spectral lines with X-ray energies as high as 4 keV that belong to the isoelectronic sequences of Fe, Co, Ni, Cu and Zn were identified with the help of NOMAD package developed by Dr. Yu. Ralchenko and colleagues. In our continuous effort to support DOE-NNSA's inertial fusion program, this campaign covered a wide range of plasma conditions that result in production of relatively energetic X-rays. Work supported by the US DOE/NNSA.

  13. The X-ray spectra of optically selected Seyfert 2 galaxies. Are there any Sy2 galaxies with no absorption?

    CERN Document Server

    Pappa, A; Stewart, G C; Zezas, A L

    2001-01-01

    We present an X-ray spectral analysis of a sample of 8 bona-fide Seyfert 2 galaxies, selected on the basis of their high $[OIII]\\lambda5007$ flux, from the Ho et al. (1997) spectroscopic sample of nearby galaxies. We find that, in general, the X-ray spectra of our Seyfert 2 galaxies are complex, with some our objects having spectra different from the 'typical' spectrum of X-ray selected Seyfert 2 galaxies. Two (NGC3147 and NGC4698) show no evidence for intrinsic absorption. We suggest this is due to the fact that when the torus suppresses the intrinsic medium and hard energy flux, underlying emission from the host galaxy, originating in circumnuclear starbursts, and scattering from warm absorbers contributes in these energy bands more significantly. Our asca data alone cannot discriminate whether low absorption objects are Compton-thick AGN with a strong scattered component or lack an obscuring torus. The most striking example of our low absorption Seyfert 2 is NGC4698. Its spectrum could be explained by eith...

  14. X-Ray Polarimetry

    CERN Document Server

    Kaaret, Philip

    2014-01-01

    We review the basic principles of X-ray polarimetry and current detector technologies based on the photoelectric effect, Bragg reflection, and Compton scattering. Recent technological advances in high-spatial-resolution gas-filled X-ray detectors have enabled efficient polarimeters exploiting the photoelectric effect that hold great scientific promise for X-ray polarimetry in the 2-10 keV band. Advances in the fabrication of multilayer optics have made feasible the construction of broad-band soft X-ray polarimeters based on Bragg reflection. Developments in scintillator and solid-state hard X-ray detectors facilitate construction of both modular, large area Compton scattering polarimeters and compact devices suitable for use with focusing X-ray telescopes.

  15. A physical parameter method for the design of broad-band X-ray imaging systems to do coronal plasma diagnostics

    Science.gov (United States)

    Kahler, S.; Krieger, A. S.

    1978-01-01

    The technique commonly used for the analysis of data from broad-band X-ray imaging systems for plasma diagnostics is the filter ratio method. This requires the use of two or more broad-band filters to derive temperatures and line-of-sight emission integrals or emission measure distributions as a function of temperature. Here an alternative analytical approach is proposed in which the temperature response of the imaging system is matched to the physical parameter being investigated. The temperature response of a system designed to measure the total radiated power along the line of sight of any coronal structure is calculated. Other examples are discussed.

  16. X-ray magnetic and natural circular dichroism from first principles: Calculation of K - and L1-edge spectra

    Science.gov (United States)

    Bouldi, N.; Vollmers, N. J.; Delpy-Laplanche, C. G.; Joly, Y.; Juhin, A.; Sainctavit, Ph.; Brouder, Ch.; Calandra, M.; Paulatto, L.; Mauri, F.; Gerstmann, U.

    2017-08-01

    An efficient first-principles approach to calculate x-ray magnetic circular dichroism (XMCD) and x-ray natural circular dichroism (XNCD) is developed and applied in the near-edge region at the K and L1 edges in solids. Computation of circular dichroism requires precise calculations of x-ray absorption spectra (XAS) for circularly polarized light. For the derivation of the XAS cross section, we used a relativistic description of the photon-electron interaction that results in an additional term in the cross section that couples the electric dipole operator with an operator σ .(ɛ ×r ) that we call the spin position operator. The numerical method relies on pseudopotentials, on the gauge including projected augmented-wave method, and on a collinear spin relativistic description of the electronic structure. We apply the method to calculations of K -edge XMCD spectra of ferromagnetic iron, cobalt, and nickel and of I L1-edge XNCD spectra of α -LiIO3 , a compound with broken inversion symmetry. For XMCD spectra we find that, even if the electric dipole term is the dominant one, the electric quadrupole term is not negligible (8% in amplitude in the case of iron). The term coupling the electric dipole operator with the spin-position operator is significant (28% in amplitude in the case of iron). We obtain a sum rule relating this term to the spin magnetic moment of the p states. In α -LiIO3 we recover the expected angular dependence of the XNCD spectra.

  17. Monte Carlo derivation of filtered tungsten anode X-ray spectra for dose computation in digital mammography

    Energy Technology Data Exchange (ETDEWEB)

    Paixao, L.; Oliveira, B. B.; Nogueira, M. do S. [Centro de Desenvolvimento da Tecnologia Nuclear, Post-graduation in Science and Technology of Radiations, Minerals and Materials, Pte. Antonio Carlos 6.627, Pampulha, 31270-901 Belo Horizonte (Brazil); Viloria, C. [UFMG, Departamento de Engenharia Nuclear, Post-graduation in Nuclear Sciences and Techniques, Pte. Antonio Carlos 6.627, Pampulha, 31270-901 Belo Horizonte (Brazil); Alves de O, M. [UFMG, Department of Anatomy and Imaging, Prof. Alfredo Balena 190, 30130-100 Belo Horizonte (Brazil); Araujo T, M. H., E-mail: lpr@cdtn.br [Dr Maria Helena Araujo Teixeira Clinic, Guajajaras 40, 30180-100 Belo Horizonte (Brazil)

    2014-08-15

    It is widely accepted that the mean glandular dose (D{sub G}) for the glandular tissue is the more useful magnitude for characterizing the breast cancer risk. The procedure to estimate the D{sub G}, for being difficult to measure it directly in the breast, it is to make the use of conversion factors that relate incident air kerma (K{sub i}) at this dose. Generally, the conversion factors vary with the x-ray spectrum half-value layer and the breast composition and thickness. Several authors through computer simulations have calculated such factors by the Monte Carlo (Mc) method. Many spectral models for D{sub G} computer simulations purposes are available in the diagnostic range. One of the models available generates unfiltered spectra. In this work, the Monte Carlo EGSnrc code package with the C++ class library (eg spp) was employed to derive filtered tungsten x-ray spectra used in digital mammography systems. Filtered spectra for rhodium and aluminium filters were obtained for tube potentials between 26 and 32 kV. The half-value layer of simulated filtered spectra were compared with those obtained experimentally with a solid state detector Unfors model 8202031-H Xi R/F and Mam Detector Platinum and 8201023-C Xi Base unit Platinum Plus w m As in a Hologic Selenia Dimensions system using a Direct Radiography mode. Calculated half-value layer values showed good agreement compared to those obtained experimentally. These results show that the filtered tungsten anode x-ray spectra and the EGSnrc Mc code can be used for D{sub G} determination in mammography. (Author)

  18. On the power spectra of the wind-fed X-ray binary pulsar GX 301 - 2

    Science.gov (United States)

    Orlandini, Mauro; Morfill, G. E.

    1992-01-01

    A phenomenological model of accretion which is applied to the wind-fed X-ray binary pulsar GX 301 - 2 is developed, assuming that the accretion onto the neutron star does not occur from a continuous flux of plasma, but from blobs of matter which are threaded by the magnetic field lines onto the magnetic polar caps of the neutron star. These 'lumps' are produced at the magnetospheric limit by magnetohydrodynamical instability, introducing a 'noise' in the accretion process, due to the discontinuity in the flux of matter onto the neutron star. This model is able to describe the change of slope observed in the continuum component of the power spectra of the X-ray binary pulsar GX 301 - 2, in the frequency range 0.01 - 0.1 Hz. The physical properties of the infalling blobs derived in the model are in agreement with the constraints imposed by observations.

  19. X-ray spectra and electronic structure of the Ca3Ga2Ge3О12 compound

    Science.gov (United States)

    Shcherba, I. D.; Kostyk, L. V.; Noga, H.; Bekenov, L. V.; Uskokovich, D.; Jatsyk, B. M.

    2017-09-01

    The band structure of Ca3Ga2Ge3О12 with the garnet structure has been determined for the first time by X-ray emission and photoelectron spectroscopy. It has been established that the bottom of the valence band is formed by Ge d states, which are not dominant in the chemical bonding. Strong hybridization of oxygen 2s states with 4p states of Ga and Ge revealed by the presence of an extra structure in the X-ray emission spectra has been found. The middle of the valence band has been demonstrated to be occupied by d states of Ga, while Ga and Ge 4рstates with a considerable admixture of oxygen 2p states form the top of the valence band.

  20. Signatures of X-ray reverberation in the power spectra of AGN

    CERN Document Server

    Papadakis, I; Dovciak, M; Epitropakis, A; Emmanoulopoulos, D; Karas, V

    2016-01-01

    We compute fully relativistic disc response functions in the case of the "lamp-post" geometry using the full observed reflection spectrum for various X-ray source heights, disc inclination, and spin values of the central black hole. Since the observed PSD is equal to the product of the intrinsic power spectrum with the "transfer function" (i.e. the Fourier transform of the disc response function), we are able to predict the observed PSDs in the case of X-ray illumination of the inner disc. The observed PSD should show a prominent dip at high frequencies and an oscillatory behaviour, with a decreasing amplitude, at higher frequencies. The reverberation "echo" features should be more prominent in energy bands where the reflection component is more pronounced. The frequency of the dip is independent of energy, and it is mainly determined by the black hole mass and the X-ray source height. The amplitude of the dip increases with increasing black hole spin and inclination angle, as long as the height of the "lamp"...

  1. Autonomous Modelling of X-ray Spectra Using Robust Global Optimization Methods

    Science.gov (United States)

    Rogers, Adam; Safi-Harb, Samar; Fiege, Jason

    2015-08-01

    The standard approach to model fitting in X-ray astronomy is by means of local optimization methods. However, these local optimizers suffer from a number of problems, such as a tendency for the fit parameters to become trapped in local minima, and can require an involved process of detailed user intervention to guide them through the optimization process. In this work we introduce a general GUI-driven global optimization method for fitting models to X-ray data, written in MATLAB, which searches for optimal models with minimal user interaction. We directly interface with the commonly used XSPEC libraries to access the full complement of pre-existing spectral models that describe a wide range of physics appropriate for modelling astrophysical sources, including supernova remnants and compact objects. Our algorithm is powered by the Ferret genetic algorithm and Locust particle swarm optimizer from the Qubist Global Optimization Toolbox, which are robust at finding families of solutions and identifying degeneracies. This technique will be particularly instrumental for multi-parameter models and high-fidelity data. In this presentation, we provide details of the code and use our techniques to analyze X-ray data obtained from a variety of astrophysical sources.

  2. Correction of diagnostic x-ray spectra measured with CdTe and CdZnTe detectors

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, M. [Osaka Univ., Suita (Japan). Medical School; Kanamori, H.; Toragaito, T.; Taniguchi, A.

    1996-07-01

    We modified the formula of stripping procedure presented by E. Di. Castor et al. We added the Compton scattering and separated K{sub {alpha}} radiation of Cd and Te (23 and 27keV, respectively). Using the new stripping procedure diagnostic x-ray spectra (object 4mm-Al) of tube voltage 50kV to 100kV for CdTe and CdZnTe detectors are corrected with comparison of those spectra for the Ge detector. The corrected spectra for CdTe and CdZnTe detectors coincide with those for Ge detector at lower tube voltage than 70kV. But the corrected spectra at higher tube voltage than 70kV do not coincide with those for Ge detector. The reason is incomplete correction for full energy peak efficiencies of real CdTe and CdZnTe detectors. (J.P.N.)

  3. SU-E-I-76: Matching Primary and Scattered X-Ray Spectra for Use in Calculating the Diagnostic Radiation Index of Protection

    Energy Technology Data Exchange (ETDEWEB)

    Pasciak, A [University of Tennessee Medical Center, Knoxville, TN (United States); Jones, A [MD Anderson Cancer Center, Houston, TX (United States); Wagner, L [UT Medical School, Houston, TX (United States)

    2014-06-01

    Purpose: Lightweight lead-free or lead-composite protective garments exploit k-edge interactions to attenuate scattered X-rays. Manufacturers specify the protective value of garments in terms of lead equivalence at a single kVp. This is inadequate, as the protection provided by such garments varies with radiation quality in different use conditions. We present a method for matching scattered X-ray spectra to primary X-ray spectra. The resulting primary spectra can be used to measure penetration through protective garments, and such measurements can be weighted and summed to determine a Diagnostic Radiation Index for Protection (DRIP). Methods: Scattered X-ray spectra from fluoroscopic procedures were modeled using Monte Carlo techniques in MCNP-X 2.7. Data on imaging geometry, operator position, patient size, and primary beam spectra were gathered from clinical fluoroscopy procedures. These data were used to generate scattered X-ray spectra resulting from procedural conditions. Technical factors, including kV and added filtration, that yielded primary X-ray spectra that optimally matched the generated scattered X-ray spectra were identified through numerical optimization using a sequential quadratic programming (SQP) algorithm. Results: The primary spectra generated with shape functions matched the relative flux in each bin of the scattered spectra within 5%, and half and quarter-value layers matched within 0.1%. The DRIP for protective garments can be determined by measuring the penetration through protective garments using the matched primary spectra, then calculating a weighted average according to the expected clinical use of the garment. The matched primary spectra are specified in terms of first and second half-value layers in aluminum and acrylic. Conclusion: Lead equivalence is inadequate for completely specifying the protective value of garments. Measuring penetration through a garment using full scatter conditions is very difficult. The primary spectra

  4. X-Ray Spectra of Young Pulsars and Their Wind Nebulae: Dependence on Spin-Down Energy Loss Rate

    Science.gov (United States)

    Gotthelf, E. V.

    2003-01-01

    An observational model is presented for the spectra of young rotation-powered pulsars and their nebulae based on a study of nine bright Crab-like pulsar systems observed with the Chandra X-ray observatory. A significant correlation is discovered between the X-ray spectra of these pulsars and that of their associated pulsar wind nebulae, both of which are observed to be a function of the spin-down energy loss rate, E. The 2-10 keV spectra of these objects are well characterized by an absorbed power-law model with photon indices, Gamma, in the range of 0.6 < Gamma (sub PSR) < 2.1 and 1.3 < Gamma(sub PWN) < 2.3, for the pulsars and their nebulae, respectively. A linear regression fit relating these two sets of indexes yields Gamma(sub PWN) = 0.91 +/- 0.18 + (0.66 +/- 0.11) Gamma (sub PSR), with a correlation coefficient of r = 0.97. The spectra of these pulsars are found to steepen as Gamma = Gamma(sub max) + alpha E (exp -1/2), with Gamma(sub max) providing an observational limit on the spectral slopes of young rotation-powered pulsars. These results reveal basic properties of young pulsar systems, allow new observational constraints on models of pulsar wind emission, and provide a means of predicting the energetics of pulsars lacking detected pulsations.

  5. Broad-band BeppoSAX observation of the low-mass X-ray binary X1822-371

    CERN Document Server

    Parmar, A N; Del Sordo, S; Segreto, A; Santangelo, A; Dal Fiume, D; Orlandini, M

    2000-01-01

    Results of a 1997 September 9-10 BeppoSAX observation of the 5.57 hr low-mass X-ray binary (LMXRB) X1822-371 are presented. The 0.3-40 keV spectrum is unusually complex and cannot be fit by any of the standard models applied to other LMXRB. At least two components are required. One component has a shape consistent with that expected from the Comptonization of an input soft (Wein) spectrum while the other, contributing ~40% of the 1-10 keV flux, is consistent with being a blackbody. In addition, there is a ``dip'' in the spectrum which can be modeled by a 1.33 +0.05 -0.11 keV absorption edge with an optical depth, tau, of 0.28 +/- 0.06. If the same model is fit to ASCA Solid-State Imaging Spectrometer spectra obtained in 1993 and 1996, then reasonable fits are also obtained, with a similar absorption feature required. The nature of this feature is highly uncertain; its energy corresponds to the K-edges of highly ionized Ne x and neutral Mg, or to an L-edge of moderately ionized Fe. Surprisingly, no strong (tau...

  6. Indirect measure of X-rays spectra using TLDs; Medicion indirecta de espectros de rayos X utilizando TLDs

    Energy Technology Data Exchange (ETDEWEB)

    Bonzi, E. V.; Mainardi, R. T. [Universidad Nacional de Cordoba, Facultad de Matematica, Astronomia y Fisica, Av. Haya de la Torre y Av. Medina Allende s/n, Ciudad Universitaria, X5016LEA Cordoba (Argentina)

    2011-10-15

    A methodology of indirect measure of X-rays spectra, emitted by conventional tubes, was developed recently and its feasibility verified in the first place by Monte Carlo simulations. For that case is intended to measure, by means of plastic scintillators, attenuation curves of dispersed beams previously. In this work were carried out measurements of attenuation curves with thermoluminescent dosimeters (TLD) to verify the kindness of the indirect measure method. The attenuation curve was also measured using an ionization chamber brand Capintec (model 192) with the purpose of making a comparison. The results of the attenuation curve measured with both dosimeters present a good resolution inside the statistical fluctuations and the spectral reconstruction using diverse parametric functions is carried out in a quick and simple way with excellent resolutions in the functional form. For this reconstruction method are of fundamental importance the following properties of the used dosimeter: in the first place the repetition of the measures, property that could check; in second place the precision of the measured data and lastly the dosimeter response, this is, the increase of the thermoluminescent signal before an increase of the photons flow of X-rays. This parameter is the gradient of the curve thermoluminescent signal versus the dose imparted to the dosimeter. The measures were realized with a generator of X-rays brand Kevex provided of a conventional tube with tungsten anti cathode that polarizes with high tension to a maximum value of 50 kV and current of 0.5 ma. (Author)

  7. Structure of dimethylphenyl betaine hydrochloride studied by X-ray diffraction, DFT calculation, NMR and FTIR spectra

    Science.gov (United States)

    Szafran, M.; Katrusiak, A.; Dega-Szafran, Z.; Kowalczyk, I.

    2013-01-01

    The structure of dimethylphenyl betaine hydrochloride (1) has been studied by X-ray diffraction, DFT calculations, NMR and FTIR spectra. The crystals are monoclinic, space group P21/c. In the crystal, the Cl- anion is connected with protonated betaine through the O-H⋯Cl- hydrogen bond of 2.943(2) Å. The structures in the gas phase (2) and water solution (3) have been optimized by the B3LYP/6-311++G(d,p) approach and the geometrical results have been compared with the X-ray data of 1. The FTIR spectrum of the solid compound is consistent with the X-ray results. The probable assignments of the anharmonic experimental vibrational frequencies of the investigated chloride (1) based on the calculated harmonic frequencies in water solution (3) are proposed. The correlations between the experimental 1H and 13C NMR chemical shifts (δexp) of 1 in D2O and the magnetic isotropic shielding constants (σcalc) calculated by the GIAO/B3LYP/6-311G++(d,p) approach, using the screening solvation model (COSMO), δexp = a + b σcalc, for optimized molecule 3 in water solution are linear and correctly reproduce the experimental chemical shifts.

  8. X-ray spectra and time variability of active galactic nuclei

    Science.gov (United States)

    Mushotzky, Richard F.; Done, Christine; Pounds, Kenneth A.

    1993-01-01

    The history and the present status of X-ray observations of AGN are outlined with reference to Seyfert Is, Seyfert IIs, and quasars. Fe K emission lines, other distortions at E greater tha 6 keV, excess emission below 2 keV, absorption, and ionized material are discussed. The continuum flux variability and line variability in Seyfert Is and the continuum variability in Seyfert IIs are examined. Models and theories of the continuum are reviewed, and the total energy budget of AGN and their similarity to Galactic black holes are also discussed.

  9. Pulsator-like Spectra from Ultraluminous X-Ray Sources and the Search for More Ultraluminous Pulsars

    Science.gov (United States)

    Pintore, F.; Zampieri, L.; Stella, L.; Wolter, A.; Mereghetti, S.; Israel, G. L.

    2017-02-01

    Ultraluminous X-ray sources (ULXs) are a population of extragalactic objects whose luminosity exceeds the Eddington limit for a 10 M ⊙ black hole (BH). Their properties have been widely interpreted in terms of accreting stellar-mass or intermediate-mass BHs. However at least three neutron stars (NSs) have been recently identified in ULXs through the discovery of periodic pulsations. Motivated by these findings we studied the spectral properties of a sample of bright ULXs using a simple continuum model which was extensively used to fit the X-ray spectra of accreting magnetic NSs in the Galaxy. We found that such a model, consisting of a power-law with a high-energy exponential cut-off, fits most of the ULX spectra analyzed here very well, at a level comparable to that of models involving an accreting BH. On these grounds alone we suggest that other non-pulsating ULXs may host NSs. We also found that above 2 keV the spectrum of known pulsating ULXs is harder than that of the majority of the other ULXs of the sample, with only IC 342 X-1 and Ho IX X-1 displaying spectra of comparable hardness. We thus suggest that these two ULXs may host an accreting NS and encourage searches for periodic pulsations in the flux.

  10. X-Ray Reflected Spectra from Accretion Disk Models. III. A Complete Grid of Ionized Reflection Calculations

    Science.gov (United States)

    García, J.; Dauser, T.; Reynolds, C. S.; Kallman, T. R.; McClintock, J. E.; Wilms, J.; Eikmann, W.

    2013-05-01

    We present a new and complete library of synthetic spectra for modeling the component of emission that is reflected from an illuminated accretion disk. The spectra were computed using an updated version of our code XILLVER that incorporates new routines and a richer atomic database. We offer in the form of a table model an extensive grid of reflection models that cover a wide range of parameters. Each individual model is characterized by the photon index Γ of the illuminating radiation, the ionization parameter ξ at the surface of the disk (i.e., the ratio of the X-ray flux to the gas density), and the iron abundance A Fe relative to the solar value. The ranges of the parameters covered are 1.2 law flux. The models are expected to provide an accurate description of the Fe K emission line, which is the crucial spectral feature used to measure black hole spin. A total of 720 reflection spectra are provided in a single FITS file (http://hea-www.cfa.harvard.edu/~javier/xillver/) suitable for the analysis of X-ray observations via the atable model in XSPEC. Detailed comparisons with previous reflection models illustrate the improvements incorporated in this version of XILLVER.

  11. HEAO 1 A-2 low-energy detector X-ray spectra of the Lupus Loop and SN 1006

    Science.gov (United States)

    Leahy, D. A.; Nousek, J.; Hamilton, A. J. S.

    1991-01-01

    The Lupus Loop and SN 1006 were observed by the A-2 low-energy detector proportional counters on the HEAO 1 satellite as part of the all-sky survey. As a result of a major advance in understanding of detector response and background accurate analysis of the data has become possible. Soft X-ray spectra for both supernova remnants were constructed from the PHA data taken during the scanning observations. Single-temperature and two-temperature Raymond-Smith models were fitted to the observed spectra. In addition, power-law and power-law plus one-temperature models were fitted to the spectrum of SN 1006. Only two-component models provide an adequate description for both Lupus Loop and SN 1006 spectra. The temperatures, column densities, and emission measures are significantly more accurate than previous results.

  12. Akn 564 an unusual component in the X-ray spectra of NLSy1 galaxies

    CERN Document Server

    Turner, T J; Netzer, H; Netzer, Hagai

    1999-01-01

    We present an ASCA observation of the NLSy1 Ark 564. The X-ray light curve shows rapid variability, but no evidence for energy-dependence to these variations, within the 0.6 -- 10 keV bandpass. A strong (EW ~ 70 eV) spectral feature is observed close to 1 keV. A similar feature has been observed in TON S180 (another NLSy1) but has not been observed in broad-line Seyfert galaxies. The feature energy suggests a large contribution from Fe L-shell lines but its intensity is difficult to explain in terms of emission and/or absorption from photoionized gas. Models based on gas in thermal equilibrium with kT ~1 keV provide an alternative parameterization of the soft spectrum. The latter may be interpreted as the hot intercloud medium, undergoing rapid cooling and producing strong Fe L-shell recombination lines. In all cases the physical conditions are rather different from those observed in broad-line Seyferts. The hard X-ray spectrum shows a broad and asymmetric Fe Kalpha line of large equivalent width (~550 eV) wh...

  13. Estimation of identification limit for a small-type OSL dosimeter on the medical images by measurement of X-ray spectra.

    Science.gov (United States)

    Takegami, Kazuki; Hayashi, Hiroaki; Okino, Hiroki; Kimoto, Natsumi; Maehata, Itsumi; Kanazawa, Yuki; Okazaki, Tohru; Hashizume, Takuya; Kobayashi, Ikuo

    2016-07-01

    Our aim in this study is to derive an identification limit on a dosimeter for not disturbing a medical image when patients wear a small-type optically stimulated luminescence (OSL) dosimeter on their bodies during X-ray diagnostic imaging. For evaluation of the detection limit based on an analysis of X-ray spectra, we propose a new quantitative identification method. We performed experiments for which we used diagnostic X-ray equipment, a soft-tissue-equivalent phantom (1-20 cm), and a CdTe X-ray spectrometer assuming one pixel of the X-ray imaging detector. Then, with the following two experimental settings, corresponding X-ray spectra were measured with 40-120 kVp and 0.5-1000 mAs at a source-to-detector distance of 100 cm: (1) X-rays penetrating a soft-tissue-equivalent phantom with the OSL dosimeter attached directly on the phantom, and (2) X-rays penetrating only the soft-tissue-equivalent phantom. Next, the energy fluence and errors in the fluence were calculated from the spectra. When the energy fluence with errors concerning these two experimental conditions was estimated to be indistinctive, we defined the condition as the OSL dosimeter not being identified on the X-ray image. Based on our analysis, we determined the identification limit of the dosimeter. We then compared our results with those for the general irradiation conditions used in clinics. We found that the OSL dosimeter could not be identified under the irradiation conditions of abdominal and chest radiography, namely, one can apply the OSL dosimeter to measurement of the exposure dose in the irradiation field of X-rays without disturbing medical images.

  14. Modelling lightcurves and spectra of transient Anomalous X-ray Pulsars

    CERN Document Server

    Zane, S; Turolla, R; Israel, G L; Nobili, L; Stella, L

    2011-01-01

    We present the first detailed joint modelling of both the timing and spectral properties during the outburst decay of transient anomalous X-ray pulsars. We consider the two sources XTE J1810-197 and CXOU J164710.2-455216, and describe the source decline in the framework of a twisted magnetosphere model, using Monte Carlo simulations of magnetospheric scattering and mimicking localized heat deposition at the NS surface following the activity. Our results support a picture in which a limited portion of the star surface close to one of the magnetic poles is heated at the outburst onset. The subsequent evolution is driven both by the cooling/varying size of the heated cap and by a progressive untwisting of the magnetosphere.

  15. Modelling lightcurves and spectra of transient Anomalous X-ray Pulsars

    Science.gov (United States)

    Zane, S.; Albano, A.; Turolla, R.; Israel, G. L.; Nobili, L.; Stella, L.

    2011-09-01

    We present the first detailed joint modelling of both the timing and spectral properties during the outburst decay of transient anomalous X-ray pulsars. We consider the two sources XTE J1810-197 and CXOU J164710.2-455216, and describe the source decline in the framework of a twisted magnetosphere model, using Monte Carlo simulations of magnetospheric scattering and mimicking localized heat deposition at the NS surface following the activity. Our results support a picture in which a limited portion of the star surface close to one of the magnetic poles is heated at the outburst onset. The subsequent evolution is driven both by the cooling/varying size of the heated cap and by a progressive untwisting of the magnetosphere.

  16. X-ray spectra of Hercules X-1. I - Iron line fluorescence from a subrelativistic shell

    Science.gov (United States)

    Pravdo, S. H.; Becker, R. H.; Boldt, E. A.; Holt, S. S.; Serlemitsos, P. J.; Swank, J. H.

    1977-01-01

    The X-ray spectrum of Her X-1 was observed in the energy range from 2 to 24 keV from August 29 to September 3, 1975. Emission features are observed near the K-alpha iron-line energy which exhibit both broadening and a double line structure. The total luminosity in these features is about 4 by 10 to the 35th power ergs/s. Iron line fluorescence from an opaque cool (not exceeding 1 million K) shell of material at the Alfven surface provides the necessary luminosity in this feature. The double line structure and the line energy width can be due to Doppler shifts if the shell is forced to corotate with the pulsar at a radius of at least 800 million cm. Implications of this model regarding physical conditions near Her X-1 are discussed.

  17. Recombination-cascade X-ray spectra of highly charged helium-like ions

    Science.gov (United States)

    Pradhan, A. K.

    1985-01-01

    It is shown that the relative intensity distribution among the X-ray spectral lines of helium-like ions from the n = 2 states produced through recombination processes such as radiative and charge transfer recombination may be given by considering in detail the radiative cascades following recombination. Model calculations are presented with predicted line ratios for Ar XVII and Fe XXV in recombination-dominated noncoronal plasmas. In particular, compared to coronal intensities, the singlet resonance line (w) should be much weaker relative to the triplet intercombination (x, y) and forbidden (z) lines, yielding large values for the ratio G = (x + y + z)/w. Accurate configuration interaction type wave functions are employed to calculate the eigenenergies, transition probabilities, and cascade coefficients. Certain relevant tokamak and astrophysical observations are discussed.

  18. Arcus: The next generation of high-resolution X-ray grating spectra

    Science.gov (United States)

    Smith, Randall

    2014-11-01

    We present the design and scientific motivation for Arcus, an X-ray grating spectrometer mission to be deployed on the International Space Station. This mission will observe structure formation at and beyond the edges of clusters and galaxies, feedback from supermassive black holes, the structure of the interstellar medium and the formation and evolution of stars. Key mission requirements will be R>2500 and >600 cm^2 of effective area at the crucial O VII and O VIII lines, with the full bandpass going from 8-52Å, with an overall minimum resolution of 1300 and effective area >150 cm^2. We will use the silicon pore optics proposed for ESA's Athena mission, paired with off-plane gratings being developed at the University of Iowa and combined with MIT/Lincoln Labs CCDs.

  19. Accuracy of Mass and Radius Determination for Neutron Stars in X-ray Bursters from Simulated LOFT Spectra

    Science.gov (United States)

    Majczyna, A.; Madej, J.; Różańska, A.; Należyty, M.

    2017-06-01

    We present a simulation of an X-ray spectrum of a hot neutron star, as would be seen by the LAD detector on board of LOFT satellite. We also compute a grid of theoretical spectra corresponding to a range of effective temperatures Teff and surface gravities log g with values corresponding to compact stars in Type I X-ray bursters. A neutron star with the mass M=1.64 M⊙ and the radius R=11.95 km (which yields the surface gravity log g=14.30 [cgs] and the surface redshift z=0.30) is used in simulation. Accuracy of mass and radius determination by fitting theoretical spectra to the observed one is found to be M=1.64+0.16-0.02 M⊙ and R=11.95+1.57-0.40 km (2σ). The confidence contours for these two variables are narrow but elongated, and therefore the resulting constraints on the EOS cannot be strong. Note, that in this paper we aim to discuss error contours of NS mass and radius, whereas discussion of EOS is beyond the scope of this work.

  20. Bayesian inference of x-ray diffraction spectra from warm dense matter with the one-component-plasma model

    Science.gov (United States)

    Clérouin, Jean; Desbiens, Nicolas; Dubois, Vincent; Arnault, Philippe

    2016-12-01

    We show that the Bayesian inference of recently measured x-ray diffraction spectra from laser-shocked aluminum [L. B. Fletcher et al., Nat. Photon. 9, 274 (2015), 10.1038/nphoton.2015.41] with the one-component-plasma (OCP) model performs remarkably well at estimating the ionic density and temperature. This statistical approach requires many evaluations of the OCP static structure factor, which were done using a recently derived analytic fit. The atomic form factor is approximated by an exponential function in the diffraction window of the first peak. The electronic temperature is then estimated from a comparison of this approximated form factor with the electronic structure of an average atom model. Out-of-equilibrium states, with electrons hotter than ions, are diagnosed for the spectra obtained early after the pump, whereas at a late time delay the plasma is at thermal equilibrium. Apart from the present findings, this OCP-based modeling of warm dense matter has an important role to play in the interpretation of x-ray Thomson scattering measurements currently performed at large laser facilities.

  1. Merging Structural Information from X-ray Crystallography, Quantum Chemistry, and EXAFS Spectra: The Oxygen-Evolving Complex in PSII.

    Science.gov (United States)

    Chernev, Petko; Zaharieva, Ivelina; Rossini, Emanuele; Galstyan, Artur; Dau, Holger; Knapp, Ernst-Walter

    2016-10-12

    Structural data of the oxygen-evolving complex (OEC) in photosystem II (PSII) determined by X-ray crystallography, quantum chemistry (QC), and extended X-ray absorption fine structure (EXAFS) analyses are presently inconsistent. Therefore, a detailed study of what information can be gained about the OEC through a comparison of QC and crystallographic structure information combined with the information from range-extended EXAFS spectra was undertaken. An analysis for determining the precision of the atomic coordinates of the OEC by QC is carried out. OEC model structures based on crystallographic data that are obtained by QC from different research groups are compared with one another and with structures obtained by high-resolution crystallography. The theory of EXAFS spectra is summarized, and the application of EXAFS spectra to the experimental determination of the structure of the OEC is detailed. We discriminate three types of parameters entering the formula for the EXAFS spectrum: (1) model-independent, predefined, and fixed; (2) model-dependent that can be computed or adjusted; and (3) model-dependent that must be adjusted. The information content of EXAFS spectra is estimated and is related to the precision of atomic coordinates and resolution power to discriminate different atom-pair distances of the OEC. It is demonstrated how a precise adjustment of atomic coordinates can yield a nearly perfect representation of the experimental OEC EXAFS spectrum, but at the expense of overfitting and losing the knowledge of the initial OEC model structure. Introducing a novel type of penalty function, it is shown that moderate adjustment of atomic coordinates to the EXAFS spectrum limited by constraints avoids overfitting and can be used to validate different OEC model structures. This technique is used to identify the OEC model structures whose computed OEC EXAFS spectra agree best with the measured spectrum. In this way, the most likely S-state and protonation pattern

  2. X-ray Energy Spectra of the Super-soft X-ray Sources CAL87 and RXJ0925.7-4758 Observed with ASCA

    CERN Document Server

    Ebisawa, K; Kotani, T; Asai, K; Dotani, T; Nagase, F; Hartmann, H W; Heise, J; Kahabka, P; Van Teeseling, A

    2000-01-01

    We report observation results of the super-soft X-ray sources (SSS) CAL87 and RXJ0925.7-4758 with the X-ray CCD cameras (Solid-state Imaging Spectrometer; SIS) on-board the ASCA satellite. We have applied theoretical spectral models to CAL87, and constrained the white dwarf mass and intrinsic luminosity as 0.8 - 1.2 M_solar and 4 x 10^{37}- 1.2 x 10^{38} erg s^{-1}, respectively. However, we have found the observed luminosity is an order of magnitude smaller than the theoretical estimate, which indicates the white dwarf is permanently blocked by the accretion disk, and we are observing a scattering emission by a fully ionized accretion disk corona (ADC) whose column density is ~ 1.5 x 10^{23} cm^{-2}. Through simulation, we have shown that the orbital eclipse can be explained by the ADC model, such that a part of the extended X-ray emission from the ADC is blocked by the companion star filling its Roche lobe. We have found that very high surface gravity and temperature, ~ 10^{10} cm s^{-2} and ~ 100 eV respec...

  3. Role of quantum nuclei and local fields in the x-ray absorption spectra of water and ice

    CERN Document Server

    Kong, Lingzhu; Car, Roberto

    2012-01-01

    We calculate the x-ray absorption spectra of liquid water at ambient conditions and of hexagonal ice close to melting, using a static GW approach that includes approximately local field effects. Quantum dynamics of the nuclei is taken into account by averaging the absorption cross section over molecular configurations generated by path integral simulations. We find that inclusion of quantum disorder is essential to bring the calculated spectra in close agreement with experiment. In particular, the intensity of the pre-edge feature, a spectral signature of broken and distorted hydrogen bonds, is accurately reproduced, in water and ice, only when quantum nuclei are considered. The effect of the local fields is less important but non negligible, particularly in ice.

  4. The Effect of Broadband Soft X-Rays in SO2-Containing Ices: Implications on the Photochemistry of Ices toward Young Stellar Objects

    Science.gov (United States)

    Pilling, S.; Bergantini, A.

    2015-10-01

    We investigate the effects produced mainly by broadband soft X-rays up to 2 keV (plus fast (˜keV) photoelectrons and low-energy (˜eV) induced secondary electrons) in the ice mixtures containing H2O:CO2:NH3:SO2 (10:1:1:1) at two different temperatures (50 and 90 K). The experiments are an attempt to simulate the photochemical processes induced by energetic photons in SO2-containing ices present in cold environments in the ices surrounding young stellar objects (YSO) and in molecular clouds in the vicinity of star-forming regions, which are largely illuminated by soft X-rays. The measurements were performed using a high-vacuum portable chamber from the Laboratório de Astroquímica e Astrobiologia (LASA/UNIVAP) coupled to the spherical grating monochromator beamline at the Brazilian Synchrotron Light Source (LNLS) in Campinas, Brazil. In situ analyses were performed by a Fourier transform infrared spectrometer. Sample processing revealed the formation of several organic molecules, including nitriles, acids, and other compounds such as H2O2, H3O+, SO3, CO, and OCN-. The dissociation cross section of parental species was on the order of (2-7) × 10-18 cm2. The ice temperature does not seem to affect the stability of SO2 in the presence of X-rays. Formation cross sections of new species produced were also determined. Molecular half-lives at ices toward YSOs due to the presence of incoming soft X-rays were estimated. The low values obtained employing two different models of the radiation field of YSOs (TW Hydra and typical T-Tauri star) reinforce that soft X-rays are indeed a very efficient source of molecular dissociation in such environments.

  5. Specdata: Automated Analysis Software for Broadband Spectra

    Science.gov (United States)

    Oliveira, Jasmine N.; Martin-Drumel, Marie-Aline; McCarthy, Michael C.

    2017-06-01

    With the advancement of chirped-pulse techniques, broadband rotational spectra with a few tens to several hundred GHz of spectral coverage are now routinely recorded. When studying multi-component mixtures that might result, for example, with the use of an electrical discharge, lines of new chemical species are often obscured by those of known compounds, and analysis can be laborious. To address this issue, we have developed SPECdata, an open source, interactive tool which is designed to simplify and greatly accelerate the spectral analysis and discovery. Our software tool combines both automated and manual components that free the user from computation, while giving him/her considerable flexibility to assign, manipulate, interpret and export their analysis. The automated - and key - component of the new software is a database query system that rapidly assigns transitions of known species in an experimental spectrum. For each experiment, the software identifies spectral features, and subsequently assigns them to known molecules within an in-house database (Pickett .cat files, list of frequencies...), or those catalogued in Splatalogue (using automatic on-line queries). With suggested assignments, the control is then handed over to the user who can choose to accept, decline or add additional species. Data visualization, statistical information, and interactive widgets assist the user in making decisions about their data. SPECdata has several other useful features intended to improve the user experience. Exporting a full report of the analysis, or a peak file in which assigned lines are removed are among several options. A user may also save their progress to continue at another time. Additional features of SPECdata help the user to maintain and expand their database for future use. A user-friendly interface allows one to search, upload, edit or update catalog or experiment entries.

  6. X-ray luminescence spectra of graded-gap Al xGa 1- xAs structures irradiated by alpha particle

    Science.gov (United States)

    Šilėnas, A.; Požela, J.; Požela, K.; Jucienė, V.; Dapkus, L.

    2011-12-01

    The influence of 241Am alpha particle irradiation on X-ray luminescence spectra of the graded-gap AlxGa1-xAs structures of different thicknesses is investigated. It is observed that the integral X-ray luminescence intensity of nonirradiated thin (15 μm) structure is 1.4 times less than that in the thick (32 μm) structure, and this difference increases to 3 times after 3×1010 cm-2 dose of irradiation by alpha particle. The X-ray luminescence intensity of the energy hνFgg is responsible of that large difference, because it shifts the X-ray generated carriers to the narrow-gap surface with great nonradiative surface recombination rate. The alpha particle irradiation increases nonradiative recombination rate and causes a decrease of the X-ray luminescence intensity of all spectra lines in the thin (15 μm) detector. The most significant drop in X-ray luminescence efficiency is observed from the region at narrow-gap surface after the initial stage (109 cm-2 dose) of alpha particle irradiation. In the 32 μm thick detector, the luminescence intensity of the energy hν=1.8 eV does not change up to 2×1010 cm-2 of alpha particle irradiation dose. That means the high irradiation hardness of the thick graded-gap X-ray detector with optical response.

  7. THE CHANDRA MULTI-WAVELENGTH PROJECT: OPTICAL SPECTROSCOPY AND THE BROADBAND SPECTRAL ENERGY DISTRIBUTIONS OF X-RAY-SELECTED AGNs

    Energy Technology Data Exchange (ETDEWEB)

    Trichas, Markos; Green, Paul J.; Aldcroft, Tom; Kim, Dong-Woo; Mossman, Amy [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Silverman, John D. [Institute for the Physics and Mathematics of the Universe (IPMU), University of Tokyo, Kashiwanoha 5-1-5, Kashiwa-shi, Chiba 277-8568 (Japan); Barkhouse, Wayne [Department of Physics and Astrophysics, University of North Dakota, Grand Forks, ND 58202 (United States); Cameron, Robert A. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Constantin, Anca [Department of Physics and Astronomy, James Madison University, PHCH, Harrisonburg, VA 22807 (United States); Ellison, Sara L. [Department of Physics and Astronomy, University of Victoria, Victoria, BC V8P 1A1 (Canada); Foltz, Craig [Division of Astronomical Sciences, National Science Foundation, 4201 Wilson Blvd., Arlington, VA 22230 (United States); Haggard, Daryl [Center for Interdisciplinary Exploration and Research in Astrophysics, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Jannuzi, Buell T. [NOAO, Kitt Peak National Observatory, Tucson, AZ 85726 (United States); Marshall, Herman L. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 (United States); Perez, Laura M. [Department of Astronomy, California Institute of Technology, 1200 East California Blvd, Pasadena, CA 91125 (United States); Romero-Colmenero, Encarni [South African Astronomical Observatory, P.O. Box 9, Observatory, 7935 (South Africa); Ruiz, Angel [Osservatorio Astronomico di Brera-INAF, Milan (Italy); Smith, Malcolm G., E-mail: mtrichas@cfa.harvard.edu [Cerro Tololo Interamerican Observatory, La Serena (Chile); and others

    2012-06-01

    From optical spectroscopy of X-ray sources observed as part of the Chandra Multi-wavelength Project (ChaMP), we present redshifts and classifications for a total of 1569 Chandra sources from our targeted spectroscopic follow-up using the FLWO/1.5 m, SAAO/1.9 m, WIYN 3.5 m, CTIO/4 m, KPNO/4 m, Magellan/6.5 m, MMT/6.5 m, and Gemini/8 m telescopes, and from archival Sloan Digital Sky Survey (SDSS) spectroscopy. We classify the optical counterparts as 50% broad-line active galactic nuclei (AGNs), 16% emission line galaxies, 14% absorption line galaxies, and 20% stars. We detect QSOs out to z {approx} 5.5 and galaxies out to z {approx} 3. We have compiled extensive photometry, including X-ray (ChaMP), ultraviolet (GALEX), optical (SDSS and ChaMP-NOAO/MOSAIC follow-up), near-infrared (UKIDSS, Two Micron All Sky Survey, and ChaMP-CTIO/ISPI follow-up), mid-infrared (WISE), and radio (FIRST and NVSS) bands. Together with our spectroscopic information, this enables us to derive detailed spectral energy distributions (SEDs) for our extragalactic sources. We fit a variety of template SEDs to determine bolometric luminosities, and to constrain AGNs and starburst components where both are present. While {approx}58% of X-ray Seyferts (10{sup 42} erg s{sup -1} < L{sub 2-10keV} <10{sup 44} erg s{sup -1}) require a starburst event (>5% starburst contribution to bolometric luminosity) to fit observed photometry only 26% of the X-ray QSO (L{sub 2-10keV} >10{sup 44} erg s{sup -1}) population appear to have some kind of star formation contribution. This is significantly lower than for the Seyferts, especially if we take into account torus contamination at z > 1 where the majority of our X-ray QSOs lie. In addition, we observe a rapid drop of the percentage of starburst contribution as X-ray luminosity increases. This is consistent with the quenching of star formation by powerful QSOs, as predicted by the merger model, or with a time lag between the peak of star formation and QSO

  8. Local moments and electronic correlations in Fe-based Heusler alloys: Kα x-ray emission spectra measurements

    Energy Technology Data Exchange (ETDEWEB)

    Svyazhin, Artem, E-mail: svyazhin@imp.uran.ru [M.N. Mikheev Institute of Metal Physics, Russian Academy of Sciences – Ural Division, 620990 Yekaterinburg (Russian Federation); Kurmaev, Ernst; Shreder, Elena; Shamin, Sergey [M.N. Mikheev Institute of Metal Physics, Russian Academy of Sciences – Ural Division, 620990 Yekaterinburg (Russian Federation); Sahle, Christoph J. [ESRF – The European Synchrotron, CS40220, 38043 Grenoble Cedex 9 (France)

    2016-09-15

    Heusler alloys are a property-rich class of materials, intensively investigated today from both theoretical and real-world application points of view. In this paper, we attempt to shed light on the role of electronic correlations in the Fe{sub 2}MeAl group (where Me represents all 3d elements from Ti to Ni) of Heusler alloys. For this purpose, we have investigated the local moments of iron by means of the x-ray emission spectroscopy technique. To obtain numerical values of local moments, the Kα-FWHM method has been employed for the first time. In every compound of the group, the presence of a local moment on the Fe atom was detected. As has been revealed, the values of these moments are temperature-independent, pointing to an insufficiency of a pure itinerant approach to magnetism in these alloys. We also comprehensively compare the usage of Kβ main lines and Kα spectra as tools for the probing of local moments and point out the significant advantages of the latter. - Highlights: • Local spin moments of iron in Fe{sub 2}MeAl (Me = Ti … Ni) Heusler alloys were investigated by means of x-ray emission spectroscopy. • Independence of the local moments from temperature confirms their localized nature. • A local moment value of iron in Fe{sub 2}MeAl raises with the atomic number of element Me. • The applicability of the Kα x-ray emission line for extracting local moment values of 3d elements was established.

  9. 1SXPS: A Deep Swift X-Ray Telescope Point Source Catalog with Light Curves and Spectra

    Science.gov (United States)

    Evans, P. A.; Osborne, J. P.; Beardmore, A. P.; Page, K. L.; Willingale, R.; Mountford, C. J.; Pagani, C.; Burrows, D. N.; Kennea, J. A.; Perri, M.; Tagliaferri, G.; Gehrels, N.

    2013-01-01

    We present the 1SXPS (Swift-XRT point source) catalog of 151,524 X-ray point sources detected by the Swift-XRT in 8 yr of operation. The catalog covers 1905 sq deg distributed approximately uniformly on the sky. We analyze the data in two ways. First we consider all observations individually, for which we have a typical sensitivity of approximately 3 × 10(exp -13) erg cm(exp -2) s(exp -1) (0.3-10 keV). Then we co-add all data covering the same location on the sky: these images have a typical sensitivity of approximately 9 × 10(exp -14) erg cm(exp -2) s(exp -1) (0.3-10 keV). Our sky coverage is nearly 2.5 times that of 3XMM-DR4, although the catalog is a factor of approximately 1.5 less sensitive. The median position error is 5.5 (90% confidence), including systematics. Our source detection method improves on that used in previous X-ray Telescope (XRT) catalogs and we report greater than 68,000 new X-ray sources. The goals and observing strategy of the Swift satellite allow us to probe source variability on multiple timescales, and we find approximately 30,000 variable objects in our catalog. For every source we give positions, fluxes, time series (in four energy bands and two hardness ratios), estimates of the spectral properties, spectra and spectral fits for the brightest sources, and variability probabilities in multiple energy bands and timescales.

  10. Correlations Between Variations in Solar EUV and Soft X-Ray Irradiance and Photoelectron Energy Spectra Observed on Mars and Earth

    Science.gov (United States)

    Peterson, W. K.; Brain, D. A.; Mitchell, D. L.; Bailey, S. M.; Chamberlin, P. C.

    2013-01-01

    Solar extreme ultraviolet (EUV; 10-120 nm) and soft X-ray (XUV; 0-10 nm) radiation are major heat sources for the Mars thermosphere as well as the primary source of ionization that creates the ionosphere. In investigations of Mars thermospheric chemistry and dynamics, solar irradiance models are used to account for variations in this radiation. Because of limited proxies, irradiance models do a poor job of tracking the significant variations in irradiance intensity in the EUV and XUV ranges over solar rotation time scales when the Mars-Sun-Earth angle is large. Recent results from Earth observations show that variations in photoelectron energy spectra are useful monitors of EUV and XUV irradiance variability. Here we investigate photoelectron energy spectra observed by the Mars Global Surveyor (MGS) Electron Reflectometer (ER) and the FAST satellite during the interval in 2005 when Earth, Mars, and the Sun were aligned. The Earth photoelectron data in selected bands correlate well with calculations based on 1 nm resolution observations above 27 nm supplemented by broadband observations and a solar model in the 0-27 nm range. At Mars, we find that instrumental and orbital limitations to the identifications of photoelectron energy spectra in MGS/ER data preclude their use as a monitor of solar EUV and XUV variability. However, observations with higher temporal and energy resolution obtained at lower altitudes on Mars might allow the separation of the solar wind and ionospheric components of electron energy spectra so that they could be used as reliable monitors of variations in solar EUV and XUV irradiance than the time shifted, Earth-based, F(10.7) index currently used.

  11. Spatially Resolved Spectra from a new X-ray Imaging Crystal Spectrometer for Measurements of Ion and Electron Temperature Profiles

    Energy Technology Data Exchange (ETDEWEB)

    Bitter, M; Stratton, B; Roquemore, A; Mastrovito, D; Lee, S; Bak, J; Moon, M; Nam, U; Smith, G; Rice, J; Beiersdorfer, P; Fraenkel, B

    2004-08-10

    A new type of high-resolution X-ray imaging crystal spectrometer is being developed to measure ion and electron temperature profiles in tokamak plasmas. The instrument is particularly valuable for diagnosing plasmas with purely Ohmic heating and rf heating, since it does not require the injection of a neutral beam - although it can also be used for the diagnosis of neutral-beam heated plasmas. The spectrometer consists of a spherically bent quartz crystal and a two-dimensional position-sensitive detector. It records spectra of helium-like argon (or krypton) from multiple sightlines through the plasma and projects a de-magnified image of a large plasma cross-section onto the detector. The spatial resolution in the plasma is solely determined by the height of the crystal, its radius of curvature, and the Bragg angle. This new X-ray imaging crystal spectrometer may also be of interest for the diagnosis of ion temperature profiles in future large tokamaks, such as KSTAR and ITER, where the application of the presently used charge-exchange spectroscopy will be difficult, if the neutral beams do not penetrate to the plasma center. The paper presents the results from proof-of-principle experiments performed with a prototype instrument at Alcator C-Mod.

  12. Soft x-ray spectra and collisional ionization equilibrium of iron ions with data upgrade of electron-ion collisions

    Science.gov (United States)

    Liang, G. Y.; Wei, H. G.; Zhao, G.; Zhong, J. Y.

    2016-06-01

    Line emissivities and ionic fraction in (non-)equilibrium are crucial for understanding the x-ray and extreme ultraviolet (EUV) spectra. These emission originate from electron-impact excitations for a level population of highly charged ions in coronal-like plasma. Recently, a large amount of excitation data was generated within the R-matrix framework by the computational atomic physics community, especially the UK APAP network. These data take resonances in electron-ion collisions into account appropriately, which enhances the effective excitation rates and also the line emissivities in x-ray and EUV regions. For ionization equilibrium data, the earlier compilation by Mazzotta et al (1998 Astron. Astrophys. Supp. Ser. 133 403) was used extensively by the astronomical community until the update by Bryans et al (2006 Astrophys. J. Supp. Ser. 167 343), as well as the compilation of Dere (2007 Astron. Astrophys. 466 771) for electron-impact ionization rates. In past years, many experimental measurements have been performed of highly charged iron ions in heavy-ion storage ring facilities. In this work, we will investigate the line emissivities and ionization equilibrium of highly charged iron ions by using recent theoretical or experimental data of electron-impact excitations and ionizations.

  13. Detection of the X-ray spectra of imploding neon Z-pinch with elliptically bent mica crystal spectrometer

    Institute of Scientific and Technical Information of China (English)

    Jun Shi; Shali Xiao; Hongjian Wang; Xianbin Huang; Libing Yang; Shenye Liu

    2008-01-01

    A wide variety of X-ray and extreme ultraviolet diagnostics are being developed to study on Yang acceler- ator. An elliptically bent crystal spectrometer is designed with a focal length of 1350 mm. A mica crystal with an interplanar spacing of 1.984 nm bent onto an elliptical substrate with eccentricity of 0.9485 is used. The crystal analyzer covers the Bragg angle range from 30° to 60°. The mica crystal can efficiently reflect radiation in multiple orders, covering the entire spectral range from 0.1 to 1.73 nm except for a gap from 0.86 to 1.0 nm. The application experiment is performed on Yang accelerator using the bent mica crystal analyzer. Spectra of neon-puff Z-pinch plasmas are recorded with a X-ray film, showing the H-like and the He-like lines of neon. Each spectrum has been identified and used for the wavelength calibration, and most of the line radiation is contained in the He-α and the L-α lines. The experimental results have demonstrated that the spectral resolution approximates 379.

  14. A detailed analysis of the high-resolution X-ray spectra of NGC 3516: variability of the ionized absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Huerta, E. M.; Krongold, Y.; Jimenez-Bailon, E. [Departamento de Astronomia Extragalactica y Cosmologia, Instituto de Astronomia, Universidad Nacional Autonoma de Mexico (UNAM), Apartado Postal 70-264, 04510 Mexico D.F. (Mexico); Nicastro, F. [Osservatorio Astronomico di Roma-INAF, Via di Frascati 33, I-00040 Monte Porzio Catone, RM (Italy); Mathur, S. [Astronomy Department, The Ohio State University, Enarson Hall, 140 West 18th Avenue, Columbus, OH 43210 (United States); Longinotti, A. L. [European Space Astronomy Centre of ESA, E-28691, Madrid (Spain)

    2014-09-20

    The 1.5 Seyfert galaxy NGC 3516 presents a strong time variability in X-rays. We re-analyzed the nine observations performed in 2006 October by XMM-Newton and Chandra in the 0.3 to 10 keV energy band. An acceptable model was found for the XMM-Newton data fitting the EPIC-PN and RGS spectra simultaneously; later, this model was successfully applied to the contemporary Chandra high-resolution data. The model consists of a continuum emission component (power law + blackbody) absorbed by four ionized components (warm absorbers), and 10 narrow emission lines. Three absorbing components are warm, producing features only in the soft X-ray band. The fourth ionization component produces Fe XXV and Fe XXVI in the hard-energy band. We study the time response of the absorbing components to the well-detected changes in the X-ray luminosity of this source and find that the two components with the lower ionization state show clear opacity changes consistent with gas close to photoionization equilibrium. These changes are supported by the models and by differences in the spectral features among the nine observations. On the other hand, the two components with higher ionization state do not seem to respond to continuum variations. The response time of the ionized absorbers allows us to constrain their electron density and location. We find that one component (with intermediate ionization) must be located within the obscuring torus at a distance 2.7 × 10{sup 17} cm from the central engine. This outflowing component likely originated in the accretion disk. The three remaining components are at distances larger than 10{sup 16}-10{sup 17} cm. Two of the absorbing components in the soft X-rays have similar outflow velocities and locations. These components may be in pressure equilibrium, forming a multi-phase medium, if the gas has metallicity larger than the solar one (≳ 5 Z {sub ☉}). We also search for variations in the covering factor of the ionized absorbers (although partial

  15. Strong Role of Non-stationary Accretion in Spectral Transitions of X-ray Binaries and Implications for Revealing the Accretion Geometry and Broadband Radiation Mechanisms

    Science.gov (United States)

    Yu, Wenfei; Yan, Zhen; Tang, Jing; Wu, Yuxiang

    Observations of spectral transitions from the hard state to the soft state in bright X-ray binaries show strong evidence that the rate-of-change of the mass accretion rate plays a dominant role in determining the luminosity at which the spectral transition occurs. This indicates that in many cases, especially accretion in transients during outbursts, the rate-of-change of the mass accretion rate is the primary parameter driving high energy phenomena. Although this goes beyond the scope of current stationary model of disk and jet, it tells us that it is the rate-of-change of the mass accretion rate that we need to trace observationally. Since state transition is a broadband phenomenon, multi-wavelength observations of spectral transitions of different rate-of-changes of mass accretion rate are expect to reveal the accretion geometry and broadband radiation mechanisms.

  16. On the Weak-Wind Problem in Massive Stars: X-Ray Spectra Reveal a Massive Hot Wind in mu Columbae

    Science.gov (United States)

    Huenemoerder, David P.; Oskinova, Lidia M.; Ignace, Richard; Waldron, Wayne L.; Todt, Helge; Hamaguchi, Kenji; Kitamoto, Shunji

    2012-01-01

    Mu Columbae is a prototypical weak-wind O star for which we have obtained a high-resolution X-ray spectrum with the Chandra LETG/ACIS instrument and a low-resolution spectrum with Suzaku. This allows us, for the first time, to investigate the role of X-rays on the wind structure in a bona fide weak-wind system and to determine whether there actually is a massive hot wind. The X-ray emission measure indicates that the outflow is an order of magnitude greater than that derived from UV lines and is commensurate with the nominal wind-luminosity relationship for O stars. Therefore, the "weak-wind problem"--identified from cool wind UV/optical spectra--is largely resolved by accounting for the hot wind seen in X-rays. From X-ray line profiles, Doppler shifts, and relative strengths, we find that this weak-wind star is typical of other late O dwarfs. The X-ray spectra do not suggest a magnetically confined plasma-the spectrum is soft and lines are broadened; Suzaku spectra confirm the lack of emission above 2 keV. Nor do the relative line shifts and widths suggest any wind decoupling by ions. The He-like triplets indicate that the bulk of the X-ray emission is formed rather close to the star, within five stellar radii. Our results challenge the idea that some OB stars are "weak-wind" stars that deviate from the standard wind-luminosity relationship. The wind is not weak, but it is hot and its bulk is only detectable in X-rays.

  17. Application of an expectation maximization method to the reconstruction of X-ray-tube spectra from transmission data

    Science.gov (United States)

    Endrizzi, M.; Delogu, P.; Oliva, P.

    2014-12-01

    An expectation maximization method is applied to the reconstruction of X-ray tube spectra from transmission measurements in the energy range 7-40 keV. A semiconductor single-photon counting detector, ionization chambers and a scintillator-based detector are used for the experimental measurement of the transmission. The number of iterations required to reach an approximate solution is estimated on the basis of the measurement error, according to the discrepancy principle. The effectiveness of the stopping rule is studied on simulated data and validated with experiments. The quality of the reconstruction depends on the information available on the source itself and the possibility to add this knowledge to the solution process is investigated. The method can produce good approximations provided that the amount of noise in the data can be estimated.

  18. Soft-X-ray spectra of highly charged Os, Bi, Th, and U ions in an electron beam ion trap

    Energy Technology Data Exchange (ETDEWEB)

    Trabert, E; Beiersdorfer, P; Fournier, K B; Chen, M H

    2004-12-03

    Systematic variation of the electron-beam energy in an electron-beam ion trap has been employed to produce soft-X-ray spectra of Os, Bi, Th, and U with highest charge states ranging up to Ni-like ions. Guided by relativistic atomic structure calculations, the strongest lines have been identified with {Delta}n = 0 (n = 4 to n' = 4) transitions in Rb- to Cu-like ions. The rather weak 4p-4d transitions are much less affected by QED contributions than the dominant 4s-4p transitions. Our wavelength measurements consequently provide benchmarks with and (almost) without QED. Because the radiative corrections are not very sensitive to the number of electrons in the valence shell, our data, moreover, provide benchmarks for the evaluation of electron-electron interactions.

  19. Theoretical characterization of X-ray absorption, emission, and photoelectron spectra of nitrogen doped along graphene edges.

    Science.gov (United States)

    Wang, Xianlong; Hou, Zhufeng; Ikeda, Takashi; Oshima, Masaharu; Kakimoto, Masa-aki; Terakura, Kiyoyuki

    2013-01-24

    K-edge X-ray absorption (XAS), emission (XES), and photoelectron (XPS) spectra of nitrogen doped along graphene edges are systematically investigated by using first-principles methods. In this study we considered pyridinium-like, pyridine-like, cyanide-like, and amine-like nitrogens at armchair and zigzag edges and pyrrole-like nitrogen at armchair edge as well as graphite-like nitrogen at graphene interior site. Our results indicate that nitrogen configuration and its location (armchair or zigzag edge) in nitrogen-doped graphene can be identified via the spectral analysis. Furthermore, some controversial spectral features observed in experiment for N-doped graphene-like materials are unambiguously assigned. The present analysis gives an explanation to the reason why the peak assignment is usually made differently between XPS and XAS.

  20. The x-ray emission spectra of multicharged xenon ions in a gas puff laser-produced plasma

    Energy Technology Data Exchange (ETDEWEB)

    Skobelev, I.Yu.; Dyakin, V.M.; Faenov, A.Ya. [Multicharged Ion Spectra Data Center, VNIIFTRI, Mendeleevo (Russian Federation); Bartnik, A.; Fiedorowicz, H.; Jarocki, R.; Kostecki, J.; Szczurek, M. [Institute of Optoelectronics, Military University of Technology, Warsaw (Poland); Biemont, E. [Institut de Physique Nucleaire Experimentale, Universite de Liege, Liege (Belgium); Astrophysique et Spectroscopie, Universite de Mons-Hainaut, Mons (Belgium); Quinet, P. [Astrophysique et Spectroscopie, Universite de Mons-Hainaut, Mons (Belgium); Nilsen, J. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Behar, E.; Doron, R.; Mandelbaum, P.; Schwob, J.L. [Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem (Israel)

    1999-01-14

    Emission spectra of multicharged xenon ions produced by a laser gas puff are observed with high spectral resolution in the 8.5-9.5 and 17-19 A wavelength ranges. Three different theoretical methods are employed to obtain 3l-n'l'(n' = 4 to 10) wavelengths and Einstein coefficients for Ni-like Xe{sup 26+}. For the 3d-4p transitions, very good agreement is found between the experimental wavelengths and the various theoretical wavelengths. These accurate energy level measurements can be useful for studying the Ni-like xenon x-ray laser scheme. On the other hand, several intense spectral lines could not be identified as 3l-n'l' lines of Ni-like xenon, despite the very good agreement between the wavelengths and Einstein coefficients calculated for these transitions using the three different methods. (author)

  1. Insoluble Content, Ionic Composition, Density, and X-Ray Diffraction Spectra of 6 Evaporites from Niger Republic

    Directory of Open Access Journals (Sweden)

    Hassidou Saidou

    2015-01-01

    Full Text Available Some physicochemical (insoluble content, ionic composition, density, and X-ray diffraction spectra characteristics of Nigerien evaporites were investigated in this study. The results obtained showed that trona is the main mineral contained in Agadez, Dirkou, Niamey, and Zinder evaporites while thenardite and halite constitute the major minerals in Bilma and Tabalak evaporites, respectively. In addition, all evaporites samples investigated revealed the presence of quartz and halite. Other interesting minerals (calcite, gypsum, sylvite, aphthitalite, nahcolite, illite, burkeite, kaolinite, griceite, and talc were also detected. The use of Agadez, Dirkou, Niamey, and Zinder evaporites as catalyst to accelerate cowpea cooking is due to bicarbonates ions present in trona. Bilma and Tabalak evaporites employed in animal feeding are due to the halite contained in a significant quantity.

  2. The MUSCLES Treasury Survey III: X-ray to Infrared Spectra of 11 M and K Stars Hosting Planets

    CERN Document Server

    Loyd, R O Parke; Youngblood, Allison; Schneider, Christian; Brown, Alexander; Hu, Renyu; Linsky, Jeffrey; Froning, Cynthia S; Redfield, Seth; Rugheimer, Sarah; Tian, Feng

    2016-01-01

    We present a catalog of panchromatic spectral energy distributions (SEDs) for 7 M and 4 K dwarf stars that span X-ray to infrared wavelengths (5 {\\AA} - 5.5 {\\mu}m). These SEDs are composites of Chandra or XMM-Newton data from 5 - ~50 {\\AA}, a plasma emission model from ~50 - 100 {\\AA}, broadband empirical estimates from 100 - 1170 {\\AA}, HST data from 1170 - 5700 {\\AA}, including a reconstruction of stellar Ly{\\alpha} emission at 1215.67 {\\AA}, and a PHOENIX model spectrum from 5700 - 55000 {\\AA}. Using these SEDs, we computed the photodissociation rates of several molecules prevalent in planetary atmospheres when exposed to each star's unattenuated flux ("unshielded" photodissociation rates) and found that rates differ among stars by over an order of magnitude for most molecules. In general, the same spectral regions drive unshielded photodissociations both for the minimally and maximally FUV active stars. However, for ozone visible flux drives dissociation for the M stars whereas NUV flux drives dissociati...

  3. X-ray characterization by energy-resolved powder diffraction

    Directory of Open Access Journals (Sweden)

    G. Cheung

    2016-08-01

    Full Text Available A method for single-shot, nondestructive characterization of broadband x-ray beams, based on energy-resolved powder diffraction, is described. Monte-Carlo simulations are used to simulate data for x-ray beams in the keV range with parameters similar to those generated by betatron oscillations in a laser-driven plasma accelerator. The retrieved x-ray spectra are found to be in excellent agreement with those of the input beams for realistic numbers of incident photons. It is demonstrated that the angular divergence of the x rays can be deduced from the deviation of the detected photons from the Debye-Scherrer rings which would be produced by a parallel beam. It is shown that the angular divergence can be measured as a function of the photon energy, yielding the angularly resolved spectrum of the input x-ray beam.

  4. The 5 Hour Pulse Period and Broadband Spectrum of the Symbiotic X-Ray Binary 3A 1954+319

    Science.gov (United States)

    Marcu, Diana M.; Fuerst, Felix; Pottschmidt, Katja; Grinberg, Victoria; Miller, Sebstian; Wilms, Joern; Postnov, Konstantin A.; Corbet, Robin H. D.; Markwardt, Craig B.; Cadolle Bel, Marion

    2011-01-01

    We present an analysis of the highly variable accreting X-ray pulsar 3A 1954+319 using 2005-2009 monitoring data obtained with INTEGRAL and Swift. This considerably extends the pulse period history and covers flaring episodes in 2005 and 2008. In 2006 the source was identified as one of only a few known symbiotic X-ray binaries, Le" systems composed of a neutron star accreting from the inhomogeneous medium around an M-giant star. The extremely long pulse period of approximately 5.3 h is directly visible in the 2008 INTEGRAL-ISGRI outburst light curve. The pulse profile is double peaked and not significantly energy dependent. During the outburst a strong spin-up of -1.8 x 10(exp -4) h h(exp -1) occurred. Between 2005 and 2008 a long term spin-down trend of 2.1 x 10(exp -5) h h(exp -1) was observed for the first time for this source. The 3-80 keV pulse peak spectrum of 3A 1954+319 during the 2008 flare could be well described by a thermal Comptonization model. We interpret the results within the framework of a recently developed quasi-spherical accretion model for symbiotic X-ray binaries.

  5. X-ray Polarimetry

    Science.gov (United States)

    Kallman, T.

    In spite of the recent advances in X-ray instrumentation, polarimetry remains an area which has been virtually unexplored in the last 20 years. The scientific motivation to study polarization has increased during this time: emission models designed to repro- duce X-ray spectra can be tested using polarization, and polarization detected in other wavelength bands makes clear predictions as to the X-ray polarization. Polarization remains the only way to infer geometrical properties of sources which are too small to be spatially resolved. At the same time, there has been recent progress in instrumen- tation which is likely to allow searches for X-ray polarization at levels significantly below what was possible for early detectors. In this talk I will review the history of X-ray polarimetry, discuss some experimental techniques and the scientific problems which can be addressed by future experiments.

  6. Analysis of the high resolution Mg XI x-ray spectra

    Energy Technology Data Exchange (ETDEWEB)

    Siarkowski, M.; Sylwester, J. (Polska Akademia Nauk, Wroclaw. Centrum Badan Kosmicznych); Bromboszcz, G. (Wrolaw Univ. (Poland). Astronomical Inst.); Korneev, V.V.; Mandelshtam, S.L.; Oparin, S.N.; Urnov, A.M.; Zhitnik, I.A. (AN SSSR, Moscow. Fizicheskij Inst.); Vasha, S. (Mongolian Academy of Sciences, Ulan Bator (USSR). Inst. of Physics and Technics)

    1982-04-01

    In this paper, the second in a series dealing with high-resolution spectra (9.14-9.33 A) measured on board the INTERCOSMOS-16 satellite, the analysis of the physical conditions in the coronal part of the McMath 14352 active regions is performed. The temperature structure of the emitting plasma is investigated on the basis of the photon fluxes measured in six selected wavelength bands involving the resonance, intercombination, and forbidden lines of the Mg XI ion and a number of satellite lines. Relative line intensities are discussed in terms of the active region plasma density.

  7. Influence of chemical bonding on X-ray spectra of different aluminium compounds

    Energy Technology Data Exchange (ETDEWEB)

    Bonetto, Rita [Centro de Investigacion y Desarrollo en Ciencias Aplicadas Dr. Jorge Ronco, Calle 47 No. 257, CC 59, 1900 La Plata (Argentina) and Consejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina (Argentina)]. E-mail: bonetto@quimica.unlp.edu.ar; Trincavelli, Jorge [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000, Cordoba (Argentina) and Consejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina (Argentina)]. E-mail: jorge@quechua.fis.uncor.edu; Vasconcellos, Marcos [Instituto de Fisica, Universidade Federal de Rio Grande do Sul, Campus do Vale, Av. Bento Goncalves 9500, CEP: 91501-970, Porto Alegre (Brazil)]. E-mail: marcos@if.ufrgs.br

    2005-11-15

    Five minerals containing aluminium in different crystal configurations are studied. The different kinds of chemical bonding between aluminium and oxygen originate molecular orbitals with energy levels and transition probabilities varying from one compound to another. This effect appears as shifts and changes in relative intensities of K{alpha} emission lines and as modifications of the K{beta} characteristic spectrum. In the present work, the aluminium K characteristic spectra obtained by means of an electron microprobe with a wavelength dispersive system are compared for topaz, albite, spodumene, biotite and corundum.

  8. Using measured 30-150 kVp polychromatic tungsten x-ray spectra to determine ion chamber calibration factors, Nx (Gy C(-1)).

    Science.gov (United States)

    Mercier, J R; Kopp, D T; McDavid, W D; Dove, S B; Lancaster, J L; Tucker, D M

    2000-10-01

    Two methods for determining ion chamber calibration factors (Nx) are presented for polychromatic tungsten x-ray beams whose spectra differ from beams with known Nx. Both methods take advantage of known x-ray fluence and kerma spectral distributions. In the first method, the x-ray tube potential is unchanged and spectra of differing filtration are measured. A primary standard ion chamber with known Nx for one beam is used to calculate the x-ray fluence spectrum of a second beam. Accurate air energy absorption coefficients are applied to the x-ray fluence spectra of the second beam to calculate actual air kerma and Nx. In the second method, two beams of differing tube potential and filtration with known Nx are used to bracket a beam of unknown Nx. A heuristically derived Nx interpolation scheme based on spectral characteristics of all three beams is described. Both methods are validated. Both methods improve accuracy over the current half value layer Nx estimating technique.

  9. Analysis of the high resolution Mg XI X-ray spectra. Pt. 3. Non-thermal interpretation of some spectra

    Energy Technology Data Exchange (ETDEWEB)

    Siarkowski, M.; Sylwester, J. (Polska Akademia Nauk, Wroclaw. Centrum Badan Kosmicznych); Bromboszcs, G. (Wroclaw Univ. (Poland). Obserwatorium Astronomiczne); Korneev, V.V.; Mandelshtam, S.L.; Oparin, S.N.; Urnov, A.M.; Zhitnik, I.A. (AN SSSR, Moscow. Fizicheskij Inst.)

    1982-11-01

    In part III of the paper containing the analysis of the INTERCOSMOS 16 ADP spectra, it is shown that by assuming the existence of a small admixture (1%) of non-thermal electrons in the active-region plasma it is possible to improve the agreement between measured and calculated fluxes for some spectra. The analysis follows the suggestion contained in the paper by Karev et al. (1980).

  10. Ab initio calculation of X-ray emission and IR spectra of the hydrofullerene C 60H 36

    Science.gov (United States)

    Bulusheva, L. G.; Okotrub, A. V.; Antich, A. V.; Lobach, A. S.

    2001-05-01

    Two isomers of the hydrofullerene C 60H 36 with T and D3 d symmetry were calculated using ab initio Hartree-Fock self-consistent field (HF-SCF). The T symmetry isomer in which the benzenoid rings occupy tetrahedral positions is predicted to be lower in energy than the other considered isomer. Simulated CK α spectra of the isomers were compared with the X-ray fluorescence spectrum of the hydrofullerene C 60H 36 prepared by the transfer hydrogenation method. The short-wave maximum intensity of the CK α spectrum of C 60H 36 was shown to be sensitive to the number of π electrons in the high-occupied levels of the molecule. Although the theoretical spectra are similar in appearance, the T isomer seems to be in better accordance with the experiment. Furthermore, the computed infrared frequencies and intensities for this isomer were found to correlate well with features in the measured spectrum of C 60H 36. The most intense peak in the low-frequency spectral region was shown to correspond to the skeletal vibrations of the benzenoid rings.

  11. Natural widths and Coster-Kronig transitions of L X-ray spectra in elements between Pd and Sb

    Energy Technology Data Exchange (ETDEWEB)

    Sakakura, Shusuke [Laboratory of Atomic and Molecular Physics, Institute for Chemical Research, Kyoto University, Uji, Kyoto 611 (Japan)]. E-mail: caligula@scl.kyoto-u.ac.jp; Oohashi, Hirofumi [Laboratory of Atomic and Molecular Physics, Institute for Chemical Research, Kyoto University, Uji, Kyoto 611 (Japan); Ito, Yoshiaki [Laboratory of Atomic and Molecular Physics, Institute for Chemical Research, Kyoto University, Uji, Kyoto 611 (Japan); Tochio, Tatsunori [Keihanna Interaction Plaza Inc., 1-7 Seika-cho, Soraku-gun, Kyoto 619-0237 (Japan); Vlaicu, Aurel M. [National Institute of Material Science, SPring-8, Mikazuki, Hyogo 679-5198 (Japan); Yoshikawa, Hideki [National Institute of Material Science, SPring-8, Mikazuki, Hyogo 679-5198 (Japan); Ikenaga, Eiji [Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Mikazuki-cho, Sayo-gun, Hyogo 679-5198 (Japan); Kobayashi, Keisuke [Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Mikazuki-cho, Sayo-gun, Hyogo 679-5198 (Japan)

    2006-11-15

    The L{alpha} and L{beta} X-ray emission spectra in the elements between Pd (Z=46) and Sb (Z=51) were measured using a high-resolution double-crystal vacuum spectrometer. The relative intensities of satellite structures, which originate in L {sub 1} L {sub 3} M {sub 4,5} Coster-Kronig transitions, were estimated to that of each diagram line, and compared with calculated values. According to the work of Chen et al. [1977a. Theoretical L-shell Coster-Kronig energies 11{<=}Z{<=}103. At. Data Nucl. Data Tables 19, 97-151], Salgueiro et al. [1987. J. Phys. (Paris) 48 Colloq. C9, 609] and Vlaicu et al. [1998. Investigation of the 74W L emission spectra and satellites. Phys. Rev. A 58, 3544] L {sub 1} L {sub 3} M {sub 4} Coster-Kronig transition is forbidden for 50{<=}Z{<=}77, and L {sub 1} L {sub 3} M {sub 5} Coster-Kronig transition is forbidden for 50{<=}Z{<=}73. The results suggest that L {sub 1} L {sub 3} M {sub 4,5} Coster-Kronig transitions may be allowed even for Sn (Z=50) and Sb (Z=51)

  12. On the Light Curve and Spectra of X-Rays and Gamma-Rays from the Crab Pulsar

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li; K. S. Cheng; MEI Dong-Cheng

    2000-01-01

    We use a three-dimensional pulsar magnetosphere model to study the light curve and spectra of x-rays and gamma-rays from the Crab pulsar. In this model, the vertical size of the outer gap is first determined by a self-consistent model in which the outer gap is limited by pair production from collisions of thermal photons produced by polar cap heating of backflow outer gap current and curvature photons emitted by gap accelerated charged particles. The transverse size of the outer gap is determined by local pair production conditions. In principle, there are two topologically disconnected outer gaps present in the magnetosphere of a pulsar, and both incoming and outgoing particle flows are allowed. However, double-peak light curves with strong bridges are most common, Making use of the three-dimensional structure of the outer gap and its local properties, we compare the results of our model with the light curve and phase-resolved spectra of the Crab pulsar.

  13. Bandpass Dependence of X-ray Temperatures in Galaxy Clusters

    CERN Document Server

    Cavagnolo, Kenneth W; Voit, G Mark; Sun, Ming

    2008-01-01

    We explore the band dependence of the inferred X-ray temperature of the intracluster medium (ICM) for 192 well-observed galaxy clusters selected from the Chandra Data Archive. If the hot ICM is nearly isothermal in the projected region of interest, the X-ray temperature inferred from a broad-band (0.7-7.0 keV) spectrum should be identical to the X-ray temperature inferred from a hard-band (2.0-7.0 keV) spectrum. However, if unresolved cool lumps of gas are contributing soft X-ray emission, the temperature of a best-fit single-component thermal model will be cooler for the broad-band spectrum than for the hard-band spectrum. Using this difference as a diagnostic, the ratio of best-fitting hard-band and broad-band temperatures may indicate the presence of cooler gas even when the X-ray spectrum itself may not have sufficient signal-to-noise to resolve multiple temperature components. To test this possible diagnostic, we extract X-ray spectra from core-excised annular regions for each cluster in our archival sam...

  14. The MUSCLES Treasury Survey. III. X-Ray to Infrared Spectra of 11 M and K Stars Hosting Planets

    Science.gov (United States)

    Loyd, R. O. P.; France, Kevin; Youngblood, Allison; Schneider, Christian; Brown, Alexander; Hu, Renyu; Linsky, Jeffrey; Froning, Cynthia S.; Redfield, Seth; Rugheimer, Sarah; Tian, Feng

    2016-06-01

    We present a catalog of panchromatic spectral energy distributions (SEDs) for 7 M and 4 K dwarf stars that span X-ray to infrared wavelengths (5 Å -5.5 μm). These SEDs are composites of Chandra or XMM-Newton data from 5-˜50 Å, a plasma emission model from ˜50-100 Å, broadband empirical estimates from 100-1170 Å, Hubble Space Telescope data from 1170-5700 Å, including a reconstruction of stellar Lyα emission at 1215.67 Å, and a PHOENIX model spectrum from 5700-55000 Å. Using these SEDs, we computed the photodissociation rates of several molecules prevalent in planetary atmospheres when exposed to each star’s unattenuated flux (“unshielded” photodissociation rates) and found that rates differ among stars by over an order of magnitude for most molecules. In general, the same spectral regions drive unshielded photodissociations both for the minimally and maximally FUV active stars. However, for O3 visible flux drives dissociation for the M stars whereas near-UV flux drives dissociation for the K stars. We also searched for an far-UV continuum in the assembled SEDs and detected it in 5/11 stars, where it contributes around 10% of the flux in the range spanned by the continuum bands. An ultraviolet continuum shape is resolved for the star ɛ Eri that shows an edge likely attributable to Si ii recombination. The 11 SEDs presented in this paper, available online through the Mikulski Archive for Space Telescopes, will be valuable for vetting stellar upper-atmosphere emission models and simulating photochemistry in exoplanet atmospheres.

  15. Mean glandular dose coefficients (D(g)N) for x-ray spectra used in contemporary breast imaging systems.

    Science.gov (United States)

    Nosratieh, Anita; Hernandez, Andrew; Shen, Sam Z; Yaffe, Martin J; Seibert, J Anthony; Boone, John M

    2015-09-21

    To develop tables of normalized glandular dose coefficients D(g)N for a range of anode-filter combinations and tube voltages used in contemporary breast imaging systems. Previously published mono-energetic D(g)N values were used with various spectra to mathematically compute D(g)N coefficients. The tungsten anode spectra from TASMICS were used; molybdenum and rhodium anode-spectra were generated using MCNPX Monte Carlo code. The spectra were filtered with various thicknesses of Al, Rh, Mo or Cu. An initial half value layer (HVL) calculation was made using the anode and filter material. A range of the HVL values was produced with the addition of small thicknesses of polymethyl methacrylate (PMMA) as a surrogate for the breast compression paddle, to produce a range of HVL values at each tube voltage. Using a spectral weighting method, D(g)N coefficients for the generated spectra were calculated for breast glandular densities of 0%, 12.5%, 25%, 37.5%, 50% and 100% for a range of compressed breast thicknesses from 3 to 8 cm. Eleven tables of normalized glandular dose (D(g)N) coefficients were produced for the following anode/filter combinations: W + 50 μm Ag, W + 500 μm Al, W + 700 μm Al, W + 200 μm Cu, W + 300 μm Cu, W + 50 μm Rh, Mo + 400 μm Cu, Mo + 30 μm Mo, Mo + 25 μm Rh, Rh + 400 μm Cu and Rh + 25 μm Rh. Where possible, these results were compared to previously published D(g)N values and were found to be on average less than 2% different than previously reported values.Over 200 pages of D(g)N coefficients were computed for modeled x-ray system spectra that are used in a number of new breast imaging applications. The reported values were found to be in excellent agreement when compared to published values.

  16. Mean Glandular dose coefficients (DgN) for x-ray spectra used in contemporary breast imaging systems

    Science.gov (United States)

    Nosratieh, Anita; Hernandez, Andrew; Shen, Sam Z.; Yaffe, Martin J.; Seibert, J. Anthony; Boone, John M.

    2015-01-01

    Purpose To develop tables of normalized glandular dose coefficients DgN for a range of anode–filter combinations and tube voltages used in contemporary breast imaging systems. Methods Previously published mono-energetic DgN values were used with various spectra to mathematically compute DgN coefficients. The tungsten anode spectra from TASMICS were used; Molybdenum and Rhodium anode-spectra were generated using MCNPx Monte Carlo code. The spectra were filtered with various thicknesses of Al, Rh, Mo or Cu. An initial HVL calculation was made using the anode and filter material. A range of the HVL values was produced with the addition of small thicknesses of polymethyl methacrylate (PMMA) as a surrogate for the breast compression paddle, to produce a range of HVL values at each tube voltage. Using a spectral weighting method, DgN coefficients for the generated spectra were calculated for breast glandular densities of 0%, 12.5%, 25%, 37.5%, 50% and 100% for a range of compressed breast thicknesses from 3 to 8 cm. Results Eleven tables of normalized glandular dose (DgN) coefficients were produced for the following anode/filter combinations: W + 50 μm Ag, W + 500 μm Al, W + 700 μm Al, W + 200 μm Cu, W + 300 μm Cu, W + 50 μm Rh, Mo + 400 μm Cu, Mo + 30 μm Mo, Mo + 25 μm Rh, Rh + 400 μm Cu and Rh + 25 μm Rh. Where possible, these results were compared to previously published DgN values and were found to be on average less than 2% different than previously reported values. Conclusion Over 200-pages of DgN coefficients were computed for modeled x-ray system spectra that are used in a number of new breast imaging applications. The reported values were found to be in excellent agreement when compared to published values. PMID:26348995

  17. The effect of broadband soft X-rays in SO2-containing ices: Implication on the photochemistry of ices towards young stellar objects

    CERN Document Server

    Pilling, S

    2015-01-01

    We investigate the effects produced mainly by broadband soft X-rays up to 2 keV (plus fast (keV) photoelectrons and low-energy (eV) induced secondary electrons) in the ice mixtures containing H2O:CO2:NH3:SO2 (10:1:1:1) at two different temperatures (50 K and 90 K). The experiments are an attempt to simulate the photochemical processes induced by energetic photons in SO2-containing ices present in cold environments in the ices surrounding young stellar objects (YSO) and in molecular clouds in the vicinity of star-forming regions, which are largely illuminated by soft X-rays. The measurements were performed using a high vacuum portable chamber from the Laboratorio de Astroquimica e Astrobiologia (LASA/UNIVAP) coupled to the spherical grating monochromator (SGM) beamline at the Brazilian Synchrotron Light Source (LNLS) in Campinas, Brazil. In-situ analyses were performed by a Fourier transform infrared (FTIR) spectrometer. Sample processing revealed the formation of several organic molecules, including nitriles,...

  18. X-ray selected BALQSOs

    CERN Document Server

    Page, M J; Ceballos, M; Corral, A; Ebrero, J; Esquej, P; Krumpe, M; Mateos, S; Rosen, S; Schwope, A; Streblyanska, A; Symeonidis, M; Tedds, J A; Watson, M G

    2016-01-01

    We study a sample of six X-ray selected broad absorption line (BAL) quasi-stellar objects (QSOs) from the XMM-Newton Wide Angle Survey. All six objects are classified as BALQSOs using the classic balnicity index, and together they form the largest sample of X-ray selected BALQSOs. We find evidence for absorption in the X-ray spectra of all six objects. An ionized absorption model applied to an X-ray spectral shape that would be typical for non-BAL QSOs (a power law with energy index alpha=0.98) provides acceptable fits to the X-ray spectra of all six objects. The optical to X-ray spectral indices, alpha_OX, of the X-ray selected BALQSOs, have a mean value of 1.69 +- 0.05, which is similar to that found for X-ray selected and optically selected non-BAL QSOs of similar ultraviolet luminosity. In contrast, optically-selected BALQSOs typically have much larger alpha_OX and so are characterised as being X-ray weak. The results imply that X-ray selection yields intrinsically X-ray bright BALQSOs, but their X-ray sp...

  19. Measurement of characteristic to total spectrum ratio of tungsten X-ray spectra for the validation of the modified Tbc model

    Energy Technology Data Exchange (ETDEWEB)

    Lopez G, A. H.; Costa, P. R. [University of Sao Paulo, Institute of Physics, Laboratory of Radiation Dosimetry and Medical Physics, Matao Street, alley R, 187, 66318 Sao Paulo (Brazil); Tomal, A., E-mail: ahlopezg@usp.br [Universidade Federal de Goias, Physics Institute, Campus Samambaia, 131 Goiania, Goias (Brazil)

    2014-08-15

    Primary X-ray spectra were measured in the range of 80 to 150 kV in order to validate a computer program based on a semiempirical model for X-ray spectra evaluation(tbc and mod). The ratio between the characteristic lines and total spectrum was considered for comparing the simulated results and experimental data. The raw spectra measured by the Cd Te detector were corrected by the detector efficiency, Compton effects and characteristic Cd and Te X-rays escape peaks, using a software specifically developed. The software Origin 8.5.1 was used to calculate the spectra and characteristic peaks areas. The obtained result shows that the experimental spectra have higher effective energy than the simulated spectra computed with tbc and mod software. The behavior of the ratio between the characteristic lines and total spectrum for simulated data presents discrepancy with the experimental result. Computed results are in good agreement with theoretical data published by Green, for spectra obtained with 3.04 mm of additional aluminum filtration. The difference of characteristic to total spectrum ratio between experimental and simulated data increases with the tube voltage. (Author)

  20. Relativistic X-ray reverberation modelling of the combined time-averaged and lag-energy spectra in AGN

    CERN Document Server

    Chainakun, P; Kara, E

    2016-01-01

    General relativistic ray tracing simulations of the time-averaged spectrum and energy-dependent time delays in AGN are presented. We model the lamp-post geometry in which the accreting gas is illuminated by an X-ray source located on the rotation axis of the black hole. The spectroscopic features imprinted in the reflection component are modelled using REFLIONX. The associated time delays after the direct continuum, known as reverberation lags, are computed including the full effects of dilution and ionization gradients on the disc. We perform, for the first time, simultaneous fitting of the time-averaged and lag-energy spectra in three AGN: Mrk 335, IRAS 13224-3809 and Ark 564 observed with XMM-Newton. The best fitting source height and central mass of each AGN partly agree with those previously reported. We find that including the ionization gradient in the model naturally explains lag-energy observations in which the 3 keV and 7-10 keV bands precede other bands. To obtain the clear 3 keV and 7-10 keV dips ...

  1. Application of an expectation maximization method to the reconstruction of X-ray-tube spectra from transmission data

    Energy Technology Data Exchange (ETDEWEB)

    Endrizzi, M., E-mail: m.endrizzi@ucl.ac.uk [Dipartimento di Fisica, Università di Siena, Via Roma 56, 53100 Siena (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Delogu, P. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Dipartimento di Fisica “E. Fermi”, Università di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Oliva, P. [Dipartimento di Chimica e Farmacia, Università di Sassari, via Vienna 2, 07100 Sassari (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Cagliari, s.p. per Monserrato-Sestu Km 0.700, 09042 Monserrato (Italy)

    2014-12-01

    An expectation maximization method is applied to the reconstruction of X-ray tube spectra from transmission measurements in the energy range 7–40 keV. A semiconductor single-photon counting detector, ionization chambers and a scintillator-based detector are used for the experimental measurement of the transmission. The number of iterations required to reach an approximate solution is estimated on the basis of the measurement error, according to the discrepancy principle. The effectiveness of the stopping rule is studied on simulated data and validated with experiments. The quality of the reconstruction depends on the information available on the source itself and the possibility to add this knowledge to the solution process is investigated. The method can produce good approximations provided that the amount of noise in the data can be estimated. - Highlights: • An expectation maximization method was used together with the discrepancy principle. • The discrepancy principle is a suitable criterion for stopping the iteration. • The method can be applied to a variety of detectors/experimental conditions. • The minimum information required is the amount of noise that affects the data. • Improved results are achieved by inserting more information when available.

  2. Temperature-dependent hard X-ray photoemission spectra of ternary Tl compounds with high Seebeck coefficient

    Energy Technology Data Exchange (ETDEWEB)

    Mimura, Kojiro; Ishizu, Takahiko; Yamamoto, Kazuya; Takasu, Junta; Yonehira, Yuri; Taguchi, Yukihiro; Ichikawa, Kouichi [Department of Mathematical Sciences, Graduate School of Engineering, Osaka Prefecture University, Sakai (Japan); Wakita, Kazuki [Department of Electrical, Electronics and Computer Engineering, Chiba Institute of Technology, Narashino, Chiba (Japan); Mamedov, Nazim [Institute of Physics, Azerbaijan National Academy of Sciences, Baku (Azerbaijan); Yan, Ke; Ikenaga, Eiji [Japan Synchrotron Radiation Research Institute, Kouto, Sayo-cho (Japan); Kobayashi, Keisuke [National Institute for Materials Science, Kouto, Sayo-cho, Sayo-gun, Hyogo (Japan)

    2009-05-15

    The temperature dependence of the core-level and valence-band electronic structures of TlGaTe{sub 2} and TlInSe{sub 2} that exhibits high values of Seebeck coefficient has been studied by hard X-ray photoemission spectroscopy over the temperature range 40-450 K. The relative peak position and peak width for Tl 4f, Ga 2p and Te 3d in TlGaTe{sub 2} are determined. It is shown that not only chemical shift defying the peak position but also electron-phonon interaction responsible for temperature line-broadening has rather peculiar temperature behaviour that reflects incommensurate phase transition. Thermoelectric power of TlGaTe{sub 2} is evaluated and found to be very close to that of TlInSe{sub 2}. It is shown that Tl 4f spectra of both compounds also display close similarity (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. LDA+DMFT calculations of X-ray absorption and x-ray circular dichroism spectra: Role of valence-band correlations

    Energy Technology Data Exchange (ETDEWEB)

    Sipr, Ondrej; Simunek, Antonin [Institute of Physics AS CR, Cukrovarnicka 10, Prague (Czech Republic); Minar, Jan; Ebert, Hubert [Universitaet Muenchen (Germany)

    2010-07-01

    L{sub 2,3}-edge XAS and XMCD spectra of 3d elements are calculated via a self-consistent LDA+DMFT method (including thus valence-band correlations). It is found that the asymmetry of the calculated XAS white lines increases upon inclusion of the correlations for Fe and Co but not for Ni. The change in the height of the L{sub 3} and L{sub 2} peaks in the XMCD spectra is in a good agreement with the change of the orbital magnetic moment caused by adding the valence-band correlations. As a whole, adding valence-band correlations improves the agreement between the theory and experiment but visible differences still remain. Therefore, a core hole is additionally accounted for via the final state approximation and the impact of such a procedure is assessed.

  4. Investigating ChaMPlane X-ray sources in the Galactic Bulge with Magellan LDSS2 spectra

    OpenAIRE

    Koenig, Xavier; Grindlay, Jonathan E.; Berg, Maureen van den; Laycock, Silas; Zhao, Ping; Hong, Jaesub; Schlegel, Eric M.

    2008-01-01

    We have carried out optical and X-ray spectral analyses on a sample of 136 candidate optical counterparts of X-ray sources found in five Galactic-bulge fields included in our Chandra Multi-wavelength Plane Survey. We use a combination of optical spectral fitting and quantile X-ray analysis to obtain the hydrogen column density towards each object, and a three-dimensional dust model of the Galaxy to estimate the most probable distance in each case. We present the discovery of a population of s...

  5. Broad-band X-ray spectral evolution of GX 339-4 during a state transition

    CERN Document Server

    Del Santo, M; Homan, J; Bazzano, A; Casella, P; Fender, R P; Gallo, E; Gehrels, N; Lewin, W H G; Méndez, M; Van der Klis, M

    2008-01-01

    We report on X-ray and soft gamma-ray observations of the black-hole candidate GX 339-4 during its 2007 outburst, performed with the RXTE and INTEGRAL satellites. The hardness-intensity diagram of all RXTE/PCA data combined shows a q-shaped track similar to that observed in previous outbursts.The evolution in the diagram suggested that a transition from hard-intermediate state to soft-intermediate state occurred, simultaneously with INTEGRAL observations performed in March. The transition is confirmed by the timing analysis presented in this work, which reveals that a weak type-A quasi-periodic oscillation (QPO) replaces a strong type-C QPO. At the same time, spectral analysis shows that the flux of the high-energy component shows a significant decrease in its flux. However, we observe a delay (roughly one day) between variations of the spectral parameters of the high-energy component and changes in the flux and timing properties. The changes in the high-energy component can be explained either in terms the h...

  6. Application of deconvolution techniques in X-ray spectra; Aplicacion de tecnica de deconvolucion en espectros de rayos X

    Energy Technology Data Exchange (ETDEWEB)

    Burgos Garcia, D.; Sancho Llerandi, C.; Saez Vergara, J. C.; Correa Garces, E.; Lanzas Sanchez, M. R.; Herbella Blazquez, M.

    2011-07-01

    The decay of Am-241, like that of Pu-239 is accompanied by the characteristic X-ray emission in this case, the Np-237. Being atomic number elements in a row, the X-ray emission of U (Z = 92) and Np (Z93) are very similar energies and thus inevitably overlapping photopeaks in the spectrum. This raises the question whether it is appropriate to try to separate their respective contributions in the spectrum, using spectral deconvolution techniques.

  7. Self-consistent modelling of X-ray photoelectron spectra from air-exposed polycrystalline TiN thin films

    Science.gov (United States)

    Greczynski, G.; Hultman, L.

    2016-11-01

    We present first self-consistent modelling of x-ray photoelectron spectroscopy (XPS) Ti 2p, N 1s, O 1s, and C 1s core level spectra with a cross-peak quantitative agreement for a series of TiN thin films grown by dc magnetron sputtering and oxidized to different extent by varying the venting temperature Tv of the vacuum chamber before removing the deposited samples. So-obtained film series constitute a model case for XPS application studies, where certain degree of atmosphere exposure during sample transfer to the XPS instrument is unavoidable. The challenge is to extract information about surface chemistry without invoking destructive pre-cleaning with noble gas ions. All TiN surfaces are thus analyzed in the as-received state by XPS using monochromatic Al Kα radiation (hν = 1486.6 eV). Details of line shapes and relative peak areas obtained from deconvolution of the reference Ti 2p and N 1 s spectra representative of a native TiN surface serve as an input to model complex core level signals from air-exposed surfaces, where contributions from oxides and oxynitrides make the task very challenging considering the influence of the whole deposition process at hand. The essential part of the presented approach is that the deconvolution process is not only guided by the comparison to the reference binding energy values that often show large spread, but in order to increase reliability of the extracted chemical information the requirement for both qualitative and quantitative self-consistency between component peaks belonging to the same chemical species is imposed across all core-level spectra (including often neglected O 1s and C 1s signals). The relative ratios between contributions from different chemical species vary as a function of Tv presenting a self-consistency check for our model. We propose that the cross-peak self-consistency should be a prerequisite for reliable XPS peak modelling as it enhances credibility of obtained chemical information, while relying

  8. Charge exchange recombination in X-ray spectra of He-like argon measured at the tokamak TEXTOR

    Energy Technology Data Exchange (ETDEWEB)

    Schlummer, Tobias

    2014-06-16

    Charge exchange recombination between ions and atomic hydrogen is an important atomic process in magnetically confined fusion plasmas. Besides radiative cooling of the plasma edge, charge exchange causes modifications of the ionization balance and the population densities of excited ion states. The central goal of this work is to investigate the influence of charge exchange on X-ray spectra measured at the tokamak TEXTOR. A new 2D X-ray spectrometer developed for future use at the stellarator W7-X was recently installed at TEXTOR. The spectrometer is optimized for measuring the K{sub α}-spectrum of He-like argon (1s2l - 1s{sup 2}) at wavelengths close to 4 Aa. K{sub α}-spectroscopy on He-like impurity ions is an established diagnostic for electron and ion temperature measurements in fusion plasmas. Still, up to now the observed intensity ratios of the K{sub α}-lines and their associated satellites are not fully understood. They show significant deviations from the predictions made by basic corona models. In the past charge exchange with the neutral particle background and radial impurity transport have been discussed as likely explanations. Yet a detailed description of the experimental spectra still has not been achieved. To reconstruct the 2D K{sub α}-spectra measured at TEXTOR the radial argon ion distribution is modeled using an impurity transport code. The model accounts for charge exchange and transport on basis of given radial profiles of the neutral particle density n{sub 0}(r) and the diffusion coefficient D {sub perpendicular} {sub to} (r). The theoretical spectrum is then constructed based on the processes relevant for line emission. Within an iterative procedure n{sub 0}(r) and D {sub perpendicular} {sub to} (r) are varied until consistency between the theoretical and the experimental spectra is achieved. It is shown that the 2D K{sub α}-spectra allow a clear distinction of charge exchange and transport effects, ensuring unique solutions for n

  9. Tungsten anode spectral model using interpolating cubic splines: Unfiltered x-ray spectra from 20 kV to 640 kV

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, Andrew M. [Biomedical Engineering Graduate Group, University of California Davis, Sacramento, California 95817 (United States); Boone, John M., E-mail: john.boone@ucdmc.ucdavis.edu [Departments of Radiology and Biomedical Engineering, Biomedical Engineering Graduate Group, University of California Davis, Sacramento, California 95817 (United States)

    2014-04-15

    Purpose: Monte Carlo methods were used to generate lightly filtered high resolution x-ray spectra spanning from 20 kV to 640 kV. Methods: X-ray spectra were simulated for a conventional tungsten anode. The Monte Carlo N-Particle eXtended radiation transport code (MCNPX 2.6.0) was used to produce 35 spectra over the tube potential range from 20 kV to 640 kV, and cubic spline interpolation procedures were used to create piecewise polynomials characterizing the photon fluence per energy bin as a function of x-ray tube potential. Using these basis spectra and the cubic spline interpolation, 621 spectra were generated at 1 kV intervals from 20 to 640 kV. The tungsten anode spectral model using interpolating cubic splines (TASMICS) produces minimally filtered (0.8 mm Be) x-ray spectra with 1 keV energy resolution. The TASMICS spectra were compared mathematically with other, previously reported spectra. Results: Using pairedt-test analyses, no statistically significant difference (i.e., p > 0.05) was observed between compared spectra over energy bins above 1% of peak bremsstrahlung fluence. For all energy bins, the correlation of determination (R{sup 2}) demonstrated good correlation for all spectral comparisons. The mean overall difference (MOD) and mean absolute difference (MAD) were computed over energy bins (above 1% of peak bremsstrahlung fluence) and over all the kV permutations compared. MOD and MAD comparisons with previously reported spectra were 2.7% and 9.7%, respectively (TASMIP), 0.1% and 12.0%, respectively [R. Birch and M. Marshall, “Computation of bremsstrahlung x-ray spectra and comparison with spectra measured with a Ge(Li) detector,” Phys. Med. Biol. 24, 505–517 (1979)], 0.4% and 8.1%, respectively (Poludniowski), and 0.4% and 8.1%, respectively (AAPM TG 195). The effective energy of TASMICS spectra with 2.5 mm of added Al filtration ranged from 17 keV (at 20 kV) to 138 keV (at 640 kV); with 0.2 mm of added Cu filtration the effective energy was 9

  10. Optical spectra of 5 new Be/X-ray Binaries in the Small Magellanic Cloud and the link of the supergiant B[e] star LHA 115-S 18 with an X-ray source

    CERN Document Server

    Maravelias, Grigoris; Antoniou, Vallia; Hatzidimitriou, Despoina

    2013-01-01

    The Small Magellanic Cloud (SMC) is well known to harbor a large number of High-Mass X-ray Binaries (HMXBs). The identification of their optical counterparts provides information on the nature of the donor stars and can help to constrain the parameters of these systems and their evolution. We obtained optical spectra for a number of HMXBs identified in previous Chandra and XMM-Newton surveys of the SMC using the AAOmega/2dF fiber-fed spectrograph at the Anglo-Australian Telescope. We find 5 new Be/X-ray binaries (BeXRBs; including a tentative one), by identifying the spectral type of their optical counterparts, and we confirm the spectral classification of an additional 15 known BeXRBs. We compared the spectral types, orbital periods, and eccentricities of the BeXRB populations in the SMC and the Milky Way and we find marginal evidence for difference between the spectral type distributions, but no statistically significant differences for the orbital periods and the eccentricities. Moreover, our search reveal...

  11. Characterizing X-ray and Radio emission in the Black Hole X-Ray Binary V404 Cygni during Quiescence

    CERN Document Server

    Rana, Vikram; Corbel, Stephane; Tomsick, John A; Chakrabarty, Deepto; Walton, Dominic J; Barret, Didier; Boggs, Steven E; Christensen, Finn E; Craig, William; Fuerst, Felix; Gandhi, Poshak; Grefenstette, Brian W; Hailey, Charles; Harrison, Fiona A; Madsen, Kristin K; Rahoui, Farid; Stern, Daniel; Tendulkar, Shriharsh; Zhang, William W

    2015-01-01

    We present results from multi-wavelength simultaneous X-ray and radio observations of the black hole X-ray binary V404 Cyg in quiescence. Our coverage with NuSTAR provides the very first opportunity to study the X-ray spectrum of V404 Cyg at energies above 10 keV. The unabsorbed broad-band (0.3-30 keV) quiescent luminosity of the source is 8.9$\\times$10$^{32}$ erg s$^{-1}$ for a distance of 2.4 kpc. The source shows clear variability on short time scales in radio, soft X-ray and hard X-ray bands in the form of multiple flares. The broad-band X-ray spectra obtained from XMM-Newton and NuSTAR can be characterized with a power-law model having photon index {\\Gamma}=2.13$\\pm$0.07 (90% confidence errors); however, residuals at high energies indicate spectral curvature significant at a 3{\\sigma} confidence level with e-folding energy of the cutoff to be 19$^{+19}_{-7}$ keV. Such curvature can be explained using synchrotron emission from the base of a jet outflow. Radio observations using the JVLA reveal that the sp...

  12. Incorporation of AgI clusters into the cages of zeolites LTA and FAU observed by optical spectra and X-ray diffraction patterns

    Science.gov (United States)

    Kodaira, Tetsuya; Ikeda, Takuji; Takeo, Harutoshi

    1999-02-01

    The loading of AgI into the cages of zeolites LTA and FAU was performed by vapor-phase adsorption. The successful incorporation of AgI clusters into the cages was confirmed by optical absorption spectra and X-ray powder diffraction patterns. Large blue shifts of the absorption edges were observed in the spectra of adsorbed AgI to both zeolites, compared with the lowest excited state of AgI in the bulk. The present observation of the shift implies that a strong quantum confinement in the photoexcited state of AgI occurs, which leads to the conclusion that AgI clusters have been formed in the cages. In the X-ray powder diffraction pattern of AgI-loaded LTA, superlattice reflection peaks are observed which cannot be assigned either to the reflection of LTA or the AgI in the bulk.

  13. FEEDBACK FROM HIGH-MASS X-RAY BINARIES ON THE HIGH-REDSHIFT INTERGALACTIC MEDIUM: MODEL SPECTRA

    Energy Technology Data Exchange (ETDEWEB)

    Power, Chris [International Centre for Radio Astronomy Research, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia); James, Gillian; Wynn, Graham [Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH (United Kingdom); Combet, Celine, E-mail: chris.power@icrar.org [Laboratoire de Physique Subatomique et de Cosmologie, Universite Joseph Fourier Grenoble 1/CNRS/IN2P3/INPG, 53 avenue des Martyrs, F-38026 Grenoble (France)

    2013-02-10

    Massive stars at redshifts z {approx}> 6 are predicted to have played a pivotal role in cosmological reionization as luminous sources of ultraviolet (UV) photons. However, the remnants of these massive stars could be equally important as X-ray-luminous (L{sub X} {approx} 10{sup 38} erg s{sup -1}) high-mass X-ray binaries (HMXBs). Because the absorption cross section of neutral hydrogen decreases sharply with photon energy ({sigma}{proportional_to}E {sup -3}), X-rays can escape more freely than UV photons from the star-forming regions in which they are produced, allowing HMXBs to make a potentially significant contribution to the ionizing X-ray background during reionization. In this paper, we explore the ionizing power of HMXBs at redshifts z {approx}> 6 using a Monte Carlo model for a coeval stellar population of main-sequence stars and HMXBs. Using the archetypal Galactic HMXB Cygnus X-1 as our template, we propose a composite HMXB spectral energy distribution consisting of blackbody and power-law components, whose contributions depend on the accretion state of the system. We determine the time-dependent ionizing power of a combined population of UV-luminous stars and X-ray-luminous HMXBs and deduce fitting formulae for the boost in the population's ionizing power arising from HMXBs; these fits allow for simple implementation of HMXB feedback in numerical simulations. Based on this analysis, we estimate the contribution of high-redshift HMXBs to the present-day soft X-ray background, and we show that it is a factor of {approx}100-1000 smaller than the observed limit. Finally, we discuss the implications of our results for the role of HMXBs in reionization and in high-redshift galaxy formation.

  14. X-rays from the jet in 3C 273 clues from the radio-optical spectra

    CERN Document Server

    Jester, S; Meisenheimer, K; Perley, R

    2002-01-01

    Using new deep VLA and HST observations of the large-scale jet in 3C273 matched to 0.3" resolution, we have detected excess near-ultraviolet emission (300 nm) above a synchrotron cutoff spectrum accounting for the emission from radio through optical (3.6 cm - 620 nm). This necessitates a two-component model for the emission. The radio-optical-X-ray spectral energy distributions suggest a common origin for the UV excess and the X-rays from the jet.

  15. Ab initio calculations of X-ray magnetic circular dichroism spectra within the projector augmented wave method: An implementation into the VASP code

    Science.gov (United States)

    Dixit, Anant; Alouani, M.

    2016-10-01

    X-ray absorption and X-ray magnetic circular dichroism (XMCD) are very powerful tools for probing the orbital and spin moments of each atomic species orbital of magnetic materials. In this work, we present the implementation of a module for computing the X-ray absorption and XMCD spectra into the VASP code. We provide a derivation of the absorption cross-section in the electric dipole approximation. The matrix elements, which make up the X-ray absorption cross-section for a given polarization of light, are then computed using either the momentum operator p or the position operator r, within the projector augmented wave method. The core electrons are described using the relativistic basis-set whereas for the valence electrons, the spin-orbit coupling is added perturbatively to the semi-relativistic Hamiltonian. We show that both the p and the r implementations lead to the same results. The results for the K-edge and L23-edges of bcc-iron are then computed and compared to experiment.

  16. Core-collapse model of broadband emission from SNR RX J1713.7-3946 with thermal X-rays and Gamma-rays from escaping cosmic rays

    CERN Document Server

    Ellison, Donald C; Patnaude, Daniel J; Bykov, Andrei M

    2011-01-01

    We present a spherically symmetric, core-collapse model of SNR RX J1713.7-3946 that includes a hydrodynamic simulation of the remnant evolution coupled to the efficient production of cosmic rays (CRs) by nonlinear diffusive shock acceleration (DSA). High-energy CRs that escape from the forward shock (FS) are propagated in surrounding dense material that simulates either a swept-up, pre-supernova shell or a nearby molecular cloud. The continuum emission from trapped and escaping CRs, along with the thermal X-ray emission from the shocked heated ISM behind the FS, integrated over the remnant, is compared against broadband observations. Our results show conclusively that, overall, the GeV-TeV emission is dominated by inverse-Compton from CR electrons if the supernova is isolated regardless of its type, i.e., not interacting with a >>100 Msun shell or cloud. If the SNR is interacting with a much larger mass >10^4 Msun, pion-decay from the escaping CRs may dominate the TeV emission, although a precise fit at high ...

  17. X-ray Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yano, Junko; Yachandra, Vittal K.

    2009-07-09

    This review gives a brief description of the theory and application of X-ray absorption spectroscopy, both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), especially, pertaining to photosynthesis. The advantages and limitations of the methods are discussed. Recent advances in extended EXAFS and polarized EXAFS using oriented membranes and single crystals are explained. Developments in theory in understanding the XANES spectra are described. The application of X-ray absorption spectroscopy to the study of the Mn4Ca cluster in Photosystem II is presented.

  18. Nitrogen K-edge X-ray absorption near edge structure (XANES) spectra of purine-containing nucleotides in aqueous solution.

    Science.gov (United States)

    Shimada, Hiroyuki; Fukao, Taishi; Minami, Hirotake; Ukai, Masatoshi; Fujii, Kentaro; Yokoya, Akinari; Fukuda, Yoshihiro; Saitoh, Yuji

    2014-08-07

    The N K-edge X-ray absorption near edge structure (XANES) spectra of the purine-containing nucleotide, guanosine 5'-monophosphate (GMP), in aqueous solution are measured under various pH conditions. The spectra show characteristic peaks, which originate from resonant excitations of N 1s electrons to π* orbitals inside the guanine moiety of GMP. The relative intensities of these peaks depend on the pH values of the solution. The pH dependence is explained by the core-level shift of N atoms at specific sites caused by protonation and deprotonation. The experimental spectra are compared with theoretical spectra calculated by using density functional theory for GMP and the other purine-containing nucleotides, adenosine 5'-monophosphate, and adenosine 5'-triphosphate. The N K-edge XANES spectra for all of these nucleotides are classified by the numbers of N atoms with particular chemical bonding characteristics in the purine moiety.

  19. A broadband x-ray study of the Geminga pulsar with NuSTAR and XMM-Newton

    DEFF Research Database (Denmark)

    Mori, Kaya; Gotthelf, Eric V.; Dufour, Francois;

    2014-01-01

    phase-integrated spectra over the 0.2-20 keV band with NuSTAR and archival XMM-Newton data do not fit to a conventional two-component model of a blackbody plus power law, but instead exhibit spectral hardening above ~5 keV. We find that two spectral models fit the data well: (1) a blackbody (kT1 ~ 42 e......V) with a broken power law (Γ1 ~ 2.0, Γ2 ~ 1.4 and Ebreak ~ 3.4 keV) and (2) two blackbody components (kT1 ~ 44 eV and kT2 ~ 195 eV) with a power-law component (Γ ~ 1.7). In both cases, the extrapolation of the Rayleigh-Jeans tail of the thermal component is consistent with the UV data, while the non......-thermal component overpredicts the near-infrared data, requiring a spectral flattening at E ~ 0.05-0.5 keV. While strong phase variation of the power-law index is present below ~5 keV, our phase-resolved spectroscopy with NuSTAR indicates that another hard non-thermal component with Γ ~ 1.3 emerges above ~5 ke...

  20. Application of a relativistic accretion disc model to X-ray spectra of LMC X-1 and GRO J1655-40

    CERN Document Server

    Gierlinski, M; Ebisawa, K; Gierlinski, Marek; Maciolek-Niedzwiecki, Andrzej; Ebisawa, Ken

    2001-01-01

    We present a general relativistic accretion disc model and its application to the soft-state X-ray spectra of black hole binaries. The model assumes a flat, optically thick disc around a rotating Kerr black hole. The disc locally radiates away the dissipated energy as a blackbody. Special and general relativistic effects influencing photons emitted by the disc are taken into account. The emerging spectrum, as seen by a distant observer, is parametrized by the black hole mass and spin, the accretion rate, the disc inclination angle and the inner disc radius. We fit the ASCA soft state X-ray spectra of LMC X-1 and GRO J1655-40 by this model. We find that having additional limits on the black hole mass and inclination angle from optical/UV observations, we can constrain the black hole spin from X-ray data. In LMC X-1 the constrain is weak, we can only rule out the maximally rotating black hole. In GRO J1655-40 we can limit the spin much better, and we find 0.68 < a < 0.88. Accretion discs in both sources a...

  1. Iron-line and continuum variations in the XMM-Newton and Suzaku spectra of the neutron-star low-mass X-ray binary 4U 1636-53

    NARCIS (Netherlands)

    Lyu, Ming; Méndez, Mariano; Sanna, Andrea; Homan, Jeroen; Belloni, Tomaso; Hiemstra, Beike

    2014-01-01

    We used six simultaneous XMM-Newton and Rossi X-ray Timing Explorer plus five Suzaku observations to study the continuum spectrum and the iron emission line in the neutron-star low-mass X-ray binary 4U 1636-53. We modelled the spectra with two thermal components (representing the accretion disc and

  2. Ti K-edge X-ray absorption spectra of spray pyrolysis synthesized TiO2-x and TiO2-x Nx thin films

    Science.gov (United States)

    Sahoo, Madhusmita; Yadav, Ashok Kumar; Jha, S. N.; Bhattacharyya, Dibyendu; Mathews, Tom; Dash, S.

    2017-05-01

    Oxygen deficient TiO2 and N-TiO2 anatase thin films were synthesized by employing a two step process. First TiO2 and N-TiO2 films were synthesized by using a cost effective spray pyrolysis method. Subsequently, these films were reduced under H2 to create oxygen vacancies. Formation of oxygen vacancies was confirmed by using synchrotron source X-ray Absorption Spectroscopy (XAS). Effect of oxygen vacancies on electronic and structural properties were deduced from the near edge and extended region analysis of the X-ray absorption spectra. It is inferred that reduction time plays a crucial role in creating oxygen vacancies and number of oxygen vacancies increases with increase in reduction time. Substrate effect was delineated by using Si and FTO (Fluorine doped tin oxide coated glass) as substrates for film deposition.

  3. Li K-edge X-ray absorption near edge structure spectra for a library of lithium compounds applied in lithium batteries

    Science.gov (United States)

    Wang, Dongniu; Zuin, Lucia

    2017-01-01

    Lithium ion batteries (LIB) have achieved great success as energy supply systems in portable devices and in electrical vehicles. Identifying the local chemical structures of elemental lithium in lithium compounds is beneficial for improving understanding of battery components and performance. Herein, a library of Li K-edge X-ray absorption near edge structure (XANES) of lithium compounds relevant to Li-ion batteries is reported. Materials described include lithium metals (anode), Li-containing cathodes, electrolytes and solid electrolyte interphase (SEI). The results illustrate the characteristic spectral features stemming from the various electronic structures and chemical environment of lithium atoms for each and every possible battery component. XANES spectra of Sn based anode after discharging reveal the appearance of Li2CO3 on electrode surface. X-ray damage on sensitive lithium species is also assessed; the results reveal that more attention should be paid to irradiation effects to conduct XANES measurements for battery materials properly.

  4. Orbital breathing effects in the computation of x-ray d-ion spectra in solids by ab initio wave-function-based methods

    Science.gov (United States)

    Bogdanov, Nikolay A.; Bisogni, Valentina; Kraus, Roberto; Monney, Claude; Zhou, Kejin; Schmitt, Thorsten; Geck, Jochen; Mitrushchenkov, Alexander O.; Stoll, Hermann; van den Brink, Jeroen; Hozoi, Liviu

    2017-01-01

    In existing theoretical approaches to core-level excitations of transition-metal ions in solids relaxation and polarization effects due to the inner core hole are often ignored or described phenomenologically. Here we set up an ab initio computational scheme that explicitly accounts for such physics in the calculation of x-ray absorption and resonant inelastic x-ray scattering spectra. Good agreement is found with experimental transition-metal L-edge data for the strongly correlated d 9 cuprate Li2CuO2, for which we determine the absolute scattering intensities. The newly developed methodology opens the way for the investigation of even more complex d n electronic structures of group VI B to VIII B correlated oxide compounds.

  5. Interpretation of the Si Kα x-ray spectra accompanying the stopping of swift Ca ions in low-density SiO2 aerogel

    Science.gov (United States)

    Rzadkiewicz, J.; Gojska, A.; Rosmej, O.; Polasik, M.; Słabkowska, K.

    2010-07-01

    This article presents a detailed analysis of the Kα x-ray spectra of Si induced by 11.4 MeV/u Ca projectiles penetrating a low-density SiO2 aerogel target measured with high spectral and spatial resolution at the UNILAC accelerator at GSI-Darmstadt. The low-density material used in the experiment was crucial for the space-resolved studies of the Si x-ray radiation (for different energies of stopping Ca ions). The stopping length of the 11 MeV/u Ca ions reaches up to 10 mm in the low-density SiO2 aerogel, whereas in regular quartz solid targets it is about 100 times shorter. The analysis of the x-ray spectra emitted by the stopping medium has shown a high level of the L-shell ionization, especially in the later considered phase (Ep~5 MeV/u) of the stopping process. It has been further demonstrated that the population of the highly ionized states produced in the ion-atom collisions can be substantially reduced in the time between the collision and the x-ray emission due to the very intense rearrangement processes occurring in Si situated in the chemical environment of oxygen atoms. Moreover, comparison of the experimental values of the Kα L-shell satellite energy shifts with the results of the multiconfiguration Dirac-Fock calculations allows us to find that Si valence electron configuration is enriched due to electron transfer from valence-electron-rich oxygen atoms into highly ionized silicon atoms. Our results indicate that the Coulomb explosion in a highly ionized track core is prevented by rapid neutralization in the femtosecond time scale.

  6. Detailed analysis of hollow ions spectra from dense matter pumped by X-ray emission of relativistic laser plasma

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, S. B., E-mail: sbhanse@sandia.gov, E-mail: anatolyf@hotmail.com [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States); Colgan, J.; Abdallah, J. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Faenov, A. Ya., E-mail: sbhanse@sandia.gov, E-mail: anatolyf@hotmail.com [Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412 (Russian Federation); Quantum Beam Science Directorate, Japan Atomic Energy Agency, Kyoto 619-0215 (Japan); Pikuz, S. A.; Skobelev, I. Yu. [Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412 (Russian Federation); Wagenaars, E.; Culfa, O.; Dance, R. J.; Tallents, G. J.; Rossall, A. K.; Woolsey, N. C. [York Plasma Institute, Department of Physics, University of York, York YO10 5DD (United Kingdom); Booth, N.; Lancaster, K. L. [Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX (United Kingdom); Evans, R. G. [Department of Physics, Imperial College, London SW7 2AZ (United Kingdom); Gray, R. J.; McKenna, P. [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 ONG (United Kingdom); Kaempfer, T.; Schulze, K. S. [Helmholtzinstitut Jena, Jena D-07743 (Germany); Uschmann, I. [Helmholtzinstitut Jena, Jena D-07743 (Germany); Institut für Optik und Quantenelektronic, Friedrich-Schiller-Universität Jena, Max-Wien Platz 1, Jena, D-07743 (Germany); and others

    2014-03-15

    X-ray emission from hollow ions offers new diagnostic opportunities for dense, strongly coupled plasma. We present extended modeling of the x-ray emission spectrum reported by Colgan et al. [Phys. Rev. Lett. 110, 125001 (2013)] based on two collisional-radiative codes: the hybrid-structure Spectroscopic Collisional-Radiative Atomic Model (SCRAM) and the mixed-unresolved transition arrays (MUTA) ATOMIC model. We show that both accuracy and completeness in the modeled energy level structure are critical for reliable diagnostics, investigate how emission changes with different treatments of ionization potential depression, and discuss two approaches to handling the extensive structure required for hollow-ion models with many multiply excited configurations.

  7. Chemical and physical parameters from X-ray high resolution spectra of the Galactic nova V959 Mon

    CERN Document Server

    Peretz, U; Behar, E; Bianchini, A; Gallagher, J; Rauch, T; Tofflemire, B; Zemko, P

    2016-01-01

    Two observations of V959 Mon, done using the Chandra X-ray gratings during the late outburst phases (2012 September and December), offer extraordinary insight into the physics and chemistry of this Galactic ONe nova. the X-ray flux was 1.7 x 10(-11) erg/cm(2)/s and 8.6 x 10(-12) erg/cm(2)/s, respectively at the two epochs. The first result, coupled with electron density diagnostics and compared with published optical and ultraviolet observations, indicates that most likely in 2012 September the X-rays originate from a very small fraction of the ejecta, concentrated in very dense clumps. We obtained a fairly good fit to the September spectrum with a model of plasma in collisional ionization equilibrium (CIE) with two components; one at a temperature of 0.78 keV, blueshifted by 710-930 km/s, the other at a temperature of 4.5 keV, mostly contributing to the high-energy continuum. However, we cannot rule out a range of plasma temperatures between these two extremes. In December, the central white dwarf (WD) becam...

  8. Investigation of slow collisions for (quasi) symmetric heavy systems: what can be extracted from high resolution X-ray spectra

    CERN Document Server

    Trassinelli, Martino; Lamour, Emily; Mezdari, Férid; Merot, Jacques; Reuschl, Regina; Rozet, Jean-Pierre; Steydli, S; Vernhet, Dominique

    2012-01-01

    We present a new experiment on (quasi) symmetric collision systems at low-velocity, namely Ar$^{17+}$ ions ($v=0.53$ a.u.) on gaseous Ar and N$_2$ targets, using low- and high-resolution X-ray spectroscopy. Thanks to an accurate efficiency calibration of the spectrometers, we extract absolute X-ray emission cross sections combining low-resolution X-ray spectroscopy and a complete determination of the ion beam - gas jet target overlap. Values with improved uncertainty are found in agreement with previous results \\cite{Tawara2001}. Resolving the whole He-like Ar$^{16+}$ Lyman series from $n=2$ to 10 with our crystal spectrometer enables to determine precisely the distribution ${\\mathcal{P}_n}$ of the electron capture probability and the preferential $n_{pref}$ level of the selective single-electron capture. Evaluation of cross sections for this process as well as for the contribution of multiple-capture is carried out. Their sensitivity to the $\\ell$-distribution of $n$ levels populated by single-electron captu...

  9. Skull x-ray

    Science.gov (United States)

    X-ray - head; X-ray - skull; Skull radiography; Head x-ray ... There is low radiation exposure. X-rays are monitored and regulated to provide the minimum amount of radiation exposure needed to produce the image. Most ...

  10. Neck x-ray

    Science.gov (United States)

    X-ray - neck; Cervical spine x-ray; Lateral neck x-ray ... There is low radiation exposure. X-rays are monitored so that the lowest amount of radiation is used to produce the image. Pregnant women and ...

  11. Analysis of the additional filtration effects in X-ray beams from the calculation of average energy for photon in X-ray spectra; Analise dos efeitos da filtracao adicional em feixes de raios X a partir dos calculos de energia media por foton em espectros de raios X

    Energy Technology Data Exchange (ETDEWEB)

    Lucena, Rodrigo F.; Potiens, Maria da Penha A., E-mail: rodrigoifusp@yahoo.com.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-12-15

    The objective of this work was to analyze the behavior of X-ray spectra by calculating the average energy in each spectrum generated for different additional filtrations inserted in the X-ray beam. It was used an X-ray system present in the Laboratory of Instruments Calibration of the Instituto de Pesquisas Energeticas e Nucleares (IPEN) for the generation of X-ray beams, a spectrometry system with a solid state detector (semiconductor) to the data acquisition and aluminum and copper filters, with different thicknesses to be inserted in the output of the X-ray tube. The average energy per photon was calculated integrating the curve of each spectrum and dividing the value by the total number of counts. This calculation enabled to verify that the use of filtration in the X-ray equipment contributes significantly in the average energy of the X-ray beam. Thus, the same dose received by a patient or recorded by a detector has distinct average energies due to the use of filtrations with different materials and thicknesses, which allows the manipulation of X-ray beam through additional filtration. (author)

  12. NuSTAR Hard X-ray Survey of the Galactic Center Region I: Hard X-ray Morphology and Spectroscopy of the Diffuse Emission

    CERN Document Server

    Mori, Kaya; Krivonos, Roman; Hong, Jaesub; Ponti, Gabriele; Bauer, Franz; Perez, Kerstin; Nynka, Melania; Zhang, Shuo; Tomsick, John A; Alexander, David M; Baganoff, Frederick K; Barret, Didier; Barriere, Nicolas; Boggs, Steven E; Canipe, Alicia M; Christensen, Finn E; Craig, William W; Forster, Karl; Giommi, Paolo; Grefenstette, Brian W; Grindlay, Jonathan E; Harrison, Fiona A; Hornstrup, Allan; Kitaguchi, Takao; Koglin, Jason E; Luu, Vy; Madsen, Kristen K; Mao, Peter H; Miyasaka, Hiromasa; Perri, Matteo; Pivovaroff, Michael J; Puccetti, Simonetta; Rana, Vikram; Stern, Daniel; Westergaard, Niels J; Zhang, William W; Zoglauer, Andreas

    2015-01-01

    We present the first sub-arcminute images of the Galactic Center above 10 keV, obtained with NuSTAR. NuSTAR resolves the hard X-ray source IGR J17456-2901 into non-thermal X-ray filaments, molecular clouds, point sources and a previously unknown central component of hard X-ray emission (CHXE). NuSTAR detects four non-thermal X-ray filaments, extending the detection of their power-law spectra with $\\Gamma\\sim1.3$-$2.3$ up to ~50 keV. A morphological and spectral study of the filaments suggests that their origin may be heterogeneous, where previous studies suggested a common origin in young pulsar wind nebulae (PWNe). NuSTAR detects non-thermal X-ray continuum emission spatially correlated with the 6.4 keV Fe K$\\alpha$ fluorescence line emission associated with two Sgr A molecular clouds: MC1 and the Bridge. Broad-band X-ray spectral analysis with a Monte-Carlo based X-ray reflection model self-consistently determined their intrinsic column density ($\\sim10^{23}$ cm$^{-2}$), primary X-ray spectra (power-laws wi...

  13. Measurement of high-dynamic range x-ray Thomson scattering spectra for the characterization of nano-plasmas at LCLS

    Energy Technology Data Exchange (ETDEWEB)

    MacDonald, M. J., E-mail: macdonm@umich.edu [University of Michigan, Ann Arbor, Michigan 48109 (United States); SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Gorkhover, T. [SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Technische Universität, 10623 Berlin (Germany); Bachmann, B.; Hau-Riege, S. P.; Pardini, T.; Döppner, T. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Bucher, M. [SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Argonne National Lab, Lemont, Illinois 60439 (United States); Carron, S. [California Lutheran University, Thousand Oaks, California 91360 (United States); Coffee, R. N.; Fletcher, L. B.; Gamboa, E. J.; Glenzer, S. H.; Göde, S.; Krzywinski, J.; O’Grady, C. P.; Osipov, T.; Swiggers, M. [SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Drake, R. P. [University of Michigan, Ann Arbor, Michigan 48109 (United States); Ferguson, K. R. [SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Stanford University, Stanford, California 94305 (United States); Kraus, D. [University of California, Berkeley, California 94720 (United States); and others

    2016-11-15

    Atomic clusters can serve as ideal model systems for exploring ultrafast (∼100 fs) laser-driven ionization dynamics of dense matter on the nanometer scale. Resonant absorption of optical laser pulses enables heating to temperatures on the order of 1 keV at near solid density conditions. To date, direct probing of transient states of such nano-plasmas was limited to coherent x-ray imaging. Here we present the first measurement of spectrally resolved incoherent x-ray scattering from clusters, enabling measurements of transient temperature, densities, and ionization. Single shot x-ray Thomson scattering signals were recorded at 120 Hz using a crystal spectrometer in combination with a single-photon counting and energy-dispersive pnCCD. A precise pump laser collimation scheme enabled recording near background-free scattering spectra from Ar clusters with an unprecedented dynamic range of more than 3 orders of magnitude. Such measurements are important for understanding collective effects in laser-matter interactions on femtosecond time scales, opening new routes for the development of schemes for their ultrafast control.

  14. Measurement of high-dynamic range x-ray Thomson scattering spectra for the characterization of nano-plasmas at LCLS

    Science.gov (United States)

    MacDonald, M. J.; Gorkhover, T.; Bachmann, B.; Bucher, M.; Carron, S.; Coffee, R. N.; Drake, R. P.; Ferguson, K. R.; Fletcher, L. B.; Gamboa, E. J.; Glenzer, S. H.; Göde, S.; Hau-Riege, S. P.; Kraus, D.; Krzywinski, J.; Levitan, A. L.; Meiwes-Broer, K.-H.; O'Grady, C. P.; Osipov, T.; Pardini, T.; Peltz, C.; Skruszewicz, S.; Swiggers, M.; Bostedt, C.; Fennel, T.; Döppner, T.

    2016-11-01

    Atomic clusters can serve as ideal model systems for exploring ultrafast (˜100 fs) laser-driven ionization dynamics of dense matter on the nanometer scale. Resonant absorption of optical laser pulses enables heating to temperatures on the order of 1 keV at near solid density conditions. To date, direct probing of transient states of such nano-plasmas was limited to coherent x-ray imaging. Here we present the first measurement of spectrally resolved incoherent x-ray scattering from clusters, enabling measurements of transient temperature, densities, and ionization. Single shot x-ray Thomson scattering signals were recorded at 120 Hz using a crystal spectrometer in combination with a single-photon counting and energy-dispersive pnCCD. A precise pump laser collimation scheme enabled recording near background-free scattering spectra from Ar clusters with an unprecedented dynamic range of more than 3 orders of magnitude. Such measurements are important for understanding collective effects in laser-matter interactions on femtosecond time scales, opening new routes for the development of schemes for their ultrafast control.

  15. An Integrated Model for the Production of X-Ray Time Lags and Quiescent Spectra from Homogeneous and Inhomogeneous Black Hole Accretion Coronae

    CERN Document Server

    Kroon, John J

    2016-01-01

    Many accreting black holes manifest time lags during outbursts, in which the hard Fourier component typically lags behind the soft component. Despite decades of observations of this phenomenon, the underlying physical explanation for the time lags has remained elusive, although there are suggestions that Compton reverberation plays an important role. However, the lack of analytical solutions has hindered the interpretation of the available data. In this paper, we investigate the generation of X-ray time lags in Compton scattering coronae using a new mathematical approach based on analysis of the Fourier-transformed transport equation. By solving this equation, we obtain the Fourier transform of the radiation Green's function, which allows us to calculate the exact dependence of the time lags on the Fourier frequency, for both homogeneous and inhomogeneous coronal clouds. We use the new formalism to explore a variety of injection scenarios, including both monochromatic and broadband (bremsstrahlung) seed photo...

  16. Comparison of x-ray absorption spectra between water and ice: New ice data with low pre-edge absorption cross-section

    OpenAIRE

    Kaya, Sarp; Sellberg, Jonas A.; Segtnan, Vegard H.; Chen, Chen; Tyliszczak, Tolek; Ogasawara, Hirohito; Nordlund, Dennis; Pettersson, Lars G. M.; Nilsson, Anders

    2014-01-01

    The effect of crystal growth conditions on the O K-edge x-ray absorption spectra of ice is investigated through detailed analysis of the spectral features. The amount of ice defects is found to be minimized on hydrophobic surfaces, such as BaF2(111), with low concentration of nucleation centers. This is manifested through a reduction of the absorption cross-section at 535 eV, which is associated with distorted hydrogen bonds. Furthermore, a connection is made between the observed increase in ...

  17. Application of a relativistic accretion disc model to X-ray spectra of LMC X-1 and GRO J1655-40.

    OpenAIRE

    Gierliński, M.; Maciołek-Niedźwiecki, A.; Ebisawa, K.

    2001-01-01

    We present a general relativistic accretion disc model and its application to the soft-state X-ray spectra of black hole binaries. The model assumes a flat, optically thick disc around a rotating Kerr black hole. The disc locally radiates away the dissipated energy as a blackbody. Special and general relativistic effects influencing photons emitted by the disc are taken into account. The emerging spectrum, as seen by a distant observer, is parametrized by the black hole mass and spin, the acc...

  18. Electronic Raman scattering with excitation between localized states observed in the zinc M{sub 2,3} soft x-ray spectra of ZnS

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, L.; Callcott, T.A.; Jia, J.J. [Univ. of Tennessee, Knoxville, TN (United States)] [and others

    1997-04-01

    Zn M{sub 2,3} soft x-ray fluorescence (SXF) spectra of ZnS and ZnS{sub .5}Se{sub .5} excited near threshold show strong inelastic scattering effects that can be explained using a simple model and an inelastic scattering theory based on second order perturbation theory. This scattering is often called electronic resonance Raman scattering. Tulkki and Aberg have developed this theory in detail for atomic systems, but their treatment can be applied to solid systems by utilizing electronic states characteristic of solids rather than of atomic systems.

  19. Non-linearity issues and multiple ionization satellites in the PIXE portion of spectra from the Mars alpha particle X-ray spectrometer

    Science.gov (United States)

    Campbell, John L.; Heirwegh, Christopher M.; Ganly, Brianna

    2016-09-01

    Spectra from the laboratory and flight versions of the Curiosity rover's alpha particle X-ray spectrometer were fitted with an in-house version of GUPIX, revealing departures from linear behavior of the energy-channel relationships in the low X-ray energy region where alpha particle PIXE is the dominant excitation mechanism. The apparent energy shifts for the lightest elements present were attributed in part to multiple ionization satellites and in part to issues within the detector and/or the pulse processing chain. No specific issue was identified, but the second of these options was considered to be the more probable. Approximate corrections were derived and then applied within the GUAPX code which is designed specifically for quantitative evaluation of APXS spectra. The quality of fit was significantly improved. The peak areas of the light elements Na, Mg, Al and Si were changed by only a few percent in most spectra. The changes for elements with higher atomic number were generally smaller, with a few exceptions. Overall, the percentage peak area changes are much smaller than the overall uncertainties in derived concentrations, which are largely attributable to the effects of rock heterogeneity. The magnitude of the satellite contributions suggests the need to incorporate these routinely in accelerator-based PIXE using helium beams.

  20. Multivariate curve resolution analysis for interpretation of dynamic Cu K-edge X-ray absorption spectroscopy spectra for a Cu doped V(2)O(5) lithium battery.

    Science.gov (United States)

    Conti, Paolo; Zamponi, Silvia; Giorgetti, Marco; Berrettoni, Mario; Smyrl, William H

    2010-05-01

    Vanadium pentoxide materials prepared through sol-gel processes act as excellent intercalation hosts for lithium as well as polyvalent cations. A chemometric approach has been applied to study the X-ray absorption near-edge structure (XANES) evolution during in situ scanning of the Cu(0.1)V(2)O(5) xerogel/Li ions battery. Among the more common techniques, the fixed size windows evolving factor analysis (FSWEFA) permits the number of species involved in the experiment to be determined and the range of existence of each of them. This result, combined with the constraints of the invariance of the total concentration and non-negativity of both concentrations and spectra, enabled us to obtain the spectra of the pure components using a multivariate curve resolution refined by an alternate least squares fitting procedure. This allowed the normalized concentration profile to be understood. This data treatment evidenced the occurrence, for the first time, of three species during the battery charging. This fact finds confirmation by comparison of the pure spectra with the experimental ones. Extended X-ray absorption fine structure (EXAFS) analysis confirms the occurrence of three different chemical environments of Cu during battery charging.

  1. The X-ray spectra of Compton-thick Seyfert 2 galaxies as seen by BeppoSAX

    CERN Document Server

    Matt, G; Guainazzi, M; Iwasawa, K; Bassani, L; Malaguti, G

    2000-01-01

    Results from BeppoSAX observations of Compton--thick Seyfert 2 galaxies are summarized and reviewed, and their general properties derived and discussed. In five out of the seven observed sources, the nucleus is directly visible at high X-ray energies, where the photons penetrate absorbers with column densities in the range 1.1-4.3x10^{24} cm-2 (in the other two sources, NGC 1068 and NGC 7674, the nucleus is instead totally obscured at all energies, implying even larger column densities). In most sources there is unambiguous evidence of a reflection component from optically thick, cold matter, while in two (or maybe four) cases there is also evidence of reflection from ionized matter. For the sources with a measured X-ray luminosity, a comparison with the infrared luminosity is made; while in two cases (the Circinus galaxy and NGC 4945) the IR emission appears to be dominated by starburst activity, in the other three sources (NGC 6240, Mrk 3 and TOL 0109-383) it is likely to be dominated by reprocessing of the...

  2. 1SXPS: A deep Swift X-ray Telescope point source catalog with light curves and spectra

    CERN Document Server

    Evans, P A; Beardmore, A P; Page, K L; Willingale, R; Mountford, C J; Pagani, C; Burrows, D N; Kennea, J A; Perri, M; Tagliaferri, G; Gehrels, N

    2013-01-01

    We present the 1SXPS (Swift-XRT Point Source) catalog of 151,524 X-ray point-sources detected by the Swift-XRT in 8 years of operation. The catalog covers 1905 square degrees distributed approximately uniformly on the sky. We analyze the data in two ways. First we consider all observations individually, for which we have a typical sensitivity of ~3e-13 erg/cm2/s (0.3--10 keV). Then we co-add all data covering the same location on the sky: these images have a typical sensitivity of ~9e-14 erg/cm2/s (0.3--10 keV). Our sky coverage is nearly 2.5 times that of 3XMM-DR4, although the catalog is a factor of ~1.5 less sensitive. The median position error is 5.5" (90% confidence), including systematics. Our source detection method improves on that used in previous XRT catalogs and we report >68,000 new X-ray sources. The goals and observing strategy of the Swift satellite allow us to probe source variability on multiple timescales, and we find ~30,000 variable objects in our catalog. For every source we give position...

  3. Microwave imaging of a solar limb flare - Comparison of spectra and spatial geometry with hard X-rays

    Science.gov (United States)

    Schmahl, E. J.; Kundu, M. R.; Dennis, B. R.

    1985-01-01

    A solar limb flare was mapped using the Very Large Array (VLA) together with hard X-ray (HXR) spectral and spatial observations of the Solar Maximum Mission satellite. Microwave flux records from 2.8 to 19.6 GHz were instrumental in determining the burst spectrum, which has a maximum at 10 GHz. The flux spectrum and area of the burst sources were used to determine the number of electrons producing gyrosynchrotron emission, magnetic field strength, and the energy distribution of gyrosynchrotron-emitting electrons. Applying the thick target model to the HXR spectrum, the number of high energy electrons responsible for the X-ray bursts was found to be 10 to the 36th, and the electron energy distribution was approximately E exp -5, significantly different from the parameters derived from the microwave observations. The HXR imaging observations exhibit some similiarities in size and structure o the first two burst sources mapped with the VLA. However, during the initial burst, the HXR source was single and lower in the corona than the double 6 cm source. The observations are explained in terms of a single loop with an isotropic high-energy electron distribution which produced the microwaves, and a larger beamed component which produced the HXR at the feet of the loop.

  4. Vibrational, X-ray absorption, and Mössbauer spectra of sulfate minerals from the weathered massive sulfide deposit at Iron Mountain, California

    Science.gov (United States)

    Majzlan, Juraj; Alpers, Charles N.; Bender Koch, Christian; McCleskey, R. Blaine; Myneni, Satish B.C.; Neil, John M.

    2011-01-01

    The Iron Mountain Mine Superfund site in California is a prime example of an acid mine drainage (AMD) system with well developed assemblages of sulfate minerals typical for such settings. Here we present and discuss the vibrational (infrared), X-ray absorption, and M??ssbauer spectra of a number of these phases, augmented by spectra of a few synthetic sulfates related to the AMD phases. The minerals and related phases studied in this work are (in order of increasing Fe2O3/FeO): szomolnokite, rozenite, siderotil, halotrichite, r??merite, voltaite, copiapite, monoclinic Fe2(SO4)3, Fe2(SO4)3??5H2O, kornelite, coquimbite, Fe(SO4)(OH), jarosite and rhomboclase. Fourier transform infrared spectra in the region 750-4000cm-1 are presented for all studied phases. Position of the FTIR bands is discussed in terms of the vibrations of sulfate ions, hydroxyl groups, and water molecules. Sulfur K-edge X-ray absorption near-edge structure (XANES) spectra were collected for selected samples. The feature of greatest interest is a series of weak pre-edge peaks whose position is determined by the number of bridging oxygen atoms between Fe3+ octahedra and sulfate tetrahedra. M??ssbauer spectra of selected samples were obtained at room temperature and 80K for ferric minerals jarosite and rhomboclase and mixed ferric-ferrous minerals r??merite, voltaite, and copiapite. Values of Fe2+/[Fe2++Fe3+] determined by M??ssbauer spectroscopy agree well with those determined by wet chemical analysis. The data presented here can be used as standards in spectroscopic work where spectra of well-characterized compounds are required to identify complex mixtures of minerals and related phases. ?? 2011 Elsevier B.V.

  5. Vibrational, X-ray absorption, and Mössbauer spectra of sulfate minerals from the weathered massive sulfide deposit at Iron Mountain, California

    Science.gov (United States)

    Majzlan, Juraj; Alpers, Charles N.; Bender Koch, Christian; McCleskey, R. Blaine; Myneni, Satish B.C.; Neil, John M.

    2014-01-01

    The Iron Mountain Mine Superfund site in California is a prime example of an acid mine drainage (AMD) system with well developed assemblages of sulfate minerals typical for such settings. Here we present and discuss the vibrational (infrared), X-ray absorption, and Mössbauer spectra of a number of these phases, augmented by spectra of a few synthetic sulfates related to the AMD phases. The minerals and related phases studied in this work are (in order of increasing Fe2O3/FeO): szomolnokite, rozenite, siderotil, halotrichite, römerite, voltaite, copiapite, monoclinic Fe2(SO4)3, Fe2(SO4)3·5H2O, kornelite, coquimbite, Fe(SO4)(OH), jarosite and rhomboclase. Fourier transform infrared spectra in the region 750–4000 cm−1 are presented for all studied phases. Position of the FTIR bands is discussed in terms of the vibrations of sulfate ions, hydroxyl groups, and water molecules. Sulfur K-edge X-ray absorption near-edge structure (XANES) spectra were collected for selected samples. The feature of greatest interest is a series of weak pre-edge peaks whose position is determined by the number of bridging oxygen atoms between Fe3+ octahedra and sulfate tetrahedra. Mössbauer spectra of selected samples were obtained at room temperature and 80 K for ferric minerals jarosite and rhomboclase and mixed ferric–ferrous minerals römerite, voltaite, and copiapite. Values of Fe2+/[Fe2+ + Fe3+] determined by Mössbauer spectroscopy agree well with those determined by wet chemical analysis. The data presented here can be used as standards in spectroscopic work where spectra of well-characterized compounds are required to identify complex mixtures of minerals and related phases.

  6. X-ray source development for EXAFS measurements on the National Ignition Facility

    Science.gov (United States)

    Coppari, F.; Thorn, D. B.; Kemp, G. E.; Craxton, R. S.; Garcia, E. M.; Ping, Y.; Eggert, J. H.; Schneider, M. B.

    2017-08-01

    Extended X-ray absorption Fine Structure (EXAFS) measurements require a bright, spectrally smooth, and broad-band x-ray source. In a laser facility, such an x-ray source can be generated by a laser-driven capsule implosion. In order to optimize the x-ray emission, different capsule types and laser irradiations have been tested at the National Ignition Facility (NIF). A crystal spectrometer is used to disperse the x-rays and high efficiency image plate detectors are used to measure the absorption spectra in transmission geometry. EXAFS measurements at the K-edge of iron at ambient conditions have been obtained for the first time on the NIF laser, and the requirements for optimization have been established.

  7. X-ray source development for EXAFS measurements on the National Ignition Facility.

    Science.gov (United States)

    Coppari, F; Thorn, D B; Kemp, G E; Craxton, R S; Garcia, E M; Ping, Y; Eggert, J H; Schneider, M B

    2017-08-01

    Extended X-ray absorption Fine Structure (EXAFS) measurements require a bright, spectrally smooth, and broad-band x-ray source. In a laser facility, such an x-ray source can be generated by a laser-driven capsule implosion. In order to optimize the x-ray emission, different capsule types and laser irradiations have been tested at the National Ignition Facility (NIF). A crystal spectrometer is used to disperse the x-rays and high efficiency image plate detectors are used to measure the absorption spectra in transmission geometry. EXAFS measurements at the K-edge of iron at ambient conditions have been obtained for the first time on the NIF laser, and the requirements for optimization have been established.

  8. Characterizing high energy spectra of NIF ignition Hohlraums using a differentially filtered high energy multipinhole x-ray imager.

    Science.gov (United States)

    Park, Hye-Sook; Dewald, E D; Glenzer, S; Kalantar, D H; Kilkenny, J D; MacGowan, B J; Maddox, B R; Milovich, J L; Prasad, R R; Remington, B A; Robey, H F; Thomas, C A

    2010-10-01

    Understanding hot electron distributions generated inside Hohlraums is important to the national ignition campaign for controlling implosion symmetry and sources of preheat. While direct imaging of hot electrons is difficult, their spatial distribution and spectrum can be deduced by detecting high energy x-rays generated as they interact with target materials. We used an array of 18 pinholes with four independent filter combinations to image entire Hohlraums with a magnification of 0.87× during the Hohlraum energetics campaign on NIF. Comparing our results with Hohlraum simulations indicates that the characteristic 10-40 keV hot electrons are mainly generated from backscattered laser-plasma interactions rather than from Hohlraum hydrodynamics.

  9. Structure and Bonding in Amorphous Cr1-xCx Nanocomposite Thin Films: X-ray Absorption Spectra and First-Principles Calculation

    CERN Document Server

    Olovsson, Weine; Magnuson, Martin

    2016-01-01

    The local structure and chemical bonding in two-phase amorphous Cr$_{1-x}$C$_{x}$ nanocomposite thin films are investigated by Cr $K$-edge ($1s$) X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopies in comparison to theory. By utilizing the computationally efficient \\textit{stochastic quenching} (SQ) technique, we reveal the complexity of different Cr-sites in the transition metal carbides, highlighting the need for large scale averaging to obtain theoretical XANES and EXAFS spectra for comparison with measurements. As shown in this work, it is advantageous to use \\textit{ab initio} theory as an assessment to correctly model and fit experimental spectra and investigate the trends of bond lengths and coordination numbers in complex amorphous materials. With sufficient total carbon content ($\\geq$ 30 at\\%), we find that the short-range coordination in the amorphous carbide phase exhibit similarities to that of a Cr$_{7}$C$_{3\\pm{}y}$ structure, while e...

  10. Monte Carlo calculation of ion, electron, and photon spectra of xenon atoms in x-ray free-electron laser pulses

    CERN Document Server

    Son, Sang-Kil; 10.1103/PhysRevA.85.063415

    2013-01-01

    When atoms and molecules are irradiated by an x-ray free-electron laser (XFEL), they are highly ionized via a sequence of one-photon ionization and relaxation processes. To describe the ionization dynamics during XFEL pulses, a rate equation model has been employed. Even though this model is straightforward for the case of light atoms, it generates a huge number of coupled rate equations for heavy atoms like xenon, which are not trivial to solve directly. Here, we employ the Monte Carlo method to address this problem and we investigate ionization dynamics of xenon atoms induced by XFEL pulses at a photon energy of 4500 eV. Charge state distributions, photo-/Auger electron spectra, and fluorescence spectra are presented for x-ray fluences of up to $10^{13}$ photons/$\\mu$m$^2$. With the photon energy of 4500 eV, xenon atoms can be ionized up to +44 through multiphoton absorption characterized by sequential one-photon single-electron interactions.

  11. Study of X-Ray and $\\gamma$-Ray Spectra from Antiprotonic Atoms at the Slowly Extracted Antiproton Beam of LEAR

    CERN Multimedia

    2002-01-01

    This experiment will study the X-ray spectra of antiprotonic atoms and the $\\gamma$ spectra of residual nuclei after the antiproton absorption. We intend to begin with measurements on selected isotopically pure targets. Strong interaction effects, the antiproton absorption and the atomic cascade are analysed through the measurement of energies, lineshapes, relative and absolute intensities of all observable lines. The experiments are continued to determine st in resolved fine structure levels and in different isotopes of the same element. Coincidence techniques may be applied. All components of the experimental set-up are already existing from previous experiments and we could begin the measurements with any slowly extracted beam of low energy at LEAR.

  12. The Be K-edge in beryllium oxide and chalcogenides: soft x-ray absorption spectra from first-principles theory and experiment.

    Science.gov (United States)

    Olovsson, W; Weinhardt, L; Fuchs, O; Tanaka, I; Puschnig, P; Umbach, E; Heske, C; Draxl, C

    2013-08-07

    We have carried out a theoretical and experimental investigation of the beryllium K-edge soft x-ray absorption fine structure of beryllium compounds in the oxygen group, considering BeO, BeS, BeSe, and BeTe. Theoretical spectra are obtained ab initio, through many-body perturbation theory, by solving the Bethe-Salpeter equation (BSE), and by supercell calculations using the core-hole approximation. All calculations are performed with the full-potential linearized augmented plane-wave method. It is found that the two different theoretical approaches produce a similar fine structure, in good agreement with the experimental data. Using the BSE results, we interpret the spectra, distinguishing between bound core-excitons and higher energy excitations.

  13. Conformational studies of 3-[(2,2-dimethylhydrazinyl)methylene]-pentane-2,4-dione using vibrational and NMR spectra, X-ray analysis and ab initio calculations

    Science.gov (United States)

    Gatial, Anton; Herich, Peter; Tarabová, Denisa; Milata, Viktor; Prónayová, Nadežda

    2017-07-01

    The conformers of push-pull 3-[(2,2-dimethylhydrazinyl)methylene]-pentane-2,4-dione (CH3)2Nsbnd NHsbnd CHdbnd C(COCH3)2 (DMHMP) have been studied experimentally by NMR and vibrational spectroscopy and theoretically by ab initio calculations at MP2 and DFT B3LYP levels in various basis sets. The NMR spectra were obtained in chloroform and dimethylsulfoxide and the IR and Raman spectra of DMHMP as a solid and as a solute in various less and more polar solvents at room temperature have been recorded. DMHMP was prepared as a pure solid and the data from X-ray analysis revealed that DMHMP exists in solid state as EZa conformer with an intramolecular hydrogen bond. The geometries and relative energies of possible conformers of DMHMP were evaluated at the both levels of theory in several basis sets and compared with the data from X-ray analysis. According to the NMR spectra the studied compound exists as a single entity. On the other hand vibrational spectra revealed that in less polar DMHMP solutions the presence of the second less polar ZZa conformer is possible, whereas in more polar solvent only one EZa conformer is observed. The influence of the environment polarity on this conformational equilibrium is discussed with respect to the SCRF solvent effect calculations using IEFPCM model. The observed IR and Raman bands were compared with calculated MP2/cc-pVTZ harmonic vibrational frequencies and assigned on the basis of potential energy distribution.

  14. Chest X Ray?

    Science.gov (United States)

    ... this page from the NHLBI on Twitter. Chest X Ray A chest x ray is a fast and painless imaging test ... tissue scarring, called fibrosis. Doctors may use chest x rays to see how well certain treatments are ...

  15. X-Rays

    Science.gov (United States)

    X-rays are a type of radiation called electromagnetic waves. X-ray imaging creates pictures of the inside of ... different amounts of radiation. Calcium in bones absorbs x-rays the most, so bones look white. Fat ...

  16. Medical X-Rays

    Science.gov (United States)

    ... Benefits The discovery of X-rays and the invention of CT represented major advances in medicine. X- ... in X-ray and CT Examinations — X-ray definition, dose measurement, safety precautions, risk, and consideration with ...

  17. ON ESTIMATING THE HIGH-ENERGY CUTOFF IN THE X-RAY SPECTRA OF BLACK HOLES VIA REFLECTION SPECTROSCOPY

    Energy Technology Data Exchange (ETDEWEB)

    García, Javier A.; Steiner, James F.; McClintock, Jeffrey E.; Keck, Mason L. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Dauser, Thomas; Wilms, Jörn, E-mail: javier@head.cfa.harvard.edu, E-mail: jem@cfa.harvard.edu, E-mail: jsteiner@head.cfa.harvard.edu, E-mail: keckm@bu.edu, E-mail: thomas.dauser@sternwarte.uni-erlangen.de [Dr. Karl Remeis-Observatory and Erlangen Centre for Astroparticle Physics, Sternwartstr. 7, D-96049 Bamberg (Germany)

    2015-08-01

    The fundamental parameters describing the coronal spectrum of an accreting black hole are the slope Γ of the power-law continuum and the energy E{sub cut} at which it rolls over. Remarkably, this latter parameter can be accurately measured for values as high as 1 MeV by modeling the spectrum of X-rays reflected from a black hole accretion disk at energies below 100 keV. This is possible because the details in the reflection spectrum, rich in fluorescent lines and other atomic features, are very sensitive to the spectral shape of the hardest coronal radiation illuminating the disk. We show that by fitting simultaneous NuSTAR (3–79 keV) and low-energy (e.g., Suzaku) data with the most recent version of our reflection model relxill one can obtain reasonable constraints on E{sub cut} at energies from tens of keV up to 1 MeV, for a source as faint as 1 mCrab in a 100 ks observation.

  18. Energy spectra of X-ray quasi-periodic oscillations in the Lense-Thirring precession model

    CERN Document Server

    Zycki, Piotr T; Ingram, Adam

    2016-01-01

    We model the energy dependence of a quasi periodic oscillation (QPOs) produced by Lense-Thirring precession of a hot inner flow. We use a fully 3-dimensional Monte-Carlo code to compute the Compton scattered flux produced by the hot inner flow intercepting seed photons from an outer truncated standard disc. The changing orientation of the precessing torus relative to the line of sight produces the observed modulation of the X-ray flux. We consider two scenarios of precession. First, we assume that the precession axis is perpendicular to the plane of the outer disc. In this scenario the relative geometry of the cold disc and the hot torus does not change during precession, so the emitted spectrum does not change, and the modulation is solely due to the changing viewing angle. In the second scenario the precession axis is tilted with respect to the outer disc plane. This leads to changes in the relative geometry of the hot flow and cold plasma, possibly resulting in variations of the plasma temperature and thus...

  19. Wavelengths, oscillator strengths and radiative transition rates for K{alpha} lines in titanium x-ray spectra

    Energy Technology Data Exchange (ETDEWEB)

    Hu Feng; Wang Chuangke; Zhao Xuefeng [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Yang Jiamin; Jiang Gang, E-mail: yjm70018@my-public.sc.cninfo.net [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610064 (China)

    2011-06-15

    The oscillator strengths, line strengths and wavelengths are presented for all 1s-2p transitions in titanium ions. X-ray emission from titanium is extensively used, for example for diagnosis, in fusion experiments. The K{alpha} 1s-2p transitions are limited to transitions from helium-like to fluorine-like ion as the 2p subshell is filled beyond fluorine. While there are two 1s-2p transitions (1s{sup 2}S{sub 1/2}-2p{sup 2}P{sub 1/2} and 1s{sup 2}S{sub 1/2}-2p{sup 2}P{sub 3/2}) for hydrogen-like titanium, Ti{sup 20+}, the number varies depending on the number of electrons in the 2p subshell before and after the transition. For example, there are 35 1s-2p transitions giving the same number of K{alpha} lines for carbon-like titanium, Ti{sup 16+}. The present results are obtained from configuration interaction atomic structure calculations using the code GRASPVU, which includes relativistic effects in the Dirac-Fock approximation. The results have been benchmarked for a few ionic states. A comparison of our results with the very few transitions in the literature as well as those from other codes shows reasonable accuracy of the present results.

  20. On Estimating the High-Energy Cutoff in the X-ray Spectra of Black Holes via Reflection Spectroscopy

    CERN Document Server

    Garcia, Javier A; Steiner, James F; McClintock, Jeffrey E; Keck, Mason L; Wilms, Joern

    2015-01-01

    The fundamental parameters describing the coronal spectrum of an accreting black hole are the slope $\\Gamma$ of the power-law continuum and the energy $E_{cut}$ at which it rolls over. Remarkably, this parameter can be accurately measured for values as high as 1 MeV by modeling the spectrum of X-rays reflected from a black hole accretion disk at energies below 100 keV. This is possible because the details in the reflection spectrum, rich in fluorescent lines and other atomic features, are very sensitive to the spectral shape of the hardest coronal radiation illuminating the disk. We show that fitting simultaneous NuSTAR (3-79 keV) and low-energy (e.g., Suzaku) data with the most recent version of our reflection model RELXILL, one can obtain reasonable constraints on $E_{cut}$ at energies from tens of keV up to 1 MeV, for a source as faint as 1 mCrab in a 100 ks observation.

  1. Nitrogen K-edge X-ray absorption near edge structure (XANES) spectra of purine-containing nucleotides in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Hiroyuki; Fukao, Taishi; Minami, Hirotake; Ukai, Masatoshi [Department of Applied Physics, Tokyo University of Agriculture and Technology, Koganei-shi, Tokyo 184-8588 (Japan); Fujii, Kentaro; Yokoya, Akinari [Advanced Science Research Center, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Fukuda, Yoshihiro; Saitoh, Yuji [Synchrotron Radiation Research Center, Japan Atomic Energy Agency, Sayo-gun, Hyougo 679-5148 (Japan)

    2014-08-07

    The N K-edge X-ray absorption near edge structure (XANES) spectra of the purine-containing nucleotide, guanosine 5{sup ′}-monophosphate (GMP), in aqueous solution are measured under various pH conditions. The spectra show characteristic peaks, which originate from resonant excitations of N 1s electrons to π* orbitals inside the guanine moiety of GMP. The relative intensities of these peaks depend on the pH values of the solution. The pH dependence is explained by the core-level shift of N atoms at specific sites caused by protonation and deprotonation. The experimental spectra are compared with theoretical spectra calculated by using density functional theory for GMP and the other purine-containing nucleotides, adenosine 5{sup ′}-monophosphate, and adenosine 5{sup ′}-triphosphate. The N K-edge XANES spectra for all of these nucleotides are classified by the numbers of N atoms with particular chemical bonding characteristics in the purine moiety.

  2. Experimental study of the X-ray spectra optimization for computed radiography mammography systems; Investigacao experimental da otimizacao do espectro de raios X em sistemas de mamografia computadorizada

    Energy Technology Data Exchange (ETDEWEB)

    Tomal, Alessandra, E-mail: atomal@ifi.unicamp.br [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Instituto de Fisica Gleb Wataghin; Cunha, Diego M. [Universidade Federal de Uberlandia (UFU), Uberlandia, MG (Brazil). Instituto de Fisica; Nogueira, Maria S. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Gaspar, Fabio [Vigilancia Sanitaria, Campinas, SP (Brazil); Poletti, Martin E. [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Departamento de Fisica

    2013-12-15

    Digital mammography is replacing screen-film mammography due to several advantages of digital receptors. The use of Computed Radiography (CR) mammography systems has been considered an alternative to achieve digital images with a low cost. Besides, the optimization of the X-ray spectrum, characterized by the anode/filter combination and tube potential, is an important step in order to improve the image quality with the lower dose to the breast. In this work, we investigated the optimal X-ray spectra using a figure of merit for two mammography equipment: Senographe DMR (General Electric Medical Systems) and Mammomat 3000 Nova (Siemens), both using an image plate Kodak EHR-M2 (Kodak DirectView). A PMMA phantom, simulating breast with thicknesses of 5 cm, was used. The anode/filter combinations evaluated were: Mo/Mo, Mo/Rh, Rh/Rh and Rh/Al for the Senographe system, and Mo/Mo, Mo/Rh, W/Rh for the Mammomat system, for all the intervals of tube potential range from 24 to 35 kVp. Results demonstrate that the higher values of FOM were achieved with the Rh/Rh at 29 kVp and Rh/Al at 26 kVp for the Senographe system, and for the W/Rh at 28 kVp in the Mammomat one. The reduction in the dose associated with the optimum spectra was 13 and 26% for the Senographe and Mammomat systems, respectively. Finally, our results suggest that anode/filter combinations of more energetic spectra than the standard Mo/Mo combination are recommended for thicker breast, in order to reduce the breast dose levels. (author)

  3. Single impurity Anderson model versus density functional theory for describing Ce L3 x-ray absorption spectra of CeFe2: resolution of a recent controversy.

    Science.gov (United States)

    Kotani, A; Kvashnina, K O; Glatzel, P; Parlebas, J C; Schmerber, G

    2012-01-20

    We resolved a recent controversy on the structure of the Ce L(3) x-ray absorption spectra (XAS) of CeFe(2); i.e., which of the single impurity Anderson model (SIAM) and the first-principles band calculations based on the density-functional theory (DFT) describes more appropriately the Ce 4f states and their contribution to the Ce L(3) XAS? For this purpose, we examined the core-hole effect in Ce L(3) XAS as an application of our new method taking advantage of resonant x-ray emission spectroscopy. Our result clearly shows that the Ce L(3) XAS structure is caused by the mixed valence 4f character revealed by the core-hole potential effect as indicated by SIAM, but denies the possibility that the L(3) XAS structure is caused by the 5d band structure with a very small core-hole effect as predicted by band calculations based on DFT. © 2012 American Physical Society

  4. Active Region Soft X-Ray Spectra as Observed Using Sounding Rocket Measurements from the Solar Aspect Monitor (SAM), - a Modified SDO/EVE Instrument

    Science.gov (United States)

    Wieman, S. R.; Didkovsky, L. V.; Woods, T. N.; Jones, A. R.; Caspi, A.; Warren, H. P.

    2015-12-01

    Observations of solar active regions (ARs) in the soft x-ray spectral range (0.5 to 3.0 nm) were made on sounding rocket flight NASA 36.290 using a modified Solar Aspect Monitor (SAM), a pinhole camera on the EUV Variability Experiment (EVE) sounding rocket instrument. The suite of EVE rocket instruments is designed for under-flight calibrations of the orbital EVE on SDO. While the sounding rocket EVE instrument is for the most part a duplicate of the EVE on SDO, the SAM channel on the rocket version was modified in 2012 to include a free-standing transmission grating so that it could provide spectrally resolved images of the solar disk with the best signal to noise ratio for the brightest features on it, such as ARs. Calibrations of the EVE sounding rocket instrument at the National Institute of Standards and Technology Synchrotron Ultraviolet Radiation Facility (NIST SURF) have provided a measurement of the SAM absolute spectral response function and a mapping of wavelength separation in the grating diffraction pattern. For solar observations, this spectral separation is on a similar scale to the spatial size of the AR on the CCD, so dispersed AR images associated with emission lines of similar wavelength tend to overlap. Furthermore, SAM shares a CCD detector with MEGS-A, a separate EVE spectrometer channel, and artifacts of the MEGS-A signal (a set of bright spectral lines) appear in the SAM images. For these reasons some processing and analysis of the solar images obtained by SAM must be performed in order to determine spectra of the observed ARs. We present a method for determining AR spectra from the SAM rocket images and report initial soft X-ray spectra for two of the major active regions (AR11877 and AR11875) observed on flight 36.290 on 21 October 2013 at about 18:30 UT. We also compare our results with concurrent measurements from other solar soft x-ray instrumentation.

  5. Broadband turbulent spectra in gamma-ray burst light curves

    Energy Technology Data Exchange (ETDEWEB)

    Van Putten, Maurice H. P. M. [Astronomy and Space Science, Sejong University, 98 Gunja-Dong Gwangin-gu, Seoul 143-747 (Korea, Republic of); Guidorzi, Cristiano; Frontera, Filippo, E-mail: mvp@sejong.ac.kr [Department of Physics and Earth Sciences, University of Ferrara, Via Saragat 1, I-44122 Ferrara (Italy)

    2014-05-10

    Broadband power density spectra offer a window to understanding turbulent behavior in the emission mechanism and, at the highest frequencies, in the putative inner engines powering long gamma-ray bursts (GRBs). We describe a chirp search method alongside Fourier analysis for signal detection in the Poisson noise-dominated, 2 kHz sampled, BeppoSAX light curves. An efficient numerical implementation is described in O(Nnlog n) operations, where N is the number of chirp templates and n is the length of the light-curve time series, suited for embarrassingly parallel processing. For the detection of individual chirps over a 1 s duration, the method is one order of magnitude more sensitive in signal-to-noise ratio than Fourier analysis. The Fourier-chirp spectra of GRB 010408 and GRB 970816 show a continuation of the spectral slope with up to 1 kHz of turbulence identified in low-frequency Fourier analysis. The same continuation is observed in an average spectrum of 42 bright, long GRBs. An outlook on a similar analysis of upcoming gravitational wave data is included.

  6. A new Monte Carlo code for simulation of the effect of irregular surfaces on X-ray spectra

    Energy Technology Data Exchange (ETDEWEB)

    Brunetti, Antonio, E-mail: brunetti@uniss.it; Golosio, Bruno

    2014-04-01

    Generally, quantitative X-ray fluorescence (XRF) analysis estimates the content of chemical elements in a sample based on the areas of the fluorescence peaks in the energy spectrum. Besides the concentration of the elements, the peak areas depend also on the geometrical conditions. In fact, the estimate of the peak areas is simple if the sample surface is smooth and if the spectrum shows a good statistic (large-area peaks). For this reason often the sample is prepared as a pellet. However, this approach is not always feasible, for instance when cultural heritage or valuable samples must be analyzed. In this case, the sample surface cannot be smoothed. In order to address this problem, several works have been reported in the literature, based on experimental measurements on a few sets of specific samples or on Monte Carlo simulations. The results obtained with the first approach are limited by the specific class of samples analyzed, while the second approach cannot be applied to arbitrarily irregular surfaces. The present work describes a more general analysis tool based on a new fast Monte Carlo algorithm, which is virtually able to simulate any kind of surface. At the best of our knowledge, it is the first Monte Carlo code with this option. A study of the influence of surface irregularities on the measured spectrum is performed and some results reported. - Highlights: • We present a fast Monte Carlo code with the possibility to simulate any irregularly rough surfaces. • We show applications to multilayer measurements. • Real time simulations are available.

  7. Computer-aided screening system for cervical precancerous cells based on field emission scanning electron microscopy and energy dispersive x-ray images and spectra

    Science.gov (United States)

    Jusman, Yessi; Ng, Siew-Cheok; Hasikin, Khairunnisa; Kurnia, Rahmadi; Osman, Noor Azuan Bin Abu; Teoh, Kean Hooi

    2016-10-01

    The capability of field emission scanning electron microscopy and energy dispersive x-ray spectroscopy (FE-SEM/EDX) to scan material structures at the microlevel and characterize the material with its elemental properties has inspired this research, which has developed an FE-SEM/EDX-based cervical cancer screening system. The developed computer-aided screening system consisted of two parts, which were the automatic features of extraction and classification. For the automatic features extraction algorithm, the image and spectra of cervical cells features extraction algorithm for extracting the discriminant features of FE-SEM/EDX data was introduced. The system automatically extracted two types of features based on FE-SEM/EDX images and FE-SEM/EDX spectra. Textural features were extracted from the FE-SEM/EDX image using a gray level co-occurrence matrix technique, while the FE-SEM/EDX spectra features were calculated based on peak heights and corrected area under the peaks using an algorithm. A discriminant analysis technique was employed to predict the cervical precancerous stage into three classes: normal, low-grade intraepithelial squamous lesion (LSIL), and high-grade intraepithelial squamous lesion (HSIL). The capability of the developed screening system was tested using 700 FE-SEM/EDX spectra (300 normal, 200 LSIL, and 200 HSIL cases). The accuracy, sensitivity, and specificity performances were 98.2%, 99.0%, and 98.0%, respectively.

  8. Measurement of helium-like and hydrogen-like argon spectra using double-crystal X-ray spectrometers on EAST

    Science.gov (United States)

    Lyu, B.; Chen, J.; Hu, R. J.; Wang, F. D.; Li, Y. Y.; Fu, J.; Shen, Y. C.; Bitter, M.; Hill, K. W.; Delgado-Aparicio, L. F.; Pablant, N.; Lee, S. G.; Ye, M. Y.; Shi, Y. J.; Wan, B. N.

    2016-11-01

    A two-crystal assembly was deployed on the tangential X-ray crystal spectrometer to measure both helium-like and hydrogen-like spectra on EAST. High-quality helium-like and hydrogen-like spectra were observed simultaneously for the first time on one detector for a wide range of plasma parameters. Profiles of line-integrated core ion temperatures inferred from two spectra were consistent. Since tungsten was adopted as the upper divertor material, one tungsten line (W XLIV at 4.017 Å) on the short-wavelength side of the Lyman-α line (Lα1) was identified for typical USN discharges, which was diffracted by a He-like crystal (2d = 4.913 Å). Another possible Fe XXV line (1.85 Å) was observed to be located on the long-wavelength side of resonance line (w), which was diffracted from a H-like crystal (2d = 4.5622 Å) on the second order. Be-like argon lines were also observable that fill the detector space between the He-like and H-like spectra.

  9. X-rays and gamma-rays from accretion flows onto black holes in Seyferts and X-ray binaries

    Science.gov (United States)

    Zdziarski, Andrzej A.; Johnson, W. Neil; Poutanen, Juri; Magdziarz, Pawel; Gierlinski, Marek

    1997-01-01

    Observations and theoretical models of X-ray/gamma ray spectra of radio quiet Seyfert galaxies and Galactic black hole candidates are reviewed. The spectra from these objects share the following characteristics: an underlying power law with a high energy cutoff above 200 keV; a Compton reflection component with a Fe K alpha line, and a low energy absorption by intervening cold matter. The X-ray energy spectral index, alpha, is typically in the range between 0.8 and 1 in Seyfert spectra, and that of the hard state spectra of the black hole candidates Cygnus X-1 and GX 339-4 is typically between 0.6 and 0.8. The Compton reflection component corresponds with cold matter covering a solid angle of between 0.8pi and 2pi as seen from the X-ray source. The broadband spectra of both classes of sources are well fitted by Compton upscattering of soft photons in thermal plasma. The fits yield a thermal plasma temperature of 100 keV and the Thomson optical depth of 1. All the spectra presented are cut off before the electron rest energy 511 keV, indicating that electron/positron pair production is an important process.

  10. Assignment of Pre-Edge Features in the Ru K-Edge X-Ray Absorption Spectra of Organometallic Ruthenium Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Getty, K.; Delgado-Jaime, M.U.; Kennepohl, P.

    2009-05-18

    The nature of the lowest energy bound-state transition in the Ru K-edge X-ray absorption spectra for a series of Grubbs-type ruthenium complexes was investigated. The pre-edge feature was unambiguously assigned as resulting from formally electric dipole forbidden Ru 4d {l_arrow} 1s transitions. The intensities of these transitions are extremely sensitive to the ligand environment and the symmetry of the metal centre. In centrosymmetric complexes the pre-edge is very weak since it is limited by the weak electric quadrupole intensity mechanism. By contrast, upon breaking centrosymmetry, Ru 5p-4d mixing allows for introduction of electric dipole allowed character resulting in a dramatic increase in the pre-edge intensity. The information content of this approach is explored as it relates to complexes of importance in olefin metathesis and its relevance as a tool for the study of reactive intermediates.

  11. Gravitationally Redshifted Absorption Lines in the Burst Spectra of the Neutron Star in the X-Ray Binary EXO 0748-676

    Science.gov (United States)

    Cottoam, J.; Paerels, F.; Mendez, M.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    The most straightforward manner of determining masses and radii of neutron stars is by measuring the gravitational redshift of spectral lines produced in the neutron star photosphere; such a measurement would provide direct constraints on the mass-to-radius ratio of the neutron star, and therefore on the equation of state for neutron star matter. Using data taken with the Reflection Grating Spectrometer on board the XMM-Newton observatory we identify, for the first time, significant absorption lines in the spectra of 28 bursts of the low-mass X-ray binary EXO 0748-676. The most significant features are consistent with the Fe XXVI and XXV n=2-3 and O VIII n=1-2 transitions, with a redshift of z=0.35, identical within small uncertainties for the different transitions. This constitutes the first direct and unambiguous measurement of the gravitational redshift in a neutron star.

  12. X-ray Spectroscopy of Cooling Cluster

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, J.R.; /SLAC; Fabian, A.C.; /Cambridge U., Inst. of Astron.

    2006-01-17

    We review the X-ray spectra of the cores of clusters of galaxies. Recent high resolution X-ray spectroscopic observations have demonstrated a severe deficit of emission at the lowest X-ray temperatures as compared to that expected from simple radiative cooling models. The same observations have provided compelling evidence that the gas in the cores is cooling below half the maximum temperature. We review these results, discuss physical models of cooling clusters, and describe the X-ray instrumentation and analysis techniques used to make these observations. We discuss several viable mechanisms designed to cancel or distort the expected process of X-ray cluster cooling.

  13. Hard X-ray Spectroscopy of Obscured AGN with NuSTAR

    Science.gov (United States)

    Balokovic, Mislav; Harrison, Fiona; NuSTAR Extragalactic Surveys Team

    2017-01-01

    The Nuclear Spectroscopic Telescope Array (NuSTAR) has enabled studies of the local active galactic nuclei (AGN) to extend into the hard X-ray band, up to 79 keV, with unprecedented spatial resolution and sensitivity. As a part of its extragalactic program, NuSTAR is surveying the nearby population of AGN detected at hard X-ray energies by the Swift Burst Alert Telescope (Swift/BAT), selecting even the most obscured local AGN. I will highlight some of the results based on broadband X-ray spectroscopy of individual targets and present my work on the large representative sample of more than a hundred nearby obscured AGN, which constitutes the largest available atlas of hard X-ray spectra of obscured AGN to date. The high quality of the data allows us to probe the details of AGN structures such as the X-ray-emitting corona and the toroidal obscurer in the under-explored spectral window above 10 keV. I will present both phenomenological results important for synthesis models of the cosmic X-ray background, and a novel approach for constraining the geometry of the gas surrounding the supermassive black hole (including the accretion disk, the broad-line region, and the torus) from the hard X-ray band. Finally, I will discuss how what we learned from this survey of local AGN relates to deeper high-redshift X-ray surveys and AGN structure probes at other wavelengths.

  14. Sounding Rocket Observations of Active Region Soft X-Ray Spectra Between 0.5 and 2.5 nm Using a Modified SDO/EVE Instrument

    Science.gov (United States)

    Wieman, Seth; Didkovsky, Leonid; Woods, Thomas; Jones, Andrew; Moore, Christopher

    2016-12-01

    Spectrally resolved measurements of individual solar active regions (ARs) in the soft X-ray (SXR) range are important for studying dynamic processes in the solar corona and their associated effects on the Earth's upper atmosphere. They are also a means of evaluating atomic data and elemental abundances used in physics-based solar spectral models. However, very few such measurements are available. We present spectral measurements of two individual ARs in the 0.5 to 2.5 nm range obtained on the NASA 36.290 sounding rocket flight of 21 October 2013 (at about 18:30 UT) using the Solar Aspect Monitor (SAM), a channel of the Extreme Ultaviolet Variability Experiment (EVE) payload designed for underflight calibrations of the orbital EVE on the Solar Dynamics Observatory (SDO). The EVE rocket instrument is a duplicate of the EVE on SDO, except the SAM channel on the rocket version was modified in 2012 to include a freestanding transmission grating to provide spectrally resolved images of the solar disk with the best signal to noise ratio for the brightest features, such as ARs. Calibrations of the EVE sounding rocket instrument at the National Institute of Standards and Technology Synchrotron Ultraviolet Radiation Facility (NIST/SURF) have provided a measurement of the SAM absolute spectral response function and a mapping of wavelength separation in the grating diffraction pattern. We discuss techniques (incorporating the NIST/SURF data) for determining SXR spectra from the dispersed AR images as well as the resulting spectra for NOAA ARs 11877 and 11875 observed on the 2013 rocket flight. In comparisons with physics-based spectral models using the CHIANTI v8 atomic database we find that both AR spectra are in good agreement with isothermal spectra (4 MK), as well as spectra based on an AR differential emission measure (DEM) included with the CHIANTI distribution, with the exception of the relative intensities of strong Fe xvii lines associated with 2p6-2p53{s} and 2p6-2p

  15. NuSTAR Hard X-ray Survey of the Galactic Center Region. I. Hard X-ray Morphology and Spectroscopy of the Diffuse Emission

    DEFF Research Database (Denmark)

    Mori, Kaya; Hailey, Charles J.; Krivonos, Roman

    2015-01-01

    pulsar wind nebulae (PWNe). NuSTAR detects non-thermal X-ray continuum emission spatially correlated with the 6.4 keV Fe K alpha fluorescence line emission associated with two Sgr A molecular clouds: MC1 and the Bridge. Broadband X-ray spectral analysis with a Monte-Carlo based X-ray reflection model......We present the first sub-arcminute images of the Galactic Center above 10 keV, obtained with NuSTAR. NuSTAR resolves the hard X-ray source IGR J17456-2901 into non-thermal X-ray filaments, molecular clouds, point sources, and a previously unknown central component of hard X-ray emission (CHXE). Nu......STAR detects four non-thermal X-ray filaments, extending the detection of their power-law spectra with Gamma similar to 1.3-2.3 up to similar to 50 keV. A morphological and spectral study of the filaments suggests that their origin may be heterogeneous, where previous studies suggested a common origin in young...

  16. X-ray Echo Spectroscopy

    Science.gov (United States)

    Shvyd'ko, Yuri

    2016-02-01

    X-ray echo spectroscopy, a counterpart of neutron spin echo, is being introduced here to overcome limitations in spectral resolution and weak signals of the traditional inelastic x-ray scattering (IXS) probes. An image of a pointlike x-ray source is defocused by a dispersing system comprised of asymmetrically cut specially arranged Bragg diffracting crystals. The defocused image is refocused into a point (echo) in a time-reversal dispersing system. If the defocused beam is inelastically scattered from a sample, the echo signal acquires a spatial distribution, which is a map of the inelastic scattering spectrum. The spectral resolution of the echo spectroscopy does not rely on the monochromaticity of the x rays, ensuring strong signals along with a very high spectral resolution. Particular schemes of x-ray echo spectrometers for 0.1-0.02 meV ultrahigh-resolution IXS applications (resolving power >108 ) with broadband ≃5 - 13 meV dispersing systems are introduced featuring more than 103 signal enhancement. The technique is general, applicable in different photon frequency domains.

  17. X-ray echo spectroscopy

    CERN Document Server

    Shvyd'ko, Yuri

    2015-01-01

    X-ray echo spectroscopy, a counterpart of neutron spin-echo, is being introduced here to overcome limitations in spectral resolution and weak signals of the traditional inelastic x-ray scattering (IXS) probes. An image of a point-like x-ray source is defocused by a dispersing system comprised of asymmetrically cut specially arranged Bragg diffracting crystals. The defocused image is refocused into a point (echo) in a time-reversal dispersing system. If the defocused beam is inelastically scattered from a sample, the echo signal acquires a spatial distribution, which is a map of the inelastic scattering spectrum. The spectral resolution of the echo spectroscopy does not rely on the monochromaticity of the x-rays, ensuring strong signals along with a very high spectral resolution. Particular schemes of x-ray echo spectrometers for 0.1--0.02-meV ultra-high-resolution IXS applications (resolving power $> 10^8$) with broadband $\\simeq$~5--13~meV dispersing systems are introduced featuring more than $10^3$ signal e...

  18. X-ray Echo Spectroscopy.

    Science.gov (United States)

    Shvyd'ko, Yuri

    2016-02-26

    X-ray echo spectroscopy, a counterpart of neutron spin echo, is being introduced here to overcome limitations in spectral resolution and weak signals of the traditional inelastic x-ray scattering (IXS) probes. An image of a pointlike x-ray source is defocused by a dispersing system comprised of asymmetrically cut specially arranged Bragg diffracting crystals. The defocused image is refocused into a point (echo) in a time-reversal dispersing system. If the defocused beam is inelastically scattered from a sample, the echo signal acquires a spatial distribution, which is a map of the inelastic scattering spectrum. The spectral resolution of the echo spectroscopy does not rely on the monochromaticity of the x rays, ensuring strong signals along with a very high spectral resolution. Particular schemes of x-ray echo spectrometers for 0.1-0.02 meV ultrahigh-resolution IXS applications (resolving power >10^{8}) with broadband ≃5-13  meV dispersing systems are introduced featuring more than 10^{3} signal enhancement. The technique is general, applicable in different photon frequency domains.

  19. Characterizing X-Ray and Radio Emission in the Black Hole X-Ray Binary V404 Cygni During Quiescence

    DEFF Research Database (Denmark)

    Rana, Vikram; Loh, Alan; Corbel, Stephane

    2016-01-01

    We present results from multi-wavelength simultaneous X-ray and radio observations of the black hole X-ray binary V404 Cyg in quiescence. Our coverage with NuSTAR provides the very first opportunity to study the X-ray spectrum of V404 Cyg at energies above 10 keV. The unabsorbed broadband (0.3–30...

  20. Characterizing X-Ray and Radio Emission in the Black Hole X-Ray Binary V404 Cygni During Quiescence

    DEFF Research Database (Denmark)

    Rana, Vikram; Loh, Alan; Corbel, Stephane

    2016-01-01

    We present results from multi-wavelength simultaneous X-ray and radio observations of the black hole X-ray binary V404 Cyg in quiescence. Our coverage with NuSTAR provides the very first opportunity to study the X-ray spectrum of V404 Cyg at energies above 10 keV. The unabsorbed broadband (0...

  1. The ultraluminous x-ray sources ngc 1313 x-1 and x-2: a broadband study with NuSTAR and XMM-Newton

    DEFF Research Database (Denmark)

    Bachetti, Matteo; Rana, Vikram; Walton, Dominic J.;

    2013-01-01

    We present the results of NuSTAR and XMM-Newton observations of the two ultraluminous X-ray sources: NGC 1313 X-1 and X-2. The combined spectral bandpass of the two satellites enables us to produce the first spectrum of X-1 between 0.3 and 30 keV, while X-2 is not significantly detected by NuSTAR...

  2. Phonon density of states of Sn in textured SnO under high pressure: Comparison of nuclear inelastic x-ray scattering spectra to a shell model

    Science.gov (United States)

    Giefers, H.; Koval, S.; Wortmann, G.; Sturhahn, W.; Alp, E. E.; Hu, M. Y.

    2006-09-01

    The local phonon density of states (DOS) at the Sn site in tin monoxide (SnO) is studied at pressures up to 8GPa with Sn119 nuclear resonant inelastic x-ray scattering (NRIXS) of synchrotron radiation at 23.88keV . The preferred orientation (texture) of the SnO crystallites in the investigated samples is used to measure NRIXS spectra preferentially parallel and almost perpendicular to the c axis of tetragonal SnO . A subtraction method is applied to these NRIXS spectra to produce projected local Sn DOS spectra as seen parallel and perpendicular to the c axis of SnO . These experimentally obtained local Sn DOS spectra, both in the polycrystalline case as well as projected parallel and perpendicular to the c axis, are compared with corresponding theoretical phonon DOS spectra, derived from dispersion relations calculated with a recently developed shell model. Comparison between the experimental projected Sn DOS spectra and the corresponding theoretical DOS spectra enables us to follow the pressure-induced shifts of several acoustic and optic phonon modes. While the principal spectral features of the experimental and theoretical phonon DOS agree well at energies above 10meV , the pressure behavior of the low-energy part of the DOS is not well reproduced by the theoretical calculations. In fact, they exhibit, in contrast to the experimental data, a dramatic softening of two low-energy modes, their energies approaching zero around 2.5GPa , clearly indicating the limitations of the applied shell model. These difficulties are obviously connected with the complex Sn-O and Sn-Sn bindings within and between the Sn-O-Sn layers in the litharge structure of SnO . We derived from the experimental and theoretical DOS spectra a variety of elastic and thermodynamic parameters of the Sn sublattice, such as the Lamb-Mössbauer factor, the mean force constant, and Debye temperatures, as well as the vibrational contributions to the Helmholtz free energy, specific heat, entropy, and

  3. Multi-dimensional modelling of X-ray spectra for AGN accretion-disk outflows III: application to a hydrodynamical simulation

    CERN Document Server

    Sim, S A; Miller, L; Long, K S; Turner, T J

    2010-01-01

    We perform multi-dimensional radiative transfer simulations to compute spectra for a hydrodynamical simulation of a line-driven accretion disk wind from an active galactic nucleus. The synthetic spectra confirm expectations from parameterized models that a disk wind can imprint a wide variety of spectroscopic signatures including narrow absorption lines, broad emission lines and a Compton hump. The formation of these features is complex with contributions originating from many of the different structures present in the hydrodynamical simulation. In particular, spectral features are shaped both by gas in a successfully launched outflow and in complex flows where material is lifted out of the disk plane but ultimately falls back. We also confirm that the strong Fe Kalpha line can develop a weak, red-skewed line wing as a result of Compton scattering in the outflow. In addition, we demonstrate that X-ray radiation scattered and reprocessed in the flow has a pivotal part in both the spectrum formation and determi...

  4. Suzaku discovery of iron absorption lines in outburst spectra of the X-ray transient 4U 1630-472

    CERN Document Server

    Kubota, A; Cottam, J; Kotani, T; Done, C; Ueda, Y; Fabian, A C; Yasuda, T; Takahashi, H; Fukazawa, Y; Yamaoka, K; Makishima, K; Yamada, S; Kohmura, T; Angelini, L; Kubota, Aya; Dotani, Tadayasu; Cottam, Jean; Kotani, Taro; Done, Chris; Ueda, Yoshihiro; Fabian, Andrew C.; Yasuda, Tomonori; Takahashi, Hiromitsu; Fukazawa, Yasushi; Yamaoka, Kazutaka; Makishima, Kazuo; Yamada, Shinya; Kohmura, Takayoshi; Angelini, Lorella

    2006-01-01

    We present the results of six Suzaku observations of the recurrent black hole transient 4U1630-472 during its decline from outburst from February 8 to March 23 in 2006. All observations show the typical high/soft state spectral shape in the 2-50keV band, roughly described by an optically thick disk spectrum in the soft energy band plus a weak power-law tail that becomes dominant only above \\~20keV. The disk temperature decreases from 1.4keV to 1.2keV as the flux decreases by a factor 2, consistent with a constant radius as expected for disk-dominated spectra. All the observations reveal significant absorption lines from highly ionized (H-like and He-like) iron Ka at 7.0keV and 6.7keV. The brightest datasets also show significant but weaker absorption structures between 7.8keV and 8.2keV, which we identify as a blend of iron Kb and nickel Ka absorption lines. The energies of these absorption lines suggest a blue shift with an outflow velocity of ~1000km/s.. The H-like iron Ka equivalent width remains approxima...

  5. Broad Band X-ray Spectra of Atoll Source 4U 1636-536: NuSTAR and Swift Results

    CERN Document Server

    Agrawal, Vivek Kumar

    2016-01-01

    In this work we investigate broad band (1-79 keV) spectral nature of the atoll source 4U 1636-536 using the combined Nu-STAR and SWIFT-XRT data. The spectra are complex and have emission components from the disc, boundary-layer and corona. In addition to that a broad iron line is also observed. A relativistic line model assuming Schwarzchild metric fits this feature. The total flux varies from 1.4 $\\times$ 10$^{-9}$ to 4.36 $\\times$ 10$^{-9}$ $ergs/s/cm^2$. At the highest flux level the source was found in the soft state. In this state the Comptonized component has temperature $kT_e \\sim 3$ keV and optical depth $\\tau \\sim $ 16. We also detect a non-thermal tail with index $\\sim$ 2.4, contributing $\\sim$ 10 \\% of the total flux in the soft state. We also find that the inner disc radius, electron temperature and optical depth vary with the total 0.1-100 keV unabsorbed flux. We discuss the implication of the results in this paper.

  6. Broadband Spectra and Variability of BL Lacertae in 2000

    CERN Document Server

    Böttcher, M; Aller, M F; Mang, O; Raiteri, C M; Ravasio, M; Tagliaferri, G; Teraesranta, H; Villata, M

    2002-01-01

    We have organized an extensive multiwavelength campaign on BL Lacertae in the second half of 2000. Simultaneous or quasi-simultaneous observations were taken at radio frequencies, in the optical - carried out by the WEBT collaboration -, in X-rays - using BeppoSAX and RXTE -, and at VHE gamma-rays with the CAT and HEGRA Cherenkov telescope facilities. In this paper, we are presenting first results from this campaign. The WEBT optical campaign achieved an unprecedented time coverage, virtually continuous over several 10 - 20 hour segments, and revealed intraday variability on time scales of ~ 1.5 hours. The X-ray observations of Nov. 1 - 2, 2000, revealed significant variability on similar time scales, and provided evidence for the synchrotron spectrum extending out to ~ 10 keV during that time. At higher energies, the onset of the hard power-law commonly observed in radio-loud quasars and radio-selected BL Lac objects is seen. From the energy-resolved X-ray variability patterns, we find evidence that electron...

  7. Core-level spectra and binding energies of transition metal nitrides by non-destructive x-ray photoelectron spectroscopy through capping layers

    Science.gov (United States)

    Greczynski, G.; Primetzhofer, D.; Lu, J.; Hultman, L.

    2017-02-01

    We present the first measurements of x-ray photoelectron spectroscopy (XPS) core level binding energies (BE:s) for the widely-applicable group IVb-VIb polycrystalline transition metal nitrides (TMN's) TiN, VN, CrN, ZrN, NbN, MoN, HfN, TaN, and WN as well as AlN and SiN, which are common components in the TMN-based alloy systems. Nitride thin film samples were grown at 400 °C by reactive dc magnetron sputtering from elemental targets in Ar/N2 atmosphere. For XPS measurements, layers are either (i) Ar+ ion-etched to remove surface oxides resulting from the air exposure during sample transfer from the growth chamber into the XPS system, or (ii) in situ capped with a few nm thick Cr or W overlayers in the deposition system prior to air-exposure and loading into the XPS instrument. Film elemental composition and phase content is thoroughly characterized with time-of-flight elastic recoil detection analysis (ToF-E ERDA), Rutherford backscattering spectrometry (RBS), and x-ray diffraction. High energy resolution core level XPS spectra acquired with monochromatic Al Kα radiation on the ISO-calibrated instrument reveal that even mild etching conditions result in the formation of a nitrogen-deficient surface layer that substantially affects the extracted binding energy values. These spectra-modifying effects of Ar+ ion bombardment increase with increasing the metal atom mass due to an increasing nitrogen-to-metal sputter yield ratio. The superior quality of the XPS spectra obtained in a non-destructive way from capped TMN films is evident from that numerous metal peaks, including Ti 2p, V 2p, Zr 3d, and Hf 4f, exhibit pronounced satellite features, in agreement with previously published spectra from layers grown and analyzed in situ. In addition, the N/metal concentration ratios are found to be 25-90% higher than those obtained from the corresponding ion-etched surfaces, and in most cases agree very well with the RBS and ToF-E ERDA values. The N 1 s BE:s extracted from

  8. Extremity x-ray

    Science.gov (United States)

    ... degenerative) Bone tumor Broken bone (fracture) Dislocated bone Osteomyelitis (infection) Arthritis Other conditions for which the test ... Bone tumor Bone x-ray Broken bone Clubfoot Osteomyelitis X-ray Review Date 7/3/2016 Updated ...

  9. Abdominal x-ray

    Science.gov (United States)

    ... are, or may be, pregnant. Alternative Names Abdominal film; X-ray - abdomen; Flat plate; KUB x-ray ... Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also ...

  10. Preparation of platinum(IV) complexes with dipeptide and diimine. X-ray crystal structure and 195Pt NMR spectra.

    Science.gov (United States)

    Watabe, Masatoshi; Fukuda, Hiroto; Kitsukawa, Koichiro; Nakajima, Hiroshi; Yukawa, Yasuhiko; Igarashi, Satoshi; Fujii, Yuki; Takayama, Toshio

    2006-10-01

    We prepared platinum(IV) complexes containing dipeptide and diimine or diamine, the [PtCl(dipeptide-N,N,O)(diimine or diamine)]Cl complex, where -N,N,O means dipeptide coordinated as a tridentate chelate, dipeptide=glycylglycine (NH(2)CH(2)CON(-)CH(2)COO(-), digly, where two protons of dipeptide are detached when the dipeptide coordinates to metal ion as a tridentate chelate), glycyl-L-alanine (NH(2)CH(2)CON(-)CHCH(3)COO(-), gly-L-ala), L-alanylglycine (NH(2)CH CH(3)CON(-)CH(2)COO(-), L-alagly), or L-alanyl-L-alanine (NH(2)CHCH(3)CON(-)CHCH(3)COO(-), dil-ala), and diimine or diamine=bipyridine (bpy), ethylenediamine (en), N-methylethylenediamine (N-Me-en), or N,N'-dimethylethylenediamine (N,N'-diMe-en). In the complexes containing gly-L-ala or dil-ala, two separate peaks of the (195)Pt NMR spectra of the [PtCl(dipeptide-N,N,O)(diimine or diamine)]Cl complexes appeared in, but in the complexes containing digly or L-alagly, one peak which contained two overlapped signals appeared. One of the two complexes containing gly-L-ala and bpy, [PtCl(gly-L-ala-N,N,O)(bpy)]NO(3), crystallized and was analyzed. This complex has the monoclinic space group P2(1)2(1)2(1) with unit cell dimensions of a=9.7906(3)A, b=11.1847(2)A, c=16.6796(2)A, Z=4. The crystal data revealed that this [PtCl(gly-L-ala-N,N,O)(bpy)]NO(3) complex has the near- (Cl, CH(3)) configuration of two possible isomers. Based on elemental analysis, the other complex must have the near- (Cl, CH(3))-[PtCl(gly-L-ala-N,N,O)(bpy)]NO(3) configuration. The (195)Pt NMR chemical shifts of the near- (Cl, CH(3))-[PtCl(gly-L-ala-N,N,O)(bpy)]NO(3) complex and the far- (Cl, CH(3))-[PtCl(gly-L-ala-N,N,O)(bpy)]NO(3) complex are 0 ppm and -19 ppm, respectively (0 ppm for the Na(2)[PtCl(6)] signal). The additive property of the (195)Pt NMR chemical shift is discussed. The (195)Pt NMR chemical shifts of [PtCl(dipeptide-N,N,O)(bpy)]Cl appeared at a higher field when the H attached to the dipeptide carbon atom was replaced with a

  11. Log-parabolic spectra and particle acceleration in blazars - II: The BeppoSAX wide band X-ray spectra of Mkn 501

    CERN Document Server

    Massaro, E; Giommi, P; Nesci, R; Verrecchia, F

    2004-01-01

    We present the results of a spectral and temporal study of the complete set of BeppoSAX NFI (11) and WFC (71) observations of the BL Lac object Mkn 501. The WFC 2-28 keV data, reported here for the first time, were collected over a period of about five years, from September 1996 to October 2001. These observations, although not evenly distributed, show that Mkn 501, after going through a very active phase from spring 1997 to early 1999, remained in a low brightness state until late 2001. The data from the LECS, MECS and PDS instruments, covering the wide energy interval 0.1-150 keV, have been used to study in detail the spectral variability of the source. We show that the X-ray energy distribution of Mkn 501 is well described by a log-parabolic law in all luminosity states. This model allowed us to obtain good estimates of the SED synchrotron peak energy and of its associated power. The strong spectral variability observed, consisting of strictly correlated changes between the synchrotron peak energy and bolo...

  12. A Test of Thick-Target Nonuniform Ionization as an Explanation for Breaks in Solar Flare Hard X-Ray Spectra

    Science.gov (United States)

    Holman, gordon; Dennis Brian R.; Tolbert, Anne K.; Schwartz, Richard

    2010-01-01

    Solar nonthermal hard X-ray (HXR) flare spectra often cannot be fitted by a single power law, but rather require a downward break in the photon spectrum. A possible explanation for this spectral break is nonuniform ionization in the emission region. We have developed a computer code to calculate the photon spectrum from electrons with a power-law distribution injected into a thick-target in which the ionization decreases linearly from 100% to zero. We use the bremsstrahlung cross-section from Haug (1997), which closely approximates the full relativistic Bethe-Heitler cross-section, and compare photon spectra computed from this model with those obtained by Kontar, Brown and McArthur (2002), who used a step-function ionization model and the Kramers approximation to the cross-section. We find that for HXR spectra from a target with nonuniform ionization, the difference (Delta-gamma) between the power-law indexes above and below the break has an upper limit between approx.0.2 and 0.7 that depends on the power-law index delta of the injected electron distribution. A broken power-law spectrum with a. higher value of Delta-gamma cannot result from nonuniform ionization alone. The model is applied to spectra obtained around the peak times of 20 flares observed by the Ramaty High Energy Solar Spectroscopic Imager (RHESSI from 2002 to 2004 to determine whether thick-target nonuniform ionization can explain the measured spectral breaks. A Monte Carlo method is used to determine the uncertainties of the best-fit parameters, especially on Delta-gamma. We find that 15 of the 20 flare spectra require a downward spectral break and that at least 6 of these could not be explained by nonuniform ionization alone because they had values of Delta-gamma with less than a 2.5% probability of being consistent with the computed upper limits from the model. The remaining 9 flare spectra, based on this criterion, are consistent with the nonuniform ionization model.

  13. Searching for supergiant fast X-ray transients with Swift

    CERN Document Server

    Romano, P; Esposito, P; Sbarufatti, B; Haberl, F; Ponti, G; D'Avanzo, P; Ducci, L; Segreto, A; Jin, C; Masetti, N; Del Santo, M; Campana, S; Mangano, V

    2016-01-01

    Supergiant fast X-ray transients (SFXTs) are high mass X-ray binaries (HMXBs) hosting a neutron star and an OB supergiant companion. We examine the available Swift data, as well as other new or archival/serendipitous data, on three sources: IGR J17407-2808, 2XMM J185114.3-000004, and IGR J18175-2419, whose X-ray characteristics qualify them as candidate SFXT, in order to explore their properties and test whether they are consistent with an SFXT nature. As IGR J17407-2808 and 2XMM J185114.3-000004 triggered the Burst Alert Telescope on board Swift, the Swift data allow us to provide their first arcsecond localisations, leading to an unequivocal identification of the source CXOU J174042.0-280724 as the soft X-ray counterpart of IGR J17407-2808, as well as their first broadband spectra, which can be fit with models generally describing accreting neutron stars in HMXBs. While still lacking optical spectroscopy to assess the spectral type of the companion, we propose 2XMM J185114.3-000004 as a very strong SFXT can...

  14. The Soft X-ray Imager on board EXIST

    CERN Document Server

    Natalucci, L; Panessa, F; Ubertini, P; Tagliaferri, G; Della Ceca, R; Ghisellini, G; Pareschi, G; Villa, G; Caraveo, P; Fiorini, M; Uslenghi, M; Grindlay, J E; Ramsey, B

    2010-01-01

    The Soft X-ray Imager (SXI) is one of the three instruments on board EXIST, a multi-wavelength observatory in charge of performing a global survey of the sky in hard X-rays searching for Super-massive Black Holes (Grindlay & Natalucci, these Proceedings). One of the primary objectives of EXIST is also to study with unprecedented sensitivity the most unknown high energy sources in the Universe, like high redshift GRBs, which will be pointed promptly by the Spacecraft by autonomous trigger based on hard X-ray localization on board. The presence of a soft X-ray telescope with an effective area of about 950cm2 in the energy band 0.2-3 keV and extended response up to 10 keV will allow to make broadband studies from 0.1 to 600 keV. In particular, investigations of the spectra components and states of AGNs and monitoring of variability of sources, study of the prompt and afterglow emission of GRBs since the early phases, which will help to constrain the emission models and finally, help the identification of sou...

  15. Two Novel μ-Oxo Diiron(Ⅲ) Schiff Base Complexes: X-ray Diffraction Analyses, IR, UV-Vis, CD spectra, Magnetic Susceptibility and Electrochemistry

    Institute of Scientific and Technical Information of China (English)

    阮文娟; 胡国航; 王树军; 田建华; 王庆伦; 朱志昂

    2005-01-01

    The novel μ-oxo diiron(Ⅲ) Schiff base complexes, {[Fe(tbusalphn)]2(μ-O)} (1) [tbusalphn=N,N'-o-pheny-lenebis(3,5-di-tert-butylsalicylideneiminato)] and { [Fe(R,R-salchxn)]2(μ-O)} (2) [R,R-salchxn=N,N'-R,R-cyclo-hexanebis(salicylideneiminato)] have been synthesized and characterized by elemental analyses, spectroscopy,magnetic susceptibility, electrochemical measurements and X-ray diffraction techniques. X-my analyses revealed that the complex 1-CH3OH has nearly linear Fe-O-Fe angle of 176.5(2)° due to their steric crowding of ligands owing bulky substitute group, while fairly bent Fe-O-Fe angle was allowed by the reduced steric crowding of the ligands in 2-CaH6N2-0.5C2H5OH [149.6(1)°]. FT-IR, UV-Vis, CD spectra, magnetic susceptibility and cyclic voltammogram (CV) of complexes 1 and 2 have been further investigated.

  16. The ultraluminous X-ray sources NGC 1313 X-1 and X-2: A broadband study with NuSTAR and XMM-Newton

    Energy Technology Data Exchange (ETDEWEB)

    Bachetti, Matteo; Barret, Didier; Webb, Natalie A. [Université de Toulouse, UPS-OMP, IRAP, Toulouse (France); Rana, Vikram; Walton, Dominic J.; Harrison, Fiona A.; Fürst, Felix; Grefenstette, Brian W.; Madsen, Kristin K. [Cahill Center for Astronomy and Astrophysics, Caltech, Pasadena, CA 91125 (United States); Boggs, Steven E.; Craig, William W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Christensen, Finn E. [DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Fabian, Andrew C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Hailey, Charles J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Hornschemeier, Ann; Ptak, Andrew F.; Zhang, William W. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Miller, Jon M. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042 (United States); Stern, Daniel, E-mail: matteo.bachetti@irap.omp.eu [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

    2013-12-01

    We present the results of NuSTAR and XMM-Newton observations of the two ultraluminous X-ray sources: NGC 1313 X-1 and X-2. The combined spectral bandpass of the two satellites enables us to produce the first spectrum of X-1 between 0.3 and 30 keV, while X-2 is not significantly detected by NuSTAR above 10 keV. The NuSTAR data demonstrate that X-1 has a clear cutoff above 10 keV, whose presence was only marginally detectable with previous X-ray observations. This cutoff rules out the interpretation of X-1 as a black hole in a standard low/hard state, and it is deeper than predicted for the downturn of a broadened iron line in a reflection-dominated regime. The cutoff differs from the prediction of a single-temperature Comptonization model. Further, a cold disk-like blackbody component at ∼0.3 keV is required by the data, confirming previous measurements by XMM-Newton only. We observe a spectral transition in X-2, from a state with high luminosity and strong variability to a lower-luminosity state with no detectable variability, and we link this behavior to a transition from a super-Eddington to a sub-Eddington regime.

  17. X-Ray Supernovae

    CERN Document Server

    Immler, S; Immler, Stefan; Lewin, Walter H.G.

    2002-01-01

    We present a review of X-ray observations of supernovae (SNe). By observing the (~0.1--100 keV) X-ray emission from young SNe, physical key parameters such as the circumstellar matter (CSM) density, mass-loss rate of the progenitor and temperature of the outgoing and reverse shock can be derived as a function of time. Despite intensive search over the last ~25 years, only 15 SNe have been detected in X-rays. We review the individual X-ray observations of these SNe and discuss their implications as to our understanding of the physical processes giving rise to the X-ray emission.

  18. An iterative method in a probabilistic approach to the spectral inverse problem: Differential emission measure from line spectra and broadband data

    CERN Document Server

    Goryaev, F F; Urnov, A M; Oparin, S N; Hochedez, J -F; Reale, F; 10.1051/0004-6361/201014280

    2010-01-01

    Inverse problems are of great importance in astrophysics for deriving information about the physical characteristics of hot optically thin plasma sources from their EUV and X-ray spectra. We describe and test an iterative method developed within the framework of a probabilistic approach to the spectral inverse problem for determining the thermal structures of the emitting plasma. We also demonstrate applications of this method to both high resolution line spectra and broadband imaging data. Our so-called Bayesian iterative method (BIM) is an iterative procedure based on Bayes' theorem and is used to reconstruct differential emission measure (DEM) distributions. To demonstrate the abilities of the BIM, we performed various numerical tests and model simulations establishing its robustness and usefulness. We then applied the BIM to observable data for several active regions (AR) previously analyzed with other DEM diagnostic techniques: both SUMER/SOHO (Landi and Feldman, 2008) and SPIRIT/CORONAS-F (Shestov et al...

  19. Accelerator-driven X-ray Sources

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Dinh Cong [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-09

    After an introduction which mentions x-ray tubes and storage rings and gives a brief review of special relativity, the subject is treated under the following topics and subtopics: synchrotron radiation (bending magnet radiation, wiggler radiation, undulator radiation, brightness and brilliance definition, synchrotron radiation facilities), x-ray free-electron lasers (linac-driven X-ray FEL, FEL interactions, self-amplified spontaneous emission (SASE), SASE self-seeding, fourth-generation light source facilities), and other X-ray sources (energy recovery linacs, Inverse Compton scattering, laser wakefield accelerator driven X-ray sources. In summary, accelerator-based light sources cover the entire electromagnetic spectrum. Synchrotron radiation (bending magnet, wiggler and undulator radiation) has unique properties that can be tailored to the users’ needs: bending magnet and wiggler radiation is broadband, undulator radiation has narrow spectral lines. X-ray FELs are the brightest coherent X-ray sources with high photon flux, femtosecond pulses, full transverse coherence, partial temporal coherence (SASE), and narrow spectral lines with seeding techniques. New developments in electron accelerators and radiation production can potentially lead to more compact sources of coherent X-rays.

  20. The ultraluminous x-ray sources ngc 1313 x-1 and x-2: a broadband study with NuSTAR and XMM-Newton

    DEFF Research Database (Denmark)

    Bachetti, Matteo; Rana, Vikram; Walton, Dominic J.;

    2013-01-01

    We present the results of NuSTAR and XMM-Newton observations of the two ultraluminous X-ray sources: NGC 1313 X-1 and X-2. The combined spectral bandpass of the two satellites enables us to produce the first spectrum of X-1 between 0.3 and 30 keV, while X-2 is not significantly detected by Nu...... for the downturn of a broadened iron line in a reflection-dominated regime. The cutoff differs from the prediction of a single-temperature Comptonization model. Further, a cold disk-like blackbody component at similar to 0.3 keV is required by the data, confirming previous measurements by XMM-Newton only. We...

  1. Correlation of O (1s) and Fe (2p) near edge x-ray absorption fine structure spectra and electrical conductivity of La1-xSrxFe0.75Ni0.25O3-δ

    Science.gov (United States)

    Erat, Selma; Braun, Artur; Ovalle, Alejandro; Piamonteze, Cinthia; Liu, Zhi; Graule, Thomas; Gauckler, Ludwig J.

    2009-10-01

    A-site substitution of La3+ by Sr2+ in polaron conducting ABO3-type perovskite La1-xSrxFe0.75Ni0.25O3-δ causes oxidation of Fe3+ toward Fe4+ and formation of conducting electron holes, as evidenced by Fe (2p) and O (1s) near edge x-ray absorption fine structure spectra. Hole doping is reflected by linear variation of the prepeak ratio eg(↑)/[t2g(↓)+eg(↓)] of oxygen spectra, along with increased conductivity. The significant increase in conductivity due to NiO doping in La1-xSrxFeO3-δ is caused by increased overlap between Fe (3d) and O (2p) and charge transfer from the O (2p) to the Ni (3d) states, as concluded from near edge x-ray absorption fine structure spectra and ligand field multiplet calculations.

  2. X-raying clumped stellar winds

    CERN Document Server

    Oskinova, L M; Feldmeier, A

    2008-01-01

    X-ray spectroscopy is a sensitive probe of stellar winds. X-rays originate from optically thin shock-heated plasma deep inside the wind and propagate outwards throughout absorbing cool material. Recent analyses of the line ratios from He-like ions in the X-ray spectra of O-stars highlighted problems with this general paradigm: the measured line ratios of highest ions are consistent with the location of the hottest X-ray emitting plasma very close to the base of the wind, perhaps indicating the presence of a corona, while measurements from lower ions conform with the wind-embedded shock model. Generally, to correctly model the emerging X-ray spectra, a detailed knowledge of the cool wind opacities based on stellar atmosphere models is prerequisite. A nearly grey stellar wind opacity for the X-rays is deduced from the analyses of high-resolution X-ray spectra. This indicates that the stellar winds are strongly clumped. Furthermore, the nearly symmetric shape of X-ray emission line profiles can be explained if t...

  3. Hard X-ray photoelectron spectra (HXPES) of bulk non-conductor vitreous SiO{sub 2}: Minimum linewidths and surface chemical shifts

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Y.F., E-mail: Yongfeng.hu@lightsource.ca [Canadian Light Source, Saskatoon, SK (Canada); Xiao, Q.; Wang, D.; Cui, X. [Canadian Light Source, Saskatoon, SK (Canada); Nesbitt, H.W. [Department of Earth Sciences, University of Western Ontario, London, ONT (Canada); Bancroft, G.M. [Department of Chemistry, University of Western Ontario, London, ONT (Canada)

    2015-07-15

    Highlights: • Electronic structure of non-conducting glass studied by hard X-ray photoelectron spectroscopy. • A thin film of Cr was deposited on the vitreous SiO{sub 2} glass to overcome the sample charging. • Excellent O 1s and Si 1s linewidths were obtained, matching those reported using the laboratory based Kratos Axis Ultra spectrometer equipped with a magnetic compensation system. • The bulk and interface states of non-conducting samples are studied as a function of photon energy. - Abstract: Hard X-ray photoelectron spectra (2200 eV to 5000 eV photon energies) have been obtained for the first time on a bulk non-conductor, vitreous SiO{sub 2}, on a high resolution (E/ΔE of 10,000) synchrotron beamline at the Canadian Light Source (CLS). To minimize charging and differential charging, the SiO{sub 2} was coated with very thin layers (0.5 to 1.5 nm) of Cr metal. The O 1s linewidth obtained at 2500 eV photon energy was 1.26 eV—the minimum linewidth for SiO{sub 2}—and in good agreement with that obtained at 1486 eV on a Kratos Axis Ultra spectrometer equipped with a magnetic charge compensation system. The Si 1s linewidth of 1.5 eV, somewhat broader than that previously obtained at 1486 eV on the Si 2p{sub 3/2} line of 1.16 eV, is mainly due to the much larger inherent Si 1s linewidth (0.5 eV) compared to the inherent Si 2p linewidth (<0.1 eV). Both linewidths are dominated by the large final state vibrational broadening previously described. The Cr coating produces surface monolayers of interfacial Cr “suboxide” (Cr-subox), Cr metal, and a surface Cr oxide (Cr-surfox). Cr-subox (Si−O−Cr) gives rise to the weak near-surface Si 1s peak, while both oxides give rise to both the weak surface O 1s peak and the Cr 2p oxide peak. Both the O 1s and Si 1s surface peaks are shifted by ∼2 eV relative to the large bulk Si 1s and O 1s peaks. The weak Si 1s and O 1s surface peaks along with the Cr 2p oxide peak decrease in intensity greatly as the photon

  4. The 2003 radio outburst of a new X-ray transient: XTE J1720-318

    CERN Document Server

    Brocksopp, C; Fender, R P; Rupen, M; Sault, R; Tingay, S J; Hannikainen, D C; O'Brien, K

    2001-01-01

    We present radio observations of the black hole X-ray transient XTE J1720-318, which was discovered in 2003 January as it entered an outburst. We analyse the radio data in the context of the X-ray outburst and the broad-band spectrum. An unresolved radio source was detected during the rising phase, reaching a peak of nearly 5 mJy approximately coincident with the peak of the X-ray lightcurve. Study of the spectral indices suggests that at least two ejection events took place, the radio-emitting material expanding and becoming optically thin as it faded. The broad-band spectra suggested that the accretion disc dominated the emission, as expected for a source in the high/soft state. The radio emission decayed to below the sensitivity of the telescopes for ~6 weeks but switched on again during the transition of the X-ray source to the low/hard state. At least one ``glitch'' was superimposed on the otherwise exponential decay of the X-ray lightcurve, which was reminiscent of the multiple jet ejections of XTE J185...

  5. Dante Soft X-ray Power Diagnostic for NIF

    Energy Technology Data Exchange (ETDEWEB)

    Dewald, E; Campbell, K; Turner, R; Holder, J; Landen, O; Glenzer, S; Kauffman, R; Suter, L; Landon, M; Rhodes, M; Lee, D

    2004-04-15

    Soft x-ray power diagnostics are essential for measuring spectrally resolved the total x-ray flux, radiation temperature, conversion efficiency and albedo that are important quantities for the energetics of indirect drive hohlraums. At the Nova or Omega Laser Facilities, these measurements are performed mainly with Dante, but also with DMX and photo-conductive detectors (PCD's). The Dante broadband spectrometer is a collection of absolute calibrated vacuum x-ray diodes, thin filters and x-ray mirrors used to measure the soft x-ray emission for photon energies above 50 eV.

  6. NuSTAR HARD X-RAY SURVEY OF THE GALACTIC CENTER REGION. I. HARD X-RAY MORPHOLOGY AND SPECTROSCOPY OF THE DIFFUSE EMISSION

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Kaya; Hailey, Charles J.; Perez, Kerstin; Nynka, Melania; Zhang, Shuo; Canipe, Alicia M. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Krivonos, Roman; Tomsick, John A.; Barrière, Nicolas; Boggs, Steven E.; Craig, William W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Hong, Jaesub [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Ponti, Gabriele [Max-Planck-Institut f. extraterrestrische Physik, HEG, Garching (Germany); Bauer, Franz [Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, 306, Santiago 22 (Chile); Alexander, David M. [Department of Physics, Durham University, Durham DH1 3LE (United Kingdom); Baganoff, Frederick K. [Kavli Institute for Astrophysics and Space Research, Massachusets Institute of Technology, Cambridge, MA 02139 (United States); Barret, Didier [Université de Toulouse, UPS-OMP, IRAP, Toulouse (France); Christensen, Finn E. [DTU Space—National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Forster, Karl [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Giommi, Paolo, E-mail: kaya@astro.columbia.edu [ASI Science Data Center, Via del Politecnico snc I-00133, Roma (Italy); and others

    2015-12-01

    We present the first sub-arcminute images of the Galactic Center above 10 keV, obtained with NuSTAR. NuSTAR resolves the hard X-ray source IGR J17456–2901 into non-thermal X-ray filaments, molecular clouds, point sources, and a previously unknown central component of hard X-ray emission (CHXE). NuSTAR detects four non-thermal X-ray filaments, extending the detection of their power-law spectra with Γ ∼ 1.3–2.3 up to ∼50 keV. A morphological and spectral study of the filaments suggests that their origin may be heterogeneous, where previous studies suggested a common origin in young pulsar wind nebulae (PWNe). NuSTAR detects non-thermal X-ray continuum emission spatially correlated with the 6.4 keV Fe Kα fluorescence line emission associated with two Sgr A molecular clouds: MC1 and the Bridge. Broadband X-ray spectral analysis with a Monte-Carlo based X-ray reflection model self-consistently determined their intrinsic column density (∼10{sup 23} cm{sup −2}), primary X-ray spectra (power-laws with Γ ∼ 2) and set a lower limit of the X-ray luminosity of Sgr A* flare illuminating the Sgr A clouds to L{sub X} ≳ 10{sup 38} erg s{sup −1}. Above ∼20 keV, hard X-ray emission in the central 10 pc region around Sgr A* consists of the candidate PWN G359.95–0.04 and the CHXE, possibly resulting from an unresolved population of massive CVs with white dwarf masses M{sub WD} ∼ 0.9 M{sub ⊙}. Spectral energy distribution analysis suggests that G359.95–0.04 is likely the hard X-ray counterpart of the ultra-high gamma-ray source HESS J1745–290, strongly favoring a leptonic origin of the GC TeV emission.

  7. Symbiotic Stars in X-rays

    Science.gov (United States)

    Luna, G. J. M.; Sokoloski, J. L.; Mukai, K.; Nelson, T.

    2014-01-01

    Until recently, symbiotic binary systems in which a white dwarf accretes from a red giant were thought to be mainly a soft X-ray population. Here we describe the detection with the X-ray Telescope (XRT) on the Swift satellite of 9 white dwarf symbiotics that were not previously known to be X-ray sources and one that was previously detected as a supersoft X-ray source. The 9 new X-ray detections were the result of a survey of 41 symbiotic stars, and they increase the number of symbiotic stars known to be X-ray sources by approximately 30%. Swift/XRT detected all of the new X-ray sources at energies greater than 2 keV. Their X-ray spectra are consistent with thermal emission and fall naturally into three distinct groups. The first group contains those sources with a single, highly absorbed hard component, which we identify as probably coming from an accretion-disk boundary layer. The second group is composed of those sources with a single, soft X-ray spectral component, which likely arises in a region where low-velocity shocks produce X-ray emission, i.e. a colliding-wind region. The third group consists of those sources with both hard and soft X-ray spectral components. We also find that unlike in the optical, where rapid, stochastic brightness variations from the accretion disk typically are not seen, detectable UV flickering is a common property of symbiotic stars. Supporting our physical interpretation of the two X-ray spectral components, simultaneous Swift UV photometry shows that symbiotic stars with harder X-ray emission tend to have stronger UV flickering, which is usually associated with accretion through a disk. To place these new observations in the context of previous work on X-ray emission from symbiotic stars, we modified and extended the alpha/beta/gamma classification scheme for symbiotic-star X-ray spectra that was introduced by Muerset et al. based upon observations with the ROSAT satellite, to include a new sigma classification for sources with

  8. A broadband X-ray spectral study of the intermediate-mass black hole candidate M82 X-1 with NuSTAR, Chandra and Swift

    CERN Document Server

    Brightman, Murray; Barret, Didier; Davis, Shane W; Fürst, Felix; Madsen, Kristin K; Middleton, Matthew; Miller, Jon M; Stern, Daniel; Tao, Lian; Walton, Dominic J

    2016-01-01

    M82 X-1 is one of the brightest ultraluminous X-ray sources (ULXs) known, which, assuming Eddington-limited accretion and other considerations, makes it one of the best intermediate-mass black hole (IMBH) candidates. However, the ULX may still be explained by super-Eddington accretion onto a stellar-remnant black hole. We present simultaneous NuSTAR, Chandra and Swift/XRT observations during the peak of a flaring episode with the aim of modeling the emission of M82 X-1 and yielding insights into its nature. We find that thin-accretion disk models all require accretion rates at or above the Eddington limit in order to reproduce the spectral shape, given a range of black hole masses and spins. Since at these high Eddington ratios the thin-disk model breaks down due to radial advection in the disk, we discard the results of the thin-disk models as unphysical. We find that the temperature profile as a function of disk radius ($T(r)\\propto r^{-p}$) is significantly flatter ($p=0.55^{+ 0.07}_{- 0.04}$) than expecte...

  9. The X-ray properties of the magnetic Cataclysmic Variable UU Col

    CERN Document Server

    De Martino, D; Mukai, K; Bonnet-Bidaud, J M; Burwitz, V; Gänsicke, B T; Haberl, F; Mouchet, M

    2006-01-01

    XMM-Newton observations aimed at determining for the first time the broad-band X-ray properties of the faint high galactic latitude Intermediate Polar UU Col are presented. We performed X-ray timing analysis in different energy ranges of the EPIC cameras which reveals the dominance of the 863s white dwarf rotational period. The spin pulse is strongly energy dependent. Weak variabilities at the beat 935s and at the 3.5hr orbital periods are also observed, but the orbital modulation is detected only below 0.5keV. Simultaneous UV and optical photometry shows that the spin pulse is anti-phased with respect to the hard X-rays. Analysis of the EPIC and RGS spectra reveals the complexity of the X-ray emission, being composed of a soft 50eV black--body component and two optically thin emission components at 0.2keV and 11keV strongly absorbed by dense material with an equivalent hydrogen column density of 10**(23)cm**(-2) partially (50%) covering the X-ray source. The complex X-ray and UV/optical temporal behaviour in...

  10. Simultaneous X-ray and optical spectroscopy of the Oef supergiant lambda Cep

    CERN Document Server

    Rauw, G; Naze, Y; Gonzalez-Perez, J N; Hempelmann, A; Mittag, M; Schmitt, J H M M; Schroeder, K -P; Gosset, E; Eenens, P; Uuh-Sonda, J M

    2015-01-01

    Probing the structures of stellar winds is of prime importance for the understanding of massive stars. Based on their optical spectral morphology and variability, the stars of the Oef class have been suggested to feature large-scale structures in their wind. High-resolution X-ray spectroscopy and time-series of X-ray observations of presumably-single O-type stars can help us understand the physics of their stellar winds. We have collected XMM-Newton observations and coordinated optical spectroscopy of the O6Ief star lambda Cep to study its X-ray and optical variability and to analyse its high-resolution X-ray spectrum. We investigate the line profile variability of the He II 4686 and H-alpha emission lines in our time series of optical spectra, including a search for periodicities. We further discuss the variability of the broadband X-ray flux and analyse the high-resolution spectrum of lambda Cep using line-by-line fits as well as a code designed to fit the full high-resolution X-ray spectrum consistently. D...

  11. X-Ray

    Science.gov (United States)

    ... You may be allowed to remain with your child during the test. If you remain in the room during the X-ray exposure, you'll likely be asked to wear a lead apron to shield you from unnecessary exposure. After the X-ray ...

  12. Dental x-rays

    Science.gov (United States)

    ... X-rays are a form of high energy electromagnetic radiation. The x-rays penetrate the body to form ... for detecting cavities, unless the decay is very advanced and deep. Many ... The amount of radiation given off during the procedure is less than ...

  13. THERMAL X-RAY EMISSION FROM THE SHOCKED STELLAR WIND OF PULSAR GAMMA-RAY BINARIES

    Energy Technology Data Exchange (ETDEWEB)

    Zabalza, V.; Paredes, J. M. [Departament d' Astronomia i Meteorologia, Institut de Ciencies del Cosmos (ICC), Universitat de Barcelona (IEEC-UB), Marti i Franques 1, E08028 Barcelona (Spain); Bosch-Ramon, V., E-mail: vzabalza@am.ub.es [Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland)

    2011-12-10

    Gamma-ray-loud X-ray binaries are binary systems that show non-thermal broadband emission from radio to gamma rays. If the system comprises a massive star and a young non-accreting pulsar, their winds will collide producing broadband non-thermal emission, most likely originated in the shocked pulsar wind. Thermal X-ray emission is expected from the shocked stellar wind, but until now it has neither been detected nor studied in the context of gamma-ray binaries. We present a semi-analytic model of the thermal X-ray emission from the shocked stellar wind in pulsar gamma-ray binaries, and find that the thermal X-ray emission increases monotonically with the pulsar spin-down luminosity, reaching luminosities of the order of 10{sup 33} erg s{sup -1}. The lack of thermal features in the X-ray spectrum of gamma-ray binaries can then be used to constrain the properties of the pulsar and stellar winds. By fitting the observed X-ray spectra of gamma-ray binaries with a source model composed of an absorbed non-thermal power law and the computed thermal X-ray emission, we are able to derive upper limits on the spin-down luminosity of the putative pulsar. We applied this method to LS 5039, the only gamma-ray binary with a radial, powerful wind, and obtain an upper limit on the pulsar spin-down luminosity of {approx}6 Multiplication-Sign 10{sup 36} erg s{sup -1}. Given the energetic constraints from its high-energy gamma-ray emission, a non-thermal to spin-down luminosity ratio very close to unity may be required.

  14. Dissecting the Accretion Environments of X-ray Binaries with High Speed Coordinated Optical and X-ray Timing Observations

    Science.gov (United States)

    Gandhi, Poshak; Durant, M.; Fabian, A. C.; Malzac, J.; Miller, J. M.; Shahbaz, T.; Dhillon, V. S.; Marsh, T. R.; Spruit, H. C.; Makishima, K.

    2010-03-01

    We are uncovering significant optical variability in low/hard state observations of several X-ray binaries on the fastest time-scales of just tens of milliseconds typically probed with modern rapid imaging cameras. The optical light curves are remarkable in that they display properties very characteristic of X-ray variations: 1) power spectra with band-limited, red noise over broad time ranges of 10 ms - 1000 s, and in some cases, a low-frequency quasi-periodic oscillation; 2) an instantaneous variability amplitude linearly scaling with source flux; and, 3) log-normal distributions of fluxes. Aperiodic optical variability components can dominate over simple linear X-ray reprocessing expectations, and are much faster than viscous time-scales of the outer accretion disk or flow. Cross-correlated optical vs. X-ray time delays not only constrain emission mechanisms, but can also be used to probe characteristic size scales of the physical components (jet, corona), and to understand how they are coupled. Rapid, multiwavelength timing studies are thus opening a new window on the hearts of accreting sources, though the broad-band spectral plus timing properties remain to be unified consistently. I will briefly review recent results on rapid optical variability, including our new data on black hole and neutron star binary systems. The fact that the sources were all in typical low/hard states (with relatively-bright optical counterparts) suggests that correlated optical/X-ray activity may be a general feature, waiting to be uncovered in more systems. The continuance of RXTE is vital for such work.

  15. Effects of chirp of pump pulses on broadband terahertz pulse spectra generated by optical rectification

    Science.gov (United States)

    Hamazaki, Junichi; Furusawa, Kentaro; Sekine, Norihiko; Kasamatsu, Akifumi; Hosako, Iwao

    2016-11-01

    The effects of the chirp of the pump pulse in broadband terahertz (THz) pulse generation by optical rectification (OR) in GaP were systematically investigated. It was found that the pre-compensation for the dispersion of GaP is important for obtaining smooth and single-peaked THz spectra as well as high power-conversion efficiency. It was also found that an excessive amount of chirp leads to distortions in THz spectra, which can be quantitatively analyzed by using a simple model. Our results highlight the importance of accurate control over the chirp of the pump pulse for generating broadband THz pulses by OR.

  16. X-Ray Surveys

    CERN Document Server

    Giommi, P; Perri, M

    1998-01-01

    A review of recent developments in the field of X-ray surveys, especially in the hard (2-10 and 5-10 keV) bands, is given. A new detailed comparison between the measurements in the hard band and extrapolations from ROSAT counts, that takes into proper account the observed distribution of spectral slopes, is presented. Direct comparisons between deep ROSAT and BeppoSAX images show that most hard X-ray sources are also detected at soft X-ray energies. This may indicate that heavily cutoff sources, that should not be detectable in the ROSAT band but are expected in large numbers from unified AGN schemes, are in fact detected because of the emerging of either non-nuclear components, or of reflected, or partially transmitted nuclear X-rays. These soft components may complicate the estimation of the soft X-ray luminosity function and cosmological evolution of AGN.

  17. Laser plasma x-ray source for ultrafast time-resolved x-ray absorption spectroscopy.

    Science.gov (United States)

    Miaja-Avila, L; O'Neil, G C; Uhlig, J; Cromer, C L; Dowell, M L; Jimenez, R; Hoover, A S; Silverman, K L; Ullom, J N

    2015-03-01

    We describe a laser-driven x-ray plasma source designed for ultrafast x-ray absorption spectroscopy. The source is comprised of a 1 kHz, 20 W, femtosecond pulsed infrared laser and a water target. We present the x-ray spectra as a function of laser energy and pulse duration. Additionally, we investigate the plasma temperature and photon flux as we vary the laser energy. We obtain a 75 μm FWHM x-ray spot size, containing ∼10(6) photons/s, by focusing the produced x-rays with a polycapillary optic. Since the acquisition of x-ray absorption spectra requires the averaging of measurements from >10(7) laser pulses, we also present data on the source stability, including single pulse measurements of the x-ray yield and the x-ray spectral shape. In single pulse measurements, the x-ray flux has a measured standard deviation of 8%, where the laser pointing is the main cause of variability. Further, we show that the variability in x-ray spectral shape from single pulses is low, thus justifying the combining of x-rays obtained from different laser pulses into a single spectrum. Finally, we show a static x-ray absorption spectrum of a ferrioxalate solution as detected by a microcalorimeter array. Altogether, our results demonstrate that this water-jet based plasma source is a suitable candidate for laboratory-based time-resolved x-ray absorption spectroscopy experiments.

  18. Laser plasma x-ray source for ultrafast time-resolved x-ray absorption spectroscopy

    Directory of Open Access Journals (Sweden)

    L. Miaja-Avila

    2015-03-01

    Full Text Available We describe a laser-driven x-ray plasma source designed for ultrafast x-ray absorption spectroscopy. The source is comprised of a 1 kHz, 20 W, femtosecond pulsed infrared laser and a water target. We present the x-ray spectra as a function of laser energy and pulse duration. Additionally, we investigate the plasma temperature and photon flux as we vary the laser energy. We obtain a 75 μm FWHM x-ray spot size, containing ∼106 photons/s, by focusing the produced x-rays with a polycapillary optic. Since the acquisition of x-ray absorption spectra requires the averaging of measurements from >107 laser pulses, we also present data on the source stability, including single pulse measurements of the x-ray yield and the x-ray spectral shape. In single pulse measurements, the x-ray flux has a measured standard deviation of 8%, where the laser pointing is the main cause of variability. Further, we show that the variability in x-ray spectral shape from single pulses is low, thus justifying the combining of x-rays obtained from different laser pulses into a single spectrum. Finally, we show a static x-ray absorption spectrum of a ferrioxalate solution as detected by a microcalorimeter array. Altogether, our results demonstrate that this water-jet based plasma source is a suitable candidate for laboratory-based time-resolved x-ray absorption spectroscopy experiments.

  19. Reconstruction of Spectra Using X-ray Flat Panel Detector; Reconstruccion de Espectros de Rayos X Utilizando un Detector Flat Panel

    Energy Technology Data Exchange (ETDEWEB)

    Gallardo, S.; Querol, A.; Pozuelo, F.; Juste, B.; Rodenas, J.; Verdu, G.

    2013-07-01

    In this work, we used a flat panel detector with a wedge of PMMA for absorbed dose curve for given working conditions of X-ray tube The relationship between absorbed dose curve recorded by the flat panel and primary X-ray spectrum is defined by a response function that can be obtained using the Monte Carlo method, namely the MCNP5 code. However there are some problems that affect the applicability of this method such as: flat panel characteristics and the characteristics of the physical process (ill-conditioned problem). Both aspects are discussed in this paper.

  20. An X-ray view of quasars

    CERN Document Server

    Singh, K P

    2013-01-01

    I present an overview of observational studies of quasars of all types, with particular emphasis on X-ray observational studies. The presentation is based on the most popularly accepted unified picture of quasars - collectively referred to as AGN (active galactic nuclei) in this review. Characteristics of X-ray spectra and X-ray variability obtained from various X-ray satellites over the last 5 decades have been presented and discussed. The contribution of AGN in understanding the cosmic X-ray background is discussed very briefly. Attempt has been made to provide up-to-date information; however, this is a vast subject and this presentation is not intended to be comprehensive.

  1. X-ray crystallography

    Science.gov (United States)

    2001-01-01

    X-rays diffracted from a well-ordered protein crystal create sharp patterns of scattered light on film. A computer can use these patterns to generate a model of a protein molecule. To analyze the selected crystal, an X-ray crystallographer shines X-rays through the crystal. Unlike a single dental X-ray, which produces a shadow image of a tooth, these X-rays have to be taken many times from different angles to produce a pattern from the scattered light, a map of the intensity of the X-rays after they diffract through the crystal. The X-rays bounce off the electron clouds that form the outer structure of each atom. A flawed crystal will yield a blurry pattern; a well-ordered protein crystal yields a series of sharp diffraction patterns. From these patterns, researchers build an electron density map. With powerful computers and a lot of calculations, scientists can use the electron density patterns to determine the structure of the protein and make a computer-generated model of the structure. The models let researchers improve their understanding of how the protein functions. They also allow scientists to look for receptor sites and active areas that control a protein's function and role in the progress of diseases. From there, pharmaceutical researchers can design molecules that fit the active site, much like a key and lock, so that the protein is locked without affecting the rest of the body. This is called structure-based drug design.

  2. X-ray lasers

    CERN Document Server

    Elton, Raymond C

    2012-01-01

    The first in its field, this book is both an introduction to x-ray lasers and a how-to guide for specialists. It provides new entrants and others interested in the field with a comprehensive overview and describes useful examples of analysis and experiments as background and guidance for researchers undertaking new laser designs. In one succinct volume, X-Ray Lasers collects the knowledge and experience gained in two decades of x-ray laser development and conveys the exciting challenges and possibilities still to come._Add on for longer version of blurb_M>The reader is first introduced

  3. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... Resources Professions Site Index A-Z X-ray (Radiography) - Bone Bone x-ray uses a very small ... X-ray (Radiography)? What is Bone X-ray (Radiography)? An x-ray (radiograph) is a noninvasive medical ...

  4. Application of Monte Carlo Method in the Analysis of Materials. Used in Flat Panel Detectors to Get X-ray spectra; Aplicacion del Metodo de Monte Carlo en el Analisis de Materiales Utilizados en Detectores Flat Panel para Obtener Espectros de Rayos X

    Energy Technology Data Exchange (ETDEWEB)

    Gallardo, S.; Pozuelo, F.; Querol, A.; Rodenas, J.; Verdu, G.

    2013-07-01

    They have used various methods of reconstruction for the X-ray spectrum curve knowing the dose-response function. The results demonstrate that the method modified truncated singular value decomposition (MTSVD) is appropriate to reconstruct the spectra of X-ray scintillator materials studied in this work.

  5. The Need for X-Ray Spectroscopy

    Science.gov (United States)

    Winebarger, Amy R.; Cirtain, Jonathan; Kobayashi, Ken

    2011-01-01

    For over four decades, X-ray, EUV, and UV spectral observations have been used to measure physical properties of the solar atmosphere. During this time, there has been substantial improvement in the spectral, spatial, and temporal resolution of the observations for the EUV and UV wavelength ranges. At wavelengths below 100 Angstroms, however, observations of the solar corona with simultaneous spatial and spectral resolution are limited, and not since the late 1970's have spatially resolved solar X-ray spectra been measured. The soft-X-ray wavelength range is dominated by emission lines formed at high temperatures and provides diagnostics unavailable in any other wavelength range. In this presentation, we will discuss the important science questions that can be answered using spatially and spectrally resolved X-ray spectra.

  6. Bone x-ray

    Science.gov (United States)

    ... or broken bone Bone tumors Degenerative bone conditions Osteomyelitis (inflammation of the bone caused by an infection) ... Multiple myeloma Osgood-Schlatter disease Osteogenesis imperfecta Osteomalacia Osteomyelitis Paget disease of the bone Rickets X-ray ...

  7. Hand x-ray

    Science.gov (United States)

    ... include fractures, bone tumors , degenerative bone conditions, and osteomyelitis (inflammation of the bone caused by an infection). ... chap 46. Read More Bone tumor Broken bone Osteomyelitis X-ray Review Date 9/8/2014 Updated ...

  8. Pelvis x-ray

    Science.gov (United States)

    X-ray - pelvis ... Tumors Degenerative conditions of bones in the hips, pelvis, and upper legs ... hip joint Tumors of the bones of the pelvis Sacroiliitis (inflammation of the area where the sacrum ...

  9. Chest X-Ray

    Medline Plus

    Full Text Available ... and use a very small dose of ionizing radiation to produce pictures of the inside of the ... x-ray use a tiny dose of ionizing radiation, the benefit of an accurate diagnosis far outweighs ...

  10. Chest X-Ray

    Medline Plus

    Full Text Available ... Index A-Z Spotlight October is National Breast Cancer Awareness Month Recently posted: Medical Imaging Costs Magnetoencephalography ( ... of lung conditions such as pneumonia, emphysema and cancer. A chest x-ray requires no special preparation. ...

  11. Chest X-Ray

    Medline Plus

    Full Text Available ... chest x-ray is used to evaluate the lungs, heart and chest wall and may be used ... diagnose and monitor treatment for a variety of lung conditions such as pneumonia, emphysema and cancer. A ...

  12. X-ray - skeleton

    Science.gov (United States)

    ... x-ray particles pass through the body. A computer or special film records the images. Structures that ... M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health ...

  13. X-Ray Diffraction.

    Science.gov (United States)

    Smith, D. K.; Smith, K. L.

    1980-01-01

    Reviews applications in research and analytical characterization of compounds and materials in the field of X-ray diffraction, emphasizing new developments in applications and instrumentation in both single crystal and powder diffraction. Cites 414 references. (CS)

  14. Chest X-Ray

    Medline Plus

    Full Text Available ... breath, persistent cough, fever, chest pain or injury. It may also be useful to help diagnose and ... have some concerns about chest x-rays. However, it’s important to consider the likelihood of benefit to ...

  15. X-Ray Diffraction.

    Science.gov (United States)

    Smith, D. K.; Smith, K. L.

    1980-01-01

    Reviews applications in research and analytical characterization of compounds and materials in the field of X-ray diffraction, emphasizing new developments in applications and instrumentation in both single crystal and powder diffraction. Cites 414 references. (CS)

  16. Chest X-Ray

    Medline Plus

    Full Text Available ... breath, persistent cough, fever, chest pain or injury. It may also be useful to help diagnose and ... have some concerns about chest x-rays. However, it’s important to consider the likelihood of benefit to ...

  17. Chest X-Ray

    Medline Plus

    Full Text Available ... CT Angiography Video: Myelography Video: CT of the Heart Video: Radioiodine I-131 Therapy Radiology and You ... x-ray is used to evaluate the lungs, heart and chest wall and may be used to ...

  18. Warm Absorbers in X-rays (WAX), a comprehensive high resolution grating spectral study of a sample of Seyfert galaxies

    Science.gov (United States)

    Laha, S.; Guainazzi, M.; Dewangan, G.; Chakravorty, S.; Kembhavi, A.

    2014-07-01

    We present results from a homogeneous analysis of the broadband 0.3-10 keV CCD resolution as well as of soft X-ray high-resolution grating spectra of a hard X-ray flux-limited sample of 26 Seyfert galaxies observed with XMM-Newton. We could put a strict lower limit on the detection fraction of 50%. We find a gap in the distribution of the ionisation parameter in the range 0.5UFOs) do not represent extreme manifestation of the same astrophysical system.

  19. Spectroscopy in X-ray astronomy

    Science.gov (United States)

    Andresen, R.

    1981-01-01

    Detailed features in cosmic X-ray sources and their associated temporal variation over a wide energy range were studied. Excess emission and absorption at approximately 6 to 7 kiloelectron volts in the spectra of supernova remnants, binary X-ray sources, and clusters of galaxies were observed. A gas scintillation proportional counter (GSPC) will be used as the detector system. In the gas scintillator the principal limitation is due to the statistics of the initial ionization process only.

  20. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... holds the x-ray film or image recording plate . Sometimes the x-ray is taken with the ... an x-ray film holder or image recording plate is placed beneath the patient. top of page ...

  1. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... the limitations of Bone X-ray (Radiography)? What is Bone X-ray (Radiography)? An x-ray (radiograph) ... diagnosis and disease management. top of page How is the procedure performed? The technologist, an individual specially ...

  2. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... holds the x-ray film or image recording plate . Sometimes the x-ray is taken with the ... an x-ray film holder or image recording plate is placed beneath the patient. top of page ...

  3. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... drawer under the table holds the x-ray film or image recording plate . Sometimes the x-ray ... extended over the patient while an x-ray film holder or image recording plate is placed beneath ...

  4. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... that might interfere with the x-ray images. Women should always inform their physician and x-ray ... Safety page for more information about radiation dose. Women should always inform their physician or x-ray ...

  5. X-ray absorption spectra of nucleotides (AMP, GMP, and CMP) in liquid water solutions near the nitrogen K-edge

    Science.gov (United States)

    Ukai, Masatoshi; Yokoya, Akinari; Fujii, Kentaro; Saitoh, Yuji

    2010-07-01

    The X-ray absorption of nucleotides (adenosine-5'-monophosphate, guanosine 5'-monophosphate, and cytidine 5'-monophosphate) are measured in both water solutions and thin solid films at X-ray energies near the nitrogen K-edge in the 'water-window' region. Each spectrum corresponds to the selective excitation of a nucleobase site in a nucleotide, and thus has features similar to the spectrum of the corresponding nucleobase. An additional new peak in the energy region of the nitrogen 1s → π* resonance is observed for each nucleotide. No significant difference between the water solutions and thin solid films is found, which might be attributable to the hydrophobic properties of a nucleobase in a nucleotide.

  6. X-ray spectral properties of accretion discs in X-ray binaries

    Energy Technology Data Exchange (ETDEWEB)

    White, N.E.; Stella, L.; Parmar, A.N.

    1988-01-01

    Exosat observations are used to compare the spectral properties of the persistent emission from a number of X-ray burst sources, high-luminosity low-mass X-ray binaries (LMXRB) and galactic black hole candidates with various models for X-ray emission from an accretion disk surrounding a compact object in a binary system. It is shown that only a Comptonization model provides a good fit to all of the spectra considered. The fits to the spectra of the high-luminosity LMXRB systems necessitate an additional blackbody component with a luminosity 16 to 34 percent that from the Comptonized component. 82 references.

  7. X-ray Pulsars

    CERN Document Server

    Walter, Roland

    2016-01-01

    X-ray pulsars shine thanks to the conversion of the gravitational energy of accreted material to X-ray radiation. The accretion rate is modulated by geometrical and hydrodynamical effects in the stellar wind of the pulsar companions and/or by instabilities in accretion discs. Wind driven flows are highly unstable close to neutron stars and responsible for X-ray variability by factors $10^3$ on time scale of hours. Disk driven flows feature slower state transitions and quasi periodic oscillations related to orbital motion and precession or resonance. On shorter time scales, and closer to the surface of the neutron star, X-ray variability is dominated by the interactions of the accreting flow with the spinning magnetosphere. When the pulsar magnetic field is large, the flow is confined in a relatively narrow accretion column, whose geometrical properties drive the observed X-ray emission. In low magnetized systems, an increasing accretion rate allows the ignition of powerful explosive thermonuclear burning at t...

  8. Towards brilliant, compact x-ray sources: a new x-ray photonic device

    Science.gov (United States)

    Scherer, Brian; Mandal, Sudeep; Salisbury, Joshua; Edic, Peter; Hopkins, Forrest; Lee, Susanne M.

    2017-05-01

    General Electric has designed an innovative x-ray photonic device that concentrates a polychromatic beam of diverging x-rays into a less divergent, parallel, or focused x-ray beam. The device consists of multiple, thin film multilayer stacks. X-rays incident on a given multilayer stack propagate within a high refractive index transmission layer while undergoing multiple total internal reflections from a novel, engineered multilayer containing materials of lower refractive index. Development of this device could lead to order-of-magnitude flux density increases, over a large broadband energy range from below 20 keV to above 300 keV. In this paper, we give an overview of the device and present GE's progress towards fabricating prototype devices.

  9. Two new Intermediate Polars with a soft X-ray component

    CERN Document Server

    Anzolin, G; Bonnet-Bidaud, J -M; Mouchet, M; Gänsicke, B T; Matt, G; Mukai, K

    2008-01-01

    We analyze the first X-ray observations with XMM-Newton of RXS J070407.9+262501 and 1RXS 180340.0+401214, in order to characterize their broad-band temporal and spectral properties, also in the UV/optical domain, and to confirm them as Intermediate Polars. For both objects, we performed a timing analysis of the X-ray and UV/optical light curves to detect the white dwarf spin pulsations and study their energy dependence. For 1RXS 180340.0+401214 we also analyzed optical spectroscopic data to determine the orbital period. X-ray spectra were analyzed in the 0.2-10.0 keV range to characterize the emission properties of both sources. We find that the X-ray light curves of both systems are energy dependent and are dominated, below 3-5 keV, by strong pulsations at the white dwarf rotational periods (480 s for 1RXS J070407.9+262501 and 1520.5 s for 1RXS 180340.0+401214). In 1RXS 180340.0+401214 we also detect an X-ray beat variability at 1697 s which, together with our new optical spectroscopy, favours an orbital per...

  10. Mass attenuation coefficient (μ/ρ), effective atomic number (Z{sub eff}) and measurement of x-ray energy spectra using based calcium phosphate biomaterials: a comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes Z, M. A.; Da Silva, T. A.; Nogueira, M. S. [Centro de Desenvolvimento da Tecnologia Nuclear / CNEN, Pte. Antonio Carlos 6627, Belo Horizonte 31270-901, Minas Gerais (Brazil); Goncalves Z, E., E-mail: madelon@cdtn.br [Pontifice Catholic University of Minas Gerais, Av. Dom Jose Gaspar 500, Belo Horizonte 30535-901, Minas Gerais (Brazil)

    2015-10-15

    In dentistry, alveolar bone regeneration procedures using based calcium phosphate biomaterials have been shown effective. However,there are not reports in the literature of studies the interaction of low energy radiation in these biomaterials used as attenuator and not being then allowed a comparison between the theoretical values and experimental.The objective of this study was to determine the interaction of radiation parameters of four dental biomaterials - BioOss, Cerasorb M Dental, Straumann Boneceramic and Osteogen for diagnostic radiology qualities. As a material and methods, the composition of the biomaterials was determined by the analytical techniques. The samples with 0.181 cm to 0,297 cm thickness were experimentally used as attenuators for the measurement of the transmitted X-rays spectra in X-ray equipment with 50 to 90 kV range by spectrometric system comprising the Cd Te detector. After this procedure, the mass attenuation coefficient, the effective atomic number were determined and compared between all the specimens analyzed, using the program WinXCOM in the range of 10 to 200 keV. In all strains examined observed that the energy spectrum of x-rays transmitted through the BioOss has the mean energy slightly smaller than the others biomaterials for close thickness. The μ/ρ and Z{sub eff} of the biomaterials showed its dependence on photon energy and atomic number of the elements of the material analyzed. It is concluded according to the methodology employed in this study that the measurements of x-ray spectrum, μ/ρ and Z{sub eff} using biomaterials as attenuators confirmed that the thickness, density, composition of the samples, the incident photon energy are factors that determine the characteristics of radiation in a tissue or equivalent material. (Author)

  11. The X-ray nova GRS 1739-278 near the Galactic center

    Science.gov (United States)

    Borozdin, K. N.; Revnivtsev, M. G.; Trudolyubov, S. P.; Aleksandrovich, N. L.; Sunyaev, R. A.; Skinner, G. K.

    1998-07-01

    The soft X-ray nova GRS 1739-278 flared up in 1996 near the Galactic center. We present the observations of this interesting source, a black-hole candidate, with the instruments on board the Mir-Kvant module and the RXTE satellite. The TTM data allow the spectrum of the X-ray nova to be studied during the rise in its brightness. The source's spectrum in this period is satisfactorily described by a power law with a gradually increasing index. The RXTE spectra after the source passed its maximum brightness have the appearance that is typical of the high and very high states of black-hole candidates; they are described by a two-component model. The broad-band spectra of the source are discussed in terms of the processes that proceed near an accreting black hole in a binary system.

  12. The X-ray Nova GRS 1739-278 near the Galactic Center

    CERN Document Server

    Borozdin, K N; Trudolyubov, S P; Aleksandrovich, N L; Sunyaev, R A; Skinner, G K

    1999-01-01

    The soft X-ray nova GRS 1739-278 flared up in 1996 near the Galactic center. We present the observations of this interesting source, a black-hole candidate, with the instruments on board the Mir-Kvant module and the RXTE satellite. The TTM data allow the spectrum of the X-ray nova to be studied during the rise in its brightness. The source's spectrum in this period is satisfactorily described by a power law with a gradually increasing index. The RXTE spectra after the source passed its maximum brightness have the appearance that is typical of the high and ultrahigh states of black-hole candidates; they are described by a two-component model. The broad-band spectra of the source are discussed in terms of the processes that proceed near an accreting black hole in a binary system.

  13. X-ray Emission from Solar Flares

    Indian Academy of Sciences (India)

    Rajmal Jain; Malini Aggarwal; Raghunandan Sharma

    2008-03-01

    Solar X-ray Spectrometer (SOXS), the first space-borne solar astronomy experiment of India was designed to improve our current understanding of X-ray emission from the Sun in general and solar flares in particular. SOXS mission is composed of two solid state detectors, viz., Si and CZT semiconductors capable of observing the full disk Sun in X-ray energy range of 4–56 keV. The X-ray spectra of solar flares obtained by the Si detector in the 4–25 keV range show evidence of Fe and Fe/Ni line emission and multi-thermal plasma. The evolution of the break energy point that separates the thermal and non-thermal processes reveals increase with increasing flare plasma temperature. Small scale flare activities observed by both the detectors are found to be suitable to heat the active region corona; however their location appears to be in the transition region.

  14. Local structures and electronic band states of α−Fe2O3 polycrystalline particles in the glazes of the HIZEN celadons produced in the Edo period of Japan, by means of X-ray absorption spectra (II)

    OpenAIRE

    Hidaka, M; Ohashi, K.; R. P. Wijesundera; L. S. R. Kumara; Sugihara, S.; Momoshima,N.; Kubuki,S.; Sung,N. E.

    2011-01-01

    HIZEN celadon glazes produced in 1630's to 1790's (Edo period, Japan) have been investigated by means of X-ray absorption spectra (XAS) near a Fe-K edge by using synchrotron radiation and a Mössbauer spectrum. The XAS suggest that the local structure around Fe2O3 fine powders is slightly different between the Izumiyama ceramics of mainly the Quartz-SiO2 and Ohkawachi ceramics of mainly the feldspar of (K,Na)Si3O8 (Sanidine), and that the glazes of the HIZEN celadons include the Fe2O3 fine pow...

  15. X-Ray Protection

    Science.gov (United States)

    1955-01-01

    15,000. • When developed In Kodak liquid X-ray developer for 5 min at a temperature of 200 C. b Film sensitivities vary with photon energy by the...for example temporomandibular -joint exposures where a skin dose of 25 r or more may be obtained during a single exposure with 65 kvp, 1.5 mm aluminum...communication. W. J. Updegrave, Temporomandibular articulation-X-ray examina- tion, Dental Radiography and Photography 26, No. 3, 41 (1953). H. 0. Wyckoff, R. J

  16. X-ray Reflection

    Science.gov (United States)

    Fabian, A. C.; Ross, R. R.

    2010-12-01

    Material irradiated by X-rays produces backscattered radiation which is commonly known as the Reflection Spectrum. It consists of a structured continuum, due at high energies to the competition between photoelectric absorption and electron scattering enhanced at low energies by emission from the material itself, together with a complex line spectrum. We briefly review the history of X-ray reflection in astronomy and discuss various methods for computing the reflection spectrum from cold and ionized gas, illustrated with results from our own work reflionx. We discuss how the reflection spectrum can be used to obtain the geometry of the accretion flow, particularly the inner regions around black holes and neutron stars.

  17. Electronic structure, X-ray spectra and magnetic properties of nonstoichiometric LiCoO sub 2 sub - subdelta and Na sub x CoO sub 2 oxides

    CERN Document Server

    Galakhov, V R; Karelina, V V; Kellerman, D G; Gorshkov, V S; Nojmann, M

    2002-01-01

    One studied magnetic susceptibility, X-ray photoelectron and X-ray emission spectra of LiCoO sub 2 sub - subdelta and Na sub x CoO sub 2 nonstoichiometric oxides. One analyzed structures of LiCoO sub 2 valent band. Ob the basis of O K alpha-spectra of emission measuring one determined hole concentration in LiNiO sub 2 and LiCoO sub 2 oxygen 2p-band. Measurements of Co 2p- and Co 3s-photoelectron spectra have shown that Co sup 3 sup + ions are in S = 0 low-spin state. In LiCoO sub 2 sub - subdelta reduced oxides oxygen deficit causes formation of cobalt bivalent ions. Deficit of alkali metal in Na sub x CoO sub 2 results in hole formation in oxygen 2p-band not varying d sup 6 electron configuration of ground state of cobalt ions

  18. Panoramic Dental X-Ray

    Science.gov (United States)

    ... Physician Resources Professions Site Index A-Z Panoramic Dental X-ray Panoramic dental x-ray uses a very small dose of ... x-ray , is a two-dimensional (2-D) dental x-ray examination that captures the entire mouth ...

  19. The properties of cross-correlation and spectra of the low-mass X-ray binary 4U 1608-52

    CERN Document Server

    Lei, Ya-Juan; Qu, Jin-Lu; Zhang, Hao-Tong; Li, Zhi-Bing; Zhang, Cheng-Min; Zhao, Yong-Heng

    2013-01-01

    With {\\it RXTE} data, we analyzed the cross-correlation function between the soft and hard X-rays of the transient atoll source 4U 1608-52. We found anti-correlations in three outbursts occurred in 1998, 2002 and 2010, and significant time lags of several hundreds of seconds in the latter two outbursts. Our results show no correlation between the soft and hard X-rays in the island state, and a dominated positive correlation in the lower banana state. Anti-correlations are presented at the upper banana state for the outburst of 2010 and at the lower left banana states for the other two outbursts. So far for atoll sources the cross-correlation has been studied statistically only for 4U 1735-44, where anti-correlations showed up in the upper banana state. Here our investigation upon 4U 1608-52 provides a similar result in its 2010 outburst. In addition, we notice that the luminosities in the upper banana of 1998 and 2002 outbursts are about 1.5 times that of 2010 outburst whose luminosity in the upper banana is ...

  20. Femtosecond X-ray magnetic circular dichroism absorption spectroscopy at an X-ray free electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Higley, Daniel J., E-mail: dhigley@stanford.edu; Yuan, Edwin [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Hirsch, Konstantin; Dakovski, Georgi L.; Jal, Emmanuelle; Lutman, Alberto A.; Coslovich, Giacomo; Hart, Philip; Hoffmann, Matthias C.; Mitra, Ankush; Moeller, Stefan; Ohldag, Hendrik; Seaberg, Matthew; Stöhr, Joachim; Nuhn, Heinz-Dieter; Reid, Alex H.; Dürr, Hermann A.; Schlotter, William F. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Liu, Tianmin; MacArthur, James P. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Physics, Stanford University, Stanford, California 94305 (United States); and others

    2016-03-15

    X-ray magnetic circular dichroism spectroscopy using an X-ray free electron laser is demonstrated with spectra over the Fe L{sub 3,2}-edges. The high brightness of the X-ray free electron laser combined with high accuracy detection of incident and transmitted X-rays enables ultrafast X-ray magnetic circular dichroism studies of unprecedented sensitivity. This new capability is applied to a study of all-optical magnetic switching dynamics of Fe and Gd magnetic sublattices in a GdFeCo thin film above its magnetization compensation temperature.

  1. X-ray echo spectroscopy (Conference Presentation)

    Science.gov (United States)

    Shvyd'ko, Yuri V.

    2016-09-01

    X-ray echo spectroscopy, a counterpart of neutron spin-echo, was recently introduced [1] to overcome limitations in spectral resolution and weak signals of the traditional inelastic x-ray scattering (IXS) probes. An image of a point-like x-ray source is defocused by a dispersing system comprised of asymmetrically cut specially arranged Bragg diffracting crystals. The defocused image is refocused into a point (echo) in a time-reversal dispersing system. If the defocused beam is inelastically scattered from a sample, the echo signal acquires a spatial distribution, which is a map of the inelastic scattering spectrum. The spectral resolution of the echo spectroscopy does not rely on the monochromaticity of the x-rays, ensuring strong signals along with a very high spectral resolution. Particular schemes of x-ray echo spectrometers for 0.1-meV and 0.02-meV ultra-high-resolution IXS applications (resolving power > 10^8) with broadband 5-13 meV dispersing systems will be presented featuring more than 1000-fold signal enhancement. The technique is general, applicable in different photon frequency domains. [1.] Yu. Shvyd'ko, Phys. Rev. Lett. 116, accepted (2016), arXiv:1511.01526.

  2. Chest X-Ray

    Medline Plus

    Full Text Available ... Therapy November 8 is the International Day of Radiology (IDoR) Radiology and You Sponsored by Image/Video Gallery Your Radiologist Explains Chest X-ray Transcript Welcome to Radiology Info dot org! Hello, I’m Dr. Geoffrey ...

  3. Science Objectives for an X-Ray Microcalorimeter Observing the Sun

    CERN Document Server

    Laming, J Martin; Alexander, D; Aschwanden, M; Bailey, C; Bandler, S; Bookbinder, J; Bradshaw, S; Brickhouse, N; Chervenak, J; Christe, S; Cirtain, J; Cranmer, S; Deiker, S; DeLuca, E; Del Zanna, G; Dennis, B; Doschek, G; Eckart, M; Fludra, A; Finkbeiner, F; Grigis, P; Harrison, R; Ji, L; Kankelborg, C; Kashyap, V; Kelly, D; Kelley, R; Kilbourne, C; Klimchuk, J; Ko, Y -K; Landi, E; Linton, M; Longcope, D; Lukin, V; Mariska, J; Martinez-Galarce, D; Mason, H; McKenzie, D; Osten, R; Peres, G; Pevtsov, A; Porter, K Phillips F S; Rabin, D; Rakowski, C; Raymond, J; Reale, F; Reeves, K; Sadleir, J; Savin, D; Schmelz, J; Smith, R K; Smith, S; Stern, R; Sylwester, J; Tripathi, D; Ugarte-Urra, I; Young, P; Warren, H; Wood, B

    2010-01-01

    We present the science case for a broadband X-ray imager with high-resolution spectroscopy, including simulations of X-ray spectral diagnostics of both active regions and solar flares. This is part of a trilogy of white papers discussing science, instrument (Bandler et al. 2010), and missions (Bookbinder et al. 2010) to exploit major advances recently made in transition-edge sensor (TES) detector technology that enable resolution better than 2 eV in an array that can handle high count rates. Combined with a modest X-ray mirror, this instrument would combine arcsecondscale imaging with high-resolution spectra over a field of view sufficiently large for the study of active regions and flares, enabling a wide range of studies such as the detection of microheating in active regions, ion-resolved velocity flows, and the presence of non-thermal electrons in hot plasmas. It would also enable more direct comparisons between solar and stellar soft X-ray spectra, a waveband in which (unusually) we currently have much b...

  4. The properties of cross-correlation and spectra of the low-mass X-ray binary 4U 1608-52

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Ya-Juan; Yuan, Hai-Long; Dong, Yi-Qiao; Zhang, Hao-Tong; Zhang, Cheng-Min; Zhao, Yong-Heng [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Zhang, Shu; Qu, Jin-Lu [Particle Astrophysics Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Wang, Ya-Nan; Li, Zhi-Bing, E-mail: leiyjcwmy@163.com [Xinjiang Astronomical Observatory, Chinese Academy of Sciences, 150, Science 1-Street, Urumqi, Xinjiang 830011 (China)

    2014-03-01

    With RXTE data, we analyzed the cross-correlation function between the soft and hard X-rays of the transient atoll source 4U 1608-52. We found anti-correlations in three outbursts occurred in 1998, 2002, and 2010, and we found significant time lags of several hundreds of seconds in the latter two outbursts. Our results show no correlation between the soft and hard X-rays in the extreme island state and a dominated positive correlation in the lower banana state. Anti-correlations are presented at the upper banana state for the outburst of 2010 and at the island and the lower left banana states for the other two outbursts. So far for atoll sources, the cross-correlation has been studied statistically only for 4U 1735-44, where anti-correlations showed up in the upper banana state. Here our investigation on 4U 1608-52 provides a similar result in its 2010 outburst. In addition, we notice that the luminosities in the upper banana of the 1998 and 2002 outbursts are about 1.5 times that of the 2010 outburst whose luminosity in the upper banana is close to that of 4U 1735-44. The results suggest that the states in the color-color diagram of a source could be correlated with the luminosity of the source. A further spectral analysis during the 2010 outburst is also shown, which suggests that the disk can be a little truncated in the upper banana. The feature on the upper banana is similar to the previous results of the flaring branch in Z sources.

  5. Rapid acquisition of 14N solid-state NMR spectra with broadband cross polarization.

    Science.gov (United States)

    Harris, Kristopher J; Veinberg, Stanislav L; Mireault, Christopher R; Lupulescu, Adonis; Frydman, Lucio; Schurko, Robert W

    2013-11-25

    Nitrogen is an element of utmost importance in chemistry, biology and materials science. Of its two NMR-active isotopes, (14)N and (15)N, solid-state NMR (SSNMR) experiments are rarely conducted upon the former, due to its low gyromagnetic ratio (γ) and broad powder patterns arising from first-order quadrupolar interactions. In this work, we propose a methodology for the rapid acquisition of high quality (14)N SSNMR spectra that is easy to implement, and can be used for a variety of nitrogen-containing systems. We demonstrate that it is possible to dramatically enhance (14)N NMR signals in spectra of stationary, polycrystalline samples (i.e., amino acids and active pharmaceutical ingredients) by means of broadband cross polarization (CP) from abundant nuclei (e.g., (1)H). The BRoadband Adiabatic INversion Cross-Polarization (BRAIN-CP) pulse sequence is combined with other elements for efficient acquisition of ultra-wideline SSNMR spectra, including Wideband Uniform-Rate Smooth-Truncation (WURST) pulses for broadband refocusing, Carr-Purcell Meiboom-Gill (CPMG) echo trains for T2-driven S/N enhancement, and frequency-stepped acquisitions. The feasibility of utilizing the BRAIN-CP/WURST-CPMG sequence is tested for (14)N, with special consideration given to (i) spin-locking integer spin nuclei and maintaining adiabatic polarization transfer, and (ii) the effects of broadband polarization transfer on the overlapping satellite transition patterns. The BRAIN-CP experiments are shown to provide increases in signal-to-noise ranging from four to ten times and reductions of experimental times from one to two orders of magnitude compared to analogous experiments where (14)N nuclei are directly excited. Furthermore, patterns acquired with this method are generally more uniform than those acquired with direct excitation methods. We also discuss the proposed method and its potential for probing a variety of chemically distinct nitrogen environments.

  6. X-ray Emission of Hollow Atoms

    Institute of Scientific and Technical Information of China (English)

    ZhaoYongtao; XiaoGuoqing; ZhangXiaoan; YangZhihu; ChenXimeng; ZhangYanping

    2003-01-01

    We have systematically investigated the X-rays emission of hollow atoms (HA) which formed in the interaction of highly charged ions with a variety of solid surfaces at the atomic physics experimental setup of IMP. The X-ray spectra were measured by Si(Li) detectors with effective energy ranging from 1 keV to 60 keV. The results show that, the X-ray emission from the formed HA is closely correlated with the charge state of the projectile ions, and weakly correlated with the velocity of the projectile ions. For example, it was found that when Ar18+ ions interact with Be-target, the yield of K X-ray with character energy of 3.0 keV is 7.2×10-3 per ion, which is two times and 5 order of magnitude higher than those in the interactions of Ar17+ and Ar16+ ions respectively. When Ar15+ ions interact with the same targets, the Argon K X-ray would be too feeble to be detected. The X-ray yield with single ion in this experiment can be represented by the following equation,

  7. The SAS-3 X-ray observatory

    Science.gov (United States)

    Mayer, W. F.

    1975-01-01

    The experiment section of the Small Astronomy Satellite-3 (SAS-3) launched in May 1975 is an X-ray observatory intended to determine the location of bright X-ray sources to an accuracy of 15 arc-seconds; to study a selected set of sources over a wide energy range, from 0.1 to 55 keV, while performing very specific measurements of the spectra and time variability of known X-ray sources; and to monitor the sky continuously for X-ray novae, flares, and unexpected phenomena. The improvements in SAS-3 spacecraft include a clock accurate to 1 part in 10 billion, rotatable solar panels, a programmable data format, and improved nutation damper, a delayed command system, improved magnetic trim and azimuth control systems. These improvements enable SAS-3 to perform three-axis stabilized observations of any point on the celestial sphere at any time of the year. The description of the experiment section and the SAS-3 operation is followed by a synopsis of scientific results obtained from the observations of X-ray sources, such as Vela X-1 (supposed to be an accreting neutron star), a transient source of hard X-ray (less than 36 min in duration) detected by SAS-3, the Crab Nebula pulsar, the Perseus cluster of galaxies, and the Vela supernova remnant.

  8. Sensitivity Limits of Deep Average Broadband Microwave and Mm-Wave Spectra

    Science.gov (United States)

    Muckle, Matt T.; Zaleski, Daniel P.; Steber, Amanda; Harris, Brent; Pate, Brooks H.

    2012-06-01

    High-speed digitizers have enabled the field of broadband molecular rotational spectroscopy at microwave-to-THz frequencies. Improvements in data throughput from these digitizers makes it feasible to perform deep averages (often more than 1 million time-domain averages of the free induction decay) to increase the measurement sensitivity. The use of broadband signal detection introduces new issues that are key for determining the practical sensitivity limits of these spectrometers. The practical limit on spectrometer sensitivity is often set by the number of spurious signals that are generated by the molecular signals themselves. For example, in cases where the molecular signals are down converted prior to digitization, the spectral purity of the local oscillator is crucial with spurious frequencies introducing spectral images. It is also possible to generate new local oscillator frequencies within the broadband mixers typically used in the broadband down conversion. A second issue it the potential for a vast number of intermodulation (IM) spurious signals resulting from the beating of two strong molecular transitions. This beat frequency can subsequently modulate all other molecular signals adding sidebands to all transitions at the beat frequency of the transition pair. This talk will summarize our experience with the spurious signal levels coming from these effects and the strategies we have adopted to minimize spurious signals in spectra where high sensitivity is necessary.

  9. X-Ray Astronomy

    Science.gov (United States)

    Wu, S. T.

    2000-01-01

    Dr. S. N. Zhang has lead a seven member group (Dr. Yuxin Feng, Mr. XuejunSun, Mr. Yongzhong Chen, Mr. Jun Lin, Mr. Yangsen Yao, and Ms. Xiaoling Zhang). This group has carried out the following activities: continued data analysis from space astrophysical missions CGRO, RXTE, ASCA and Chandra. Significant scientific results have been produced as results of their work. They discovered the three-layered accretion disk structure around black holes in X-ray binaries; their paper on this discovery is to appear in the prestigious Science magazine. They have also developed a new method for energy spectral analysis of black hole X-ray binaries; four papers on this topics were presented at the most recent Atlanta AAS meeting. They have also carried Monte-Carlo simulations of X-ray detectors, in support to the hardware development efforts at Marshall Space Flight Center (MSFC). These computation-intensive simulations have been carried out entirely on the computers at UAH. They have also carried out extensive simulations for astrophysical applications, taking advantage of the Monte-Carlo simulation codes developed previously at MSFC and further improved at UAH for detector simulations. One refereed paper and one contribution to conference proceedings have been resulted from this effort.

  10. X-ray lithography masking

    Science.gov (United States)

    Smith, Henry I. (Inventor); Lim, Michael (Inventor); Carter, James (Inventor); Schattenburg, Mark (Inventor)

    1998-01-01

    X-ray masking apparatus includes a frame having a supporting rim surrounding an x-ray transparent region, a thin membrane of hard inorganic x-ray transparent material attached at its periphery to the supporting rim covering the x-ray transparent region and a layer of x-ray opaque material on the thin membrane inside the x-ray transparent region arranged in a pattern to selectively transmit x-ray energy entering the x-ray transparent region through the membrane to a predetermined image plane separated from the layer by the thin membrane. A method of making the masking apparatus includes depositing back and front layers of hard inorganic x-ray transparent material on front and back surfaces of a substrate, depositing back and front layers of reinforcing material on the back and front layers, respectively, of the hard inorganic x-ray transparent material, removing the material including at least a portion of the substrate and the back layers of an inside region adjacent to the front layer of hard inorganic x-ray transparent material, removing a portion of the front layer of reinforcing material opposite the inside region to expose the surface of the front layer of hard inorganic x-ray transparent material separated from the inside region by the latter front layer, and depositing a layer of x-ray opaque material on the surface of the latter front layer adjacent to the inside region.

  11. X-Ray Calorimeter Arrays for Astrophysics

    Science.gov (United States)

    Kilbourne, Caroline A.

    2009-01-01

    High-resolution x-ray spectroscopy is a powerful tool for studying the evolving universe. The grating spectrometers on the XMM and Chandra satellites started a new era in x-ray astronomy, but there remains a need for instrumentation that can provide higher spectral resolution with high throughput in the Fe-K band (around 6 keV) and can enable imaging spectroscopy of extended sources, such as supernova remnants and galaxy clusters. The instrumentation needed is a broad-band imaging spectrometer - basically an x-ray camera that can distinguish tens of thousands of x-ray colors. The potential benefits to astrophysics of using a low-temperature calorimeter to determine the energy of an incident x-ray photon via measurement of a small change in temperature was first articulated by S. H. Moseley over two decades ago. In the time since, technological progress has been steady, though full realization in an orbiting x-ray telescope is still awaited. A low-temperature calorimeter can be characterized by the type of thermometer it uses, and three types presently dominate the field. The first two types are temperature-sensitive resistors - semiconductors in the metal-insulator transition and superconductors operated in the superconducting-normal transition. The third type uses a paramagnetic thermometer. These types can be considered the three generations of x-ray calorimeters; by now each has demonstrated a resolving power of 2000 at 6 keV, but only a semiconductor calorimeter system has been developed to spaceflight readiness. The Soft X-ray Spectrometer on Astro-H, expected to launch in 2013, will use an array of silicon thermistors with I-IgTe x-ray absorbers that will operate at 50 mK. Both the semiconductor and superconductor calorimeters have been implemented in small arrays, kilo-pixel arrays of the superconducting calorimeters are just now being produced, and it is anticipated that much larger arrays will require the non-dissipative advantage of magnetic thermometers.

  12. XMM-Newton X-Ray Observation of Jupiter

    Science.gov (United States)

    Waite, J. Hunter

    2005-01-01

    Soft X-ray emission has been observed from the disk of both Jupiter and Saturn as well as from the auroral regions of these planets. The low-latitude disk emission as observed by ROSAT, the Chandra X-Ray Observatory, and XMM-Newton appears to be uniformly distributed across the disk and to be correlated with solar activity. These characteristics suggest that the disk x-rays are produced by: (1) the elastic scattering of solar X-rays by atmospheric neutrals and (2) the absorption of solar X-rays in the carbon K-shell followed by fluorescent emission. The carbon atoms are found in methane molecules located below the homopause. In this paper we present the results of calculations of the scattering albedo for soft x-rays. We also show the calculated x-ray intensity for a range of atmospheric abundances for Jupiter and Saturn and for a number of solar irradiance spectra. The model calculations are compared with recent x-ray observations of Jupiter and Saturn. We conclude that the emission of soft x-rays from the disks of Jupiter and Saturn can be largely explained by the scattering and fluorescence of soft x-rays. We suggest that measured x-ray intensities from the disk regions of Jupiter

  13. X-ray spectroscopy of manganese clusters

    Energy Technology Data Exchange (ETDEWEB)

    Grush, M.M. [Univ. of California, Davis, CA (United States). Dept. of Applied Science]|[Lawrence Berkeley National Lab., CA (United States). Energy and Environment Div.

    1996-06-01

    Much of this thesis represents the groundwork necessary in order to probe Mn clusters more productively than with conventional Mn K-edge XAS and is presented in Part 1. Part 2 contains the application of x-ray techniques to Mn metalloproteins and includes a prognosis at the end of each chapter. Individual Mn oxidation states are more readily distinguishable in Mn L-edge spectra. An empirical mixed valence simulation routine for determining the average Mn oxidation state has been developed. The first Mn L-edge spectra of a metalloprotein were measured and interpreted. The energy of Mn K{beta} emission is strongly correlated with average Mn oxidation state. K{beta} results support oxidation states of Mn(III){sub 2}(IV){sub 2} for the S{sub 1} state of Photosystem II chemical chemically reduced preparations contain predominantly Mn(II). A strength and limitation of XAS is that it probes all of the species of a particular element in a sample. It would often be advantageous to selectively probe different forms of the same element. The first demonstration that chemical shifts in x-ray fluorescence energies can be used to obtain oxidation state-selective x-ray absorption spectra is presented. Spin-dependent spectra can also be used to obtain a more simplified picture of local structure. The first spin-polarized extended x-ray absorption fine structure using Mn K{beta} fluorescence detection is shown.

  14. Unveiling the Structure of Active Galactic Nuclei with Hard X-ray Spectroscopy

    Science.gov (United States)

    Balokovic, Mislav

    Despite the long history of studies of active galactic nuclei (AGN), details of the structure of the accretion flow onto supermassive black holes are far from clear. Work presented in this thesis is directed at unveiling properties of AGN structure through broadband X-ray spectroscopy, with particular emphasis on the hard X-ray band (photon energies above 10 keV). With its unprecedented sensitivity in this energy band, the NuSTAR telescope provides the key observational diagnostics of the properties of the AGN X-ray source, the corona, and the surrounding gas in the accretion disk, the broad-line region, and the torus. The first study presented in this thesis focuses on measurements of the optical depth and the temperature of the plasma in the corona of an obscured AGN. Fitting theoretical spectral models for coronal emission to the NuSTAR data constrained these two basic physical parameters under the assumption of either spherical or disk-like geometry for the corona. The remainder of the thesis is dedicated to studies of the anisotropic obscuring structure broadly referred to as the torus. One of them is a case study of three heavily obscured AGN with spectra dominated by the X-ray light scattered and reprocessed in the torus, where it is possible to constrain one of the basic torus properties - its globally averaged column density. The following study presents the calculation of a new spectral model for reprocessing of the intrinsic X-ray continuum within the torus. Its added flexibility compared to previously available models allows for both the average column density of the torus and its covering factor to be constrained from broadband X-ray spectra of a wide variety of AGN. The final part of the thesis in based on a large survey of the local obscured AGN population performed with NuSTAR. Spectral modeling of more than a hundred individual AGN, including both old and new spectral models, is presented. From analyses of the X-ray data for a large and

  15. Cation profiling of passive films on stainless steel formed in sulphuric and acetic acid by deconvolution of angle-resolved X-ray photoelectron spectra

    Energy Technology Data Exchange (ETDEWEB)

    Högström, Jonas, E-mail: jhogstrom@gmail.com; Fredriksson, Wendy, E-mail: wendy.fredriksson@kemi.uu.se; Edstrom, Kristina, E-mail: kristina.edstrom@kemi.uu.se; Björefors, Fredrik, E-mail: fredrik.bjorefors@kemi.uu.se; Nyholm, Leif, E-mail: leif.nyholm@kemi.uu.se; Olsson, Claes-Olof A., E-mail: drclabbe@kth.se

    2013-11-01

    An approach for determining depth gradients of metal-ion concentrations in passive films on stainless steel using angle-resolved X-ray photoelectron spectroscopy (ARXPS) is described. The iterative method, which is based on analyses of the oxidised metal peaks, provides increased precision and hence allows faster ARXPS measurements to be carried out. The method was used to determine the concentration depth profiles for molybdenum, iron and chromium in passive films on 316L/EN 1.4432 stainless steel samples oxidised in 0.5 M H{sub 2}SO{sub 4} and acetic acid diluted with 0.02 M Na{sub 2}B{sub 4}O{sub 7} · 10H{sub 2}O and 1 M H{sub 2}O, respectively. The molybdenum concentration in the film is pin-pointed to the oxide/metal interface and the films also contained an iron-ion-enriched surface layer and a chromium-ion-dominated middle layer. Although films of similar composition and thickness (i.e., about 2 nm) were formed in the two electrolytes, the corrosion currents were found to be three orders of magnitude larger in the acetic acid solution. The differences in the layer composition, found for the two electrolytes as well as different oxidation conditions, can be explained based on the oxidation potentials of the metals and the dissolution rates of the different metal ions.

  16. Panoramic Dental X-Ray

    Science.gov (United States)

    ... Physician Resources Professions Site Index A-Z Panoramic Dental X-ray Panoramic dental x-ray uses a ... Your e-mail address: Personal message (optional): Bees: Wax: Notice: RadiologyInfo respects your privacy. Information entered here ...

  17. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... the body. X-rays are the oldest and most frequently used form of medical imaging. A bone ... bones. top of page How should I prepare? Most bone x-rays require no special preparation. You ...

  18. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... tissue shows up in shades of gray and air appears black. Until recently, x-ray images were ... position possible that still ensures x-ray image quality. top of page Who interprets the results and ...

  19. Soft X-ray Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Seely, John

    1999-05-20

    The contents of this report cover the following: (1) design of the soft x-ray telescope; (2) fabrication and characterization of the soft x-ray telescope; and (3) experimental implementation at the OMEGA laser facility.

  20. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... of page What are some common uses of the procedure? A bone x-ray is used to: ... and x-rays. top of page What does the equipment look like? The equipment typically used for ...

  1. Bone X-Ray (Radiography)

    Science.gov (United States)

    ... clothing that might interfere with the x-ray images. Women should always inform their physician and x-ray ... small burst of radiation that passes through the body, recording an image on photographic film or a special detector. Different ...

  2. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... standards used by radiology professionals. Modern x-ray systems have very controlled x-ray beams and dose control methods to minimize stray (scatter) radiation. This ensures ...

  3. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... current x-ray images for diagnosis and disease management. top of page How is the procedure performed? ... position possible that still ensures x-ray image quality. top of page Who interprets the results and ...

  4. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... Us News Physician Resources Professions Site Index A-Z X-ray (Radiography) - Bone Bone x-ray uses ... assess trauma patients in emergency departments. A CT scan can image complicated fractures, subtle fractures or dislocations. ...

  5. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... patient. top of page How does the procedure work? X-rays are a form of radiation like ... very controlled x-ray beams and dose control methods to minimize stray (scatter) radiation. This ensures that ...

  6. Abdomen X-Ray (Radiography)

    Science.gov (United States)

    ... Professions Site Index A-Z X-ray (Radiography) - Abdomen Abdominal x-ray uses a very small dose ... to produce pictures of the inside of the abdominal cavity. It is used to evaluate the stomach, liver, ...

  7. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... radiation like light or radio waves. X-rays pass through most objects, including the body. Once it ... organs, allow more of the x-rays to pass through them. As a result, bones appear white ...

  8. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... current x-ray images for diagnosis and disease management. top of page How is the procedure performed? ... position possible that still ensures x-ray image quality. top of page Who interprets the results and ...

  9. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... and x-rays. A Word About Minimizing Radiation Exposure Special care is taken during x-ray examinations ... patient's body not being imaged receive minimal radiation exposure. top of page What are the limitations of ...

  10. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... fracture. guide orthopedic surgery, such as spine repair/fusion, joint replacement and fracture reductions. look for injury, ... and Media Arthritis X-ray, Interventional Radiology and Nuclear Medicine Radiation Safety Images related to X-ray ( ...

  11. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... of page What are some common uses of the procedure? A bone x-ray is used to: ... and x-rays. top of page What does the equipment look like? The equipment typically used for ...

  12. Unveiling the intrinsic X-ray properties of broad absorption line quasars with a relatively unbiased sample

    Energy Technology Data Exchange (ETDEWEB)

    Morabito, Leah K.; Dai, Xinyu; Leighly, Karen M. [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States); Sivakoff, Gregory R. [Department of Physics, University of Alberta, CCIS 4-183 Edmonton, AB T6G 2E1 (Canada); Shankar, Francesco [School of Physics and Astronomy, University of Southampton, Southampton SO17 IBJ (United Kingdom)

    2014-05-01

    There is growing evidence of a higher intrinsic fraction of broad absorption line quasars (BALQSOs) than that obtained in optical surveys, on which most previous X-ray studies of BALQSOs have focused. Here we present Chandra observations of 18 BALQSOs at z ∼ 2, selected from a near-infrared (Two Micron All Sky Survey) sample, where the BALQSO fraction is likely to be close to the intrinsic fraction. We measure photon indices using the stacked spectra of the optically faint (i – K{sub s} ≥ 2.3 mag) and optically bright (i – K{sub s} < 2.3 mag) samples to be Γ ≅ 1.5-2.1. We constrain their intrinsic column density by modeling the X-ray fractional hardness ratio, finding a mean column density of 3.5 × 10{sup 22} cm{sup –2} assuming neutral absorption. We incorporate Sloan Digital Sky Survey optical measurements (rest frame UV) to study the broadband spectral index between the X-ray and UV bands, and compare this to a large sample of normal quasars. We estimate that the optically faint BALQSOs are X-ray weaker than the optically bright ones, and the entire sample of BALQSOs are intrinsically X-ray weak when compared to normal active galactic nuclei (AGNs). Correcting for magnification of X-ray emission via gravitational lensing by the central black hole viewed at large inclination angles makes these BALQSOs even more intrinsically X-ray weak. Finally, we estimate AGN kinetic feedback efficiencies of a few percent for an X-ray wind of 0.3c in high-ionization BALQSOs. Combined with energy carried by low-ionization BALQSOs and UV winds, the total kinetic energy in BALQSOs can be sufficient to provide AGN kinetic feedback required to explain the co-evolution between black holes and host galaxies.

  13. Iron-line and continuum variations in the XMM-Newton and Suzaku spectra of the neutron-star low-mass X-ray binary 4U 1636-53

    CERN Document Server

    Lyu, Ming; Sanna, Andrea; Homan, Jeroen; Belloni, Tomaso; Hiemstra, Beike

    2014-01-01

    We used six simultaneous XMM-Newton and Rossi X-ray Timing Explorer plus five Suzaku observations to study the continuum spectrum and the iron emission line in the neutron-star low-mass X-ray binary 4U 1636-53. We modelled the spectra with two thermal components (representing the accretion disc and boundary layer), a Comptonised component (representing a hot corona), and either a Gaussian or a relativistic line component to model an iron emission line at about 6.5 keV. For the relativistic line component we used either the diskline, laor or kyrline model, the latter for three different values of the spin parameter. The fitting results for the continuum are consistent with the standard truncated disc scenario. We also find that the flux and equivalent width of the iron line first increase and then decrease as the flux of the Comptonised component increases. This could be explained either by changes in the ionisation state of the accretion disc where the line is produced by reflection, or by light bending of th...

  14. X-Ray Exam: Hip

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Hip KidsHealth > For Parents > X-Ray Exam: Hip A A A What's in ... español Radiografía: cadera What It Is A hip X-ray is a safe and painless test that ...

  15. X-Ray Exam: Finger

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Finger KidsHealth > For Parents > X-Ray Exam: Finger A A A What's in ... español Radiografía: dedo What It Is A finger X-ray is a safe and painless test that ...

  16. X-Ray Exam: Foot

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Foot KidsHealth > For Parents > X-Ray Exam: Foot A A A What's in ... español Radiografía: pie What It Is A foot X-ray is a safe and painless test that ...

  17. X-Ray Exam: Wrist

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Wrist KidsHealth > For Parents > X-Ray Exam: Wrist A A A What's in ... español Radiografía: muñeca What It Is A wrist X-ray is a safe and painless test that ...

  18. X-Ray Exam: Ankle

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Ankle KidsHealth > For Parents > X-Ray Exam: Ankle A A A What's in ... español Radiografía: tobillo What It Is An ankle X-ray is a safe and painless test that ...

  19. X-Ray Exam: Pelvis

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Pelvis KidsHealth > For Parents > X-Ray Exam: Pelvis A A A What's in ... español Radiografía: pelvis What It Is A pelvis X-ray is a safe and painless test that ...

  20. X-Ray Exam: Forearm

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Forearm KidsHealth > For Parents > X-Ray Exam: Forearm A A A What's in ... español Radiografía: brazo What It Is A forearm X-ray is a safe and painless test that ...

  1. X-ray Crystallography Facility

    Science.gov (United States)

    2000-01-01

    Edward Snell, a National Research Council research fellow at NASA's Marshall Space Flight Center (MSFC), prepares a protein crystal for analysis by x-ray crystallography as part of NASA's structural biology program. The small, individual crystals are bombarded with x-rays to produce diffraction patterns, a map of the intensity of the x-rays as they reflect through the crystal.

  2. Tokamak Spectroscopy for X-Ray Astronomy

    Science.gov (United States)

    Fournier, Kevin B.; Finkenthal, M.; Pacella, D.; May, M. J.; Soukhanovskii, V.; Mattioli, M.; Leigheb, M.; Rice, J. E.

    2000-01-01

    This paper presents the measured x-ray and Extreme Ultraviolet (XUV) spectra of three astrophysically abundant elements (Fe, Ca and Ne) from three different tokamak plasmas. In every case, each spectrum touches on an issue of atomic physics that is important for simulation codes to be used in the analysis of high spectral resolution data from current and future x-ray telescopes. The utility of the tokamak as a laboratory test bed for astrophysical data is demonstrated. Simple models generated with the HULLAC suite of codes demonstrate how the atomic physics issues studied can affect the interpretation of astrophysical data.

  3. Experimental (X-ray, FT-IR and UV-vis spectra) and theoretical methods (DFT study) of (E)-3-methoxy-2-[(p-tolylimino)methyl]phenol.

    Science.gov (United States)

    Demircioğlu, Zeynep; Albayrak, Çiğdem; Büyükgüngör, Orhan

    2014-07-15

    A suitable single crystal of (E)-3-methoxy-2-[(p-tolylimino)methyl]phenol, formulated as C15H15N1O2, reveals that the structure is adopted to its E configuration about the azomethine C=N double bond. The compound adopts a enol-imine tautomeric form with a strong intramolecular O-H⋯N hydrogen bond. The single crystal X-ray diffraction analysis at 296K crystallizes in the monoclinic space group P21/c with a = 13.4791(11) Å, b = 6.8251(3) Å, c = 18.3561(15) Å, α = 90°, β = 129.296(5)°, γ = 90° and Z = 4. Comprehensive theoretical and experimental structural studies on the molecule have been carried out by FT-IR and UV-vis spectrometry. Optimized molecular structure and harmonic vibrational frequencies have been investigated by DFT/B3LYP method with 6-31G(d,p) basis set. Stability of the molecule, hyperconjugative interactions, charge delocalization and intramolecular hydrogen bond has been analyzed by using natural bond orbital (NBO) analysis. Electronic structures were discussed by TD-DFT method and the relocation of the electron density were determined. The energetic behavior of the title compound has been examined in solvent media using polarizable continuum model (PCM). Molecular electrostatic potential (MEP), Mulliken population method and natural population analysis (NPA) have been studied. Nonlinear optical (NLO) properties were also investigated. In addition, frontier molecular orbitals analysis have been performed from the optimized geometry. An ionization potential (I), electron affinity (A), electrophilicity index (ω), chemical potential (μ), electronegativity (χ), hardness (η), and softness (S), have been investigated.

  4. [X-ray diffraction spectrum of heroin].

    Science.gov (United States)

    Hu, X; Kan, J; Yuan, B

    1999-06-01

    In this paper, practical measured X-ray diffraction spectra of heroin and opium are given and the parameters of each diffraction peak of the heroin are listed. The heroin belongs to orthorhombic crystal system; the basic vectors of the primitive cell are: a = 8.003, b = 14.373, c = 16.092 x 10(-10) m. As compared with the standard spectra of pure heroin and sucrose, the main doped additive checked by us, is sugar affirmatively.

  5. SMM x ray polychromator

    Science.gov (United States)

    Saba, J. L. R.

    1993-01-01

    The objective of the X-ray Polychromator (XRP) experiment was to study the physical properties of solar flare plasma and its relation to the parent active region to understand better the flare mechanism and related solar activity. Observations were made to determine the temperature, density, and dynamic structure of the pre-flare and flare plasma as a function of wavelength, space and time, the extent to which the flare plasma departs from thermal equilibrium, and the variation of this departure with time. The experiment also determines the temperature and density structure of active regions and flare-induced changes in the regions.

  6. X-ray today

    Energy Technology Data Exchange (ETDEWEB)

    Neitzel, U. [Philips Medical Systems, Hamburg (Germany)

    2001-09-01

    The interest attracted by the new imaging modalities tends to overshadow the continuing importance of projection radiography and fluoroscopy. Nevertheless, projection techniques still represent by far the greatest proportion of diagnostic imaging examinations, and play an essential role in the growing number of advanced interventional procedures. This article describes some of the latest developments in X-ray imaging technology, using two products from the Philips range as examples: the Integris Allura cardiovascular system with 3D image reconstruction, and the BV Pulsera: a high-end, multi-functional mobile C-arm system with cardiac capabilities. (orig.)

  7. Handbook of X-Ray Astronomy

    Science.gov (United States)

    Arnaud, Keith A. (Editor); Smith, Randall K.; Siemiginowska, Aneta

    2011-01-01

    X-ray astronomy was born in the aftermath of World War II as military rockets were repurposed to lift radiation detectors above the atmosphere for a few minutes at a time. These early flights detected and studied X-ray emission from the Solar corona. The first sources beyond the Solar System were detected during a rocket flight in 1962 by a team headed by Riccardo Giaccom at American Science and Engineering, a company founded by physicists from MIT. The rocket used Geiger counters with a system designed to reduce non-X-ray backgrounds and collimators limiting the region of sky seen by the counters. As the rocket spun, the field of view (FOV) happened to pass over what was later found to be the brightest non-Solar X-ray source; later designated See X-1. It also detected a uniform background glow which could not be resolved into individual sources. A follow-up campaign using X-ray detectors with better spatial resolution and optical telescopes identified See X-1 as an interacting binary with a compact (neutron star) primary. This success led to further suborbital rocket flights by a number of groups. More X-ray binaries were discovered, as well as X-ray emission from supernova remnants, the radio galaxies M87 and Cygnus-A, and the Coma cluster. Detectors were improved and Geiger counters were replaced by proportional counters, which provided information about energy spectra of the sources. A constant challenge was determining precise positions of sources as only collimators were available.

  8. Calculation of conversion coefficients for air kerma to ambient dose equivalent using transmitted spectra of megavoltage X-rays through concrete.

    Science.gov (United States)

    Cordeiro, T P V; Silva, A X

    2012-12-01

    With the fast advancement of technology, (60)Co teletherapy units are largely being replaced with medical linear accelerators. In most cases, the linear accelerator tends to be installed in the same room in which the (60)Co teletherapy unit was previously placed. If in-depth structural remodelling is out of the question, high-density concrete is usually used to improve shielding against primary, scatter and leakage radiation originating in the new equipment. This work presents a study based on Monte Carlo simulations of the transmission of some clinical photon spectra (from 6, 10, 15, 18 and 25 MV accelerators) through concrete, considering two different densities. Concrete walls with thickness ranging from 0.70 to 2.0 m were irradiated with 30 cm×30 cm primary beam spectra. The results show that the thickness of the barrier decreases up to ∼65 % when barite (high-density concrete) is used instead of ordinary concrete. The average energies of primary and transmitted beam spectra were also calculated. In addition, conversion coefficients from air kerma to ambient dose equivalent, H*(d)/K(air), and air kerma to effective dose, E/K(air), for photon spectra from the transmitted spectra were calculated and compared. The results suggest that the 10-mm depth is not the best choice to represent the effective dose.

  9. Contact x-ray microscopy using Asterix

    Science.gov (United States)

    Conti, Aldo; Batani, Dimitri; Botto, Cesare; Masini, Alessandra; Bernardinello, A.; Bortolotto, Fulvia; Moret, M.; Poletti, G.; Piccoli, S.; Cotelli, F.; Lora Lamia Donin, C.; Stead, Anthony D.; Marranca, A.; Eidmann, Klaus; Flora, Francesco; Palladino, Libero; Reale, Lucia

    1997-10-01

    The use of a high energy laser source for soft x-ray contact microscopy is discussed. Several different targets were used and their emission spectra compared. The x-ray emission, inside and outside the Water Window, was characterized in detail by means of many diagnostics, including pin hole and streak cameras. Up to 12 samples holders per shot were exposed thanks to the large x-ray flux and the geometry of the interaction chamber. Images of several biological samples were obtained, including Chlamydomonas and Crethidia green algae, fish and boar sperms and Saccharomyces Cerevisiae yeast cells. A 50 nm resolution was reached on the images of boar sperm. Original information concerning the density of inner structures of Crethidia green algae were obtained.

  10. X-ray emission processes in stars

    CERN Document Server

    Testa, Paola

    2010-01-01

    A decade of X-ray stellar observations with Chandra and XMM-Newton has led to significant advances in our understanding of the physical processes at work in hot (magnetized) plasmas in stars and their immediate environment, providing new perspectives and challenges, and in turn the need for improved models. The wealth of high-quality stellar spectra has allowed us to investigate, in detail, the characteristics of the X-ray emission across the HR diagram. Progress has been made in addressing issues ranging from classical stellar activity in stars with solar-like dynamos (such as flares, activity cycles, spatial and thermal structuring of the X-ray emitting plasma, evolution of X-ray activity with age), to X-ray generating processes (e.g. accretion, jets, magnetically confined winds) that were poorly understood in the pre-Chandra/XMM-Newton era. I discuss the progress made in the study of high energy stellar physics and its impact in a wider astrophysical context, focusing on the role of spectral diagnostics no...

  11. X-ray lithography source

    Science.gov (United States)

    Piestrup, Melvin A.; Boyers, David G.; Pincus, Cary

    1991-01-01

    A high-intensity, inexpensive X-ray source for X-ray lithography for the production of integrated circuits. Foil stacks are bombarded with a high-energy electron beam of 25 to 250 MeV to produce a flux of soft X-rays of 500 eV to 3 keV. Methods of increasing the total X-ray power and making the cross section of the X-ray beam uniform are described. Methods of obtaining the desired X-ray-beam field size, optimum frequency spectrum and elminating the neutron flux are all described. A method of obtaining a plurality of station operation is also described which makes the process more efficient and economical. The satisfying of these issues makes transition radiation an exellent moderate-priced X-ray source for lithography.

  12. Spectra of Nearby Galaxies Measured with a New Very Broadband Receiver

    CERN Document Server

    Narayanan, Gopal; Erickson, Neal R; Chung, Aeree; Heyer, Mark H; Yun, Min; Irvine, William M; 10.1017/S1743921308021698

    2008-01-01

    Three-millimeter-wavelength spectra of a number of nearby galaxies have been obtained at the Five College Radio Astronomy Observatory (FCRAO) using a new, very broadband receiver. This instrument, which we call the Redshift Search Receiver, has an instantaneous bandwidth of 36 GHz and operates from 74 to 110.5 GHz. The receiver has been built at UMass/FCRAO to be part of the initial instrumentation for the Large Millimeter Telescope (LMT) and is intended primarily for determination of the redshift of distant, dust-obscured galaxies. It is being tested on the FCRAO 14m by measuring the 3mm spectra of a number of nearby galaxies. There are interesting differences in the chemistry of these galaxies.

  13. Full quantitative multiple-scattering analysis of X-ray absorption spectra: application to potassium hexacyanoferrat(II) and -(III) complexes.

    Science.gov (United States)

    Hayakawa, Kuniko; Hatada, Keisuke; D'Angelo, Paola; Della Longa, Stefano; Natoli, Calogero R; Benfatto, Maurizio

    2004-12-01

    A recently developed method to the full quantitative analysis of the XAS spectra extending from the absorption edge to the high-energy region is presented. This method is based on the use of two independent approaches to the analysis of the EXAFS and XANES data, the well-known GNXAS and the newly developed MXAN procedures. Herein, we report the application of this technique to two iron complexes of known structure where multiple-scattering effects are prominent, the potassium hexacyanoferrat(II) and -(III) crystals and aqueous solutions. The structural parameters obtained from refinements using the two methods are equal and compare quite well with crystallographic values. Small discrepancies between the experimental and calculated XANES spectra have been observed, and their origin has been investigated in the framework of non-muffin-tin correction. The ligand dependence of the theoretical spectra has been also examined. Analysis of the whole energy range of the XAS spectra has been found to be useful in elucidating both the type of ligands and the geometry of iron sites. These results are of particular use in studying the geometrical environment of metallic sites in proteins and complexes of chemical interest.

  14. Phosphorus K β X-Ray Emission Spectra and Valence-Band Structures of Transition-Metal Phosphides and GaAs 1-xPx

    Science.gov (United States)

    Sugiura, Chikara

    1996-07-01

    The P Kβ emission spectra in fluorescence from ZrP, NbP, MoP,HfP, TaP, WP, AgP2, CdP2, Mn3P2, Cd3P2 and GaAs1-xPxfor 0.2 ≤ x ≤ 1 are measured with a high-resolutiontwo-crystal vacuum spectrometer equipped with Ge(111) crystals. Theinfluence of metal atoms appears distinctly in the P Kβemission spectra of transition-metal phosphides. The effect ofarsenic atoms appears slightly in the P Kβ emission spectraof GaAs1-xPx. The P Kβ emission spectra of AgP2,CdP2, Cd3P2 and GaAs0.6 P0.4 are compared withavailable P L2,3 emission and XPS valence-band spectra ona common energy scale. It is shown that the P 3p electronsinteract fairly with the metal d electrons in the upper partof the valence band for MP ( M = Zr, Nb, Mo, Hf, Ta, W) and Mn3P2;considerable p-d, s mixing occurs in the middle part for AgP2and in the lower part for CdP2 and Cd3P2; and the Ga 3dstates mix fairly with the P 3s states in GaAs0.6P0.4.

  15. CMOS APS detector characterization for quantitative X-ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Endrizzi, Marco, E-mail: m.endrizzi@ucl.ac.uk [Dipartimento di Fisica, Università di Siena, Via Roma 56, 53100 Siena (Italy); Istituto Nazionale di Fisica Nucleare INFN, sezione di Pisa, 56127 Pisa (Italy); Oliva, Piernicola [Dipartimento di Chimica e Farmacia, Università di Sassari, via Piandanna 4, 07100 Sassari (Italy); Istituto Nazionale di Fisica Nucleare INFN, Sezione di Cagliari, 09042 Cagliari (Italy); Golosio, Bruno [Sezione di Matematica, Fisica e Ingegneria dell' Informazione, Università di Sassari, via Piandanna 4, 07100 Sassari (Italy); Istituto Nazionale di Fisica Nucleare INFN, Sezione di Cagliari, 09042 Cagliari (Italy); Delogu, Pasquale [Dipartimento di Fisica “E. Fermi”, Università di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Istituto Nazionale di Fisica Nucleare INFN, sezione di Pisa, 56127 Pisa (Italy)

    2013-03-01

    An X-ray Imaging detector based on CMOS Active Pixel Sensor and structured scintillator is characterized for quantitative X-ray imaging in the energy range 11–30 keV. Linearity, dark noise, spatial resolution and flat-field correction are the characteristics of the detector subject of investigation. The detector response, in terms of mean Analog-to-Digital Unit and noise, is modeled as a function of the energy and intensity of the X-rays. The model is directly tested using monochromatic X-ray beams and it is also indirectly validated by means of polychromatic X-ray-tube spectra. Such a characterization is suitable for quantitative X-ray imaging and the model can be used in simulation studies that take into account the actual performance of the detector.

  16. Interpretation of spectral paradox of cosmic X-ray background

    Institute of Scientific and Technical Information of China (English)

    李志青; 周又元

    1997-01-01

    The integrated spectrum of discrete X-ray sources (mainly the active galactic nuclei, AGN) is inconsistent with the observed spectrum of cosmic X-ray background (CXB), and it is so called CXB spectral paradox. The medium X-ray spectra of 68 AGNs are adopted, the evolution function of X-ray spectral indices is analyzed statistically, the fraction of CXB is calculated due to AGNs X-ray emission, which shows that almost 100% CXB comes from AGNs X-ray emission. Especially, the integrated spectrum in 2-10 keV is consistent with the observed spectrum of CXB. The spectral paradox of CXB can be interpreted by this result.

  17. X-ray emission from single Wolf-Rayet stars

    CERN Document Server

    Oskinova, Lidia

    2016-01-01

    This review briefly summarizes our knowledge of the X-ray emission from single WN, WC, and WO stars. These stars have relatively modest X-ray luminosities, typically not exceeding L_sun. The analysis of X-ray spectra usually reveals thermal plasma with temperatures reaching a few 10 MK. X-ray variability is detected in some WN stars. At present we don't fully understand how X-ray radiation in produced in WR stars, albeit there are some promising research avenues, such as the presence of CIRs in the winds of some stars. To fully understand WR stars we need to unravel mechanisms of X-ray production in their winds.

  18. Tomographic x-ray absorption spectroscopy.

    Energy Technology Data Exchange (ETDEWEB)

    Schroer, C. G.; Kuhlmann, M.; Gunzler, T. F.; Lengeler, B.; Richwin, M.; Griesebock, B.; Lutzenkirchen-Hecht, D.; Frahm, R.; Ziegler, E.; Mashayekhi, A.; Haeffner, D. R.; Grunwaldt, J. -D.; Baiker, A.; Experimental Facilities Division (APS); Aachen Univ.; HASYLAB at DESY; Bergische Univ. Wuppertal; ESRF; Inst. for Chemical and Bioengineering

    2004-01-01

    Hard x-ray absorption spectroscopy is combined with scanning microtomography to reconstruct full near edge spectra of an elemental species at each point on an arbitrary virtual section through a sample. These spectra reveal the local concentration of different chemical compounds of the absorbing element inside the sample and give insight into the oxidation state and the local projected free density of states. The method is implemented by combining a quick scanning monochromator and data acquisition system with a scanning microprobe setup based on refractive x-ray lenses. The full XANES spectra reconstructed at each point of the tomographic slice allow one to detect slight variations in concentration of the chemical compounds, such as Cu and Cu(I){sub 2}O.

  19. X-ray Properties of an Unbiased Hard X-ray Detected Sample of AGN

    Science.gov (United States)

    Winter, Lisa M.; Mushotzky, Richard F.; Tueller, Jack; Markwardt, Craig

    2007-01-01

    The SWIFT gamma ray observatory's Burst Alert Telescope (BAT) has detected a sample of active galactic nuclei (AGN) based solely on their hard X-ray flux (14-195keV). In this paper, we present for the first time XMM-Newton X-ray spectra for 22 BAT AGXs with no previously analyzed X-ray spectra. If our sources are a representative sample of the BAT AGN, as we claim, our results present for the first time global X-ray properties of an unbiased towards absorption (n(sub H) = 0.03), AGN sample. We find 9/22 low absorption (n(sub H) 2.0 keV. Five of the complex sources (NGC 612, ESO 362-G018, MRK 417, ESO 506-G027, and NGC 6860) are classified as Compton-thick candidates. Further, we find four more sources (SWIFT J0641.3+3257, SWIFT J0911.2+4533, SWIFT J1200.8+0650, and NGC 4992) with properties consistent with the hidden/buried AGN reported by Ueda et al. (2007). Finally, we include a comparison of the XMM EPIC spectra with available SWIFT X-ray Telescope (XRT) observations. From these comparisons, we find 6/16 sources with varying column densities, 6/16 sources with varying power law indices, and 13/16 sources with varying fluxes, over periods of hours to months. Flux and power law index are correlated for objects where both parameters vary.

  20. Diagram X-ray emission spectra of a hollow atom: the Kh alpha1,2 and Kh beta1,3 hypersatellites of Fe.

    Science.gov (United States)

    Diamant, R; Huotari, S; Hämäläinen, K; Sharon, R; Kao, C C; Deutsch, M

    2003-11-07

    High-resolution Fe K(h) beta(1,3) and K(h) alpha(1,2) hypersatellite spectra were measured, using monochromatized synchrotron radiation photoexcitation. The lines' energies, splitting, excitation thresholds, and the K(h) alpha(1)/K(h) alpha(2) intensity ratio were derived with high accuracy. Having both spectra, not hitherto available for any atom with high resolution, allows separating out the energy shifts of the outer levels caused by a K shell spectator vacancy. Comparison with ab initio relativistic multiconfigurational Dirac-Fock calculations reveals that while the influence of relativity and QED effects is mostly accounted for, discrepancies remain in the lines' intensity ratio, which sensitively measures the intermediacy of the coupling. Similar discrepancies, of unknown origin, are found in the energy shifts of the outer levels due to the final-state K shell spectator vacancy.

  1. Effects of tertiary MLC configuration on secondary neutron spectra from 18 MV x-ray beams for the Varian 21EX linear accelerator.

    Science.gov (United States)

    Howell, Rebecca M; Kry, Stephen F; Burgett, Eric; Followill, David; Hertel, Nolan E

    2009-09-01

    The effect of the jaw configuration and the presence and configuration of the tertiary multileaf collimator (MLC) on the secondary neutron spectra for an 18 MV Varian 21EX linear accelerator (linac) is investigated in detail. The authors report the measured spectra for four collimator (jaw-and-MLC) configurations. These configurations represent the extreme settings of the jaws and MLC and should therefore describe the range of possible fluence and spectra that may be encountered during use of this linac. In addition to measurements, a Monte Carlo model was used to simulate the four collimator configurations and calculate the energy spectra and fluence at the same location as it was measured. The Monte Carlo model was also used to calculate the sources of neutron production in the linac head for each collimator configuration. They found that photoneutron production in the linac treatment head is dominated by the order in which the primary photon beam intercepts the high-Z material. The primary collimator, which has the highest position in the linac head (in a fixed location), is the largest source of secondary neutrons. Thereafter, the collimator configuration plays a role in where the neutrons originate. For instance, if the jaws are closed, they intercept the beam and contribute substantially to the secondary neutron production. Conversely, if the jaws are open, the MLC plays a larger role in neutron production (assuming, of course, that it intercepts the beam). They found that different collimator configurations make up to a factor of 2 difference in the ambient dose equivalent.

  2. A hard X-ray study of the ultraluminous X-ray source NGC 5204 X-1 with NuSTAR and XMM-Newton

    DEFF Research Database (Denmark)

    Mukherjee, E. S.; Walton, D. J.; Bachetti, M.;

    2015-01-01

    We present the results from coordinated X-ray observations of the ultraluminous X-ray source NGC 5204 X-1 performed by the Nuclear Spectroscopic Telescope Array and XMM-Newton in early 2013. These observations provide the first detection of NGC 5204 X-1 above 10 keV, extending the broadband...

  3. Measurement of wavelengths and lamb shifts for inner-shell transitions in Fe XVIII-XXIV. [from solar flare X-ray spectra

    Science.gov (United States)

    Seely, J. F.; Feldman, U.; Safronova, U. I.

    1986-01-01

    The wavelengths of inner-shell 1s-2p transitions in the ions Fe XVIII-XXIV have been measured in solar flare spectra recorded by the Naval Research Laboratory crystal spectrometer (SOLFLEX) on the Air Force P78-1 spacecraft. The measurements are compared with previous measurements and with recently calculated wavelengths. It is found that the measured wavelengths are systematically larger than the wavelengths calculated using the Z-expansion method by up to 0.65 mA. For the more highly charged ions, these differences can be attributed to the QED contributions to the transition energies that are not included in the Z-expansion calculations.

  4. The X-ray Spectral Evolution of Galactic Black Hole X-ray Binaries Toward Quiescence

    CERN Document Server

    Plotkin, Richard M; Jonker, Peter G

    2013-01-01

    Most transient black hole X-ray binaries (BHXBs) spend the bulk of their time in a quiescent state, where they accrete matter from their companion star at highly sub-Eddington luminosities (we define quiescence here as a normalized Eddington ratio l_x = L_{0.5-10 keV}}/L_{Edd} < 1e-5). Here, we present Chandra X-ray imaging spectroscopy for three BHXB systems (H 1743-322, MAXI J1659-152, and XTE J1752-223) as they fade into quiescence following an outburst. Multiple X-ray observations were taken within one month of each other, allowing us to track each individual system's X-ray spectral evolution during its decay. We compare these three systems to other BHXB systems. We confirm that quiescent BHXBs have softer X-ray spectra than low-hard state BHXBs, and that quiescent BHXB spectral properties show no dependence on the binary system's orbital parameters. However, the observed anti-correlation between X-ray photon index and l_x in the low-hard state does not continue once a BHXB enters quiescence. Instead, ...

  5. Can a Dusty Warm Absorber Model Reproduce the Soft X-ray Spectra of MCG-6-30-15 and Mrk 766?

    CERN Document Server

    Sako, M; Branduardi-Raymont, G; Kaastra, J S; Brinkman, A C; Page, M J; Behar, E; Paerels, F B S; Kinkhabwala, A; Liedahl, D A; Den Herder, J W A

    2003-01-01

    XMM-Newton RGS spectra of MCG-6-30-15 and Mrk 766 exhibit complex discrete structure, which was interpreted in a paper by Branduardi-Raymont et al. (2001) as evidence for the existence of relativistically broadened Lyman alpha emission from carbon, nitrogen, and oxygen, produced in the inner-most regions of an accretion disk around a Kerr black hole. This suggestion was subsequently criticized in a paper by Lee et al. (2001), who argued that for MCG-6-30-15, the Chandra HETG spectrum, which is partially overlapping the RGS in spectral coverage, is adequately fit by a dusty warm absorber model, with no relativistic line emission. We present a reanalysis of the original RGS data sets in terms of the Lee et al. (2001) model, and demonstrate that spectral models consisting of a smooth continuum with ionized and dust absorption alone cannot reproduce the RGS spectra of both objects. The original relativistic line model with warm absorption proposed by Branduardi-Raymont et al. (2001) provides a superior fit to the...

  6. Valence-to-core-detected X-ray absorption spectroscopy

    DEFF Research Database (Denmark)

    Hall, Eleanor R.; Pollock, Christopher J.; Bendix, Jesper

    2014-01-01

    X-ray absorption spectroscopy (XAS) can provide detailed insight into the electronic and geometric structures of transition-metal active sites in metalloproteins and chemical catalysts. However, standard XAS spectra inherently represent an average contribution from the entire coordination...

  7. Simultaneous optical/X-ray study of GS 1354-64 (=BW Cir) during hard outburst: evidence for optical cyclo-synchrotron emission from the hot accretion flow

    Science.gov (United States)

    Pahari, Mayukh; Gandhi, Poshak; Charles, Philip A.; Kotze, Marissa M.; Altamirano, Diego; Misra, Ranjeev

    2017-07-01

    We present results from simultaneous optical [South African Large Telescope (SALT)] and X-ray (Swift and INTEGRAL) observations of GS 1354-64/BW Cir during the 2015 hard state outburst. During the rising phase, optical/X-ray time series shows a strong anti-correlation with X-ray photons lagging optical. Optical and X-ray power spectra show quasi-periodic oscillations (QPOs) at a frequency of ˜18 mHz with a confidence level of at least 99 per cent. Simultaneous fitting of Swift/XRT and INTEGRAL spectra in the range 0.5-1000.0 keV shows non-thermal, power-law-dominated (>90 per cent) spectra with a hard power-law index of 1.48 ± 0.03, inner disc temperature of 0.12 ± 0.01 keV and an inner disc radius of ˜3000 km. All evidence is consistent with cyclo-synchrotron radiation in a non-thermal, hot electron cloud extending to ˜100 Schwarzschild radii being a major physical process for the origin of optical photons. At outburst peak about one month later, when the X-ray flux rises and the optical drops, the apparent features in the optical/X-ray correlation vanish and the optical auto correlation widens. Although ˜0.19 Hz QPO is observed from the X-ray power spectra, the optical variability is dominated by the broad-band noise, and the inner disc temperature increases. These results support a change in the dominant optical emission source between outburst rise and peak, consistent with a weakening of hot flow as the disc moves in.

  8. Topological X-Rays Revisited

    Science.gov (United States)

    Lynch, Mark

    2012-01-01

    We continue our study of topological X-rays begun in Lynch ["Topological X-rays and MRI's," iJMEST 33(3) (2002), pp. 389-392]. We modify our definition of a topological magnetic resonance imaging and give an affirmative answer to the question posed there: Can we identify a closed set in a box by defining X-rays to probe the interior and without…

  9. X-ray instrumentation for SR beamlines

    CERN Document Server

    Kovalchuk, M V; Zheludeva, S I; Aleshko-Ozhevsky, O P; Arutynyan, E H; Kheiker, D M; Kreines, A Y; Lider, V V; Pashaev, E M; Shilina, N Y; Shishkov, V A

    2000-01-01

    The main possibilities and parameters of experimental X-ray stations are presented: 'Protein crystallography', 'X-ray structure analysis', 'High-precision X-ray optics', 'X-ray crystallography and material science', 'X-ray topography', 'Photoelectron X-ray standing wave' that are being installed at Kurchatov SR source by A.V. Shubnikov Institute of Crystallography.

  10. X-ray Fluorescence Sectioning

    CERN Document Server

    Cong, Wenxiang

    2012-01-01

    In this paper, we propose an x-ray fluorescence imaging system for elemental analysis. The key idea is what we call "x-ray fluorescence sectioning". Specifically, a slit collimator in front of an x-ray tube is used to shape x-rays into a fan-beam to illuminate a planar section of an object. Then, relevant elements such as gold nanoparticles on the fan-beam plane are excited to generate x-ray fluorescence signals. One or more 2D spectral detectors are placed to face the fan-beam plane and directly measure x-ray fluorescence data. Detector elements are so collimated that each element only sees a unique area element on the fan-beam plane and records the x-ray fluorescence signal accordingly. The measured 2D x-ray fluorescence data can be refined in reference to the attenuation characteristics of the object and the divergence of the beam for accurate elemental mapping. This x-ray fluorescence sectioning system promises fast fluorescence tomographic imaging without a complex inverse procedure. The design can be ad...

  11. Soft X-ray optics

    CERN Document Server

    Spiller, Eberhard A

    1993-01-01

    This text describes optics mainly in the 10 to 500 angstrom wavelength region. These wavelengths are 50 to 100 times shorter than those for visible light and 50 to 100 times longer than the wavelengths of medical x rays or x-ray diffraction from natural crystals. There have been substantial advances during the last 20 years, which one can see as an extension of optical technology to shorter wavelengths or as an extension of x-ray diffraction to longer wavelengths. Artificial diffracting structures like zone plates and multilayer mirrors are replacing the natural crystals of x-ray diffraction.

  12. Luminescence properties after X-ray irradiation for dosimetry

    Science.gov (United States)

    Hong, Duk-Geun; Kim, Myung-Jin

    2016-05-01

    To investigate the luminescence characteristics after exposure to X-ray radiation, we developed an independent, small X-ray irradiation system comprising a Varian VF-50J mini X-ray generator, a Pb collimator, a delay shutter, and an Al absorber. With this system, the apparent dose rate increased linearly to 0.8 Gy/s against the emission current for a 50 kV anode potential when the shutter was delayed for an initial 4 s and the Al absorber was 300 µm thick. In addition, an approximately 20 mm diameter sample area was irradiated homogeneously with X rays. Based on three-dimensional (3D) thermoluminescence (TL) spectra, the small X-ray irradiator was considered comparable to the conventional 90Sr/90Y beta source even though the TL intensity from beta irradiation was higher than that from X-ray irradiation. The single aliquot regenerative (SAR) growth curve for the small X-ray irradiator was identical to that for the beta source. Therefore, we concluded that the characteristics of the small X-ray irradiator and the conventional 90Sr/90Y beta source were similar and that X ray irradiation had the potential for being suitable for use in luminescence dosimetry.

  13. X射线连续谱法诊断铝丝阵Z箍缩等离子体温度%X-ray continuum spectra for diagnosing plasma temperature in aluminum wire array Z-pinches

    Institute of Scientific and Technical Information of China (English)

    蒙世坚; 李正宏; 秦义; 叶繁; 徐荣昆

    2011-01-01

    Time-integrated X-ray continuum spectra measured with spherical bent quartz crystal and CCD in aluminum wire array Z-pinches, provide electron temperature by fitting the continuum slope.More data obtained for fitting and markedly reduced influence of line radiation by removing the data superimposed with line spectra, make the temperature in hot core region of plasma more reliable.In experiment of shot No.09076, the core temperature is around 250 eV, ranging from 241 eV to 258 eV at a 95% confidence level.%用球面石英弯晶衍射、CCD记录测量铝丝阵Z箍缩中的时间积分X射线连续能谱,并由连续谱斜率拟合出电子温度.该法获得的拟合数据点多,能有效筛除含线辐射的数据,减弱线辐射的影响,求得更可靠的等离子体核心高温区的温度.以发次09076为例,核心温度约为250 eV,在95%的置信度范围里,其变化范围约241-258 eV.

  14. A strong NH…Br vibrational behaviour studied through X-ray, vibrational spectra and quantum chemical studies in an isomorphous crystal: 2-Nitroanilinium bromide.

    Science.gov (United States)

    Anitha, R; Athimoolam, S; Gunasekaran, M

    2015-03-05

    A needle shaped transparent light brown crystals of 2-nitroanilinium bromide were successfully synthesized and crystallized from an aqueous mixture by slow evaporation technique. Single crystal XRD studies confirm the crystalline phase of this isomorphous compound which contains a positively charge 2-nitroanilinium cation and a negatively charged bromide anion. The solid phase FT-IR and FT-Raman spectra of the compound have been recorded in the range of 4000-400cm(-1). The observed modes are correlated by the factor group theory analysis and different IR and Raman active species were identified. Geometrical optimisations were carried out and harmonic vibrational wave numbers were computed for the minimum energy molecular structure at RHF level invoking 6-311++G(d,p) and SDD basis sets. Optimised molecular geometry was compared with the crystallographic data. The calculated wavenumbers were compared with the experimental values. The NH vibrational bands are shifted from its normal range and the shifting is associated with the influence of the intermolecular hydrogen bonds in the crystal. A strong intensity peak in theoretical and corresponding band in experimental confirms the presence of NH…Br interaction as predicted in crystalline state.

  15. Characterization of new hard X-ray Cataclysmic Variables

    CERN Document Server

    Bernardini, F; Falanga, M; Mukai, K; Matt, G; Bonnet-Bidaud, J -M; Masetti, N; Mouchet, M

    2012-01-01

    We aim at characterizing a sample of 9 new hard X-ray selected Cataclysmic Variable (CVs), to unambiguously identify them as magnetic systems of the Intermediate Polar (IP) type. We performed timing and spectral analysis by using X-ray, and simultaneous UV and optical data collected by XMM-Newton, complemented with hard X-ray data provided by INTEGRAL and Swift. The pulse arrival time were used to estimate the orbital periods. The X-ray spectra were fitted using composite models consisting of different absorbing columns and emission components. Strong X-ray pulses at the White Dwarf (WD) spin period are detected and found to decrease with energy. Most sources are spin-dominated systems in the X-rays, though four are beat dominated at optical wavelengths. We estimated the orbital period in all system (except for IGR J16500-3307), providing the first estimate for IGR J08390-4833, IGR J18308-1232, and IGR J18173-2509. All X-ray spectra are multi-temperature. V2069 Cyg and RX J0636+3535 posses a soft X-ray optica...

  16. The broadband microwave spectra of the monoterpenoids thymol and carvacrol: Conformational landscape and internal dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, D.; Shubert, V. A. [Max Planck Institute for the Structure and Dynamics of Matter, Hamburg (Germany); The Center for Free-Electron Laser Science, Hamburg (Germany); Giuliano, B. M. [Center for Astrobiology, INTA-CSIC, Torrejón de Ardoz, Madrid (Spain); Schnell, M., E-mail: melanie.schnell@mpsd.mpg.de [Max Planck Institute for the Structure and Dynamics of Matter, Hamburg (Germany); The Center for Free-Electron Laser Science, Hamburg (Germany); The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Hamburg (Germany)

    2014-07-21

    The rotational spectra of the monoterpenoids thymol and carvacrol are reported in the frequency range 2–8.5 GHz, obtained with broadband Fourier-transform microwave spectroscopy. For carvacrol four different conformations were identified in the cold conditions of the molecular jet, whereas only three conformations were observed for thymol. The rotational constants and other molecular parameters are reported and compared with quantum chemical calculations. For both molecules, line splittings due to methyl group internal rotation were observed and the resulting barrier heights could be determined. The experimental barrier heights, 4.0863(25) kJ/mol for trans-carvacrol-A, 4.4024(16) kJ/mol for trans-carvacrol-B, and 0.3699(11) kJ/mol for trans-thymol-A, are compared with similar molecules.

  17. Revealing a hard X-ray spectral component reverberating within one light hour of the central Supermassive Black Hole in Ark 564

    CERN Document Server

    Giustini, M; Reeves, J N; Miller, L; Legg, E; Kraemer, S B; George, I M

    2015-01-01

    Ark 564 (z=0.0247) is an X-ray bright NLS1. By using advanced X-ray timing techniques, Legg et al. (2012) discovered an excess of "delayed" emission in the hard X-ray band (4-7.5 keV) following about 1000 seconds after "flaring" light in the soft X-ray band (0.4-1 keV). We report on the X-ray spectral analysis of eight XMM-Newton and one Suzaku observation of Ark 564. High-resolution spectroscopy was performed with the RGS in the soft X-ray band, while broad-band spectroscopy was performed with the EPIC-pn and XIS/PIN instruments. We analysed time-averaged, flux-selected, and time-resolved spectra. Despite the large variability in flux, the broad band spectral shape of Ark 564 is not dramatically varying and can be reproduced either by a superposition of a power law and a blackbody emission, or by a Comptonized power law emission model. High resolution spectroscopy revealed the presence of ionised gas along the line of sight at the systemic redshift of the source, with a low column density and a range of ioni...

  18. Two methods for studying the X-ray variability

    Science.gov (United States)

    Yan, Shu-Ping; Ji, Li; Méndez, Mariano; Wang, Na; Liu, Siming; Li, Xiang-Dong

    2016-04-01

    The X-ray aperiodic variability and quasi-periodic oscillation (QPO) are the important tools to study the structure of the accretion flow of X-ray binaries. However, the origin of the complex X-ray variability from X-ray binaries remains yet unsolved. We proposed two methods for studying the X-ray variability. One is amplitude-ratio spectrum analysis method. The other is mapping analysis method. Based on the consideration that the aperiodic variability originates from all spectral components whereas the QPO originates from one spectral component, we divided the root-mean-square (rms) amplitude spectrum of the power density spectrum (PDS) broadband noise component by the amplitude spectrum of an accompanying QPO, and first identified a high-frequency (> 10 Hz) aperiodic variability from the accretion disk (Yan et al. 2013). We now present the evolution of the amplitude-ratio spectrum with the cycle phase of the heartbeat state of the microquasar GRS 1915+105. We produced the energy-frequency-power map to investigate the origin of the X-ray variability, and show that most aperiodic X-ray variability is produced in the corona, and the low-frequency aperiodic variability from the corona is significant in the hard phase of the cycle phase of the heartbeat state of GRS 1915+105 while the low-frequency aperiodic variability from the disk and the corona are both significant in the soft phase.

  19. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... clothing that might interfere with the x-ray images. Women should always inform their physician and x-ray ... small burst of radiation that passes through the body, recording an image on photographic film or a special detector. Different ...

  20. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... bone absorbs much of the radiation while soft tissue, such as muscle, fat and organs, allow more of the x-rays to pass through them. As a result, bones appear white on the x-ray, soft tissue shows up in shades of gray and air ...