WorldWideScience

Sample records for broadband x-ray spectrum

  1. 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.

  2. 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...

  3. 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.

  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. Broad-band hard X-ray reflectors

    DEFF Research Database (Denmark)

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

    1997-01-01

    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 of ...

  6. The Broad-band X-ray Spectrum of IC 4329A from a Joint NuSTAR/Suzaku Observation

    CERN Document Server

    Brenneman, Laura; Fuerst, F; Matt, G; Elvis, M; Harrison, F A; Ballantyne, D R; Boggs, S E; Christensen, F E; Craig, W W; Fabian, A C; Grefenstette, B W; Hailey, C J; Madsen, K K; Marinucci, A; Rivers, E; Stern, D; Walton, D J; Zhang, W W

    2014-01-01

    We have obtained a deep, simultaneous observation of the bright, nearby Seyfert galaxy IC 4329A with Suzaku and NuSTAR. Through a detailed spectral analysis, we are able to robustly separate the continuum, absorption and distant reflection components in the spectrum. The absorbing column is found to be modest at $N_H = 6 \\times 10^{21}$ cm$^2$, and does not introduce any significant curvature in the Fe K band. We are able to place a strong constraint on the presence of a broadened Fe K{\\alpha} line: $E = 6.46^{+0.08}_{-0.07}$ keV rest frame with ${\\sigma} = 0.33^{+0.08}_{-0.07}$ keV and $EW = 34^{+8}_{-7}$ eV, though we are not able to constrain any of the parameters of a relativistic reflection model. These results highlight the range in broad Fe K{\\alpha} line strengths observed in nearby, bright AGN (roughly an order of magnitude), and imply a corresponding range in the physical properties of the inner accretion disk in these sources. We have also updated our previously reported measurement of the high-ene...

  7. 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...

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

    Science.gov (United States)

    Papadakis, I. E.; Nicastro, F.; Panagiotou, C.

    2016-06-01

    Context. We present the results from a detailed analysis of the 2007 Swift monitoring campaign of the quasar PG1211+143. Aims: We study its broad-band optical/UV-X-ray spectral energy distribution and its variations, with the use of physically motivated models. Methods: We constructed broad-band, optical/UV-X-ray spectral energy distributions over three X-ray flux intervals, and we fitted them with a model which accounts for the disc and the X-ray coronal emission. We also added a spectral model component to account for the presence of the warm absorber which has been well established from past observations of the source. Results: We detected no optical/UV variations over the two-month period of the monitoring campaign. On the other hand, the X-rays are highly variable in a correlated way in the soft and hard X-ray bands with an amplitude larger than has been commonly observed in nearby Seyferts, even on longer time scales. 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 in slope and normalization. The absorber covers almost 90% of the central source. It is outflowing with a velocity less than 2.3 × 104 km s-1 (3σ upper limit), and has a column density of log NH ~ 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, ΔR/R, is less than 0.1. The absorber's ionization parameter variations can explain the larger than average amplitude of the X-ray variations. Conclusions: The absence of optical/UV variations are consistent with the high black hole mass estimate of ~108M⊙ for this object, which implies variability time scales longer than the period of the Swift observations. It argues against the presence of inward propagating fluctuations in the disc as the reason for the flux variability in this

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

    OpenAIRE

    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 lat...

  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. Broadband high-resolution x-ray frequency combs

    CERN Document Server

    Cavaletto, Stefano M; Ott, Christian; Buth, Christian; Pfeifer, Thomas; Keitel, Christoph H

    2014-01-01

    Optical frequency combs have had a remarkable impact on precision spectroscopy. Enabling this technology in the x-ray domain is expected to result in wide-ranging applications, such as stringent tests of astrophysical models and quantum electrodynamics, a more sensitive search for the variability of fundamental constants, and precision studies of nuclear structure. Ultraprecise x-ray atomic clocks may also be envisaged. In this work, an x-ray pulse-shaping method is put forward to generate a comb in the absorption spectrum of an ultrashort high-frequency pulse. The method employs an optical-frequency-comb laser, manipulating the system's dipole response to imprint a comb on an excited transition with a high photon energy. The described scheme provides higher comb frequencies and requires lower optical-comb peak intensities than currently explored methods, preserves the overall width of the optical comb, and may be implemented by presently available x-ray technology.

  12. Broadband high-resolution X-ray frequency combs

    Science.gov (United States)

    Cavaletto, Stefano M.; Harman, Zoltán; Ott, Christian; Buth, Christian; Pfeifer, Thomas; Keitel, Christoph H.

    2014-07-01

    Optical frequency combs have had a remarkable impact on precision spectroscopy. Enabling this technology in the X-ray domain is expected to result in wide-ranging applications, such as stringent tests of astrophysical models and quantum electrodynamics, a more sensitive search for the variability of fundamental constants, and precision studies of nuclear structure. Ultraprecise X-ray atomic clocks may also be envisaged. In this work, an X-ray pulse-shaping method is proposed to generate a comb in the absorption spectrum of an ultrashort high-frequency pulse. The method employs an optical-frequency-comb laser, manipulating the system's dipole response to imprint a comb on an excited transition with a high photon energy. The described scheme provides higher comb frequencies and requires lower optical-comb peak intensities than currently explored methods, preserves the overall width of the optical comb, and may be implemented using currently available X-ray technology.

  13. Uranium M x-ray emission spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Keski-Rahkonen, O.; Krause, M.O.

    1977-03-01

    The uranium M x-ray spectrum from a thick metallic target excited by 12-keV electrons was measured by the PAX (photoelectron spectrometry for the analysis of x rays) technique. Energies of the strongest lines were obtained with an accuracy of 0.1 eV using Ag L..beta../sub 1/ and Ag L..cap alpha../sub 1/ as standards. Widths of the uranium lines were obtained by deconvoluting the measured Voigt profiles, and the experimental values were found to agree satisfactorily with McGuire's Hartree-Slater predictions. Natural widths of 4.0(3) and 3.8(3) eV were derived for the M/sub 4/ and M/sub 5/ levels, respectively, and the energies of the M/sub 4/, M/sub 5/, N/sub 2/, and N/sub 3/ levels in uranium metal were determined. Relative intensities of the M lines were measured, and branching ratios were found to be in fair agreement with relativistic Hartree-Slater predictions. The satellite structures of the M..cap alpha../sub 1/ and M..beta.. lines were interpreted in terms of the pertinent multiple-hole configurations. Finally, an approximate analytic expression for the Voigt half-width and its graphical representation are given.

  14. 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.

  15. The hard X-ray view of Giga-Hertz Peaked Spectrum Radio Galaxies

    CERN Document Server

    Guainazzi, M; Stanghellini, C; Grandi, P; Piconcelli, E; Azibuke, C

    2005-01-01

    We present the first broadband X-ray observations of 4 Giga-Hertz Peaked Spectrum (GPS) radio galaxies at redshift 2 keV) X-rays. All sources were detected. Their radio-to-X-ray spectral energy distributions are similar, except for PKS0941-080, which is by about two orders of magnitude X-ray under-luminous. The comparison between the full sample of GPS galaxies with measurements in hard X-rays and a control sample of radio galaxies rules out intrinsic X-ray weakness as an origin for the lower detection rate of GPS sources in X-ray surveys. 4 out of 7 GPS galaxies exhibit large X-ray column densities, whereas for the remaining 3 this measurement is hampered by the poor spectral statistics. Bearing in mind the still low number statistics in both the GPS and the control sample, the average column density measured in GPS galaxies is larger than in FRI or Broad Line Region FRII radio galaxies, but consistent with that measured in High-Excitation FRII galaxies. This leads to locating the absorbing gas in an obscuri...

  16. A nuclear spectrum generator for semiconductor X-ray detectors

    International Nuclear Information System (INIS)

    A nuclear spectrum generator for semiconductor X-ray detectors is designed in this paper. It outputs step ramp signals with random distribution in amplitude and time according to specified reference spectrum. The signals are similar to the signals from an actual semiconductor X-ray detector, and can be use to check spectrum response characteristics of an X-ray fluorometer. This helps improving energy resolution of the X-ray fluorometer. The spectrum generator outputs step ramp signals satisfying the probability density distribution function of any given reference spectrum in amplitude through sampling on the basis of 32-bit randomizer. The system splits 1024 interval segmentation of the time that the step ramp signals appear, and calculates the appearance probability of step ramp signals in different intervals and the average time between the time intervals, by random sampling. The step ramp signals can meet the rule of exponential distribution in time. Test results of the spectrum generator show that the system noise is less than 2.43 mV, the output step ramp signals meet the Poisson distribution in counting rate and the probability density distribution function of the reference spectrum in amplitude. The counting rate of the output step ramp signals can be adjusted. It meets the rule of the output signals from semiconductor X-ray detectors, such as Si-pin detector and silicon drift detector. (authors)

  17. The X-ray Spectrum of Supernova Remnant 1987A

    CERN Document Server

    Michael, E; McCray, R; Hwang, U; Burrows, D N; Park, S; Garmire, G P; Holt, S S; Hasinger, G; Michael, Eli; Zhekov, Svetozar; Cray, Richard Mc; Hwang, Una; Burrows, David N.; Park, Sangwook; Garmire, Gordon P.; Holt, Stephen S.; Hasinger, Guenther

    2002-01-01

    We discuss the X-ray emission observed from Supernova Remnant 1987A with the Chandra X-ray Observatory. We analyze a high resolution spectrum obtained in 1999 October with the high energy transmission grating (HETG). From this spectrum we measure the strengths and an average profile of the observed X-ray lines. We also analyze a high signal-to-noise ratio CCD spectrum obtained in 2000 December. The good statistics (~ 9250 counts) of this spectrum and the high spatial resolution provided by the telescope allow us to perform spectroscopic analyses of different regions of the remnant. We discuss the relevant shock physics that can explain the observed X-ray emission. The X-ray spectra are well fit by plane parallel shock models with post-shock electron temperatures of ~ 2.6 keV and ionization ages of ~ 6 x 10^10 cm^3/s. The combined X-ray line profile has a FWHM of ~ 5000 km/s, indicating a blast wave speed of ~ 3500 km/s. At this speed, plasma with a mean post-shock temperature of ~ 17 keV is produced. This is ...

  18. 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...... 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 black body 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...

  19. Effects of X-rays spectrum on the dose

    International Nuclear Information System (INIS)

    The X-ray equipment for diagnosis comes in different sizes and shapes depending on the scan type to perform. The X-ray spectrum is the energy distribution of the beam photons and consists of a continuous spectrum of photons braking and discrete spectrum due to the characteristic photons. The knowledge of the X-rays spectrum is important to understand like they affect the voltage changes (k Vp), current (m A), time (s) and the type of filter in the interaction mechanisms between X-rays and patient's body, the image receptor or other material that gets in the beam. Across the spectrum can be estimated the absorbed dose in any point of the patient, the quality of the image and the scattered radiation (which is related to the dose received by the equipment operator). The Monte Carlo method was used by MCNP5 code to calculate the spectrum of X-rays that occurs when a monoenergetic electron beam of 250 keV interact with targets of Mo, Rh and W. The spectra were calculated with and without filter, and the values of ambient dose equivalent were estimated, as well as the air kerma. (Author)

  20. Broadband high-resolution x-ray frequency combs

    OpenAIRE

    Cavaletto, S.; Harman, Z.; Ott, C; Buth, C.; Pfeifer, T; Keitel, C.

    2014-01-01

    Optical frequency combs have had a remarkable impact on precision spectroscopy1, 2, 3. Enabling this technology in the X-ray domain is expected to result in wide-ranging applications, such as stringent tests of astrophysical models and quantum electrodynamics4, a more sensitive search for the variability of fundamental constants5, and precision studies of nuclear structure6. Ultraprecise X-ray atomic clocks may also be envisaged7. In this work, an X-ray pulse-shaping method is proposed to gen...

  1. The Swift BAT-detected Seyfert 1 Galaxies: X-ray Broadband Properties and Warm Absorbers

    CERN Document Server

    Winter, Lisa M; McKernan, Barry; Kallman, Tim

    2011-01-01

    We present results from an analysis of the broad-band, 0.3-195 keV, X-ray spectra of 48 Seyfert 1-1.5 sources detected in the very hard X-rays with the Swift Burst Alert Telescope (BAT). This sample is selected in an all-sky survey conducted in the 14-195 keV band. Therefore, our sources are largely unbiased towards both obscuration and host galaxy properties. Our detailed and uniform model fits to Suzaku/BAT and XMM-Newton/BAT spectra include the neutral absorption, direct power-law, reflected emission, soft excess, warm absorption, and narrow Fe K-alpha emission properties for the entire sample. We significantly detect O VII and O VIII edges in 52% of our sample. The strength of these detections are strongly correlated with the neutral column density measured in the spectrum. Among the strongest detections, X-ray grating and UV observations, where available, indicate outflowing material. The ionized column densities of sources with O VII and O VIII detections are clustered in a narrow range with N$_{\\rm war...

  2. 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.

  3. X-ray Measurements of Black Hole X-ray Binary Source GRS 1915+105 and the Evolution of Hard X-ray Spectrum

    Indian Academy of Sciences (India)

    R. K. Manchanda

    2000-06-01

    We report the spectral measurement of GRS 1915+105 in the hard X-ray energy band of 20-140keV. The observations were made on March 30th, 1997 during a quiescent phase of the source. We discuss the mechanism of emission of hard X-ray photons and the evolution of the spectrum by comparing the data with earlier measurements and an axiomatic model for the X-ray source.

  4. The hard x-ray spectrum of SN 1987A

    International Nuclear Information System (INIS)

    The authors report the discovery of hard x-rays in the energy range from 20 to 350 keV. The hard x-rays were first observed on August 10, 1987 and thereafter SN 1987A became the main target of the observatory. The measured spectrum is extremely hard. At high energies the photon spectrum has a power law index of ∼ 1.4. At lower energies the spectrum becomes flatter and there is indication of a cut-off below 25 keV. The luminosity in the above energy band is ∼ 2 x 1038 erg/s. The flux shows little variation between August 10 and beginning of October

  5. X-ray spectrum of a pinned charge density wave

    OpenAIRE

    Rosso, Alberto; Giamarchi, Thierry

    2004-01-01

    We calculate the x-ray diffraction spectrum produced by a pinned charge density wave (CDW). The signature of the presence of a CDW consists of two satellite peaks, asymmetric as a consequence of disorder. The shape and the intensity of these peaks are determined in the case of a collective weak pinning using the variational method. We predict divergent asymmetric peaks, revealing the presence of a Bragg glass phase. We deal also with the long range Coulomb interactions, concluding that both p...

  6. 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 \

  7. The CHANDRA X-ray Grating Spectrum of Eta Carinae

    CERN Document Server

    Corcoran, M F; Petre, R; Ishibashi, K; Davidson, K; Townsley, L K; Smith, R; White, S; Viotti, R; Damineli, A

    2001-01-01

    Eta Car may be the most massive and luminous star in the Galaxy and is suspected to be a massive, colliding wind binary system. The CHANDRA X-ray observatory has obtained a calibrated, high-resolution X-ray spectrum of the star uncontaminated by the nearby extended soft X-ray emisssion. Our 89 ksec CHANDRA observation with the High Energy Transmission Grating Spectrometer (HETGS) shows that the hot gas near the star is non-isothermal. The temperature distribution may represent the emission on either side of the colliding wind bow shock, effectively ``resolving'' the shock. The pre-shock wind velocities are ~500 and ~ 2000 km/s in our analysis, and these velocities are interpreted as the terminal velocities of the winds from Eta Car and from the hidden companion star. The abundances of Si and Fe are significantly non-solar based on the strengths of the observed H- and He-like emission lines. The iron fluorescent line at 1.93 Angstrom, first detected by ASCA, is clearly resolved from the thermal iron line in th...

  8. 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 ke...... 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....

  9. Space-Resolved Spectrum Diagnose by Soft X-Ray Transmission Grating Spectrometer

    Science.gov (United States)

    Shang, Wanli; Zhao, Yang; Xiong, Gang; Yang, Jiamin; Zhu, Tuo

    2011-02-01

    A space-resolving transmission grating spectrometer is established on the “Shenguang-III" prototype laser facility and an iterative procedure for unfolding the X-ray spectrum with spatial resolution is described. The diagnostics is applied to measure the X-ray spectrum from laser-entered gold target and the typical space-resolved spectrum is provided. The relative standard uncertainty of the X-ray spectrum from the laser-generated plasma is also determined.

  10. A new interpretation of the remarkable X-ray spectrum of the symbiotic star CH Cyg

    OpenAIRE

    Wheatley, Peter J.; Kallman, Timothy R.

    2006-01-01

    We have reanalysed the ASCA X-ray spectrum of the bright symbiotic star CH Cyg, which exhibits apparently distinct hard and soft X-ray components. Our analysis demonstrates that the soft X-ray emission can be interpreted as scattering of the hard X-ray component in a photo-ionised medium surrounding the white dwarf. This is in contrast to previous analyses in which the soft X-ray emission was fitted separately and assumed to arise independently of the hard X-ray component. We note the strikin...

  11. Characterization of a triboelectric x-ray spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Moya-Sanchez, E. Ulises; Romo-Espejel, J. A.; Aceves-Aldrete, F. J. [Departamento de Fisica, CUCEI, Universidad de Guadalajara (Mexico)

    2012-10-23

    Low-energy X-ray imaging system has been useful in medical diagnostic in order to obtain high contrast in soft tissue. Recently, Camara et al. and most recently Hird et al. have produced low-energy X-rays using a triboelectric effect. The main aim of this work is to characterize the penetration (beam quality) of a triboelectric X-ray source in terms of the computed Half Value Layer (HVL). Additionally, the computed HVL of the triboelectric X-ray source has been compared with the HVL of X-ray tube Mo-anode (Apogee 5000). According to our computations the triboelectric X-ray source has a similar penetration such as a X-ray tube source.

  12. Broad band X-ray spectrum of KS 1947+300 with BeppoSAX

    CERN Document Server

    Naik, S; Dotani, T; Paul, B

    2006-01-01

    We present results obtained from three BeppoSAX observations of the accretion-powered transient X-ray pulsar KS 1947+300 carried out during the declining phase of its 2000 November -- 2001 June outburst. A detailed spectral study of KS 1947+300 across a wide X-ray band (0.1--100.0 keV) is attempted for the first time here. Timing analysis of the data clearly shows a 18.7 s pulsation in the X-ray light curves in the above energy band. The pulse profile of KS 1947+300 is characterized by a broad peak with sharp rise followed by a narrow dip. The dip in the pulse profile shows a very strong energy dependence. Broad-band pulse-phase-averaged spectroscopy obtained with three of the BeppoSAX instruments shows that the energy spectrum in the 0.1--100 keV energy band has three components, a Comptonized component, a ~0.6 keV blackbody component, and a narrow and weak iron emission line at 6.7 keV with a low column density of material in the line of sight. We place an upper limit on the equivalent width of the iron K_\\...

  13. 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

    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...

  14. 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.

  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 monitoring tracing the evolution of the jet and disc in the black hole candidate X-ray binary MAXI J1659-152

    Science.gov (United States)

    van der Horst, A. J.; Curran, P. A.; Miller-Jones, J. C. A.; Linford, J. D.; Gorosabel, J.; Russell, D. M.; de Ugarte Postigo, A.; 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.

    2013-12-01

    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, submillimetre, 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 broad-band picture of the evolution of this outburst. We have performed broad-band spectral modelling, 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 disc 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/optical/UV-X-ray correlations up to ˜3 yr after the outburst onset to examine the link between the jet and the accretion disc, and found that there is no significant jet contribution to the nIR emission when the source is in the soft or intermediate X-ray spectral state, consistent with our detection of the jet break at radio frequencies during these states.

  17. Measurements of radio frequent cavity volt ages by X-ray spectrum measurements

    Directory of Open Access Journals (Sweden)

    Toprek Dragan

    2005-01-01

    Full Text Available This paper deals with X-ray spectrum measurement as a method for the measurement of radio frequent cavity voltage and the theory of X-ray spectrum calculation. Experimental results at 72 MHz for three different values of the radio frequent power of ACCEL K250 super conducting cyclotron are being presented.

  18. The Swift Burst Alert Telescope Detected Seyfert 1 Galaxies: X-Ray Broadband Properties and Warm Absorbers

    Science.gov (United States)

    Winter, Lisa M.; Veilleux, Sylvain; McKernan, Barry; Kallman, T.

    2012-01-01

    We present results from an analysis of the broadband, 0.3-195 keV, X-ray spectra of 48 Seyfert 1-1.5 sources detected in the very hard X-rays with the Swift Burst Alert Telescope (BAT). This sample is selected in an all-sky survey conducted in the 14-195 keV band. Therefore, our sources are largely unbiased toward both obscuration and host galaxy properties. Our detailed and uniform model fits to Suzaku/BAT and XMM-Newton/BAT spectra include the neutral absorption, direct power-law, reflected emission, soft excess, warm absorption, and narrow Fe I K[alpha] emission properties for the entire sample. We significantly detect O VII and O VIII edges in 52% of our sample. The strength of these detections is strongly correlated with the neutral column density measured in the spectrum. Among the strongest detections, X-ray grating and UV observations, where available, indicate outflowing material. The ionized column densities of sources with O VII and O VIII detections are clustered in a narrow range with Nwarm [approx] 1021 cm-2, while sources without strong detections have column densities of ionized gas an order of magnitude lower. Therefore, we note that sources without strong detections likely have warm ionized outflows present but at low column densities that are not easily probed with current X-ray observations. Sources with strong complex absorption have a strong soft excess, which may or may not be due to difficulties in modeling the complex spectra of these sources. Still, the detection of a flat [Gamma] [approx] 1 and a strong soft excess may allow us to infer the presence of strong absorption in low signal-to-noise active galactic nucleus spectra. Additionally, we include a useful correction from the Swift BAT luminosity to bolometric luminosity, based on a comparison of our spectral fitting results with published spectral energy distribution fits from 33 of our sources.

  19. X-ray emission from open star clusters with Spectrum-Rontgen-Gamma

    DEFF Research Database (Denmark)

    Singh, K.P.; Ojha, D.K.; Schnopper, H.W.;

    1998-01-01

    The study of X-ray emission from co-evolving populations of stars in open dusters is extremely important for understanding the dynamo activity among the stars. With this objective, we propose to observe a number of open clusters in the X-ray and UV bands using SPECTRUM-Rontgen-Gamma. The high...... throughput of SPECTRUM-Rontgen-Gamma will help detect main sequence stars like Sun in middle-aged and old clusters. We will study the relationships between various parameters - age, rotation, abundance, UBV colors, X-ray luminosity, coronal temperature etc. X-ray spectra of younger and brighter populations...

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

    International Nuclear Information System (INIS)

    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 L3-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

  1. ASCA observations of deep ROSAT fields V. The X-ray spectrum of hard X-ray selected QSOs

    CERN Document Server

    Pappa, A; Georgantopoulos, I; Griffiths, R E; Boyle, B J; Shanks, T

    2001-01-01

    We present an analysis of the \\rosat and \\asca spectra of 21 broad line AGN (QSOs) with $z\\sim 1$ detected in the 2-10 keV band with the \\asca \\gis. The summed spectrum in the \\asca band is well described by a power-law with $\\Gamma=1.56\\pm0.18$, flatter that the average spectral index of bright QSOs and consistent with the spectrum of the X-ray background in this band. The flat spectrum in the \\asca band could be explained by only a moderate absorption ($\\sim 10^{22} \\rm cm^{-2}$) assuming the typical AGN spectrum ie a power-law with $\\Gamma$=1.9. This could in principle suggest that some of the highly obscured AGN, required by most X-ray background synthesis models, may be associated with normal blue QSOs rather than narrow-line AGN. However, the combined 0.5-8 keV \\asca-\\rosat spectrum is well fit by a power-law of $\\Gamma=1.7\\pm0.2$ with a spectral upturn at soft energies. It has been pointed out that such an upturn may be an artefact of uncertainties in the calibration of the ROSAT or ASCA detectors. Nev...

  2. INTEGRAL discovery of unusually long broad-band X-ray activity from the Supergiant Fast X-ray Transient IGR J18483-0311

    CERN Document Server

    Sguera, V; Bird, A J; Bazzano, A

    2015-01-01

    We report on a broad-band X-ray study (0.5-250 keV) of the Supergiant Fast X-ray Transient IGR J18483-0311 using archival INTEGRAL data and a new targeted XMM-Newton observation. Our INTEGRAL investigation discovered for the first time an unusually long X-ray activity (3-60 keV) which continuously lasted for at least 11 days, i.e. a significant fraction (about 60%) of the entire orbital period, and spanned orbital phases corresponding to both periastron and apastron passages. This prolongated X-ray activity is at odds with the much shorter durations marking outbursts from classical SFXTs especially above 20 keV, as such it represents a departure from their nominal behavior and it adds a further extreme characteristic to the already extreme SFXT IGR J18483-0311. Our IBIS/ISGRI high energy investigation (100-250 keV) of archival outbursts activity from the source showed that the recently reported hint of a possible hard X-ray tail is not real and it is likely due to noisy background. The new XMM-Newton targeted...

  3. Development of multilayer optics for X-ray broadband spectrometry of plasma emission

    International Nuclear Information System (INIS)

    Within the framework of the research on inertial confinement fusion, the 'Commissariat a l'energie atomique et aux energies alternatives' has studied and implemented an absolute calibrated time-Resolved broadband soft x-Ray spectrometer, called 'Diagnostic de Mesure du rayonnement X'. This diagnostic, composed of 20 measurement channels, measures the emitted radiant power from a laser created plasma in the range from 50 eV to 20 keV. We have developed additional measurement channels to obtain redundancy and an improvement in measurement accuracy. The principle of these new channels is based on an original concept to obtain spectral bounded flat-Responses. Two channels have been developed for the 2 - 4 keV and 4 - 6 keV spectral ranges, using aperiodic multilayer mirrors made at the 'Laboratoire Charles Fabry' with Cr/Sc and Ni/W/SiC/W layers respectively. These mirrors were characterized at synchrotron radiation facilities and integrated into the spectrometer. The two new channels were used during laser-Plasma experimental campaigns at the OMEGA laser facility in Rochester (USA). This allowed us to determine directly the radiant power with only one measurement within a certain spectral band, and with a better precision when compared with using standard channels. The results, in good agreement with the standard measurement channels, allowed us to validate the use of aperiodic multilayer mirrors for X-Ray broadband spectrometry. (author)

  4. The First High Resolution X-ray Spectrum of Cyg X-1: Soft X-Ray Ionization and Absorption

    OpenAIRE

    Schulz, N. S.; Cui, W.; Canizares, C. R.; Marshall, H. L.; Lee, J. C.; Miller, J.M.; Lewin, W. H. G.

    2001-01-01

    We observed the black hole candidate Cyg X-1 for 15 ks with the High-Energy Transmission Grating Spectrometer aboard the CHANDRA X-ray Observatory. The source was observed during a period of intense flaring activity, so it was about a factor of 2.5 brighter than usual, with a 0.5-10 keV (1-24 A) luminosity of 1.6x10^37 erg/s (at a distance of 2.5 kpc). The spectrum of the source shows prominent absorption edges, some of which have complicated substructure. We use the most recent results from ...

  5. 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 ...

  6. 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-ray ...... 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.......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...

  7. Suzaku observations of the hard X-ray spectrum of Vela Jr

    CERN Document Server

    Takeda, Sawako; Terada, Yukikatsu; Tashiro, Makoto S; Katsuda, Satoru; Yamazaki, Ryo; Ohira, Yutaka; Iwakiri, Wataru

    2016-01-01

    We report the results of Suzaku observations of the young supernova remnant, Vela Jr.\\ (RX J0852.0$-$4622), which is known to emit synchrotron X-rays, as well as TeV gamma-rays. Utilizing 39 Suzaku mapping observation data from Vela Jr., a significant hard X-ray emission is detected with the hard X-ray detector (HXD) from the north-west TeV-emitting region. The X-ray spectrum is well reproduced by a single power-law model with the photon index of 3.15$^{+1.18}_{-1.14}$ in the 12--22 keV band. Compiling this with the soft X-ray spectrum simultaneously observed with the X-ray imaging spectrometer (XIS) onboard Suzaku, we find that the wide-band X-ray spectrum in the 2--22 keV band is reproduced with a single power-law or concave broken power-law model, which are statistically consistent with each other. Whichever the model of a single or broken power-law is appropriate, clearly the spectrum has no rolloff structure. Applying this result to the method introduced in \\citet{yama2014}, we find that one-zone synchro...

  8. First X-ray observations of Low-Power Compact Steep Spectrum Sources

    CERN Document Server

    Kunert-Bajraszewska, M; Siemiginowska, A; Guainazzi, M

    2013-01-01

    We report first X-ray Chandra observations of a sample of seven low luminosity compact (LLC) sources. They belong to a class of young compact steep spectrum (CSS) radio sources. Four of them have been detected, the other three have upper limit estimations for X-ray flux, one CSS galaxy is associated with an X-ray cluster. We have used the new observations together with the observational data for known strong CSS and gigahertz-peaked spectrum (GPS) objects and large scale FRIs and FRIIs to study the relation between morphology, X-ray properties and excitation modes in radio-loud AGNs. We found that: (1) The low power objects fit well to the already established X-ray - radio luminosity correlation for AGNs and occupy the space among, weaker in the X-rays, FRI objects. (2) The high excitation galaxies (HEG) and low excitation galaxies (LEG) occupy distinct locus in the radio/X-ray luminosity plane, notwithstanding their evolutionary stage. This is in agreement with the postulated different origin of the X-ray em...

  9. X-ray spectrum estimation from transmission measurements by an exponential of a polynomial model

    Science.gov (United States)

    Perkhounkov, Boris; Stec, Jessika; Sidky, Emil Y.; Pan, Xiaochuan

    2016-04-01

    There has been much recent research effort directed toward spectral computed tomography (CT). An important step in realizing spectral CT is determining the spectral response of the scanning system so that the relation between material thicknesses and X-ray transmission intensity is known. We propose a few parameter spectrum model that can accurately model the X-ray transmission curves and has a form which is amenable to simultaneous spectral CT image reconstruction and CT system spectrum calibration. While the goal is to eventually realize the simultaneous image reconstruction/spectrum estimation algorithm, in this work we investigate the effectiveness of the model on spectrum estimation from simulated transmission measurements through known thicknesses of known materials. The simulated transmission measurements employ a typical X-ray spectrum used for CT and contain noise due to the randomness in detecting finite numbers of photons. The proposed model writes the X-ray spectrum as the exponential of a polynomial (EP) expansion. The model parameters are obtained by use of a standard software implementation of the Nelder-Mead simplex algorithm. The performance of the model is measured by the relative error between the predicted and simulated transmission curves. The estimated spectrum is also compared with the model X-ray spectrum. For reference, we also employ a polynomial (P) spectrum model and show performance relative to the proposed EP model.

  10. X-ray variability of 104 active galactic nuclei. XMM-Newton power-spectrum density profiles

    Science.gov (United States)

    Gonzalez-Martin, Omaira; Vaughan, Simon; de la Cierva, Juan

    2012-09-01

    Active galactic nuclei (AGN), powered by accretion onto supermassive black holes (SMBHs), are thought to be scaled up versions of Galactic black hole X-ray binaries (BH-XRBs). In the past few years evidence of such correspondence include similarities in the broadband shape of the X-ray variability power spectra, with characteristic bend times-cales scaling with mass. We have characterized the X-ray temporal properties of a sample of AGN to study the connection among different classes of AGN and their connection with BH-XRBs. We have performed a uniform analysis of the power spectrum densities (PSDs) of 104 nearby (zfundamental plane" relating variability timescale, black hole mass, and luminosity is studied using the new X-ray timing results presented here together with a compilation of the previously detected timescales from the literature. Both quantitative (i.e. scaling with BH mass) and qualitative (overall PSD shapes) found in this sample of AGN are in agreement with the expectations for the SMBHs and BH-XRBs being the same phenomenon scaled-up with the size of the BH. The steep PSD slopes above the high frequency bend bear a closer resemblance to those of the "soft/thermal dominated" BH- XRB states than other states.

  11. The First High Resolution X-ray Spectrum of Cyg X-1 Soft X-Ray Ionization and Absorption

    CERN Document Server

    Schulz, N S; Canizares, C R; Marshall, H L; Lee, J C; Miller, J M; Lewin, W H G

    2002-01-01

    We observed the black hole candidate Cyg X-1 for 15 ks with the High-Energy Transmission Grating Spectrometer aboard the CHANDRA X-ray Observatory. The source was observed during a period of intense flaring activity, so it was about a factor of 2.5 brighter than usual, with a 0.5-10 keV (1-24 A) luminosity of 1.6x10^37 erg/s (at a distance of 2.5 kpc). The spectrum of the source shows prominent absorption edges, some of which have complicated substructure. We use the most recent results from laboratory measurements and and calculations to model the observed substructure of the edges. From the model, we derive a total absorption column of 6.21+/-0.22 10^21 cm^-2. Furthermore, the results indicate that there are ~ 10 - 25% abundance variations relative to solar values for neon, oxygen and iron. The X-ray continuuum is described well by a two-component model that is often adopted for black hole candidates: a soft multicolor disk component (with kT = 203 eV) and a hard power law component (with a photon index of ...

  12. The X-ray view of Giga-Hertz Peaked Spectrum Radio Galaxies

    CERN Document Server

    Tengstrand, Olof; Siemiginowska, A; Bonilla, N Fonseca; Labiano, A; Worrall, D M; Grandi, P; Piconcelli, E

    2009-01-01

    This paper presents the X-ray properties of a flux- and volume-limited complete sample of 16 Giga-Hertz Peaked Spectrum (GPS) galaxies. This study addresses three basic questions in our understanding of the nature and evolution of GPS sources: a) What is the physical origin of the X-ray emission in GPS galaxies? b) Which physical system is associated with the X-ray obscuration? c) What is the "endpoint" of the evolution of compact radio sources? We obtain a 100% (94%) detection fraction in the 0.5-2 keV (0.5-10 keV) energy band. GPS galaxy X-ray spectra are typically highly obscured. The X-ray column density is larger than the HI column density measured in the radio by a factor 10 to 100. GPS galaxies lie well on the extrapolation to high radio powers of the correlation between radio and X-ray luminosity known in low-luminosity FRI radio galaxies. On the other hand, GPS galaxies exhibit a comparable X-ray luminosity to FRII radio galaxies, notwithstanding their much larger radio luminosity. The X-ray to radio...

  13. 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...

  14. X-ray Properties of the GigaHertz-Peaked and Compact Steep Spectrum Sources

    CERN Document Server

    Siemiginowska, Aneta; Aldcroft, Thomas L; Bechtold, Jill; Elvis, Martin

    2008-01-01

    We present {\\it Chandra} X-ray Observatory observations of Giga-Hertz Peaked Spectrum (GPS) and Compact Steep Spectrum (CSS) radio sources. The {\\it Chandra} sample contains 13 quasars and 3 galaxies with measured 2-10 keV X-ray luminosity within $10^{42} - 10^{46}$ erg s$^{-1}$. We detect all of the sources, five of which are observed in X-ray for the first time. We study the X-ray spectral properties of the sample. The measured absorption columns in the quasars are different than those in the galaxies in the sense that the quasars show no absorption (with limits $\\sim 10^{21} \\rm cm^{-2}$) while the galaxies have large absorption columns ($> 10^{22} \\rm cm^{-2}$) consistent with previous findings. The median photon index of the sources with high S/N is $\\Gamma=1.84 \\pm0.24$ and it is larger than the typical index of radio loud quasars. The arcsec resolution of {\\it Chandra} telescope allows us to investigate X-ray extended emission, and look for diffuse components and X-ray jets. We found X-ray jets in two ...

  15. Research of laser plasma X-ray spectrum from spherical targets

    Energy Technology Data Exchange (ETDEWEB)

    Gasparyan, P.D. [RFNC-VNIIEF, Mira Avenue 37, 607190 Sarov (Russian Federation); Gusikhina, I.A. [RFNC-VNIIEF, Mira Avenue 37, 607190 Sarov (Russian Federation); Lobanova, Yu.L. [RFNC-VNIIEF, Mira Avenue 37, 607190 Sarov (Russian Federation); Zhidkov, N.V. [RFNC-VNIIEF, Mira Avenue 37, 607190 Sarov (Russian Federation); Subbotin, A.N. [RFNC-VNIIEF, Mira Avenue 37, 607190 Sarov (Russian Federation)]. E-mail: subbotin@otd470.vniief.ru; Tsoi, E.S. [RFNC-VNIIEF, Mira Avenue 37, 607190 Sarov (Russian Federation)

    2007-05-21

    The paper describes the results of measurements carried out at VNIIEF on a laser facility ISKRA-5 with spherical targets of different type. Spectra of X-rays are measured with the aid of cylindrical Ni/C multilayer mirror (MM). To absolutely normalize the results of spectral measurements, there is additionally registered X-rays by semiconductor detectors with different filters. Detectors' serviceability at operation in the mode of deep current saturation is demonstrated. Experimental and calculation data of spectrum of target X-rays are presented and compared.

  16. The CHANDRA HETGS X-ray Grating Spectrum of Eta Car

    OpenAIRE

    Corcoran, M. F; Swank, J.H.; Petre, R.; Ishibashi, K.; Davidson, K.; Townsley, L.; Smith, R.; S. White; Viotti, R; A. Damineli

    2001-01-01

    Eta Car may be the most massive and luminous star in the Galaxy and is suspected to be a massive, colliding wind binary system. The CHANDRA X-ray observatory has obtained a calibrated, high-resolution X-ray spectrum of the star uncontaminated by the nearby extended soft X-ray emisssion. Our 89 ksec CHANDRA observation with the High Energy Transmission Grating Spectrometer (HETGS) shows that the hot gas near the star is non-isothermal. The temperature distribution may represent the emission on...

  17. Modulations of broad-band radio continua and X-ray emissions in the large X-ray flare on 03 November 2003

    Science.gov (United States)

    Dauphin, C.; Vilmer, N.; Lüthi, T.; Trottet, G.; Krucker, S.; Magun, A.

    The GOES X3.9 flare on 03 November 2003 at ˜09:45 UT was observed from metric to millimetric wavelengths by the Nançay Radioheliograph (NRH), the Radio Solar Telescope Network (RSTN) and by radio instruments operated by the Institute of Applied Physics (University of Bern). This flare was simultaneously observed and imaged up to several 100 keV by the RHESSI experiment. The time profile of the X-ray emission above 100 keV and of the radio emissions shows two main parts, impulsive emission lasting about 3 min and long duration emission (partially observed by RHESSI) separated in time by 4 min. We shall focus here on the modulations of the broad-band radio continua and of the X-ray emissions observed in the second part of the flare. The observations suggest that gyrosynchrotron emission is the prevailing emission mechanism even at decimetric wavelengths for the broad-band radio emission. Following this interpretation, we deduce the density and the magnetic field of the decimetric sources and briefly comment on possible interpretations of the modulations.

  18. 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.

  19. The X-ray spectrum of RX J1914.4+2456 revisited

    CERN Document Server

    Ramsay, Gavin

    2007-01-01

    It has been proposed that RX J1914.4+2456 is a stellar binary system with an orbital period of 9.5 mins. As such it shares many similar properties with RX J0806.3+1527 (5.4 mins). However, while the X-ray spectrum of RX J0806.3+1527 can be modelled using a simple absorbed blackbody, the X-ray spectrum of RX J1914.4+2456 has proved difficult to fit using a physically plausible model. In this paper we re-examine the available X-ray spectra of RX J1914.4+2456 taken using XMM-Newton. We find that the X-ray spectra can be fitted using a simple blackbody and an absorption component which has a significant enhancement of neon compared to the solar value. We propose that the material in the inter-binary system is significantly enhanced with neon. This makes its intrinsic X-ray spectrum virtually identical to RX J0806.3+1527. We re-access the X-ray luminosity of RX J1914.4+2456 and the implications of these results.

  20. Broadband observations of the X-ray burster 4U1705-44 with BeppoSAX

    Science.gov (United States)

    Piraino, S.; Santangelo, A.; Mück, B.; Kaaret, P.; Di Salvo, T.; D'Aì, A.; Iaria, R.; Egron, E.

    2016-06-01

    Context. 4U1705-44 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. Aims: 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. Methods: Using two BeppoSAX observations carried out in August and October 2000, respectively, for a total effective exposure time of ~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 components observed are the soft Comptonization and hard Comptonization, the blackbody, and a reflection component with a broad iron line. When the source moves from the banana state to the island state, the parameters of the two Comptonization components change significantly and the blackbody component becomes too weak to be detected. Conclusions: We interpret the soft Comptonization component as emission from the hot plasma surrounding the neutron star, hard Comptonization as emission from the disk region, and the blackbody component as emission from the inner accretion disk. The broad feature in the iron line region is compatible with reflection from the inner accretion disk.

  1. Behavior of the x-ray spectrum of multiply charged ions during forced plasma expansion

    Energy Technology Data Exchange (ETDEWEB)

    Zhidkov, A.G.; Marchenko, V.S.

    1982-07-01

    The behavior of the x-ray emission spectrum of a dense plasma during forced expansion is studied. The optical transparency of the plasma varies during the expansion. The plasma emission spectrum integrated over the expansion time is calculated from the analytic solutions of the equations. The intensity of the line emission is calculated in the average-ion approximation.

  2. A Coordinated X-ray and Optical Campaign on the Nearest Massive Eclipsing Binary, Delta Ori Aa: I. Overview of the X-ray Spectrum

    CERN Document Server

    Corcoran, M F; Pablo, H; Shenar, T; Pollock, A M T; Waldron, W L; Moffat, A F J; Richardson, N D; Russell, C M P; Hamaguchi, K; Huenemoerder, D P; Oskinova, L; Hamann, W -R; Naze, Y; Ignace, R; Evans, N R; Lomax, J R; Hoffman, J L; Gayley, K; Owocki, S P; Leutenegger, M; Gull, T R; Hole, K T; Lauer, J; Iping, R C

    2015-01-01

    We present an overview of four phase-constrained Chandra HETGS X-ray observations of Delta Ori A. Delta Ori A is actually a triple system which includes the nearest massive eclipsing spectroscopic binary, Delta Ori Aa, the only such object which can be observed with little phase-smearing with the Chandra gratings. Since the fainter star, Delta Ori Aa2, has a much lower X-ray luminosity than the brighter primary, Delta Ori A provides a unique system with which to test the spatial distribution of the X-ray emitting gas around Delta Ori Aa1 via occultation by the photosphere of and wind cavity around the X-ray dark secondary. Here we discuss the X-ray spectrum and X-ray line profiles for the combined observation, having an exposure time of nearly 500 ksec and covering nearly the entire binary orbit. Companion papers discuss the X-ray variability seen in the Chandra spectra, present new space-based photometry and ground-based radial velocities simultaneous with the X-ray data to better constrain the system parame...

  3. Deconstructing the Spectrum of the Soft X-ray Background

    Science.gov (United States)

    Kuntz, K. D.; Snowden, S. L.

    2000-01-01

    The soft X-ray background in the 0.1-1.0 keV band is known to be produced by at least three sources; the Local Hot Bubble (LHB), the extragalactic power law (EPL), and a seemingly galactic component that lies outside the bulk of the absorption that is due to the ISM of the galactic disk. This last component, which we call the Trans-Absorption Emission (TAE), has been modeled by a number of groups who have derived disparate measures of its temperature. The differences have arisen from differing assumptions about the structure of the emitting gas and unrecognized methodological difficulties. In particular, spectral fitting methods do not uniquely separate the TAE from the foreground emission that is due the LHB. This "degeneracy" can be resolved using the angular variation of the absorption of the TAE. We show that the TAE cannot be characterized by a single thermal component; no single-component model can be consistent with both the spectral energy distribution of the TAE emission and the angular variation due to absorption by the galactic disk. We use the angular anticorrelation of the ROSAT All-Sky Survey with the galactic absorption to separate local from distant emission components, and to fit the spectral energy distribution of the resulting distant emission. We find that the emission is best described by a two-thermal-component model with logT(sub S) = 6.06(sup +0.14, sub -0.12) and log T(sub H) = 6.42(sup +0.14, sub -0.12). This two-thermal-component TAE fits the ROSAT spectral energy distribution significantly better than single-component models, and is consistent with both angular variation and spectral constraints.

  4. Reconstruction of the X-ray tube spectrum from a scattering measurement

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, Jorge E., E-mail: jorge.fernandez@unibo.it [Laboratory of Montecuccolino, Department of Energy, Nuclear and Environmental Control Engineering (DIENCA), Alma Mater Studiorum University of Bologna, via dei Colli,16, I-40136, Bologna (Italy); Scot, Viviana [Laboratory of Montecuccolino, Department of Energy, Nuclear and Environmental Control Engineering (DIENCA), Alma Mater Studiorum University of Bologna, via dei Colli,16, I-40136, Bologna (Italy); Bare, Jonathan [Laboratory of Montecuccolino, Department of Energy, Nuclear and Environmental Control Engineering (DIENCA), Alma Mater Studiorum University of Bologna, via dei Colli,16, I-40136, Bologna (Italy); Laboratory of Nuclear and Radiological Physics, Institut Superieur Industriel de Bruxelles (ISIB) (Belgium); Tondeur, Francois [Laboratory of Nuclear and Radiological Physics, Institut Superieur Industriel de Bruxelles (ISIB) (Belgium); Gallardo, Sergio; Rodenas, Jose [Department of Chemical and Nuclear Engineering, Polytechnic University of Valencia (Spain); Rossi, Pier Luca [Operational Unit of Health Physics, Alma Mater Studiorum University of Bologna (Italy)

    2012-07-15

    An inverse technique has been designed to unfold the x-ray tube spectrum from the measurement of the photons scattered by a target interposed in the path of the beam. A special strategy is necessary to circumvent the ill-conditioning of the forward transport algebraic problem. The proposed method is based on the calculation of both, the forward and adjoint analytical solutions of the Boltzmann transport equation. After testing the method with numerical simulations, a simple prototype built at the Operational Unit of Health Physics of the University of Bologna was used to test the method experimentally. The reconstructed spectrum was validated by comparison with a straightforward measurement of the X-ray beam. The influence of the detector was corrected in both cases using standard unfolding techniques. The method is capable to accurately characterize the intensity distribution of an X-ray tube spectrum, even at low energies where other methods fail. - Highlights: Black-Right-Pointing-Pointer A complete inverse technique of source unfolding is presented. Black-Right-Pointing-Pointer The X-ray tube spectrum is recovered from a scattering measurement. Black-Right-Pointing-Pointer The ill conditioning of the plain forward transport algebraic problem is avoided. Black-Right-Pointing-Pointer Forward and adjoint solutions of the Boltzmann transport equation are used. Black-Right-Pointing-Pointer The technique characterizes X-ray tube spectra even at low energies.

  5. The soft quiescent spectrum of the transiently accreting 11-Hz X-ray pulsar in the globular cluster Terzan 5

    NARCIS (Netherlands)

    N. Degenaar; R. Wijnands

    2011-01-01

    We report on the quiescent X-ray properties of the recently discovered transiently accreting 11-Hz X-ray pulsar in the globular cluster Terzan 5. Using two archival Chandra observations, we demonstrate that the quiescent spectrum of this neutron star low-mass X-ray binary is soft and can be fit to a

  6. The broadband spectrum of Centaurus X-3

    Science.gov (United States)

    Gottlieb, Amy; Pottschmidt, Katja; Marcu, Diana; Wolff, Michael Thomas; Kühnel, Matthias; Falkner, Sebastian; Britton Hemphill, Paul; Suchy, Slawomir; Becker, Peter A.; Wood, Kent S.; Wilms, Joern

    2016-04-01

    We present an analysis of a Suzaku observation of the accreting pulsar and high mass X-ray binary Centaurus X-3. The observation was performed in 2008 and covers one 2.1 day binary orbit. Strong flux and hardness variability is present in the energy range from 0.8 to 60 keV. We selected a part of the observation covering ~40% of the first half of the orbit during which the spectral shape was stable and less absorbed than during other parts of the observation. We confirm earlier results that the broadband spectrum can be modeled with acutoff power law modified by a partial absorber, three iron lines -- from near-neutral, helium-like, and hydrogen-like iron --, and a cyclotron resonant scattering line at 30 keV. The pulse profile shows a shift above the cyclotron line energy which is qualitatively consistent with recent theoretical predictions. In addition we findthat the presence of the so-called ``13 keV'' bump is model dependent and that there are indications for further line-like spectral components at 1 keV and 6 keV and a broader residual around 2 keV. We also apply the newly implemented radiation dominated radiative shock model for luminous accretion pulsars by Becker and Wolff (2007, ApJ 654, 435) to model the broadband spectrum. Replacing the cutoff power law with the physical continuum while retaining all other components we obtain a similar goodness of fit as before. From the physical continuum model we determine a mass accretion rate of ~2.17 x 10^17 g/s, an accretion column radius of 65 (+12, -4) m, and a temperature of the accreted plasma of 3.1 (+0.4, -0.1) keV.

  7. 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...

  8. The Hard X-Ray Spectrum of NGC 1365: Scattered Light, Not Black Hole Spin

    Science.gov (United States)

    Miller, L.; Turner, T. J.

    2013-08-01

    Active galactic nuclei (AGNs) show excess X-ray emission above 10 keV compared with extrapolation of spectra from lower energies. Risaliti et al. have recently attempted to model the hard X-ray excess in the type 1.8 AGN NGC 1365, concluding that the hard excess most likely arises from Compton-scattered reflection of X-rays from an inner accretion disk close to the black hole. Their analysis disfavored a model in which the hard excess arises from a high column density of circumnuclear gas partially covering a primary X-ray source, despite such components being required in the NGC 1365 data below 10 keV. Using a Monte Carlo radiative transfer approach, we demonstrate that this conclusion is invalidated by (1) use of slab absorption models, which have unrealistic transmission spectra for partial covering gas, (2) neglect of the effect of Compton scattering on transmitted spectra, and (3) inadequate modeling of the spectrum of scattered X-rays. The scattered spectrum is geometry-dependent and, for high global covering factors, may dominate above 10 keV. We further show that, in models of circumnuclear gas, the suppression of the observed hard X-ray flux by reprocessing may be no larger than required by the "light bending" model invoked for inner disk reflection, and the expected emission line strengths lie within the observed range. We conclude that the time-invariant "red wing" in AGN X-ray spectra is probably caused by continuum transmitted through and scattered from circumnuclear gas, not by highly redshifted line emission, and that measurement of black hole spin is not possible.

  9. The hard X-ray spectrum of NGC 1365: scattered light, not black hole spin

    CERN Document Server

    Miller, L

    2013-01-01

    Active Galactic Nuclei (AGN) show excess X-ray emission above 10 keV compared with extrapolation of spectra from lower energies. Risaliti et al. have recently attempted to model the hard X-ray excess in the type 1.8 AGN NGC 1365, concluding that the hard excess most likely arises from Compton-scattered reflection of X-rays from an inner accretion disk close to the black hole. Their analysis disfavored a model in which the hard excess arises from a high column density of circumnuclear gas partially covering a primary X-ray source, despite such components being required in the NGC 1365 data below 10 keV. Using a Monte Carlo radiative transfer approach, we demonstrate that this conclusion is invalidated by (i) use of slab absorption models, which have unrealistic transmission spectra for partial covering gas, (ii) neglect of the effect of Compton scattering on transmitted spectra and (iii) inadequate modeling of the expected spectrum of scattered X-rays. The scattered spectrum is geometry dependent and, for high...

  10. Selectivity and efficiency of pyrene attachment to alkanes induced by broadband X-rays

    Directory of Open Access Journals (Sweden)

    GERALD O. BROWN

    2003-03-01

    Full Text Available Bombardment of pyrene-doped n-heneicosane (C21H44 in its orthorhombic solid phase with MeV broadband X-rays results in the formation of both mono- and di-heneicosylpyrenes, whereas the same dose in liquid cyclohexane yields only monosubstituted pyrene. In both cases, the reaction efficiency decreases as pyrene concentration is increased from 10-5 to 10-2 M. Qualitatively, the overall attachment efficiency is higher in orthorhombic n-heneicosane than in liquid cyclohexane, but the selectivity of attachment is greater in cyclohexane. Differences between these results and those from irradiations of the same samples with eV range photons are discussed.A exposição de n-heneicosano (C21H44 dopado com pireno, em sua fase ortorrômbica sólida, a Raios X de faixa larga a MeV resulta na formação de mono- e di-heneicosilpirenos, enquanto que a mesma dose em ciclo-hexano líquido produz apenas pireno monossubstituído. Em ambos os casos, a eficiência da reação diminui quando a concentração de pireno aumenta de 10-5 a 10-2 M. Qualitativamente, a eficiência global de ligação é maior em n-heneicosano ortorrômbico do que em ciclohexano líquido, mas a seletividade de ligação é maior em ciclo-hexano. As diferenças entre estes resultados e os de irradiação das mesmas amostras com fotons na faixa de eV são discutidas.

  11. A phenomenological model for the X-ray spectrum of Nova V2491 Cygni

    CERN Document Server

    Pinto, Ciro; Verbunt, Frank; Kaastra, Jelle S; Costantini, Elisa; Detmers, Rob G

    2012-01-01

    The X-ray flux of Nova V2491 Cyg reached a maximum some forty days after optical maximum. The X-ray spectrum at that time, obtained with the RGS of XMM-Newton, shows deep, blue-shifted absorption by ions of a wide range of ionization. We show that the deep absorption lines of the X-ray spectrum at maximum, and nine days later, are well described by the following phenomenological model with emission from a central blackbody and from a collisionally ionized plasma (CIE). The blackbody spectrum (BB) is absorbed by three main highly-ionized expanding shells; the CIE and BB are absorbed by cold circumstellar and interstellar matter that includes dust. The outflow density does not decrease monotonically with distance. The abundances of the shells indicate that they were ejected from an O-Ne white dwarf. We show that the variations on time scales of hours in the X-ray spectrum are caused by a combination of variation in the central source and in the column density of the ionized shells. Our phenomenological model gi...

  12. Image enhancement of x-ray microscope using frequency spectrum analysis

    Energy Technology Data Exchange (ETDEWEB)

    Li Wenjie; Chen Jie; Tian Jinping; Zhang Xiaobo; Liu Gang; Tian Yangchao [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029 (China); Liu Yijin; Wu Ziyu, E-mail: wuzy@ihep.ac.c, E-mail: ychtian@ustc.edu.c [Institute of High Energy Physics, Chinese Academy of Science, Beijing 100049 (China)

    2009-09-01

    We demonstrate a new method for x-ray microscope image enhancement using frequency spectrum analysis. Fine sample characteristics are well enhanced with homogeneous visibility and better contrast from single image. This method is easy to implement and really helps to improve the quality of image taken by our imaging system.

  13. Understanding the X-ray spectrum of anomalous X-ray pulsars and soft gamma-ray repeaters

    International Nuclear Information System (INIS)

    Hard X-rays above 10 keV are detected from several anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs), and different models have been proposed to explain the physical origin within the frame of either a magnetar model or a fallback disk system. Using data from Suzaku and INTEGRAL, we study the soft and hard X-ray spectra of four AXPs/SGRs: 1RXS J170849−400910, 1E 1547.0−5408, SGR 1806−20 and SGR 0501+4516. It is found that the spectra could be well reproduced by the bulk-motion Comptonization (BMC) process as was first suggested by Trümper et al., showing that the accretion scenario could be compatible with X-ray emission from AXPs/SGRs. Simulated results from the Hard X-ray Modulation Telescope using the BMC model show that the spectra would have discrepancies from the power-law, especially the cutoff at ∼200 keV. Thus future observations will allow researchers to distinguish different models of the hard X-ray emission and will help us understand the nature of AXPs/SGRs. (paper)

  14. X-ray outflows of active galactic nuclei warm absorbers: A 900 ks Chandra simulated spectrum

    OpenAIRE

    Ramirez-Velasquez, J. M.; Garcia, J.

    2016-01-01

    We report on the performance of the statistical, X-ray absorption lines identification procedure XLINE-ID. As illustration, it is used to estimate the time averaged gas density $n_H(r)$ of a representative AGN's warm absorber ($T\\approx 10^5$~K) X-ray simulated spectrum. The method relies on three key ingredients: (1) a well established emission continuum level; (2) a robust grid of photoionisation models spanning several orders of magnitude in gas density ($n_H$), plasma column density ($N_H...

  15. A theoretical method based on Fourier spectrum analysis for the focusing performances of the X-ray compound refractive lenses

    Institute of Scientific and Technical Information of China (English)

    Jian Ye(叶坚); Zichun Le(乐孜纯); Jingqiu Liang(梁静秋); Kai Liu(刘恺); Bisheng Quan(全必胜); Yali Qin(覃亚丽); Guangxin Zhu(朱广信)

    2004-01-01

    It is important to predict the intensity distribution in focusing plane for designing the X-ray compound refractive lenses. On the basis of analyzing the structure of X-ray compound lenses and comparing it with Fraunhofer diffraction system, it is concluded that the X-ray focusing system can be regarded as a kind of Fraunhofer diffraction system. Therefore, a method based on Fourier spectrum analysis is presented to predict the intensity distribution in the focusing plane for the X-ray lenses. A brief analysis on the relationship between the parameters of X-ray lenses and their focusing performance is also given in this paper.

  16. X-ray outflows of active galactic nuclei warm absorbers: A 900 ks Chandra simulated spectrum

    CERN Document Server

    Ramirez-Velasquez, J M

    2016-01-01

    We report on the performance of the statistical, X-ray absorption lines identification procedure XLINE-ID. As illustration, it is used to estimate the time averaged gas density $n_H(r)$ of a representative AGN's warm absorber ($T\\approx 10^5$~K) X-ray simulated spectrum. The method relies on three key ingredients: (1) a well established emission continuum level; (2) a robust grid of photoionisation models spanning several orders of magnitude in gas density ($n_H$), plasma column density ($N_H$), and in ionization states; (3) theoretical curves of growth for a large set of atomic lines. By comparing theoretical and observed equivalent widths of a large set of lines, spanning highly ionized charge states from O, Ne, Mg, Si, S, Ar, and the Fe L-shell and K-shell, we are able to infer the location of the X-ray warm absorber.

  17. Simulations of X-ray spectrum and HVL for mammographic equipment using MCNP5 code

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Rafael Toledo F. de; Alvarez, Matheus; Velo, Alexandre F.; Oliveira, Marcela de; Miranda, Jose Ricardo A. [Universidade Estadual Paulista Julio de mesquita Filho (UNESP), Botucatu, SP (Brazil). Inst. de Biociencias de Botucatu. Dept. de Fisica e Biofisica; Pina, Diana R. [Universidade Estadual Paulista Julio de mesquita Filho (UNESP), Botucatu, SP (Brazil). Fac. de Medicina. Dept. de Doencas Tropicais e Diagnostico por Imagem

    2012-07-01

    Full text: The main goal of mammography is early detection of breast cancer. Thus, the mammograph should be designed so that the X-ray photons are emitted within an appropriate energy range, to distinguish the normal breast tissue and cancerous tissue. The distribution of the photons amount of X-ray beam, with their respective energies, is called the spectrum. From the spectrum it is possible to estimate the quality of the X-ray beam from the Half Value Layer (HVL). Objectives: This study aims to simulate the Senographe 600T mammography unit, manufactured by General Electric (GE), using the MCNP5 Monte Carlo code, to obtain its spectrum and HVL, and compare the HVL of the simulated model with experimental data. Method: the mammography unit was simulated using a simplified model which a beam of 2x10{sup 8} electrons focuses on a Mo target angled 12 degrees, within a capsule filled with vacuum. The incident electrons were converted into photons. The capsule has a beryllium window, allowing the passage of the X-ray beam. The beam is detected by an air cylinder with 1 cm thickness placed 60 cm from the target. On the path of X-ray beam, is inserted a 0.03 mm Mo filter located 1.6 cm after the beryllium window. The space between the capsule and the detector cylinder was filled with air. The quality of X-ray beam was verified from the HVL using the MCNP5 code and the experimental method for the voltage range typically used in clinical routine (26-31 kVp). Results and discussion: the X-ray spectrum of the mammography device is satisfactorily simulated by MCNP5, showing the characteristic radiation peaks of molybdenum at 17.479 keV and 19.602 keV, the filtered spectrum generated by Bremsstrahlung, and reducing the total number of photons with the decrease in applied tension (kVp). The HVL obtained by MCNP5 and experimental measurements show a maximum difference of 5.31% (for 31 kVp). The result of both methods are within acceptable limits established by national

  18. Constraining High Redshift X-ray Sources with Next Generation 21 cm Power Spectrum Measurements

    CERN Document Server

    Ewall-Wice, Aaron; Mesinger, Andrei; Dillon, Joshua S; Liu, Adrian; Pober, Jonathan

    2015-01-01

    We use the Fisher matrix formalism and semi-numerical simulations to derive quantitative predictions of the constraints that power spectrum measurements on next-generation interferometers, such as the Hydrogen Epoch of Reionization Array (HERA) and the Square Kilometre Array (SKA), will place on the characteristics of the X-ray sources that heated the high redshift intergalactic medium. Incorporating observations between $z=5$ and $z=25$, we find that the proposed 331 element HERA and SKA phase 1 will be capable of placing $\\lesssim 10\\%$ constraints on the spectral properties of these first X-ray sources, even if one is unable to perform measurements within the foreground contaminated "wedge" or the FM band. When accounting for the enhancement in power spectrum amplitude from spin temperature fluctuations, we find that the observable signatures of reionization extend well beyond the peak in the power spectrum usually associated with it. We also find that lower redshift degeneracies between the signatures of ...

  19. Shaping the X-ray spectrum of galaxy clusters with AGN feedback and turbulence

    CERN Document Server

    Gaspari, M; Ruszkowski, M

    2014-01-01

    The hot plasma filling galaxy clusters emits copious radiation in the X-ray band. The classic unheated and unperturbed cooling flow model predicts dramatic cooling rates and an isobaric X-ray spectrum with constant differential luminosity distribution, $dL_{\\rm x}/dT \\propto (T/T_{\\rm hot})^0$. Combining past observations, it is however clear that the cores of clusters (and groups) show a strong deficit of emission increasing toward the soft X-ray band: $dL_{\\rm x}/dT \\propto (T/T_{\\rm hot})^{\\alpha=2\\pm1}$. Using 3D hydrodynamic simulations, we show that the deficit arises from the competition of thermal instability condensation and AGN outflow injection. During tight self-regulated feedback, the average luminosity distribution slope is $\\alpha\\approx2$, oscillating within the observed $18$), while pure cooling drives a too shallow slope, $\\alpha<1$. We disentangle the role of heating and turbulence via controlled experiments. Distributed heating alone induces a declining X-ray spectrum with $1<\\alpha&...

  20. Observations of a hard X-ray component in the spectrum of Nova Ophiuchi

    Science.gov (United States)

    Wilson, C. K.; Rothschild, R. E.

    1983-01-01

    The spectrum and time variation of Nova Ophiuchi (H1705-25) in the 10-200 keV range as measured by the UCSD/MIT instruments aboard HEAO 1 during the period 1977 August 25 to September 28 are reported. The composite curve is best fitted by a kT = 2 keV thin thermal bremsstrahlung model below 10 keV and a separate hard X-ray component fitted equally well by a power-law component with photon index 2.19 + or - 0.06 or a kT = 32.1 + or - 2.4 keV thermal bremsstrahlung model. This is the first observation of a hard tail in the spectrum of a transient X-ray source with sufficient statistical significance to allow a detailed study of its spectral and temporal variability. It is found that the intensity variations of the high-energy X-rays are consistent with the variability at lower energies (3-6 keV), but no hard X-ray spectral index variability is found on time scales from 2 days to 2 weeks. The results can be interpreted as due to accretion onto a neutron star (or possibly onto a black hole) that may also be surrounded by an extended corona.

  1. The CHANDRA HETGS X-ray Grating Spectrum of Eta Carinae

    Science.gov (United States)

    Corcoran, M. F.; Swank, J. H.; Petre, R.; Ishibashi, K.; Davidson, K.; Townsley, L.; Smith, R.; White, S.; Viotti, R.; Damineli, A.; White, Nicholas E. (Technical Monitor)

    2001-01-01

    Eta Carinae may be the most massive and luminous star in the Galaxy and is suspected to be a massive, colliding wind binary system. The CHANDRA X-ray observatory has obtained a calibrated, high-resolution X-ray spectrum of the star uncontaminated by the nearby extended soft X-ray emission. Our 89 ksec CHANDRA observation with the High Energy Transmission Grating Spectrometer (HETGS) shows that the hot gas near the star is non-isothermal. The temperature distribution may represent the emission on either side of the colliding wind bow shock, effectively 'resolving' the shock. If so, the pre-shock wind velocities are approximately 700 and 1800 km/s in our analysis, and these velocities may be interpreted as the terminal velocities of the winds from 71 Carinae and from the hidden companion star. The forbidden-to-intercombination line ratios for the He-like ions of S, Si, and Fe are large, indicating that the line forming region lies far from the stellar photosphere. The iron fluorescent line at 1.93 angstroms, first detected by ASCA, is clearly resolved from the thermal iron line in the CHANDRA grating spectrum. The Fe fluorescent line is weaker in our CHANDRA observation than in any of the ASCA spectra. The CHANDRA observation also provides the first high-time resolution lightcurve of the uncontaminated stellar X-ray emission from 77 Carinae and shows that there is no significant, coherent variability during the CHANDRA observation. The 77 Carinae CHANDRA grating spectrum is unlike recently published X-ray grating spectra of single massive stars in significant ways and is generally consistent with colliding wind emission in a massive binary.

  2. The Soft X-ray Spectrum of the High Mass X-Ray Binary V0332+53 in Quiescence

    Science.gov (United States)

    Elshamouty, Khaled G.; Heinke, Craig O.; Chouinard, Rhys

    2016-08-01

    The behaviour of neutron stars in high mass X-ray binaries (HMXBs) during periods of low mass transfer is of great interest. Indications of spectral softening in systems at low mass transfer rates suggest that some HMXBs are undergoing fundamental changes in their accretion regime, but the nature of the quiescent X-ray emission is not clear. We performed a 39 ks XMM-Newton observation of the transient HMXB V0332+53, finding it at a very low X-ray luminosity (Lx ˜ 4 × 1032 erg s-1). A power-law spectral fit requires an unusually soft spectral index (4.4^{+0.9}_{-0.6}), while a magnetized neutron star atmosphere model, with temperature LogTeff 6.7±0.2 K and inferred emitting radius of ˜0.2 - 0.3 km, gives a good fit. We suggest that the quiescent X-ray emission from V0332+53 is mainly from a hot spot on the surface of the neutron star. No conclusions on the presence of pulsations could be drawn due to the low count rate. Due to the high absorption column, thermal emission from the rest of the neutron star could be only weakly constrained, to LogTeff <6.14^{+0.05}_{-6.14} K, or <3 × 1033 erg s-1.

  3. X-Ray Ccds for Space Applications: Calibration, Radiation Hardness, and Use for Measuring the Spectrum of the Cosmic X-Ray Background

    Science.gov (United States)

    Gendreau, Keith Charles

    1995-01-01

    This thesis has two distinct components. One concerns the physics of the high energy resolution X-ray charge coupled devices (CCD) detectors used to measure the cosmic X-ray background (XRB) spectrum. The other involves the measurements and analysis of the XRB spectrum and instrumental background with these detectors on board the advanced satellite for cosmology and astrophysics (ASCA). The XRB has a soft component and a hard component divided at ~2 keV. The hard component is extremely isotropic, suggesting a cosmological origin. The soft component is extremely anisotropic. A galactic component most likely dominates the soft band with X-ray line emission due to a hot plasma surrounding the solar system. ASCA is one of the first of a class of missions designed to overlap the hard and soft X-ray bands. The X-ray CCD's energy resolution allows us to spectrally separate the galactic and cosmological components. Also, the resolution offers the ability to test several specific cosmological models which would make up the XRB. I have concentrated on models for the XRB origin which include active galactic nuclei (AGN) as principal components. I use ASCA data to put spectral constraints on the AGN synthesis model for the XRB. The instrumental portion of this thesis concerns the development and calibration of the X-ray CCDs. I designed, built and operated an X-ray calibration facility for these detectors. It makes use of a reflection grating spectrometer to measure absolute detection efficiency, characteristic absorption edge strengths, and spectral redistribution in the CCD response function. Part of my thesis research includes a study of radiation damage mechanisms in CCDs. This work revealed radiation damage-induced degradation in the spectral response to X-rays. It also uncovered systematic effects which affect both data analysis and CCD design. I have developed a model involving trap energy levels in the CCD band gap structure. These traps reduce the efficiency in which

  4. Suzaku observations of the hard X-ray spectrum of Vela Jr. (SNR RX J0852.0-4622)

    Science.gov (United States)

    Takeda, Sawako; Bamba, Aya; Terada, Yukikatsu; Tashiro, Makoto S.; Katsuda, Satoru; Yamazaki, Ryo; Ohira, Yutaka; Iwakiri, Wataru

    2016-06-01

    We report the results of Suzaku observations of the young supernova remnant, Vela Jr. (RX J0852.0-4622), which is known to emit synchrotron X-rays, as well as TeV gamma-rays. Utilizing 39 Suzaku mapping observation data from Vela Jr., a significant hard X-ray emission is detected with the hard X-ray detector (HXD) from the northwest TeV-emitting region. The X-ray spectrum is reproduced well by a single power-law model with a photon index of 3.15^{+1.18}_{-1.14} in the 12-22 keV band. Compiling this hard X-ray spectrum with the soft X-ray spectrum simultaneously observed with the X-ray imaging spectrometer (XIS) onboard Suzaku, we find that the wide-band X-ray spectrum in the 2-22 keV band is reproduced with a single power-law or concave broken power-law model, which are statistically consistent with each other. Whichever of the two models, single or broken power-law, is appropriate, clearly the spectrum has no roll-off structure. Applying this result to the method introduced in Yamazaki et al. (2014, Res. Astron. Astrophys., 14, 165), we find that a one-zone synchrotron model with electron spectrum having a power-law plus exponential cut-off may not be applicable to Vela Jr.

  5. X-ray variability of 104 active galactic nuclei. XMM-Newton power-spectrum density profiles

    CERN Document Server

    Gonzalez-Martin, O

    2012-01-01

    AGN, powered by accretion onto SMBHs, are thought to be scaled up versions of Galactic black hole X-ray binaries (BH-XRBs). In the past few years evidence of such correspondence include similarities in the broadband shape of the X-ray variability power spectra, with characteristic bend times-scales scaling with mass. We have performed a uniform analysis of the power spectrum densities (PSDs) of 104 nearby (z<0.4) AGN using 209 XMM-Newton/pn observations. The PSDs have been estimated in three energy bands: 0.2-10, 0.2-2, and 2-10 keV. The sample comprises 61 Type-1 AGN, 21 Type-2 AGN, 15 NLSy1, and 7 BLLACS. We have fitted each PSD to two models: (1) a single power-law model and (2) a bending power-law model. Among the entire sample, 72% show significant variability in at least one of the three bands tested. A high percentage of low-luminosity AGN do not show any significant variability. The PSD of the majority of the variable AGN was well described by a simple power-law with a mean index of 2. In 15 source...

  6. Effects of synchrotron radiation spectrum energy on polymethyl methacrylate photosensitivity to deep x-ray lithography

    CERN Document Server

    Mekaru, H; Hattori, T

    2003-01-01

    Since X-ray lithography requires a high photon flux to achieve deep resist exposure, a synchrotron radiation beam, which is not monochromatized, is generally used as a light source. If the synchrotron radiation beam is monochromatized, photon flux will decrease rapidly. Because of this reason, the wavelength dependence of the resist sensitivity has not been investigated for deep X-ray lithography. Measuring the spectrum of a white beam with a Si solid-state detector (SSD) is difficult because a white beam has a high intensity and an SSD has a high sensitivity. We were able to measure the spectrum and the photocurrent of a white beam from a beam line used for deep X-ray lithography by keeping the ring current below 0.05 mA. We evaluated the characteristics of the output beam based on the measured spectrum and photocurrent, and used them to investigate the relationship between the total exposure energy and the dose-processing depth with polymethyl methacrylate (PMMA). We found that it is possible to guess the p...

  7. The X-Ray Spectrum and Global Structure of the Stellar Wind in Vela X-1

    CERN Document Server

    Sako, M; Kahn, S M; Paerels, F B S; Sako, Masao; Liedahl, Duane A.; Kahn, Steven M.; Paerels, Frits

    1999-01-01

    We present a quantitative analysis of the X-ray spectrum of the eclipsing high mass X-ray binary Vela X-1 (4U 0900-40) using archival data from ASCA. The observation covers a time interval centered on eclipse of the X-ray pulsar by the companion. The spectrum exhibits two distinct sets of discrete features: (1) recombination lines and radiative recombination continua from mostly H- and He-like species produced by photoionization in an extended stellar wind; and (2) fluorescent K-shell lines associated with near-neutral species also present in the circumsource medium. Using a detailed spectral model that explicitly accounts for the recombination cascade kinetics for each of the constituent charge states, we are able to obtain a statistically acceptable (chi_r^2=0.88) fit to the observed spectrum and to derive emission measures associated with the individual K-shell ions of several elements. We find a best-fit mass loss rate of ~2.7 x 10^-7 M-solar/yr, which is approximately a factor of 10 lower than previous e...

  8. The Soft X-ray Spectrum of the High Mass X-Ray Binary V0332+53 in Quiescence

    CERN Document Server

    Elshamouty, K; Chouinard, R

    2016-01-01

    The propeller effect should cut off accretion in fast-spinning neutron star high mass X-ray binaries (HMXBs) at low mass transfer rates. However, accretion continues in some HMXBs at $L_{x} < 10^{34}$ erg s$^{-1}$, as evidenced by continuing pulsations. Indications of spectral softening in systems in the propeller regime suggest that some HMXBs are undergoing fundamental changes in their accretion regime. A 39 ks \\textit{XMM-Newton} observation of the transient HMXB V0332+53 found it at a very low X-ray luminosity ($L_{x} \\sim 4\\times 10^{32}$ erg s${^{-1}}$). A power-law spectral fit requires an unusually soft spectral index ($4.4^{+0.9}_{-0.6}$), while a magnetized neutron star atmosphere model, with temperature \\lt\\ 6.7$\\pm 0.2$ K and inferred emitting radius of $\\sim0.2-0.3$ km, gives a good fit. We suggest that the quiescent X-ray emission from V0332+53 is mainly from a hot spot on the surface of the neutron star. We could not detect pulsations from V0332+53, due to the low count rate. Due to the high...

  9. [Application of the racial algorithm in energy dispersive X-ray fluorescence overlapped spectrum analysis].

    Science.gov (United States)

    Zeng, Guo-Qiang; Luo, Yao-Yao; Ge, Liang-Quan; Zhang, Qing-Xian; Gu, Yi; Cheng, Feng

    2014-02-01

    In the energy dispersive X-ray fluorescence spectrum analysis, scintillation detector such as NaI (Tl) detector usually has a low energy resolution at around 8%. The low energy resolution causes problems in spectral data analysis especially in the high background and low counts condition, it is very limited to strip the overlapped spectrum, and the more overlapping the peaks are, the more difficult to peel the peaks, and the qualitative and quantitative analysis can't be carried out because we can't recognize the peak address and peak area. Based on genetic algorithm and immune algorithm, we build a new racial algorithm which uses the Euclidean distance as the judgment of evolution, the maximum relative error as the iterative criterion to be put into overlapped spectrum analysis, then we use the Gaussian function to simulate different overlapping degrees of the spectrum, and the racial algorithm is used in overlapped peak separation and full spectrum simulation, the peak address deviation is in +/- 3 channels, the peak area deviation is no more than 5%, and it is proven that this method has a good effect in energy dispersive X-ray fluorescence overlapped spectrum analysis.

  10. 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...

  11. Broadband Ultrahigh-Resolution Spectroscopy of Particle-Induced X Rays: Extending the Limits of Nondestructive Analysis

    Science.gov (United States)

    Palosaari, M. R. J.; Käyhkö, M.; Kinnunen, K. M.; Laitinen, M.; Julin, J.; Malm, J.; Sajavaara, T.; Doriese, W. B.; Fowler, J.; Reintsema, C.; Swetz, D.; Schmidt, D.; Ullom, J. N.; Maasilta, I. J.

    2016-08-01

    Nondestructive analysis (NDA) based on x-ray emission is widely used, for example, in the semiconductor and concrete industries. Here, we demonstrate significant quantitative and qualitative improvements in broadband x-ray NDA by combining particle-induced emission with detection based on superconducting microcalorimeter arrays. We show that the technique offers great promise in the elemental analysis of thin-film and bulk samples, especially in the difficult cases where tens of different elements with nearly overlapping emission lines have to be identified down to trace concentrations. We demonstrate the efficiency and resolving capabilities by spectroscopy of several complex multielement samples in the energy range 1-10 keV, some of which have a trace amount of impurities not detectable with standard silicon drift detectors. The ability to distinguish the chemical environment of an element is also demonstrated by measuring the intensity differences and chemical shifts of the characteristics x-ray peaks of titanium compounds. In particular, we report measurements of the K α /K β intensity ratio of thin films of TiN and measurements of Ti K α satellite peak intensities in various Ti thin-film compounds. We also assess the detection limits of the technique, comment on detection limits possible in the future, and discuss possible applications.

  12. Hard X-Ray Spectrum from West Lobe of Radio Galaxy Fornax A Observed with Suzaku

    CERN Document Server

    Tashiro, Makoto S; Seta, Hiromi; Matsuta, Keiko; Yaji, Yuichi

    2009-01-01

    An observation of the West lobe of radio galaxy Fornax A (NGC 1316) with Suzaku is reported. Since Feigelson et al. (1995) and Kaneda et al. (1995) discovered the cosmic microwave background boosted inverse-Comptonized (IC) X-rays from the radio lobe, the magnetic field and electron energy density in the lobes have been estimated under the assumption that a single component of the relativistic electrons generates both the IC X-rays and the synchrotron radio emission. However, electrons generating the observed IC X-rays in the 1 -- 10 keV band do not possess sufficient energy to radiate the observed synchrotron radio emission under the estimated magnetic field of a few micro-G. On the basis of observations made with Suzaku, we show in the present paper that a 0.7 -- 20 keV spectrum is well described by a single power-law model with an energy index of 0.68 and a flux density of 0.12+/-0.01 nJy at 1 keV from the West lobe. The derived multiwavelength spectrum strongly suggests that a single electron energy distr...

  13. Hard X-ray Spectrum of Mkn 421 during the Active Phase

    Indian Academy of Sciences (India)

    R. K. Manchanda

    2001-06-01

    Spectral measurement of Mkn 421 were made in the hard X-ray energy band of 20–200 keV using a high sensitivity, large area scintillation counter telescope on November 21, 2000 and these coincided with the onset of an active X-ray phase as seen in the ASM counting rates on board RXTE. The observed spectrum can not be fitted to a single power law similar to the PDS data of BeppoSAX. The data can be fitted both by a two component power-law function or a combination of an exponential function with a power law component at the high energies above 80 keV. We identify these components with those arising from the synchrotron self compton and the high energy power-law tail arising from the upgrading of the thermal photons due to multiple Compton scattering a la Cyg X-1. A comparison with the earlier data clearly suggests a spectral variability in the hard X-ray spectrum of the source. We propose a continuously flaring geometry for the source as the underlying mechanism for energy release.

  14. Segmentation-free x-ray energy spectrum estimation for computed tomography

    CERN Document Server

    Zhao, Wei; Niu, Tianye

    2016-01-01

    X-ray energy spectrum plays an essential role in imaging and related tasks. Due to the high photon flux of clinical CT scanners, most of the spectrum estimation methods are indirect and are usually suffered from various limitations. The recently proposed indirect transmission measurement-based method requires at least the segmentation of one material, which is insufficient for CT images of highly noisy and with artifacts. To combat for the bottleneck of spectrum estimation using segmented CT images, in this study, we develop a segmentation-free indirect transmission measurement based energy spectrum estimation method using dual-energy material decomposition. The general principle of the method is to compare polychromatic forward projection with raw projection to calibrate a set of unknown weights which are used to express the unknown spectrum together with a set of model spectra. After applying dual-energy material decomposition using high- and low-energy raw projection data, polychromatic forward projection ...

  15. A New Observation of the Quiet Sun Soft X-ray (0.5-5 keV) Spectrum

    Science.gov (United States)

    Caspi, A.; Woods, T. N.; Stone, J.

    2012-12-01

    The solar corona is the brightest source of X-rays in the solar system, and the X-ray emission is highly variable with solar activity. While this is particularly true during solar flares, when emission can be enhanced by many orders of magnitude up to gamma-ray energies, even the so-called "quiet Sun" is bright in soft X-rays (SXRs), as the ~1-2 MK ambient plasma of the corona emits significant thermal bremsstrahlung up to ~5 keV. However, the actual solar SXR (0.5-5 keV) spectrum is not well known, particularly during quiet periods, as, with few exceptions, this energy range has not been systematically studied in many years. Previous observations include ultra-high-resolution but very narrow-band spectra from crystral spectrometers (e.g. Yohkoh/BCS), or integrated broadband irradiances from photometers (e.g. GOES/XRS, TIMED/XPS, etc.) that lack detailed spectral information. In recent years, broadband measurements with fair energy resolution (~0.5-0.7 keV FWHM) were made by SphinX on CORONAS-Photon and XRS on MESSENGER, although they did not extend below ~1 keV. We present observations of the quiet Sun SXR emission obtained using a new SXR spectrometer flown on the third SDO/EVE underflight calibration rocket (NASA 36.286). The commercial off-the-shelf Amptek X123 silicon drift detector, with an 8-micron Be window and custom aperture, measured the solar SXR emission from ~0.5 to >10 keV with ~0.15 keV FWHM resolution (though, due to hardware limitations, with only ~0.12 keV binning) and 2-sec cadence over ~5 minutes on 23 June 2012. Despite the rising solar cycle, activity on 23 June 2012 was abnormally low, with no visible active regions and GOES XRS emission near 2010 levels; we measured no solar counts above ~4 keV during the observation period. We compare our X123 measurements with spectra and broadband irradiances from other instruments, including the SphinX observations during the deep solar minimum of 2009, and with upper limits of >3 keV quiet Sun emission

  16. The X-ray spectrum of delta Orionis observed by LETGS aboard Chandra

    CERN Document Server

    Raassen, A J J

    2013-01-01

    We analyze the high-resolution X-ray spectrum of the supergiant O-star delta Orionis (O9.5II) with line ratios of He-like ions and a thermal plasma model, and we examine its variability. The O-supergiant delta Ori was observed in the wavelength range 5-175 Angstrom by the X-ray detector HRC-S in combination with the grating LETG aboard Chandra. We studied the He-like ions in combination with the UV-radiation field to determine local plasma temperatures and to establish the distance of the X-ray emitting ions to the stellar surface. We measured individual lines by means of Gaussian profiles, folded through the response matrix, to obtain wavelengths, line fluxes, half widths at half maximum (HWHM) and line shifts to characterize the plasma. We consider multitemperature models in collisional ionization equilibrium (CIE) to determine temperatures, emission measures, and abundances. Analysis of the He-like triplets extended to N VI and C V implies ionization stratification with the hottest plasma to be found withi...

  17. A variable absorption feature in the X-ray spectrum of a magnetar.

    Science.gov (United States)

    Tiengo, Andrea; Esposito, Paolo; Mereghetti, Sandro; Turolla, Roberto; Nobili, Luciano; Gastaldello, Fabio; Götz, Diego; Israel, Gian Luca; Rea, Nanda; Stella, Luigi; Zane, Silvia; Bignami, Giovanni F

    2013-08-15

    Soft-γ-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are slowly rotating, isolated neutron stars that sporadically undergo episodes of long-term flux enhancement (outbursts) generally accompanied by the emission of short bursts of hard X-rays. This behaviour can be understood in the magnetar model, according to which these sources are mainly powered by their own magnetic energy. This is supported by the fact that the magnetic fields inferred from several observed properties of SGRs and AXPs are greater than-or at the high end of the range of-those of radio pulsars. In the peculiar case of SGR 0418+5729, a weak dipole magnetic moment is derived from its timing parameters, whereas a strong field has been proposed to reside in the stellar interior and in multipole components on the surface. Here we show that the X-ray spectrum of SGR 0418+5729 has an absorption line, the properties of which depend strongly on the star's rotational phase. This line is interpreted as a proton cyclotron feature and its energy implies a magnetic field ranging from 2 × 10(14) gauss to more than 10(15) gauss. PMID:23955229

  18. Spectrum unfolding in X-ray spectrometry using the maximum entropy method

    International Nuclear Information System (INIS)

    The solution of the unfolding problem is an ever-present issue in X-ray spectrometry. The maximum entropy technique solves this problem by taking advantage of some known a priori physical information and by ensuring an outcome with only positive values. This method is implemented in MAXED (MAXimum Entropy Deconvolution), a software code contained in the package UMG (Unfolding with MAXED and GRAVEL) developed at PTB and distributed by NEA Data Bank. This package contains also the code GRAVEL (used to estimate the precision of the solution). This article introduces the new code UMESTRAT (Unfolding Maximum Entropy STRATegy) which applies a semi-automatic strategy to solve the unfolding problem by using a suitable combination of MAXED and GRAVEL for applications in X-ray spectrometry. Some examples of the use of UMESTRAT are shown, demonstrating its capability to remove detector artifacts from the measured spectrum consistently with the model used for the detector response function (DRF). - Highlights: ► A new strategy to solve the unfolding problem in X-ray spectrometry is presented. ► The presented strategy uses a suitable combination of the codes MAXED and GRAVEL. ► The applied strategy provides additional information on the Detector Response Function. ► The code UMESTRAT is developed to apply this new strategy in a semi-automatic mode

  19. A variable absorption feature in the X-ray spectrum of a magnetar

    CERN Document Server

    Tiengo, Andrea; Mereghetti, Sandro; Turolla, Roberto; Nobili, Luciano; Gastaldello, Fabio; Gotz, Diego; Israel, GianLuca; Rea, Nanda; Stella, Luigi; Zane, Silvia; Bignami, Giovanni F

    2013-01-01

    Soft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are slowly rotating, isolated neutron stars that sporadically undergo episodes of long-term flux enhancement (outbursts) generally accompanied by the emission of short bursts of hard X-rays. This behaviour can be understood in the magnetar model, according to which these sources are mainly powered by their own magnetic energy. This is supported by the fact that the magnetic fields inferred from several observed properties of AXPs and SGRs are greater than - or at the high end of the range of - those of radio pulsars. In the peculiar case of SGR 0418+5729, a weak dipole magnetic moment is derived from its timing parameters, whereas a strong field has been proposed to reside in the stellar interior and in multipole components on the surface. Here we show that the X-ray spectrum of SGR 0418+5729 has an absorption line, the properties of which depend strongly on the star's rotational phase. This line is interpreted as a proton cyclotron feature an...

  20. A variable absorption feature in the X-ray spectrum of a magnetar.

    Science.gov (United States)

    Tiengo, Andrea; Esposito, Paolo; Mereghetti, Sandro; Turolla, Roberto; Nobili, Luciano; Gastaldello, Fabio; Götz, Diego; Israel, Gian Luca; Rea, Nanda; Stella, Luigi; Zane, Silvia; Bignami, Giovanni F

    2013-08-15

    Soft-γ-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are slowly rotating, isolated neutron stars that sporadically undergo episodes of long-term flux enhancement (outbursts) generally accompanied by the emission of short bursts of hard X-rays. This behaviour can be understood in the magnetar model, according to which these sources are mainly powered by their own magnetic energy. This is supported by the fact that the magnetic fields inferred from several observed properties of SGRs and AXPs are greater than-or at the high end of the range of-those of radio pulsars. In the peculiar case of SGR 0418+5729, a weak dipole magnetic moment is derived from its timing parameters, whereas a strong field has been proposed to reside in the stellar interior and in multipole components on the surface. Here we show that the X-ray spectrum of SGR 0418+5729 has an absorption line, the properties of which depend strongly on the star's rotational phase. This line is interpreted as a proton cyclotron feature and its energy implies a magnetic field ranging from 2 × 10(14) gauss to more than 10(15) gauss.

  1. Mapping the Broad-band Spectrum of a New Candidate Intermediate Mass Black Hole

    Science.gov (United States)

    Farrell, Sean

    2014-10-01

    We request joint XMM-Newton & HST observations of a new intermediate mass black hole candidate in the galaxy LEDA 87326 to map the broad-band spectral energy distribution from X-ray to near-IR. Previous observations with the XMM-Newton EPIC and OM cameras detected an X-ray source with an observed 0.2-10 keV luminosity of 6E41 erg/s, with the X-ray spectrum dominated by a hard power law and the UV/optical data consistent with thermal emission from a cool (~0.08 keV) accretion disc. The high X-ray luminosity and low disc temperature imply a black hole mass > 4000 Msun. By observing this source simultaneously with XMM-Newton and the HST we will confirm that the observed optical emission is from an accretion disc and determine whether any reprocessing in the outer disc is present.

  2. What is the correct Fe L{sub 23} X-ray absorption spectrum of magnetite?

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiaohui; Kalirai, Samanbir S. [Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON L8S 4M1 (Canada); Hitchcock, Adam P., E-mail: aph@mcmaster.ca [Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON L8S 4M1 (Canada); Bazylinski, Dennis A. [School of Life Sciences, University of Nevada at Las Vegas, Las Vegas, NV 89154-4004 (United States)

    2015-02-15

    Highlights: • Fe L{sub 3} X-ray absorption spectra of biological (MV-1 magnetotactic bacteria) and abiotic (Sigma–Aldrich) nano-magnetite are reported. • An inconsistency in the literature for this spectrum is documented. • Powder diffraction shows the abiotic sample is partly oxidized, toward maghemite. • H{sub 2} thermal reduction converts the Fe L{sub 3} spectrum of the abiotic sample to that of the biotic. • Strong oxidation (air, 600 °C) is needed to convert the spectrum of the biotic magnetite to that of maghemite; magnetosome chains are protected by an air-impervious membrane. - Abstract: Various groups have reported Fe L{sub 23} X-ray absorption spectra (XAS) of magnetite (Fe{sub 3}O{sub 4}), each claiming to be that of magnetite, but which contradict each other. Here we report an XAS study of two kinds of magnetite: one is biogenic magnetite nanocrystals extracted from the magnetotactic bacterium Magnetovibrio blakemorei strain MV-1; the other is synthetic, abiogenically produced nano-magnetite. We see significantly different XAS spectra of these two materials. Only when the abiogenic magnetite was reduced under H{sub 2} did it give the same spectrum as the biogenic sample. Extensive heating of the biogenic magnetite in air produced spectra similar to that of the abiogenic magnetite. These two spectra are typical of the range of published Fe L{sub 23} spectra of magnetite. X-ray diffraction confirmed that the biogenic material is stoichiometric Fe{sub 3}O{sub 4}, and showed that the as-received or partly reduced abiogenic material is a non-stoichiometric oxide, intermediate between magnetite and maghemite (γ-Fe{sub 2}O{sub 3}). When the membrane which surrounds magnetosome chains was intact, the biotic magnetite single crystals were surprisingly resistant to oxidation. This study clarifies a significant confusion existing in the literature as to the correct Fe L{sub 23} X-ray absorption spectra of magnetite and maghemite.

  3. The X-ray Spectrum of Soft Gamma Repeater 1806-20

    OpenAIRE

    Fenimore, E. E.; Laros, J. G.; Ulmer, A.

    1994-01-01

    Soft Gamma Repeaters (SGRs) are a class of rare, high-energy galactic transients that have episodes of short (~0.1 sec), soft (~30 keV), intense (~100 Crab), gamma-ray bursts. We report an analysis of the x-ray emission from 95 SGR1806-20 events observed by the International Cometary Explorer. The spectral shape remains remarkably constant for bursts that differ in intensity by a range of 50. Below 15 keV the number spectrum falls off rapidly such that we can estimate the total intensity of t...

  4. A Deep Chandra X-ray Spectrum of the Accreting Young Star TW Hydrae

    OpenAIRE

    Brickhouse, N. S.; Cranmer, S. R.; Dupree, A. K.; Luna, G. J. M.; Wolk, S.

    2010-01-01

    We present X-ray spectral analysis of the accreting young star TW Hydrae from a 489 ks observation using the Chandra High Energy Transmission Grating. The spectrum provides a rich set of diagnostics for electron temperature T_e, electron density N_e, hydrogen column density N_H, relative elemental abundances and velocities and reveals its source in 3 distinct regions of the stellar atmosphere: the stellar corona, the accretion shock, and a very large extended volume of warm postshock plasma. ...

  5. A new, high-precision measurement of the X-ray Cu K α spectrum

    Science.gov (United States)

    Mendenhall, Marcus H.; Cline, James P.; Henins, Albert; Hudson, Lawrence T.; Szabo, Csilla I.; Windover, Donald

    2016-03-01

    One of the primary measurement issues addressed with NIST Standard Reference Materials (SRMs) for powder diffraction is that of line position. SRMs for this purpose are certified with respect to lattice parameter, traceable to the SI through precise measurement of the emission spectrum of the X-ray source. Therefore, accurate characterization of the emission spectrum is critical to a minimization of the error bounds on the certified parameters. The presently accepted sources for the SI traceable characterization of the Cu K α emission spectrum are those of Härtwig, Hölzer et al., published in the 1990s. The structure of the X-ray emission lines of the Cu K α complex has been remeasured on a newly commissioned double-crystal instrument, with six-bounce Si (440) optics, in a manner directly traceable to the SI definition of the meter. In this measurement, the entire region from 8020 eV to 8100 eV has been covered with a highly precise angular scale and well-defined system efficiency, providing accurate wavelengths and relative intensities. This measurement is in modest disagreement with reference values for the wavelength of the Kα1 line, and strong disagreement for the wavelength of the Kα2 line.

  6. Constraining high-redshift X-ray sources with next generation 21-cm power spectrum measurements

    Science.gov (United States)

    Ewall-Wice, Aaron; Hewitt, Jacqueline; Mesinger, Andrei; Dillon, Joshua S.; Liu, Adrian; Pober, Jonathan

    2016-05-01

    We use the Fisher matrix formalism and seminumerical simulations to derive quantitative predictions of the constraints that power spectrum measurements on next-generation interferometers, such as the Hydrogen Epoch of Reionization Array (HERA) and the Square Kilometre Array (SKA), will place on the characteristics of the X-ray sources that heated the high-redshift intergalactic medium. Incorporating observations between z = 5 and 25, we find that the proposed 331 element HERA and SKA phase 1 will be capable of placing ≲ 10 per cent constraints on the spectral properties of these first X-ray sources, even if one is unable to perform measurements within the foreground contaminated `wedge' or the FM band. When accounting for the enhancement in power spectrum amplitude from spin temperature fluctuations, we find that the observable signatures of reionization extend well beyond the peak in the power spectrum usually associated with it. We also find that lower redshift degeneracies between the signatures of heating and reionization physics lead to errors on reionization parameters that are significantly greater than previously predicted. Observations over the heating epoch are able to break these degeneracies and improve our constraints considerably. For these two reasons, 21-cm observations during the heating epoch significantly enhance our understanding of reionization as well.

  7. A high resolution spectrum of the diffuse soft X-ray background

    Science.gov (United States)

    Crowder, S. Gwynne

    Galactic contributions to the diffuse X-ray background were believed to largely come from thermal emission of hot gas and models of the Galactic neighborhood within ˜ 100 pc reflected this belief. However, recent observations led to the realization that emission from charge exchange within the Solar System might produce comparable intensities to that of thermal emission. A high resolution spectrum of the diffuse X-ray background from 0.1 to 1 keV was obtained for a ˜ 1 sr region of the sky centered at l = 90°, b = +60° in May 2008 using a 36 pixel array of microcalorimeters flown on a sounding rocket. With an energy resolution of 11 eV FWHM below 1 keV, the spectrum can be used to separate charge exchange contributions originating within the heliosphere from thermal emission of hot gas in the interstellar medium. The X-ray sensitivity below 1 keV was reduced about a factor of four by contamination that occurred early in the flight, limiting the significance of the results. The observed ratio of helium-like O VII forbidden plus intercombination to resonance lines is 1.2 +/- 1.2 at 90% confidence. This indicates that at least 67% of the emission is thermal. On the other hand, the observed ratio of C VI Lygamma to Lyalpha is 0.3+0.3-0.2 , requiring at least a 33% contribution from charge exchange. In addition to these astrophysical results, I present experimental improvements from the addition of a gold coating to the detector array substrate which greatly reduces extraneous signals and from the use of silicon support meshes which improves blocking filter robustness. I also detail a new optimal filtering analysis technique that preserves spectral resolution and live time in the presence of pulse overlap.

  8. Spectral Interferences Manganese (Mn) - Europium (Eu) Lines in X-Ray Fluorescence Spectrometry Spectrum

    Science.gov (United States)

    Tanc, Beril; Kaya, Mustafa; Gumus, Lokman; Kumral, Mustafa

    2016-04-01

    X-ray fluorescence (XRF) spectrometry is widely used for quantitative and semi quantitative analysis of many major, minor and trace elements in geological samples. Some advantages of the XRF method are; non-destructive sample preparation, applicability for powder, solid, paste and liquid samples and simple spectrum that are independent from chemical state. On the other hand, there are some disadvantages of the XRF methods such as poor sensitivity for low atomic number elements, matrix effect (physical matrix effects, such as fine versus course grain materials, may impact XRF performance) and interference effect (the spectral lines of elements may overlap distorting results for one or more elements). Especially, spectral interferences are very significant factors for accurate results. In this study, semi-quantitative analyzed manganese (II) oxide (MnO, 99.99%) was examined. Samples were pelleted and analyzed with XRF spectrometry (Bruker S8 Tiger). Unexpected peaks were obtained at the side of the major Mn peaks. Although sample does not contain Eu element, in results 0,3% Eu2O3 was observed. These result can occur high concentration of MnO and proximity of Mn and Eu lines. It can be eliminated by using correction equation or Mn concentration can confirm with other methods (such as Atomic absorption spectroscopy). Keywords: Spectral Interferences; Manganese (Mn); Europium (Eu); X-Ray Fluorescence Spectrometry Spectrum.

  9. The soft X-ray spectrum of transient pulsars in the Small Magellanic Cloud

    Science.gov (United States)

    La Palombara, N.; Sidoli, L.; Esposito, P.; Pintore, F.; Tiengo, A.; Mereghetti, S.

    2016-06-01

    The Small Magellanic Cloud is characterized by a high number of transient accreting pulsars, which can reach luminosities up to 10^{38} erg s^{-1} during their outbursts. Due to the low Galactic interstellar absorption in the SMC direction, these sources offer a unique opportunity to investigate the soft end of the X-ray spectrum in accreting pulsars. In the last two years we observed with XMM-Newton the large outburst of two of these transient pulsars (RX J0059.2-7138 and SMC X-2). Thanks to the high throughput and spectral resolution of XMM, these observations allowed us to investigate at an unprecedented level of detail their spectral and timing properties at soft X-ray energies. We found that both sources show a pulsed emission also at low energies, and that they are characterized by a thermal component which dominates the source spectrum below 0.5 keV; moreover, we discovered several emission and absorption features, which are very likely produced by photoionization of plasma located above the inner regions of the accretion disc.

  10. Investigating Dueling Scenarios in NGC 7582 with Broadband X-ray Spectroscopy

    Science.gov (United States)

    Rivers, E.

    2015-09-01

    NGC 7582 is a well-studied X-ray bright Seyfert 2 with moderately heavy (NH = 10^{23} - 10^{24} cm^{-2}), highly variable absorption and unusually strong reflection spectral features. The spectral shape changed around the year 2000, dropping in observed flux and becoming much more highly absorbed. Two scenarios have been put forth to explain this spectral change: 1) the source "shut off" around this time, decreasing in intrinsic luminosity, with a delayed decrease in reflection features due to the light crossing time of the Compton-thick material or 2) the source is a "hidden nucleus" which has recently become more heavily obscured, with only a portion of the power law continuum leaking through. NuSTAR observed NGC 7582 twice in 2012 two weeks apart in order to quantify the reflection using high-quality data above 10 keV. We analyze both NuSTAR observations placing them in the context of historical X-ray, infrared and optical observations, including re-analysis of RXTE data from 2003-2005. We find that the most plausible scenario is that NGC 7582 has a hidden nucleus which has recently become more heavily absorbed by a patchy torus with a covering fraction of 80-90% and a column density of 3.6 x 10^{24} cm^{-2}. We find the need for an additional highly variable full-covering absorber with NH= 4-6 x 10^{23} cm^{-2}, possibly associated with a hidden broad line region or a dust lane in the host galaxy.

  11. Impulsive solar X-ray bursts. 4: Polarization, directivity and spectrum of the reflected and total bremsstrahlung radiation from a beam of electrons directed toward the photosphere

    Science.gov (United States)

    Langer, S. H.; Petrosian, V.

    1976-01-01

    A Monte Carlo method is described for evaluation of the spectrum, directivity and polarization of X-rays diffusely reflected from stellar photospheres. the accuracy of the technique is evaluated through comparison with analytic results. Using the characteristics of the incident X-rays of the model for solar X-ray flares, the spectrum, directivity and polarization of the reflected and the total X-ray fluxes are evaluated. The results are compared with observations.

  12. 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.

  13. Effects of X-rays spectrum on the dose; Efectos del espectro de rayos X sobre la dosis

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez I, J. L.; Hernandez A, P. L.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Rivera M, T., E-mail: johann_greenday@hotmail.com [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria No. 694, 11500 Mexico D. F. (Mexico)

    2015-10-15

    The X-ray equipment for diagnosis comes in different sizes and shapes depending on the scan type to perform. The X-ray spectrum is the energy distribution of the beam photons and consists of a continuous spectrum of photons braking and discrete spectrum due to the characteristic photons. The knowledge of the X-rays spectrum is important to understand like they affect the voltage changes (k Vp), current (m A), time (s) and the type of filter in the interaction mechanisms between X-rays and patient's body, the image receptor or other material that gets in the beam. Across the spectrum can be estimated the absorbed dose in any point of the patient, the quality of the image and the scattered radiation (which is related to the dose received by the equipment operator). The Monte Carlo method was used by MCNP5 code to calculate the spectrum of X-rays that occurs when a monoenergetic electron beam of 250 keV interact with targets of Mo, Rh and W. The spectra were calculated with and without filter, and the values of ambient dose equivalent were estimated, as well as the air kerma. (Author)

  14. Improving x-ray fluorescence signal for benchtop polychromatic cone-beam x-ray fluorescence computed tomography by incident x-ray spectrum optimization: A Monte Carlo study

    Energy Technology Data Exchange (ETDEWEB)

    Manohar, Nivedh [Nuclear/Radiological Engineering and Medical Physics Programs, Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Jones, Bernard L. [Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado 80045 (United States); Cho, Sang Hyun, E-mail: scho@mdanderson.org [Department of Radiation Physics and Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States)

    2014-10-15

    Purpose: To develop an accurate and comprehensive Monte Carlo (MC) model of an experimental benchtop polychromatic cone-beam x-ray fluorescence computed tomography (XFCT) setup and apply this MC model to optimize incident x-ray spectrum for improving production/detection of x-ray fluorescence photons from gold nanoparticles (GNPs). Methods: A detailed MC model, based on an experimental XFCT system, was created using the Monte Carlo N-Particle (MCNP) transport code. The model was validated by comparing MC results including x-ray fluorescence (XRF) and scatter photon spectra with measured data obtained under identical conditions using 105 kVp cone-beam x-rays filtered by either 1 mm of lead (Pb) or 0.9 mm of tin (Sn). After validation, the model was used to investigate the effects of additional filtration of the incident beam with Pb and Sn. Supplementary incident x-ray spectra, representing heavier filtration (Pb: 2 and 3 mm; Sn: 1, 2, and 3 mm) were computationally generated and used with the model to obtain XRF/scatter spectra. Quasimonochromatic incident x-ray spectra (81, 85, 90, 95, and 100 keV with 10 keV full width at half maximum) were also investigated to determine the ideal energy for distinguishing gold XRF signal from the scatter background. Fluorescence signal-to-dose ratio (FSDR) and fluorescence-normalized scan time (FNST) were used as metrics to assess results. Results: Calculated XRF/scatter spectra for 1-mm Pb and 0.9-mm Sn filters matched (r ≥ 0.996) experimental measurements. Calculated spectra representing additional filtration for both filter materials showed that the spectral hardening improved the FSDR at the expense of requiring a much longer FNST. In general, using Sn instead of Pb, at a given filter thickness, allowed an increase of up to 20% in FSDR, more prominent gold XRF peaks, and up to an order of magnitude decrease in FNST. Simulations using quasimonochromatic spectra suggested that increasing source x-ray energy, in the

  15. Improving x-ray fluorescence signal for benchtop polychromatic cone-beam x-ray fluorescence computed tomography by incident x-ray spectrum optimization: A Monte Carlo study

    International Nuclear Information System (INIS)

    Purpose: To develop an accurate and comprehensive Monte Carlo (MC) model of an experimental benchtop polychromatic cone-beam x-ray fluorescence computed tomography (XFCT) setup and apply this MC model to optimize incident x-ray spectrum for improving production/detection of x-ray fluorescence photons from gold nanoparticles (GNPs). Methods: A detailed MC model, based on an experimental XFCT system, was created using the Monte Carlo N-Particle (MCNP) transport code. The model was validated by comparing MC results including x-ray fluorescence (XRF) and scatter photon spectra with measured data obtained under identical conditions using 105 kVp cone-beam x-rays filtered by either 1 mm of lead (Pb) or 0.9 mm of tin (Sn). After validation, the model was used to investigate the effects of additional filtration of the incident beam with Pb and Sn. Supplementary incident x-ray spectra, representing heavier filtration (Pb: 2 and 3 mm; Sn: 1, 2, and 3 mm) were computationally generated and used with the model to obtain XRF/scatter spectra. Quasimonochromatic incident x-ray spectra (81, 85, 90, 95, and 100 keV with 10 keV full width at half maximum) were also investigated to determine the ideal energy for distinguishing gold XRF signal from the scatter background. Fluorescence signal-to-dose ratio (FSDR) and fluorescence-normalized scan time (FNST) were used as metrics to assess results. Results: Calculated XRF/scatter spectra for 1-mm Pb and 0.9-mm Sn filters matched (r ≥ 0.996) experimental measurements. Calculated spectra representing additional filtration for both filter materials showed that the spectral hardening improved the FSDR at the expense of requiring a much longer FNST. In general, using Sn instead of Pb, at a given filter thickness, allowed an increase of up to 20% in FSDR, more prominent gold XRF peaks, and up to an order of magnitude decrease in FNST. Simulations using quasimonochromatic spectra suggested that increasing source x-ray energy, in the

  16. Determining the Nature of the SS 433 Binary Using an X-ray Spectrum During Eclipse

    CERN Document Server

    Lopez, L A; Canizares, C R; Schulz, N S; Kane, J F; Lopez, Laura A.; Marshall, Herman L.; Canizares, Claude R.; Schulz, Norbert S.; Kane, Julie F.

    2006-01-01

    We test the physical model of the relativistic jets in the galactic X-ray binary SS 433 proposed in our previous paper using additional observations from the Chandra High Energy Transmission Grating Spectrometer. These observations sample two new orbital/precessional phase combinations. In the observation near orbital phase zero, the H- and He-like Fe lines from both receding and approaching jets are comparably strong and unocculted while the He-like Si line of the receding jet is significantly weaker than that of the approaching jet. This condition may imply the cooler parts of the receding jet are eclipsed by the companion. The X-ray spectrum from this observation has broader emission lines than obtained in Paper I that may arise from the divergence of a conical outflow or from Doppler shift variations during the observation. Using recent optical results, along with the length of the unobscured portion of the receding jet assuming adiabatic cooling, we calculate the radius of the companion to be 9.6+/-1.0 R...

  17. X-ray irradiated protoplanetary disk atmospheres I: Predicted emission line spectrum and photoevaporation

    CERN Document Server

    Ercolano, Barbara; Raymond, John C; Clarke, Cathie C

    2008-01-01

    We present MOCASSIN 2D photoionisation and dust radiative transfer models of a prototypical T Tauri disk irradiated by X-rays from the young pre-main sequence star. The calculations demonstrate a layer of hot gas reaching temperatures of ~10^6 K at small radii and ~10^4 K at a distance of 1 AU. The gas temperatures decrease sharply with depth, but appear to be completely decoupled from dust temperatures down to a column depth of ~5*10^21 cm^-2. We predict that several fine-structure and forbidden lines of heavy elements, as well as recombination lines of hydrogen and helium, should be observable with current and future instrumentation, although optical lines may be smothered by the stellar spectrum. Predicted line luminosities are given for the the brightest collisionally excited lines (down to ~10^-8L_sun, and for recombination transitions from several levels of HI and HeI. The mass loss rate due to X-ray photoevaporation estimated from our models is of the order of 10^-8 M_sun yr^-1, implying a dispersal ti...

  18. The soft X-ray absorption spectrum of the allyl free radical.

    Science.gov (United States)

    Alagia, M; Bodo, E; Decleva, P; Falcinelli, S; Ponzi, A; Richter, R; Stranges, S

    2013-01-28

    The first experimental study of the X-ray absorption spectrum (XAS) of the allyl free radical, CH(2)CHCH(2), is reported. A supersonic He seeded beam of hyperthermal allyl radicals was crossed by a high resolution synchrotron radiation (SR) in the focus of a 3D ion momentum imaging time-of-flight (TOF) spectrometer to investigate the soft X-ray absorption and fragmentation processes. The XAS, recorded as Total-Ion-Yield (TIY), is dominated by C1s electron excitations from either the central carbon atom, C(C), or the two terminal carbon atoms, C(T), to the frontier orbitals, the semi-occupied-molecular-orbital (SOMO) and the lowest-unoccupied-molecular-orbital (LUMO). All of the intense features in the XAS could only be assigned with the aid of ab initio spectral simulation at the Multi-Configuration Self-Consistent-Field (MCSCF) level of theory, this level being required because of the multi-reference nature of the core-excited state wavefunctions of the open shell molecule. The ionization energies (IEs) of the singlet and triplet states of the C1s ionized allyl radical (XPS) were also calculated at the MCSCF level. PMID:23232557

  19. X-ray Spectral Variability and Rapid Variability of the Soft X-ray Spectrum Seyfert 1 Galaxies Ark 564 and Ton S180

    CERN Document Server

    Edelson, R; Pounds, K; Vaughan, S; Markowitz, A R; Marshall, H; Dobbie, P D; Warwick, R; Edelson, Rick; Pounds, Ken; Vaughan, Simon; Markowitz, Alex; Marshall, Herman; Dobbie, Paul; Warwick, Robert

    2001-01-01

    The bright, soft X-ray spectrum Seyfert 1 galaxies Ark 564 and Ton S180 were monitored for 35 days and 12 days with ASCA and RXTE (and EUVE for Ton S180). The short time scale (hours-days) variability patterns were very similar across energy bands, with no evidence of lags between any of the energy bands studied. The fractional variability amplitude was almost independent of energy band. It is difficult to simultaneously explain soft Seyferts stronger variability, softer spectra, and weaker energy-dependence of the variability relative to hard Seyferts. The soft and hard band light curves diverged on the longest time scales probed, consistent with the fluctuation power density spectra that showed relatively greater power on long time scales in the softest bands. The simplest explanation is that a relatively hard, rapidly-variable component dominates the total X-ray spectrum and a slowly-variable soft excess is present in the lowest energy channels of ASCA. Although it would be natural to identify the latter w...

  20. Imprints of a high velocity wind on the soft x-ray spectrum of PG 1211+143

    CERN Document Server

    Pounds, Ken; Reeves, James; Vaughan, Simon; Costa, Michele

    2016-01-01

    An extended XMM-Newton observation of the luminous narrow line Seyfert galaxy PG 1211+143 in 2014 has revealed a more complex high velocity wind, with components distinguished in velocity, ionization level, and column density. Here we report soft x-ray emission and absorption features from the ionized outflow, finding counterparts of both high velocity components, v ~ 0.129c and v ~ 0.066c, recently identified in the highly ionized Fe K absorption spectrum. The lower ionization of the co-moving soft x-ray absorbers imply a distribution of higher density clouds embedded in the main outflow, while much higher column densities for the same flow component in the hard x-ray spectra suggest differing sight lines to the continuum x-ray source.

  1. Imprints of a high-velocity wind on the soft X-ray spectrum of PG1211+143

    Science.gov (United States)

    Pounds, K. A.; Lobban, A.; Reeves, J. N.; Vaughan, S.; Costa, M.

    2016-07-01

    An extended XMM-Newton observation of the luminous narrow-line Seyfert galaxy PG1211+143 in 2014 has revealed a more complex high-velocity wind, with components distinguished in velocity, ionization level, and column density. Here we report soft X-ray emission and absorption features from the ionized outflow, finding counterparts of both high-velocity components, v ˜ 0.129c and v ˜ 0.066c, recently identified in the highly ionized Fe K absorption spectrum. The lower ionization of the comoving soft X-ray absorbers imply a distribution of higher density clouds embedded in the main outflow, while much higher column densities for the same flow component in the hard X-ray spectra suggest differing sightlines to the continuum X-ray source.

  2. A Deep Chandra X-Ray Spectrum of the Accreting Young Star TW Hydrae

    Science.gov (United States)

    Brickhouse, N. S.; Cranmer, S. R.; Dupree, A. K.; Luna, G. J. M.; Wolk, S.

    2010-02-01

    We present X-ray spectral analysis of the accreting young star TW Hydrae from a 489 ks observation using the Chandra High Energy Transmission Grating. The spectrum provides a rich set of diagnostics for electron temperature Te , electron density Ne , hydrogen column density NH , relative elemental abundances, and velocities, and reveals its source in three distinct regions of the stellar atmosphere: the stellar corona, the accretion shock, and a very large extended volume of warm postshock plasma. The presence of Mg XII, Si XIII, and Si XIV emission lines in the spectrum requires coronal structures at ~10 MK. Lower temperature lines (e.g., from O VIII, Ne IX, and Mg XI) formed at 2.5 MK appear more consistent with emission from an accretion shock. He-like Ne IX line ratio diagnostics indicate that Te = 2.50 ± 0.25 MK and Ne = 3.0 ± 0.2 × 1012 cm-3 in the shock. These values agree well with standard magnetic accretion models. However, the Chandra observations significantly diverge from current model predictions for the postshock plasma. This gas is expected to cool radiatively, producing O VII as it flows into an increasingly dense stellar atmosphere. Surprisingly, O VII indicates Ne = 5.7+4.4 -1.2 × 1011 cm-3, 5 times lower than Ne in the accretion shock itself and ~7 times lower than the model prediction. We estimate that the postshock region producing O VII has roughly 300 times larger volume and 30 times more emitting mass than the shock itself. Apparently, the shocked plasma heats the surrounding stellar atmosphere to soft X-ray emitting temperatures and supplies this material to nearby large magnetic structures—which may be closed magnetic loops or open magnetic field leading to mass outflow. Our model explains the soft X-ray excess found in many accreting systems as well as the failure to observe high Ne signatures in some stars. Such accretion-fed coronae may be ubiquitous in the atmospheres of accreting young stars.

  3. The average x-ray/$\\gamma$-ray spectrum of radio-quiet Seyfert 1s

    CERN Document Server

    Gondek-Rosinska, D; Johnson, W N; George, I M; McNaron-Brown, K; Magdziarz, P; Smith, D; Gruber, E

    1996-01-01

    We have obtained the average 1--500 keV spectrum of radio-quiet Seyfert 1s using data from EXOSAT, Ginga, HEAO, and GRO/OSSE. The spectral fit to the combined average EXOSAT and OSSE data is fully consistent with that for Ginga and OSSE, confirming results from an earlier Ginga/OSSE sample. The average spectrum is well-fitted by a power-law X-ray continuum with an energy spectral index of \\alpha \\simeq 0.9 moderately absorbed by an ionized medium and with a Compton reflection component. A high-energy cutoff (or a break) in the the power-law component at a few hundred keV or more is required by the data. We also show that the corresponding average spectrum from HEAO A1 and A4 is fully compatible with that obtained from EXOSAT, Ginga and OSSE. These results confirm that the apparent discrepancy between the results of Ginga (with \\alpha \\simeq 0.9) and the previous results of EXOSAT and HEAO (with \\alpha \\simeq 0.7) is indeed due to ionized absorption and Compton reflection first taken into account for Ginga but...

  4. Spectrum Synthesis Modeling of the X-ray Spectrum of GRO J1655-40 Taken During the 2005 Outburst

    CERN Document Server

    Kallman, T R; Goriely, Stephane; Mendoza, Claudio; Miller, Jon M; Palmeri, Patrick; Quinet, Pascal; Raymond, John

    2009-01-01

    The spectrum from the black hole X-ray transient GRO J1655-40. obtained using the $Chandra$ High Energy Transmission Grating (HETG) in 2005 is notable as a laboratory for the study of warm absorbers, and for the presence of many lines from odd-$Z$ elements between Na and Co (and Ti and Cr) not previously observed in X-rays. We present synthetic spectral models which can be used to constrain these element abundances and other parameters describing the outflow from the warm absorber in this object. We present results of fitting to the spectrum using various tools and techniques, including automated line fitting, phenomenological models, and photoionization modeling. We show that the behavior of the curves of growth of lines from H-like and Li-like ions indicate that the lines are either saturated or affected by filling-in from scattered or a partially covered continuum source. We confirm the conclusion of previous work by \\cite{Mill06} and \\cite{Mill08} which shows that the ionization conditions are not consist...

  5. X-Ray Polarimetry

    OpenAIRE

    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 ...

  6. A characterization of the NGC 4051 soft X-ray spectrum as observed by XMM-Newton

    CERN Document Server

    Nucita, A A; Longinotti, A L; Santos-Lleo, M; Maruccia, Y; Bianchi, S

    2010-01-01

    Soft X-rays high resolution spectroscopy of obscured AGNs shows the existence of a complex soft $X$-ray spectrum dominated by emission lines of He and H-like transitions of elements from Carbon to Neon, as well as L-shell transitions due to iron ions. In this paper we characterize the XMM-Newton RGS spectrum of the Seyfert 1 galaxy NGC 4051 observed during a low flux state and infer the physical properties of the emitting and absorbing gas in the soft X-ray regime. X-ray high-resolution spectroscopy offers a powerful diagnostic tool since the observed spectral features strongly depend on the physical properties of matter (ionization parameter U, electron density n_e, hydrogen column density N_H), which in turn are tightly related to the location and size of the X-ray emitting clouds. We carried out a phenomenological study to identify the atomic transitions detected in the spectra. This study suggests that the spectrum is dominated by emission from a photoionised plasma. Then, we used the photoionization code...

  7. An angle-dependent estimation of CT x-ray spectrum from rotational transmission measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yuan, E-mail: yuan.lin@duke.edu; Samei, Ehsan [Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina 27705 and Physics Department, Duke University, Durham, North Carolina 27708 (United States); Ramirez-Giraldo, Juan Carlos [Siemens Medical Solutions, Malvern, Pennsylvania 19355 (United States); Gauthier, Daniel J. [Physics Department, Duke University, Durham, North Carolina 27708 (United States); Stierstorfer, Karl [Siemens Healthcare, Forchheim 91301 (Germany)

    2014-06-15

    Purpose: Computed tomography (CT) performance as well as dose and image quality is directly affected by the x-ray spectrum. However, the current assessment approaches of the CT x-ray spectrum require costly measurement equipment and complicated operational procedures, and are often limited to the spectrum corresponding to the center of rotation. In order to address these limitations, the authors propose an angle-dependent estimation technique, where the incident spectra across a wide range of angular trajectories can be estimated accurately with only a single phantom and a single axial scan in the absence of the knowledge of the bowtie filter. Methods: The proposed technique uses a uniform cylindrical phantom, made of ultra-high-molecular-weight polyethylene and positioned in an off-centered geometry. The projection data acquired with an axial scan have a twofold purpose. First, they serve as a reflection of the transmission measurements across different angular trajectories. Second, they are used to reconstruct the cross sectional image of the phantom, which is then utilized to compute the intersection length of each transmission measurement. With each CT detector element recording a range of transmission measurements for a single angular trajectory, the spectrum is estimated for that trajectory. A data conditioning procedure is used to combine information from hundreds of collected transmission measurements to accelerate the estimation speed, to reduce noise, and to improve estimation stability. The proposed spectral estimation technique was validated experimentally using a clinical scanner (Somatom Definition Flash, Siemens Healthcare, Germany) with spectra provided by the manufacturer serving as the comparison standard. Results obtained with the proposed technique were compared against those obtained from a second conventional transmission measurement technique with two materials (i.e., Cu and Al). After validation, the proposed technique was applied to measure

  8. Energy spectrum analysis between single and dual energy source x-ray imaging for PCB non-destructive test

    Energy Technology Data Exchange (ETDEWEB)

    Park, Kyeong Jin; Kim, Myung Soo; Lee, Min Ju; Kang, Dong Uk; Lee, Dae Hee; Kim, Ye Won; Kim, Chan Kyu; Kim, Hyoung Taek; Kim, Gi Yoon; Cho, Gyu Seong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-08-15

    Reliability of printed circuit board (PCB), which is based on high integrated circuit technology, is having been important because of development of electric and self-driving car. In order to answer these demand, automated X-ray inspection (AXI) is best solution for PCB nondestructive test. PCB is consist of plastic, copper, and, lead, which have low to high Z-number materials. By using dual energy X-ray imaging, these materials can be inspected accurately and efficiently. Dual energy X-ray imaging, that have the advantage of separating materials, however, need some solution such as energy separation method and enhancing efficiency because PCB has materials that has wide range of Z-number. In this work, we found out several things by analysis of X-ray energy spectrum. Separating between lead and combination of plastic and copper is only possible with energy range not dose. On the other hand, separating between plastic and copper is only with dose not energy range. Moreover the copper filter of high energy part of dual X-ray imaging and 50 kVp of low energy part of dual X-ray imaging is best for efficiency.

  9. The NuSTAR X-ray Spectrum of Hercules X-1: A Radiation-Dominated Radiative Shock

    CERN Document Server

    Wolff, Michael T; Gottlieb, Amy M; Fürst, Felix; Hemphill, Paul B; Marcu-Cheatham, Diana M; Pottschmidt, Katja; Schwarm, Fritz-Walter; Wilms, Jörn; Wood, Kent S

    2016-01-01

    We report new spectral modeling of the accreting X-ray pulsar Hercules X- 1. Our radiation-dominated radiative shock model is an implementation of the analytic work of Becker & Wolff on Comptonized accretion flows onto magnetic neutron stars. We obtain a good fit to the spin-phase averaged 4 to 78 keV X-ray spectrum observed by the Nuclear Spectroscopic Telescope Array during a main- on phase of the Her X-1 35-day accretion disk precession period. This model allows us to estimate the accretion rate, the Comptonizing temperature of the radiating plasma, the radius of the magnetic polar cap, and the average scattering opacity parameters in the accretion column. This is in contrast to previous phenomenological models that characterized the shape of the X-ray spectrum but could not determine the physical parameters of the accretion flow. We describe the spectral fitting details and discuss the interpretation of the accretion flow physical parameters.

  10. 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.

  11. A Deep Chandra X-ray Spectrum of the Accreting Young Star TW Hydrae

    CERN Document Server

    Brickhouse, N S; Dupree, A K; Luna, G J M; Wolk, S

    2010-01-01

    We present X-ray spectral analysis of the accreting young star TW Hydrae from a 489 ks observation using the Chandra High Energy Transmission Grating. The spectrum provides a rich set of diagnostics for electron temperature T_e, electron density N_e, hydrogen column density N_H, relative elemental abundances and velocities and reveals its source in 3 distinct regions of the stellar atmosphere: the stellar corona, the accretion shock, and a very large extended volume of warm postshock plasma. The presence of Mg XII, Si XIII, and Si XIV emission lines in the spectrum requires coronal structures at ~10 MK. Lower temperature lines (e.g., from O VIII, Ne IX, and Mg XI) formed at 2.5 MK appear more consistent with emission from an accretion shock. He-like Ne IX line ratio diagnostics indicate that T_e = 2.50 +/- 0.25 MK and N_e = 3.0 +/- 0.2 x 10^(12) cm^(-3) in the shock. These values agree well with standard magnetic accretion models. However, the Chandra observations significantly diverge from current model pred...

  12. The Soft X-ray Spectrum from NGC 1068 Observed with LETGS on Chandra

    CERN Document Server

    Brinkman, A C; Van der Meer, R L J; Kinkhabwala, A; Behar, E; Kahn, S M; Paerels, F B S; Sako, M

    2002-01-01

    Using the combined spectral and spatial resolving power of the Low Energy Transmission Grating (LETGS) on board Chandra, we obtain separate spectra from the bright central source of NGC 1068 (Primary region), and from a fainter bright spot 4" to the NE (Secondary region). Both spectra are dominated by line emission from H- and He-like ions of C through S, and from Fe L-shell ions, but also include narrow radiative recombination continua, indicating that most of the soft X-ray emission arises in low-temperature (kT few eV) photoionized plasma. We confirm the conclusions of Kinkhabwala et al. (2002), based on XMM-Newton RGS observations, that the entire nuclear spectrum can be explained by recombination/radiative cascade following photoionization, and radiative decay following photoexcitation, with no evidence for hot, collisionally ionized plasma. In addition, this model also provides an excellent fit to the spectrum of the Secondary region, albeit with radial column densities a factor of three lower, as would...

  13. High energy x-ray reflectivity and scattering study from spectrum-x-gamma flight mirrors

    DEFF Research Database (Denmark)

    Christensen, Finn Erland; Budtz-Jørgensen, Carl; Frederiksen, P. Kk;

    1993-01-01

    Line radiation from Fe K-alpha(1), Cu K-alpha(1), and Ag K-alpha(1) is used to study the high energy X-ray reflectivity and scattering behavior of flight-quality X-ray mirrors having various Al substrates. When both the specular and the scattered radiation are integrated, near theoretical...

  14. Internal Bremsstrahlung spectrum from 57Co in coincidence with K-X rays

    International Nuclear Information System (INIS)

    In the present study, the IB photons from 57Co are measured in coincidence with 6.4 keV x rays emitted due to the EC process. The IB photons are measured using a (1.75 x 2.0 ) NaI(Tl) scintillation detector and k-x rays are detected using a proportional counter

  15. Astrophysical Fluids of Novae: High Resolution Pre-decay X-ray spectrum of V4743 Sagittarii

    OpenAIRE

    Ramírez-Velasquez, J. M.

    2016-01-01

    Eight X-ray observations of V4743 Sgr (2002), observed with Chandra and XMM-Newton are presented. The nova turned off some time between days 301.9 and 371, and the X-ray flux subsequently decreased from day 301.9 to 526 following an exponential decline time scale of $(96 \\pm 3)$ days. We use the absorption lines present in the SSS spectrum for diagnostic purposes, and characterize the physics and the dynamics of the expanding atmosphere during the explosion of the nova. The information extrac...

  16. Constraining the fraction of Compton-thick AGN in the Universe by modelling the diffuse X-ray background spectrum

    CERN Document Server

    Akylas, A; Georgantopoulos, I; Brightman, M; Nandra, K

    2012-01-01

    This paper investigates what constraints can be placed on the fraction of Compton-thick (CT) AGN in the Universe from the modeling of the spectrum of the diffuse X-ray background (XRB). We present a model for the synthesis of the XRB that uses as input a library of AGN X-ray spectra generated by the Monte Carlo simulations described by Brightman & Nandra. This is essential to account for the Compton scattering of X-ray photons in a dense medium and the impact of that process on the spectra of obscured AGN. We identify a small number of input parameters to the XRB synthesis code which encapsulate the minimum level of uncertainty in reconstructing the XRB spectrum. These are the power-law index and high energy cutoff of the intrinsic X-ray spectra of AGN, the level of the reflection component in AGN spectra and the fraction of CT AGN in the Universe. We then map the volume of the space allowed to these parameters by current observations of the XRB spectrum in the range 3-100 keV. One of the least constraine...

  17. An XMM-Newton observation of Ark 120: the X-ray spectrum of a `bare' Seyfert 1 nucleus

    CERN Document Server

    Vaughan, S; Ballantyne, D R; De Rosa, A; Piro, L; Matt, G

    2004-01-01

    We report on a long (100 ks) XMM-Newton observation of the bright Seyfert 1 galaxy Arakelian 120. The source previously showed no signs of intrinsic reddening in its infrared-ultraviolet continuum and previous observations had shown no evidence for ionized absorption in either the ultraviolet or X-ray bands. The new XMM-Newton RGS data place tight limits on the presence of an ionized X-ray absorber and confirm that the X-ray spectrum of Ark 120 is essentially unmodified by intervening matter. Thus Ark 120 can be considered a `bare' Seyfert 1 nucleus. This observation therefore offers a clean view of the X-ray spectrum of a `normal' Seyfert galaxy free from absorption effects. The spectrum shows a Doppler broadened iron emission line (FWHM ~ 3*10^4 km/s) and a smooth, continuous soft excess which appears to peak at an energy ~0.5 keV. This adds weight to the claim that genuine soft excesses (i.e. those due to a real steepening of the underlying continuum below ~2 keV) are ubiquitous in Seyfert 1 spectra. Howev...

  18. 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.

  19. 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...

  20. 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.

  1. Probing the clumping structure of Giant Molecular Clouds through the spectrum, polarisation and morphology of X-ray Reflection Nebulae

    CERN Document Server

    Molaro, Margherita; Sunyaev, Rashid

    2015-01-01

    We suggest a method for probing global properties of clump populations in Giant Molecular Clouds (GMCs) in the case where these act as X-ray reflection nebulae (XRNe), based on the study of the clumping's overall effect on the reflected X-ray signal, in particular on the Fe K-alpha line's shoulder. We consider the particular case of Sgr B2, one of the brightest and most massive XRN in our Galaxy. We parametrise the gas distribution inside the cloud using a simple clumping model, with the slope of the clump mass function (alpha), the minimum clump mass (m_{min}), the fraction of the cloud's mass contained in clumps (f_{DGMF}), and the mass-size relation of individual clumps as free parameters, and investigate how these affect the reflected X-ray spectrum. In the case of very dense clumps, similar to those presently observed in Sgr B2, these occupy a small volume of the cloud and present a small projected area to the incoming X-ray radiation. We find that these contribute negligibly to the scattered X-rays. Clu...

  2. The continuous spectrum of Markarian 421 during periods of X-ray satellite observations

    Science.gov (United States)

    Mufson, S. L.; Wood, K.; Mcnutt, D. P.; Yentis, D. J.; Meekins, J. F.; Byram, E. T.; Chubb, T. A.; Friedman, H.; Wisniewski, W. Z.

    1980-01-01

    New UBVRI photometry of Mrk 421 obtained during periods of X-ray satellite observations are presented. An X-ray light curve for 1977 November from the HEAO A-1 experiment is also given. The decomposition of the UBVR fluxes into a compact nonthermal component and an extended galactic component shows that there are coordinated variations in the optical nonthermal and X-ray emission. The data are consistent with the hypothesis that the mini-BL Lac object is emitting by the synchrontron-self-Compton process. The host galaxy of this composite source has properties like those of a giant elliptical.

  3. 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.

  4. 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.

  5. Moving the Frontier of Quantum Control into the Soft X-Ray Spectrum

    Directory of Open Access Journals (Sweden)

    A. Aquila

    2011-01-01

    Full Text Available The femtosecond nature of X-ray free electron laser (FEL pulses opens up exciting research possibilities in time-resolved studies including femtosecond photoemission and diffraction. The recent developments of seeding X-ray FELs extend their capabilities by creating stable, temporally coherent, and repeatable pulses. This in turn opens the possibility of spectral engineering soft X-ray pulses to use as a probe for the control of quantum dynamics. We propose a method for extending coherent control pulse-shaping techniques to the soft X-ray spectral range by using a reflective geometry 4f pulse shaper. This method is based on recent developments in asymmetrically cut multilayer optic technology and piezoelectric substrates.

  6. The first high-resolution X-ray spectrum of a Herbig Star: The case of AB Aurigae

    CERN Document Server

    Telleschi, A; Briggs, K R; Skinner, S L; Audard, M; Franciosini, E

    2006-01-01

    We present the first high-resolution X-ray spectrum of a prototypical Herbig star (AB Aurigae), measure and interpret various spectral features, and compare our results with model predictions. We use X-ray spectroscopy data from XMM-Newton. The spectra are interpreted using thermal, optically thin emission models with variable element abundances and a photoelectric absorption component. We interpret line flux ratios in He-like triplet of O VII as a function of electron density and the UV radiation field. We use the nearby co-eval classical T Tauri star SU Aur as a comparison. AB Aurigae reveals a soft X-ray spectrum, most plasma being concentrated at 1-6 MK. The He-like triplet reveals no signatures of increased densities and there are no clear indications for strong abundance anomalies. The light curve displays modulated variability, with a period of ~ 42 hr. It is unlikely that a nearby, undetected lower-mass companion is the source of the X-rays. Accretion shocks close to the star should be irradiated by t...

  7. A Change in the Quiescent X-Ray Spectrum of the Neutron Star Low-mass X-Ray Binary MXB 1659-29

    NARCIS (Netherlands)

    E.M. Cackett; E.F. Brown; A. Cumming; N. Degenaar; J. Fridriksson; J. Homan; J.M. Miller; R. Wijnands

    2013-01-01

    The quasi-persistent neutron star low-mass X-ray binary MXB 1659-29 went into quiescence in 2001, and we have followed its quiescent X-ray evolution since. Observations over the first 4 yr showed a rapid drop in flux and temperature of the neutron star atmosphere, interpreted as cooling of the neutr

  8. A redetermination of the X-ray spectrum of SN 1006 and excess diffuse emission from the Lupus region

    International Nuclear Information System (INIS)

    X-ray from SN 1006 and from the adjacent Lupus region were separately observed with the Tenma gas scintillation proportional counters. The spectrum of the local excess emission from the Lupus region can be consistently fitted with either a thin thermal bremsstrahlung spectrum with a temperature of 7.5 ± 2.6 keV or a power-law spectrum with a photon index of 2.1 ± 0.1. The x-ray emission from SN 1006, after subtraction of this local excess, has a spectrum which can be described as a power-law spectrum with a photon index of 3.3 ± 0.1 or a thin thermal bremsstrahlung spectrum with a temperature of 1.9 ± 0.1 keV which is much softer than the previously reported spectrum. No significant iron line emission was observed in the SN 1006 spectrum. The 90 % upper limit for the equivalent width of the iron line was reduced to 400 eV. The observed spectrum can also be interpreted in terms of a nonequilibrium ionization model of about 2-keV electron temperature. (author)

  9. The 1 keV to 200 keV X-ray Spectrum of NGC 2992 and NGC 3081

    CERN Document Server

    Beckmann, Volker; Tueller, Jack

    2007-01-01

    The Seyfert 2 galaxies NGC 2992 and NGC 3081 have been observed by INTEGRAL and Swift. We report about the results and the comparison of the spectrum above 10 keV based on INTEGRAL IBIS/ISGRI, Swift/BAT, and BeppoSAX/PDS. A spectrum can be extracted in the X-ray energy band ranging from 1 keV up to 200 keV. Although NGC 2992 shows a complex spectrum below 10 keV, the hard tail observed by various missions exhibits a slope with photon index = 2, independent on the flux level during the observation. No cut-off is detectable up to the detection limit around 200 keV. In addition, NGC 3081 is detected in the INTEGRAL and Swift observation and also shows an unbroken Gamma = 1.8 spectrum up to 150 keV. These two Seyfert galaxies give further evidence that a high-energy cut-off in the hard X-ray spectra is often located at energies E_C >> 100 keV. In NGC 2992 a constant spectral shape is observed over a hard X-ray luminosity variation by a factor of 11. This might indicate that the physical conditions of the emitting...

  10. 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.

  11. The highly variable X-ray spectrum of the luminous Seyfert 1 galaxy 1H 0419-577

    CERN Document Server

    Page, K L; Reeves, J N; O'Brien, P T

    2002-01-01

    An XMM-Newton observation of the luminous Seyfert 1 galaxy 1H 0419-577 is presented. We find that the spectrum is well fitted by a power law of canonical slope (gamma ~ 1.9) and 3 blackbody components (to model the strong soft excess). The XMM data are compared and contrasted with observations by ROSAT in 1992 and by ASCA and BeppoSAX in 1996. We find that the overall X-ray spectrum has changed substantially over the period, and suggest that the changes are driven by the soft X-ray component. When bright, as in our XMM-Newton observation, it appears that the enhanced soft flux cools the Comptonising corona, causing the 2-10 keV power law to assume a `typical' slope, in contrast to the unusually hard (`photon-starved') spectra observed by ASCA and BeppoSAX four years earlier.

  12. Constraints on the Physics of Type Ia Supernovae from the X-Ray Spectrum of the Tycho Supernova Remnant

    CERN Document Server

    Badenes, C; Hughes, J P; Hwang, U; Bravo, E; Badenes, Carles; Borkowski, Kazimierz J.; Hughes, John P.; Hwang, Una; Bravo, Eduardo

    2005-01-01

    In this paper we use high quality X-ray observations from XMM-Newton and Chandra to gain new insights into the explosion that originated Tycho's supernova 433 years ago. We perform a detailed comparison between the ejecta emission from the spatially integrated X-ray spectrum of the supernova remnant and current models for Type Ia supernova explosions. We use a grid of synthetic X-ray spectra based on hydrodynamic models of the evolution of the supernova remnant and self-consistent nonequilibrium ionization calculations for the state of the shocked plasma. We find that the fundamental properties of the X-ray emission in Tycho are well reproduced by a one-dimensional delayed detonation model with a kinetic energy of 1.2e51 erg. All the other paradigms for Type Ia explosions that we have tested fail to provide a good approximation to the observed ejecta emission, including one-dimensional deflagrations, pulsating delayed detonations and sub-Chandrasekhar explosions, as well as deflagration models calculated in t...

  13. The Solar Flare 4: 10 keV X-ray Spectrum

    Science.gov (United States)

    Phillips, K. J. H.

    2004-01-01

    The 4-10 keV solar flare spectrum includes highly excited lines of stripped Ca, Fe, and Ni ions as well as a continuum steeply falling with energy. Groups of lines at approximately 7 keV and approximately 8 keV, observed during flares by the broad-band RHESSI spectrometer and called here the Fe-line and Fe/Ni-line features, are formed mostly of Fe lines but with Ni lines contributing to the approximately 8 keV feature. Possible temperature indicators of these line features are discussed - the peak or centroid energies of the Fe-line feature, the line ratio of the Fe-line to the Fe/Ni-line features, and the equivalent width of the Fe-line feature. The equivalent width is by far the most sensitive to temperature. However, results will be confused if, as is commonly believed, the abundance of Fe varies from flare to flare, even during the course of a single flare. With temperature determined from the thermal continuum, the Fe-line feature becomes a diagnostic of the Fe abundance in flare plasmas. These results are of interest for other hot plasmas in coronal ionization equilibrium such as stellar flare plasmas, hot gas in galaxies, and older supernova remnants.

  14. Performance of microstrip proportional counters for x-ray astronomy on spectrum-roentgen-gamma

    DEFF Research Database (Denmark)

    Budtz-Jørgensen, Carl; BAHNSEN, A; Christensen, Finn Erland;

    1991-01-01

    DSRI will provide a set of four imaging proportional counters for the Danish-Soviet X-ray telescopes XSPECT/SODART. The sensor principle is based on the novel micro-strip proportional counter (MSPC), where the strip electrodes are deposited by photolithography onto a rigid substrate. The MSPC off...

  15. Quenching the X-ray spectrum of hot halos with AGN outflows and turbulence

    Science.gov (United States)

    Gaspari, M.

    2016-06-01

    I highlight recent advancements in the astrophysics of AGN outflow feedback and diffuse hot gas. Thanks to XMM RGS resolution, we know that the X-ray cores of clusters, groups, and massive galaxies have a strong deficit of soft X-ray emission compared with the classic cooling flow prediction: dL_{x}/dT ∝ (T/T_{hot})^{2±1}. Using 3D hydrodynamic simulations, I show that such deficit arises from the tight self-regulation between thermal instability condensation and AGN outflow feedback. Multiphase filaments condense out of the hot plasma, they rain onto the central SMBH, and boost the AGN outflows via chaotic cold accretion. The sub-relativistic outflows thermalize in the core via shocks and turbulence, releasing more heat in the inner cooler phase, thus inducing the observed soft X-ray decline. I discuss how we can leverage XMM capabilities in the next decade by probing turbulence, conduction, AGN accretion and outflows via the information contained in X-ray spectra and surface brightness. I focus on the importance of selecting a few objects with Ms exposure and how we can unveil multiphase halos through the synergy between simulations and multiwavelength observations.

  16. A strong and broad Fe line in the XMM-Newton spectrum of the new X-ray transient and black hole candidate XTEJ1652-453

    NARCIS (Netherlands)

    Hiemstra, Beike; Mendez, Mariano; Done, Chris; Diaz Trigo, Maria; Altamirano, Diego; Casella, Piergiorgio

    2011-01-01

    We observed the new X-ray transient and black hole candidate XTEJ1652-453 simultaneously with XMM-Newton and the Rossi X-ray Timing Explorer (RXTE). The observation was done during the decay of the 2009 outburst, when XTEJ1652-453 was in the hard-intermediate state. The spectrum shows a strong and b

  17. A NuSTAR observation of the reflection spectrum of the low-mass X-ray binary 4U 1728-34

    DEFF Research Database (Denmark)

    Sleator, Clio C.; Tomsick, John A.; King, Ashley L.;

    2016-01-01

    We report on a simultaneous NuSTAR and Swift observation of the neutron star low-mass X-ray binary 4U 1728-34. We identified and removed four Type I X-ray bursts during the observation in order to study the persistent emission. The continuum spectrum is hard and described well by a blackbody with...

  18. Impulsive solar X-ray bursts. III - Polarization, directivity, and spectrum of the reflected and total bremsstrahlung radiation from a beam of electrons directed toward the photosphere

    Science.gov (United States)

    Langer, S. H.; Petrosian, V.

    1977-01-01

    The paper presents the spectrum, directivity, and state of polarization of the bremsstrahlung radiation expected from a beam of high-energy electrons spiraling along radial magnetic field lines toward the photosphere. A Monte Carlo method is then described for evaluation of the spectrum, directivity, and polarization of X-rays diffusely reflected from stellar photospheres. The accuracy of the technique is evaluated through comparison with analytic results. The calculated characteristics of the incident X-rays are used to evaluate the spectrum, directivity, and polarization of the reflected and total X-ray fluxes. The results are compared with observations.

  19. X-ray fluorescence spectrum of highly charged Fe ions driven by strong free-electron-laser fields

    Science.gov (United States)

    Oreshkina, Natalia S.; Cavaletto, Stefano M.; Keitel, Christoph H.; Harman, Zoltán

    2016-05-01

    The influence of nonlinear dynamical effects is analyzed on the observed spectra of controversial 3C and 3D astrophysically relevant x-ray lines in neonlike Fe{}16+ and the A, B, and C lines in natriumlike Fe{}15+ ions. First, a large-scale configuration-interaction calculation of oscillator strengths is performed with the inclusion of higher-order electron-correlation effects. Also, quantum-electrodynamic corrections to the transition energies are calculated. Further considered dynamical effects provide a possible resolution of the discrepancy between theory and experiment found by recent x-ray free-electron-laser measurements of these controversial lines. We find that, for strong x-ray sources, the modeling of the spectral lines by a peak with an area proportional to the oscillator strength is not sufficient and nonlinear dynamical effects have to be taken into account. Thus, we advocate the use of light–matter-interaction models also valid for strong light fields in the analysis and interpretation of the associated astrophysical and laboratory spectra. We investigate line-strength ratios distinguishing between the coherent and incoherent parts of the emission spectrum. In addition, the spectrum of Fe{}15+, an autoionizing ion which was also present in the recent laboratory experiment, is analyzed as well.

  20. The NuSTAR X-ray Spectrum of Hercules X-1: A Radiation-Dominated Radiative Shock

    Science.gov (United States)

    Wolff, Michael Thomas; Becker, Peter A.; Gottlieb, Amy; Fuerst, Felix; Britton Hemphill, Paul; Marcu-Cheatham, Diana; Pottschmidt, Katja; Schwarm, Fritz-Walter; Wilms, Joern; Wood, Kent

    2016-04-01

    We report on new spectral modeling of an observation of the accreting X-ray pulsar Her X-1 by the Nuclear Spectroscopic Telescope Array (NuSTAR). We utilize a radiation-dominated radiative shock model that is an implementation of the analytic work of Becker & Wolff (2007) on Comptonized accretion flows onto magnetic neutron stars within the XSPEC analysis environment. We obtain a good fit to the Her X-1 spin-phase averaged 4 to 78 keV X-ray spectrum observed by NuSTAR during a main-on phase of the Her X-1 35-day accretion disk precession period. This model allows us to estimate the accretion rate, the Comptonizing temperature of the radiating plasma, the radius of the magnetic polar cap, and the average scattering opacity parameters in the accretion column. This is in contrast to previous spectral models that characterized the shape of the X-ray spectrum but could not determine the physical parameters of the accretion flow. We describe the details of our spectral fitting model and we discuss the interpretation of the resulting accretion flow physical parameters.This research is supported by the NASA Astrophysics Data Analysis Program.

  1. The high energy X-ray spectrum of 4U 1700-37 observed from OSO 8

    Science.gov (United States)

    Dolan, J. F.; Coe, M. J.; Crannell, C. J.; Dennis, B. R.; Frost, K. J.; Orwig, L. E.; Maurer, G. S.

    1980-01-01

    The most intense hard X-ray source in the confused region in Scorpius has been identified as 4U 1700-37 (=HD 153919). Observations extending over three binary periods in 1978 September were carried out with the high-energy X-ray spectrometer on OSO 8. The 3.4 day modulation is seen above 20 keV with the intensity during eclipse being consistent with zero flux. The photonumber spectrum from 20 to 150 keV is well represented by a single power law with a photonumber spectral index of -2.77 + or - 0.35 or by a thermal bremsstrahlung spectrum with kT = 27 (+15, -7)keV. The counting rate above 20 keV outside of eclipse shows no evidence for the 96.8 minute X-ray modulation previously reported at lower energies. Despite the difficulties that exist in reconciling both the lack of periodic modulation in the emitted X-radiation and the orbital dynamics of the system with our currently accepted theories of the evolution and physical properties of neutron stars, the observed properties of 4U 1700-37 are all consistent with the source being a spherically accreting neutron star rather than a black hole.

  2. Design of Time-Resolved Shifted Dual Transmission Grating Spectrometer for the X-Ray Spectrum Diagnostics

    Science.gov (United States)

    Wang, Baoqing; Yi, Tao; Wang, Chuanke; Zhu, Xiaoli; Li, Tingshuai; Li, Jin; Liu, Shenye; Jiang, Shaoen; Ding, Yongkun

    2016-07-01

    A new time-resolved shifted dual transmission grating spectrometer (SDTGS) is designed and fabricated in this work. This SDTGS uses a new shifted dual transmission grating (SDTG) as its dispersive component, which has two sub transmission gratings with different line densities, of 2000 lines/mm and 5000 lines/mm. The axes of the two sub transmission gratings in SDTG are horizontally and vertically shifted a certain distance to measure a broad range of 0.1-5 keV time-resolved X-ray spectra. The SDTG has been calibrated with a soft X-ray beam of the synchrotron radiation facility and its diffraction efficiency is also measured. The designed SDTGS can take full use of the space on a record panel and improve the precision for measuring spatial and temporal spectrum simultaneously. It will be a promising application for accurate diagnosis of the soft X-ray spectrum in inertial confinement fusion. supported by National Natural Science Foundation of China (Nos. 11405158 and 11435011) and Development Foundation of China Academy of Engineering Physics (Nos. 2014B0102011 and 2014B0102012)

  3. No Signatures of Black-Hole Spin in the X-ray Spectrum of the Seyfert 1 Galaxy Fairall 9

    CERN Document Server

    Yaqoob, Tahir; Tatum, Malachi M; Trevor, Max; Scholtes, Alexis

    2016-01-01

    Fairall 9 is one of several type 1 active galactic nuclei for which it has been claimed that the angular momentum (or spin) of the supermassive black hole can be robustly measured, using the Fe K$\\alpha$ emission line and Compton-reflection continuum in the X-ray spectrum. The method rests upon the interpretation of the Fe K$\\alpha$ line profile and associated Compton-reflection continuum in terms of relativistic broadening in the strong gravity regime in the innermost regions of an accretion disc, within a few gravitational radii of the black hole. Here, we re-examine a Suzaku X-ray spectrum of Fairall 9 and show that a face-on toroidal X-ray reprocessor model involving only nonrelativistic and mundane physics provides an excellent fit to the data. The Fe K$\\alpha$ line emission and Compton reflection continuum are calculated self-consistently, the iron abundance is solar, and an equatorial column density of $\\sim 10^{24} \\ \\rm cm^{-2}$ is inferred. In this scenario, neither the Fe K$\\alpha$ line, nor the Co...

  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. A review of advantages of high-efficiency X-ray spectrum imaging for analysis of nanostructured ferritic alloys

    International Nuclear Information System (INIS)

    Nanostructured ferritic alloys (NFAs) exhibit complex microstructures consisting of 100–500 nm ferrite grains, grain boundary solute enrichment, and multiple populations of precipitates and nanoclusters (NCs). Understanding these materials’ excellent creep and radiation-tolerance properties requires a combination of multiple atomic-scale experimental techniques. Recent advances in scanning transmission electron microscopy (STEM) hardware and data analysis methods have the potential to revolutionize nanometer-to micrometer-scale materials analysis. Modern high-brightness, high-X-ray collection STEM instruments are capable of enabling advanced experiments, such as simultaneous energy dispersive X-ray spectroscopy and electron energy loss spectroscopy spectrum imaging at nm to sub-nm resolution, that are now well-established for the study of nuclear materials. In this paper, we review past results and present new results illustrating the effectiveness of latest-generation STEM instrumentation and data analysis

  6. A review of advantages of high-efficiency X-ray spectrum imaging for analysis of nanostructured ferritic alloys

    Science.gov (United States)

    Parish, Chad M.; Miller, Michael K.

    2015-07-01

    Nanostructured ferritic alloys (NFAs) exhibit complex microstructures consisting of 100-500 nm ferrite grains, grain boundary solute enrichment, and multiple populations of precipitates and nanoclusters (NCs). Understanding these materials' excellent creep and radiation-tolerance properties requires a combination of multiple atomic-scale experimental techniques. Recent advances in scanning transmission electron microscopy (STEM) hardware and data analysis methods have the potential to revolutionize nanometer-to micrometer-scale materials analysis. Modern high-brightness, high-X-ray collection STEM instruments are capable of enabling advanced experiments, such as simultaneous energy dispersive X-ray spectroscopy and electron energy loss spectroscopy spectrum imaging at nm to sub-nm resolution, that are now well-established for the study of nuclear materials. In this paper, we review past results and present new results illustrating the effectiveness of latest-generation STEM instrumentation and data analysis.

  7. X-ray Lβ215 emission spectrum of Ru in Ru(NH3)6Cl3

    International Nuclear Information System (INIS)

    One of the broader applications of synchrotron radiation has been to EXAFS studies for material structure determination, i.e., for an analysis of x-ray absorption over an extended energy region beyond a core ionization limit. Studies of the near edge structure (XANES) give a different type of information, characteristic of the local symmetry and electronic configuration of the absorbing atom. This type of information is reflected also in the x-ray emission spectra, in particular for transitions involving the valence levels. Examination of the near edge absorption or the emission spectrum does not require an instrument capable of scanning a wide energy range with high counting statistics, as does EXAFS; the needs are rather for good resolution and a reliable calibration of the energy scale. Some of the problems of near edge spectra were particularly evident in our investigation of Ru-Lβ215 emission from Ru(NH3)6Cl3. The Ru-Lβ215 emission was measured with a laboratory Rowland circle x-ray spectrometer with a curved quartz (1010) crystal (radius = 22 inches) in a fixed position appropriate to the energy range, and a position sensitive detector which can be positioned along the Rowland circle. The Ru spectrum was excited mainly by Sn-L/sub α/ primary radiation from a Sn anode in a demountable x-ray tube operating at 13 kV and 120 mA. The resolution of the instrument in this region is 1.5 eV. An accurate calibration of the energy scale was conveniently obtained by measuring a reference x-ray emission line in the same instrumental configuration. In the present case the Pd-L/sub α/ emission line at 2838 eV was used to establish the energy scale. The energy dispersion of the instrument was determined from the Cl-K/sub β/ emission spectrum of CH3Cl between 2810 eV and 2830 eV and Pd-Lα12 and extrapolated to the energy region of the recorded emission spectrum. 6 references, 1 figure

  8. 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

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

    International Nuclear Information System (INIS)

    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 ∼ 5.5 and galaxies out to z ∼ 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 ∼58% of X-ray Seyferts (1042 erg s–1 2–10keV 44 erg s–1) require a starburst event (>5% starburst contribution to bolometric luminosity) to fit observed photometry only 26% of the X-ray QSO (L2–10keV >1044 erg s–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 activity. We have tested the hypothesis that there should be a

  10. Evidence for Resonance Scattering in the X-ray Spectrum of Zeta Puppis

    Science.gov (United States)

    Leutenegger, Maurice

    2008-01-01

    We present XMM-Newton Reflection Grating Spectrometer observations of pairs of X-ray emission line profiles from the 0 star Zeta Pup that originate from the same He-like ion. The two profiles in each pair have different shapes and cannot both be consistently fit by models assuming the same wind parameters. We show that the differences in profile shape can be accounted for in a model including the effects of resonance scattering, which affects the resonance line in the pair but not the intercombination line. This implies that resonance scattering is also important in single resonance lines, where its effect is difficult to distinguish from a low effective continuum optical depth in the wind. Thus, resonance scattering may help reconcile X-ray line profile shapes with literature mass-loss rates.

  11. X-Ray Photoelectron Spectrum Analysis of Yb3C60 Compound

    Institute of Scientific and Technical Information of China (English)

    CAO Xue-Wei; SHAO Yue; WANG Yu-Fang; LAN Guo-Xiang

    2001-01-01

    The nominal composition of the Yb3 C60 compound is characterized by means of x-ray photoelectron spectroscopy.Evidence of the divalent state for the Yb cation in the as-grown crystalline Yb3C60 is obtained. After exposure to air, the Yb3C60 compound transforms to an amorphous phase and Yb2O3 compound, while the valence state of the Yb cations changes from divalent to trivalent.

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

    NARCIS (Netherlands)

    M. Del Santo; T.M. Belloni; J. Homan; A. Bazzano; P. Casella; R.P. Fender; E. Gallo; N. Gehrels; W.H.G. Lewin; M. Méndez; M. van der Klis

    2009-01-01

    We report on X-ray and soft γ-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 evolu

  13. Broadband X-ray edge-enhancement imaging of a boron fibre on lithium fluoride thin film detector

    Science.gov (United States)

    Nichelatti, E.; Bonfigli, F.; Vincenti, M. A.; Cecilia, A.; Vagovič, P.; Baumbach, T.; Montereali, R. M.

    2016-10-01

    The white beam (∼6-80 keV) available at the TopoTomo X-ray beamline of the ANKA synchrotron facility (KIT, Karlsruhe, Germany) was used to perform edge-enhancement imaging tests on lithium fluoride radiation detectors. The diffracted X-ray image of a microscopic boron fibre, consisting of tungsten wire wrapped by boron cladding, was projected onto lithium fluoride thin films placed at several distances, from contact to 1 m . X-ray photons cause the local formation of primary and aggregate colour centres in lithium fluoride; these latter, once illuminated under blue light, luminesce forming visible-light patterns-acquired by a confocal laser scanning microscope-that reproduce the intensity of the X-ray diffracted images. The tests demonstrated the excellent performances of lithium fluoride films as radiation detectors at the investigated photon energies. The experimental results are here discussed and compared with those calculated with a model that takes into account all the processes that concern image formation, storing and readout.

  14. ART-XC: A Medium-energy X-ray Telescope System for the Spectrum-R-Gamma Mission

    Science.gov (United States)

    Arefiev, V.; Pavlinsky, M.; Lapshov, I.; Thachenko, A.; Sazonov, S.; Revnivtsev, M.; Semena, N.; Buntov,M.; Vikhlinin, A.; Gubarev, M.; ODell, S.; Ramsey, B.; Romaine, S.; Swartz. D/; Weisskopf, M.; Hasinger, G.; Predehl, P.; Grigorovich, S.; Litvin, D.; Meidinger, N.; Strueder, L. W.

    2008-01-01

    The ART-XC instrument is an X-ray grazing-incidence telescope system in an ABRIXAS-type optical configuration optimized for the survey observational mode of the Spectrum-RG astrophysical mission which is scheduled to be launched in 2011. ART-XC has two units, each equipped with four identical X-ray multi-shell mirror modules. The optical axes of the individual mirror modules are not parallel but are separated by several degrees to permit the four modules to share a single CCD focal plane detector, 1/4 of the area each. The 450-micron-thick pnCCD (similar to the adjacent eROSITA telescope detector) will allow detection of X-ray photons up to 15 keV. The field of view of the individual mirror module is about 18 x 18 arcminutes(exp 2) and the sensitivity of the ART-XC system for 4 years of survey will be better than 10(exp -12) erg s(exp -1) cm(exp -2) over the 4-12 keV energy band. This will allow the ART-XC instrument to discover several thousand new AGNs.

  15. The soft X-ray spectrum of the high-mass X-ray binary V0332+53 in quiescence

    Science.gov (United States)

    Elshamouty, Khaled G.; Heinke, Craig O.; Chouinard, Rhys

    2016-11-01

    The behaviour of neutron stars in high-mass X-ray binaries (HMXBs) during periods of low mass transfer is of great interest. Indications of spectral softening in systems at low mass-transfer rates suggest that some HMXBs are undergoing fundamental changes in their accretion regime, but the nature of the quiescent X-ray emission is not clear. We performed a 39 ks XMM-Newton observation of the transient HMXB V0332+53, finding it at a very low X-ray luminosity (Lx ˜ 4 × 1032 erg s-1). A power-law spectral fit requires an unusually soft spectral index (4.4^{+0.9}_{-0.6}), while a magnetized neutron star atmosphere model, with temperature LogTeff 6.7 ± 0.2 K and inferred emitting radius of ˜0.2-0.3 km, gives a good fit. We suggest that the quiescent X-ray emission from V0332+53 is mainly from a hotspot on the surface of the neutron star. No conclusions on the presence of pulsations could be drawn due to the low count rate. Due to the high absorption column, thermal emission from the rest of the neutron star could be only weakly constrained, to LogTeff <6.14^{+0.05}_{-6.14} K, or <3 × 1033 erg s-1.

  16. Technical Note: spektr 3.0—A computational tool for x-ray spectrum modeling and analysis

    Science.gov (United States)

    Punnoose, J.; Xu, J.; Sisniega, A.; Zbijewski, W.; Siewerdsen, J. H.

    2016-01-01

    Purpose: A computational toolkit (spektr 3.0) has been developed to calculate x-ray spectra based on the tungsten anode spectral model using interpolating cubic splines (TASMICS) algorithm, updating previous work based on the tungsten anode spectral model using interpolating polynomials (TASMIP) spectral model. The toolkit includes a matlab (The Mathworks, Natick, MA) function library and improved user interface (UI) along with an optimization algorithm to match calculated beam quality with measurements. Methods: The spektr code generates x-ray spectra (photons/mm2/mAs at 100 cm from the source) using TASMICS as default (with TASMIP as an option) in 1 keV energy bins over beam energies 20–150 kV, extensible to 640 kV using the TASMICS spectra. An optimization tool was implemented to compute the added filtration (Al and W) that provides a best match between calculated and measured x-ray tube output (mGy/mAs or mR/mAs) for individual x-ray tubes that may differ from that assumed in TASMICS or TASMIP and to account for factors such as anode angle. Results: The median percent difference in photon counts for a TASMICS and TASMIP spectrum was 4.15% for tube potentials in the range 30–140 kV with the largest percentage difference arising in the low and high energy bins due to measurement errors in the empirically based TASMIP model and inaccurate polynomial fitting. The optimization tool reported a close agreement between measured and calculated spectra with a Pearson coefficient of 0.98. Conclusions: The computational toolkit, spektr, has been updated to version 3.0, validated against measurements and existing models, and made available as open source code. Video tutorials for the spektr function library, UI, and optimization tool are available.

  17. 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...

  18. Prediction soft-X-ray spectrum of solar flares from Very Low Frequency observations: an inverse problem in ionospheric science

    Science.gov (United States)

    Palit, Sourav; Chakrabarti, Sandip Kumar; Ray, Suman

    2016-07-01

    Earth's lower ionosphere and upper atmosphere absorb X-rays and gamma-rays from astronomical sources such as solar flares, Short Gamma ray Repeaters (SGRs) or Gamma Ray Bursts (GRBs). The electron-ion production rates due to the ionization of such energetic photons at different heights depend on the intensity and wavelength of the injected spectrum and hence vary from one source to another. Obviously the ion density vs. altitude profile has the imprint of the incident photon spectrum. In this paper, we examine the possibility of inverting the electron density-height profiles uniquely by deconvolution of the VLF amplitude signal to obtain information on the injected spectrum. We have been able to reproduce the soft-X-ray part of the injected spectra from two different classes of solar flares with satisfactory accuracy. With the possibilities of probing even lower parts of the atmosphere, the method presented here is useful to carry out a similar exercise to infer the higher energy part of solar flare spectra and spectra of more energetic events such as the GRBs, SGRs etc. We show that to a certain accuracy, the Earth's atmosphere may be used as a gigantic detector of relatively strong ionizing extra-terrestrial events.

  19. Inverse problem in ionospheric science: prediction of solar soft-X-ray spectrum from very low frequency radiosonde results

    Science.gov (United States)

    Palit, S.; Ray, S.; Chakrabarti, S. K.

    2016-05-01

    X-rays and gamma-rays from astronomical sources such as solar flares are mostly absorbed by the Earth's atmosphere. Resulting electron-ion production rate as a function of height depends on the intensity and wavelength of the injected spectrum and therefore the effects vary from one source to another. In other words, the ion density vs. altitude profile has the imprint of the incident photon spectrum. In this paper, we investigate whether we can invert the problem uniquely by deconvolution of the VLF amplitude signal to obtain the details of the injected spectrum. We find that it is possible to do this up to a certain accuracy. This leads us to the possibility of uninterrupted observation of X-ray photon spectra of solar flares that are often hindered by the restricted observation window of space satellites to avoid charge particle damages. Such continuous means of observation are essential in deriving information on time evolution of physical processes related to electron acceleration and interaction with plasma in solar atmosphere. Our method is useful to carry out a similar exercise to infer the spectra of more energetic events such as the Gamma Ray Bursts (GRBs), Soft Gamma-ray Repeaters (SGRs) etc., by probing even the lower part of the Earth's atmosphere. We thus show that to certain extent, the Earth's atmosphere could be used as a gigantic detector of relatively strong astronomical events.

  20. The Soft X-ray Spectrum from NGC 1068 Observed with LETGS on Chandra

    OpenAIRE

    Brinkman, A. C.; Kaastra, J.S.; Van Der Meer, R.L.J.; Kinkhabwala, A.; Behar, E; Kahn, S. M.; Paerels, F. B. S.; Sako, M.

    2002-01-01

    Using the combined spectral and spatial resolving power of the Low Energy Transmission Grating (LETGS) on board Chandra, we obtain separate spectra from the bright central source of NGC 1068 (Primary region), and from a fainter bright spot 4" to the NE (Secondary region). Both spectra are dominated by line emission from H- and He-like ions of C through S, and from Fe L-shell ions, but also include narrow radiative recombination continua, indicating that most of the soft X-ray emission arises ...

  1. Detection of Nitrogen and Neon in the X-ray Spectrum of GP Com with XMM/Newton

    Science.gov (United States)

    Strohmayer, Tod E.

    2004-01-01

    We report on X-ray spectroscopic observations with XMM/Newton of the ultra-compact, double white dwarf binary, GP Com. With the Reflection Grating Spectrometers (RGS) we detect the L(alpha) and L(beta) lines of hydrogen-like nitrogen (N VII) and neon (Ne X), as well as the helium-like triplets (N VI and Ne IX) of these same elements. All the emission lines are unresolved. These are the first detections of X-ray emission lines from a double-degenerate, AM CVn system. We detect the resonance (r) and intercombination (i) lines of the N VI triplet, but not the forbidden (f) line. The implied line ratios for N VI, R = f/i less than 0.3, and G = (f + i ) / r approx. = 1, combined with the strong resonance line are consistent with a dense, collision-dominated plasma. Both the RGS and EPIC/MOS spectra are well fit by emission horn an optically thin thermal plasma with an emission measure (EM) is a member of (kT/6.5 keV)(sup 0.8) (model cevmkl in XSPEC). Helium, nitrogen, oxygen and neon are required to adequately model the spectrum, however, the inclusion of sulphur and iron further improves the fit, suggesting these elements may also be present at low abundance. We confirm in the X-rays the under- abundance of both carbon and oxygen relative to nitrogen, first deduced from optical spectroscopy by Marsh et al. The average X-ray luminosity of approx. = 3 x 10(exp 30) ergs/s implies a mass accretion rate dot-m approx. = 9 x 10(exp -13) solar mass/yr. The implied temperature and density of the emitting plasma, combined with the presence of narrow emission lines and the low dot-m value, are consistent with production of the X-ray emission in an optically thin boundary layer just above the surface of the white dwarf.

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

    Science.gov (United States)

    Cheung, G.; Hooker, S. M.

    2016-08-01

    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.

  3. The High Energy X-ray Spectrum of 4U1700-37 Observed from OSO-8

    Science.gov (United States)

    Dolan, J. F.; Coe, M. J.; Crannell, C. J.; Dennis, B. R.; Frost, K. J.; Maurer, G. S.; Orwig, L. E.

    1979-01-01

    The most intense hard X-ray source in the confused region in Scorpius is identified as 4U1700-37. The 3.4-day modulation is seen above 20 keV with the intensity during eclipse being consistent with zero flux. The photon-number spectrum from 20 to 150 keV is well represented by a single power law with a photo-number spectral index of -2.77 + or - 0.35 or by a thermal bremsstrahlung spectrum with kT = 27 96.8-min X-ray modulation previously reported at lower energies. Despite the difficulties in reconciling both the lack of periodic modulation in the emitted X-radiation and the orbital dynamics of the system with theories of the evolution and physical properties of neutron stars, the observed properties of 4U1700-37 are all consistent with the source being a spherically accreting neutron star rather than a black hole.

  4. Astrophysical Fluids of Novae: High Resolution Pre-decay X-ray spectrum of V4743 Sagittarii

    CERN Document Server

    Ramírez-Velasquez, J M

    2016-01-01

    Eight X-ray observations of V4743 Sgr (2002), observed with Chandra and XMM-Newton are presented. The nova turned off some time between days 301.9 and 371, and the X-ray flux subsequently decreased from day 301.9 to 526 following an exponential decline time scale of $(96 \\pm 3)$ days. We use the absorption lines present in the SSS spectrum for diagnostic purposes, and characterize the physics and the dynamics of the expanding atmosphere during the explosion of the nova. The information extracted from this first stage is then used as input for computing full photoionization models of the ejecta in V4743 Sgr. The SSS spectrum is modeled with a simple black-body and multiplicative Gaussian lines, which provides us of a general kinematical picture of the system, before it decays to its faint phase (Ness et al. 2003). In the grating spectra taken between days 180.4 and 370, we can resolve the line profiles of absorption lines arising from H-like and He-like C, N, and O, including transitions involving higher princ...

  5. The Soft X-Ray Variability and Spectrum of 1H0419-577 from a Long EUVE Observation

    Science.gov (United States)

    Marshall, H. L.; Halpern, J. P.; Leighly, K.

    1999-01-01

    The active galaxy associated with the hard X-ray source 1H0419-577 was observed with EUVE (Extreme Ultraviolet Explorer Satellite) for about 25 days to obtain a long, contiguous light curve and an EUV spectrum. An EUV source was detected which was about as bright as the AGN (Active Galactic Nuclei) and was later identified as an AM Her type system. The AGN showed variations as large as a factor of two over 5-10 day time scales and occasionally varied by 20-30% in less than 0.5day. The spectrum is dominated by a continuum that is poorly fit by a simple power law. There are possible emission lines without positive identifications but the lines are likely to be spurious.

  6. Broad-band spectral analysis of the accreting millisecond X-ray pulsar SAX J1748.9-2021

    Science.gov (United States)

    Pintore, F.; Sanna, A.; Di Salvo, T.; Del Santo, M.; Riggio, A.; D'Aì, A.; Burderi, L.; Scarano, F.; Iaria, R.

    2016-04-01

    We analysed a 115-ks XMM-Newton observation and the stacking of 8 d of INTEGRAL observations, taken during the raise of the 2015 outburst of the accreting millisecond X-ray pulsar SAX J1748.9-2021. The source showed numerous type-I burst episodes during the XMM-Newton observation, and for this reason we studied separately the persistent and burst epochs. We described the persistent emission with a combination of two soft thermal components, a cold thermal Comptonization component (˜2 keV) and an additional hard X-ray emission described by a power law (Γ ˜ 2.3). The continuum components can be associated with an accretion disc, the neutron star (NS) surface and a thermal Comptonization emission coming out of an optically thick plasma region, while the origin of the high-energy tail is still under debate. In addition, a number of broad (σ = 0.1-0.4 keV) emission features likely associated with reflection processes have been observed in the XMM-Newton data. The estimated 1.0-50 keV unabsorbed luminosity of the source is ˜5 × 1037 erg s-1, about 25 per cent of the Eddington limit assuming a 1.4 M⊙ NS. We suggest that the spectral properties of SAX J1748.9-2021 are consistent with a soft state, differently from many other accreting X-ray millisecond pulsars which are usually found in the hard state. Moreover, none of the observed type-I burst reached the Eddington luminosity. Assuming that the burst ignition and emission are produced above the whole NS surface, we estimate an NS radius of ˜7-8 km, consistent with previous results.

  7. A W:B4C multilayer phase retarder for broadband polarization analysis of soft x-ray radiation

    OpenAIRE

    MacDonald, Michael A.; Schaefers, Franz; Pohl, R.; Poole, Ian B.; Gaupp, Andreas; Quinn, Frances M.

    2008-01-01

    A W:B4C multilayer phase retarder has been designed and characterized which shows a nearly constant phase retardance between 640 and 850 eV photon energies when operated near the Bragg condition. This freestanding transmission multilayer was used successfully to determine, for the first time, the full polarization vector at soft x-ray energies above 600 eV, which was not possible before due to the lack of suitable optical elements. Thus, quantitative polarimetry is now possible at the 2p edge...

  8. Broad-band spectral analysis of the accreting millisecond X-ray pulsar SAX J1748.9-2021

    CERN Document Server

    Pintore, Fabio; Di Salvo, Tiziana; Del Santo, Melania; Riggio, Alessandro; D'Aì, Antonino; Burderi, Luciano; Scarano, Fabiana; Iaria, Rosario

    2016-01-01

    We analyzed a 115 ks XMM-Newton observation and the stacking of 8 days of INTEGRAL observations, taken during the raise of the 2015 outburst of the accreting millisecond X-ray pulsar SAX J1748.9-2021. The source showed numerous type-I burst episodes during the XMM-Newton observation, and for this reason we studied separately the persistent and burst epochs. We described the persistent emission with a combination of two soft thermal components, a cold thermal Comptonization component (~2 keV) and an additional hard X-ray emission described by a power-law (photon index ~2.3). The continuum components can be associated with an accretion disc, the neutron star (NS) surface and a thermal Comptonization emission coming out of an optically thick plasma region, while the origin of the high energy tail is still under debate. In addition, a number of broad (~0.1-0.4 keV) emission features likely associated to reflection processes have been observed in the XMM-Newton data. The estimated 1.0-50 keV unabsorbed luminosity ...

  9. X-ray photoemission spectrum, electronic structure, and magnetism of UCu{sub x}Sb{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Samsel-Czekała, M., E-mail: M.Samsel@int.pan.wroc.pl [W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wrocław 2 (Poland); Talik, E. [A. Chełkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Winiarski, M.J.; Troć, R. [W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wrocław 2 (Poland)

    2015-07-25

    Highlights: • Electronic structure of UCu{sub x}Sb{sub 2} probed by X-ray photoemission (XPS) and ab initio. • Good agreement between experimental and calculated (x = 0.75) XPS valence spectra. • Good accord between experimental and calculated ferromagnetic moments on U atoms. • Complex experimental core-level XPS spectrum with three: 1-, 3- and 7-eV satellites. • Concluded dual and mixed-valence configuration of U 5f states in UCu{sub 0.83}Sb{sub 2}. - Abstract: The room temperature valence and core-level X-ray photoemission spectra of an UCu{sub 0.83}Sb{sub 2} single crystal were measured using the Al Kα source. The related theoretical valence spectra were determined from densities of states for UCu{sub x}Sb{sub 2} systems obtained from our band structure calculations using the FLAPW method in the LDA + U approximation, as implemented in the Wien2k code, and the supercell approach to simulate a deficit of the Cu atoms. The calculated spectrum of the Cu-deficit UCu{sub 0.75}Sb{sub 2} is in good accord with the experimental one, revealing a complete localization of the Cu 3d electrons and a dual (both localized and itinerant) behavior as well as unusual spin-up polarization of the U 5f states near the Fermi level. Our calculated total magnetic moments on the uranium atom are in reasonable agreement with the experimental value of magnetization. Some localization and valence-mixing of the 5f-electrons are reflected by the triple-satellite (sats. 1-eV, 3-eV and 7-eV) structure, visible in the spectrum of the U 4f core-lines. Also the calculated Fermi surface of the stoichiometric system is complex, containing five spin-polarized sheets of different dimensionality with some nesting features.

  10. Structure of the sulfur K x-ray emission spectrum: influence of the oxidation state

    Science.gov (United States)

    Pérez, P. D.; Carreras, A. C.; Trincavelli, J. C.

    2012-01-01

    The sulfur K x-ray emission was studied in pure sulfur, anhydrite (CaSO4) and sphalerite (ZnS) samples. The ionizations were induced by electron impact and the spectra were recorded with a wavelength dispersive spectrometer. The spectral processing was performed through a methodology based on the optimization of atomic and experimental parameters. Energies and intensities of diagram and satellite lines were determined for a set of transitions in the Kα and Kβ groups. The lines studied include Kα22, Kα2, Kα1, Kα‧, Kα3, Kα4, Kα5, Kα6, Kβ1,3, Kβ-RAE, KβIII, KβIV, Kβx, Kβ‧ and Kβ″. The main spectral differences between the three oxidation states were analysed, considering the influence of the ligand atoms. The results were compared with data published by other authors and the origin of certain lines was discussed on the basis of data available in the literature.

  11. A Photoionization Model For The Soft X-Ray Spectrum Of NGC 4151

    CERN Document Server

    Armentrout, B K; Turner, T J

    2007-01-01

    We present analysis of archival data from multiple XMM-Newton observations of the Seyfert 1 galaxy NGC 4151. Spectral data from the RGS instruments reveal several strong soft X-ray emission lines, chiefly from hydrogen-like and helium-like oxygen, nitrogen, neon and carbon. Radiative recombination continua (RRC) from oxygen and carbon are also detected. Our analysis suggests that the emission data are consistent with photoionization. Using the CLOUDY photoionization code, we found that, while a two-component, high column density model (10e23 cm-2) with low covering factor proved adequate in reproducing all detected Lyman series lines, it proved insufficient in modeling He-like triplets observed (neon, oxygen, and nitrogen). If resonance line data were ignored, the two-component model was sufficient to match flux from intercombination and forbidden lines. However, with the inclusion of resonance line data, He-like triplets could no longer be modeled with only two components. We found that observed oxygen G and...

  12. X-rays spectrum and air Kerma during a mammography study

    International Nuclear Information System (INIS)

    In this calculation series was modeled the source of electrons, the target and the filter. Using thermoluminescent dosemeters of ZrO2+PTFE the air Kerma was measured in five points located on a phantom made with acrylic and water when it was exposed to a X-rays beam produced by electrons of 24 KeV and 10 m A of current that produces a mammography. The air Kerma values at the entrance surface of the phantom were compared with values calculated by Monte Carlo methods. The air Kerma values measured indicate that approximately the five points receive the same air Kerma, what means that the beam is homogeneous, of the Monte Carlo calculations we find that the center receives a greater dose what implies that the beam is not uniform, the explanation of this fact is attributed to was used a simple model in the calculations, nevertheless, the air Kerma average measured at the entrance surface of the phantom was of 0.96 +- 0.03 m G, while the other obtained by the calculations was of 0.96 +- 0.06 mGy, to compare both do not exist significant differences. (author)

  13. Experimental evaluation of the image quality and dose in digital mammography: Influence of x-ray spectrum

    Science.gov (United States)

    Tomal, A.; Perez, A. M. M. M.; Silva, M. C.; Poletti, M. E.

    2015-11-01

    In this work, we studied experimentally the influence of x-ray spectrum on the contrast-to-noise ratio (CNR) and the average glandular dose (MDG) for two digital mammography systems: Senographe 2000D (GE Medical Systems) and Lorad Selenia (Hologic), with indirect and direct detector imaging technology, respectively. CNR and MGD were determined using PMMA phantoms simulating breasts with thicknesses of 4 cm and 6 cm. All available anode/filter combinations of the systems were evaluated for a wide range of tube voltages values. Results indicated that the Rh/Rh combination provides the highest image quality with the lower mean glandular dose for the Senographe 2000D system. For the Lorad Selenia system, the W/Ag combination at 30 kV showed the best performance, in terms of dose saving and image quality improvement in relation to all tube voltage range. The comparison between the optimal x-ray spectra and those selected by the AEC mode showed that this automatic selection mechanism could be readjusted to optimize the relationship between image quality and dose.

  14. Detection of Nitrogen and Neon in the X-ray Spectrum of GP Com with XMM/Newton

    CERN Document Server

    Strohmayer, T E

    2004-01-01

    We report on X-ray spectroscopic observations with XMM/Newton of the ultracompact, double white dwarf binary, GP Com. With the Reflection Grating Spectrometers (RGS) we detect the Lyman alpha and beta lines of hydrogen-like nitrogen (N VII) and neon (Ne X), as well as the helium-like triplets (N VI and Ne IX) of these same elements. All the emission lines are unresolved. These are the first detections of X-ray emission lines from a double-degenerate, AM CVn system. We detect the resonance (r) and intercombination (i) lines of the N VI triplet, but not the forbidden (f) line. The implied line ratios for N VI, R = f/i < 0.3, and G = (f + i)/r ~1, combined with the strong resonance line are consistent with formation in a dense, collision-dominated plasma. Both the RGS and EPIC/MOS spectra are well fit by emission from an optically thin thermal plasma (model cevmkl in XSPEC). Helium, nitrogen, oxygen and neon are required to adequately model the spectrum, however, the inclusion of sulphur and iron further impr...

  15. A Compton-thin Solution for the Suzaku X-ray Spectrum of the Seyfert 2 Galaxy Mkn 3

    CERN Document Server

    Yaqoob, T; Scholtes, A; Gottlieb, A; Turner, T J

    2015-01-01

    Mkn 3 is a Seyfert 2 galaxy that is widely regarded as an exemplary Compton-thick AGN. We study the Suzaku X-ray spectrum using models of the X-ray reprocessor that self-consistently account for the Fe K$\\alpha$ fluorescent emission line and the associated Compton-scattered, or reflection, continuum. We find a solution in which the average global column density, $0.234^{+0.012}_{-0.010} \\times 10^{24} \\ \\rm cm^{-2}$, is very different to the line-of-sight column density, $0.902^{+0.012}_{-0.013} \\times 10^{24} \\ \\rm cm^{-2}$. The global column density is $\\sim 5$ times smaller than that required for the matter distribution to be Compton-thick. Our model accounts for the profiles of the Fe K$\\alpha$ and Fe K$\\beta$ lines, and the Fe K edge remarkably well, with a solar abundance of Fe. The matter distribution could consist of a clumpy medium with a line-of-sight column density higher than the global average. A uniform, spherically-symmetric distribution alone cannot simultaneously produce the correct fluoresce...

  16. NuSTAR and XMM-Newton Observations of the Hard X-Ray Spectrum of Centaurus A

    CERN Document Server

    Fuerst, F; Madsen, K K; Lanz, L; Rivers, E; Brightman, M; Arevalo, P; Balokovic, M; Beuchert, T; Boggs, S E; Christensen, F E; Craig, W W; Dauser, T; Farrah, D; Graefe, C; Hailey, C J; Harrison, F A; Kadler, M; King, A; Krauss, F; Madejski, G; Matt, G; Marinucci, A; Markowitz, A; Ogle, P; Ojha, R; Rothschild, R; Stern, D; Walton, D J; Wilms, J; Zhang, W

    2015-01-01

    We present simultaneous XMM-Newton and NuSTAR observations spanning 3-78 keV of the nearest radio galaxy, Centaurus A (Cen A), performed during a very high flux state. The accretion geometry around the central engine in Cen A is still debated, and we investigate possible configurations using detailed X-ray spectral modeling. NuSTAR imaged the central region of Cen A with subarcminute resolution at X-ray energies above 10 keV for the first time, but finds no evidence for an extended source or other off-nuclear point-sources. The XMM-Newton and NuSTAR spectra agree well and can be described with an absorbed power-law with a photon index {\\Gamma} = 1.815 +/- 0.005 and a fluorescent Fe K{\\alpha} line in good agreement with literature values. The spectrum does not require a high-energy exponential rollover, with a constraint of E_fold > 1MeV. A thermal Comptonization continuum describes the data well, with parameters that agree with values measured by INTEGRAL, in particular an electron temperature of kT_e ~ 220 k...

  17. NuSTAR and XMM-Newton Observations of the Hard X-Ray Spectrum of Centaurus A

    DEFF Research Database (Denmark)

    Fürst, F.; Müller, C.; Madsen, K. K.;

    2016-01-01

    We present simultaneous XMM-Newton and NuSTAR observations spanning 3–78 keV of the nearest radiogalaxy, Centaurus A (Cen A), performed during a very high flux state. The accretion geometry around thecentral engine in Cen A is still debated, and we investigate possible configurations using detailed...... X-ray spectralmodeling. NuSTAR imaged the central region of Cen A with subarcminute resolution at X-ray energies above10 keV for the first time, but finds no evidence for an extended source or other off-nuclear point-sources.The XMM-Newton and NuSTAR spectra agree well and can be described with an...... absorbed power-law witha photon index Γ = 1.815 ± 0.005 and a fluorescent Fe Kα line in good agreement with literature values.The spectrum does not require a high-energy exponential rollover, with a constraint of Efold > 1 MeV. Athermal Comptonization continuum describes the data well, with parameters that...

  18. 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,...

  19. Connections between the Radio, Optical and Soft X-ray Luminosities for Flat-Spectrum Radio Quasars

    Indian Academy of Sciences (India)

    Zhi-Fu Chen; Cai-Juan Pan; You-Bing Li; Yu-Tao Zhou

    2014-09-01

    We investigate the connections between radio, optical and soft X-ray luminosities with a sample of 538 FSRQs. We find that the radio luminosity is strongly correlated with the optical luminosity, as well as with the soft X-ray luminosity. We also find that the optical luminosity is strongly correlated with the soft X-ray luminosity.

  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 NuSTAR...... 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....

  1. Toxicity modulation, resistance enzyme evasion, and A-site X-ray structure of broad-spectrum antibacterial neomycin analogs.

    Science.gov (United States)

    Maianti, Juan Pablo; Kanazawa, Hiroki; Dozzo, Paola; Matias, Rowena D; Feeney, Lee Ann; Armstrong, Eliana S; Hildebrandt, Darin J; Kane, Timothy R; Gliedt, Micah J; Goldblum, Adam A; Linsell, Martin S; Aggen, James B; Kondo, Jiro; Hanessian, Stephen

    2014-09-19

    Aminoglycoside antibiotics are pseudosaccharides decorated with ammonium groups that are critical for their potent broad-spectrum antibacterial activity. Despite over three decades of speculation whether or not modulation of pKa is a viable strategy to curtail aminoglycoside kidney toxicity, there is a lack of methods to systematically probe amine-RNA interactions and resultant cytotoxicity trends. This study reports the first series of potent aminoglycoside antibiotics harboring fluorinated N1-hydroxyaminobutyryl acyl (HABA) appendages for which fluorine-RNA contacts are revealed through an X-ray cocrystal structure within the RNA A-site. Cytotoxicity in kidney-derived cells was significantly reduced for the derivative featuring our novel β,β-difluoro-HABA group, which masks one net charge by lowering the pKa without compromising antibacterial potency. This novel side-chain assists in evasion of aminoglycoside-modifying enzymes, and it can be easily transferred to impart these properties onto any number of novel analogs.

  2. Variation of focal switch with spectrum of a broadband laser

    Science.gov (United States)

    Zhang, Biyu; Peng, Runwu; Xie, Haiqing; Zhang, Wei

    2016-05-01

    Effects of the spectrum on focal switch of a broadband laser in a dispersion dual-focus system are presented in this paper. The numerical results show that the two maximum intensities of the broadband laser on the z-axis vary when the central frequency of the broadband laser shifts and the spectrum shape changes, and the variations affect the generation of the focal switch. It is also found that difference of the two maximum intensities tends to increase when the absolute value of central wavelength increases. According to the results in this paper, the generation of the focal switch can be controlled by choosing the shift of the central frequency, the bandwidth, the distance between the two lenses, and the spectrum shape of the broadband laser.

  3. The origin of blueshifted absorption features in the X-ray spectrum of PG 1211+143: outflow or disc

    Science.gov (United States)

    Gallo, L. C.; Fabian, A. C.

    2013-07-01

    In some radio-quiet active galactic nuclei (AGN), high-energy absorption features in the X-ray spectra have been interpreted as ultrafast outflows (UFOs) - highly ionized material (e.g. Fe XXV and Fe XXVI) ejected at mildly relativistic velocities. In some cases, these outflows can carry energy in excess of the binding energy of the host galaxy. Needless to say, these features demand our attention as they are strong signatures of AGN feedback and will influence galaxy evolution. For the same reason, alternative models need to be discussed and refuted or confirmed. Gallo and Fabian proposed that some of these features could arise from resonance absorption of the reflected spectrum in a layer of ionized material located above and corotating with the accretion disc. Therefore, the absorbing medium would be subjected to similar blurring effects as seen in the disc. A priori, the existence of such plasma above the disc is as plausible as a fast wind. In this work, we highlight the ambiguity by demonstrating that the absorption model can describe the ˜7.6 keV absorption feature (and possibly other features) in the quasar PG 1211+143, an AGN that is often described as a classic example of a UFO. In this model, the 2-10 keV spectrum would be largely reflection dominated (as opposed to power law dominated in the wind models) and the resonance absorption would be originating in a layer between about 6 and 60 gravitational radii. The studies of such features constitute a cornerstone for future X-ray observatories like Astro-H and Athena+. Should our model prove correct, or at least important in some cases, then absorption will provide another diagnostic tool with which to probe the inner accretion flow with future missions.

  4. 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.

  5. Detection of a high frequency break in the X-ray power spectrum of Ark 564

    CERN Document Server

    Papadakis, I E; Negoro, H; Gliozzi, M

    2001-01-01

    We present a power spectrum analysis of the long ASCA observation of Ark 564 in June/July 2001. The observed power spectrum covers a frequency range of ~ 3.5 decades. We detect a high frequency break at ~ 0.002 Hz. The power spectrum has an rms of ~30% and a slope of ~ -1 and ~ -2 below and above the break frequency. When combined with the results from a long RXTE observation (Pounds et al. 2001), the observed power spectra of Ark 564 and Cyg X-1 (in the low/hard state) are almost identical, showing a similar shape and rms amplitude. However, the ratio of the high frequency breaks is very small (~ 10e{3-4}), implying that these characteristic frequencies are not indicative of the black hole mass. This result supports the idea of a small black hole mass/high accretion rate in Ark 564.

  6. Inverse problem in Ionospheric Science: Prediction of solar soft-X-ray spectrum from Very Low Frequency Radiosonde results

    CERN Document Server

    Palit, Sourav; Chakrabarti, Sandip K

    2015-01-01

    X-rays and gamma-rays from astronomical sources such as solar flares are mostly absorbed by the Earth's atmosphere. Resulting electron-ion production rate as a function of height depends on the intensity and wavelength of the injected spectrum and therefore the effects vary from one source to another. In other words, the ion density vs. altitude profile has the imprint of the incident photon spectrum. In this paper, we investigate whether we can invert the problem uniquely by deconvolution of the VLF amplitude signal to obtain the details of the injected spectrum. We find that it is possible to do this up to a certain accuracy. Our method is useful to carry out a similar exercise to infer the spectra of more energetic events such as the Gamma Ray Bursts (GRBs), Soft Gamma Ray Repeaters (SGRs) etc. by probing even the lower part of the atmosphere. We thus show that to certain extent, the Earth's atmosphere could be used as a gigantic detector of relatively strong events.

  7. First Limits on the 21 cm Power Spectrum during the Epoch of X-ray heating.

    Science.gov (United States)

    Ewall-Wice, A.; Dillon, Joshua S.; Hewitt, J. N.; Loeb, A.; Mesinger, A.; Neben, A. R.; Offringa, A. R.; Tegmark, M.; Barry, N.; Beardsley, A. P.; Bernardi, G.; Bowman, Judd D.; Briggs, F.; Cappallo, R. J.; Carroll, P.; Corey, B. E.; de Oliveira-Costa, A.; Emrich, D.; Feng, L.; Gaensler, B. M.; Goeke, R.; Greenhill, L. J.; Hazelton, B. J.; Hurley-Walker, N.; Johnston-Hollitt, M.; Jacobs, Daniel C.; Kaplan, D. L.; Kasper, J. C.; Kim, HS; Kratzenberg, E.; Lenc, E.; Line, J.; Lonsdale, C. J.; Lynch, M. J.; McKinley, B.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Thyagarajan, Nithyanandan; Oberoi, D.; Ord, S. M.; Paul, S.; Pindor, B.; Pober, J. C.; Prabu, T.; Procopio, P.; Riding, J.; Rogers, A. E. E.; Roshi, A.; Shankar, N. Udaya; Sethi, Shiv K.; Srivani, K. S.; Subrahmanyan, R.; Sullivan, I. S.; Tingay, S. J.; Trott, C. M.; Waterson, M.; Wayth, R. B.; Webster, R. L.; Whitney, A. R.; Williams, A.; Williams, C. L.; Wu, C.; Wyithe, J. S. B.

    2016-05-01

    We present first results from radio observations with the Murchison Widefield Array seeking to constrain the power spectrum of 21 cm brightness temperature fluctuations between the redshifts of 11.6 and 17.9 (113 and 75 MHz). Three hours of observations were conducted over two nights with significantly different levels of ionospheric activity. We use these data to assess the impact of systematic errors at low frequency, including the ionosphere and radio-frequency interference, on a power spectrum measurement. We find that after the 1-3 hours of integration presented here, our measurements at the Murchison Radio Observatory are not limited by RFI, even within the FM band, and that the ionosphere does not appear to affect the level of power in the modes that we expect to be sensitive to cosmology. Power spectrum detections, inconsistent with noise, due to fine spectral structure imprinted on the foregrounds by reflections in the signal-chain, occupy the spatial Fourier modes where we would otherwise be most sensitive to the cosmological signal. We are able to reduce this contamination using calibration solutions derived from autocorrelations so that we achieve an sensitivity of 104 mK on comoving scales k ≲ 0.5 hMpc-1. This represents the first upper limits on the 21 cm power spectrum fluctuations at redshifts 12 ≲ z ≲ 18 but is still limited by calibration systematics. While calibration improvements may allow us to further remove this contamination, our results emphasize that future experiments should consider carefully the existence of and their ability to calibrate out any spectral structure within the EoR window.

  8. First limits on the 21 cm power spectrum during the Epoch of X-ray heating

    Science.gov (United States)

    Ewall-Wice, A.; Dillon, Joshua S.; Hewitt, J. N.; Loeb, A.; Mesinger, A.; Neben, A. R.; Offringa, A. R.; Tegmark, M.; Barry, N.; Beardsley, A. P.; Bernardi, G.; Bowman, Judd D.; Briggs, F.; Cappallo, R. J.; Carroll, P.; Corey, B. E.; de Oliveira-Costa, A.; Emrich, D.; Feng, L.; Gaensler, B. M.; Goeke, R.; Greenhill, L. J.; Hazelton, B. J.; Hurley-Walker, N.; Johnston-Hollitt, M.; Jacobs, Daniel C.; Kaplan, D. L.; Kasper, J. C.; Kim, HS; Kratzenberg, E.; Lenc, E.; Line, J.; Lonsdale, C. J.; Lynch, M. J.; McKinley, B.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Thyagarajan, Nithyanandan; Oberoi, D.; Ord, S. M.; Paul, S.; Pindor, B.; Pober, J. C.; Prabu, T.; Procopio, P.; Riding, J.; Rogers, A. E. E.; Roshi, A.; Shankar, N. Udaya; Sethi, Shiv K.; Srivani, K. S.; Subrahmanyan, R.; Sullivan, I. S.; Tingay, S. J.; Trott, C. M.; Waterson, M.; Wayth, R. B.; Webster, R. L.; Whitney, A. R.; Williams, A.; Williams, C. L.; Wu, C.; Wyithe, J. S. B.

    2016-08-01

    We present first results from radio observations with the Murchison Widefield Array seeking to constrain the power spectrum of 21 cm brightness temperature fluctuations between the redshifts of 11.6 and 17.9 (113 and 75 MHz). 3 h of observations were conducted over two nights with significantly different levels of ionospheric activity. We use these data to assess the impact of systematic errors at low frequency, including the ionosphere and radio-frequency interference, on a power spectrum measurement. We find that after the 1-3 h of integration presented here, our measurements at the Murchison Radio Observatory are not limited by RFI, even within the FM band, and that the ionosphere does not appear to affect the level of power in the modes that we expect to be sensitive to cosmology. Power spectrum detections, inconsistent with noise, due to fine spectral structure imprinted on the foregrounds by reflections in the signal-chain, occupy the spatial Fourier modes where we would otherwise be most sensitive to the cosmological signal. We are able to reduce this contamination using calibration solutions derived from autocorrelations so that we achieve an sensitivity of 104 mK on comoving scales k ≲ 0.5 h Mpc-1. This represents the first upper limits on the 21 cm power spectrum fluctuations at redshifts 12 ≲ z ≲ 18 but is still limited by calibration systematics. While calibration improvements may allow us to further remove this contamination, our results emphasize that future experiments should consider carefully the existence of and their ability to calibrate out any spectral structure within the EoR window.

  9. The Remarkably Featureless High Resolution X-ray Spectrum of Mrk 478

    CERN Document Server

    Marshall, H L; Vaughan, S; Malkan, M A; O'Brien, P T; Warwick, R; Marshall, Herman L.; Edelson, Rick A.; Vaughan, Simon; Malkan, Mathew A.; Brien, Paul O'; Warwick, Robert

    2002-01-01

    An observation of Mrk 478 using the Chandra Low Energy Transmission Grating Spectrometer is presented. The source exhibited 30-40% flux variations on timescales of order 10000 s together with a slow decline in the spectral softness over the full 80 ks observation. The 0.15--3.0 keV spectrum is well fitted by a single power law with photon index of Gamma = 2.91 +/- 0.03. Combined with high energy data from BeppoSAX, the spectrum from 0.15 to 10 keV is well fit as the sum of two power laws with Gamma = 3.03 +/- 0.04, which dominates below 2 keV and 1.4 +/- 0.2, which dominates above 2 keV (quoting 90% confidence uncertainties). No significant emission or absorption features are detected in the high resolution spectrum, supporting our previous findings using the Extreme Ultraviolet Explorer but contradicting the claims of emission lines by Hwang & Bowyer (1997). There is no evidence of a warm absorber, as found in the high resolution spectra of many Sy 1 galaxies including others classified as narrow line Sy...

  10. First Limits on the 21 cm Power Spectrum during the Epoch of X-ray heating

    CERN Document Server

    Ewall-Wice, A; Hewitt, J N; Loeb, A; Mesinger, A; Neben, A R; Offringa, A R; Tegmark, M; Barry, N; Beardsley, A P; Bernardi, G; Bowman, Judd D; Briggs, F; Cappallo, R J; Carroll, P; Corey, B E; de Oliveira-Costa, A; Emrich, D; Feng, L; Gaensler, B M; Goeke, R; Greenhill, L J; Hazelton, B J; Hurley-Walker, N; Johnston-Hollit, M; Jacobs, Daniel C; Kaplan, D L; Kasper, J C; Kim, HS; Kratzenberg, E; Lenc, E; Line, J; Lonsdale, C J; Lynch, M J; McKinley, B; McWhirter, S R; Mitchell, D A; Morales, M F; Morgan, E; Thyagarajan, Nithyanandan; Oberoi, D; Ord, S M; Paul, S; Pindor, B; Pober, J C; Prabu, T; Procopio, P; Riding, J; Rogers, A E E; Roshi, A; Shankar, N Udaya; Sethi, Shiv K; Srivani, K S; Subrahmanyan, R; Sullivan, I S; Tingay, S J; Trott, C M; Waterson, M; Wayth, R B; Webster, R L; Whitney, A R; Williams, A; Williams, C L; Wu, C; Wyithe, J S B

    2016-01-01

    We present first results from radio observations with the Murchison Widefield Array seeking to constrain the power spectrum of 21 cm brightness temperature fluctuations between the redshifts of 11.6 and 17.9 (113 and 75 MHz). Three hours of observations were conducted over two nights with significantly different levels of ionospheric activity. We use these data to assess the impact of systematic errors at low frequency, including the ionosphere and radio-frequency interference, on a power spectrum measurement. We find that after the 1-3 hours of integration presented here, our measurements at the Murchison Radio Observatory are not limited by RFI, even within the FM band, and that the ionosphere does not appear to affect the level of power in the modes that we expect to be sensitive to cosmology. Power spectrum detections, inconsistent with noise, due to fine spectral structure imprinted on the foregrounds by reflections in the signal-chain, occupy the spatial Fourier modes where we would otherwise be most se...

  11. Sensitivity Analysis Applied to Atomic Data Used for X-ray Spectrum Synthesis

    Science.gov (United States)

    Kallman, T.

    2006-01-01

    A great deal of work has been devoted to the accumulation of accurate quantities describing atomic processes for use in analysis of astrophysical spectra. But in many situations of interest the interpretation of a quantity which is observed, such as a line flux, depends on the results of a modeling- or spectrum synthesis code. The results of such a code depends in turn on many atomic rates or cross sections, and the sensitivity of the observable quantity on the various rates and cross sections may be non-linear and if so cannot easily be derived analytically. This talk describes simple numerical experiments designed to examine some of these issues.

  12. Atomic Data for X-ray Spectrum Synthesis: Sensitivity Analysis and Consequences for Spectral Fitting

    Science.gov (United States)

    Kallman, Timothy R.

    2006-09-01

    A great deal of work has been devoted to the accumulation of accurate quantities describing atomic processes for use in analysis of astrophysical spectra. But in many situations of interest the interpretation of a quantity which is observed, such as a line flux, depends on the results of a modeling- or spectrum synthesis code. The results of such a code depends in turn on many atomic rates or cross sections, and the sensitivity of the observable quantity on the various rates and cross sections may be non-linear and if so cannot easily be derived analytically. In such cases the most practical approach to understanding the sensitivity of observables to atomic cross sections is to perform numerical experiments, by calculating models with various rates perturbed by random (but known) factors. In addition, it is useful to compare the results of such experiments with some sample observations, in order to focus attention on the rates which are of the greatest relevance to real observations. I will present some attempts to carry out this program, focussing on two sample datasets taken with the Chandra HETG. I will discuss the sensitivity of synthetic spectra to atomic data affecting ionization balance, temperature, and line opacity or emissivity, and discuss the implications for the ultimate goal of inferring astrophysical parameters. In addition, I will discuss the likely effects on the ionization balance and spectrum synthesis due to the adoption of some recent calculations of dielectronic recombination rate coefficients.

  13. Modelling the Extreme X-ray Spectrum of IRAS 13224-3809

    CERN Document Server

    Chiang, Chia-Ying; Fabian, A C; Wilkins, D R; Gallo, L C

    2014-01-01

    The extreme NLS1 galaxy IRAS 13224-3809 shows significant variability, frequency depended time lags, and strong Fe K line and Fe L features in the long 2011 XMM-Newton observation. In this work we study the spectral properties of IRAS 13224-3809 in detail, and carry out a series of analyses to probe the nature of the source, focusing in particular on the spectral variability exhibited. The RGS spectrum shows no obvious signatures of absorption by partially ionised material (warm absorbers). We fit the 0.3-10.0 keV spectra with a model that includes relativistic reflection from the inner accretion disc, a standard powerlaw AGN continuum, and a low-temperature (~0.1 keV) blackbody, which may originate in the accretion disc, either as direct or reprocessed thermal emission. We find that the reflection model explains the time-averaged spectrum well, and we also undertake flux-resolved and time-resolved spectral analyses, which provide evidence of gravitational light-bending effects. Additionally, the temperature ...

  14. The effects of high density on the X-ray spectrum reflected from accretion discs around black holes

    Science.gov (United States)

    García, Javier A.; Fabian, Andrew C.; Kallman, Timothy R.; Dauser, Thomas; Parker, Michael L.; McClintock, Jeffrey E.; Steiner, James F.; Wilms, Jörn

    2016-10-01

    Current models of the spectrum of X-rays reflected from accretion discs around black holes and other compact objects are commonly calculated assuming that the density of the disc atmosphere is constant within several Thomson depths from the irradiated surface. An important simplifying assumption of these models is that the ionization structure of the gas is completely specified by a single, fixed value of the ionization parameter ξ, which is the ratio of the incident flux to the gas density. The density is typically fixed at ne = 1015 cm-3. Motivated by observations, we consider higher densities in the calculation of the reflected spectrum. We show by computing model spectra for ne ≳ 1017 cm-3 that high-density effects significantly modify reflection spectra. The main effect is to boost the thermal continuum at energies ≲ 2 keV. We discuss the implications of these results for interpreting observations of both active galactic nuclei and black hole binaries. We also discuss the limitations of our models imposed by the quality of the atomic data currently available.

  15. The 0.1-2.5-KEV X-Ray Spectrum of the O4F-STAR Zeta-Puppis

    Science.gov (United States)

    Hillier, D. J.; Kudritzki, R. P.; Pauldrach, A. W.; Baade, D.; Cassinelli, J. P.; Puls, J.; Schmitt, J. H. M. M.

    1993-09-01

    We have obtained a high quality ROSAT PSPC spectrum of the bright O4f star ζ Pup. Allowing for the wind X-ray opacity, as computed from detailed non-LTE stellar wind models of ζ Pup, and under the assumption that the X-rays arise from shocks distributed throughout the wind, we have been able to match the observed X-ray spectrum (0.1 to 2.5keV). The best model fit is obtained when He++ recombines to He+ in the outer regions of the stellar wind, as predicted by recent detailed cool wind model calculations. With a single temperature plasma, the best model fit indicates a temperature of log Ts(K) = 6.5 to 6.6 corresponding to shock velocities of around 500 km s-1. A 2 temperature plasma yields a significantly improved fit, and indicates temperatures of log Ts(K) = 6.2 and 6.7 for the 2 components. The hotter component accounts for 55% of the intrinsic (75% of the observed) X-ray flux. Due to absorption by the stellar wind, and to a minor extent stellar occultation, less than 5% of the total emitted X-ray flux escapes the star. The models require significant X-ray emission (particularly at energies less than 0.5 keV) from large radii (r > 100R*). In models without recombination, the fits, even with a 2 temperature plasma, are unacceptable. A significant K shell absorption is predicted by these models, but is definitely not present in the observational data. The analysis suggests that the X-ray flux provides an invaluable diagnostic of the ionization of helium in the stellar wind of stars with low reddening.

  16. Multilayer x-ray mirrors for the objective crystal spectrometer on the Spectrum Roentgen Gamma satellite

    DEFF Research Database (Denmark)

    Louis, E.; Spiller, E.; Abdali, S.;

    1995-01-01

    equals 0.154 nm) were used to analyze the coatings. We found optimum performance of the mirrors when applying polishing for 40 s with 500 eV Kr+-ions at an angle of 20 degrees and an ion beam current of 20 mA. Using these parameters, we produced Co/C multilayer coatings on forty flat super-polished 6...... multiplied by 6 cm2 Si (111) crystals for the Objective Crystal Spectrometer on the Russian Spectrum Rontgen Gamma satellite. The coatings on the flight crystals have a period Lambda of 3.95 plus or minus 0.02 nm and a reflectivity of more than 8% averaged over s- and p-polarization over the entire...

  17. Detection of an unidentified emission line in the stacked X-ray spectrum of galaxy clusters

    Energy Technology Data Exchange (ETDEWEB)

    Bulbul, Esra; Foster, Adam; Smith, Randall K.; Randall, Scott W. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Markevitch, Maxim [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Loewenstein, Michael, E-mail: ebulbul@cfa.harvard.edu [CRESST and X-ray Astrophysics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2014-07-01

    We detect a weak unidentified emission line at E = (3.55-3.57) ± 0.03 keV in a stacked XMM-Newton spectrum of 73 galaxy clusters spanning a redshift range 0.01-0.35. When the full sample is divided into three subsamples (Perseus, Centaurus+Ophiuchus+Coma, and all others), the line is seen at >3σ statistical significance in all three independent MOS spectra and the PN 'all others' spectrum. It is also detected in the Chandra spectra of the Perseus Cluster. However, it is very weak and located within 50-110 eV of several known lines. The detection is at the limit of the current instrument capabilities. We argue that there should be no atomic transitions in thermal plasma at this energy. An intriguing possibility is the decay of sterile neutrino, a long-sought dark matter particle candidate. Assuming that all dark matter is in sterile neutrinos with m{sub s} = 2E = 7.1 keV, our detection corresponds to a neutrino decay rate consistent with previous upper limits. However, based on the cluster masses and distances, the line in Perseus is much brighter than expected in this model, significantly deviating from other subsamples. This appears to be because of an anomalously bright line at E = 3.62 keV in Perseus, which could be an Ar XVII dielectronic recombination line, although its emissivity would have to be 30 times the expected value and physically difficult to understand. Another alternative is the above anomaly in the Ar line combined with the nearby 3.51 keV K line also exceeding expectation by a factor of 10-20. Confirmation with Astro-H will be critical to determine the nature of this new line.

  18. Monte Carlo simulation of the interaction of X-ray spectrum with human tissue, in the energies range of diagnostic radiology

    International Nuclear Information System (INIS)

    Full text: This paper is an approach to an increasingly complete knowledge about the nature of the processes that occur during a simple examination of radiological diagnosis; know as X-rays are produced and how they will put their energy into the tissue of patients when they are subjected to an examination of radiological diagnosis. First, using the MCNP code an X-rays tube was simulated, where electrons are emitted from a filament (cathode) which travel a certain distance with a certain kinetic energy and then be stopped suddenly in the tungsten target. The X-rays emitted as a result of this interaction, are previously filtered through the inherent filter of Pyrex glass and then by a thin aluminum foil before quantification as an X-rays spectrum. 6 spectra (for 60, 80, 100, 120 and 140 KeV) were obtained. Second, using the Penelope code was simulated the interaction of the X-rays spectrum, obtained in the first part with human tissue, putting as simile of human tissue water phantoms of different thicknesses. As final result: dose of energy deposited (in 2 and 3-dimensional) and reflected, absorbed and transmitted photons spectra. (Author)

  19. Soft X-ray spectrum of BL Lacertae object AO 0235+164 as a tracer of elemental abundances at z approximately 0.5

    Science.gov (United States)

    Madejski, Greg

    1994-01-01

    We report the soft X-ray spectrum of BL Lac object AO 0235+164, observed with the Einstein Observatory Imaging Proportional Counter (IPC). This object (z = 0.94) has an intervening galaxy (or a protogalactic disk) at z = 0.524 present in the line of sight, producing both radio and optical absorption lines in the background BL Lac continuum. The X-ray spectrum exhibits a substantial soft X-ray cutoff, corresponding to several times that expected from our own Galaxy; we interpret that excess cutoff as due to the intervening galaxy. The comparison of the hydrogen column density inferred from the 21 cm radio data and the X-ray absorption allows, in principle, the determination of the elemental abundances in the intervening galaxy. However, the uncertainties in both the H I spin temperature and X-ray spectral parameters only loosely restrict these abundances to be 2 +/- 1 solar, which even at the lower limit appears higher than that inferred from studies of samples of optical absoprtion-line systems.

  20. Sensitivity Analysis Applied to Atomic Data Used for X-ray Spectrum Synthesis

    Science.gov (United States)

    Kallman, Tim

    2006-01-01

    A great deal of work has been devoted to the accumulation of accurate quantities describing atomic processes for use in analysis of astrophysical spectra. But in many situations of interest the interpretation of a quantity which is observed, such as a line flux, depends on the results of a modeling- or spectrum synthesis code. The results of such a code depends in turn 011 many atomic rates or cross sections, and the sensitivity of the observable quantity on the various rates and cross sections may be non-linear and if so cannot easily be derived analytically. In such cases the most practical approach to understanding the sensitivity of observables to atomic cross sections is to perform numerical experiments, by calculating models with various rates perturbed by random (but known) factors. In addition, it is useful to compare the results of such experiments with some sample observations, in order to focus attention on the rates which are of the greatest relevance to real observations. In this paper I will present some attempts to carry out this program, focussing on two sample datasets taken with the Chandra HETG. I will discuss the sensitivity of synthetic spectra to atomic data affecting ionization balance, temperature, and line opacity or emissivity, and discuss the implications for the ultimate goal of inferring astrophysical parameters.

  1. 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.

  2. The complex optical to soft x-ray spectrum of the low-redshift radio-quiet quasars

    Science.gov (United States)

    Fiore, Fabrizio; Elvis, Martin; Mcdowell, Jonathan C.; Siemiginowska, Aneta; Wilkes, Belinda J.

    1994-01-01

    Eight high signal-to-noise ROSAT Position Sensitive Proportional Counter (PSPC) observations of six low-redshift (o.048 less than z less than 0.155) radio-quiet quasars have been analyzed to study ant soft excess. All the spectra can, at least roughly, be described int eh 0.1-2.5 keV band by simple power laws reduced at low energies by Galactic absorption. The strong oxygen edges seen in the PSPC spectra of several Seyfert galaxies and quasars are not observed in this sample. The limits implied for the abount of absorbing gas intrinsic to the quasars are particularly tight: of the order of approximately 10(exp 20)/sq cm. THe range of energy indices is broad: 1.3 less than alpha(sub E) less than 2.3. The energy indices are systematically steeper than those found in the same sources at higher energies (by DELTA alpha(sub E) approximately 0.5-1 with respect to Ginga or EXOSAT (2-10 keV) measurements, and by DELTA alpha(sub E) approximately 0.5 with respect to IPC (0.2-3.5 keV) measurements). This suggests a break between the hard and soft components in the keV region and, therefore, that the PSPC spectra are strongly dominated by the soft compnents. In fact, a fit tot he composite, high signal-to-noise spectrum reveals a significant excess above approximately 1 keV withrespect to the simple power-law model. No evidence for strong emission lines is found in any of the quasars. This argues against emission from an ionized plasma as the main contributor to the soft X-ray compnentunless there is a distribution of te mperatures. If the soft X-ray spectrum of thee quasars is dominated by radiation reflected by the photoinonized surface of an accretion disk, the absence of strong emissionlines suggests high ionization parameters and therefore high accretion rates. We include in two Appendices a comarison of the two official PSPC resolution matrices, those released on1992 March and on 1993 January, a discussion of the amplitude of the residual systematic uncertainties in 1993

  3. 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...

  4. Spectrum reconstruction with X rays and flat panel wedge PMMA by Monte Carlo codes and Penelope MCNPS; Reconstruccion del esptro de rayos X con flat panel y cuna de PMMa mediante los codigos de monte Carlo Penelope y MCNP5

    Energy Technology Data Exchange (ETDEWEB)

    Pozuelo, F.; Querol, A.; Juste, B.; Gallardo, S.; Rodenas, J.; Verdu, G.

    2012-07-01

    Obtaining the primary spectrum of X-rays to determine the quality of a photon beam produced by an X-ray tube, since the dosimetric characteristics of a radiation beam to have a direct relation to the primary X-ray spectrum. In this work are studied, the depth dose curves obtained in the energy range of diagnostic radiology, between 40 and 130 keV.

  5. A Cutoff in the X-ray Fluctuation Power Density Spectrum of the Seyfert 1 Galaxy NGC 3516

    CERN Document Server

    Edelson, R; Edelson, Rick; Nandra, Kirpal

    1998-01-01

    During 1997 March-July, XTE observed the bright, strongly variable Seyfert 1 galaxy NGC 3516 once every ~12.8 hr for 4.5 months and nearly continuously (with interruptions due to SAA passage but not Earth occultation) for a 4.2 day period in the middle. These were followed by ongoing monitoring once every ~4.3 days. These data are used to construct the first well-determined X-ray fluctuation power density spectrum (PDS) of an active galaxy to span more than 4 decades of usable temporal frequency. The PDS shows no signs of any strict or quasi-periodicity, but does show a progressive flattening of the power-law slope from -1.74 at short time scales to -0.73 at longer time scales. This is the clearest observation to date of the long-predicted cutoff in the PDS. The characteristic variability time scale corresponding to this cutoff temporal frequency is 1 month. Although it is unclear how this time scale may be interpreted in terms of a physical size or process, there are several promising candidate models. The P...

  6. Inner-shell photoionized x-ray lasers

    Energy Technology Data Exchange (ETDEWEB)

    Moon, S.J.

    1998-06-01

    The inner-shell photoionized x-ray lasing scheme is an attractive method for achieving x-ray lasing at short wavelengths, via population inversion following inner-shell photoionization (ISPI). This scheme promises both a short wavelength and a short pulse source of coherent x rays with high average power. In this dissertation a very complete study of the ISPI x-ray laser scheme is done concerning target structure, filter design and lasant medium. An investigation of the rapid rise time of x-ray emission from targets heated by an ultra-short pulse high-intensity optical laser was conducted for use as the x-ray source for ISPI x-ray lasing. Lasing by this approach in C at a wavelength of 45 {angstrom} requires a short pulse (about 50 fsec) driving optical laser with an energy of 1-5 J and traveling wave optics with an accuracy of {approximately} 15 {micro}m. The optical laser is incident on a high-Z target creating a high-density plasma which emits a broadband spectrum of x rays. This x-ray source is passed through a filter to eliminate the low-energy x rays. The remaining high-energy x rays preferentially photoionize inner-shell electrons resulting in a population inversion. Inner-shell photoionized x-ray lasing relies on the large energy of a K-{alpha} transition in the initially neutral lasant. The photo energy required to pump this scheme is only slightly greater than the photon energy of the lasing transition yielding a lasing scheme with high quantum efficiency. However, the overall efficiency is reduced due to low x-ray conversion efficiency and the large probability of Auger decay yielding an overall efficiency of {approximately} 10{sup {minus}7} resulting in an output energy of {micro}J's. They calculate that a driving laser with a pulse duration of 40 fs, a 10{micro}m x 1 cm line focus, and an energy of 1 J gives an effective gain length product (gl) of 10 in C at 45 {angstrom}. At saturation (gl {approximately} 18) they expect an output of

  7. ASCA View of the Supernova Remnant Gamma Cygni (G78.2+2.1) Bremsstrahlung X-ray Spectrum from Loss-flattened Electron Distribution

    CERN Document Server

    Uchiyama, Y; Aharonian, F A; Mattox, J R; Uchiyama, Yasunobu; Takahashi, Tadayuki; Aharonian, Felix; Mattox, John

    2002-01-01

    We perform X-ray studies of the shell-type supernova remnant (SNR) gamma-Cygni associated with the brightest EGRET unidentified source 3EG J2020+4017. In addition to the thermal emissions with characteristic temperature of kT = 0.5-0.9 keV, we found an extremely hard X-ray component from several clumps localized in the northern part of the remnant. This component is described by a power-law with a photon index of 0.8-1.5. Both the absolute flux and the spectral shape of the nonthermal X-rays cannot be explained by the synchrotron or inverse-Compton mechanisms. We argue that the unusually hard X-ray spectrum can be naturally interpreted in terms of nonthermal bremsstrahlung from Coulomb-loss-flattened electron distribution in dense environs with the gas density about 10 to 100 cm^-3 . For given spectrum of the electron population, the ratio of the bremsstrahlung X- and gamma-ray fluxes depends on the position of the ``Coulomb break'' in the electron spectrum. The bulk of gamma-rays detected by EGRET would come...

  8. Research of the X-ray spectrum in the digital image acquisition and processing for internal disturbs detection in mangoes (Mangifera indica l.)

    International Nuclear Information System (INIS)

    In this work, digital image processing was associated to X-ray beam relevant to watching internal injuries, such as breakdown, soft nose and other physiological disturbs in mangoes CV Tommy Atkins. The X-ray source was a high frequency generator operating to a high tension between 14 to 35 kV on a molybdenum target tube, which generate X-ray characteristic near from 18,5 keV and 20 keV (k an l shell) plus a continuous spectrum, thought to be proper to get radiological images from mangoes in different maturation stages. Different filtrations and pseudo-colors technique were used to process the digital images produced. Results, from a group of comparative images, show the feasibility to detect several classes of internal disorders as well as others produced in packing houses and transport of mangoes. (author)

  9. Gold nanoparticles: BSA (Bovine Serum Albumin) coating and X-ray irradiation produce variable-spectrum photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kuo-Hao [Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan (China); Institute of Physics, Academia Sinica, Taipei 115, Taiwan (China); Lai, Sheng-Feng [Institute of Physics, Academia Sinica, Taipei 115, Taiwan (China); Department of Engineering Science, National Cheng Kung University, Tainan 701, Taiwan (China); Lin, Yan-Cheng; Chou, Wu-Ching [Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan (China); Ong, Edwin B.L. [Institute of Physics, Academia Sinica, Taipei 115, Taiwan (China); Tan, Hui-Ru [Institute of Materials Research and Engineering, 3 Research Link, 117602 (Singapore); Tok, Eng Soon [Physics Department, National University of Singapore, 117542 (Singapore); Yang, C.S. [Center for Nanomedicine, National Health Research Institutes, Miaoli 350, Taiwan (China); Margaritondo, G. [Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Hwu, Y., E-mail: phhwu@sinica.edu.tw [Institute of Physics, Academia Sinica, Taipei 115, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701, Taiwan (China); Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung 202, Taiwan (China)

    2015-01-15

    We show that by using different x-ray irradiation times of BSA-coated Au nanoparticles (NPs) we can change their ultraviolet-stimulated photoluminescence and shift the spectral weight over the visible spectral range. This is due to the interplay of two emission bands, one due to BSA and the other related to gold. The emission properties did not change with time over a period of several months. - Highlights: • Gold nanoparticles (Au NPs) coated with Bovine Serum Albumin (BSA) are synthesized by x-ray irradiation. • BSA coated AuNPs with ∼1 nm size show strong photoluminescence in red by UV excitation. • The blue photoluminescence of BSA increase with x-ray irradiation. • Increase x-ray irradiation time during the synthesis shift the color of the colloid from red to blue.

  10. X-ray astronomy

    International Nuclear Information System (INIS)

    This book contains the lectures, and the most important seminars held at the NATO meeting on X-Ray astronomy in Erice, July 1979. The meeting was an opportune forum to discuss the results of the first 8-months of operation of the X-ray satellite, HEAO-2 (Einstein Observatory) which was launched at the end of 1978. Besides surveying these results, the meeting covered extragalactic astronomy, including the relevant observations obtained in other portions of the electromagnetic spectrum (ultra-violet, optical, infrared and radio). The discussion on galactic X-ray sources essentially covered classical binaries, globular clusters and bursters and its significance to extragalactic sources and to high energy astrophysics was borne in mind. (orig.)

  11. XMM-Newton reveals a Seyfert-like X-ray spectrum in the z=3.6 QSO B1422+231

    CERN Document Server

    Dadina, M; Cappi, M; Lanzuisi, G; Ponti, G; De Marco, B; Chartas, G; Giustini, M

    2016-01-01

    Matter flows in the central regions of quasars during their active phases are probably responsible for the properties of the super-massive black holes and that of the bulges of host galaxies. To understand how this mechanism works, we need to characterize the geometry and the physical state of the accreting matter at cosmological redshifts. The few high quality X-ray spectra of distant QSO have been collected by adding sparse pointings of single objects obtained during X-ray monitoring campaigns. This could have introduced spurious spectral features due to source variability. Here we present a single epoch, high-quality X-ray spectrum of the z=3.62 quasar B1422+231 whose flux is enhanced by gravitationally lensing (F$_{2-10 keV}\\sim$10$^{-12}$erg s$^{-1}$ cm$^{-2}$). The X-ray spectrum of B1422+231 is found to be very similar to the one of a typical nearby Seyfert galaxy. Neutral absorption is detected (N$_{H}\\sim$5$\\times$10$^{21}$ cm$^{-2}$ at the redshift of the source) while a strong absorption edge is me...

  12. Broadband X-ray Spectral Investigations of Magnetars, 4U 0142+61, 1E 1841-045, 1E 2259+586, and 1E 1048.1-5937

    CERN Document Server

    Weng, Shan-Shan

    2015-01-01

    We have generated an extended version of rather simplified but physically oriented three-dimensional magnetar emission model, STEMS3D, to allow spectral investigations up to 100 keV. We have then applied it to the broadband spectral 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 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 the 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 ha...

  13. Determination voltage applied to an X-ray tube using the spectrum; Determinacao da tensao aplicada em um tubo de raios-X usando o espectro

    Energy Technology Data Exchange (ETDEWEB)

    Albuquerque, M.A.G.; David, M.G.; Almeida, Carlos Eduardo de; Magalhaes, Luis Alexandre Goncalves, E-mail: malbuqueque@hotmail.com [Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ (Brazil). Lab. de Ciencias Radiologicas; Peixoto, Guilherme [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2015-07-01

    This work shows the methodology used to determine the voltage applied in an X-ray tube using their spectra. The measurements were made using a detector Cadmium telluride . Before the measurements are carried out detector was calibrated with a source of {sup 241}Am. After obtaining the spectra , the mean energies were calculated , the electron accelerating potential (k Vp ) of each spectrum is constructed a calibration straight for the kVp this tube. (author)

  14. 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.

  15. The X-ray Spectrum and Spectral Energy Distribution of FIRST J155633.8+351758: a LoBAL Quasar with a Probable Polar Outflow

    CERN Document Server

    Berrington, Robert C; Gallagher, Sarah C; Ganguly, Rajib; Shang, Zhaohui; DiPompeo, Michael; Chatterjee, Ritaban; Lacy, Mark; Gregg, Michael D; Hall, Patrick B; Laurent-Muehleisen, S A

    2013-01-01

    We report the results of a new 60 ks Chandra X-ray Observatory Advanced CCD Imaging Spectrometer S-array (ACIS-S) observation of the reddened, radio-selected, highly polarized `FeLoBAL' quasar FIRST J1556+3517. We investigated a number of models of varied sophistication to fit the 531-photon spectrum. These models ranged from simple power laws to power laws absorbed by hydrogen gas in differing ionization states and degrees of partial covering. Preferred fits indicate that the intrinsic X-ray flux is consistent with that expected for quasars of similarly high luminosity, i.e., an intrinsic, dereddened and unabsorbed optical to X-ray spectral index of -1.7. We cannot tightly constrain the intrinsic X-ray power-law slope, but find indications that it is flat (photon index Gamma = 1.7 or flatter at a >99% confidence for a neutral hydrogen absorber model). Absorption is present, with a column density a few times 10^23 cm^-2, with both partially ionized models and partially covering neutral hydrogen models providi...

  16. 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)

  17. A multielement Ge detector with complete spectrum readout for x-ray fluorescence microprobe and microspectroscopy (abstract)

    Science.gov (United States)

    Rivers, Mark L.; Sutton, Stephen R.; Rarback, Harvey

    1995-02-01

    Multielement Ge and Si(Li) detectors have been used in recent years to improve the increase count rate capability and to improve the solid-angle efficiency in fluorescence x-ray absorption spectroscopy (XAS). Such systems have typically been equipped with one or more single-channel analyzers (SCAs) for each detector element. Such SCA-based electronics are sufficient when only the counts in one or two well-resolved peaks are of interest. For the fluorescence (XRF) microprobe at beamline X-26A at the NSLS, SCA-based electronics were not a satisfactory solution for two reasons: (1) for XRF experiments, the entire fluorescence spectrum is required; (2) for micro-XAS studies of trace elements in complex systems, the fluorescence peak often sits on a significant background or partially overlaps another fluorescence peak, requiring software background subtraction or peak deconvolution. An electronics system which permits collection of the entire fluorescence spectrum from each detector element has been designed. The system is made cost-effective by the use of analog multiplexors, reducing the number of analog-to-digital converters (ADCs) and multichannel analyzers (MCAs) required. The system was manufactured by Canberra Industries and consists of: (1) a 13 element Ge detector (11 mm diameter detector elements), (2) 13 NIM spectroscopy amplifiers with programmable gains, (3) four analog multiplexors with maximum of eight inputs each, (4) four ADCs with programmable offsets and gains and 800 ns conversion time, and (5) two MCAs with Ethernet communications ports and two ADC inputs each. The amplifiers have shaping times which are adjustable from 0.5 to 12 μs. The analog multiplexors were modified to perform pileup rejection. The analog multiplexing does not significantly reduce the count rate capability of the system, even at the shortest amplifier shaping times. The average detector resolution is 170 eV at 12 μs shaping time and 200 eV at 4 μs shaping time. The maximum

  18. Broadband detection of squeezed vacuum: A spectrum of quantum states

    OpenAIRE

    Breitenbach, Gerd; Illuminati, Fabrizio; Schiller, Stephan; Mlynek, Jurgen

    1999-01-01

    We demonstrate the simultaneous quantum state reconstruction of the spectral modes of the light field emitted by a continuous wave degenerate optical parametric amplifier. The scheme is based on broadband measurement of the quantum fluctuations of the electric field quadratures and subsequent Fourier decomposition into spectral intervals. Applying the standard reconstruction algorithms to each bandwidth-limited quantum trajectory, a "spectrum" of density matrices and Wigner functions is obtai...

  19. Patterning of graphite nanocones for broadband solar spectrum absorption

    Directory of Open Access Journals (Sweden)

    Yaoran Sun

    2015-06-01

    Full Text Available We experimentally demonstrate a broadband vis-NIR absorber consisting of 300-400 nm nanocone structures on highly oriented pyrolytic graphite. The nanocone structures are fabricated through simple nanoparticle lithography process and analyzed with three-dimensional finite-difference time-domain methods. The measured absorption reaches an average level of above 95% over almost the entire solar spectrum and agrees well with the simulation. Our simple process offers a promising material for solar-thermal devices.

  20. X-Ray- and fast neutron induced mutations in Arabidopsis thaliana, and the effect of dithiothreitol upon the mutant spectrum

    NARCIS (Netherlands)

    Dellaert, L.M.W.

    1980-01-01

    The genetic effects of X-ray and fast neutron seed-irradiation of Arabidopsis thaliana (L.) Heynh., and the influence of a pre-irradiation treatment with the radio-protector dithiothreitol (DTT), are the main subjects of this thesis.Chapters I and II deal with the effects of radiation - with or with

  1. High-Resolution {\\it Chandra} Spectroscopy of tau Scorpii A Narrow-Line X-ray Spectrum From a Hot Star

    CERN Document Server

    Cohen, D H; MacFarlane, J J; Miller, N A; Cassinelli, J P; Owocki, S P; Liedahl, D A; Cohen, David H.; Messi\\`{e}res, Genevi\\`{e}ve E. de; Farlane, Joseph J. Mac; Miller, Nathan A.; Cassinelli, Joseph P.; Owocki, Stanley P.; Liedahl, Duane A.

    2003-01-01

    Long known to be an unusual early-type star by virtue of its hard and strong X-ray emission, tau Scorpii poses a severe challenge to the standard picture of O star wind-shock X-ray emission. The Chandra HETGS spectrum now provides significant direct evidence that this B0.2 star does not fit this standard wind-shock framework. The many emission lines detected with the Chandra gratings are significantly narrower than what would be expected from a star with the known wind properties of tau Sco, although they are broader than the corresponding lines seen in late-type coronal sources. While line ratios are consistent with the hot plasma on this star being within a few stellar radii of the photosphere, from at least one He-like complex there is evidence that the X-ray emitting plasma is located more than a stellar radius above the photosphere. The Chandra spectrum of tau Sco is harder and more variable than those of other hot stars, with the exception of the young magnetized O star theta Ori C. We discuss these new...

  2. Cosmological constraints from the cluster contribution to the power spectrum of the soft X-ray background. New evidence for a low sigma_8

    CERN Document Server

    Diego-Rodriguez, J M; Silk, J; Barcons, X; Voges, W

    2003-01-01

    We use the X-ray power spectrum of the ROSAT all-sky survey in the R6 band (approximately 0.9-1.3 keV) to set an upper limit on the galaxy cluster power spectrum. The cluster power spectrum is modelled with a minimum number of robust assumptions regarding the structure of the clusters. The power spectrum of ROSAT sets an upper limit on the Omega_m-sigma_8 plane which excludes all the models with sigma_8 above sigma_8 = 0.5/(Omega_m^0.38) in a flat LCDM universe. We discuss the possible sources of systematic errors in our conclusions, mainly dominated by the assumed L_x-T relation. Alternatively, this relation could be constrained by using the X-ray power spectrum, if the cosmological model is known. Our conclusions suggest that only models with a low value of sigma_8 (sigma_8 < 0.8 for Omega_m = 0.3) may be compatible with our upper limit. We also find that models predicting lower luminosities in galaxy clusters are favoured. Reconciling our cosmological constraints with these arising by other methods migh...

  3. X-ray fluorescence spectrum of highly charged Fe ions driven by strong free-electron-laser fields

    CERN Document Server

    Oreshkina, Natalia S; Keitel, Christoph H; Harman, Zoltán

    2015-01-01

    The influence of nonlinear dynamical effects is analyzed on the observed spectra of controversial 3C and 3D astrophysically relevant x-ray lines in neonlike Fe${}^{16+}$ and the A, B, C lines in natriumlike Fe${}^{15+}$ ions. First, a large-scale configuration-interaction calculation of oscillator strengths is performed with the inclusion of higher-order electron-correlation effects. Also, quantum-electrodynamic corrections to the transition energies are calculated. Further considered dynamical effects provide a possible resolution of the discrepancy between theory and experiment found by recent x-ray free-electron-laser measurements of these controversial lines. We find that, for strong x-ray sources, the modeling of the spectral lines by a peak with an area proportional to the oscillator strength is not sufficient and nonlinear dynamical effects have to be taken into account. Thus, we advocate the use of light-matter-interaction models also valid for strong light fields in the analysis and interpretation of...

  4. Broadband Cooperative Spectrum Sensing Based on Distributed Modulated Wideband Converter

    Directory of Open Access Journals (Sweden)

    Ziyong Xu

    2016-09-01

    Full Text Available The modulated wideband converter (MWC is a kind of sub-Nyquist sampling system which is developed from compressed sensing theory. It accomplishes highly accurate broadband sparse signal recovery by multichannel sub-Nyquist sampling sequences. However, when the number of sparse sub-bands becomes large, the amount of sampling channels increases proportionally. Besides, it is very hard to adjust the number of sampling channels when the sparsity changes, because its undersampling board is designed by a given sparsity. Such hardware cost and inconvenience are unacceptable in practical applications. This paper proposes a distributed modulated wideband converter (DMWC scheme innovatively, which regards one sensor node as one sampling channel and combines MWC technology with a broadband cooperative spectrum sensing network perfectly. Being different from the MWC scheme, DMWC takes phase shift and transmission loss into account in the input terminal, which are unavoidable in practical application. Our scheme is not only able to recover the support of broadband sparse signals quickly and accurately, but also reduces the hardware cost of the single node drastically. Theoretical analysis and numerical simulations show that phase shift has no influence on the recovery of frequency support, but transmission loss degrades the recovery performance to a different extent. Nevertheless, we can increase the amount of cooperative nodes and select satisfactory nodes by a different transmission distance to improve the recovery performance. Furthermore, we can adjust the amount of cooperative nodes flexibly when the sparsity changes. It indicates DMWC is extremely effective in the broadband cooperative spectrum sensing network.

  5. Characterization of a radiographic system with broad energy band X-ray source

    International Nuclear Information System (INIS)

    High energy X-ray beams with broad band energy spectra allow performing radiographic analysis on different materials and objects of relevant interest that cannot be investigated with conventional X-ray sources. The quality of a radiographic image strongly depends on the characteristics of radiation source as the size of the X-ray emitting area, or focal spot, and the energy spectrum of the radiation. In this work the characterization of a broad-band energy Bremsstrahlung source obtained from a linac providing a 5.5 MeV electron beam colliding with a tungsten target is presented. In order to measure the focal-spot size an ad hoc slit camera has been designed and built and a specific technique was used. Furthermore an analysis of the energy spectrum of the beam was performed using a method based on X-ray diffraction by a mosaic crystal.

  6. An Fe XXVI Absorption Line in the Persistent Spectrum of the Dipping Low Mass X-ray Binary 1A 1744-361

    CERN Document Server

    Gavriil, Fotis P; Bhattacharyya, Sudip

    2009-01-01

    We report on Chandra X-ray Observatory (CXO) High-Energy Transmission Grating (HETG) spectra of the dipping Low Mass X-ray Binary (LMXB) 1A 1744-361 during its July 2008 outburst. We find that its persistent emission is well modeled by a blackbody (kT ~ 1.0 keV) plus power-law ($\\Gamma$ ~ 1.7) with an absorption edge at 7.6 keV. In the residuals of the combined spectrum we find a significant absorption line at 6.961+/-0.002 keV, consistent with the Fe XXVI (hydrogen-like Fe) 2 - 1 transition. We place an upper limit on the velocity of a redshifted flow of v 10^3.6 erg cm/s. The properties of this line are consistent with those observed in other dipping LMXBs. Using Rossi X-ray Timing Explorer (RXTE) data accumulated during this latest outburst we present an updated color-color diagram which clearly shows that 1A 1744-361 is an "atoll" source. Finally, using additional dips found in the RXTE and CXO data we provide an updated orbital period estimate of 52+/-5 minutes.

  7. 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 ...

  8. Comparison of Clinical and Laboratory Responses in Sheep and Dogs following Whole-Body Exposures to 250-Kvp X-Rays and Fission-Spectrum Neutrons

    International Nuclear Information System (INIS)

    Fifteen sheep and eight dogs were exposed to 400 rad (air dose) of pulsed fission-spectrum neutrons, and an equal number of sheep and 14 dogs to 400 r (midline air dose) 250 kVp X-rays. Seven additional sheep and four dogs served as un-irradiated controls. Control data were obtained for two weeks preceding the exposures and at frequent and regular intervals after the injury. In sheep, the most consistent clinical change was complete loss of wool by the 51st day post-exposure. The underlying skin was pink in colour closely resembling that of a mild blush sometimes noted in humans. Dogs did not demonstrate loss of hair. Formed blood elements, neutrophils, lymphocytes, and thrombocytes fell rapidly after the radiation in both species. At about post-exposure day 24 recovery in white cell numbers was noted only in the neutron groups. Thrombocyte levels decreased to safe level in both species but somewhat earlier in the dog. Recovery appeared during the third post-exposure week in both species ex posed to neutrons, but not in those given X-rays. Red blood-cell haematocrits showed significant drops in both groups of dogs by the ninth day, but neither group of sheep exhibited significant decrease in haematocrit values. Plasma Fe59 clearance rates were determined in the experimental subjects as a parameter of measurement of haematopoietic function. Prognostic implications of alteration in this parameter of haemapoiesis are discussed. The most significant gross-pathologic changes were confined to the lungs wherein extensive perivascular haemorrhage around the arteries was noted. On microscopic study the area of haemorrhage was observed to be within the advential-connective tissue and periarterial vessels. Thirty-day mortality for dogs was 50% following neutron exposures and 93% after the X-ray insult. In sheep neutrons produced 22% mortality and X-rays 80%. (author)

  9. Broadband detection of squeezed vacuum A spectrum of quantum states

    CERN Document Server

    Breitenbach, G; Schiller, S; Mlynek, J; Breitenbach, Gerd; Illuminati, Fabrizio; Schiller, Stephan; Mlynek, Jurgen

    1998-01-01

    We demonstrate the simultaneous quantum state reconstruction of the spectral modes of the light field emitted by a continuous wave degenerate optical parametric amplifier. The scheme is based on broadband measurement of the quantum fluctuations of the electric field quadratures and subsequent Fourier decomposition into spectral intervals. Applying the standard reconstruction algorithms to each bandwidth-limited quantum trajectory, a "spectrum" of density matrices and Wigner functions is obtained. The recorded states show a smooth transition from the squeezed vacuum to a vacuum state. In the time domain we evaluated the first order correlation function of the squeezed output field, showing good agreement with the theory.

  10. Interstellar X-ray Absorption Spectroscopy of Oxygen, Neon, and Iron with the Chandra LETGS Spectrum of X0614+091

    CERN Document Server

    Paerels, F B S; Van der Meer, R L J; Kaastra, J S; Kuulkers, E; Den Boggende, A J F; Predehl, P; Drake, J J; Kahn, S M; Savin, D W; McLaughlin, B M; Paerels, Frits; Drake, Jeremy J.; Kahn, Steven M.; Savin, Daniel W.; Laughlin, Brendan M. Mc

    2000-01-01

    We find resolved interstellar O K, Ne K, and Fe L absorption spectra in the Chandra Low Energy Transmission Grating Spectrometer spectrum of the low mass X-ray binary X0614+091. We measure the column densities in O and Ne, and find direct spectroscopic constraints on the chemical state of the interstellar O. These measurements probably probe a low-density line of sight through the Galaxy and we discuss the results in the context of our knowledge of the properties of interstellar matter in regions between the spiral arms.

  11. Optical Stimulated Luminescence (OSL) linearity test into x-ray narrowed series spectrum (NSS) and gamma rays

    International Nuclear Information System (INIS)

    SSDL has made a turnover of 600 units dosimeters Optically Stimulated Luminescence (OSL) product by Nagase Landauer. A total of 20 units were randomly selected to test the ability of OSL dosimeters as personal dosimeters to replace the film badge. OSL dosimeters are irradiated to X-rays with the capability of 80 kV (65 keV) and 200 kV X-ray (171 keV) NSS, Cs-137 gamma rays (662 keV) and Co-60 gamma rays (1250 keV). OSL dosimeters affixed to the surface of the water phantom dimensions 30 cm x 30 cm x 15 cm and irradiated tissue in personal dose equivalent at a depth of 10 mm, Hp (10) of 0.1, 0.3, 0.5, 0.8, 1.0, 2.0, 3.0, 4.0, 5.0 and 10.0 mSv. Two additional units will dosimeters irradiated at each dose indicated. Analysis results showed that the straightness R2 (linear regression coefficient) for the four radiation quality is approaching the 1(R2∼1). (author)

  12. Soft x-ray polarimeter laboratory tests

    Science.gov (United States)

    Murphy, Kendrah D.; Marshall, Herman L.; Schulz, Norbert S.; Jenks, Kevin; Sommer, Sophie J. B.; Marshall, Eric A.

    2010-07-01

    Multilayer-coated optics can strongly polarize X-rays and are central to a new design of a broad-band, soft X-ray polarimeter. We have begun laboratory work to verify the performance of components that could be used in future soft X-ray polarimetric instrumentation. We have reconfigured a 17 meter beamline facility, originally developed for testing transmission gratings for Chandra, to include a polarized X-ray source, an X-ray-dispersing transmission grating, and a multilayer-coated optic that illuminates a CCD detector. The X-rays produced from a Manson Model 5, multi-anode source are polarized by a multilayer-coated flat mirror. The current configuration allows for a 180 degree rotation of the source in order to rotate the direction of polarization. We will present progress in source characterization and system modulation measurements as well as null and robustness tests.

  13. Comets: mechanisms of x-ray activity

    Science.gov (United States)

    Ibadov, Subhon

    2016-07-01

    Basic mechanisms of X-ray activity of comets are considered, including D-D mechanism corresponding to generation of X-rays due to production of hot short-living plasma clumps at high-velocity collisions between cometary and interplanetary dust particles as well as M-M one corresponding to production of X-rays due to recombination of multicharge ions of solar wind plasma via charge exchange process at their collisions with molecules/atoms of the cometary atmospheres. Peculiarities of the variation of the comet X-ray spectrum and X-ray luminosity with variation of its heliocentric distance are revealed.

  14. Chest x-ray

    Science.gov (United States)

    Chest radiography; Serial chest x-ray; X-ray - chest ... You stand in front of the x-ray machine. You will be told to hold your breath when the x-ray is taken. Two images are usually taken. You will ...

  15. XMM-Newton reveals a Seyfert-like X-ray spectrum in the z = 3.6 QSO B1422+231

    Science.gov (United States)

    Dadina, M.; Vignali, C.; Cappi, M.; Lanzuisi, G.; Ponti, G.; De Marco, B.; Chartas, G.; Giustini, M.

    2016-08-01

    Context. Matter flows from the central regions of quasi-stellar objects (QSOs) during their active phases are probably responsible for the properties of the super-massive black holes and those of the bulges of host galaxies. To understand how this mechanism works, we need to characterize the geometry and the physical state of the accreting matter at cosmological redshifts, when QSO activity is at its peak. Aims: We aim to use X-ray data to probe the matter inflow at the very center of a QSO at z = 3.62. While complex absorption, the iron K emission line, reflection hump, and high-energy cutoff are known to be almost ubiquitous in nearby active galactic nuclei (AGN), only a few distant objects are known to exhibit some of them. Methods: The few high-quality spectra of distant QSO were collected by adding sparse pointings of single objects obtained during X-ray monitoring campaigns. This could have introduced spurious spectral features due to source variability and/or microlensing. To avoid such problems, we decided to collect a single-epoch and high-quality X-ray spectrum of a distant AGN. We thus picked up the z = 3.62 QSO B1422+231, whose flux, enhanced by gravitationally lensing, is proven to be among the brightest lensed QSOs in X-rays (F2-10 keV ~ 10-12 erg s-1 cm-2). Results: The X-ray spectrum of B1422+231 is found to be very similar to the one of a typical nearby Seyfert galaxy. Neutral absorption is clearly detected (NH ~ 5 × 1021 cm-2 at the redshift of the source), while a strong absorption edge is measured at E ~ 7.5 keV with an optical depth of τ ~ 0.14. We also find hints of the FeKα line in emission at E ~ 6.4 keV line (EW ≲ 70 eV), and a hump is detected in the E ~ 15 - 20 keV energy band (rest frame) in excess of what is predicted by a simple absorbed power-law. Conclusions: The spectrum can best be modeled with two rather complex models; one assumes ionized and partially covering matter along the line of sight, the other is characterized by a

  16. A NuSTAR Observation of the Reflection Spectrum of the Low-mass X-Ray Binary 4U 1728-34

    Science.gov (United States)

    Sleator, Clio C.; Tomsick, John A.; King, Ashley L.; Miller, Jon M.; Boggs, Steven E.; Bachetti, Matteo; Barret, Didier; Chenevez, Jérôme; Christensen, Finn E.; Craig, William W.; Hailey, Charles J.; Harrison, Fiona A.; Rahoui, Farid; Stern, Daniel K.; Walton, Dominic J.; Zhang, William W.

    2016-08-01

    We report on a simultaneous NuSTAR and Swift observation of the neutron star low-mass X-ray binary 4U 1728-34. We identified and removed four Type I X-ray bursts during the observation in order to study the persistent emission. The continuum spectrum is hard and described well by a blackbody with kT = 1.5 keV and a cutoff power law with Γ = 1.5, and a cutoff temperature of 25 keV. Residuals between 6 and 8 keV provide strong evidence of a broad Fe Kα line. By modeling the spectrum with a relativistically blurred reflection model, we find an upper limit for the inner disk radius of {R}{{in}}≤slant 2{R}{{ISCO}}. Consequently, we find that R NS ≤ 23 km, assuming M = 1.4 M ⊙ and a = 0.15. We also find an upper limit on the magnetic field of B ≤ 2 × 108 G.

  17. The ASCA X-Ray Spectrum Of The Broad-Line Radio Galaxy Pictor A A Simple Power Law With No Fe K-$\\alpha$ Line

    CERN Document Server

    Eracleous, M; Eracleous, Michael; Halpern, Jules P.

    1998-01-01

    We present the X-ray spectrum of the broad-line radio galaxy Pictor A as observed by ASCA in 1996. The main objective of the observation was to detect and study the profiles of the Fe~K$\\alpha$ lines. The motivation was the fact that the Balmer lines of this object show well-separated displaced peaks, suggesting an origin in an accretion disk. The 0.5-10 keV X-ray spectrum is described very well by a model consisting of a power law of photon index 1.77 modified by interstellar photoelectric absorption. We find evidence for neither a soft nor a hard (Compton reflection) excess. More importantly, we do not detect an Fe K-alpha line, in marked contrast with the spectra of typical Seyfert galaxies and other broad-line radio galaxies observed by ASCA. The 99%-confidence upper limit on the equivalent width of an unresolved line at a rest energy of 6.4 keV is 100 eV, while for a broad line (FWHM of approximately 60,000 km/s) the corresponding upper limit is 135 eV. We discuss several possible explanations for the we...

  18. A NuSTAR observation of the reflection spectrum of the low mass X-ray binary 4U 1728-34

    CERN Document Server

    Sleator, Clio C; King, Ashley L; Miller, Jon M; Boggs, Steven E; Bachetti, Matteo; Barret, Didier; Chenevez, Jerome; Christensen, Finn E; Craig, William W; Hailey, Charles J; Harrison, Fiona A; Rahoui, Farid; Stern, Daniel K; Walton, Dominic J; Zhang, William W

    2016-01-01

    We report on a simultaneous NuSTAR and Swift observation of the neutron star low-mass X-ray binary 4U 1728-34. We identified and removed four Type I X-ray bursts during the observation in order to study the persistent emission. The continuum spectrum is hard and well described by a black body with kT = 1.5 keV and a cutoff power law with {\\Gamma} = 1.5. Residuals between 6 and 8 keV provide strong evidence of a broad Fe K{\\alpha} line. By modeling the spectrum with a relativistically blurred reflection model, we find an upper limit for the inner disk radius of $R_{\\rm in} \\leq 2R_{\\rm ISCO}$ . Consequently we find that $R_{\\rm NS} \\leq 23$ km, assuming M = 1.4 $\\rm\\,M_{\\mathord\\odot}$ and a = 0.15. We also find an upper limit on the magnetic field of $B \\leq 2\\times 10^8$ G

  19. X-ray scattering measurements from thin-foil x-ray mirrors

    DEFF Research Database (Denmark)

    Christensen, Finn Erland; BYRNAK, BP; Hornstrup, Allan;

    1992-01-01

    Thin foil X-ray mirrors are to be used as the reflecting elements in the telescopes of the X-ray satellites Spectrum-X-Gamma (SRG) and ASTRO-D. High resolution X-ray scattering measurements from the Au coated and dip-lacquered Al foils are presented. These were obtained from SRG mirrors positione...

  20. TAILORING X-RAY BEAM ENERGY SPECTRUM TO ENHANCE IMAGE QUALITY OF NEW RADIOGRAPHY CONTRAST AGENTS BASED ON GD OR OTHER LANTHANIDES

    International Nuclear Information System (INIS)

    Gadovist, a 1.0-molar Gd contrast agent from Schering AG, Berlin Germany, in use in clinical MPI in Europe, was evaluated as a radiography contrast agent. In a collaboration with Brookhaven National Laboratory (BNL), Schering AG is developing several such lanthanide-based contrast agents, while BNL evaluates them using different x-my beam energy spectra. These energy spectra include a ''truly'' monochromatic beam (0.2 keV energy bandwidth) from the National Synchrotron Light Source (NSLS), BNL, tuned above the Gd K-edge, and x-ray-tube beams from different kVp settings and beam filtrations. Radiographs of rabbits' kidneys were obtained with Gadovist at the NSLS. Furthermore, a clinical radiography system was used for imaging rabbits' kidneys comparing Gadovist and Conray, an iodinated contrast agent. The study, using 74 kVp and standard Al beam filter for Conray and 66 kVp and an additional 1.5 mm Cu beam filter for Gadovist, produced comparable images for Gadovist and Conray; the injection volumes were the same, while the radiation absorbed dose for Gadovist was slightly smaller. A bent-crystal silicon monochromator operating in the Laue diffraction mode was developed and tested with a conventional x-ray tube beam; it narrows the energy spectrum to about 4 keV around the anode tungsten's Ku line. Preliminary beam-flux results indicate that the method could be implemented in clinical CT if x-ray tubes with approximately twice higher output become available

  1. Thoracic spine x-ray

    Science.gov (United States)

    Vertebral radiography; X-ray - spine; Thoracic x-ray; Spine x-ray; Thoracic spine films; Back films ... care provider's office. You will lie on the x-ray table in different positions. If the x-ray ...

  2. New Observations of the Solar 0.5-5 keV Soft X-ray Spectrum

    CERN Document Server

    Caspi, Amir; Warren, Harry P

    2015-01-01

    The solar corona is orders of magnitude hotter than the underlying photosphere, but how the corona attains such high temperatures is still not understood. Soft X-ray (SXR) emission provides important diagnostics for thermal processes in the high-temperature corona, and is also an important driver of ionospheric dynamics at Earth. There is a crucial observational gap between ~0.2 and ~4 keV, outside the ranges of existing spectrometers. We present observations from a new SXR spectrometer, the Amptek X123-SDD, which measured the spatially-integrated solar spectral irradiance from ~0.5 to ~5 keV, with ~0.15 keV FWHM resolution, during sounding rocket flights on 2012 June 23 and 2013 October 21. These measurements show that the highly variable SXR emission is orders of magnitude greater than that during the deep minimum of 2009, even with only weak activity. The observed spectra show significant high-temperature (5-10 MK) emission and are well fit by simple power-law temperature distributions with indices of ~6, ...

  3. Chandra X-ray spectroscopy of the focused wind in the Cygnus X-1 system I. The non-dip spectrum in the low/hard state

    CERN Document Server

    Hanke, Manfred; Nowak, Michael A; Pottschmidt, Katja; Schulz, Norbert S; Lee, Julia C

    2008-01-01

    We present analyses of a 50 ks observation of the supergiant X-ray binary system Cygnus X-1/HDE 226868 taken with the Chandra High Energy Transmission Grating Spectrometer (HETGS). Cyg X-1 was in its spectrally hard state and the observation was performed during superior conjunction of the black hole, allowing for the spectroscopic analysis of the accreted stellar wind along the line of sight. A significant part of the observation covers X-ray dips as commonly observed for Cyg X-1 at this orbital phase, however, here we only analyze the high count rate non-dip spectrum. The full 0.5-10 keV continuum can be described by a single model consisting of a disk, a narrow and a relativistically broadened Fe Kalpha line, and a power law component, which is consistent with simultaneous RXTE broad band data. We detect absorption edges from overabundant neutral O, Ne and Fe, and absorption line series from highly ionized ions and infer column densities and Doppler shifts. With emission lines of He-like Mg XI, we detect t...

  4. Probing the wind-wind collision in Gamma Velorum with high-resolution Chandra X-ray spectroscopy: evidence for sudden radiative braking and non-equilibrium ionization

    OpenAIRE

    Henley, D. B.; Stevens, I. R.; Pittard, J. M.

    2004-01-01

    We present a new analysis of an archived Chandra HETGS X-ray spectrum of the WR+O colliding wind binary Gamma Velorum. The spectrum is dominated by emission lines from astrophysically abundant elements: Ne, Mg, Si, S and Fe. From a combination of broad-band spectral analysis and an analysis of line flux ratios we infer a wide range of temperatures in the X-ray emitting plasma (~4-40 MK). As in the previously published analysis, we find the X-ray emission lines are essentially unshifted, with ...

  5. Exploring the nature of the broadband variability in the flat spectrum radio quasar 3C 273

    Science.gov (United States)

    Chidiac, C.; Rani, B.; Krichbaum, T. P.; Angelakis, E.; Fuhrmann, L.; Nestoras, I.; Zensus, J. A.; Sievers, A.; Ungerechts, H.; Itoh, R.; Fukazawa, Y.; Uemura, M.; Sasada, M.; Gurwell, M.; Fedorova, E.

    2016-05-01

    The detailed investigation of the broadband flux variability in the blazar 3C 273 allowed us to probe the location and size of emission regions and their physical conditions. We conducted correlation studies of the flaring activity in 3C 273, which was observed for the period between 2008 and 2012. The observed broadband variations were investigated using the structure function and the discrete correlation function methods. Starting from the commonly used power spectral density (PSD) analysis at X-ray frequencies, we extended our investigation to characterise the nature of variability at radio, optical, and γ-ray frequencies. The PSD analysis showed that the optical and infrared light-curve slopes are consistent with the slope of white-noise processes, while the PSD slopes at radio, X-ray, and γ-ray energies are consistent with red-noise processes. We found that the estimated fractional variability amplitudes strongly depend on the observed frequency. The flux variations at γ-ray and mm-radio bands are found to be significantly correlated. Using the estimated time lag of (110 ± 27) days between γ-ray and radio light-curves, where γ-ray variations lead the radio bands, we constrained the location of the γ-ray emission region at a de-projected distance of 1.2 ± 0.9 pc from the jet apex. Flux variations at X-ray bands were found to have a significant correlation with variations at both radio and γ-ray energies. The correlation between X-ray and γ-ray light curves indicates two possible time lags, which suggests that two components are responsible for the X-ray emission. A negative time lag of -(50 ± 20) days, where the X-rays are leading the emission, suggests that X-rays are emitted closer to the jet apex from a compact region (0.02-0.05 pc in size), most likely from the corona at a distance of (0.5 ± 0.4) pc from the jet apex. A positive time lag of (110 ± 20) days (γ-rays are leading the emission) suggests a jet-base origin of the other X-ray

  6. The hard synchrotron X-ray spectrum of the TeV BL Lac 1ES 1426+428

    CERN Document Server

    Wolter, A; Ghisellini, G; Tavecchio, F; Maraschi, L; Costamante, L; Celotti, A; Ghirlanda, G

    2007-01-01

    We have observed 1ES 1426+428 with INTEGRAL detecting it up to $\\sim$150 keV. The spectrum is hard, confirming that this source is an extreme BL Lac object, with a synchrotron component peaking, in a $\

  7. Circular intensity differential scattering (CIDS) measurements in the soft x-ray region of the spectrum (@16 eV to 500 eV)

    Energy Technology Data Exchange (ETDEWEB)

    Maestre, M.F. (Lawrence Berkeley Lab., CA (United States)); Bustamante, C. (Oregon Univ., Eugene, OR (United States). Dept. of Chemistry); Snyder, P. (Florida Atlantic Univ., Boca Raton, FL (United States). Dept. of Chemistry); Rowe, E.; Hansen, R. (Wisconsin Univ., Stoughton, WI (United States). Synchrotron Radiation Center)

    1991-03-01

    We propose the use of recently developed techniques of circular intensity differential scattering (CIDS), as extended to the soft x-ray region of the spectrum (16 eV to 500 eV), to study the higher order organization of the eukaryotic chromosome. CIDS is the difference in scattering power of an object when illuminated by right circularly polarized vs. left circularly polarized electromagnetic radiation of arbitrary wavelength. CIDS has been shown to be a very sensitive measure of the helical organization of the scattering object eg. the eukaryotic chromosome. Preliminary results of measurements of samples of bacteriophages and octopus sperm done at SRC, Wisconsin, show the technique to be very sensitive to the dimensional parameters of the particles interrogated by circularly polarized light. 7 refs., 5 figs.

  8. Expression, purification, crystallization, and preliminary X-ray crystallographic analysis of OXA-17, an extended-spectrum {beta}-lactamase conferring severe antibiotic resistance

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J. H., E-mail: msgjhlee@mju.ac.kr; Sohn, S. G., E-mail: sgsohn@mju.ac.kr; Jung, H. I., E-mail: jhinumber1@hanmail.net; An, Y. J., E-mail: anyj0120@hanmail.net; Lee, S. H., E-mail: sangheelee@mju.ac.kr [Myongji University, Drug Resistance Proteomics Laboratory, Department of Biological Sciences (Korea, Republic of)

    2013-07-15

    OXA-17, an extended-spectrum {beta}-lactamase (ESBL) conferring severe antibiotic resistance, hydrolytically inactivates {beta}-lactam antibiotics, inducing a lack of eradication of pathogenic bacteria by oxyimino {beta}-lactams and not helping hospital infection control. Thus, the enzyme is a potential target for developing antimicrobial agents against pathogens producing ESBLs. OXA-17 was purified and crystallized at 298 K. X-ray diffraction data from OXA-17 crystal have been collected to 1.85 A resolution using synchrotron radiation. The crystal of OXA-17 belongs to space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 48.37, b = 101.12, and c = 126.07 A. Analysis of the packing density shows that the asymmetric unit probably contains two molecules with a solvent content of 54.6%.

  9. X-ray (image)

    Science.gov (United States)

    X-rays are a form of ionizing radiation that can penetrate the body to form an image on ... will be shades of gray depending on density. X-rays can provide information about obstructions, tumors, and other ...

  10. Dental x-rays

    Science.gov (United States)

    X-ray - teeth; Radiograph - dental; Bitewings; Periapical film; Panoramic film ... dentist's office. There are many types of dental x-rays. Some are: Bitewing Periapical Palatal (also called occlusal) ...

  11. X-ray apparatus

    International Nuclear Information System (INIS)

    A diagnostic x-ray device, readily convertible between conventional radiographic and tomographic operating modes, is described. An improved drive system interconnects and drives the x-ray source and the imaging device through coordinated movements for tomography

  12. Dental x-rays

    Science.gov (United States)

    X-ray - teeth; Radiograph - dental; Bitewings; Periapical film; Panoramic film; Digital image ... dentist's office. There are many types of dental x-rays. Some of them are: Bitewing. Shows the crown ...

  13. Effect of fluoroscopic X-ray beam spectrum on air-kerma measurement accuracy: implications for establishing correction coefficients on interventional fluoroscopes with KAP meters.

    Science.gov (United States)

    Wunderle, Kevin A; Rakowski, Joseph T; Dong, Frank F

    2016-01-01

    The first goal of this study was to investigate the accuracy of the displayed reference plane air kerma (Ka,r) or air kerma-area product (Pk,a) over a broad spectrum of X-ray beam qualities on clinically used interventional fluoroscopes incorporating air kerma-area product meters (KAP meters) to measure X-ray output. The second goal was to investigate the accuracy of a correction coefficient (CC) determined at a single beam quality and applied to the measured Ka,r over a broad spectrum of beam qualities. Eleven state-of-the-art interventional fluoroscopes were evaluated, consisting of eight Siemens Artis zee and Artis Q systems and three Philips Allura FD systems. A separate calibrated 60 cc ionization chamber (external chamber) was used to determine the accuracy of the KAP meter over a broad range of clinically used beam qualities. For typical adult beam qualities, applying a single CC deter-mined at 100 kVp with copper (Cu) in the beam resulted in a deviation of < 5% due to beam quality variation. This result indicates that applying a CC determined using The American Association of Physicists in Medicine Task Group 190 protocol or a similar protocol provides very good accuracy as compared to the allowed ± 35% deviation of the KAP meter in this limited beam quality range. For interventional fluoroscopes dedicated to or routinely used to perform pediatric interventions, using a CC established with a low kVp (~ 55-60 kVp) and large amount of Cu filtration (~ 0.6-0.9 mm) may result in greater accuracy as compared to using the 100 kVp values. KAP meter responses indicate that fluoroscope vendors are likely normalizing or otherwise influencing the KAP meter output data. Although this may provide improved accuracy in some instances, there is the potential for large discrete errors to occur, and these errors may be difficult to identify. PMID:27167287

  14. 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 your ... different amounts of radiation. Calcium in bones absorbs x-rays the most, so bones look white. Fat and ...

  15. Chest X-Ray

    Medline Plus

    Full Text Available ... by: Image/Video Gallery Your radiologist explains chest x-ray. Transcript Welcome to Radiology Info dot org! Hello, ... you about chest radiography also known as chest x-rays. Chest x-rays are the most commonly performed ...

  16. X-Ray Imaging

    Science.gov (United States)

    ... Brain Surgery Imaging Clinical Trials Basics Patient Information X-Ray Imaging Print This Page X-ray imaging is perhaps the most familiar type of imaging. Images produced by X-rays are due to the different absorption rates of ...

  17. X-ray Spectral Variation of Eta Carinae through the 2003 X-ray Minimum

    OpenAIRE

    Hamaguchi, Kenji; Corcoran, Michael F.; Gull, Theodore; Ishibashi, Kazunori; Pittard, Julian M.; Hillier, D. John; Damineli, Augusto; Davidson, Kris; Nielsen, Krister E.; Kober, Gladys Vieira

    2007-01-01

    We report the results of an X-ray observing campaign on the massive, evolved star Eta Carinae, concentrating on the 2003 X-ray minimum as seen by the XMM-Newton observatory. These are the first spatially-resolved X-ray monitoring observations of the stellar X-ray spectrum during the minimum. The hard X-ray emission, believed to be associated with the collision of Eta Carinae's wind with the wind from a massive companion star, varied strongly in flux on timescales of days, but not significantl...

  18. On the Putative Detection of z>0 X-ray Absorption Features in the Spectrum of Markarian 421

    CERN Document Server

    Rasmussen, A P; Den Herder, J W A; Kaastra, J; Kahn, S M; Paerels, F; Herder, Jan Willem den; Kaastra, Jelle; Kahn, Steven M.; Paerels, Frits; Rasmussen, Andrew P.; Vries, Cor de

    2006-01-01

    In a series of papers, Nicastro et al. have claimed the detection of z>0 O VII absorption features in the spectrum of Mrk 421 obtained with the Chandra Low Energy Transmission Grating Spectrometer (LETGS). We evaluate those claims in the context of a high quality spectrum of the same source obtained with the Reflection Grating Spectrometer (RGS) on XMM-Newton. The data comprise over 955~ksec of usable exposure time and more than 26000 counts per 50 milliAngstroms at 21.6 Angstroms. We concentrate on the spectrally clean region (21.3 < lambda < 22.5 Angstrom) where sharp features due to the astrophysically abundant O VII may reveal an intervening, warm-hot intergalactic medium (WHIM). In spite of the fact that the sensitivity of the RGS data is higher than that of the original LETGS data presented by Nicastro et al., we do not confirm detection of any of the intervening systems claimed to date. Rather, we detect only three unsurprising, astrophysically expected features down to the Log(N)~14.6 (3sigma) s...

  19. 3.9 day orbital modulation in the TeV gamma-ray flux and spectrum from the X-ray binary LS 5039

    CERN Document Server

    Aharonian, F A; Bazer-Bachi, A R; Beilicke, M; Benbow, W; Berge, D; Bernlöhr, K; Boisson, C; Bolz, O; Borrel, V; Braun, I; Brown, A M; Buhler, R; Büsching, I; Carrigan, S; Chadwick, P M; Chounet, L M; Cornils, R; Costamante, L; Degrange, B; Dickinson, H J; Djannati-Ata, A; O'Connor-Drury, L; Dubus, G; Egberts, K; Emmanoulopoulos, D; Espigat, P; Feinstein, F; Ferrero, E; Fiasson, A; Fontaine, G; Funk, Seb; Funk, S; Fussling, M; Gallant, Y A; Giebels, B; Glicenstein, J F; Goret, P; Hadjichristidis, C; Hauser, D; Hauser, M; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hoffmann, A; Hofmann, W; Holleran, M; Horns, D; Jacholkowska, A; De Jager, O C; Kendziorra, E; Khelifi, B; Komin, N; Konopelko, A; Kosack, K; Latham, I J; Le Gallou, R; Lemiere, A; Lemoine-Goumard, M; Lohse, T; Martin, J M; Martineau-Huynh, O; Marcowith, A; Masterson, C; Maurin, G; McComb, T J L; Moulin, E; De Naurois, Mathieu; Nedbal, D; Nolan, S J; Noutsos, A; Orford, K J; Osborne, J L; Ouchrif, M; Panter, M; Pelletier, G; Pita, S; Pühlhofer, G; Punch, M; Raubenheimer, B C; Raue, M; Rayner, S M; Reimer, A; Reimer, O; Ripken, J; Rob, L; Rolland, L; Rowell, G; Sahakian, V V; Santangelo, A; Sauge, L; Schlenker, S; Schlickeiser, R; Schroder, R; Schwanke, U; Schwarzburg, S; Shalchi, A; Sol, H; Spangler, D; Spanier, F; Steenkamp, R; Stegmann, C; Superina, G; Tavernet, J P; Terrier, R; Tluczykont, M; Van Eldik, C; Vasileiadis, G; Venter, C; Vincent, P; Völk, H J; Wagner, S J; Ward, M

    2006-01-01

    New observations of LS 5039, a High Mass X-ray Binary comprising a massive star and compact object, were carried out with the High Energy Stereoscopic System of Cherenkov Telescopes (H.E.S.S.) in 2005 at very high energy (VHE) gamma-ray energies. These observations reveal that its flux and energy spectrum are modulated with the 3.9 day orbital period of the binary system. This is the first time in gamma-ray astronomy that orbital modulation has been observed, and periodicity clearly established using ground-based gamma-ray detectors. The VHE gamma-ray emission is largely confined to half of the orbit, peaking around the inferior conjunction epoch of the compact object. For this epoch, there is also a hardening of the energy spectrum in the energy range between 0.2 TeV and a few TeV. The flux vs. orbital phase profile provides the first clear indication of gamma-ray absorption via pair production within an astrophysical source, a process which is expected to occur if the gamma-ray production site is situated w...

  20. On the Putative Detection of Z>0 X-Ray Absorption Features in the Spectrum of Mrk 421

    Energy Technology Data Exchange (ETDEWEB)

    Rasmussen, Andrew P.; /SLAC /KIPAC, Menlo Park; Kahn, Steven M.; /SLAC /KIPAC, Menlo Park /Stanford U., Phys. Dept.; Paerels, Frits; /Columbia U., Astron. Astrophys.; Herder, Jan Willem den; Kaastra, Jelle; de Vries, Cor; /SRON, Utrecht

    2006-04-28

    In a series of papers, Nicastro et al. have claimed the detection of z > 0 O VII absorption features in the spectrum of Mrk 421 obtained with the Chandra Low Energy Transmission Grating Spectrometer (LETGS). We evaluate those claims in the context of a high quality spectrum of the same source obtained with the Reflection Grating Spectrometer (RGS) on XMM-Newton. The data comprise over 955 ksec of usable exposure time and more than 2.6 x 10{sup 4} counts per 50 m{angstrom} at 21.6 {angstrom}. We concentrate on the spectrally clean region (21.3 < {lambda} < 22.5 {angstrom}) where sharp features due to the astrophysically abundant O VII may reveal an intervening, warm-hot intergalactic medium (WHIM). In spite of the fact that the sensitivity of the RGS data is higher than that of the original LETGS data presented by Nicastro et al., we do not confirm detection of any of the intervening systems claimed to date. Rather, we detect only three unsurprising, astrophysically expected features down to the log (N{sub i}) {approx} 14.6 (3{sigma}) sensitivity level. Each of the two purported WHIM features is rejected with a statistical confidence that exceeds that reported for its initial detection. While we can not rule out the existence of fainter, WHIM related features in these spectra, we suggest that previous discovery claims were premature. A more recent paper by Williams et al. claims to have demonstrated that the RGS data we analyze here do not have the resolution or statistical quality required to confirm or deny the LETGS detections. We show that the Williams et al. reduction of the RGS data was highly flawed, leading to an artificial and spurious degradation of the instrument response. We carefully highlight the differences between our analysis presented here and those published by Williams et al.

  1. 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.

  2. 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...

  3. Theory of Spin-State Selective Nonlocal Screening in Co 2p X-ray Photoemission Spectrum of LaCoO3

    Science.gov (United States)

    Hariki, Atsushi; Yamanaka, Akihiro; Uozumi, Takayuki

    2015-07-01

    The Co 2p X-ray photoemission spectrum (XPS) of LaCoO3 is investigated using a dp model simulating Co 3d and O 2p orbitals by means of a dynamical mean-field approach under the perovskite crystal structure. Across the spin-state transition from the low-spin to the high-spin state, the Co 2p3/2 main-line structure is substantially changed beyond expectation of a CoO6 cluster model calculation. In addition to the Coulombic multiplet effect, the origin of the spectral change is attributed to the nonlocal screening (NLS) from the correlated 3d band located on the top of the valence band to the core-excited Co site in the final state, where the NLS is practically active only for the high-spin state. The spin-state selectivity of the NLS is closely related to not only the spin state of the core-excited Co ion but also the spin and orbital character of the occupied Co 3d band in crystals. We emphasize that the Co 2p XPS can be an informative probe to investigate the spin state of Co ions in Co oxides, such as LaCoO3.

  4. The origin of blue-shifted absorption features in the X-ray spectrum of PG 1211+143: Outflow or disc?

    CERN Document Server

    Gallo, L C

    2013-01-01

    In some radio-quiet active galaxies (AGN), high-energy absorption features in the x-ray spectra have been interpreted as Ultrafast Outflows (UFOs) -- highly ionised material (e.g. Fe XXV and Fe XXVI) ejected at mildly relativistic velocities. In some cases, these outflows can carry energy in excess of the binding energy of the host galaxy. Needless to say, these features demand our attention as they are strong signatures of AGN feedback and will influence galaxy evolution. For the same reason, alternative models need to be discussed and refuted or confirmed. Gallo & Fabian proposed that some of these features could arise from resonance absorption of the reflected spectrum in a layer of ionised material located above and corotating with the accretion disc. Therefore, the absorbing medium would be subjected to similar blurring effects as seen in the disc. A priori, the existence of such plasma above the disc is as plausible as a fast wind. In this work, we highlight the ambiguity by demonstrating that the a...

  5. X-ray absorption spectrum for guanosine-5{sup '}-monophosphate in water solution in the vicinity of the nitrogen K-edge observed in free liquid jet in vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Ukai, Masatoshi [Department of Applied Physics, Tokyo University of Agriculture and Technology, Koganei-shi Tokyo 184-8588 (Japan)], E-mail: ukai3@cc.tuat.ac.jp; Yokoya, Akinari [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Fujii, Kentaro [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Synchrotron Radiation Research Center, Japan Atomic Energy Agency (JAEA), Sayo-gun, Hyogo 679-5148 (Japan); Saitoh, Yuji [Synchrotron Radiation Research Center, Japan Atomic Energy Agency (JAEA), Sayo-gun, Hyogo 679-5148 (Japan)

    2008-10-15

    A new spectroscopy for direct effect of radiation damage to nucleic acids such as DNA and RNA is underway using a liquid beam sample in vacuum combined with soft-X-ray synchrotron radiation. We show the X-ray absorption spectrum (XANES) of liquid phase water at X-ray photon energy in the vicinity of oxygen K-shell absorption edge obtained from total photoelectron yields ejected from a pure water beam. We confirm a 'liquid sample in vacuum' for the present experiment by the measurements of the temperature dependence of the XANES spectrum for a liquid beam of pure water. Shown is the first measurement of the XANES spectrum for guanosine-5{sup '}-monophosphate (GMP), which is one of the fundamental nucleotide unit for RNA, in water solution at X-ray photon energy in the vicinity of nitrogen K-shell absorption edge involved in the 'water-window' region, which corresponds to a selective excitation of guanine site.

  6. X-ray - skeleton

    Science.gov (United States)

    A skeletal x-ray is an imaging test used to look at the bones. It is used to detect fractures , tumors, or ... in the health care provider's office by an x-ray technologist. You will lie on a table or ...

  7. Extremity x-ray

    Science.gov (United States)

    An extremity x-ray is an image of the hands, wrist, feet, ankle, leg, thigh, forearm humerus or upper arm, hip, shoulder ... term "extremity" often refers to a human limb. X-rays are a form of radiation that passes through ...

  8. X-ray interferometers

    International Nuclear Information System (INIS)

    An improved type of amplitude-division x-ray interferometer is described. The wavelength at which the interferometer can operate is variable, allowing the instrument to be used to measure x-ray wavelength, and the angle of inclination is variable for sample investigation. (U.K.)

  9. X-Rays spectrum and air kerma during a mammography study;Espectro de los rayos X y kerma en aire durante un estudio mamografico

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez G, J. [Instituto Nacional de Estadistica Geografia e Informatica, Direccion General de Innovacion y Tecnologia de Informacion, Av. Heroes de Nacozari Sur No. 2301, Fracc. Jardines del Parque, 20276 Aguascalientes (Mexico); Hernandez V, R.; Chacon R, A.; Vega C, H. R., E-mail: ramirezgonzalezjaime@yahoo.com.m [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2009-10-15

    The X-rays spectrum produced in a mammography has been calculated by means of Monte Carlo methods. In this calculation series it is modeled the electrons source, the target and the filter. The spectra were calculated for an energy of the electrons of 28 keV and for targets of W, Mo and Rh. The calculations extended to analyze the effect that produces the filters inclusion in the spectra; the spectra of W-A1, Rh-Rh, Mo-Mo, Mo-Rh and Mo-Be were calculated this way. Using thermoluminescent dosemeters of ZrO{sub 2}+PTFE the air kerma was measured in five points located on a phantom made with acrylic and water when it is was exposed to a X-rays beam produced by electrons of 24 keV and 10 m A of current that it produces a mammography. The values of the air kerma on the entrance surface of the phantom were compared with the calculated values by means of Monte Carlo methods. The calculated spectra present a continuous component and another discreet and its form is similar to the reported spectra in the literature. The filters inclusion allows the elimination of the low energy photons that do not have utility in the obtaining of the mammography image and only they contribute to deposit a dose in the mamma. The values of the measured air kerma indicate that the five points receive the same air kerma approximately, what means that the beam is homogeneous, of the Monte Carlo calculations we find that the center receives a bigger dose which implies that the beam is not uniform, the explanation on this fact it is attributed to that a simple model was used in the calculations, nevertheless, the average of the air kerma measured on the entrance surface of the phantom was of 0.96 +- 0.03 m G, while the obtained by means of the calculations was of 0.96 +- 0.06 mGy, when comparing both significant differences do not exist. (Author)

  10. Achromatic approach to phase-based multi-modal imaging with conventional X-ray sources.

    Science.gov (United States)

    Endrizzi, Marco; Vittoria, Fabio A; Kallon, Gibril; Basta, Dario; Diemoz, Paul C; Vincenzi, Alessandro; Delogu, Pasquale; Bellazzini, Ronaldo; Olivo, Alessandro

    2015-06-15

    Compatibility with polychromatic radiation is an important requirement for an imaging system using conventional rotating anode X-ray sources. With a commercially available energy-resolving single-photon-counting detector we investigated how broadband radiation affects the performance of a multi-modal edge-illumination phase-contrast imaging system. The effect of X-ray energy on phase retrieval is presented, and the achromaticity of the method is experimentally demonstrated. Comparison with simulated measurements integrating over the energy spectrum shows that there is no significant loss of image quality due to the use of polychromatic radiation. This means that, to a good approximation, the imaging system exploits radiation in the same way at all energies typically used in hard-X-ray imaging. PMID:26193618

  11. 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.

  12. 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.

  13. X-ray source for mammography

    Science.gov (United States)

    Logan, Clinton M.

    1994-01-01

    An x-ray source utilizing anode material which shifts the output spectrum to higher energy and thereby obtains higher penetrating ability for screening mammography application, than the currently utilized anode material. The currently used anode material (molybdenum) produces an energy x-ray spectrum of 17.5/19.6 keV, which using the anode material of this invention (e.g. silver, rhodium, and tungsten) the x-ray spectrum would be in the 20-35 keV region. Thus, the anode material of this invention provides for imaging of breasts with higher than average x-ray opacity without increase of the radiation dose, and thus reduces the risk of induced breast cancer due to the radiation dose administered for mammograms.

  14. SAXJ1712.6-3739: a persistent hard X-ray source as monitored with INTEGRAL

    CERN Document Server

    Fiocchi, Mariateresa; Ubertini, Pietro; De Cesare, Giovanni

    2007-01-01

    The X-ray source SAXJ1712.6-3739 is a very weak Low Mass X-ray Binary discovered in 1999 with BeppoSAX and located in the Galactic Center. This region has been deeply investigated by the INTEGRAL satellite with an unprecedented exposure time, giving us an unique opportunity to study the hard X-ray behavior also for weak objects. The spectral results are based on the systematic analysis of all INTEGRAL observations covering the source position performed between February 2003 and October 2006. SAXJ1712.6-3739 did not shows any flux variation along this period as well as compared to previous BeppoSAX observation. Hence, to better constrain the physical parameters we combined both instrument data. Long INTEGRAL monitoring reveals, for the first time, that this X-ray burster is a weak persistent source, displaying a X-ray spectrum extended to high energy and spending most of the time in a low luminosity hard state. The broad-band spectrum is well modeled with a simple Comptonized model with a seed photons temperat...

  15. X-ray and fast neutron-induced mutations in Arabidopsis thaliana, and the effect of dithiothreitol upon the mutant spectrum

    International Nuclear Information System (INIS)

    The author discusses the genetic effects of X-ray and fast neutron seed-irradiation of Arabidopsis thaliana (L.) Heynh., and the influence of a pre-irradiation treatment with the radio-protector dithiothreitol (DTT). (Auth.)

  16. 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.

  17. Chandra X-ray spectroscopy of the very early O supergiant HD 93129A: constraints on wind shocks and the mass-loss rate

    CERN Document Server

    Cohen, David H; Leutenegger, Maurice A; MacArthur, James P; Wollman, Emma E; Sundqvist, Jon O; Fullerton, Alex W; Owocki, Stanley P

    2011-01-01

    We present analysis of both the resolved X-ray emission line profiles and the broadband X-ray spectrum of the O2 If* star HD 93129A, measured with the Chandra HETGS. This star is among the earliest and most massive stars in the Galaxy, and provides a test of the embedded wind shock scenario in a very dense and powerful wind. A major new result is that continuum absorption by the dense wind is the primary cause of the hardness of the observed X-ray spectrum, while intrinsically hard emission from colliding wind shocks contributes less than 10% of the X-ray flux. We find results consistent with the predictions of numerical simulations of the line-driving instability, including line broadening indicating an onset radius of X-ray emission of several tenths Rstar. Helium-like forbidden-to-intercombination line ratios are consistent with this onset radius, and inconsistent with being formed in a wind-collision interface with the star's closest visual companion at a distance of ~100 AU. The broadband X-ray spectrum ...

  18. 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 ...

  19. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... Professions Site Index A-Z X-ray (Radiography) - Bone Bone x-ray uses a very small dose ... limitations of Bone X-ray (Radiography)? What is Bone X-ray (Radiography)? An x-ray (radiograph) is ...

  20. Lumbosacral spine x-ray

    Science.gov (United States)

    X-ray - lumbosacral spine; X-ray - lower spine ... The test is done in a hospital x-ray department or your health care provider's office by an x-ray technician. You will be asked to lie on the x-ray table ...

  1. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... News Physician Resources Professions Site Index A-Z X-ray (Radiography) - Bone Bone x-ray uses a very ... of Bone X-ray (Radiography)? What is Bone X-ray (Radiography)? An x-ray (radiograph) is a noninvasive ...

  2. Abdomen X-Ray (Radiography)

    Science.gov (United States)

    ... News Physician Resources Professions Site Index A-Z X-ray (Radiography) - Abdomen Abdominal x-ray uses a very ... of an abdominal x-ray? What is abdominal x-ray? An x-ray (radiograph) is a noninvasive medical ...

  3. 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

  4. Theoretical Calculations and Simulations of Interaction of X-Rays with High-Z Nanomoities for Use in Cancer Radiotherapy

    Science.gov (United States)

    Lim, Sara N.; Pradhan, Anil K.; Nahar, Sultana N.

    2013-06-01

    When used with X-ray radiotherapy, heavy elements (high atomic number Z or HZ) such as gold(Au) and platinum(Pt) have the potential to greatly sensitize and enhance the damage to tumor tissues. While HZ radiosensitization has been shown to be higly effective in reducing tumor sizes, much work still needs to be done to determine the ideal X-ray energy/energy spectrum. The likelihood of photoelectric absorption of X-rays that result in the production of cell-killing Auger electrons relative to the photon scatter in an HZ sensitized tumor has to be determined for treatments using X-rays from various sources and energies to assess their efficacy. In this report, we present computations that outline the dependence of photoelectric absorption on X-ray energy. The relative X-ray absorption by a radiosensitized tumor was calculated to contrast the efficacy of different X-ray sources in Auger electron production at different tumor depths. Enhanced photoabsorption of low-energy X-rays from broadband sources in the keV range is shown to be much higher than from those in the MeV range. In addition, with the use of the Monte Carlo code package Geant4, we present the total X-ray energy deposited into a radiosensitized tumor located at different depths in a phantom. The enhancement in radiation dose deposition will also be analysed at the microscopic cellular level to determine the HZ radiosensitizer concentration required. Potential use of monochromatic X-rays for more precise HZ radiosensitization will also be described.

  5. The X-ray Power Density Spectrum of the Seyfert 2 Galaxy NGC 4945: Analysis and Application of the Method of Light Curve Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Martin; /SLAC

    2010-12-16

    The study of the power density spectrum (PDS) of fluctuations in the X-ray flux from active galactic nuclei (AGN) complements spectral studies in giving us a view into the processes operating in accreting compact objects. An important line of investigation is the comparison of the PDS from AGN with those from galactic black hole binaries; a related area of focus is the scaling relation between time scales for the variability and the black hole mass. The PDS of AGN is traditionally modeled using segments of power laws joined together at so-called break frequencies; associations of the break time scales, i.e., the inverses of the break frequencies, with time scales of physical processes thought to operate in these sources are then sought. I analyze the Method of Light Curve Simulations that is commonly used to characterize the PDS in AGN with a view to making the method as sensitive as possible to the shape of the PDS. I identify several weaknesses in the current implementation of the method and propose alternatives that can substitute for some of the key steps in the method. I focus on the complications introduced by uneven sampling in the light curve, the development of a fit statistic that is better matched to the distributions of power in the PDS, and the statistical evaluation of the fit between the observed data and the model for the PDS. Using archival data on one AGN, NGC 3516, I validate my changes against previously reported results. I also report new results on the PDS in NGC 4945, a Seyfert 2 galaxy with a well-determined black hole mass. This source provides an opportunity to investigate whether the PDS of Seyfert 1 and Seyfert 2 galaxies differ. It is also an attractive object for placement on the black hole mass-break time scale relation. Unfortunately, with the available data on NGC 4945, significant uncertainties on the break frequency in its PDS remain.

  6. Suzaku view of Be/X-ray binary pulsar GX 304-1 during Type I X-ray outbursts

    CERN Document Server

    Jaisawal, Gaurava K; Epili, Prahlad

    2016-01-01

    We report the timing and spectral properties of Be/X-ray binary pulsar GX 304-1 by using two Suzaku observations during its 2010 August and 2012 January X-ray outbursts. Pulsations at ~275 s were clearly detected in the light curves from both the observations. Pulse profiles were found to be strongly energy-dependent. During 2010 observation, prominent dips seen in soft X-ray ($\\leq$10 keV) pulse profiles were found to be absent at higher energies. However, during 2012 observation, the pulse profiles were complex due to the presence of several dips. Significant changes in the shape of the pulse profiles were detected at high energies ($>$35 keV). A phase shift of $\\sim$0.3 was detected while comparing the phase of main dip in pulse profiles below and above $\\sim$35 keV. Broad-band energy spectrum of pulsar was well described by a partially absorbed Negative and Positive power-law with Exponential cutoff (NPEX) model with 6.4 keV iron line and a cyclotron absorption feature. Energy of cyclotron absorption line...

  7. NuSTAR and XMM-Newton observations of the extreme ultraluminous X-ray source NGC 5907 ULX1: A Vanishing Act

    CERN Document Server

    Walton, D J; Bachetti, M; Barret, D; Boggs, S E; Christensen, F E; Craig, W W; Fuerst, F; Grefenstette, B W; Hailey, C J; Madsen, K K; Middleton, M J; Rana, V; Roberts, T P; Stern, D; Sutton, A D; Webb, N; Zhang, W

    2014-01-01

    We present results obtained from two broadband X-ray observations of the extreme ultraluminous X-ray source (ULX) NGC5907 ULX1, known to have a peak X-ray luminosity of ~5e40 erg/s. These XMM-Newton and NuSTAR observations, separated by only ~4 days, revealed an extreme level of short-term flux variability. In the first epoch, NGC5907 ULX1 was undetected by NuSTAR, and only weakly detected (if at all) with XMM-Newton, while in the second NGC5907 ULX1 was clearly detected at high luminosity by both missions. This implies an increase in flux of ~2 orders of magnitude or more during this ~4 day window. We argue that this is likely due to a rapid rise in the mass accretion rate, rather than to a transition from an extremely obscured to an unobscured state. During the second epoch we observed the broadband 0.3-20.0 keV X-ray luminosity to be (1.55+/-0.06)e40 erg/s, similar to the majority of the archival X-ray observations. The broadband X-ray spectrum obtained from the second epoch is inconsistent with the low/ha...

  8. 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)

  9. Medical X-Rays

    Science.gov (United States)

    ... The Conference of Radiation Control Program Directors (CRCPD) publishes Suggested State Regulations for the Control of Radiation , ... eSubmitter Guidance for Industry and Food and Drug Administration Staff - Assembler's Guide to Diagnostic X-Ray Equipment ...

  10. Chest X-Ray

    Medline Plus

    Full Text Available ... However, it’s important to consider the likelihood of benefit to your health. While a chest x-ray use a tiny dose of ionizing radiation, the benefit of an accurate diagnosis far outweighs any risk. ...

  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. Ten years of X-ray interferometry

    International Nuclear Information System (INIS)

    X-ray interferometers were the first optical instruments which utilized many Bragg reflecting components in monolithic blocks of perfect crystal. They have made important contributions to our knowledge of fundamental constants, of Bragg reflection x-ray optics, of strains and defects in crystals and of the optical constants of materials in the x-ray region of the electromagnetic spectrum. Based on an oversimplified optical analogue, their mode of operation is described in detail. Current applications of crystal interferometers and future work is briefly reviewed. (author)

  13. BROADBAND JET EMISSION IN YOUNG AND POWERFUL RADIO SOURCES: THE CASE OF THE COMPACT STEEP SPECTRUM QUASAR 3C 186

    International Nuclear Information System (INIS)

    We present the X-ray analysis of a deep (∼200 ks) Chandra observation of the compact steep spectrum radio-loud quasar 3C 186 (z = 1.06) and investigate the contribution of the unresolved radio jet to the total X-ray emission. The spectral analysis is not conclusive on the origin of the bulk of the X-ray emission. In order to examine the jet contribution to the X-ray flux, we model the quasar spectral energy distribution, adopting several scenarios for the jet emission. For the values of the main physical parameters favored by the observables, a dominant role of the jet emission in the X-ray band is ruled out when a single-zone (leptonic) scenario is adopted, even including the contribution of the external photon fields as seed photons for inverse Compton emission. We then consider a structured jet, with the blazar component that—although not directly visible in the X-ray band—provides an intense field of seed synchrotron photons Compton-scattered by electrons in a mildly relativistic knot. In this case, the whole X-ray emission can be accounted for if we assume a blazar luminosity within the range observed from flat spectrum radio quasars. The X-ray radiative efficiency of such a (structured) jet is intimately related to the presence of a complex velocity structure. The jet emission can provide a significant contribution in X-rays if it decelerates within the host galaxy on kiloparsec scales. We discuss the implications of this model in terms of jet dynamics and interaction with the ambient medium.

  14. BROADBAND JET EMISSION IN YOUNG AND POWERFUL RADIO SOURCES: THE CASE OF THE COMPACT STEEP SPECTRUM QUASAR 3C 186

    Energy Technology Data Exchange (ETDEWEB)

    Migliori, Giulia; Siemiginowska, Aneta [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Celotti, Annalisa, E-mail: migliori@cfa.harvard.edu [SISSA, Via Bonomea 265, I-34136 Trieste (Italy)

    2012-04-20

    We present the X-ray analysis of a deep ({approx}200 ks) Chandra observation of the compact steep spectrum radio-loud quasar 3C 186 (z = 1.06) and investigate the contribution of the unresolved radio jet to the total X-ray emission. The spectral analysis is not conclusive on the origin of the bulk of the X-ray emission. In order to examine the jet contribution to the X-ray flux, we model the quasar spectral energy distribution, adopting several scenarios for the jet emission. For the values of the main physical parameters favored by the observables, a dominant role of the jet emission in the X-ray band is ruled out when a single-zone (leptonic) scenario is adopted, even including the contribution of the external photon fields as seed photons for inverse Compton emission. We then consider a structured jet, with the blazar component that-although not directly visible in the X-ray band-provides an intense field of seed synchrotron photons Compton-scattered by electrons in a mildly relativistic knot. In this case, the whole X-ray emission can be accounted for if we assume a blazar luminosity within the range observed from flat spectrum radio quasars. The X-ray radiative efficiency of such a (structured) jet is intimately related to the presence of a complex velocity structure. The jet emission can provide a significant contribution in X-rays if it decelerates within the host galaxy on kiloparsec scales. We discuss the implications of this model in terms of jet dynamics and interaction with the ambient medium.

  15. 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 ...

  16. Parametric X-rays at FAST

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Tanaji [Fermilab

    2016-06-01

    We discuss the generation of parametric X-rays (PXR) in the photoinjector at the new FAST facility at Fermilab. Detailed calculations of the intensity spectrum, energy and angular widths and spectral brilliance with a diamond crystal are presented. We also report on expected results with PXR generated while the beam is channeling. The low emittance electron beam makes this facility a promising source for creating brilliant X-rays.

  17. Modeling and characterization of X-ray yield in a polychromatic, lab-scale, X-ray computed tomography system

    International Nuclear Information System (INIS)

    A modular X-ray computed micro-tomography (µXCT) system is characterized in terms of X-ray yield resulting both from the generated X-ray spectrum and from X-ray detection with an energy-sensitive detector. The X-ray computed tomography system is composed of a commercially available cone-beam microfocus X-ray source and a modular optically-coupled-CCD-scintillator X-ray detector. The X-ray yield is measured and reported in units independent from exposure time, X-ray tube beam target current, and cone-beam-to-detector geometry. The polychromatic X-ray source is modeled as a broad Bremsstrahlung X-ray spectrum in order to understand the effect of the controllable parameters, that is, X-ray tube accelerating voltage and X-ray beam filtering. An approach is adopted which expresses the absolute number of emitted X-rays. The response of the energy-sensitive detector to the modeled spectrum is modeled as a function of scintillator composition and thickness. The detection efficiency model for the polychromatic X-ray detector considers the response of the light collection system and the electronic imaging array in order to predict absolute count yield under the studied conditions. The modeling approach is applied to the specific hardware implemented in the current µXCT system. The model's predictions for absolute detection rate are in reasonable agreement with measured values under a range of conditions applied to the system for X-ray microtomography imaging, particularly for the LuAG:Ce scintillator material

  18. Modeling and characterization of X-ray yield in a polychromatic, lab-scale, X-ray computed tomography system

    Energy Technology Data Exchange (ETDEWEB)

    Mertens, J.C.E.; Chawla, Nikhilesh, E-mail: nchawla@asu.edu

    2015-05-21

    A modular X-ray computed micro-tomography (µXCT) system is characterized in terms of X-ray yield resulting both from the generated X-ray spectrum and from X-ray detection with an energy-sensitive detector. The X-ray computed tomography system is composed of a commercially available cone-beam microfocus X-ray source and a modular optically-coupled-CCD-scintillator X-ray detector. The X-ray yield is measured and reported in units independent from exposure time, X-ray tube beam target current, and cone-beam-to-detector geometry. The polychromatic X-ray source is modeled as a broad Bremsstrahlung X-ray spectrum in order to understand the effect of the controllable parameters, that is, X-ray tube accelerating voltage and X-ray beam filtering. An approach is adopted which expresses the absolute number of emitted X-rays. The response of the energy-sensitive detector to the modeled spectrum is modeled as a function of scintillator composition and thickness. The detection efficiency model for the polychromatic X-ray detector considers the response of the light collection system and the electronic imaging array in order to predict absolute count yield under the studied conditions. The modeling approach is applied to the specific hardware implemented in the current µXCT system. The model's predictions for absolute detection rate are in reasonable agreement with measured values under a range of conditions applied to the system for X-ray microtomography imaging, particularly for the LuAG:Ce scintillator material.

  19. Complex X-ray Absorption and the Fe Kalpha Profile in NGC 3516

    CERN Document Server

    Turner, T J; George, I M; Reeves, J N; Bottorff, M C

    2004-01-01

    We present data from simultaneous Chandra, XMM-Newton and BeppoSAX observations of the Seyfert 1 galaxy NGC 3516, taken during 2001 April and Nov. We have investigated the nature of the very flat observed X-ray spectrum. Chandra grating data show the presence of X-ray absorption lines, revealing two distinct components of the absorbing gas, one which is consistent with our previous model of the UV/X-ray absorber while the other, which is outflowing at a velocity of ~1100 km/s has a larger column density and is much more highly ionized. The broad-band spectral characteristics of the X-ray continuum observed with XMM during 2001 April, reveal the presence of a third layer of absorption consisting of a very large column (~2.5 x 10E23 cm^-2) of highly ionized gas with a covering fraction ~50%. This low covering fraction suggests that the absorber lies within a few lt-days of the X-ray source and/or is filamentary in structure. Interestingly, these absorbers are not in thermal equilibrium with one another. The two...

  20. 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.

  1. 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...

  2. Unveiling the hard X-ray spectrum from the "burst-only" source SAX J1753.5-2349 in outburst

    CERN Document Server

    Del Santo, Melania; Romano, Patrizia; Bazzano, Angela; Wijnands, Rudy; Degenaar, Nathalie; Mereghetti, Sandro

    2010-01-01

    Discovered in 1996 by BeppoSAX during a single type-I burst event, SAX J1753.5-2349 was classified as "burst-only" source. Its persistent emission, either in outburst or in quiescence, had never been observed before October 2008, when SAX J1753.5-2349 was observed for the first time in outburst. Based on INTEGRAL observations,we present here the first high-energy emission study (above 10 keV) of a so-called "burst-only". During the outburst the SAX J1753.5-2349 flux decreased from 10 to 4 mCrab in 18-40 keV, while it was found being in a constant low/hard spectral state. The broad-band (0.3-100 keV) averaged spectrum obtained by combining INTEGRAL/IBIS and Swift/XRT data has been fitted with a thermal Comptonisation model and an electron temperature >24 keV inferred. However, the observed high column density does not allow the detection of the emission from the neutron star surface. Based on the whole set of observations of SAX J1753.5-2349, we are able to provide a rough estimate of the duty cycle of the sys...

  3. X-ray Variability of AGN and the Flare Model

    OpenAIRE

    Goosmann, R. W.; Czerny, B.; Dumont, A. -M.; Mouchet, M.; Rozanska, A.

    2004-01-01

    Short-term variability of X-ray continuum spectra has been reported for several Active Galactic Nuclei. Significant X-ray flux variations are observed within time scales down to 10^3-10^5 seconds. We discuss short variability time scales in the frame of the X-ray flare model, which assumes the release of a large hard X-ray flux above a small portion of the accretion disk. The resulting observed X-ray spectrum is composed of the primary radiation and of a reprocessed Compton reflection compone...

  4. CRL X-RAY TUBE

    OpenAIRE

    Kolchevsky, N. N.; Petrov, P. V.

    2015-01-01

    A novel types of X-ray tubes with refractive lenses are proposed. CRL-R X-ray tube consists of Compound Refractive Lens- CRL and Reflection X-ray tube. CRL acts as X-ray window. CRL-T X-ray consists of CRL and Transmission X-ray tube. CRL acts as target for electron beam. CRL refractive lens acts as filter, collimator, waveguide and focusing lens. Properties and construction of the CRL X-ray tube are discussed.

  5. Measurement of specifications of x-ray quality for calibration

    International Nuclear Information System (INIS)

    The filtered continuous X-rays are often used for the calibration and measurement of the energy response of γ-ray dosemeter and dose ratemeter. These X-rays are easily made and sufficiently available for the measurement which does not require the strictly monoenergetic X-ray beam. It is necessary for the employment of continuous X-rays to specify the X-ray qualities such as representative energy and degree of filtration. This report describes a measurement of some specifications of the X-ray quality for a X-ray generator with 50 -- 120 kV of tube potential and a comparison between existing and ISO-4037 proposing expressions on the X-ray quality. According to the resolution of X-ray spectrum, we made four different X-ray quality sets : Wide, Middle, Narrow, and Extra-narrow spectrum series. The information described here about the filtered X-rays will be of use for the calibration and measurement of energy response of the health physics instruments. (J.P.N.)

  6. Chest X-Ray

    Medline Plus

    Full Text Available ... this Site RadiologyInfo.org is produced by: Image/Video Gallery Your radiologist explains chest x-ray. Transcript ... time! Spotlight Recently posted: Pediatric MRI Intravascular Ultrasound Video: Chest CT Video:Thyroid Ultrasound Video: Head CT ...

  7. Chest X-Ray

    Medline Plus

    Full Text Available ... Pediatric Ultrasound Video: Angioplasty & vascular stenting Video: Arthrography Radiology and You About this Site RadiologyInfo.org is ... radiologist explains chest x-ray. Transcript Welcome to Radiology Info dot org! Hello, I’m Dr. Geoffrey ...

  8. Chest X-Ray

    Medline Plus

    Full Text Available ... this Site RadiologyInfo.org is produced by: Image/Video Gallery Your radiologist explains chest x-ray. Transcript ... Recently posted: Focused Ultrasound for Uterine Fibroids Dementia Video: General Ultrasound Video: Pediatric Nuclear Medicine Radiology and ...

  9. Medical x-ray

    International Nuclear Information System (INIS)

    This book describes the fundamental subject about medical radiography. It is a multidisciplinary field that requires cross professional input from scientists, engineers and medical doctors. However, it is presented in simple language to suit different levels of readers from x-ray operators and radiographers to physists, general practitioners and radiology specialists.The book is written in accordance to the requirements of the standard syllabus approved by the Ministry of Health Malaysia for the training of medical x-ray operator and general practitioners. In general, the content is not only designed to provide relevant and essential subject for related professionals in medical radiological services such as x-ray operator, radiographer and radiologists, but also to address those in associated radiological services including nurses, medical technologists and physicists.The book is organized and arranged sequentially into 3 parts for easy reference: Radiation safety; X-ray equipment and associated facilities; Radiography practices. With proper grasping of all these parts, the radiological services could be provided with confident and the highest professional standard. Thus, medical imaging with highest quality that can provide useful diagnostic information at minimum doses and at cost effective could be assured

  10. Energy resolved X-ray grating interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Thuering, T.; Stampanoni, M. [Swiss Light Source, Paul Scherrer Institut, Villigen PSI (Switzerland); Institute for Biomedical Engineering, Swiss Federal Institute of Technology, Zurich (Switzerland); Barber, W. C.; Iwanczyk, J. S. [DxRay, Inc., Northridge, California 91324 (United States); Seo, Y.; Alhassen, F. [UCSF Physics Research Laboratory, Department of Radiology and Biomedical Imaging, University of California, San Francisco, California 94143 (United States)

    2013-05-13

    Although compatible with polychromatic radiation, the sensitivity in X-ray phase contrast imaging with a grating interferometer is strongly dependent on the X-ray spectrum. We used an energy resolving detector to quantitatively investigate the dependency of the noise from the spectral bandwidth and to consequently optimize the system-by selecting the best energy band matching the experimental conditions-with respect to sensitivity maximization and, eventually, dose. Further, since theoretical calculations of the spectrum are usually limited due to non-ideal conditions, an energy resolving detector accurately quantifies the spectral changes induced by the interferometer including flux reduction and beam hardening.

  11. X-ray Spectral Variation of Eta Carinae through the 2003 X-ray Minimum

    CERN Document Server

    Hamaguchi, K; Gull, T; Ishibashi, K; Pittard, J M; Hillier, D J; Damineli, A; Davidson, K; Nielsen, K E; Kober, G V; Hamaguchi, Kenji; Corcoran, Michael F.; Gull, Theodore; Ishibashi, Kazunori; Pittard, Julian M.; Damineli, Augusto; Davidson, Kris; Nielsen, Krister E.; Kober, Gladys Vieira

    2007-01-01

    We report the results of an X-ray observing campaign on the massive, evolved star Eta Carinae, concentrating on the 2003 X-ray minimum as seen by the XMM-Newton observatory. These are the first spatially-resolved X-ray monitoring observations of the stellar X-ray spectrum during the minimum. The hard X-ray emission, believed to be associated with the collision of Eta Carinae's wind with the wind from a massive companion star, varied strongly in flux on timescales of days, but not significantly on timescales of hours. The lowest X-ray flux in the 2-10 keV band seen by XMM-Newton was only 0.7% of the maximum seen by RXTE just before the X-ray minimum. The slope of the X-ray continuum above 5 keV did not vary in any observation, which suggests that the electron temperature of the hottest plasma associated with the stellar source did not vary significantly at any phase. Through the minimum, the absorption to the stellar source increased by a factor of 5-10 to NH ~3-4E23 cm-2. The thermal Fe XXV emission line show...

  12. Studies of soft x-ray emission during solar flares

    International Nuclear Information System (INIS)

    Solar flare soft x-ray emission from 0.5 A to 8.5 A was observed during 1967-68 by Bragg crystal (LiF and EDDT) spectrometers aboard the OSO-4 satellite and also by NRL broad-band ionization detectors aboard the OGO-4 satellite. In this work, instrumental parameters for the LiF crystal spectrometer based on experimental values have been determined and used in the data analysis. The total continuum emission in the 0.5 to 3 A and the 1 to 8 A broad band segments has been determined from OGO-4 data for 21 flares. In doing this, a simple and approximate method of converting the total emission based on the gray body approximation (in which the OGO-4 data are reported) to one based on the thermal continuum spectrum has been developed. (author)

  13. Pyroelectric x-ray detectors and x-ray pyrometers

    International Nuclear Information System (INIS)

    This paper discusses pyroelectric detectors which are very promising x-ray detectors for intense pulsed x-ray/γ-ray measurements and can be used as x-ray pyrometers. They are fast, passive, and inherently flat in spectral response for low energy x-rays. The authors report tests of LiTaO3, Sr.5Ba.5Nb2O6 and LiNbO3 detectors at Nova laser with 1 ns low energy x-rays and at Zapp Z-pinch machine with 100 ns x-rays. The temporal and spectral responses are discussed

  14. Pyroelectric x-ray detectors and x-ray pyrometers

    International Nuclear Information System (INIS)

    Pyroelectric detectors are very promising x-ray detectors for intense pulsed x-ray/γ-ray measurements and can be used as x-ray pyrometers. They are fast, passive, and inherently flat in spectral response for low-energy x rays. We report our tests of LiTaO3 detectors at Nova laser with 1-ns low-energy x rays and at Zapp Z-pinch machine with 100-ns x rays. The temporal and spectral responses are discussed

  15. Soft X-ray Calibration of the Co/C Multilayer Mirrors for the Objective Crystal Spectrometer on the Spectrum Röntgen-Gamma Satellite

    DEFF Research Database (Denmark)

    Abdali, Salim; Tarrio, C.; Christensen, Finn Erland;

    1996-01-01

    , the reflectivity performance as a function of energy and angle of incidence of all crystals has been measured using line radiation from an x-ray tube which provides 1.487 keV and 0.277 keV and using synchrotron radiation from 0.16 keV to 0.28 keV at the Synchrotron Ultraviolet Radiation electron storage ring a t...

  16. Backscatter, anisotropy, and polarization of solar hard X-rays

    Science.gov (United States)

    Bai, T.; Ramaty, R.

    1978-01-01

    The problems of anisotropy, polarization, center-to-limb variation of the X-ray spectrum, and Compton backscatter are investigated in a study of solar hard X-rays. Effect of backscatter are found particularly important for anisotropic sources which emit hard X-rays predominantly toward the photosphere; for such anisotropic primary X-ray sources, the observed X-ray flux near 30 keV does not depend significantly on the position of the flare. In addition, the degree of polarization of the sum of the primary and reflected X-rays with energies in the 15 to 30 keV range may be as high as 30%. Determination of the height and anisotropy of the primary X-ray sources from study of the albedo patch is also discussed.

  17. Black Holes in Ultra-Luminous X-ray sources: X-ray timing versus spectroscopy

    CERN Document Server

    Caballero-Garcia, M D; Belloni, T M; Wolter, A

    2012-01-01

    Ultra-Luminous X-ray sources are accreting black holes that might represent strong evidence of the Intermediate Mass Black Holes (IMBH), proposed to exist by theoretical studies but with no firm detection (as a class) so far. We analyze the best X-ray timing and spectral data from the ULX in NGC 5408 provided by XMM-Newton. The main goal is to study the broad-band noise variability of the source. We found an anti-correlation of the fractional root-mean square variability versus the intensity of the source, similar to black-hole binaries during hard states.

  18. Characterization of an indirect X-ray imaging detector by simulation and experiment.

    Science.gov (United States)

    Doshi, C; van Riessen, G; Balaur, E; de Jonge, M D; Peele, A G

    2015-01-01

    We describe a comprehensive model of a commercial indirect X-ray imaging detector that accurately predicts the detector point spread function and its dependence on X-ray energy. The model was validated by measurements using monochromatic synchrotron radiation and extended to polychromatic X-ray sources. Our approach can be used to predict the performance of an imaging detector and can be used to optimize imaging experiments with broad-band X-ray sources. PMID:25203971

  19. Achievement of Narrow-Band CARS Signal by Manipulating Broad-band Laser Spectrum

    International Nuclear Information System (INIS)

    We theoretically demonstrate the achievement of narrow-band coherent anti-Stokes Raman scattering (CARS) signal by manipulating broad-band probe spectrum. The narrowing of the CARS signal depends on the spectrum bandwidth of the probe beam, and thus high-resolution CARS signal for a complicated quantum system can be obtained by the simple spectrum manipulation. Furthermore, the energy-level diagram for the complicated quantum system can also be labelled by measuring the CARS signal at a given frequency. (fundamental areas of phenomenology (including applications))

  20. 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.

  1. X-ray diffraction

    International Nuclear Information System (INIS)

    We have been interested in structural elucidation by x-ray diffraction of compounds of biological interest. Understanding exactly how atoms are arranged in three-dimensional arrays as molecules can help explain the relationship between structure and functions. The species investigated may vary in size and shape; our recent studies included such diverse substances as antischistosomal drugs, a complex of cadmium with nucleic acid base, nitrate salts of adenine, and proteins

  2. Status Of The Development Of A Thin Foil High Throughput X-Ray Telescope For The Soviet Spectrum X-Gamma Mission

    DEFF Research Database (Denmark)

    WESTERGAARD, NJ; BYRNAK, BP; Christensen, Finn Erland;

    1989-01-01

    modification of this design is optimized with respect to high energy throughput of the telescope. The mechanical design and the status of the surface preparation technologies are described. Various X-ray and optical test facilities for the measurement of surface roughness, "orange peel", and figure errors...... are described. An optical parallel beam has been established and results from the first mounted mirrors are discussed. The design goal is an angular resolution of 2 arcminutes (HEW). The first results seem to indicate that this is feasible and the possibility of going down to 1.5 arcminutes exits....

  3. Broad-band modelling of short gamma-ray bursts with energy injection from magnetar spin-down and its implications for radio detectability

    NARCIS (Netherlands)

    B.P. Gompertz; A.J. van der Horst; P.T. O'Brien; G.A. Wynn; K. Wiersema

    2015-01-01

    The magnetar model has been proposed to explain the apparent energy injection in the X-ray light curves of short gamma-ray bursts (SGRBs), but its implications across the full broad-band spectrum are not well explored. We investigate the broad-band modelling of four SGRBs with evidence for energy in

  4. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... wrist, arm, elbow, shoulder, spine, pelvis, hip, thigh, knee, leg (shin), ankle or foot. top of page ... the patient standing upright, as in cases of knee x-rays. A portable x-ray machine is ...

  5. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... images for evaluation. National and international radiology protection organizations continually review and update the technique standards used by radiology professionals. Modern x-ray systems have very controlled x-ray beams and dose ...

  6. 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 ( ...

  7. 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? ... top of page What are the benefits vs. risks? Benefits Bone x-rays are the fastest and ...

  8. Dental X-ray apparatus

    International Nuclear Information System (INIS)

    Intra-oral dental X-ray apparatus for panoramic radiography is described in detail. It comprises a tubular target carrier supporting at its distal end a target with an inclined forward face. Image definition is improved by positioning in the path of the X-rays a window of X-ray transmitting ceramic material, e.g. 90% oxide of Be, or Al, 7% Si02. The target carrier forms a probe which can be positioned in the patient's mouth. X-rays are directed forwardly and laterally of the target to an X-ray film positioned externally. The probe is provided with a detachable sleeve having V-form arms of X-ray opaque material which serve to depress the tongue out of the radiation path and also shield the roof of the mouth and other regions of the head from the X-ray pattern. A cylindrical lead shield defines the X-ray beam angle. (author)

  9. 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 ...

  10. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... As a result, bones appear white on the x-ray, soft tissue shows up in shades of gray and air appears black. Until recently, x-ray images were maintained on large film sheets (much ...

  11. 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 ... a large photographic negative). Today, most images are digital files that are stored electronically. These stored images ...

  12. Broadband high-efficiency dielectric metasurfaces for the visible spectrum.

    Science.gov (United States)

    Devlin, Robert C; Khorasaninejad, Mohammadreza; Chen, Wei Ting; Oh, Jaewon; Capasso, Federico

    2016-09-20

    Metasurfaces are planar optical elements that hold promise for overcoming the limitations of refractive and conventional diffractive optics. Original dielectric metasurfaces are limited to transparency windows at infrared wavelengths because of significant optical absorption and loss at visible wavelengths. Thus, it is critical that new materials and nanofabrication techniques be developed to extend dielectric metasurfaces across the visible spectrum and to enable applications such as high numerical aperture lenses, color holograms, and wearable optics. Here, we demonstrate high performance dielectric metasurfaces in the form of holograms for red, green, and blue wavelengths with record absolute efficiency (>78%). We use atomic layer deposition of amorphous titanium dioxide with surface roughness less than 1 nm and negligible optical loss. We use a process for fabricating dielectric metasurfaces that allows us to produce anisotropic, subwavelength-spaced dielectric nanostructures with shape birefringence. This process is capable of realizing any high-efficiency metasurface optical element, e.g., metalenses and axicons. PMID:27601634

  13. X-ray optics for axion helioscopes

    DEFF Research Database (Denmark)

    Jakobsen, Anders Clemen; Pivovaroff, Michael J.; Christensen, Finn Erland

    2013-01-01

    A method of optimizing grazing incidence x-ray coatings in ground based axion helioscopes is presented. Software has been been developed to find the optimum coating when taking both axion spectrum and Micromegas detector quantum efficiency into account. A comparison of the relative effective area...... of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only....

  14. Fourier techniques in X-ray timing

    NARCIS (Netherlands)

    M. van der Klis

    1988-01-01

    Basic principles of Fourier techniques often used in X-ray time series analysis are reviewed. The relation between the discrete Fourier transform and the continuous Fourier transform is discussed to introduce the concepts of windowing and aliasing. The relation is derived between the power spectrum

  15. Weak soft X-ray excesses need not result from the high-frequency tail of the optical/ultraviolet bump in active galactic nuclei

    Science.gov (United States)

    Czerny, Bozena; Zycki, Piotr T.

    1994-01-01

    The broad-band ROSAT/EXOSAT X-ray spectra of six Seyfert 1 galaxies are fitted by a model consisting of a direct power law and a component due to reflection/reprocessing from a partially ionized, optically thick medium. The reflected spectrum contains emission features from various elements in the soft X-ray range. In all objects but one (Mrk 335), the fit is satisfactory, and no additional soft X-ray excess is required by the data. This means that in most sources there is no need for the thermal 'big blue bumps' to extend into soft X-rays, and the soft X-ray excesses reported previously can be explained by reflection/reprocessing. Satisfactory fits are obtained for a medium ionized by a source radiating at less than or approximately 15% of the Eddington rate. The fits require that the reflection is enhanced relative to an isotropically emitting source above a flat disk. The necessary high effectiveness of reflection in the soft X-ray band requires strong soft thermal flux dominating over hard X-rays.

  16. Dynamical Ne K Edge and Line Variations in the X-Ray Spectrum of the Ultra-compact Binary 4U 0614+091

    CERN Document Server

    Schulz, Norbert S; Chakrabarty, Deepto; Canizares, Claude R

    2010-01-01

    We observed the ultra-compact binary candidate 4U 0614+091 for a total of 200 ksec with the high-energy transmission gratings onboard the \\chandra X-ray Observatory. The source is found at various intensity levels with spectral variations present. X-ray luminosities vary between 2.0$\\times10^{36}$ \\ergsec and 3.5$\\times10^{36}$ \\ergsec. Continuum variations are present at all times and spectra can be well fit with a powerlaw component, a high kT blackbody component, and a broad line component near oxygen. The spectra require adjustments to the Ne K edge and in some occasions also to the Mg K edge. The Ne K edge appears variable in terms of optical depths and morphology. The edge reveals average blue- and red-shifted values implying Doppler velocities of the order of 3500 \\kms. The data show that Ne K exhibits excess column densities of up to several 10$^{18}$ cm$^{-2}$. The variability proves that the excess is intrinsic to the source. The correponding disk velocities also imply an outer disk radius of the or...

  17. 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.

  18. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... x-rays. top of page What does the equipment look like? The equipment typically used for bone x-rays consists of ... and joint abnormalities, such as arthritis. X-ray equipment is relatively inexpensive and widely available in emergency ...

  19. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... The x-ray tube is connected to a flexible arm that is extended over the patient while an x-ray film holder or image recording plate is placed beneath the patient. top of page How does the procedure work? X-rays are a form of radiation like ...

  20. Tunable X-ray source

    Science.gov (United States)

    Boyce, James R.

    2011-02-08

    A method for the production of X-ray bunches tunable in both time and energy level by generating multiple photon, X-ray, beams through the use of Thomson scattering. The method of the present invention simultaneously produces two X-ray pulses that are tunable in energy and/or time.

  1. 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...

  2. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... lies. A drawer under the table holds the x-ray film or image recording plate . Sometimes the x-ray ... that is extended over the patient while an x-ray film holder or image recording plate is placed beneath ...

  3. X-Ray Exam: Ankle

    Science.gov (United States)

    ... Tropical Delight: Melon Smoothie Pregnant? Your Baby's Growth X-Ray Exam: Ankle KidsHealth > For Parents > X-Ray Exam: Ankle Print A A A Text Size ... español Radiografía: tobillo What It Is An ankle X-ray is a safe and painless test that uses ...

  4. X-Ray Exam: Finger

    Science.gov (United States)

    ... Tropical Delight: Melon Smoothie Pregnant? Your Baby's Growth X-Ray Exam: Finger KidsHealth > For Parents > X-Ray Exam: Finger Print A A A Text Size ... español Radiografía: dedo What It Is A finger X-ray is a safe and painless test that uses ...

  5. X-Ray Exam: Wrist

    Science.gov (United States)

    ... Tropical Delight: Melon Smoothie Pregnant? Your Baby's Growth X-Ray Exam: Wrist KidsHealth > For Parents > X-Ray Exam: Wrist Print A A A Text Size ... español Radiografía: muñeca What It Is A wrist X-ray is a safe and painless test that uses ...

  6. X-Ray Exam: Hip

    Science.gov (United States)

    ... Tropical Delight: Melon Smoothie Pregnant? Your Baby's Growth X-Ray Exam: Hip KidsHealth > For Parents > X-Ray Exam: Hip Print A A A Text Size ... español Radiografía: cadera What It Is A hip X-ray is a safe and painless test that uses ...

  7. X-Ray Exam: Forearm

    Science.gov (United States)

    ... Tropical Delight: Melon Smoothie Pregnant? Your Baby's Growth X-Ray Exam: Forearm KidsHealth > For Parents > X-Ray Exam: Forearm Print A A A Text Size ... español Radiografía: brazo What It Is A forearm X-ray is a safe and painless test that uses ...

  8. X-Ray Exam: Pelvis

    Science.gov (United States)

    ... Tropical Delight: Melon Smoothie Pregnant? Your Baby's Growth X-Ray Exam: Pelvis KidsHealth > For Parents > X-Ray Exam: Pelvis Print A A A Text Size ... español Radiografía: pelvis What It Is A pelvis X-ray is a safe and painless test that uses ...

  9. X-Ray Exam: Foot

    Science.gov (United States)

    ... Tropical Delight: Melon Smoothie Pregnant? Your Baby's Growth X-Ray Exam: Foot KidsHealth > For Parents > X-Ray Exam: Foot Print A A A Text Size ... español Radiografía: pie What It Is A foot X-ray is a safe and painless test that uses ...

  10. Signatures of Accretion Shocks in Broadband Spectrum of Advective Flows Around Black Holes

    CERN Document Server

    Mandal, S; Mandal, Samir; Chakrabarti, Sandip K.

    2005-01-01

    We compute the effects of the centrifugal pressure supported shock waves on the emitted spectrum from an accretion disk primarily consisting of low angular momentum matter. Electrons are very efficiently accelerated by the accretion shock and acquire power-law distribution. The accelerated particles in turn emit synchrotron radiation in presence of a stochastic magnetic field in equipartition with the gas. Efficient cooling of the electrons by these soft photons reduces its temperature in comparison to the protons. We explore the nature of the broadband spectra by using Comptonization, bremsstrahlung and synchrotron emission. We then show that there could be two crossing points in a broadband spectrum, one near $\\sim 10 keV$ and the other $\\sim 300-400$KeV.

  11. Thermal X-ray emission from a baryonic jet: a self-consistent multicolour spectral model

    CERN Document Server

    Khabibullin, Ildar; Sazonov, Sergey

    2015-01-01

    We present a publicly-available spectral model for thermal X-ray emission from a baryonic jet in an X-ray binary system, inspired by the microquasar SS 433. The jet is assumed to be strongly collimated (half-opening angle $\\Theta\\sim 1\\deg$) and mildly relativistic (bulk velocity $\\beta=V_{b}/c\\sim 0.03-0.3$). Its X-ray spectrum is found by integrating over thin slices of constant temperature, radiating in optically thin coronal regime. The temperature profile along the jet and corresponding differential emission measure distribution are calculated with full account for gas cooling due to expansion and radiative losses. Since the model predicts both the spectral shape and luminosity of the jet's emission, its normalisation is not a free parameter if the source distance is known. We also explore the possibility of using simple X-ray observables (such as flux ratios in different energy bands) to constrain physical parameters of the jet (e.g. gas temperature and density at its base) without broad-band fitting of...

  12. Chandra X-ray spectroscopy of a clear dip in GX 13+1

    CERN Document Server

    D'Aì, A; Di Salvo, T; Riggio, A; Burderi, L; Robba, N R

    2014-01-01

    The source GX 13+1 is a persistent, bright Galactic X-ray binary hosting an accreting neutron star. It shows highly ionized absorption features, with a blueshift of $\\sim$ 400 km s$^{-1}$ and an outflow-mass rate similar to the accretion rate. Many other X-ray sources exhibit warm absorption features, and they all show periodic dipping behavior at the same time. Recently, a dipping periodicity has also been determined for GX 13+1 using long-term X-ray folded light-curves, leading to a clear identification of one of such periodic dips in an archival Chandra observation. We give the first spectral characterization of the periodic dip of GX 13+1 found in this archival Chandra observation performed in 2010. We used Chandra/HETGS data (1.0--10 keV band) and contemporaneous RXTE/PCA data (3.5--25 keV) to analyze the broadband X-ray spectrum. We adopted different spectral models to describe the continuum emission and used the XSTAR-derived warm absorber component to constrain the highly ionized absorption features. ...

  13. Rise and fall of the X-ray flash 080330: an off-axis jet?

    CERN Document Server

    Guidorzi, C; Kobayashi, S; Granot, J; Melandri, A; D'Avanzo, P; Kuin, N P M; Klotz, A; Fynbo, J P U; Covino, S; Greiner, J; Malesani, D; Mao, J; Mundell, C G; Steele, I A; Jakobsson, P; Margutti, R; Bersier, D; Campana, S; Chincarini, G; D'Elia, V; Fugazza, D; Genet, F; Gomboc, A; Kruehler, T; Yoldacs, A Kupcu; Moretti, A; Mottram, C J; O'Brien, P T; Smith, R J; Szokoly, G; Tagliaferri, G; Tanvir, N R; Gehrels, N

    2009-01-01

    X-ray flashes (XRFs) are a class of gamma-ray bursts (GRBs) with the peak energy of the time-integrated spectrum, Ep, below 30 keV, whereas classical GRBs have Ep of a few hundreds keV. Apart from Ep and the lower luminosity, the properties of XRFs are typical of the classical GRBs. Yet, the nature of XRFs and the differences from that of GRBs are not understood. In addition, there is no consensus on the interpretation of the shallow decay phase observed in most X-ray afterglows of both XRFs and GRBs. We examine in detail the case of XRF 080330 discovered by Swift at the redshift of 1.51. This burst is representative of the XRF class and exhibits an X-ray shallow decay. The rich and broadband (from NIR to UV) photometric data set we collected across this phase makes it an ideal candidate to test the off-axis jet interpretation proposed to explain both the softness of XRFs and the shallow decay phase. We present prompt gamma-ray, early and late IR/visible/UV and X-ray observations of the XRF 080330. We derive ...

  14. Suzaku Observation of Be/X-ray Binary Pulsar EXO 2030+375

    CERN Document Server

    Naik, Sachindra

    2014-01-01

    In this paper we study the timing and spectral properties of Be/X-ray binary pulsar EXO 2030+375 using a $Suzaku$ observation on 2012 May 23, during a less intense Type I outburst. Pulsations were clearly detected in the X-ray light curves at a barycentric period of 41.2852 s which suggests that the pulsar is spinning-up. The pulse profiles were found to be peculiar e.g. unlike that obtained from the earlier Suzaku observation on 2007 May 14. A single-peaked narrow profile at soft X-rays (0.5-10 keV range) changed to a double-peaked broad profile in 12-55 keV energy range and again reverted back to a smooth single-peaked profile at hard X-rays (55-70 keV range). The 1.0-100.0 keV broad-band spectrum of the pulsar was found to be well described by three continuum models such as (i) a partial covering high energy cut-off power-law model, (ii) a partially absorbed power-law with high-energy exponential rolloff and (iii) a partial covering Negative and Positive power law with EXponential (NPEX) continuum model. U...

  15. 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.)

  16. X-ray intensifying screens

    International Nuclear Information System (INIS)

    An x-ray intensifying screen comprises a support which has a luminescent composition comprising an isotropic phosphor and a polymer having an index of refraction within 0.02 of that of the phosphor over at least 80 percent of its emission spectrum. The support has an index of refraction up to or equal to 0.05 units higher than that of the phosphor and has a reflection optical density of at least 1.7 to light emitted by the phosphor. A preferred luminescent composition comprises Kl:Tl, Rbl:Tl at BaSrFCl:Eu mixed with two monomers such as 1-naphthylmethylmethacrylate, S(1-naphthylmethyl) thioacrylate, 1-bromo-2-naphthylacrylate, and benzyl methacrylate, coated on black anodised Al and polymerised in situ. The ratio of monomers is adjusted to give the desired refractive index. Other phosphors, polymers and supports are specified together with the preparation of the monomers and polymers. (author)

  17. X-ray scattering measurements from thin-foil x-ray mirrors

    DEFF Research Database (Denmark)

    Christensen, Finn Erland; BYRNAK, BP; Hornstrup, Allan;

    1992-01-01

    Thin foil X-ray mirrors are to be used as the reflecting elements in the telescopes of the X-ray satellites Spectrum-X-Gamma (SRG) and ASTRO-D. High resolution X-ray scattering measurements from the Au coated and dip-lacquered Al foils are presented. These were obtained from SRG mirrors positioned...... in a test quadrant of the telescope structure and from ASTRO-D foils held in a simple fixture. The X-ray data is compared with laser data and other surface structure data such as STM, atomic force microscopy (AFM), TEM, and electron micrography. The data obtained at Cu K-alpha(1), (8.05 keV) from all...

  18. GRB Redshift determination in the X-ray band

    OpenAIRE

    Campana, Sergio; Ghisellini, Gabriele; Lazzati, Davide; Haardt, Francesco; Covino, Stefano; .

    1999-01-01

    If gamma-ray bursts originate in dense stellar forming regions, the interstellar material can imprint detectable absorption features on the observed X-ray spectrum. Such features can be detected by existing and planned X-ray satellites, as long as the X-ray afterglow is observed after a few minutes from the burst. Detection of these X-ray features will make possible the determination of the redshift of gamma-ray bursts even when their optical afterglows are severely dimmed by extinction.

  19. eROSITA - Nearby Young Stars in X-rays

    CERN Document Server

    Robrade, Jan

    2015-01-01

    X-ray surveys are well suited to detect, identify and study young stars based on their high levels of magnetic activity and thus X-ray brightness. The eROSITA instrument onboard the Spectrum-Roentgen-Gamma (SRG) satellite will perform an X-ray all-sky survey that surpasses existing data by a sensitivity increase of more than an order of magnitude. The 4 yr survey is expected to detect more than half a million stars and stellar systems in X-rays.

  20. X-ray spectra for mamography

    International Nuclear Information System (INIS)

    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)

  1. Experimental device for the X-ray energetic distribution measurement in a tokamak plasma

    International Nuclear Information System (INIS)

    An experimental system to measure the X-ray spectrum in a tokamak plasma is described, emphasizing its characteristics: resolution, dead time and the pulse pile-up distortion effects on the X-ray spectra. (author)

  2. Broadband metasurfaces for anomalous transmission and spectrum splitting at visible frequencies

    Directory of Open Access Journals (Sweden)

    Li Zhongyang

    2015-01-01

    Full Text Available The emergent ultrathin metasurfaces are promising optical materials to enable novel photonic functionality and miniature optical devices. By elaborately design the interfacial phase shift from discrete nanoantennas with distinctive geometries, metasurfaces have the potential to shape desired wavefronts and arbitrary steer light propagation. However, the realization of broadband transmission-mode metasurfaces that operates at visible frequencies have still been significant challenging. Because it is difficult to achieve drastic broadband optical response depending on discrete plasmonic resonators and the fabrication of such subwavelength-size resonators with high uniformity is also challenging. Here, we propose an efficient yet a simple transmission-mode metasurface design comprising of a single, quasi-continuous nanoantenna as the build block. Each nanoantenna consist of a trapezoid-shaped triple-layered (Ag-SiO2-Ag plasmonic resonator which could induce drastic gradient phase shifts for transmitted light. We numerically demonstrated broadband (500–850 nm anomalous transmitted propagation and spectrum splitting at visible frequencies and beyond. The average power ratio of anomalous transmission mode to the first-order diffraction mode was calculated to be ~1000. Such proposed metasurface design is a clear departure from conventional metasurfaces utilizing multiple discrete resonators, and suggests applications for achieving ultrathin lenses, high SNR spectrometers, directional emitters and spectrum splitting surfaces for photovoltaics.

  3. THE XMM-NEWTON X-RAY SPECTRA OF THE MOST X-RAY LUMINOUS RADIO-QUIET ROSAT BRIGHT SURVEY-QSOs: A REFERENCE SAMPLE FOR THE INTERPRETATION OF HIGH-REDSHIFT QSO SPECTRA

    International Nuclear Information System (INIS)

    We present the broadband X-ray properties of four of the most X-ray luminous (LX ≥ 1045 erg s-1 in the 0.5-2 keV band) radio-quiet QSOs found in the ROSAT Bright Survey. This uniform sample class, which explores the extreme end of the QSO luminosity function, exhibits surprisingly homogenous X-ray spectral properties: a soft excess with an extremely smooth shape containing no obvious discrete features, a hard power law above 2 keV, and a weak narrow/barely resolved Fe Kα fluorescence line for the three high signal-to-noise ratio (S/N) spectra. The soft excess can be well fitted with only a soft power law. No signatures of warm or cold intrinsic absorbers are found. The Fe Kα centroids and the line widths indicate emission from neutral Fe (E = 6.4 keV) originating from cold material from distances of only a few light days or further out. The well-constrained equivalent widths (EW) of the neutral Fe lines are higher than expected from the X-ray Baldwin effect which has been only poorly constrained at very high luminosities. Taking into account our individual EW measurements, we show that the X-ray Baldwin effect flattens above LX ∼ 1044 erg s-1 (2-10 keV band) where an almost constant (EW) of ∼100 eV is found. We confirm the assumption of having very similar X-ray active galactic nucleus properties when interpreting stacked X-ray spectra. Our stacked spectrum serves as a superb reference for the interpretation of low S/N spectra of radio-quiet QSOs with similar luminosities at higher redshifts routinely detected by XMM-Newton and Chandra surveys.

  4. NuSTAR study of hard X-ray morphology and spectroscopy of PWN G21.5-0.9

    DEFF Research Database (Denmark)

    Nynka, Melania; Hailey, Charles J.; Reynolds, Stephen P.;

    2014-01-01

    and Eastern Limb results predominantly from non-thermal processes. We detect a break in the spatially integrated X-ray spectrum at similar to 9 keV that cannot be reproduced by current spectral energy distribution models, implying either a more complex electron injection spectrum or an additional process......STAR agrees well with that seen by XMM-Newton and Chandra below 10 keV. At high energies, NuSTAR clearly detects non-thermal emission up to similar to 20 keV that extends along the eastern and northern rim of the supernova shell. The broadband images clearly demonstrate that X-ray emission from the North Spur...

  5. G359.97-0.038: A Hard X-Ray Filament Associated with a Supernova Shell-Molecular Cloud Interaction

    DEFF Research Database (Denmark)

    Nynka, Melania; Hailey, Charles J.; Zhang, Shuo;

    2015-01-01

    near Sgr A*. Its NuSTAR and Chandra broadband spectrum is characterized by a single power law with Γ = 1.3 ± 0.3 that extends from 2 to 50 keV, with an unabsorbed luminosity of 1.3 × 1033 erg s-1 (d/8 kpc)2 in the 2-8 keV band. Despite possessing a cometary X-ray morphology that is typical of a pulsar...

  6. X-rays spectrum and air Kerma during a mammography study; Espectro de los rayos X y Kerma en aire durante un estudio mamografico

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez G, J. [Instituto Nacional de Estadistica Geografia e Informatica, Av. Heroes de Nacozari Sur 2301, Fracc. Jardines del Parque, 20276 Aguascalientes (Mexico); Hernandez V, R.; Hernandez D, V. M.; Vega C, H. R. [Unidad Academica de Estudios Nucleares, Universidad Autonoma de Zacatecas, Cipres 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)], e-mail: fermineutron@yahoo.com

    2009-10-15

    In this calculation series was modeled the source of electrons, the target and the filter. Using thermoluminescent dosemeters of ZrO{sub 2}+PTFE the air Kerma was measured in five points located on a phantom made with acrylic and water when it was exposed to a X-rays beam produced by electrons of 24 KeV and 10 m A of current that produces a mammography. The air Kerma values at the entrance surface of the phantom were compared with values calculated by Monte Carlo methods. The air Kerma values measured indicate that approximately the five points receive the same air Kerma, what means that the beam is homogeneous, of the Monte Carlo calculations we find that the center receives a greater dose what implies that the beam is not uniform, the explanation of this fact is attributed to was used a simple model in the calculations, nevertheless, the air Kerma average measured at the entrance surface of the phantom was of 0.96 +{sub -} 0.03 m G, while the other obtained by the calculations was of 0.96 +{sub -} 0.06 mGy, to compare both do not exist significant differences. (author)

  7. X-ray photoelectron spectrum and electronic properties of a noncentrosymmetric chalcopyrite compound HgGa(2)S(4): LDA, GGA, and EV-GGA.

    Science.gov (United States)

    Reshak, Ali Hussain; Khenata, R; Kityk, I V; Plucinski, K J; Auluck, S

    2009-04-30

    An all electron full potential linearized augmented plane wave method has been applied for a theoretical study of the band structure, density of states, and electron charge density of a noncentrosymmetric chalcopyrite compound HgGa(2)S(4) using three different approximations for the exchange correlation potential. Our calculations show that the valence band maximum (VBM) and conduction band minimum (CBM) are located at Gamma resulting in a direct energy gap of about 2.0, 2.2, and 2.8 eV for local density approximation (LDA), generalized gradient approximation (GGA), and Engel-Vosko (EVGGA) compared to the experimental value of 2.84 eV. We notice that EVGGA shows excellent agreement with the experimental data. This agreement is attributed to the fact that the Engel-Vosko GGA formalism optimizes the corresponding potential for band structure calculations. We make a detailed comparison of the density of states deduced from the X-ray photoelectron spectra with our calculations. We find that there is a strong covalent bond between the Hg and S atoms and Ga and S atoms. The Hg-Hg, Ga-Ga, and S-S bonds are found to be weaker than the Hg-S and Ga-S bonds showing that a covalent bond exists between Hg and S atoms and Ga and S atoms.

  8. Observing broad-absorption line quasars with Spectrum-Rontgen-Gamma

    DEFF Research Database (Denmark)

    Singh, K.P.; Schnopper, H.W.; Westergaard, Niels Jørgen Stenfeldt

    1998-01-01

    Broad-absorption line quasars are found to have extremely weak soft X-ray emission when compared with other optically selected quasars. In the only example of PHL 5200 for which a detailed X-ray spectrum has been obtained with ASCA, strong absorption in the source appears to be responsible for the...... lack of soft Xray emission. Broad-band X-ray observations of a sample of BAL QSOs are proposed with a high throughput mission SPECTRUM-RONTGEN-GAMMA (SRG), to find out whether these sources are intrinsically weak over the entire bandwidth of X-rays or only in the soft X-rays due to absorption resulting...... from the line of sight passing through large column density clouds. Simultaneous UV observations will help to constrain the ionization state of the absorbers, and also improve the overall UV to X-ray continuum measurements in them....

  9. 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…

  10. 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.

  11. X-ray lithography sources

    International Nuclear Information System (INIS)

    Synchrotron from dipole magnets in electron storage rings has emerged as a useful source of x-rays for lithography. To meet the need for these sources numerous groups around the world have embarked on projects to design and construct storage rings for x-ray lithography. Both conventional electromagnets as well as superconducting (SC) dipoles have been incorporated into the various designs. An overview of the worldwide effort to produce commercial x-ray sources will be presented. To better illustrate the elements involved in these sources a closer examination of the Superconducting X-ray Lithography Source Project (SXLS) at BNL will be presented. 11 refs., 1 fig., 5 tabs

  12. 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.

  13. 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.

  14. 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...

  15. X-Ray Emission from the Soft X-Ray Transient Aquila X-1

    Science.gov (United States)

    Tavani, Marco

    1998-01-01

    Aquila X-1 is the most prolific of soft X-ray transients. It is believed to contain a rapidly spinning neutron star sporadically accreting near the Eddington limit from a low-mass companion star. The interest in studying the repeated X-ray outbursts from Aquila X-1 is twofold: (1) studying the relation between optical, soft and hard X-ray emission during the outburst onset, development and decay; (2) relating the spectral component to thermal and non-thermal processes occurring near the magnetosphere and in the boundary layer of a time-variable accretion disk. Our investigation is based on the BATSE monitoring of Aquila X-1 performed by our group. We observed Aquila X-1 in 1997 and re-analyzed archival information obtained in April 1994 during a period of extraordinary outbursting activity of the source in the hard X-ray range. Our results allow, for the first time for this important source, to obtain simultaneous spectral information from 2 keV to 200 keV. A black body (T = 0.8 keV) plus a broken power-law spectrum describe accurately the 1994 spectrum. Substantial hard X-ray emission is evident in the data, confirming that the accretion phase during sub-Eddington limit episodes is capable of producing energetic hard emission near 5 x 10(exp 35) ergs(exp -1). A preliminary paper summarizes our results, and a more comprehensive account is being written. We performed a theoretical analysis of possible emission mechanisms, and confirmed that a non-thermal emission mechanism triggered in a highly sheared magnetosphere at the accretion disk inner boundary can explain the hard X-ray emission. An anticorrelation between soft and hard X-ray emission is indeed prominently observed as predicted by this model.

  16. Gamma detector for use with luggage X-ray systems

    International Nuclear Information System (INIS)

    A new gamma radiation sensor has been designed for installation on several types of luggage x-ray machines and mobile x-ray vans operated by the U.S. Customs Service and the U.S. Department of State. The use of gamma detectors on x-ray machines imposed difficulties not usually encountered in the design of gamma detectors because the spectrum of scattered x-rays, which varied from machine to machine, extended to energies significantly higher than those of the low-energy isotopic emissions. In the original design, the lower level discriminator was raised above the x-ray end point energy resulting in the loss of the americium line associated with plutonium. This reduced the overall sensitivity to unshielded plutonium by a factor of approximately 100. An improved method was subsequently developed wherein collimation was utilized in conjunction with a variable counting threshold to permit accommodation of differing conditions of x-ray scattering. This design has been shown to eliminate most of the problems due to x-ray scattering while still capturing the americium emissions. The overall sensitivity has remained quite high, though varying slightly from one model of x-ray machine to another, depending upon the x-ray scattering characteristics of each model. (author)

  17. Soft X-ray astronomy using grazing incidence optics

    International Nuclear Information System (INIS)

    The instrumental background of X-ray astronomy with an emphasis on high resolution imagery is outlined. Optical and system performance, in terms of resolution, are compared and methods for improving the latter in finite length instruments described. The method of analysis of broadband images to obtain diagnostic information is described and is applied to the analysis of coronal structures

  18. Visible-frequency metasurfaces for broadband anomalous reflection and high-efficiency spectrum splitting.

    Science.gov (United States)

    Li, Zhongyang; Palacios, Edgar; Butun, Serkan; Aydin, Koray

    2015-03-11

    Ultrathin metasurfaces have recently emerged as promising materials that have huge potential to enable novel, flat optical components, and surface-confined, miniature photonic devices. Metasurfaces offer new degrees of freedom in molding the optical wavefronts by introducing abrupt and drastic changes in the amplitude, phase, and/or polarization of electromagnetic radiation at the wavelength scale. By carefully arranging multiple subwavelength anisotropic or gradient optical resonators, metasurfaces have been shown to enable anomalous transmission, anomalous reflection, optical holograms, and spin-orbit interaction. However, experimental realization of high-performance metasurfaces that can operate at visible frequency range has been a significant challenge due to high optical losses of plasmonic materials and difficulties in fabricating several plasmonic resonators of subwavelength size with high uniformity. Here, we propose a highly efficient yet a simple metasurface design comprising of a single, anisotropic silver antenna in its unit cell. We demonstrate broadband (450-850 nm) anomalous reflection and spectrum splitting at visible and near-IR frequencies with high conversion efficiency. Average power ratio of anomalous reflection to the strongest diffraction mode was calculated to be on the order of 10(3) and measured to be on the order of 10. The anomalous reflected photons have been visualized using a charge-coupled device camera, and broadband spectrum splitting performance has been confirmed experimentally using a free space, angle-resolved reflection measurement setup. Metasurface design proposed in this study is a clear departure from conventional metasurfaces utilizing multiple, anisotropic and/or gradient optical resonators and could enable high-efficiency, broadband metasurfaces for achieving flat high signal-to-noise ratio optical spectrometers, polarization beam splitters, directional emitters, and spectrum splitting surfaces for photovoltaics. PMID

  19. NuSTAR study of Hard X-Ray Morphology and Spectroscopy of PWN G21.5-0.9

    CERN Document Server

    Nynka, Melania; Reynolds, Stephen P; An, Hongjun; Baganoff, Frederick K; Boggs, Steven E; Christensen, Finn E; Craig, William W; Gotthelf, Eric V; Grefenstette, Brian W; Harrison, Fiona A; Krivonos, Roman; Madsen, Kristin K; Mori, Kaya; Perez, Kerstin; Stern, Daniel; Wik, Daniel R; Zhang, William W; Zoglauer, Andreas

    2014-01-01

    We present NuSTAR high energy X-ray observations of the pulsar wind nebula (PWN)/supernova remnant G21.5-0.9. We detect integrated emission from the nebula up to ~40 keV, and resolve individual spatial features over a broad X-ray band for the first time. The morphology seen by NuSTAR agrees well with that seen by XMM-Newton and Chandra below 10 keV. At high energies NuSTAR clearly detects non-thermal emission up to ~20 keV that extends along the eastern and northern rim of the supernova shell. The broadband images clearly demonstrate that X-ray emission from the North Spur and Eastern Limb results predominantly from non-thermal processes. We detect a break in the spatially integrated X-ray spectrum at ~9 keV that cannot be reproduced by current SED models, implying either a more complex electron injection spectrum or an additional process such as diffusion compared to what has been considered in previous work. We use spatially resolved maps to derive an energy-dependent cooling length scale, $L(E) \\propto E^{...

  20. Spectral and timing properties of the accreting X-ray millisecond pulsar IGR J17498-2921

    CERN Document Server

    Falanga, M; Poutanen, J; Galloway, D K; Bozzo, E; Goldwurm, A; Hermsen, W; Stella, L

    2012-01-01

    We analyze the spectral and timing properties of IGR J17498-2921 and the characteristics of X-ray bursts to constrain the physical processes responsible for the X-ray production in this class of sources. The broad-band average spectrum is well-described by thermal Comptonization with an electron temperature of kT_e ~ 50 keV, soft seed photons of kT_bb ~ 1 keV, and Thomson optical depth \\taut ~ 1 in a slab geometry. The slab area corresponds to a black body radius of R_bb ~9 km. During the outburst, the spectrum stays remarkably stable with plasma and soft seed photon temperatures and scattering optical depth that are constant within the errors. This behavior has been interpreted as indicating that the X-ray emission originates above the neutron star (NS) surface in a hot slab (either the heated NS surface or the accretion shock). The INTEGRAL, RXTE, and Swift data reveal the X-ray pulsation at a period of 2.5 milliseconds up to ~65 keV. The pulsed fraction is consistent with being constant, i.e. energy indepe...

  1. Radioisotope x-ray analysis

    International Nuclear Information System (INIS)

    Radioisotope x-ray fluorescence and x-ray preferential absorption (XRA) techniques are used extensively for the analysis of materials, covering such diverse applications as analysis of alloys, coal, environmental samples, paper, waste materials, and metalliferous mineral ores and products. Many of these analyses are undertaken in the harsh environment of industrial plants and in the field. Some are continuous on-line analyses of material being processed in industry, where instantaneous analysis information is required for the control of rapidly changing processes. Radioisotope x-ray analysis systems are often tailored to a specific but limited range of applications. They are simpler and often considerably less expensive than analysis systems based on x-ray tubes. These systems are preferred to x-ray tube techniques when simplicity, ruggedness, reliability, and cost of equipment are important; when minimum size, weight, and power consumption are necessary; when a very constant and predictable x-ray output is required; when the use of high-energy x-rays is advantageous; and when short x-ray path lengths are required to minimize the absorption of low-energy x-rays in air. This chapter reviews radioisotope XRF, preferential absorption, and scattering techniques. Some of the basic analysis equations are given. The characteristics of radioisotope sources and x-ray detectors are described, and then the x-ray analytical techniques are presented. The choice of radioisotope technique for a specific application is discussed. This is followed by a summary of applications of these techniques, with a more detailed account given of some of the applications, particularly those of considerable industrial importance. 79 refs., 28 figs., 7 tabs

  2. Investigation of stability and x-ray spectrum in gas-puff z-pinch plasmas diriven by inductive energy storage pulsed power generator with a plasma opening switch

    Energy Technology Data Exchange (ETDEWEB)

    Murayama, K.; Fukudome, I. [Yatsushiro National College of Technology, Dept. of Mechanical and Electrical Engineering, Yatsushiro, Kumamoto (Japan); Teramoto, Y.; Katsuki, S.; Akiyama, H. [Kumamoto Univ., Dept. of Electrical and Computer Engineering, Kumamoto (Japan)

    2002-06-01

    Gas-puff z-pinch plasmas are driven by an inductive voltage adder - inductive energy storage pulsed power generator ''ASO-X''. ASO-X has the performance of the maximum output voltage and current are 180 kV and 400 kA respectively and can provide a fast rise time current with operating POS. The stability of the plasma column, spectrum radiated from z-pinch plasmas and the spatial distribution of hot spots are investigated in the case with and without operating POS. By driving ASO-X with operating POS the kink instability is restrained and the stability of plasma column is improved about three times in regard to the average dispersion. Furthermore the duration of soft x-ray radiation is increased and the spatial distribution of hot spots is 50% improved with regard to kurtosis of the intensity profile of pinhole photographs compared to those without operating POS. (author)

  3. Chandra reveals a black-hole X-ray binary within the ultraluminous supernova remnant MF 16

    OpenAIRE

    Roberts, T P; Colbert, E. J. M.

    2003-01-01

    We present evidence, based on Chandra ACIS-S observations of the nearby spiral galaxy NGC 6946, that the extraodinary X-ray luminosity of the MF 16 supernova remnant actually arises in a black-hole X-ray binary. This conclusion is drawn from the point-like nature of the X-ray source, its X-ray spectrum closely resembling the spectrum of other ultraluminous X-ray sources thought to be black-hole X-ray binary systems, and the detection of rapid hard X-ray variability from the source. We briefly...

  4. Portable energy dispersive X-ray fluorescence and X-ray diffraction and radiography system for archaeometry

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza Cuevas, Ariadna, E-mail: ariadna@mail.or [Archaeometry Laboratory, Colegio Universitario San Geronimo de La Habana, Obispo, entre San Ignacio y Mercaderes, Habana Vieja, cp 10 100, Havana (Cuba); Perez Gravie, Homero, E-mail: homero.perezgravie@mail.co [Archaeometry Laboratory, Colegio Universitario San Geronimo de La Habana, Obispo, entre San Ignacio y Mercaderes, Habana Vieja, cp 10 100, Havana (Cuba)

    2011-03-21

    Starting on a laboratory developed portable X-ray fluorescence (PXRF) spectrometer; three different analytical results can be performed: analysis of chemical elements, analysis of major chemical crystalline phase and structural analysis, which represents a contribution to a new, low cost development of portable X-ray analyzer; since these results are respectively obtained with independent equipments for X-ray fluorescence, X-ray diffraction and radiography. Detection limits of PXRF were characterized using standard reference materials for ceramics, glass, bronze and bones, which are the main materials requiring quantitative analysis in art and archeological objects. A setup for simultaneous energy dispersive X-ray fluorescence and diffraction (ED (XRF-XRD)) in the reflection mode has been tested for in situ and non-destructive analysis according to the requirements of art objects inspection. The system uses a single low power X-ray tube and an X-ray energy dispersive detector to measure X-ray diffraction spectrum at a fixed angle. Application to the identification of jadeite-jade mineral in archeological objects by XRD is presented. A local high resolution radiography image obtained with the same low power X-ray tube allows for studies in painting and archeological bones.

  5. Blazar microvariability at hard X-rays

    OpenAIRE

    Foschini, L.; Gliozzi, M.; Pian, E.; Tagliaferri, G.; Tavecchio, F.; Bianchin, V.; L. Maraschi(INAF National Institute for Astrophysics, I-00136 Rome, Italy); Sambruna, R. M.; Di Cocco, G.; Ghisellini, G.; Malaguti, G.; Tosti, G.; Treves, A.

    2007-01-01

    Blazars are known to display strong and erratic variability at almost all the wavelengths of electromagnetic spectrum. Presently, variability studies at high-energies (hard X-rays, gamma-rays) are hampered by low sensitivity of the instruments. Nevertheless, the latest generation of satellites (INTEGRAL, Swift) have given suggestions not yet fully confirmed of variability on intraday timescales. Some specific cases recently observed are presented and physical implications are discussed (e.g. ...

  6. Powerful jets from black hole X-ray binaries in Low/Hard X-ray states

    OpenAIRE

    Fender, R. P.

    2000-01-01

    Four persistent (Cygnus X-1, GX 339-4, GRS 1758-258 and 1E 1740.7-2942) and three transient (GS 2023+38, GRO J0422+32 and GS 1354-64) black hole X-ray binary systems have been extensively observed at radio wavelengths during extended periods in the Low/Hard X-ray state, which is characterised in X-rays by a hard power-law spectrum and strong variability. All seven systems show a persistent flat or inverted (in the sense that spectral index alpha >= 0) radio spectrum in this state, markedly di...

  7. ON THE CLUSTER PHYSICS OF SUNYAEV-ZEL'DOVICH AND X-RAY SURVEYS. II. DECONSTRUCTING THE THERMAL SZ POWER SPECTRUM

    Energy Technology Data Exchange (ETDEWEB)

    Battaglia, N. [Department of Astronomy and Astrophysics, University of Toronto, 50 St George, Toronto, ON M5S 3H4 (Canada); Bond, J. R.; Pfrommer, C.; Sievers, J. L. [Canadian Institute for Theoretical Astrophysics, 60 St George, Toronto, ON M5S 3H8 (Canada)

    2012-10-20

    Secondary anisotropies in the cosmic microwave background are a treasure-trove of cosmological information. Interpreting current experiments probing them are limited by theoretical uncertainties rather than by measurement errors. Here we focus on the secondary anisotropies resulting from the thermal Sunyaev-Zel'dovich (tSZ) effect; the amplitude of which depends critically on the average thermal pressure profile of galaxy groups and clusters. To this end, we use a suite of hydrodynamical TreePM-SPH simulations that include radiative cooling, star formation, supernova feedback, and energetic feedback from active galactic nuclei. We examine in detail how the pressure profile depends on cluster radius, mass, and redshift and provide an empirical fitting function. We employ three different approaches for calculating the tSZ power spectrum: an analytical approach that uses our pressure profile fit, a semianalytical method of pasting our pressure fit onto simulated clusters, and a direct numerical integration of our simulated volumes. We demonstrate that the detailed structure of the intracluster medium and cosmic web affect the tSZ power spectrum. In particular, the substructure and asphericity of clusters increase the tSZ power spectrum by 10%-20% at l {approx} 2000-8000, with most of the additional power being contributed by substructures. The contributions to the power spectrum from radii larger than R {sub 500} is {approx}20% at l = 3000, thus clusters interiors (r < R {sub 500}) dominate the power spectrum amplitude at these angular scales.

  8. 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 ...

  9. X-ray diagnostic equipment

    International Nuclear Information System (INIS)

    An X-ray tube is connected to several different image processing devices in X-ray diagnostic equipment. Only a single organ selector is allocated to it, for which the picture parameters for each image processing device are selected. The choice of the correct combination of picture parameters is made by means of a selector switch. (DG)

  10. X-ray tube arrangement

    International Nuclear Information System (INIS)

    An x-ray tube is described incorporating an elongated target/ anode over which the electron beam is deflected and from which x-rays are emitted. Improved methods of monitoring and controlling the amplitude of the beam deflection are presented. (U.K.)

  11. New Observations of Soft X-ray (0.5-5 keV) Solar Spectra

    Science.gov (United States)

    Caspi, A.; Woods, T. N.; Mason, J. P.; Jones, A. R.; Warren, H. P.

    2013-12-01

    The solar corona is the brightest source of X-rays in the solar system, and the X-ray emission is highly variable on many time scales. However, the actual solar soft X-ray (SXR) (0.5-5 keV) spectrum is not well known, particularly during solar quiet periods, as, with few exceptions, this energy range has not been systematically studied in many years. Previous observations include high-resolution but very narrow-band spectra from crystal spectrometers (e.g., Yohkoh/BCS), or integrated broadband irradiances from photometers (e.g., GOES/XRS, TIMED/XPS, etc.) that lack detailed spectral information. In recent years, broadband measurements with moderate energy resolution (~0.5-0.7 keV FWHM) were made by SphinX on CORONAS-Photon and SAX on MESSENGER, although they did not extend to energies below ~1 keV. We present observations of solar SXR emission obtained using new instrumentation flown on recent SDO/EVE calibration rocket underflights. The photon-counting spectrometer, a commercial Amptek X123 with a silicon drift detector and an 8 μm Be window, measures the solar disk-integrated SXR emission from ~0.5 to >10 keV with ~0.15 keV FWHM resolution and 1 s cadence. A novel imager, a pinhole X-ray camera using a cooled frame-transfer CCD (15 μm pixel pitch), Ti/Al/C filter, and 5000 line/mm Au transmission grating, images the full Sun in multiple spectral orders from ~0.1 to ~5 nm with ~10 arcsec/pixel and ~0.01 nm/pixel spatial and spectral detector scales, respectively, and 10 s cadence. These instruments are prototypes for future CubeSat missions currently being developed. We present new results of solar observations on 04 October 2013 (NASA sounding rocket 36.290). We compare with previous results from 23 June 2012 (NASA sounding rocket 36.286), during which solar activity was low and no signal was observed above ~4 keV. We compare our spectral and imaging measurements with spectra and broadband irradiances from other instruments, including SDO/EVE, GOES/XRS, TIMED

  12. Nature of Hard X-ray Source from Optical Identification of the ASCA Large Sky Survey

    OpenAIRE

    Akiyama, M.; Ohta, K.; Yamada, T.; Ueda, Y.; Takahashi, T.; M. SAKANO; Tsuru, T.; Lehmann, I.; G. Hasinger(JHU)

    1998-01-01

    We present results of optical identification of the ASCA Large Sky Survey. X-ray sources which have hard X-ray spectra were identified with type-2 AGN at redshifts smaller than 0.5. It is supported that the absorbed X-ray spectrum of type-2 AGN makes the Cosmic X-ray Background harder in the hard X-ray band than type-1 AGN, which is main contributer in the soft X-ray band. Absence of type-2 AGN at redshift larger than 1 in the identified sample, which contrasts to the existence of 6 broad-lin...

  13. Suzaku view of the Be/X-ray binary pulsar GX 304-1 during Type I X-ray outbursts

    Science.gov (United States)

    Jaisawal, Gaurava K.; Naik, Sachindra; Epili, Prahlad

    2016-04-01

    We report the timing and spectral properties of the Be/X-ray binary pulsar GX 304-1 using two Suzaku observations during its 2010 August and 2012 January X-ray outbursts. Pulsations at ˜275 s were clearly detected in the light curves from both observations. Pulse profiles were found to be strongly energy-dependent. During the 2010 observation, the prominent dips seen in soft X-ray (≤10 keV) pulse profiles were found to be absent at higher energies. However, during the 2012 observation, the pulse profiles were complex as a result of the presence of several dips. Significant changes in the shape of the pulse profiles were detected at high energies (>35 keV). A phase shift of ˜0.3 was detected while comparing the phase of the main dip in the pulse profiles below and above ˜35 keV. The broad-band energy spectrum of the pulsar was well described by a partially absorbed negative and positive power law with exponential cut-off (NPEX) model with 6.4-keV iron line and a cyclotron absorption feature. The energy of the cyclotron absorption line was found to be ˜53 and 50 keV for the 2010 and 2012 observations, respectively, indicating a marginal positive dependence on source luminosity. Based on the results obtained from phase-resolved spectroscopy, the absorption dips in the pulse profiles can be interpreted as due to the presence of additional matter at same phases. Observed positive correlation between the cyclotron line energy and luminosity, and the significant pulse-phase variation of cyclotron parameters are discussed from the perspective of theoretical models on the cyclotron absorption line in X-ray pulsars.

  14. High Spectral Resolution, High Cadence, Imaging X-ray Microcalorimeters for Solar Physics - Phase 2 Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Microcalorimeter x-ray instruments are non-dispersive, high spectral resolution, broad-band, high cadence imaging spectrometers. We have been developing these...

  15. Incoherent x-ray scattering in single molecule imaging

    CERN Document Server

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

    2014-01-01

    Imaging of the structure of single proteins or other biomolecules with atomic resolution would be enormously beneficial to structural biology. X-ray free-electron lasers generate highly intense and ultrashort x-ray pulses, providing a route towards imaging of single molecules with atomic resolution. The information on molecular structure is encoded in the coherent x-ray scattering signal. In contrast to crystallography there are no Bragg reflections in single molecule imaging, which means the coherent scattering is not enhanced. Consequently, a background signal from incoherent scattering deteriorates the quality of the coherent scattering signal. This background signal cannot be easily eliminated because the spectrum of incoherently scattered photons cannot be resolved by usual scattering detectors. We present an ab initio study of incoherent x-ray scattering from individual carbon atoms, including the electronic radiation damage caused by a highly intense x-ray pulse. We find that the coherent scattering pa...

  16. X-Ray Absorption and Scattering by Interstellar Grains

    CERN Document Server

    Hoffman, John A

    2015-01-01

    Interstellar abundance determinations from fits to X-ray absorption edges often rely on the following false assumptions: (1) the grains are "optically thin" at the observed X-ray wavelengths, and (2) scattering is insignificant and can be ignored. We show instead that scattering contributes significantly to the attenuation of X-rays for realistic dust grain size distributions and substantially modifies the spectrum near absorption edges of elements present in grains. The dust attenuation modules used in major X-ray spectral fitting programs do not take this into account. We show that the consequences of neglecting scattering on the determination of interstellar elemental abundances are modest; however, scattering (along with uncertainties in the grain size distribution) must be taken into account when near-edge extinction fine structure is used to infer dust mineralogy. We advertise the benefits and accuracy of anomalous diffraction theory for both X-ray halo analysis and near edge absorption studies. An open...

  17. Models for x-ray emission from Tycho's remnant

    International Nuclear Information System (INIS)

    The authors reexamine the x-ray emission from Tycho's remnant using results from hydrodynamic models computed with a detailed spherically symmetric code. The observed synchrotron radio contours appear to require a cloudy circumstellar medium. The authors explore the x-ray emission properties of similar models. They find that they tend to produce broad shells of x-ray emission that resemble the observed x-ray observations, but it has little similarity to the evolution of remnants in cloudy media dominated by thermal conduction. More work needs to be done to ensure that the spectrum as well as the x-ray map can be modeled with the same cloudy circumstellar medium, although we believe it will not be difficult to obtain as good as statistical agreement with the spectral data as other models have achieved

  18. Soft X-ray irradiation of methanol ice: Formation of products as a function of photon energy

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y.-J.; Juang, K.-J.; Yih, T.-S. [Department of Physics, National Central University, Jhongli City, Taoyuan County 32054, Taiwan (China); Ciaravella, A.; Cecchi-Pestellini, C. [INAF-Osservatorio Astronomico di Palermo, P.za Parlamento 1, I-90134 Palermo (Italy); Muñoz Caro, G. M.; Jiménez-Escobar, A., E-mail: aciaravella@astropa.unipa.it [Centro de Astrobiología (INTA-CSIC), Carretera de Ajalvir, km 4, Torrejón de Ardoz, E-28850 Madrid (Spain)

    2013-12-01

    Pure methanol ices have been irradiated with monochromatic soft X-rays of 300 and 550 eV close to the 1s resonance edges of C and O, respectively, and with a broadband spectrum (250-1200 eV). The infrared (IR) spectra of the irradiated ices show several new products of astrophysical interest such as CH{sub 2}OH, H{sub 2}CO, CH{sub 4}, HCOOH, HCOCH{sub 2}OH, CH{sub 3}COOH, CH{sub 3}OCH{sub 3}, HCOOCH{sub 3}, and (CH{sub 2}OH){sub 2}, as well as HCO, CO, and CO{sub 2}. The effect of X-rays is the result of the combined interactions of photons and electrons with the ice. A significant contribution to the formation and growth of new species in the CH{sub 3}OH ice irradiated with X-rays is given by secondary electrons, whose energy distribution depends on the energy of X-ray photons. Within a single experiment, the abundances of the new products increase with the absorbed energy. Monochromatic experiments show that product abundances also increase with the photon energy. However, the abundances per unit energy of newly formed species show a marked decrease in the broadband experiment as compared to irradiations with monochromatic photons, suggesting a possible regulatory role of the energy deposition rate. The number of new molecules produced per absorbed eV in the X-ray experiments has been compared to those obtained with electron and ultraviolet (UV) irradiation experiments.

  19. Asian conference on x-rays and related techniques in research and industry. Proceedings

    International Nuclear Information System (INIS)

    This proceedings compile the paper presented at the conference. The papers for presentation are from wide spectrum stressing the interdisciplinary nature of the conference i.e. x-ray fluorescence spectrometry (XRF), x-ray diffraction (XRD), TEM, scanning electron microscope (SEM), energy dispersive x-ray (EDX), auger electron microscopy, electron back scatter diffraction (EBSD)

  20. High flux coherent supercontinuum soft X-ray source driven by a single-stage 10 mJ, kHz, Ti:sapphire laser amplifier

    CERN Document Server

    Ding, Chengyuan; Fan, Tingting; Hickstein, Daniel D; Popmintchev, Tenio; Zhang, Xiaoshi; Walls, Mike; Murnane, Margaret M; Kapteyn, Henry C

    2014-01-01

    We demonstrate the highest flux tabletop source of coherent soft X-rays to date, driven by a single-stage 10 mJ Ti:sapphire regenerative amplifier at 1 kHz. We first down-convert the laser to 1.3 um using a parametric amplifier, before up-converting it to soft X-rays using high harmonic generation in a high-pressure, phase matched, hollow waveguide geometry. The resulting optimally phase matched broadband spectrum extends to 200 eV, with a soft X-ray photon flux of > 10^6 photons/pulse/1% bandwidth at 1 kHz, corresponding to > 10^9 photons/s/1% bandwidth, or approximately a three order-of-magnitude increase compared with past work. Finally, using this broad bandwidth X-ray source, we demonstrate X-ray absorption spectroscopy of multiple elements and transitions in molecules in a single spectrum, with a spectral resolution of 0.25 eV, and with the ability to resolve the near edge fine structure.

  1. Bright circularly polarized soft X-ray high harmonics for X-ray magnetic circular dichroism.

    Science.gov (United States)

    Fan, Tingting; Grychtol, Patrik; Knut, Ronny; Hernández-García, Carlos; Hickstein, Daniel D; Zusin, Dmitriy; Gentry, Christian; Dollar, Franklin J; Mancuso, Christopher A; Hogle, Craig W; Kfir, Ofer; Legut, Dominik; Carva, Karel; Ellis, Jennifer L; Dorney, Kevin M; Chen, Cong; Shpyrko, Oleg G; Fullerton, Eric E; Cohen, Oren; Oppeneer, Peter M; Milošević, Dejan B; Becker, Andreas; Jaroń-Becker, Agnieszka A; Popmintchev, Tenio; Murnane, Margaret M; Kapteyn, Henry C

    2015-11-17

    We demonstrate, to our knowledge, the first bright circularly polarized high-harmonic beams in the soft X-ray region of the electromagnetic spectrum, and use them to implement X-ray magnetic circular dichroism measurements in a tabletop-scale setup. Using counterrotating circularly polarized laser fields at 1.3 and 0.79 µm, we generate circularly polarized harmonics with photon energies exceeding 160 eV. The harmonic spectra emerge as a sequence of closely spaced pairs of left and right circularly polarized peaks, with energies determined by conservation of energy and spin angular momentum. We explain the single-atom and macroscopic physics by identifying the dominant electron quantum trajectories and optimal phase-matching conditions. The first advanced phase-matched propagation simulations for circularly polarized harmonics reveal the influence of the finite phase-matching temporal window on the spectrum, as well as the unique polarization-shaped attosecond pulse train. Finally, we use, to our knowledge, the first tabletop X-ray magnetic circular dichroism measurements at the N4,5 absorption edges of Gd to validate the high degree of circularity, brightness, and stability of this light source. These results demonstrate the feasibility of manipulating the polarization, spectrum, and temporal shape of high harmonics in the soft X-ray region by manipulating the driving laser waveform.

  2. The Variable Hard X-Ray Emission of NGC4945 as Observed by NuSTAR

    Science.gov (United States)

    Puccetti, Simonetta; Comastri, Andrea; Fiore, Fabrizio; Arevalo, Patricia; Risaliti, Guido; Bauer, Franz E.; Brandt, William N.; Stern, Daniel; Harrison, Fiona A.; Alexander, David M.; Boggs, Steve E.; Christensen, Finn E.; Craig, William W.; Gandhi, Poshak; Hailey, Charles J.; Koss, Michael R.; Lansbury, George B.; Luo, Bin; Madejski, Greg M.; Matt, Giorgio; Walton, Dominic J.; Zhang, Will

    2014-01-01

    We present a broadband (approx. 0.5 - 79 keV) spectral and temporal analysis of multiple NuSTAR observations combined with archival Suzaku and Chandra data of NGC4945, the brightest extragalactic source at 100 keV. We observe hard X-ray (> 10 keV) flux and spectral variability, with flux variations of a factor 2 on timescales of 20 ksec. A variable primary continuum dominates the high energy spectrum (> 10 keV) in all the states, while the reflected/scattered flux which dominates at E< 10 keV stays approximately constant. From modelling the complex reflection/transmission spectrum we derive a Compton depth along the line of sight of Thomson approx.2.9, and a global covering factor for the circumnuclear gas of approx. 0.15. This agrees with the constraints derived from the high energy variability, which implies that most of the high energy flux is transmitted, rather that Compton-scattered. This demonstrates the effectiveness of spectral analysis in constraining the geometric properties of the circumnuclear gas, and validates similar methods used for analyzing the spectra of other bright, Compton-thick AGN. The lower limits on the e-folding energy are between 200 - 300 keV, consistent with previous BeppoSAX, Suzaku and Swift BAT observations. The accretion rate, estimated from the X-ray luminosity and assuming a bolometric correction typical of type 2 AGN, is in the range approx. 0.1 - 0.3 lambda(sub Edd) depending on the flux state. The substantial observed X-ray luminosity variability of NGC4945 implies that large errors can arise from using single-epoch X-ray data to derive L/L(sub Edd) values for obscured AGNs.

  3. The variable hard X-ray emission of NGC 4945 as observed by NuSTAR

    Energy Technology Data Exchange (ETDEWEB)

    Puccetti, Simonetta [ASDC-ASI, Via del Politecnico, I-00133 Roma (Italy); Comastri, Andrea [INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna (Italy); Fiore, Fabrizio [INAF-Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monte Porzio Catone (RM) (Italy); Arévalo, Patricia; Bauer, Franz E. [Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, 306, Santiago 22 (Chile); Risaliti, Guido [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy); Brandt, William N.; Luo, Bin [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Harrison, Fiona A. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Alexander, David M.; Gandhi, Poshak; Lansbury, George B. [Department of Physics, Durham University, Durham DH1 3LE (United Kingdom); Boggs, Steve 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, 2800 Lyngby (Denmark); Hailey, Charles J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Koss, Michael J. [Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland); Madejski, Greg M. [Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Matt, Giorgio [Dipartimento di Matematica e Fisica, Universit' a Roma Tre, via della Vasca Navale 84, I-00146 Roma (Italy); and others

    2014-09-20

    We present a broadband (∼0.5-79 keV) spectral and temporal analysis of multiple NuSTAR observations combined with archival Suzaku and Chandra data of NGC 4945, the brightest extragalactic source at 100 keV. We observe hard X-ray (>10 keV) flux and spectral variability, with flux variations of a factor of two on timescales of 20 ks. A variable primary continuum dominates the high-energy spectrum (>10 keV) in all states, while the reflected/scattered flux that dominates at E <10 keV stays approximately constant. From modeling the complex reflection/transmission spectrum, we derive a Compton depth along the line of sight of τ{sub Thomson} ∼ 2.9, and a global covering factor for the circumnuclear gas of ∼0.15. This agrees with the constraints derived from the high-energy variability, which implies that most of the high-energy flux is transmitted rather than Compton-scattered. This demonstrates the effectiveness of spectral analysis at constraining the geometric properties of the circumnuclear gas, and validates similar methods used for analyzing the spectra of other bright, Compton-thick active galactic nuclei (AGNs). The lower limits on the e-folding energy are between 200 and 300 keV, consistent with previous BeppoSAX, Suzaku, and Swift Burst Alert Telescope observations. The accretion rate, estimated from the X-ray luminosity and assuming a bolometric correction typical of type 2 AGN, is in the range ∼0.1-0.3 λ{sub Edd} depending on the flux state. The substantial observed X-ray luminosity variability of NGC 4945 implies that large errors can arise from using single-epoch X-ray data to derive L/L {sub Edd} values for obscured AGNs.

  4. Measurement of the 1s2l3l’ Dielectronic Recombination Emission Line in Li-Like Ar and Its Contribution to the Faint X-Ray Feature Found in the Stacked Spectrum of Galaxy Clusters

    Science.gov (United States)

    Gall, Amy Christina; Silwal, Roshani; Dreiling, Joan; Borovik, Alexander; Ajello, Marco; Gillaspy, John; Kilgore, Ethan; Ralchenko, Yuri; Takacs, Endre

    2016-06-01

    Driven by the recent detection of an unidentified emission line previously reported at 3.55-3.57 keV in a stacked spectrum of galaxy clusters, we investigated the resonant DR process in Li-like Ar as a possible source of, or contributor to, the emission line. The Li-like transition 1s22l-1s2l3l’ was suggested to produce a 3.62 keV photon [1] near the unidentified line at 3.57 keV and was the primary focus of our investigation. Apart from the mentioned transitions, we have found other features that can be possible contributors to the emission in this region. The Electron Beam Ion Trap at NIST was used to produce and trap the highly-charged ions of argon. The energy of the quasi-monoenergetic electron beam was incremented in steps of 15 eV to scan over all of the Li-like Ar DR resonances. A Johann-type crystal spectrometer and a solid-state germanium detector were used to take x-ray measurements perpendicular to the electron beam. The DR cross sections were measured and normalized to the well-known photoionization cross sections using radiative recombination peaks in the measured spectra. Corrections for different instrument and method related effects such as charge state balance, electron beam space charge, and charge exchange have been considered. Our high-resolution crystal spectra allowed the experimental separation of features that are less than 2 eV apart. We have used a collisional radiative model NOMAD [2] aided by atomic data calculations by FAC [3] to interpret our observations and account for the corrections and uncertainties. Experimental results were compared to the AtomDB theoretical emission lines used to fit the galaxy cluster spectra containing the unidentified 3.57 keV line. These data points can be added benchmarks in the database and used to accurately interpret spectra from current x-ray satellites, including Hitomi, Chandra, and XMM-Newton x-ray observatories.[1] Bulbul E. et al., 2014, ApJ, 789, 13[2] Ralchenko Yu. et al., 2014, JQSRT, 71

  5. Semiconductor X-ray detectors

    CERN Document Server

    Lowe, Barrie Glyn

    2014-01-01

    Identifying and measuring the elemental x-rays released when materials are examined with particles (electrons, protons, alpha particles, etc.) or photons (x-rays and gamma rays) is still considered to be the primary analytical technique for routine and non-destructive materials analysis. The Lithium Drifted Silicon (Si(Li)) X-Ray Detector, with its good resolution and peak to background, pioneered this type of analysis on electron microscopes, x-ray fluorescence instruments, and radioactive source- and accelerator-based excitation systems. Although rapid progress in Silicon Drift Detectors (SDDs), Charge Coupled Devices (CCDs), and Compound Semiconductor Detectors, including renewed interest in alternative materials such as CdZnTe and diamond, has made the Si(Li) X-Ray Detector nearly obsolete, the device serves as a useful benchmark and still is used in special instances where its large, sensitive depth is essential. Semiconductor X-Ray Detectors focuses on the history and development of Si(Li) X-Ray Detect...

  6. An X-ray variable absorber within the Broad Line Region in Fairall 51

    CERN Document Server

    Svoboda, Jiri; Guainazzi, Matteo; Longinotti, Anna Lia; Piconcelli, Enrico; Wilms, Joern

    2015-01-01

    Fairall 51 is a polar-scattered Seyfert 1 galaxy, a type of active galaxies believed to represent a bridge between unobscured type-1 and obscured type-2 objects. Fairall 51 has shown complex and variable X-ray absorption but only little is known about its origin. In our research, we observed Fairall 51 with the X-ray satellite Suzaku in order to constrain a characteristic time-scale of its variability. We performed timing and spectral analysis of four observations separated by 1.5, 2 and 5.5 day intervals. We found that the 0.5-50 keV broadband X-ray spectra are dominated by a primary power-law emission (with the photon index ~ 2). This emission is affected by at least three absorbers with different ionisations (log(xi) ~ 1-4). The spectrum is further shaped by a reprocessed emission, possibly coming from two regions -- the accretion disc and a more distant scattering region. The accretion disc emission is smeared by the relativistic effects, from which we measured the spin of the black hole as a ~ 0.8 (+-0.2...

  7. 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 $\

  8. IGRJ17361-4441: a possible new accreting X-ray binary in NGC6388

    CERN Document Server

    Bozzo, E; Stevens, J; Belloni, T M; Rodriguez, J; Hartog, P R den; Papitto, A; Kreykenbohm, I; Fontani, F; Gibaud, L

    2011-01-01

    IGRJ17361-4441 is a newly discovered INTEGRAL hard X-ray transient, located in the globular cluster NGC6388. We report here the results of the X-ray and radio observations performed with Swift, INTEGRAL, RXTE, and the Australia Telescope Compact Array (ATCA) after the discovery of the source on 2011 August 11. In the X-ray domain, IGRJ17361-4441 showed virtually constant flux and spectral parameters up to 18 days from the onset of the outburst. The broad-band (0.5-100 keV) spectrum of the source could be reasonably well described by using an absorbed power-law component with a high energy cut-off (N_H\\simeq0.8x10^(22) cm^(-2), {\\Gamma}\\simeq0.7-1.0, and E_cut\\simeq25 keV) and displayed some evidence of a soft component below \\sim2 keV. No coherent timing features were found in the RXTE data. The ATCA observation did not detect significant radio emission from IGRJ17361-4441, and provided the most stringent upper limit (rms 14.1 {\\mu}Jy at 5.5 GHz) to date on the presence of any radio source close to the NGC638...

  9. Discovery of X-rays from Mars with Chandra

    CERN Document Server

    Dennerl, K

    2002-01-01

    On 4 July 2001, X-rays from Mars were detected for the first time. The observation was performed with the ACIS-I detector onboard Chandra and yielded data of high spatial and temporal resolution, together with spectral information. Mars is clearly detected as an almost fully illuminated disk, with an indication of limb brightening at the sunward side, accompanied by some fading on the opposite side. The morphology and the X-ray luminosity of ~4 MW are fully consistent with fluorescent scattering of solar X-rays in the upper Mars atmosphere. The X-ray spectrum is dominated by a single narrow emission line, which is most likely caused by O-K_alpha fluorescence. No evidence for temporal variability is found. This is in agreement with the solar X-ray flux, which was almost constant during the observation. In addition to the X-ray fluorescence, there is evidence for an additional source of X-ray emission, indicated by a faint X-ray halo which can be traced to about three Mars radii, and by an additional component ...

  10. Evidence for a resonant cyclotron line in IGR J16493-4348 from the Swift-BAT hard X-ray survey

    CERN Document Server

    D'Aì, A; La Parola, V; Segreto, A; Di Salvo, T; Iaria, R; Robba, N R; 10.1051/0004-6361/201117035

    2012-01-01

    Resonant absorption cyclotron features are a key diagnostic tool to directly measure the strength of the magnetic field of accreting neutron stars. However, typical values for cyclotron features lie in the high-energy part of the spectrum between 20 keV and 50 keV, where detection is often damped by the low statistics from single pointed observations. We show that long-term monitoring campaign performed with Swift-BAT of persistently, but faint, accreting high-mass X-ray binaries is able to reveal in their spectra the presence of cyclotron features. We extracted the average Swift-BAT 15-150 keV spectrum from the 54 months long Swift-BAT survey of the high-mass X-ray source IGR J16493-4348. To constrain the broadband spectrum we used soft X-ray spectra from Swift-XRT and Suzaku pointed observations. We model the spectra using a set of phenomenological models usually adopted to describe the energy spectrum of accreting high-mass X-ray binaries; irrespective of the models we used, we found significant improvemen...

  11. X-ray diffraction apparatus

    International Nuclear Information System (INIS)

    The invention provides an x-ray diffraction apparatus permitting the rotation of the divergence sit in conjunction with the rotation of the x-ray irradiated specimen, whereby the dimensions of the x-ray irradiated portion of the specimen remain substantially constant during the rotation of the specimen. In a preferred embodiment, the divergence slit is connected to a structural element linked with a second structural element connected to the specimen such that the divergence slit rotates at a lower angular speed than the specimen

  12. Using the High Resolution X-ray Spectrum of PSR B0656+14 to Constrain the Chemical Composition of the Neutron Star Atmosphere

    CERN Document Server

    Marshall, H L

    2002-01-01

    Observations of PSR B0656+14 using the Chandra Low Energy Transmission Grating Spectrometer are presented. The zeroth order events are pulsed at an amplitude of 10 +/- 2% and the image may be slightly extended. The extended emission is modelled as a Gaussian with a FWHM of about 0.75", for a linear size (at a distance of 760 pc) of 8.5e15 cm. In the absence of systematic errors in the detector point spread function, the extended emission comprises <~ 50% of the observed flux in the 0.2-2.0 keV band, for a luminosity of <~ 3e32 erg/s. The spectrum is well modelled by a dominant blackbody with T = 8.0e5 +/- 3e4 K and a size of 22.5 +/- 2.1 km in addition to a harder component that is modelled as a hotter and much smaller blackbody. No significant absorption features are found in the spectrum that might be expected from ionization edges of H or He or bound-bound transitions of Fe in magnetized atmospheres. Such features are expected to be deep but could vary in position or strength with rotation phase. The...

  13. Total reflection X-ray fluorescence analysis

    International Nuclear Information System (INIS)

    In the past few years, total reflection X-ray flourescence analysis (TXRF) has found an increasing number of assignments and applications. Experience of trace element analysis using TXRF and examples of applications are already widespread. Therefore, users of TXRF had the opportunity of an intensive exchange of their experience at the 1st workshop on total reflection X-ray fluorescence analysis which took place on May 27th and 28th 1986 at the GKSS Research Centre at Geesthacht. In a series of lectures and discussions dealing with the analytical principle itself, sample preparation techniques and applications as well as comuter programs for spectrum evaluation, the present state of development and the range of applications were outlined. 3 studies out of a total of 14 were included separately in the INIS and ENERGY databases. With 61 figs., 12 tabs

  14. Recent Advances in X-ray Observations of Cataclysmic Variables

    OpenAIRE

    Mukai, K.

    2004-01-01

    A personal selection of noteworthy X-ray results on CVs are presented, with emphasis on XMM-Newton and Chandra observations. Progressing roughly from broad-band view to narrow-band, high spectral resolution studies, I summarize: the energy balance of polars; X-ray confirmation of IPs; eclipses in non-magnetic CVs; search for magnetism in "non-magnetic" CVs; multi-temperature plasma emission from the boundary layer; complex absorption in magnetic CVs; temperature and density diagnostics; and X...

  15. Duodenal X-ray diagnostics

    International Nuclear Information System (INIS)

    The publication provides an overview of duodenal X-ray diagnostics with the aid of barium meals in 1362 patients. The introducing paragraphs deal with the topographic anatomy of the region and the methodics of X-ray investigation. The chapter entitled ''processes at the duodenum itself'' describes mainly ulcers, diverticula, congenital anomalies, tumors and inflammations. The neighbourhood processes comprise in the first place diseases having their origin at the pancreas and bile ducts. As a conclusion, endoscopic rectograde cholangio-pancreaticography and percutaneous transhepatic cholangiography are pointed out as advanced X-ray investigation methods. In the annex of X-ray images some of the described phenomena are shown in exemplary manner. (orig./MG)

  16. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... like a photographic negative). Today, most images are digital files that are stored electronically. These stored images ... and places the x-ray film holder or digital recording plate under the table in the area ...

  17. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... pregnant. Many imaging tests are not performed during pregnancy so as not to expose the fetus to ... See the Safety page for more information about pregnancy and x-rays. top of page What does ...

  18. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... the baby. See the Safety page for more information about pregnancy and x-rays. top of page ... procedure varies. See the Safety page for more information about radiation dose. Women should always inform their ...

  19. X-ray microtomographic scanners

    Energy Technology Data Exchange (ETDEWEB)

    Syryamkin, V. I., E-mail: klestov-simon@mail.ru; Klestov, S. A., E-mail: klestov-simon@mail.ru [National Research Tomsk State University, Tomsk, 634050 (Russian Federation)

    2015-11-17

    The article studies the operating procedures of an X-ray microtomographic scanner and the module of reconstruction and analysis 3D-image of a test sample in particular. An algorithm for 3D-image reconstruction based on image shadow projections and mathematical methods of the processing are described. Chapter 1 describes the basic principles of X-ray tomography and general procedures of the device developed. Chapters 2 and 3 are devoted to the problem of resources saving by the system during the X-ray tomography procedure, which is achieved by preprocessing of the initial shadow projections. Preprocessing includes background noise removing from the images, which reduces the amount of shadow projections in general and increases the efficiency of the group shadow projections compression. In conclusion, the main applications of X-ray tomography are presented.

  20. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... top of page What are the benefits vs. risks? Benefits Bone x-rays are the fastest and ... in the typical diagnostic range for this exam. Risks There is always a slight chance of cancer ...

  1. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... can be taken to the patient in a hospital bed or the emergency room. The x-ray ... and international radiology protection organizations continually review and update the technique standards used by radiology professionals. Modern ...

  2. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... the patient in a hospital bed or the emergency room. The x-ray tube is connected to ... equipment is relatively inexpensive and widely available in emergency rooms, physician offices, ambulatory care centers, nursing homes ...

  3. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... or in bones. top of page How should I prepare? Most bone x-rays require no special ... to 10 minutes. top of page What will I experience during and after the procedure? A bone ...

  4. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... the body absorb the x-rays in varying degrees. Dense bone absorbs much of the radiation while ... is further reviewed by committees from the American College of Radiology (ACR) and the Radiological Society of ...

  5. Dental X-ray apparatus

    International Nuclear Information System (INIS)

    Intra-oral dental X-ray apparatus for panoramic dental radiography is described in detail. It comprises an electron gun having an elongated tubular target carrier extending into the patient's mouth. The carrier supports an inclined target for direction of an X-ray pattern towards a film positioned externally of the patient's mouth. Image definition is improved by a focusing anode which focuses the electron beam into a sharp spot (0.05 to 0.10 mm diameter) on the target. The potential on the focusing anode is adjustable to vary the size of the spot. An X-ray transmitting ceramic (oxides of Be, Al and Si) window is positioned adjacent to the front face of the target. The electron beam can be magnetically deflected to change the X-ray beam direction. (author)

  6. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... during x-ray examinations to use the lowest radiation dose possible while producing the best images for evaluation. National and international radiology protection organizations continually review and update the technique standards ...

  7. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... technologist, an individual specially trained to perform radiology examinations, positions the patient on the x-ray table ... bone is forming), for comparison purposes. When the examination is complete, you may be asked to wait ...

  8. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... replacement and fracture reductions. look for injury, infection, arthritis , abnormal bone growths and bony changes seen in ... injuries, including fractures, and joint abnormalities, such as arthritis. X-ray equipment is relatively inexpensive and widely ...

  9. X-Ray Assembler Data

    Data.gov (United States)

    U.S. Department of Health & Human Services — Federal regulations require that an assembler who installs one or more certified components of a diagnostic x-ray system submit a report of assembly. This database...

  10. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... a large photographic negative). Today, most images are digital files that are stored electronically. These stored images ... and places the x-ray film holder or digital recording plate under the table in the area ...

  11. X-ray shout echoing through space

    Science.gov (United States)

    2004-01-01

    , the team in Leicester have determined accurately the distance to the dust sheets by measuring the size of the expanding rings. The nearest dust sheet is located 2900 light years away and is probably part of the Gum nebula, a bubble of hot gas resulting from many supernova explosions. The other dust layer is about 4500 light years away. Understanding how dust is distributed in our Galaxy is important because dust favours the collapse of cool gas clouds, which can then form stars and planets. Knowing where dust is located helps astronomers to determine where star and planet formation is likely to occur. Expanding X-ray dust scattering rings, such as those around GRB 031203, have never been seen before. Slower-moving rings, caused by a similar effect, have been seen in visible light around a very few exploding stars, mostly supernovae. The expanding rings also provide much needed information on the gamma-ray burst itself. Gamma-ray bursts are the most powerful explosive events in the Universe, but astronomers are still trying to understand the mystery that surrounds their origin. Some occur with the supernova explosion of a massive star when it has used up all of its fuel, although only stars which have lost their outer layers and which collapse to make a black hole seem able to make a gamma-ray burst. The delayed X-rays from the echo of GRB 031203 are very useful because they tell astronomers how bright the burst was in the X-ray spectrum when it went off on 3 December. The only direct data available from that moment are those obtained by ESA's Integral observatory in the gamma-ray range. "XMM-Newton's measurements are thus crucial to better understand the nature of the burst," said Dr. Fred Jansen, XMM-Newton's project scientist. "The more details we gather of the burst, the more we can learn on how black holes are made." Today, ESA's Integral and XMM-Newton observatories provide astronomers with their most powerful facilities for studying gamma-ray bursts. In 2004 a

  12. X-ray spectral diagnostics of activity in massive stars

    CERN Document Server

    Cohen, David H; Leutenegger, Maurice A

    2010-01-01

    X-rays give direct evidence of instabilities, time-variable structure, and shock heating in the winds of O stars. The observed broad X-ray emission lines provide information about the kinematics of shock-heated wind plasma, enabling us to test wind-shock models. And their shapes provide information about wind absorption, and thus about the wind mass-loss rates. Mass-loss rates determined from X-ray line profiles are not sensitive to density-squared clumping effects, and indicate mass-loss rate reductions of factors of 3 to 6 over traditional diagnostics that suffer from density-squared effects. Broad-band X-ray spectral energy distributions also provide mass-loss rate information via soft X-ray absorption signatures. In some cases, the degree of wind absorption is so high that the hardening of the X-ray SED can be quite significant. We discuss these results as applied to the early O stars zeta Pup (O4 If), 9 Sgr (O4 V((f))), and HD 93129A (O2 If*).

  13. Research of multilayers in EUV,soft X-ray and X-ray

    Institute of Scientific and Technical Information of China (English)

    WANG Zhan-shan; LI Cun-xia; WU Yong-rong; WANG Bei; QIN Shu-jin; CHEN Ling-yan; WANG Feng-li; ZHANG Zhong; WANG Hong-chang; WU Wen-juan; ZHANG Shu-min; XU Yao; GU Zhong-xiang; CHENG Xin-bin

    2005-01-01

    To develop beam splitters for soft X-ray laser Michelson interferometer at 13.9 nm, Mo/Si multilayers of 100 nm thickness deposited on both sides of silicon nitride were fabricated by using DC magnetron sputtering. Initial evaluation of their reflectivity and transmission showed that reflectivity and transmission were above 10% and 25%. The broadband analyzers have been designed, fabricated and characterized for 13~20 nm polarization measurements. The measured results are in good agreement with the design. The supermirrors with different angular intervals at 0.154 nm have been designed, fabricated and characterized.

  14. Surface-Enhanced X-Ray Fluorescence

    Science.gov (United States)

    Anderson, Mark

    2010-01-01

    Surface-enhanced x-ray fluorescence (SEn-XRF) spectroscopy is a form of surface- enhanced spectroscopy that was conceived as a means of obtaining greater sensitivity in x-ray fluorescence (XRF) spectroscopy. As such, SEn-XRF spectroscopy joins the ranks of such other, longer-wavelength surface-enhanced spectroscopies as those based on surface-enhanced Raman scattering (SERS), surface-enhanced resonance Raman scattering (SERRS), and surfaceenhanced infrared Raman absorption (SEIRA), which have been described in previous NASA Tech Briefs articles. XRF spectroscopy has been used in analytical chemistry for determining the elemental compositions of small samples. XRF spectroscopy is rapid and quantitative and has been applied to a variety of metal and mineralogical samples. The main drawback of XRF spectroscopy as practiced heretofore is that sensitivity has not been as high as required for some applications. In SEn-XRF as in the other surface-enhanced spectroscopies, one exploits several interacting near-field phenomena, occurring on nanotextured surfaces, that give rise to local concentrations of incident far-field illumination. In this case, the far-field illumination comes from an x-ray source. Depending on the chemical composition and the geometry of a given nanotextured surface, these phenomena could include the lightning-rod effect (concentration of electric fields at the sharpest points on needlelike surface features), surface plasmon resonances, and grazing incidence geometric effects. In the far field, the observable effect of these phenomena is an increase in the intensity of the spectrum of interest - in this case, the x-ray fluorescence spectrum of chemical elements of interest that may be present within a surface layer at distances no more than a few nanometers from the surface.

  15. Soft X-ray Absorption Edges in LMXBs

    Science.gov (United States)

    2004-01-01

    The XMM observation of LMC X-2 is part of our program to study X-ray absorption in the interstellar medium (ISM). This program includes a variety of bright X-ray binaries in the Galaxy as well as the Magellanic Clouds (LMC and SMC). LMC X-2 is located near the heart of the LMC. Its very soft X-ray spectrum is used to determine abundance and ionization fractions of neutral and lowly ionized oxygen of the ISM in the LMC. The RGS spectrum so far allowed us to determine the O-edge value to be for atomic O, the EW of O-I in the ls-2p resonance absorption line, and the same for O-II. The current study is still ongoing in conjunction with other low absorption sources like Sco X-1 and the recently observed X-ray binary 4U 1957+11.

  16. Accelerator x-ray sources

    CERN Document Server

    Talman, Richard

    2007-01-01

    This first book to cover in-depth the generation of x-rays in particle accelerators focuses on electron beams produced by means of the novel Energy Recovery Linac (ERL) technology. The resulting highly brilliant x-rays are at the centre of this monograph, which continues where other books on the market stop. Written primarily for general, high energy and radiation physicists, the systematic treatment adopted by the work makes it equally suitable as an advanced textbook for young researchers.

  17. X-ray fluorescence holography

    CERN Document Server

    Hayashi, K; Takahashi, Y

    2003-01-01

    X-ray fluorescence holography (XFH) is a new structural analysis method of determining a 3D atomic arrangement around fluorescing atoms. We developed an XFH apparatus using advanced X-ray techniques and succeeded in obtaining high-quality hologram data. Furthermore, we introduced applications to the structural analysis of a thin film and the environment around dopants and, discussed the quantitative analysis of local lattice distortion. (author)

  18. Electromechanical x-ray generator

    Energy Technology Data Exchange (ETDEWEB)

    Watson, Scott A; Platts, David; Sorensen, Eric B

    2016-05-03

    An electro-mechanical x-ray generator configured to obtain high-energy operation with favorable energy-weight scaling. The electro-mechanical x-ray generator may include a pair of capacitor plates. The capacitor plates may be charged to a predefined voltage and may be separated to generate higher voltages on the order of hundreds of kV in the AK gap. The high voltage may be generated in a vacuum tube.

  19. Uhuru observations of 4U 1608-52 - The 'steady' X-ray source associated with the X-ray burst source in Norma

    Science.gov (United States)

    Tananbaum, H.; Chaisson, L. J.; Forman, W.; Jones, C.; Matilsky, T. A.

    1976-01-01

    Data are presented for the X-ray source 4U 1608-52, summarizing its light curve, location, and spectral parameters. Evidence is presented showing that this source is the 'steady' X-ray counterpart of the X-ray burst source in Norma. The spectrum of the 'steady' source is compared with the spectrum observed during two bursts, and it is noted that there is substantially more low-energy absorption during the bursts. The 'steady' source spectral data are used to examine the optical data, and it is concluded that if the X-ray spectrum is thermal, then a globular-cluster counterpart probably would have been detected (whereas none has been). Further X-ray and optical observations are suggested for this source, since an optical identification may be central in determining whether all X-ray bursts have a common origin and if this origin requires a globular-cluster environment.

  20. Monte Carlo simulation of the interaction of X-ray spectrum with human tissue, in the energies range of diagnostic radiology; Simulacion Monte Carlo de la interaccion del espectro de rayos X con el tejido humano, en el rango de energias de diagnostico radiologico

    Energy Technology Data Exchange (ETDEWEB)

    Cayllahua Q, L. F.; Apaza V, G.; Vega R, J. L., E-mail: fredycayllahua@gmail.com [Universidad Nacional de San Agustin, Area de Fisica Medica, Av. Independencia s/n, Arequipa (Peru)

    2015-10-15

    Full text: This paper is an approach to an increasingly complete knowledge about the nature of the processes that occur during a simple examination of radiological diagnosis; know as X-rays are produced and how they will put their energy into the tissue of patients when they are subjected to an examination of radiological diagnosis. First, using the MCNP code an X-rays tube was simulated, where electrons are emitted from a filament (cathode) which travel a certain distance with a certain kinetic energy and then be stopped suddenly in the tungsten target. The X-rays emitted as a result of this interaction, are previously filtered through the inherent filter of Pyrex glass and then by a thin aluminum foil before quantification as an X-rays spectrum. 6 spectra (for 60, 80, 100, 120 and 140 KeV) were obtained. Second, using the Penelope code was simulated the interaction of the X-rays spectrum, obtained in the first part with human tissue, putting as simile of human tissue water phantoms of different thicknesses. As final result: dose of energy deposited (in 2 and 3-dimensional) and reflected, absorbed and transmitted photons spectra. (Author)

  1. X-ray diagnostic apparatus

    International Nuclear Information System (INIS)

    A falling load type X-ray diagnostic apparatus comprises a low voltage power source, AC-DC converting means connected to the low voltage power source so as to apply a rectified low DC voltage, chopping means connected to the AC-DC converting means and chopping said DC voltage into a low AC voltage, high voltage applying means for transforming said low AC voltage into a high AC voltage, said high AC voltage being applied as a tube voltage to an X-ray tube from which X-rays are irradiated toward an object to be examined, means for controlling a filament heating power of the X-ray tube, programming means for supplying a control signal to said filament heating control means so as to reduce the emission current of said X-ray tube during the irradiation, and chopper control means for controlling the chopping ratio of said chopping means by evaluating said rectified DC voltage with a preset tube voltage generated in said programming means, said programming means compensating said tube voltage by receiving said control signal in such a manner that said tube voltage is maintained substantially constant during the irradiation by varying said preset tube voltage so as to control the chopping ratio based upon the reduction of the filament heating power for the X-ray tube

  2. Low energy (soft) x rays

    International Nuclear Information System (INIS)

    Dosimetry of low-energy (soft) X rays produced by the SOFTEX Model CMBW-2 was performed using Nuclear Associates Type 30 - 330 PTW, Exradin Type A2, and Shonka-Wyckoff ionization chambers with a Keithley Model 602 electrometer. Thermoluminescent (BeO chip) dosimeters were used with a Harshaw Detector 2000-A and Picoammeter-B readout system. Beam quality measurements were made using aluminum absorbers; exposure rates were assessed by the current of the X-ray tube and by exposure times. Dose distributions were established, and the average factors for non-uniformity were calculated. The means of obtaining accurate absorbed and exposed doses using these methods are discussed. Survival of V79 cells was assessed by irradiating them with soft X rays, 200 kVp X rays, and 60Co gamma rays. The relative biological effectiveness (RBE) values for soft X rays with 0, 0.2, 0.7 mm added thicknesses of aluminum were 1.6, which were compared to 60Co. The RBE of 200 kVp X rays relative to 60Co was 1.3. Results of this study are available for reference in future RERF studies of cell survival. (author)

  3. Center for X-Ray Optics, 1992

    International Nuclear Information System (INIS)

    This report discusses the following topics: Center for X-Ray Optics; Soft X-Ray Imaging wit Zone Plate Lenses; Biological X-Ray microscopy; Extreme Ultraviolet Lithography for Nanoelectronic Pattern Transfer; Multilayer Reflective Optics; EUV/Soft X-ray Reflectometer; Photoemission Microscopy with Reflective Optics; Spectroscopy with Soft X-Rays; Hard X-Ray Microprobe; Coronary Angiography; and Atomic Scattering Factors

  4. Solar Intensity X-ray and particle Spectrometer (SIXS)

    Science.gov (United States)

    Huovelin, J.; Vainio, R.; Andersson, H.; Valtonen, E.; Alha, L.; Mälkki, A.; Grande, M.; Fraser, G. W.; Kato, M.; Koskinen, H.; Muinonen, K.; Näränen, J.; Schmidt, W.; Syrjäsuo, M.; Anttila, M.; Vihavainen, T.; Kiuru, E.; Roos, M.; Peltonen, J.; Lehti, J.; Talvioja, M.; Portin, P.; Prydderch, M.

    2010-01-01

    The Solar Intensity X-ray and particle Spectrometer (SIXS) on the BepiColombo Mercury Planetary Orbiter (MPO) will investigate the direct solar X-rays, and energetic protons and electrons which pass the Spacecraft on their way to the surface of Mercury. These measurements are vitally important for understanding quantitatively the processes that make Mercury's surface glow in X-rays, since all X-rays from Mercury are due to interactions of the surface with incoming highly energetic photons and space particles. The X-ray emission of Mercury's surface will be analysed to understand its structure and composition. SIXS data will also be utilised for studies of the solar X-ray corona, flares, solar energetic particles, and the magnetosphere of Mercury, and for providing information on solar eruptions to other BepiColombo instruments. SIXS consists of two detector subsystems. The X-ray detector system includes three identical GaAs PIN detectors which measure the solar spectrum at 1-20 keV energy range, and their combined field-of-view covers ˜1/4 of the whole sky. The particle detector system consists of an assembly including a cubic central CsI(Tl) scintillator detector with five of its six surfaces covered by a thin Si detector, which together perform low-resolution particle spectroscopy with a rough angular resolution over a field-of-view covering ˜1/4 of the whole sky. The energy range of detected particle spectra is 0.1-3 MeV for electrons and 1-30 MeV for protons. A major task for the SIXS instrument is the measurement of solar X-rays on the dayside of Mercury's surface to enable modeling of X-ray fluorescence and scattering on the planet's surface. Since highly energetic particles are expected to also induce a significant amount of X-ray emission via particle-induced X-ray emission (PIXE) and bremsstrahlung when they are absorbed by the solid surface of the planet Mercury, SIXS performs measurements of fluxes and spectra of protons and electrons. SIXS performs

  5. NuSTAR Study of Hard X-Ray Morphology and Spectroscopy of PWN G21.5-0.9

    Science.gov (United States)

    Nynka, Melania; Hailey, Charles J.; Reynolds, Stephen P.; An, Hongjun; Baganoff, Frederick K.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Gotthelf, Eric V.; Grefenstette, Brian W.; Harrison, Fiona A.; Krivonos, Roman; Madsen, Kristin K.; Mori, Kaya; Perez, Kerstin; Stern, Daniel; Wik, Daniel R.; Zhang, William W.; Zoglauer, Andreas

    2014-07-01

    We present NuSTAR high-energy X-ray observations of the pulsar wind nebula (PWN)/supernova remnant G21.5-0.9. We detect integrated emission from the nebula up to ~40 keV, and resolve individual spatial features over a broad X-ray band for the first time. The morphology seen by NuSTAR agrees well with that seen by XMM-Newton and Chandra below 10 keV. At high energies, NuSTAR clearly detects non-thermal emission up to ~20 keV that extends along the eastern and northern rim of the supernova shell. The broadband images clearly demonstrate that X-ray emission from the North Spur and Eastern Limb results predominantly from non-thermal processes. We detect a break in the spatially integrated X-ray spectrum at ~9 keV that cannot be reproduced by current spectral energy distribution models, implying either a more complex electron injection spectrum or an additional process such as diffusion compared to what has been considered in previous work. We use spatially resolved maps to derive an energy-dependent cooling length scale, L(E)vpropEm with m = -0.21 ± 0.01. We find this to be inconsistent with the model for the morphological evolution with energy described by Kennel & Coroniti. This value, along with the observed steepening in power-law index between radio and X-ray, can be quantitatively explained as an energy-loss spectral break in the simple scaling model of Reynolds, assuming particle advection dominates over diffusion. This interpretation requires a substantial departure from spherical magnetohydrodynamic, magnetic-flux-conserving outflow, most plausibly in the form of turbulent magnetic-field amplification.

  6. NuSTAR Study of Hard X-ray Morphology and Spectroscopy G21.5-0.9

    Science.gov (United States)

    Nynka, Melania; Hailey, Charles J.; Reynolds, Stephen P.; An, Hongjun; Baganoff, Frederick K.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Gotthelf, Eric V.; Grefenstette, Brian W.; Harrison, Fiona A.; Krivonos, Roman; Madsen, Kristin K.; Mori, Kaya; Perez, Kerstin; Stern, Daniel; Wik, Daniel R.; Zhang, William W.; Zoglauer, Andreas

    2014-01-01

    We present NuSTAR high-energy X-ray observations of the pulsar wind nebula (PWN)/supernova remnant G21.5-0.9. We detect integrated emission from the nebula up to approx. 40 keV, and resolve individual spatial features over a broad X-ray band for the first time. The morphology seen by NuSTAR agrees well with that seen by XMM-Newton and Chandra below 10 keV. At high energies, NuSTAR clearly detects non-thermal emission up to approx. 20 keV that extends along the eastern and northern rim of the supernova shell. The broadband images clearly demonstrate that X-ray emission from the North Spur and Eastern Limb results predominantly from non-thermal processes. We detect a break in the spatially integrated X-ray spectrum at approx. 9 keV that cannot be reproduced by current spectral energy distribution models, implying either a more complex electron injection spectrum or an additional process such as diffusion compared to what has been considered in previous work. We use spatially resolved maps to derive an energy-dependent cooling length scale, E(sup m) is directly proportional to L(E) with m = -0.21 plus or minus 0.01. We find this to be inconsistent with the model for the morphological evolution with energy described by Kennel & Coroniti. This value, along with the observed steepening in power-law index between radio and X-ray, can be quantitatively explained as an energy-loss spectral break in the simple scaling model of Reynolds, assuming particle advection dominates over diffusion. This interpretation requires a substantial departure from spherical magnetohydrodynamic, magnetic-flux-conserving outflow, most plausibly in the form of turbulent magnetic-field amplification.

  7. Swift J0525.6+2416 and IGR J04571+4527: two new hard X-ray selected magnetic cataclysmic variables identified with XMM-Newton

    CERN Document Server

    Bernardini, F; Mukai, K; Israel, G; Falanga, M; Ramsay, G; Masetti, N

    2015-01-01

    IGR J04571+4527 and Swift J0525.6+2416 are two hard X-ray sources detected in the Swift/BAT and INTEGRAL/IBIS surveys. They were proposed to be magnetic cataclysmic variables of the Intermediate Polar (IP) type, based on optical spectroscopy. IGR J04571+4527 also showed a 1218 s optical periodicity, suggestive of the rotational period of a white dwarf, further pointing towards an IP classification. We here present detailed X-ray (0.3-10 keV) timing and spectral analysis performed with XMM-Newton, complemented with hard X-ray coverage (15-70 keV) from Swift/BAT. These are the first high signal to noise observations in the soft X-ray domain for both sources, allowing us to identify the white dwarf X-ray spin period of Swift J0525.6+2416 (226.28 s), and IGR J04571+4527 (1222.6 s). A model consisting of multi-temperature optically thin emission with complex absorption adequately fits the broad-band spectrum of both sources. We estimate a white dwarf mass of about 1.1 and 1.0 solar masses for IGR J04571+4527 and S...

  8. The very soft X-ray emission of X-ray-faint early-type galaxies

    Science.gov (United States)

    Pellegrini, S.; Fabbiano, G.

    1994-01-01

    A recent reanaylsis of Einstein data, and new ROSAT observations, have revealed the presence of at least two components in the X-ray spectra of X-ray faint early-type galaxies: a relatively hard component (kT greater than 1.5 keV), and a very soft component (kT approximately 0.2-0.3 keV). In this paper we address the problem of the nature of the very soft component and whether it can be due to a hot interstellar medium (ISM), or is most likely originated by the collective emission of very soft stellar sources. To this purpose, hydrodynamical evolutionary sequences for the secular behavior of gas flows in ellipticals have been performed, varying the Type Ia supernovae rate of explosion, and the dark matter amount and distribution. The results are compared with the observational X-ray data: the average Einstein spectrum for six X-ray faint early-type galaxies (among which are NGC 4365 and NGC 4697), and the spectrum obtained by the ROSAT pointed observation of NGC 4365. The very soft component could be entirely explained with a hot ISM only in galaxies such as NGC 4697, i.e., when the depth of the potential well-on which the average ISM temperature strongly depends-is quite shallow; in NGC 4365 a diffuse hot ISM would have a temperature larger than that of the very soft component, because of the deeper potential well. So, in NGC 4365 the softest contribution to the X-ray emission comes certainly from stellar sources. As stellar soft X-ray emitters, we consider late-type stellar coronae, supersoft sources such as those discovered by ROSAT in the Magellanic Clouds and M31, and RS CVn systems. All these candidates can be substantial contributors to the very soft emission, though none of them, taken separately, plausibly accounts entirely for its properties. We finally present a model for the X-ray emission of NGC 4365, to reproduce in detail the results of the ROSAT pointed observation, including the Position Sensitive Proportional Counter (PSPC) spectrum and radial

  9. Characterization of an indirect X-ray imaging detector by simulation and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Doshi, C.; Riessen, G. van; Balaur, E. [Department of Physics, La Trobe University, Victoria 3086 (Australia); Centre of Excellence for Coherent X-ray Science, La Trobe University, Victoria 3086 (Australia); Jonge, M.D. de [Australian Synchrotron, Victoria 3168 (Australia); Peele, A.G. [Department of Physics, La Trobe University, Victoria 3086 (Australia); Centre of Excellence for Coherent X-ray Science, La Trobe University, Victoria 3086 (Australia); Australian Synchrotron, Victoria 3168 (Australia); Centre of Excellence for Advanced Molecular Imaging, Australian Synchrotron, Victoria 3168 (Australia)

    2015-01-15

    We describe a comprehensive model of a commercial indirect X-ray imaging detector that accurately predicts the detector point spread function and its dependence on X-ray energy. The model was validated by measurements using monochromatic synchrotron radiation and extended to polychromatic X-ray sources. Our approach can be used to predict the performance of an imaging detector and can be used to optimize imaging experiments with broad-band X-ray sources. - Highlights: • We modeled the point spread function of an indirect X-ray imaging detector. • The effects of optical coupling between detector components were included. • The model was validated with monochromatic and polychromatic X-ray source. • The geometrical arrangement for optimal detector resolution was identified.

  10. Dental X-ray apparatus

    International Nuclear Information System (INIS)

    Intra-oral X-ray apparatus which reduces the number of exposures necessary to obtain panoramic dental radiographs is described in detail. It comprises an electron gun, a tubular target carrier projecting from the gun along the beam axis and carrying at its distal end a target surrounded by a shield of X-ray opaque material. This shield extends forward and laterally of the target and has surfaces which define a wedge or cone-shaped radiation pattern delimited vertically by the root tips of the patient's teeth. A film holder is located externally of the patient's mouth. A disposable member can fit on the target carrier to depress the patient's tongue out of the radiation pattern and to further shield the roof of the mouth. The electron beam can be magnetically deflected to change the X-ray beam direction. (author)

  11. Near-Infrared Spectroscopy of Faint Discrete X-ray Point Sources Constituting the Galactic Ridge X-ray Emission

    CERN Document Server

    Morihana, Kumiko; Dubath, Pierre; Yoshida, Tessei; Suzuki, Kensuke; Ebisawa, Ken

    2016-01-01

    The Galactic Ridge X-ray Emission (GRXE) is apparently extended X-ray emission along the Galactic Plane. The X-ray spectrum is characterized by hard continuum with a strong Fe K emission feature in the 6-7 keV band. A substantial fraction (~80%) of the GRXE in the Fe band was resolved into point sources by deep Chandra imaging observations, thus GRXE is mostly composed of dim Galactic X-ray point sources at least in this energy band. To investigate the populations of these dim X-ray point sources, we carried out Near-Infrared (NIR) follow-up spectroscopic observations in two deep Chandra fields located in the Galactic plane at (l,b)=(0.1{\\arcdeg}, -1.4{\\arcdeg}) and (28.5{\\arcdeg}, 0.0{\\arcdeg}) using NTT/SofI and Subaru/MOIRCS. We obtained well-exposed NIR spectra from 65 objects and found that there are three main classes of Galactic sources based on the X-ray color and NIR spectral features: those having (A) hard X-ray spectra and NIR emission features such as HI(Br{\\gamma}), HeI, and HeII (2 objects), (B)...

  12. X-ray properties of BzK-selected galaxies in the deepest X-ray fields

    CERN Document Server

    Rangel, Cyprian; Laird, Elise; Orange, Philip

    2012-01-01

    We investigate the X-ray properties of BzK-selected galaxies at z $\\sim$ 2 using deep X-ray data in the Chandra Deep Field South and North (CDFS and CDFN). Of these we directly detect in X-rays 49 sBzKs in CDFS and 32 sBzKs in CDFN. Stacking the undetected sources also reveals a significant X-ray signal. Investigating the X-ray detection rate and stacked flux versus the IR excess parameter (i.e. SFRtotal/SFRUV,corr), we find no strong evidence for an increased X-ray detection rate, or a harder X-ray spectrum in IR Excess sBzKs. This is particularly the case when one accounts for the strong correlation between the IR excess parameter and the bolometric IR luminosity (LIR), e.g. when controlling for LIR, the IR Non-Excess sBzKs show a detection rate at least as high. While both direct detections and stacking suggest that the AGN fraction in sBzK galaxies is high, there is no clear evidence for widespread Compton thick activity in either the sBzK population generally, or the IR Excess sBzK subsample. The very ha...

  13. X-ray imaging: Perovskites target X-ray detection

    Science.gov (United States)

    Heiss, Wolfgang; Brabec, Christoph

    2016-05-01

    Single crystals of perovskites are currently of interest to help fathom fundamental physical parameters limiting the performance of perovskite-based polycrystalline solar cells. Now, such perovskites offer a technology platform for optoelectronic devices, such as cheap and sensitive X-ray detectors.

  14. Quantum SASE Regime for X-Ray FEL

    CERN Document Server

    Avetissian, H K

    2005-01-01

    For the X-ray FEL if the amplifying photon energy is larger or comparable to resonance widths caused by an electron beam spreads or by the finite interaction length then the quantum effects may play a significant role [1] and the generation process shifts from the classical to the quantum regime. The recent advancement of high brightness particle and laser beams technology makes achievable the fulfillment of these conditions in the scheme of X-ray Backscatter Compton laser. In this work we consider in general the SASE X-ray FEL in the quantum regime of amplification arising from the self-consistent set of the Maxwell and relativistic quantum kinetic equations. It is shown a considerable increase in start-up and narrowing of the spectrum of the SASE power for amplifying X-ray frequencies compared with the classical SASE regime.

  15. Constraining MHD Disk-Winds with X-ray Absorbers

    Science.gov (United States)

    Fukumura, Keigo; Tombesi, F.; Shrader, C. R.; Kazanas, D.; Contopoulos, J.; Behar, E.

    2014-01-01

    From the state-of-the-art spectroscopic observations of active galactic nuclei (AGNs) the robust features of absorption lines (e.g. most notably by H/He-like ions), called warm absorbers (WAs), have been often detected in soft X-rays (UFOs) whose physical condition is much more extreme compared with the WAs. Motivated by these recent X-ray data we show that the magnetically- driven accretion-disk wind model is a plausible scenario to explain the characteristic property of these X-ray absorbers. As a preliminary case study we demonstrate that the wind model parameters (e.g. viewing angle and wind density) can be constrained by data from PG 1211+143 at a statistically significant level with chi-squared spectral analysis. Our wind models can thus be implemented into the standard analysis package, XSPEC, as a table spectrum model for general analysis of X-ray absorbers.

  16. UV and X-ray Variability of Blazars

    Indian Academy of Sciences (India)

    Alok C. Gupta

    2011-03-01

    It is well established that the blazars show flux variations in the complete electromagnetic (EM) spectrum on all possible time scales ranging from a few tens of minutes to several years. Here we report the review of various UV and X-ray flux variability properties of blazars. Our analysis show that UV variability amplitude is smaller than X-rays, mostly soft X-rays hardness ratio show correlations with blazar luminosity and different modes of variability might be operating for different time scales and epochs. Quasi periodic oscillations are seen on a few occasions in blazars, higher fraction of high energy peaked blazars show intra day and short term variabilities in X-rays but variability duty cycle is much less in optical bands on intra day time scale compared to low energy peaked blazars. But these results are yet to be established.

  17. X-ray Fluorescent Fe Kalpha Lines from Stellar Photospheres

    CERN Document Server

    Drake, Jeremy J; Swartz, Douglas A

    2007-01-01

    X-ray spectra from stellar coronae are reprocessed by the underlying photosphere through scattering and photoionization events. While reprocessed X-ray spectra reaching a distant observer are at a flux level of only a few percent of that of the corona itself, characteristic lines formed by inner shell photoionization of some abundant elements can be significantly stronger. The emergent photospheric spectra are sensitive to the distance and location of the fluorescing radiation and can provide diagnostics of coronal geometry and abundance. Here we present Monte Carlo simulations of the photospheric Kalpha doublet arising from quasi-neutral Fe irradiated by a coronal X-ray source. Fluorescent line strengths have been computed as a function of the height of the radiation source, the temperature of the ionising X-ray spectrum, and the viewing angle. We also illustrate how the fluorescence efficiencies scale with the photospheric metallicity and the Fe abundance. Based on the results we make three comments: (1) fl...

  18. Hard x-ray spectrometers for NIF (abstract)

    Science.gov (United States)

    Seely, John; Holland, Glenn; Brown, Charles; Deslattes, Richard; Hudson, Lawrence; Bell, Perry; Miller, Michael; Back, Christina

    2001-01-01

    A National Ignition Facility (NIF) core diagnostic instrument has been designed and will be fabricated to record x-ray spectra in the 1.2-20 keV energy range. The high-energy electronic x-ray instrument has four reflection crystals with overlapping coverage of 1.2-10.9 keV and one transmission crystal covering 8.6-20 keV. The spectral resolving power varies from approximately 1000 at low energies to 315 at 20 keV. The spectrum produced by each crystal is recorded by a modified commercial dental x-ray charge coupled device (CCD) detector. The scintillators on the CCD detectors are optimized for the energy ranges. A one-channel x-ray spectrometer, using one transmission crystal covering 12-60 keV, will be fabricated for the OMEGA laser facility. The transmission crystal spectrometers are based on instruments originally designed at National Institute for Standards and Technology for the purpose of characterizing the x-ray flux from medical radiography sources. Utilizing one of those instruments and a commercial dental x-ray CCD detector, x-ray images were recorded using a single pulse from a laboratory x-ray source with a peak charging voltage of 200 kV. A resolving power of 300 was demonstrated by recording on film the Kα1 and Kα2 characteristic x-ray lines near 17 keV from a molybdenum anode. The continuum radiation from a tungsten anode was recorded in the 20-50 keV energy range. The transmission crystal spectrometer has sufficient spectral resolution and sensitivity to record the line and continuum radiation from high-Z targets irradiated by the NIF laser and the OMEGA laser.

  19. Performance of the PRAXyS X-ray Polarimeter

    CERN Document Server

    Iwakiri, W B; Cole, R; Enoto, T; Hayato, A; Hill, J E; Jahoda, K; Kaaret, P; Kitaguchi, T; Kubota, M; Marlowe, H; McCurdy, R; Takeuchi, Y; Tamagawa, T

    2016-01-01

    The performance of the Time Projection Chamber (TPC) polarimeter for the Polarimeter for Relativistic Astrophysical X-ray Sources (PRAXyS) Small Explorer was evaluated using polarized and unpolarized X-ray sources. The PRAXyS mission will enable exploration of the universe through X-ray polarimetry in the 2-10 keV energy band. We carried out performance tests of the polarimeter at the Brookhaven National Laboratory, National Synchrotron Light Source (BNL-NSLS) and at NASA's Goddard Space Flight Center. The polarimeter was tested with linearly polarized, monochromatic X-rays at 11 different energies between 2.5 and 8.0 keV. At maximum sensitivity, the measured modulation factors at 2.7, 4.5 and 8.0 keV are 27%, 43% and 59%, respectively and the measured angle of polarization is consistent with the expected value at all energies. Measurements with a broadband, unpolarized X-ray source placed a limit of less than 1% on false polarization in the PRAXyS polarimeter.

  20. X-ray follow-ups of XSS J12270-4859: a low-mass X-ray binary with gamma-ray Fermi-LAT association

    Science.gov (United States)

    de Martino, D.; Belloni, T.; Falanga, M.; Papitto, A.; Motta, S.; Pellizzoni, A.; Evangelista, Y.; Piano, G.; Masetti, N.; Bonnet-Bidaud, J.-M.; Mouchet, M.; Mukai, K.; Possenti, A.

    2013-02-01

    Context. XSS J1227.0-4859 is a peculiar, hard X-ray source recently positionally associated to the Fermi-LAT source 1FGL J1227.9-4852/2FGL J1227.7-4853. Multi-wavelength observations have added information on this source, indicating a low-luminosity low-mass X-ray binary (LMXB), but its nature is still unclear. Aims: To progress in our understanding, we present new X-ray data from a monitoring campaign performed in 2011 with the XMM-Newton, RXTE, and Swift satellites and combine them with new gamma-ray data from the Fermi and AGILE satellites. We complement the study with simultaneous near-UV photometry from XMM-Newton and with previous UV/optical and near-IR data. Methods: We analysed the temporal characteristics in the X-rays, near-UV, and gamma rays and studied the broad-band spectral energy distribution from radio to gamma rays. Results: The X-ray history of XSS J1227 over 7 yr shows a persistent and rather stable low-luminosity (6 × 1033 d1 kpc2 erg s-1) source, with flares and dips being peculiar and permanent characteristics. The associated Fermi-LAT source 2FGL J1227.7-4853 is also stable over an overlapping period of 4.7 yr. Searches for X-ray fast pulsations down to msec give upper limits to pulse fractional amplitudes of 15-25% that do not rule out a fast spinning pulsar. The combined UV/optical/near-IR spectrum reveals a hot component at ~13 kK and a cool one at ~4.6 kK. The latter would suggest a late-type K2-K5 companion star, a distance range of 1.4-3.6 kpc, and an orbital period of 7-9 h. A near-UV variability (≳6 h) also suggests a longer orbital period than previously estimated. Conclusions: The analysis shows that the X-ray and UV/optical/near-IR emissions are more compatible with an accretion-powered compact object than with a rotational powered pulsar. The X-ray to UV bolometric luminosity ratio could be consistent with a binary hosting a neutron star, but the uncertainties in the radio data may also allow an LMXB black hole with a compact

  1. X-ray hot plasma diagnostics

    International Nuclear Information System (INIS)

    X-ray plasma emission study is powerful diagnostic tool of hot plasmas. In this review article the main techniques of X-ray plasma emission measurement are shortly presented: X-ray spectrometry using absorbent filters, crystal and grating spectrometers, imaging techniques using pinhole cameras, X-ray microscopes and Fresnel zone plate cameras, X-ray plasma emission calorimetry. Advances in these techniques with examples for different hot plasma devices are also presentes. (author)

  2. The color of X-rays Spectral X-ray computed tomography using energy sensitive pixel detectors

    CERN Document Server

    Schioppa, Enrico Junior

    Energy sensitive X-ray imaging detectors are produced by connecting a semiconductor sensor to a spectroscopic pixel readout chip. In this thesis, the applicability of such detectors to X-ray Computed Tomography (CT) is studied. A prototype Medipix based silicon detector is calibrated using X-ray fluorescence. The charge transport properties of the sensor are characterized using a high energy beam of charged particles at the Super Proton Synchrotron (SPS) at the European Center for Nuclear Research (CERN). Monochromatic X-rays at the European Synchrotron Radiation Facility (ESRF) are used to determined the energy response function. These data are used to implement a physics-based CT projection operator that accounts for the transmission of the source spectrum through the sample and detector effects. Based on this projection operator, an iterative spectral CT reconstruction algorithm is developed by extending an Ordered Subset Expectation Maximization (OSEM) method. Subsequently, a maximum likelihood based algo...

  3. A Clean Sightline to Quiescence: Multiwavelength Observations of the High Galactic Latitude Black Hole X-ray Binary Swift J1357.2-0933

    CERN Document Server

    Plotkin, Richard M; Jonker, Peter G; Miller-Jones, James C A; Homan, Jeroen; Munoz-Darias, Teo; Markoff, Sera; Padilla, Montserrat Armas; Fender, Rob; Rushton, Anthony P; Russell, David M; Torres, Manuel A P

    2015-01-01

    We present coordinated multiwavelength observations of the high Galactic latitude (b=+50 deg) black hole X-ray binary (XRB) J1357.2-0933 in quiescence. Our broadband spectrum includes strictly simultaneous radio and X-ray observations, and near-infrared, optical, and ultraviolet data taken 1-2 days later. We detect Swift J1357.2-0933 at all wavebands except for the radio (f_5GHz < 3.9 uJy/beam). Given current constraints on the distance (2.3-6.3 kpc), its 0.5-10 keV X-ray flux corresponds to an Eddington ratio Lx/Ledd = 4e-9 -- 3e-8 (assuming a black hole mass of 10 Msun). The broadband spectrum is dominated by synchrotron radiation from a relativistic population of outflowing thermal electrons, which we argue to be a common signature of short-period quiescent BHXBs. Furthermore, we identify the frequency where the synchrotron radiation transitions from optically thick-to-thin (approximately 2-5e14 Hz, which is the most robust determination of a 'jet break' for a quiescent BHXB to date. Our interpretation ...

  4. X-ray emission from the A0p star IQ~Aur

    Science.gov (United States)

    Schmitt, Jurgen

    2008-10-01

    We propose to use XMM-Newton to obtain the first high-resolution X-ray spectrum of the peculiar magnetic A-type star IQ~Aur. From previous X-ray observations IQ~Aur is known as a strong, but very soft X-ray source. In addition to the HAeBe star HD~163296, IQ~Aur is a very good candidate for an A-type star with intrinsic X-ray emission. The XMM-Newton RGS spectrum will strongly constrain the location of the X-ray emission site from a measurement or upper limit to the strength of the OVII f/r line ratio, the overall RGS spectrum will determine the elemental abundances, which may be far from solar, and finally, the phase coverage of the EPIC data will be sufficient to search for a rotational modulation of IQ~Aur's X-ray flux.

  5. Achromatic X-ray lenses; Achromatische Roentgenlinsen

    Energy Technology Data Exchange (ETDEWEB)

    Umbach, Marion

    2009-07-01

    This thesis presents first results on the development of achromatic refractive X-ray lenses which can be used for scientific experiments at synchrotron sources. First of all the different requirements for achromatic X-ray lenses have been worked out. There are different types of lenses, one type can be used for monochromatized sources when the energy is scanned while the spot size should be constant. The other type can be used at beamlines providing a broad energy band. By a combination of focusing and defocusing elements we have developed a lens system that strongly reduces the chromatic aberration of a refractive lens in a given energy range. The great challenge in the X-ray case - in contrast to the visible range - the complex refractive index, which is very similar for the possible materials in the X-ray spectrum. For precise studies a numerical code has been developed, which calculates the different rays on their way through the lenses to the detector plane via raytracing. In this numerical code the intensity distribution in the detector plane has been analyzed for a chromatic and the corresponding achromatic system. By optimization routines for the two different fields of applications specific parameter combinations were found. For the experimental verification an achromatic system has been developed, consisting of biconcave SU-8 lenses and biconvex Nickel Fresnel lenses. Their fabrication was based on the LIGA-process, including a further innovative development, namely the fabrication of two different materials on one wafer. In the experiment at the synchrotron source ANKA the energy was varied in a specific energy range in steps of 0.1 keV. The intensity distribution for the different energies was detected at a certain focal length. For the achromatic system a reduction of the chromatic aberration could be clearly shown. Achromatic refractive X-ray lenses, especially for the use at synchrotron sources, have not been developed so far. As a consequence of the

  6. X-ray fluorescence spectrometry

    International Nuclear Information System (INIS)

    The seventh edition of Philips' Review of Literature on x-ray fluorescence spectrometry starts with a list of conference proceedings on the subject, organised by the Philips organisation at regular intervals in various European countries. It is followed by a list of bulletins. The bibliography is subdivided according to spectra, equipment, applications and absorption analysis

  7. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... Images related to X-ray (Radiography) - Bone About this Site RadiologyInfo.org is produced by: Please note ... you can search the ACR-accredited facilities database . This website does not provide cost information. The costs ...

  8. X-ray backscatter imaging

    Science.gov (United States)

    Dinca, Dan-Cristian; Schubert, Jeffrey R.; Callerame, J.

    2008-04-01

    In contrast to transmission X-ray imaging systems where inspected objects must pass between source and detector, Compton backscatter imaging allows both the illuminating source as well as the X-ray detector to be on the same side of the target object, enabling the inspection to occur rapidly and in a wide variety of space-constrained situations. A Compton backscatter image is similar to a photograph of the contents of a closed container, taken through the container walls, and highlights low atomic number materials such as explosives, drugs, and alcohol, which appear as especially bright objects by virtue of their scattering characteristics. Techniques for producing X-ray images based on Compton scattering will be discussed, along with examples of how these systems are used for both novel security applications and for the detection of contraband materials at ports and borders. Differences between transmission and backscatter images will also be highlighted. In addition, tradeoffs between Compton backscatter image quality and scan speed, effective penetration, and X-ray source specifications will be discussed.

  9. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos News Physician Resources Professions Site Index A-Z X-ray (Radiography) - Bone ...

  10. X-Ray Diffractive Optics

    Science.gov (United States)

    Dennis, Brian; Li, Mary; Skinner, Gerald

    2013-01-01

    X-ray optics were fabricated with the capability of imaging solar x-ray sources with better than 0.1 arcsecond angular resolution, over an order of magnitude finer than is currently possible. Such images would provide a new window into the little-understood energy release and particle acceleration regions in solar flares. They constitute one of the most promising ways to probe these regions in the solar atmosphere with the sensitivity and angular resolution needed to better understand the physical processes involved. A circular slit structure with widths as fine as 0.85 micron etched in a silicon wafer 8 microns thick forms a phase zone plate version of a Fresnel lens capable of focusing approx. =.6 keV x-rays. The focal length of the 3-cm diameter lenses is 100 microns, and the angular resolution capability is better than 0.1 arcsecond. Such phase zone plates were fabricated in Goddard fs Detector Development Lab. (DDL) and tested at the Goddard 600-microns x-ray test facility. The test data verified that the desired angular resolution and throughput efficiency were achieved.

  11. X-ray film processing

    International Nuclear Information System (INIS)

    X-ray films have to be highly sensitive, for radiation protection reasons. The films used in radiology are coated on both sides with a photosensitive emulsion. This applies to all dental films. Their properties and the development of the different exposed films are explained. (DG)

  12. X-rays and magnetism.

    Science.gov (United States)

    Fischer, Peter; Ohldag, Hendrik

    2015-09-01

    Magnetism is among the most active and attractive areas in modern solid state physics because of intriguing phenomena interesting to fundamental research and a manifold of technological applications. State-of-the-art synthesis of advanced magnetic materials, e.g. in hybrid structures paves the way to new functionalities. To characterize modern magnetic materials and the associated magnetic phenomena, polarized x-rays have emerged as unique probes due to their specific interaction with magnetic materials. A large variety of spectroscopic and microscopic techniques have been developed to quantify in an element, valence and site-sensitive way properties of ferro-, ferri-, and antiferromagnetic systems, such as spin and orbital moments, and to image nanoscale spin textures and their dynamics with sub-ns time and almost 10 nm spatial resolution. The enormous intensity of x-rays and their degree of coherence at next generation x-ray facilities will open the fsec time window to magnetic studies addressing fundamental time scales in magnetism with nanometer spatial resolution. This review will give an introduction into contemporary topics of nanoscale magnetic materials and provide an overview of analytical spectroscopy and microscopy tools based on x-ray dichroism effects. Selected examples of current research will demonstrate the potential and future directions of these techniques.

  13. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... over time. top of page What are the benefits vs. risks? Benefits Bone x-rays are the fastest and easiest ... cancer from excessive exposure to radiation. However, the benefit of an accurate diagnosis far outweighs the risk. ...

  14. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... over time. top of page What are the benefits vs. risks? Benefits Bone x-rays are the fastest and easiest ... evaluation. National and international radiology protection organizations continually review and update the technique standards used by radiology ...

  15. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... for more information about pregnancy and x-rays. A Word About Minimizing Radiation Exposure Special care is ... encourage linking to this site. × Recommend RadiologyInfo to a friend Send to (friend's e-mail address): From ( ...

  16. High-Resolution X-ray Emission and X-ray Absorption Spectroscopy

    OpenAIRE

    de Groot, F. M. F.

    2001-01-01

    In this review, high-resolution X-ray emission and X-ray absorption spectroscopy will be discussed. The focus is on the 3d transition-metal systems. To understand high-resolution X-ray emission and reso-nant X-ray emission, it is first necessary to spend some time discussing the X-ray absorption process. Section II discusses 1s X-ray absorption, i.e., the K edges, and section III deals with 2p X-ray absorption, the L edges. X-ray emission is discussed in, respectively, the L edges. X-ray emis...

  17. High-Resolution X-ray Emission and X-ray Absorption Spectroscopy

    NARCIS (Netherlands)

    Groot, F.M.F. de

    2001-01-01

    In this review, high-resolution X-ray emission and X-ray absorption spectroscopy will be discussed. The focus is on the 3d transition-metal systems. To understand high-resolution X-ray emission and reso-nant X-ray emission, it is first necessary to spend some time discussing the X-ray absorption pro

  18. Monochromatic X-ray propagation in multi-Z media for imaging and diagnostics including Kα Resonance Fluorescence

    Science.gov (United States)

    Westphal, Maximillian; Lim, Sara; Nahar, Sultana; Pradhan, Anil

    2016-05-01

    Aimed at monochromatic X-ray imaging and therapy, broadband, monochromatic, and quasi-monochromatic X-ray sources and propagation through low and high-Z (HZ) media were studied with numerically and experimentally. Monte Carlo simulations were performed using the software package Geant4, and a new code Photx, to simulate X-ray image contrast, depth of penetration, and total attenuation. The data show that monochromatic and quasi-monochromatic X-rays achieve improved contrast at lower absorbed radiation doses compared to conventional broadband 120 kV or CT scans. Experimental quasi-monochromatic high-intensity laser-produced plasma sources and monochromatic synchrotron beam data are compared. Physical processes responsible for X-ray photoexcitation and absorption are numerically modelled, including a novel mechanism for accelerating Kα resonance fluorescence via twin monochromatic X-ray beam. Potential applications are medical diagnostics and high-Z material detection. Acknowledgement: Ohio Supercomputer Center, Columbus, OH.

  19. TiO2 Nanoparticles as a Soft X-ray Molecular Probe

    Energy Technology Data Exchange (ETDEWEB)

    Larabell, Carolyn; Ashcroft, Jared M.; Gu, Weiwei; Zhang, Tierui; Hughes, Steven M.; Hartman, Keith B.; Hofmann, Cristina; Kanaras, Antonios G.; Kilcoyne, David A.; Le Gros, Mark; Yin, Yadong; Alivisatos, A. Paul; Larabell, Carolyn A.

    2007-06-30

    With the emergence of soft x-ray techniques for imaging cells, there is a pressing need to develop protein localization probes that can be unambiguously identified within the region of x-ray spectrum used for imaging. TiO2 nanocrystal colloids, which have a strong absorption cross-section within the "water-window" region of x-rays, areideally suited as soft x-ray microscopy probes. To demonstrate their efficacy, TiO2-streptavidin nanoconjugates were prepared and subsequently labeled microtubules polymerized from biotinylated tubulin. The microtubules were imaged using scanning transmission x-ray microscopy (STXM), and the TiO2 nanoparticle tags were specifically identified using x-ray absorption near edge spectroscopy (XANES). These experiments demonstrate that TiO2 nanoparticles are potential probes for protein localization analyses using soft x-ray microscopy.

  20. Prospects for X-ray observations of cosmological significance

    International Nuclear Information System (INIS)

    The cosmic X-ray background (at least in the energy band approximately 2-10 keV) shares with the microwave background the property of originating at a high redshift. Thus, studies of the structure, spectrum and origin of the X-ray background are potentially important cosmologically. Existing measurements of the background isotropy and deductions made therefrom are reviewed and seen to provide interesting limits on the matter distribution on scales larger than that of super-clusters. Source counts from the Einstein Observatory and earlier sky survey experiments show a significant (and possibly dominant) component of the X-ray background to arise from a strongly evolving population of high redshift QSO's. However, the present X-ray data do not yield definitive cosmological data, and it is concluded that the realisation of this potential must await the deep all-sky survey of ROSAT (in about 1987) and, more particularly, the 1.2 metre AXAF X-ray telescope (about 1990) with its capability to study many types of X-ray source to redshifts z >approximately 1. (Auth.)