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Sample records for x-ray spectral range

  1. The PTB high-accuracy spectral responsivity scale in the VUV and x-ray range

    NASA Astrophysics Data System (ADS)

    Gottwald, A.; Kroth, U.; Krumrey, M.; Richter, M.; Scholze, F.; Ulm, G.

    2006-04-01

    At the electron storage ring BESSY II, the Physikalisch-Technische Bundesanstalt operates ten experimental stations at six synchrotron radiation beamlines for photon metrology in the spectral range from ultraviolet radiation to x-rays. Five of these beamlines are used to realize and disseminate a scale of spectral responsivity for photodetectors. Detector calibration is based on the use of cryogenic radiometers as primary detector standards. The current status of instrumentation and measurement capabilities is described. Best measurement capabilities (k = 2) for the calibration of photodiodes vary between 0.4% and 2.3%.

  2. CO-ANALYSIS OF SOLAR MICROWAVE AND HARD X-RAY SPECTRAL EVOLUTIONS. I. IN TWO FREQUENCY OR ENERGY RANGES

    SciTech Connect

    Song Qiwu; Huang Guangli; Nakajima, Hiroshi E-mail: lhuang@pmo.ac.cn

    2011-06-20

    Solar microwave and hard X-ray spectral evolutions are co-analyzed in the 2000 June 10 and 2002 April 10 flares, and are simultaneously observed by the Owens-Valley Solar Array in the microwave band and by Yohkoh/Hard X-ray Telescope or RHESSI in the hard X-ray band, with multiple subpeaks in their light curves. The microwave and hard X-ray spectra are fitted by a power law in two frequency ranges of the optical thin part and two photon energy ranges, respectively. Similar to an earlier event in Shao and Huang, the well-known soft-hard-soft pattern of the lower energy range changed to the hard-soft-hard (HSH) pattern of the higher energy range during the spectral evolution of each subpeak in both hard X-ray flares. This energy dependence is actually supported by a positive correlation between the overall light curves and spectral evolution in the lower energy range, while it becomes an anti-correlation in the higher energy range. Regarding microwave data, the HSH pattern appears in the spectral evolution of each subpeak in the lower frequency range, which is somewhat similar to Huang and Nakajima. However, it returns back to the well-known pattern of soft-hard-harder for the overall spectral evolution in the higher frequency range of both events. This frequency dependence is confirmed by an anti-correlation between the overall light curves and spectral evolution in the lower frequency range, but it becomes a positive correlation in the higher frequency range. The possible mechanisms are discussed, respectively, for reasons why hard X-ray and microwave spectral evolutions have different patterns in different energy and frequency intervals.

  3. Response of diamond photoconductors to soft x-ray in the spectral range 125 {angstrom} to 240 {angstrom}

    SciTech Connect

    Han, S.; Wagner, R.S.; Gullikson, E.

    1995-12-01

    Due to the large bandgap of diamond, it is transparent to the visible spectrum, making it an attractive material for soft x-ray detection. Response of diamond photoconductors fabricated using Polycrystalline chemical-vapor-deposited (CVD) diamond to soft x-rays has been measured using x-rays emitted from a laser-produced plasma source in the spectral range 125 {Angstrom} to 240 {Angstrom}. These photoconductors have interdigitated electrode structure in order to increase the active area as well as detector sensitivity. Contributions to the detector sensitivity by the photoelectrons is discussed.

  4. An in-vacuum wiggler for SOLEIL Hard X-rays spectral range

    SciTech Connect

    Marcouille, O.; Chapuis, L.; Brunelle, P.; Berteaud, P.; Couprie, M.-E.; Filhol, J.-M.; Herbeaux, C.; Marlats, J.-L.; Massal, M.; Mary, A.; Tavakoli, K.; Valleau, M.; Veteran, J.

    2010-06-23

    The production of Hard X-rays has become a tricky problem on medium energy storage rings. It requires Insertion Devices (IDs) with high magnetic field and a large number of periods. To cover the 20-50 keV photon energy range at SOLEIL (2.75 GeV), an in-vacuum wiggler (WSV50) has been preferred to a superconducting ID. The wiggler is composed of 38 periods of 50 mm producing a 2.1 T field at a minimum magnetic gap of 5.5 mm. To minimize the magnetic forces acting between magnet arrays (8.5 tons), a compensation system composed of non magnetic springs has been mounted apart from the magnet system to reduce the mechanical deformations. The wiggler has been assembled step by step by means of a genetic algorithm which minimizes the magnetic errors measured with a flipping coil. This paper presents the mechanical and magnetic design of the wiggler as well as the construction and the magnetic measurements.

  5. Spectral slicing X-ray telescope

    NASA Technical Reports Server (NTRS)

    Hoover, R. B.; Shealy, D.; Chao, S.-H.

    1986-01-01

    Layered synthetic microstructure (LSM) X-ray optics is investigated as a system for coupling a conventional glancing incidence X-ray mirror to a high sensitivity X-ray detector. It is shown that, by the use of figured LSM optics, it is possible to magnify the X-ray image produced by the primary mirrors so as to maintain their high inherent spatial resolution. The results of theoretical and design analyses of several spectral slicing X-ray telescope systems that utilize LSM mirrors of hyperboloidal, spherical, ellipsoidal, and constant optical path aspheric configurations are presented. It is shown that the spherical LSM optics are the preferred configuration, yielding subarcsecond performance over the entire field. The Stanford/Marshall Space Flight Center Rocket X-ray Telescope, which will utilize normal incidence LSM optics to couple a Wolter-Schwarzschild primary mirror to high resolution detectors for solar X-ray/EUV studies, is discussed. Design diagrams are included.

  6. X-ray grating spectrometer for opacity measurements in the 50 eV to 250 eV spectral range at the LULI 2000 laser facility

    SciTech Connect

    Reverdin, Charles; Caillaud, T.; Gilleron, F.; Pain, J. C.; Silvert, V.; Soullie, G.; Villette, B.; Thais, Frederic; Loisel, Guillaume; Blenski, T.; Poirier, M.; Busquet, M.; Bastiani-Ceccotti, S.; Serres, F.; Ducret, J. E.; Foelsner, W.; Gilles, D.; Turck-Chieze, S.

    2012-10-15

    An x-ray grating spectrometer was built in order to measure opacities in the 50 eV to 250 eV spectral range with an average spectral resolution {approx} 50. It has been used at the LULI-2000 laser facility at Ecole Polytechnique (France) to measure the {Delta}n = 0, n = 3 transitions of several elements with neighboring atomic number: Cr, Fe, Ni, and Cu in the same experimental conditions. Hence a spectrometer with a wide spectral range is required. This spectrometer features one line of sight looking through a heated sample at backlighter emission. It is outfitted with one toroidal condensing mirror and several flat mirrors cutting off higher energy photons. The spectral dispersion is obtained with a flatfield grating. Detection consists of a streak camera sensitive to soft x-ray radiation. Some experimental results showing the performance of this spectrometer are presented.

  7. X-ray grating spectrometer for opacity measurements in the 50 eV to 250 eV spectral range at the LULI 2000 laser facility.

    PubMed

    Reverdin, Charles; Thais, Frdric; Loisel, Guillaume; Busquet, M; Bastiani-Ceccotti, S; Blenski, T; Caillaud, T; Ducret, J E; Foelsner, W; Gilles, D; Gilleron, F; Pain, J C; Poirier, M; Serres, F; Silvert, V; Soullie, G; Turck-Chieze, S; Villette, B

    2012-10-01

    An x-ray grating spectrometer was built in order to measure opacities in the 50 eV to 250 eV spectral range with an average spectral resolution ? 50. It has been used at the LULI-2000 laser facility at E?cole Polytechnique (France) to measure the ?n = 0, n = 3 transitions of several elements with neighboring atomic number: Cr, Fe, Ni, and Cu in the same experimental conditions. Hence a spectrometer with a wide spectral range is required. This spectrometer features one line of sight looking through a heated sample at backlighter emission. It is outfitted with one toroidal condensing mirror and several flat mirrors cutting off higher energy photons. The spectral dispersion is obtained with a flatfield grating. Detection consists of a streak camera sensitive to soft x-ray radiation. Some experimental results showing the performance of this spectrometer are presented. PMID:23126955

  8. THE SECOND STAGE OF FERMI@ELETTRA: A SEEDED FEL IN THE SOFT X-RAY SPECTRAL RANGE

    SciTech Connect

    Allaria, E.; DeNinno, G.; Fawley, W. M.

    2009-08-14

    The second stage of the FERMI FEL, named FEL-2, is based on the principle of high-gain harmonic generation and relies on a double-seeded cascade. Recent developments stimulated a revision of the original setup, which was designed to cover the spectral range between 40 and 10 nm. The numerical simulations we present here show that the nominal (expected) electron-beam performance allows extension of the FEL spectral range down to 4 nm. A significant amount of third harmonic power can be also expected. We also show that the proposed setup is flexible enough for exploiting future developments of new seed sources, e.g., high harmonic generation in gases.

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  10. Ultra-High-Spectral-Resolution X-Ray/EUV Monochromator

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.

    1991-01-01

    Ultra-high-spectral-resolution X-Ray/EUV monochromator depends on Bragg reflection from multilayer coats and diffraction by mutlilayer-coated grating to select narrow wavelength band from input beam. Its monochromatic output beam of accurately known wavelength very useful in testing and calibration of x-ray telescopes, x-ray microscopes, photographic films, and photodetectors; in research in biological and biomedical disciplines, x-ray crystallography, properties and processing of materials, and x-ray lasers; and in x-ray lithography.

  11. Soft X-ray spectral observations of quasars and high X-ray luminosity Seyfert galaxies

    NASA Technical Reports Server (NTRS)

    Petre, R.; Mushotzky, R. F.; Krolik, J. H.; Holt, S. S.

    1983-01-01

    Results of the analysis of 28 Einstein SSS observations of 15 high X-ray luminosity (L(x) 10 to the 435 power erg/s) quasars and Seyfert type 1 nuclei are presented. The 0.75-4.5 keV spectra are in general well fit by a simple model consisting of a power law plus absorption by cold gas. The averager spectral index alpha is 0.66 + or - .36, consistent with alpha for the spectrum of these objects above 2 keV. In all but one case, no evidence was found for intrinsic absorption, with an upper limit of 2 x 10 to the 21st power/sq cm. Neither was evidence found for partial covering of the active nucleus by dense, cold matter (N(H) 10 to the 22nd power/sq cm; the average upper limit on the partial covering fraction is 0.5. There is no obvious correlation between spectral index and 0175-4.5 keV X-ray luminosity (which ranges from 3 x 10 to the 43rd to 47th powers erg/s or with other source properties. The lack of intrinsic X-ray absorption allows us to place constraints on the density and temperature of the broad-line emission region, and narrow line emission region, and the intergalactic medium.

  12. Extended range X-ray telescope

    NASA Technical Reports Server (NTRS)

    Hoover, R. B. (Inventor)

    1981-01-01

    An X-ray telescope system is described which is comprised of a tubular mount having a collecting region remote from the one axial end. A soft X-ray/XUV subsystem associated with the collecting region directs only relatively soft, near on-axis X-rays/XUV radiation incident on a first portion of the collecting region into a first detector sensitive to relatively soft X-rays/XUV radiation. A hard X-ray subsystem associated with the collecting region directs only relatively hard near on-axis X-rays incident on a second portion of the collecting region into a second detector sensitive to relatively hard X-rays.

  13. Jet spectral breaks in black hole X-ray binaries

    NASA Astrophysics Data System (ADS)

    Russell, D. M.; Markoff, S.; Casella, P.; Cantrell, A. G.; Chatterjee, R.; Fender, R. P.; Gallo, E.; Gandhi, P.; Homan, J.; Maitra, D.; Miller-Jones, J. C. A.; O'Brien, K.; Shahbaz, T.

    2013-02-01

    In X-ray binaries, compact jets are known to commonly radiate at radio to infrared frequencies, whereas at optical to ?-ray energies, the contribution of the jet is debated. The total luminosity, and hence power of the jet, is critically dependent on the position of the break in its spectrum, between optically thick (self-absorbed) and optically thin synchrotron emission. This break, or turnover, has been reported in just one black hole X-ray binary (BHXB) thus far, GX 339-4, and inferred via spectral fitting in two others, A0620-00 and Cyg X-1. Here, we collect a wealth of multi-wavelength data from the outbursts of BHXBs during hard X-ray states, in order to search for jet breaks as yet unidentified in their spectral energy distributions. In particular, we report the direct detection of the jet break in the spectrum of V404 Cyg during its 1989 outburst, at ?b = (1.8 0.3) 1014 Hz (1.7 0.2 ?m). We increase the number of BHXBs with measured jet breaks from three to eight. Jet breaks are found at frequencies spanning more than two orders of magnitude, from ?b = (4.5 0.8) 1012 Hz for XTE J1118+480 during its 2005 outburst, to ?b > 4.7 1014 Hz for V4641 Sgr in outburst. A positive correlation between jet break frequency and luminosity is expected theoretically; ?b?L 0.5?, jet if other parameters are constant. With constraints on the jet break in a total of 12 BHXBs including two quiescent systems, we find a large range of jet break frequencies at similar luminosities and no obvious global relation (but such a relation cannot be ruled out for individual sources). We speculate that different magnetic field strengths and/or different radii of the acceleration zone in the inner regions of the jet are likely to be responsible for the observed scatter between sources. There is evidence that the high-energy cooling break in the jet spectrum shifts from UV energies at LX 10-8LEdd (implying the jet may dominate the X-ray emission in quiescence) to X-ray energies at 10-3LEdd. Finally, we find that the jet break luminosity scales as L?, jet?L0.56 0.05X (very similar to the radio-X-ray correlation), and radio-faint BHXBs have fainter jet breaks. In quiescence the jet break luminosity exceeds the X-ray luminosity.

  14. X-ray spectral properties of {gamma}-ray bursts

    SciTech Connect

    Strohmayer, T.E.; Fenimore, E.E.; Murakami, Toshio; Yoshida, Atsumasa

    1997-09-01

    The authors summarize the spectral characteristics of a sample of 22 bright gamma-ray bursts detected with the gamma-ray burst sensors aboard the satellite Ginga. This instrument employed a proportional and scintillation counter to provide sensitivity to photons in the 2--400 keV range, providing a unique opportunity to characterize the largely unexplored X-ray properties of gamma-ray bursts. The photon spectra of the Ginga bursts are well described by a low energy slope, a bend energy, and a high energy slope. In the energy range where they can be compared, this result is consistent with burst spectral analyses obtained from the BATSE experiment aboard the Compton Observatory. However, below 20 keV they find evidence for a positive spectral number index in approximately 40% of their burst sample, with some evidence for a strong rolloff at lower energies in a few events. They find that the distribution of spectral bend energies extends below 10 keV. The observed ratio of energy emitted in the X-rays relative to the gamma-rays can be much larger than a few percent and, in fact, is sometimes larger than unity. The average for their sample is 24%.

  15. Phase-resolved X-ray spectroscopy and spectral energy distribution of the X-ray soft polar RS Caeli

    NASA Astrophysics Data System (ADS)

    Traulsen, I.; Reinsch, K.; Schwope, A. D.; Schwarz, R.; Walter, F. M.; Burwitz, V.

    2014-02-01

    Context. RS Cae is the third target in our series of XMM-Newton observations of soft X-ray-dominated polars. Aims: Our observational campaign aims to better understand and describe the multiwavelength data, the physical properties of the system components, and the short- and long-term behavior of the component fluxes in RS Cae. Methods: We employ stellar atmosphere, stratified accretion-column, and widely used X-ray spectral models. We fit the XMM-Newton spectra, model the multiband light curves, and opt for a mostly consistent description of the spectral energy distribution. Results: Our XMM-Newton data of RS Cae are clearly dominated by soft X-ray emission. The X-ray light curves are shaped by emission from the main accretion region, which is visible over the whole orbital cycle, interrupted only by a stream eclipse. The optical light curves are formed by cyclotron and stream emission. The XMM-Newton X-ray spectra comprise a black-body-like and a plasma component at mean temperatures of 36 eV and 7 keV. The spectral fits give evidence of a partially absorbing and a reflection component. Multitemperature models, covering a broader temperature range in the X-ray emitting accretion regions, reproduce the spectra appropriately well. Including archival data, we describe the spectral energy distribution with a combination of models based on a consistent set of parameters and derive a lower limit estimate of the distance d ? 750 pc. Conclusions: The high bolometric soft-to-hard flux ratios and short-term variability of the (X-ray) light curves are characteristic of inhomogeneous accretion. RS Cae clearly belongs in the group of polars that show a very strong soft X-ray flux compared to their hard X-ray flux. The different black-body fluxes and similar hard X-ray and optical fluxes during the XMM-Newton and ROSAT observations show that soft and hard X-ray emission are not directly correlated. Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA.

  16. Spectral evolution of a long X-ray burst

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

    An X-ray burst-like event with a peak intensity 1 1/2 times that of the Crab and a decay time of approximately 100s was observed. Significant spectral changes occurred during the burst. The spectra were best fit by the black form with kT ranging from .87 keV to 2.3 keV. They suggest a source with smaller dimensions than a massive black hole. A weak source was observed after the burst with a 10 keV thermal spectrum and an indication of iron line emission.

  17. Spectral unfolds of PITHON Flash X-ray source.

    SciTech Connect

    Zarick, Thomas Andrew; Sheridan, Timothy J.; Hartman, E. Frederick; Riordan, John C.

    2007-11-01

    Using a differential absorption spectrometer we obtained experimental spectral information for the PITHON Flash X-ray Machine located in San Leandro, California at L-3 Communications. Spectral information we obtained pertained to the 200 keV to 800 keV endpoint operation of PITHON. We also obtained data on the temporal behavior of high energy and low energy spectral content.

  18. THE X-RAY SPECTRAL EVOLUTION OF GALACTIC BLACK HOLE X-RAY BINARIES TOWARD QUIESCENCE

    SciTech Connect

    Plotkin, Richard M.; Gallo, Elena; Jonker, Peter G.

    2013-08-10

    Most transient black hole X-ray binaries (BHXBs) spend the bulk of their time in a quiescent state, where they accrete matter from their companion star at highly sub-Eddington luminosities (we define quiescence here as a normalized Eddington ratio l{sub x} = L{sub 0.5-10{sub keV}}/L{sub Edd} < 10{sup -5}). Here, we present Chandra X-ray imaging spectroscopy for three BHXB systems (H 1743-322, MAXI J1659-152, and XTE J1752-223) as they fade into quiescence following an outburst. Multiple X-ray observations were taken within one month of each other, allowing us to track each individual system's X-ray spectral evolution during its decay. We compare these three systems to other BHXB systems. We confirm that quiescent BHXBs have softer X-ray spectra than low-hard-state BHXBs, and that quiescent BHXB spectral properties show no dependence on the binary system's orbital parameters. However, the observed anti-correlation between X-ray photon index ({Gamma}) and l{sub x} in the low-hard state does not continue once a BHXB enters quiescence. Instead, {Gamma} plateaus to an average ({Gamma}) = 2.08 {+-} 0.07 by the time l{sub x} reaches {approx}10{sup -5}. l{sub x} {approx} 10{sup -5} is thus an observationally motivated upper limit for the beginning of the quiescent spectral state. Our results are discussed in the context of different accretion flow models and across the black hole mass scale.

  19. X-Ray Spectral Evolution of the Crab Pulse

    NASA Technical Reports Server (NTRS)

    Harding, A. K.; Pravdo, S. H.; Angelini, L.

    1997-01-01

    The Crab Pulsar was observed with the X-ray detectors on the Rossi X-ray Timing Explorer (RXTE) on May 2, 1996. The large area, high time resolution, extended energy range, and moderate energy resolution of the RXTE instruments provided an unprecedented measurement of the Crab pulsar spectrum as it evolved in phase across the 33 msec pulse.

  20. Measurements of the absolute spectral sensitivity of X-ray semiconductor detectors in the photon energy range of 1.5-15 keV using ``white'' SR beam of the VEPP-3 storage ring

    NASA Astrophysics Data System (ADS)

    Dolbnya, I. P.; Makarov, O. A.; Mezentsev, N. A.; Pindyurin, V. F.; Subbotin, A. N.

    1995-02-01

    Results of measurements of the absolute spectral sensitivity of silicon semiconductor detectors in the X-ray quanta energy range of 1.5-15 keV are presented. The detectors, being calibrated, were placed into the direct "white" synchrotron radiation (SR) beam from the VEPP-3 storage ring. The spectrum of X-radiation at the entrance window of the detectors was changed by using sets of calibrated filters, as well as by varying the energy of the electrons in the storage ring. The possibility of accurate calculation of the SR spectrum on the calibrated detector under its irradiation in different conditions allowed us to determine the detector spectral sensitivity from a set of integral equations connecting the spectral sensitivity to the registered detector currents. The analysis of possible experimental errors indicates that the absolute spectral sensitivity of the detectors was restored with an accuracy of not worse than 10% in the total photon energy range under the study.

  1. The X-ray spectral evolution and radio-X-ray correlation in radiatively efficient black-hole sources

    NASA Astrophysics Data System (ADS)

    Dong, Ai-Jun; Wu, Qingwen; Cao, Xiao-Feng

    2016-02-01

    We explore X-ray spectral evolution and radio-X-ray correlation simultaneously for four X-ray binaries (XRBs). We find that hard X-ray photon indices, Γ, are anti- and positively correlated to X-ray fluxes when the X-ray flux, F 3-9keV, is below and above a critical flux, F X,crit, which may be regulated by ADAF and disk-corona respectively. We find that the data points with anti-correlation of Γ-F 3-9keV follow the universal radio-X-ray correlation of F R ~ F X b (b ~ 0.5-0.7), while the data points with positive X-ray spectral evolution follow a steeper radio-X-ray correlation (b ~ 1.4, the so-called `outliers track'). The bright active galactic nuclei (AGNs) share similar X-ray spectral evolution and radio-X-ray correlation as XRBs in `outliers' track, and we present a new fundamental plane of log L R=1.59+0.28 -0.22 log L X-0.22+0.19 -0.20 log M BH-28.97+0.45 -0.45 for these radiatively efficient BH sources.

  2. X-ray Spectral Measurements of the JMAR High-Power Laser-plasma Source

    NASA Astrophysics Data System (ADS)

    Whitlock, Robert R.; Dozier, Charles M.; Newman, Daniel A.; Turcu, I. C. Edmond; Gaeta, Celestino J.; Cassidy, Kelly L.; Powers, Michael F.; Kleindolph, Thomas; Morris, James H.; Forber, Richard A.

    2002-10-01

    X-ray spectra of Cu plasmas at the focus of a four-beam, solid-state diode-pumped laser have been recorded. This laser-plasma X-ray source is being developed for JMAR's lithography systems aimed at high- performance semiconductor integrated circuits. The unique simultaneous overlay of the four sub-nanosecond laser beams at 300 Hertz produces a bright, point-plasma X-ray source. PIN diode measurements of the X-ray output indicate that the conversion efficiency (ratio of X-ray emission energy into 2π steradians to incident laser energy) was approximately 9 percent with average X-ray power yields of greater than 10 Watts. Spectra were recorded on calibrated Kodak DEF film in a curved-crystal spectrograph. A KAP crystal (2d = 26.6 Angstroms) was used to disperse the 900 eV to 3000 eV spectral energies onto the film. Preliminary examination of the films indicated the existence of Cu and Cu XX ionization states. Additional spectra as a function of laser input power were also recorded to investigate potential changes in X-ray yields. These films are currently being analyzed. The analysis of the spectra provide absolute line and continuum intensities, and total X-ray output in the measured spectral range.

  3. X-ray Spectral Measurements of a Dense Plasma Focus

    NASA Astrophysics Data System (ADS)

    Whitlock, Robert R.; Dozier, Charles M.; Newman, Daniel A.; Petr, Rodney A.; Freshman, Jay; Hoey, David W.; Heaton, John

    2002-10-01

    Absolute intensities of spectra in a dense-plasma-focus (DPF) source have been recorded and analyzed. This DPF source has been identified as one of the more promising sources for X-ray lithography. The source, developed by Science Research Laboratory, Inc., is currently undergoing testing and further development at BAE Systems, Inc. The DPF operates at 60 Hz and produces an average output pulse of ~5 J of X rays into 4π steradians in a continuous operation mode. In all runs, there was an initial number of pulses, typically between 30 to 40, during which the X-ray output increased and the DPF appeared to be undergoing a conditioning process, and after which a "steady-state" mode was achieved where the average X-ray power was relatively constant. Each spectral run was exposed to ~600 J of output, as measured by the PIN. The X-ray spectral region between 0.8 and 3 keV was recorded on Kodak DEF film in a potassium acid phthalate (KAP) convex curved-crystal spectrograph. The source emits neon line radiation from Ne IX and Ne X ionization stages in the 900 to 1300 eV region, suitable for lithographic exposures of photoresist. Two helium-like neon lines contribute more than 50% of the total energy. From continuum shape, plasma temperatures were found to be approximately 170-200 eV. The absolute, integrated spectral outputs were verified to within 30% by comparison with measurements by a PIN detector and a radiachromic X-ray dosimeter.

  4. Modification of the TASMIP x-ray spectral model for the simulation of microfocus x-ray sources

    SciTech Connect

    Sisniega, A.; Vaquero, J. J.; Desco, M.; Instituto de Investigación Sanitaria Gregorio Marañón, Madrid ES28007; Centro de Investigación Biomédica en Red de Salud Mental , Madrid ES28029

    2014-01-15

    Purpose: The availability of accurate and simple models for the estimation of x-ray spectra is of great importance for system simulation, optimization, or inclusion of photon energy information into data processing. There is a variety of publicly available tools for estimation of x-ray spectra in radiology and mammography. However, most of these models cannot be used directly for modeling microfocus x-ray sources due to differences in inherent filtration, energy range and/or anode material. For this reason the authors propose in this work a new model for the simulation of microfocus spectra based on existing models for mammography and radiology, modified to compensate for the effects of inherent filtration and energy range. Methods: The authors used the radiology and mammography versions of an existing empirical model [tungsten anode spectral model interpolating polynomials (TASMIP)] as the basis of the microfocus model. First, the authors estimated the inherent filtration included in the radiology model by comparing the shape of the spectra with spectra from the mammography model. Afterwards, the authors built a unified spectra dataset by combining both models and, finally, they estimated the parameters of the new version of TASMIP for microfocus sources by calibrating against experimental exposure data from a microfocus x-ray source. The model was validated by comparing estimated and experimental exposure and attenuation data for different attenuating materials and x-ray beam peak energy values, using two different x-ray tubes. Results: Inherent filtration for the radiology spectra from TASMIP was found to be equivalent to 1.68 mm Al, as compared to spectra obtained from the mammography model. To match the experimentally measured exposure data the combined dataset required to apply a negative filtration of about 0.21 mm Al and an anode roughness of 0.003 mm W. The validation of the model against real acquired data showed errors in exposure and attenuation in line with those reported for other models for radiology or mammography. Conclusions: A new version of the TASMIP model for the estimation of x-ray spectra in microfocus x-ray sources has been developed and validated experimentally. Similarly to other versions of TASMIP, the estimation of spectra is very simple, involving only the evaluation of polynomial expressions.

  5. Modification of the TASMIP x-ray spectral model for the simulation of microfocus x-ray sources

    SciTech Connect

    Sisniega, A.; Vaquero, J. J.; Desco, M.; Instituto de Investigacin Sanitaria Gregorio Maran, Madrid ES28007; Centro de Investigacin Biomdica en Red de Salud Mental , Madrid ES28029

    2014-01-15

    Purpose: The availability of accurate and simple models for the estimation of x-ray spectra is of great importance for system simulation, optimization, or inclusion of photon energy information into data processing. There is a variety of publicly available tools for estimation of x-ray spectra in radiology and mammography. However, most of these models cannot be used directly for modeling microfocus x-ray sources due to differences in inherent filtration, energy range and/or anode material. For this reason the authors propose in this work a new model for the simulation of microfocus spectra based on existing models for mammography and radiology, modified to compensate for the effects of inherent filtration and energy range. Methods: The authors used the radiology and mammography versions of an existing empirical model [tungsten anode spectral model interpolating polynomials (TASMIP)] as the basis of the microfocus model. First, the authors estimated the inherent filtration included in the radiology model by comparing the shape of the spectra with spectra from the mammography model. Afterwards, the authors built a unified spectra dataset by combining both models and, finally, they estimated the parameters of the new version of TASMIP for microfocus sources by calibrating against experimental exposure data from a microfocus x-ray source. The model was validated by comparing estimated and experimental exposure and attenuation data for different attenuating materials and x-ray beam peak energy values, using two different x-ray tubes. Results: Inherent filtration for the radiology spectra from TASMIP was found to be equivalent to 1.68mm Al, as compared to spectra obtained from the mammography model. To match the experimentally measured exposure data the combined dataset required to apply a negative filtration of about 0.21 mm Al and an anode roughness of 0.003 mm W. The validation of the model against real acquired data showed errors in exposure and attenuation in line with those reported for other models for radiology or mammography. Conclusions: A new version of the TASMIP model for the estimation of x-ray spectra in microfocus x-ray sources has been developed and validated experimentally. Similarly to other versions of TASMIP, the estimation of spectra is very simple, involving only the evaluation of polynomial expressions.

  6. X-ray spectral signatures of photoionized plasmas. [astrophysics

    NASA Technical Reports Server (NTRS)

    Liedahl, Duane A.; Kahn, Steven M.; Osterheld, Albert L.; Goldstein, William H.

    1990-01-01

    Plasma emission codes have become a standard tool for the analysis of spectroscopic data from cosmic X-ray sources. However, the assumption of collisional equilibrium, typically invoked in these codes, renders them inapplicable to many important astrophysical situations, particularly those involving X-ray photoionized nebulae. This point is illustrated by comparing model spectra which have been calculated under conditions appropriate to both coronal plasmas and X-ray photoionized plasmas. It is shown that the (3s-2p)/(3d-2p) line ratios in the Fe L-shell spectrum can be used to effectively discriminate between these two cases. This diagnostic will be especially useful for data analysis associated with AXAF and XMM, which will carry spectroscopic instrumentation with sufficient sensitivity and resolution to identify X-ray photoionized nebulae in a wide range of astrophysical environments.

  7. Single-step absorption and phase retrieval with polychromatic x-rays using a spectral detector

    PubMed Central

    Gürsoy, Doğga; Das, Mini

    2013-01-01

    In this letter we present a single-step method to simultaneously retrieve x-ray absorption and phase images valid for a broad range of imaging energies and material properties. Our method relies on the availability of spectrally resolved intensity measurements, which is now possible using semiconductor x-ray photon counting detectors. The new retrieval method is derived and presented with results showing good agreement. PMID:23632518

  8. Spectral Properties of X-ray-Emitting Quasars

    NASA Astrophysics Data System (ADS)

    Morgan, W. A., Jr.

    1996-12-01

    I present spectral indices obtained from 112 X-ray-selected and fully optically-identified quasars in four sky fields in the southern hemisphere, detected by the Rosat Position Sensitive Proportional Counters. These fields were originally studied by Boyle et al. (1990) for the ultraviolet-excess properties of objects in the fields; only 47 of the quasars in the field were listed in Boyle et al. I determine the quasars' power-law spectral index alpha_E with three different methods: spectral ``stacking'', hardness ratios, and direct fitting. Both spectral stacking and the hardness ratio methods are used because several of the quasars were too dim to reliably calculate spectral indices individually. The spectral stacking method, which involves co-adding quasar spectra energy bins, shows a definite change in quasar spectral index with redshift.

  9. Magnetic circular dichroism in the hard X-ray range

    NASA Astrophysics Data System (ADS)

    Rogalev, A.; Wilhelm, F.

    2015-12-01

    An overview of X-ray magnetic circular dichroism (XMCD) spectroscopy in the hard X-ray range is presented. A short historical overview shows how this technique has evolved from the early days of X-ray physics to become a workhorse technique in the modern magnetism research As with all X-ray spectroscopies, XMCD has the advantage of being element specific. Interpretation of the spectra based on magneto-optical sum rules can provide unique information about spin and orbital moment carried by absorbing atom in both amplitude and direction, can infer magnetic interactions from element selective magnetization curves, can allow separation of magnetic and non-magnetic components in heterogeneous systems. The review details the technology currently available for XMCD measurements in the hard X-ray range referring to the ESRF beamline ID12 as an example. The strengths of hard X-ray magnetic circular dichroism technique are illustrated with a wide variety of representative examples, such as actinide based ferromagnets, paramagnetism in metals, pure metallic nanoparticles, exchange spring magnets, half metallic ferromagnets, magnetism at interfaces, and dilute magnetic semiconductors. In this way, we aim to encourage researchers from various scientific communities to consider XMCD as a tool to understanding the electronic and magnetic properties of their samples.

  10. Advances toward high spectral resolution quantum X-ray calorimetry

    NASA Technical Reports Server (NTRS)

    Moseley, S. H.; Kelley, R. L.; Schoelkopf, R. J.; Szymkowiak, A. E.; Mccammon, D.

    1988-01-01

    Thermal detectors for X-ray spectroscopy combining high spectral resolution and quantum efficiency have been developed. These microcalorimeters measure the energy released in the absorption of a single photon by sensing the rise in temperature of a small absorbing structure. The ultimate energy resolution of such a device is limited by the thermodynamic power fluctuations in the thermal link between the calorimeter and isothermal bath and can in principle be made as low as 1 eV. The performance of a real device is degraded due to noise contributions such as excess 1/f noise in the thermistor and incomplete conversion of energy into phonons. The authors report some recent advances in thermometry, X-ray absorption and thermalization, fabrication techniques, and detector optimization in the presence of noise. These improvements have resulted in a device with a spectral resolution of 17 eV FWHM, measured at 6 keV.

  11. Different X-ray spectral evolution for black hole X-ray binaries in dual tracks of radio-X-ray correlation

    SciTech Connect

    Cao, Xiao-Feng; Wu, Qingwen; Dong, Ai-Jun

    2014-06-10

    Recently, an 'outlier' track of radio-X-ray correlation was found, which is much steeper than the former universal correlation, where dual tracks were speculated to be triggered by different accretion processes. In this work, we test this issue by exploring hard X-ray spectral evolution in four black-hole X-ray binaries with multiple, quasi-simultaneous radio and X-ray observations. First, we find that hard X-ray photon indices, Γ, are negatively and positively correlated with X-ray fluxes when the X-ray flux, F{sub 3-9} {sub keV}, is below and above a critical flux, F{sub X,} {sub crit}, which are consistent with predictions of the advection-dominated accretion flow and the disk-corona model, respectively. Second, and most importantly, we find that the radio-X-ray correlations are also clearly different when the X-ray fluxes are higher and lower than the critical flux as defined by X-ray spectral evolution. The data points with F{sub 3-9} {sub keV} ≳ F{sub X,} {sub crit} have a steeper radio-X-ray correlation (F{sub X}∝F{sub R}{sup b} and b ∼ 1.1-1.4), which roughly forms the ''outlier'' track. However, the data points with anti-correlation of Γ – F{sub 3-9} {sub keV} either stay in the universal track with b ∼ 0.61 or stay in the transition track (from the universal to 'outlier' tracks or vice versa). Therefore, our results support that the universal and ''outlier'' tracks of radio-X-ray correlations are regulated by radiatively inefficient and radiatively efficient accretion model, respectively.

  12. XSPEC: An X-ray spectral fitting package

    NASA Astrophysics Data System (ADS)

    Arnaud, Keith; Dorman, Ben; Gordon, Craig

    1999-10-01

    It has been over a decade since the first paper was published containing results determined using the general X-ray spectral-fitting program XSPEC. Since then XSPEC has become the most widely used program for this purpose, being the de facto standard for the ROSAT and the de jure standard for the ASCA and XTE satellites. Probably the most important features of XSPEC are the large number of theoretical models available and the facilities for adding new models.

  13. BROADBAND SPECTRAL ANALYSIS OF THE GALACTIC RIDGE X-RAY EMISSION

    SciTech Connect

    Yuasa, Takayuki; Makishima, Kazuo; Nakazawa, Kazuhiro

    2012-07-10

    Detailed spectral analysis of the Galactic X-ray background emission, or the Galactic Ridge X-ray Emission (GRXE), is presented. To study the origin of the emission, broadband and high-quality GRXE spectra were produced from 18 pointing observations with Suzaku in the Galactic bulge region, with a total exposure of 1 Ms. The spectra were successfully fitted by a sum of two major spectral components: a spectral model of magnetic accreting white dwarfs with a mass of 0.66{sup +0.09}{sub -0.07} M{sub Sun} and a softer optically thin thermal emission with a plasma temperature of 1.2-1.5 keV that is attributable to coronal X-ray sources. When combined with previous studies that employed high spatial resolution of the Chandra satellite, the present spectroscopic result gives stronger support to the scenario that the GRXE is essentially an assembly of numerous discrete faint X-ray stars. The detected GRXE flux in the hard X-ray band was used to estimate the number density of the unresolved hard X-ray sources. When integrated over a luminosity range of {approx}10{sup 30}-10{sup 34} erg s{sup -1}, the result is consistent with a value that was reported previously by directly resolving faint point sources.

  14. White dwarf mass estimation with a new comprehensive X-ray spectral model of intermediate polars

    NASA Astrophysics Data System (ADS)

    Hayashi, Takayuki; Ishida, Manabu

    A white dwarf (WD) mass is important astrophysical quantity because the WD explodes as a type Ia supernova when its mass reaches the Chandrasekhar mass limit of 1.4 solar mass. Many WD masses in intermediate polars (IPs) were measured with their X-ray spectra emitted from plasma flows channeled by strong magnetic fields of the WDs. For the WD mass estimation, multi-temperature X-ray spectral models have been used which made by summing up X-ray spectra emitted from the top to the bottom of the plasma flow. However, in previous studies, distributions of physical quantities such as temperature and density etc., which are base of the X-ray spectral model, were calculated with assumptions of accretion rate per unit area (call "specific accretion rate") a = 1 g cm(-2) s(-1) and cylindrical geometry for the plasma flows. In fact, a part of the WD masses estimated with the X-ray spectral model is not consistent with that dynamically measured. Therefore, we calculated the physical quantity distributions with the dipolar geometry and the wide range of the specific accretion rate a = 0.0001 - 100 g cm(-2) s(-1) . The calculations showed that the geometrical difference changes the physical quantity distributions and the lower specific accretion rate leads softer X-ray spectrum under a critical specific accretion rate. These results clearly indicate that the previous assumptions are not good approximation for low accretion IPs. We made a new spectral model of the plasma flow with our physical quantity distributions and applied that to Suzaku observations of high and low accretion rate IPs V1223 Sagittarii and EX Hydrae. As a results, our WD masses are almost consistent with the those dynamically measured. We will present the summary of our theoretical calculation and X-ray spectral model, and application to the {it Suzaku} observations.

  15. SPECTRAL STATES AND EVOLUTION OF ULTRALUMINOUS X-RAY SOURCES

    SciTech Connect

    Feng Hua; Kaaret, Philip

    2009-05-10

    We examined spectral evolution in ultraluminous X-ray sources (ULXs) with apparent luminosities of about 10{sup 40} erg s{sup -1}. Based on new results in this paper, and those reported in the literature, two common spectral behaviors were found. Some ULXs in starburst galaxies have varying luminosity (L) but remain in the hard state with power-law spectra and a constant, hard photon index ({gamma}). Other ULXs, such as NGC 5204 X-1, show a correlation between L and {gamma}. We interpret this L-{gamma} correlated phase as an intermediate state with hybrid properties from the thermal dominant and steep power-law states. When the spectra of NGC 5204 X-1 are fitted with a multicolor disk blackbody plus power-law model, the X-ray luminosity increases with the effective temperature of the accretion disk in a manner similar to that found in stellar-mass black hole X-ray binaries, suggesting that the emission arises from an accretion disk. The luminosity, disk size, and temperature suggest that NGC 5204 X-1 harbors a compact object more massive than stellar-mass black holes. In contrast, the disk model in IC 342 X-1 is ruled out because the luminosity decreases as the temperature increases; sources with such behavior may represent a class of objects with super-Eddington accretion. Also, we report a peculiar soft spectral feature from IC 342 X-2 and variability on a timescale of 20 ks from Holmberg II X-1. More observations are needed to test these results.

  16. Spectral slicing X-ray telescope with variable magnification

    NASA Technical Reports Server (NTRS)

    Hoover, R. B.; Hildner, E. (inventors)

    1985-01-01

    A telescope for viewing high frequency radiation (soft X-ray, extreme ultraviolet) is described. This telescope has a long focal length with a selection of magnifications despite a short housing. Light enters the telescope and is reflected by the telescope's primary optical system to one of several secondary mirrors at different locations on a movable frame. The secondary mirrors have varying degrees of magnification and select narrow spectral slices of the incident radiation. Thus, both the magnification and effective focal length field of view and wavelength can be altered by repositioning the moving frame. Configurations for spaceborne applications are discussed.

  17. SPECTRAL PROPERTIES OF X-RAY BINARIES IN CENTAURUS A

    SciTech Connect

    Burke, Mark J.; Raychaudhury, Somak; Kraft, Ralph P.; Forman, William R.; Jones, Christine; Murray, Stephen S.; Birkinshaw, Mark; Evans, Daniel A.; Jordan, Andres; Maccarone, Thomas J.; Croston, Judith H.; Brassington, Nicola J.; Hardcastle, Martin J.; Goodger, Joanna L.; Kainulainen, Jouni; Woodley, Kristin A.; Sivakoff, Gregory R.; Gilfanov, Marat; Sarazin, Craig L.; Voss, Rasmus [Department of Astrophysics and others

    2013-04-01

    We present a spectral investigation of X-ray binaries (XBs) in NGC 5128 (Cen A), using six 100 ks Chandra observations taken over two months in 2007. We divide our sample into thermally and non-thermally dominated states based on the behavior of the fitted absorption column N{sub H}, and present the spectral parameters of sources with L{sub x} {approx}> 2 Multiplication-Sign 10{sup 37} erg s{sup -1}. The majority of sources are consistent with being neutron star low-mass X-ray binaries (NS LMXBs) and we identify three transient black hole (BH) LMXB candidates coincident with the dust lane, which is the remnant of a small late-type galaxy. Our results also provide tentative support for the apparent 'gap' in the mass distribution of compact objects between {approx}2-5 M{sub Sun }. We propose that BH LMXBs are preferentially found in the dust lane, and suggest this is because of the younger stellar population. The majority ({approx}70%-80%) of potential Roche lobe filling donors in the Cen A halo are {approx}> 12 Gyr old, while BH LMXBs require donors {approx}> 1 M{sub Sun} to produce the observed peak luminosities. This requirement for more massive donors may also explain recent results that claim a steepening of the X-ray luminosity function with age at L{sub x} {>=} 5 Multiplication-Sign 10{sup 38} erg s{sup -1} for the XB population of early-type galaxies; for older stellar populations, there are fewer stars {approx}> 1 M{sub Sun }, which are required to form the more luminous sources.

  18. Energy calibration of the pixels of spectral X-ray detectors.

    PubMed

    Panta, Raj Kumar; Walsh, Michael F; Bell, Stephen T; Anderson, Nigel G; Butler, Anthony P; Butler, Philip H

    2015-03-01

    The energy information acquired using spectral X-ray detectors allows noninvasive identification and characterization of chemical components of a material. To achieve this, it is important that the energy response of the detector is calibrated. The established techniques for energy calibration are not practical for routine use in pre-clinical or clinical research environment. This is due to the requirements of using monochromatic radiation sources such as synchrotron, radio-isotopes, and prohibitively long time needed to set up the equipment and make measurements. To address these limitations, we have developed an automated technique for calibrating the energy response of the pixels in a spectral X-ray detector that runs with minimal user intervention. This technique uses the X-ray tube voltage (kVp) as a reference energy, which is stepped through an energy range of interest. This technique locates the energy threshold where a pixel transitions from not-counting (off) to counting (on). Similarly, we have developed a technique for calibrating the energy response of individual pixels using X-ray fluorescence generated by metallic targets directly irradiated with polychromatic X-rays, and additionally ?-rays from (241)Am. This technique was used to measure the energy response of individual pixels in CdTe-Medipix3RX by characterizing noise performance, threshold dispersion, gain variation and spectral resolution. The comparison of these two techniques shows the energy difference of 1 keV at 59.5 keV which is less than the spectral resolution of the detector (full-width at half-maximum of 8 keV at 59.5 keV). Both techniques can be used as quality control tools in a pre-clinical multi-energy CT scanner using spectral X-ray detectors. PMID:25051546

  19. Investigation of pulsed X-ray radiation of a plasma focus in a broad energy range

    SciTech Connect

    Savelov, A. S. Salakhutdinov, G. Kh.; Koltunov, M. V.; Lemeshko, B. D.; Yurkov, D. I.; Sidorov, P. P.

    2011-12-15

    The results of the experimental investigations of the spectral composition of plasma focus X-ray radiation in the photon energy range of 1.5 keV-400 keV are presented. Three regions in the radiation spectrum where the latter is of a quasi-thermal nature with a corresponding effective temperature are distinguished.

  20. The Extended Range X-Ray Telescope center director's discretionary fund report

    NASA Technical Reports Server (NTRS)

    Hoover, R. B.; Cumings, N. P.; Hildner, E.; Moore, R. L.; Tandberg-Hanssen, E. A.

    1985-01-01

    An Extended Range X-Ray Telescope (ERXRT) of high sensitivity and spatial resolution capable of functioning over a broad region of the X-ray/XUV portion of the spectrum has been designed and analyzed. This system has been configured around the glancing-incidence Wolter Type I X-ray mirror system which was flown on the Skylab Apollo Telescope Mount as ATM Experiment S-056. Enhanced sensitivity over a vastly broader spectral range can be realized by the utilization of a thinned, back-illuminated, buried-channel Charge Coupled Device (CCD) as the X-ray/XUV detector rather than photographic film. However, to maintain the high spatial resolution inherent in the X-ray optics when a CCD of 30 micron pixel size is used, it is necessary to increase the telescope plate scale. This can be accomplished by use of a glancing-incidence X-ray microscope to enlarge and re-focus the primary image onto the focal surface of the CCD.

  1. X-ray spectral states of black holes binaries

    NASA Astrophysics Data System (ADS)

    Malzac, Julien

    I present INTEGRAL observations of the prototypical sources Cygnus X-1 and GX 339-4 in various X-ray spectral states (including during the TeV detection of Cygnus X-1 by MAGIC). Detailed spectral analysis of the evolution of these sources during state transitions allows us to follow the spectral evolution from the Low Hard State (LHS: dominated by thermal comptonisation) to the High Soft State (HSS: dominated by the accretion disc thermal emission and non-thermal comptonisation in the corona). Across the transition, the accretion disc luminosity increases by at least one order of magnitude while the comptonised coronal luminosity does not changes dramatically. We also attempt to model the observed spectra using a new Fokker-Planck code accounting for the so-called 'synchrotron boiler effect'. These numerical simulations indicate that in both spectral states the magnetised corona could be powered essentially through acceleration of non-thermal particles. The main differences between the LHS and HSS coronal emission can then be understood as the consequence of the strong cooling soft photon flux from the disc present in the HSS and absent in the LHS. This suggests that, contrary to current beliefs, the corona of the HSS and that of the LHS could be of very similar nature.

  2. X-ray spectral states of accreting black holes binaries

    NASA Astrophysics Data System (ADS)

    Malzac, Julien

    I present INTEGRAL observations of the prototypical sources Cygnus X-1 and GX 339-4 in various X-ray spectral states (including during the TeV detection of Cygnus X-1 by MAGIC). Detailed spectral analysis of the evolution of these sources during state transitions allows us to follow the spectral evolution from the Low Hard State (LHS: dominated by thermal comptonisation) to the High Soft State (HSS: dominated by the accretion disc thermal emission and non-thermal comptonisation in the corona). Across the transition, the accretion disc luminosity increases by at least one order of magnitude while the comptonised coronal luminosity does not changes dramatically. We also attempt to model the observed spectra using a new Fokker-Planck code accounting for the so-called 'synchrotron boiler effect'. These numerical simulations indicate that in both spectral states the magnetised corona could be powered essentially through acceleration of non-thermal particles. The main differences between the LHS and HSS coronal emission can then be understood as the consequence of the strong cooling soft photon flux from the disc present in the HSS and absent in the LHS. This suggests that, contrary to current beliefs, the corona of the HSS and that of the LHS could be of very similar nature.

  3. X-ray signatures: New time scales and spectral features

    NASA Technical Reports Server (NTRS)

    Boldt, E. A.

    1977-01-01

    The millisecond bursts from Cyg X-1 are investigated and the overall chaotic variability for the bulk of the Cyg X-1 emission is compared to that of Sco X-1, showing that the essential character is remarkably similar (i.e. shot noise) although the fundamental time scales involved differ widely, from a fraction of a second (for Cyg X-1) to a fraction of a day (for Sco X-1). Recent OSO-8 observations of spectra features attributable to iron are reviewed. In particular, line emission is discussed within the context of a model for thermal radiation by a hot evolved gas in systems as different as supernova remnants and clusters of galaxies. Newly observed spectral structure in the emission from the X-ray pulsar Her X-1 is reported.

  4. A novel x-ray circularly polarized ranging method

    NASA Astrophysics Data System (ADS)

    Song, Shi-Bin; Xu, Lu-Ping; Zhang, Hua; Gao, Na; Shen, Yang-He

    2015-05-01

    Range measurement has found multiple applications in deep space missions. With more and further deep space exploration activities happening now and in the future, the requirement for range measurement has risen. In view of the future ranging requirement, a novel x-ray polarized ranging method based on the circular polarization modulation is proposed, termed as x-ray circularly polarized ranging (XCPolR). XCPolR utilizes the circular polarization modulation to process x-ray signals and the ranging information is conveyed by the circular polarization states. As the circular polarization states present good stability in space propagation and x-ray detectors have light weight and low power consumption, XCPolR shows great potential in the long-distance range measurement and provides an option for future deep space ranging. In this paper, we present a detailed illustration of XCPolR. Firstly, the structure of the polarized ranging system is described and the signal models in the ranging process are established mathematically. Then, the main factors that affect the ranging accuracy, including the Doppler effect, the differential demodulation, and the correlation error, are analyzed theoretically. Finally, numerical simulation is carried out to evaluate the performance of XCPolR. Projects supported by the National Natural Science Foundation of China (Grant Nos. 61172138 and 61401340), the Natural Science Basic Research Plan in Shaanxi Province of China (Grant No. 2013JQ8040), the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20130203120004), the Open Research Fund of the Academy of Satellite Application, China (Grant No. 2014 CXJJ-DH 12), the Xian Science and Technology Plan, China (Grant No. CXY1350(4)), the Fundamental Research Funds for the Central Universities, China (Grant Nos. 201413B, 201412B, and JB141303), and the Open Fund of Key Laboratory of Precision Navigation and Timing Technology, National Time Service Center, Chinese Academy of Sciences (Grant Nos. 2014PNTT01, 2014PNTT07, and 2014PNTT08).

  5. X-ray spectral variability of Seyfert 2 galaxies

    NASA Astrophysics Data System (ADS)

    Hernández-García, L.; Masegosa, J.; González-Martín, O.; Márquez, I.

    2015-07-01

    Context. Variability across the electromagnetic spectrum is a property of active galactic nuclei (AGN) that can help constrain the physical properties of these galaxies. Nonetheless, the way in which the changes happen and whether they occur in the same way in every AGN are still open questions. Aims: This is the third in a series of papers with the aim of studying the X-ray variability of different families of AGN. The main purpose of this work is to investigate the variability pattern(s) in a sample of optically selected Seyfert 2 galaxies. Methods: We use the 26 Seyfert 2s in the Véron-Cetty and Véron catalog with data available from Chandra and/or XMM-Newton public archives at different epochs, with timescales ranging from a few hours to years. All the spectra of the same source were simultaneously fitted, and we let different parameters vary in the model. Whenever possible, short-term variations from the analysis of the light curves and/or long-term UV flux variations were studied. We divided the sample into Compton-thick and Compton-thin candidates to account for the degree of obscuration. When transitions between Compton-thick and thin were obtained for different observations of the same source, we classified it as a changing-look candidate. Results: Short-term variability at X-rays was studied in ten cases, but variations are not found. From the 25 analyzed sources, 11 show long-term variations. Eight (out of 11) are Compton-thin, one (out of 12) is Compton-thick, and the two changing-look candidates are also variable. The main driver for the X-ray changes is related to the nuclear power (nine cases), while variations at soft energies or related to absorbers at hard X-rays are less common, and in many cases these variations are accompanied by variations in the nuclear continuum. At UV frequencies, only NGC 5194 (out of six sources) is variable, but the changes are not related to the nucleus. We report two changing-look candidates, MARK 273 and NGC 7319. Conclusions: A constant reflection component located far away from the nucleus plus a variable nuclear continuum are able to explain most of our results. Within this scenario, the Compton-thick candidates are dominated by reflection, which suppresses their continuum, making them seem fainter, and they do not show variations (except MARK 3), while the Compton-thin and changing-look candidates do. Appendices are available in electronic form at http://www.aanda.org

  6. Spectral reconstruction of dental X-ray tubes using laplace inverse transform of the attenuation curve

    NASA Astrophysics Data System (ADS)

    Malezan, A.; Tomal, A.; Antoniassi, M.; Watanabe, P. C. A.; Albino, L. D.; Poletti, M. E.

    2015-11-01

    In this work, a spectral reconstruction methodology for diagnostic X-ray, using Laplace inverse transform of the attenuation, was successfully applied to dental X-ray equipments. The attenuation curves of 8 commercially available dental X-ray equipment, from 3 different manufactures (Siemens, Gnatus and Dabi Atlante), were obtained by using an ionization chamber and high purity aluminium filters, while the kVp was obtained with a specific meter. A computational routine was implemented in order to adjust a model function, whose inverse Laplace transform is analytically known, to the attenuation curve. This methodology was validated by comparing the reconstructed and the measured (using semiconductor detector of cadmium telluride) spectra of a given dental X-ray unit. The spectral reconstruction showed the Dabi Atlante equipments generating similar shape spectra. This is a desirable feature from clinic standpoint because it produces similar levels of image quality and dose. We observed that equipments from Siemens and Gnatus generate significantly different spectra, suggesting that, for a given operating protocol, these units will present different levels of image quality and dose. This fact claims for the necessity of individualized operating protocols that maximize image quality and dose. The proposed methodology is suitable to perform a spectral reconstruction of dental X-ray equipments from the simple measurements of attenuation curve and kVp. The simplified experimental apparatus and the low level of technical difficulty make this methodology accessible to a broad range of users. The knowledge of the spectral distribution can help in the development of operating protocols that maximize image quality and dose.

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

    NASA Astrophysics Data System (ADS)

    Vishnyakov, E. A.; Shatokhin, A. N.; Ragozin, E. N.

    2015-04-01

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

  8. Measurement of breast-tissue x-ray attenuation by spectral mammography: solid lesions.

    PubMed

    Fredenberg, Erik; Kilburn-Toppin, Fleur; Willsher, Paula; Moa, Elin; Danielsson, Mats; Dance, David R; Young, Kenneth C; Wallis, Matthew G

    2016-04-01

    Knowledge of x-ray attenuation is essential for developing and evaluating x-ray imaging technologies. For instance, techniques to distinguish between cysts and solid tumours at mammography screening would be highly desirable to reduce recalls, but the development requires knowledge of the x-ray attenuation for cysts and tumours. We have previously measured the attenuation of cyst fluid using photon-counting spectral mammography. Data on x-ray attenuation for solid breast lesions are available in the literature, but cover a relatively wide range, likely caused by natural spread between samples, random measurement errors, and different experimental conditions. In this study, we have adapted a previously developed spectral method to measure the linear attenuation of solid breast lesions. A total of 56 malignant and 5 benign lesions were included in the study. The samples were placed in a holder that allowed for thickness measurement. Spectral (energy-resolved) images of the samples were acquired and the image signal was mapped to equivalent thicknesses of two known reference materials, which can be used to derive the x-ray attenuation as a function of energy. The spread in equivalent material thicknesses was relatively large between samples, which is likely to be caused mainly by natural variation and only to a minor extent by random measurement errors and sample inhomogeneity. No significant difference in attenuation was found between benign and malignant solid lesions. The separation between cyst-fluid and tumour attenuation was, however, significant, which suggests it may be possible to distinguish cystic from solid breast lesions, and the results lay the groundwork for a clinical trial. In addition, the study adds a relatively large sample set to the published data and may contribute to a reduction in the overall uncertainty in the literature. PMID:26961507

  9. Measurement of breast-tissue x-ray attenuation by spectral mammography: solid lesions

    NASA Astrophysics Data System (ADS)

    Fredenberg, Erik; Kilburn-Toppin, Fleur; Willsher, Paula; Moa, Elin; Danielsson, Mats; Dance, David R.; Young, Kenneth C.; Wallis, Matthew G.

    2016-04-01

    Knowledge of x-ray attenuation is essential for developing and evaluating x-ray imaging technologies. For instance, techniques to distinguish between cysts and solid tumours at mammography screening would be highly desirable to reduce recalls, but the development requires knowledge of the x-ray attenuation for cysts and tumours. We have previously measured the attenuation of cyst fluid using photon-counting spectral mammography. Data on x-ray attenuation for solid breast lesions are available in the literature, but cover a relatively wide range, likely caused by natural spread between samples, random measurement errors, and different experimental conditions. In this study, we have adapted a previously developed spectral method to measure the linear attenuation of solid breast lesions. A total of 56 malignant and 5 benign lesions were included in the study. The samples were placed in a holder that allowed for thickness measurement. Spectral (energy-resolved) images of the samples were acquired and the image signal was mapped to equivalent thicknesses of two known reference materials, which can be used to derive the x-ray attenuation as a function of energy. The spread in equivalent material thicknesses was relatively large between samples, which is likely to be caused mainly by natural variation and only to a minor extent by random measurement errors and sample inhomogeneity. No significant difference in attenuation was found between benign and malignant solid lesions. The separation between cyst-fluid and tumour attenuation was, however, significant, which suggests it may be possible to distinguish cystic from solid breast lesions, and the results lay the groundwork for a clinical trial. In addition, the study adds a relatively large sample set to the published data and may contribute to a reduction in the overall uncertainty in the literature.

  10. Broadband high resolution X-ray spectral analyzer

    DOEpatents

    Silver, E.H.; Legros, M.; Madden, N.W.; Goulding, F.; Landis, D.

    1998-07-07

    A broad bandwidth high resolution X-ray fluorescence spectrometer has a performance that is superior in many ways to those currently available. It consists of an array of 4 large area microcalorimeters with 95% quantum efficiency at 6 keV and it produces X-ray spectra between 0.2 keV and 7 keV with an energy resolution of 7 to 10 eV. The resolution is obtained at input count rates per array element of 10 to 50 Hz in real-time, with analog pulse processing and thermal pile-up rejection. This performance cannot be matched by currently available X-ray spectrometers. The detectors are incorporated into a compact and portable cryogenic refrigerator system that is ready for use in many analytical spectroscopy applications as a tool for X-ray microanalysis or in research applications such as laboratory and astrophysical X-ray and particle spectroscopy. 6 figs.

  11. Broadband high resolution X-ray spectral analyzer

    DOEpatents

    Silver, Eric H. (Berkeley, CA); Legros, Mark (Berkeley, CA); Madden, Norm W. (Livermore, CA); Goulding, Fred (Lafayette, CA); Landis, Don (Pinole, CA)

    1998-01-01

    A broad bandwidth high resolution x-ray fluorescence spectrometer has a performance that is superior in many ways to those currently available. It consists of an array of 4 large area microcalorimeters with 95% quantum efficiency at 6 keV and it produces x-ray spectra between 0.2 keV and 7 keV with an energy resolution of 7 to 10 eV. The resolution is obtained at input count rates per array element of 10 to 50 Hz in real-time, with analog pulse processing and thermal pile-up rejection. This performance cannot be matched by currently available x-ray spectrometers. The detectors are incorporated into a compact and portable cryogenic refrigerator system that is ready for use in many analytical spectroscopy applications as a tool for x-ray microanalysis or in research applications such as laboratory and astrophysical x-ray and particle spectroscopy.

  12. X-ray spectral evolution of high redshift quasars

    NASA Technical Reports Server (NTRS)

    Bechtold, Jill; Elvis, Martin; Fiore, Fabrizio; Kuhn, Olga; Cutri, Roc M.; Mcdowell, Jonathan C.; Rieke, Marcia; Siemiginowska, Aneta; Wilkes, Belinda J.

    1994-01-01

    At z approx. equals 3, the x-ray spectra of radio-loud and radio-quiet quasars are different. High-redshift radio-quiet quasars either have large absorbing columns, N(sub H), and steeper power law spectral indices, alpha(sub epsilon), than low redshift quasars, or no absorption and similar alpha(sub epsilon)'s. In contrast, the radio-loud quasars at high redshift have substantial absorption and similar alpha(sub epsilon)'s to low redshift quasars. Implications for the interpretation of the evolution of the luminosity function of quasars are discussed. If the absorption arises outside the central engine for both radio-loud and radio-quiet quasars, then radio-quiet quasars differ from the radio-loud quasars in that their emitted power law spectrum has evolved with redshift. We argue that this favors models where quasars are numerous and short-lived, rather than rare and long-lived.

  13. ISIS: Interactive Spectral Interpretation System for High Resolution X-Ray Spectroscopy

    NASA Astrophysics Data System (ADS)

    Houck, John C.; Davis, John E.; Huenemoerder, David; Dewey, Dan; Nowak, Mike; Davis, David S.

    2013-02-01

    ISIS, the Interactive Spectral Interpretation System, is designed to facilitate the interpretation and analysis of high resolution X-ray spectra. It is being developed as a programmable, interactive tool for studying the physics of X-ray spectrum formation, supporting measurement and identification of spectral features, and interaction with a database of atomic structure parameters and plasma emission models.

  14. X-Ray Spectral Variability in NGC 7469

    NASA Technical Reports Server (NTRS)

    Leighly, Karen; Kunieda, Hideyo; Awaki, Hisamitsu; Tsuruta, Sachiko

    1996-01-01

    We present analyses of two Ginga observations and two observations from the ROSAT database of NGC 7469, focusing on the spectral variability observed on timescales of days and longer. During the 1988 Ginga observation, the hardness ratio (8-21 keV/3.4-5.7 keV) increased significantly as the total flux decreased by 30%. As the spectrum is well fit by the reflection model and since the spectra variability dominates the higher energy band, this could be explained by either a variation in the power law index or in the effective covering fraction of the reflecting material. This ambiguity is inherent in reflection modeling of Ginga spectra from moderate flux Seyfert 1 galaxies. Assuming that the power law index did not change, we find that the reflected flux is consistent with being constant, suggesting that much of the reflecting material may be located more than 3 light-days from the continuum source with the molecular torus being a plausible site. This scenario is also supported by the report of a narrow rather than broad iron K-alpha line in the ASCA data by Guainazzi et al. NGC 7469 was faint during the 1989 Ginga observation, but variability was observed with doubling timescale of 5 hr, and the spectrum was harder. A reflection component could not be constrained, and the change in the spectrum could be explained by an increase in neutral absorption. The brighter of two ROSAT spectra was significantly softer, and in both spectra there was evidence of spectral complexity, as has been previously reported by Turner, George, & Mushotzky and Brandt et al. The spectrum could be fit by a variety of two-component models, including a warm absorber model, an ionized disk model, and a thermal model with single-component blackbody spectrum, but joint fitting of the 1988 average Ginga spectrum and the nonsimultaneous ROSAT spectra favored thermal models, and other models required an anomalously high reflection ratio. This model is supported by the observation of a soft excess component and the lack of ionized absorption edges in the ASCA spectrum by Guainazzi et al. The long-term spectral variability could be explained by relative variability between the power-law and soft excess component normalizations, perhaps implying that hard X-ray reprocessing in thermal material does not dominate on long timescales.

  15. High spectral resolution, high sensitivity microwave and associated hard X-ray bursts

    NASA Astrophysics Data System (ADS)

    Sawant, H. S.; Cecatto, J. R.; Dennis, B. R.; Gary, D. E.; Hurford, G. J.

    1993-09-01

    We have carried out mm-wavelength (18 - 23) GHz observations of solar bursts in June 1989, in Brazil. Nine of the bursts were observed simultaneously with the Hard X-ray Burst Spectrometer (HXRBS) on the Solar Maximum Mission (SMM). The Owens Valley Radio Observatory (OVRO) observed five of these events from 1 to 18 GHz. To date, we have analyzed six of these events and the preliminary results are: (i) The turnover frequency of all of these bursts were in the frequency range of 7 - 11 GHz and the radio spectral index ranged from -0.3 to -5.3 (ii) In three bursts, dominant features of high energy (>= 200 keV) X-rays coincided in time with mm-wavelength peaks, suggesting that the high energy electrons are responsible for the mm-wavelength emission.

  16. SPECTRAL SURVEY OF X-RAY BRIGHT ACTIVE GALACTIC NUCLEI FROM THE ROSSI X-RAY TIMING EXPLORER

    SciTech Connect

    Rivers, Elizabeth; Markowitz, Alex; Rothschild, Richard

    2011-03-15

    Using long-term monitoring data from the Rossi X-ray Timing Explorer (RXTE), we have selected 23 active galactic nuclei (AGNs) with sufficient brightness and overall observation time to derive broadband X-ray spectra from 3 to {approx}>100 keV. Our sample includes mainly radio-quiet Seyferts, as well as seven radio-loud sources. Given the longevity of the RXTE mission, the greater part of our data is spread out over more than a decade, providing truly long-term average spectra and eliminating inconsistencies arising from variability. We present long-term average values of absorption, Fe line parameters, Compton reflection strengths, and photon indices, as well as fluxes and luminosities for the hard and very hard energy bands, 2-10 keV and 20-100 keV, respectively. We find tentative evidence for high-energy rollovers in three of our objects. We improve upon previous surveys of the very hard X-ray energy band in terms of accuracy and sensitivity, particularly with respect to confirming and quantifying the Compton reflection component. This survey is meant to provide a baseline for future analysis with respect to the long-term averages for these sources and to cement the legacy of RXTE, and especially its High Energy X-ray Timing Experiment, as a contributor to AGN spectral science.

  17. X-Ray Spectral Study of the Photoionized Stellar Wind in Vela X-1

    SciTech Connect

    Watanabe, Shin; Sako, Masao; Ishida, Manabu; Ishisaki, Yoshitaka; Kahn, Steven M.; Kohmura, Takayoshi; Nagase, Fumiaki; Paerels, Frederik; Takahashi, Tadayuki; /JAXA, Sagamihara /KIPAC, Menlo Park /Tokyo Metropolitan U. /Kogakuin U. /Columbia U., Astron. Astrophys.

    2006-07-10

    We present results from quantitative modeling and spectral analysis of the high mass X-ray binary system Vela X-1 obtained with the Chandra High Energy Transmission Grating Spectrometer. The observations cover three orbital phase ranges within a single binary orbit. The spectra exhibit emission lines from H-like and He-like ions driven by photoionization, as well as fluorescent emission lines from several elements in lower charge states. The properties of these X-ray lines are measured with the highest accuracy to date. In order to interpret and make full use of the high-quality data, we have developed a simulator, which calculates the ionization and thermal structure of a stellar wind photoionized by an X-ray source, and performs Monte Carlo simulations of X-ray photons propagating through the wind. The emergent spectra are then computed as a function of the viewing angle accurately accounting for photon transport in three dimensions including dynamics. From comparisons of the observed spectra with results from the simulator, we are able to find the ionization structure and the geometrical distribution of material in the stellar wind of Vela X-1 that can reproduce the observed spectral line intensities and continuum shapes at different orbital phases remarkably well. We find that the stellar wind profile can be represented by a CAK-model with a star mass loss rate of (1.5-2.0) x 10{sup -6} M{sub {circle_dot}} yr{sup -1}, assuming a terminal velocity of 1100 km s{sup -1}. It is found that a large fraction of X-ray emission lines from highly ionized ions are formed in the region between the neutron star and the companion star. We also find that the fluorescent X-ray lines must be produced in at least three distinct regions: (1) the extended stellar wind, (2) reflection off the stellar photosphere, and (3) in a distribution of dense material partially covering and possibly trailing the neutron star, which may be associated with an accretion wake. Finally, from detailed analysis of the emission line profiles, we demonstrate that the stellar wind dynamics is affected by X-ray photoionization.

  18. X-ray communication based simultaneous communication and ranging

    NASA Astrophysics Data System (ADS)

    Song, Shi-Bin; Xu, Lu-Ping; Zhang, Hua; Gao, Na

    2015-09-01

    To improve the link efficiency and decrease the payloads in space explorations, a novel simultaneous communication and ranging method based on x-ray communication (XCOM) is proposed in this paper. A delicate signal symbol structure is utilized to achieve simultaneous data transmission and range measurement. With the designed symbol structure, the ranging information is imbedded into the communication signal and transmitted with it simultaneously. The range measurement is realized by the two-way transmission of the range information. To illustrate the proposed method, firstly, the principle of the method is introduced and the signal processing procedure is presented. Then, the performance of the proposed method is analyzed theoretically in various aspects, including the acquisition probability, the bit error rate, the ranging jitter, etc. Besides, numerical experiments are conducted to verify the proposed method and evaluate the system performance. The simulation results show that the proposed method is feasible and that the system performance is influenced by the parameters concerning the signal symbol structure. Compared with the previous methods, the proposed method improves the link efficiency and is beneficial for system miniaturization and integration, which could provide a potential option for future deep space explorations. Project supported by the National Natural Science Foundation of China (Grant Nos. 61172138 and 61401340), the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20130203120004), and the Fundamental Research Funds for the Central Universities, China (Grant Nos. 201413B, 201412B, and JB141303).

  19. Feasibility of a spectral imager in the soft x-ray region

    NASA Astrophysics Data System (ADS)

    Wilcox, Jaroslava; White, Victor; Shcheglov, Kirill

    2009-05-01

    The development of Fourier Transform (FT) spectral techniques in the soft X-ray (100eV to 500eV spectral region) has been advocated in the past as a possible route to constructing a bench-top size spectral imager with high spatial and spectral resolution. The crux of the imager is the soft X-ray interferometer. The auxiliary subsystems include a soft X-ray source, focusing optics and a CCD-based detection system. When tuned over a sufficiently large range of path delays (frames), the interferometer will sinusoidally modulate a spectrum of a wide-band X-ray source centered at the core wavelength of interest with high resolving power. The spectrum illuminates a target, the reflected signal is imaged onto a CCD, and data acquired for different frames is converted to spectra in software by using FT methods similar to those used in IR spectrometry, producing spectral image per each pixel. The use of short wavelengths results in dramatic increase in imaging resolution over that for IR. Important for future NASA missions, and unlike X-ray Absorption Near Edge Structure (XANES) that uses intense and in monochromatic beams which only a synchrotron can deliver, FTXR plans to use a miniature, wide bandwidth X-ray source. By modulating the beam spectrum around the wavelength of interest, the beam energy is used much more efficiently than with gratings (when only a very small, monochromatized portion of the radiation is used at one time) facilitating construction of a bench-top instrument. With the predicted <0.1eV spectral and <100 nm spatial resolution, the imager would be able to map a core-level shift spectrum for each pixel of the image for elements such as C, Si, Ca, N (K?-lines) which can be used as a chemical compound fingerprint and for imaging intracellular structures. For heavy elements it could provide "bonding maps" (L and M-shell lines), enabling to study fossils of microorganisms on space missions and in returned samples to Earth. We have initiated development of a Fourier Transform X-ray Reflection (FTXR) spectral imager based on the use of a Mach-Zender type interferometer. The enabling technology for the interferometer is the X-ray beam splitting mirrors. The mirrors are not available commercially; multi layers of quarter-wave films are not suitable, requiring a different approach to beam-splitters than in the visible or IR regions. Several efforts by other researchers used parallel slits or stripes for partial transmission, with only a very limited success. In contrast, our beam splitters are based on thin (about 200 nm) SiN membranes perforated with a large number of very small holes, prepared using state-of-art microfabrication techniques that have only recently become available in our laboratory at JPL. Precise control of surface roughness and high planarity are needed to achieve the wave coherency required for high-contrast fringe forming. The perforation design is expected to result in much greater surface flatness, facilitating greater wave coherence than for the other techniques. We report on our progress in the fabrication of beam splitting mirrors to-date, interferometer design, modeling, assembly, and experimental results.

  20. Spectral and Temporal Characteristics of X-Ray-Bright Stars in the Pleiades

    NASA Technical Reports Server (NTRS)

    Gagne, Marc; Caillault, Jean-Pierre; Stauffer, John R.

    1995-01-01

    We follow up our deep ROSAT imaging survey of the Pleiades (Stauffer et al. 1994) with an analysis of the spectral and temporal characteristics of the X-ray-bright stars in the Pleiades. Raymond & Smith (1977) one and two-temperature models have been used to fit the position-sensitive proportional counter (PSPC) pulse-height spectra of the dozen or so brightest sources associated with late-type Pleiades members. The best-fit temperatures suggest hot coronal temperatures for K, M, and rapidly rotating G stars, and cooler temperatures for F and slowly rotating G stars. In order to probe the many less X-ray-luminous stars, we have generated composite spectra by combining net counts from all Pleiades members according to spectral type and rotational velocity. Model fits to the composite spectra confirm the trend seen in the individual spectral fits. Particularly interesting is the apparent dependence of coronal temperature on L(sub x)/L(sub bol). A hardness-ratio analysis also confirms some of these trends. The PSPC data have also revealed a dozen or so strong X-ray flares with peak X-ray luminosities in excess of approx. 10(exp 30) ergs/sec. We have modeled the brightest of these flares with a simple quasi-static cooling loop model. The peak temperature and emission measure and the inferred electron density and plasma volume suggest a very large scale flaring event. The PSPC data were collected over a period of approx. 18 months, allowing us to search for source variability on timescales ranging from less than a day (in the case of flares) to more than a year between individual exposures. On approximately year-long timescales, roughly 25% of the late-type stars are variable. Since the Pleiades was also intensively monitored by the imaging instruments on the Einstein Observatory, we have examined X-ray luminosity variations on the 10 yr timescale between Einstein and ROSAT and find that up to 40% of the late-type stars are X-ray variable. Since there is only marginal evidence for increased variability on decade-long timescales, the variability observed on long and short timescales may have a common physical origin.

  1. Small, Fast TES Microcalorimeters with Unprecedented X-ray Spectral Performance

    NASA Technical Reports Server (NTRS)

    Eckart, M. E.; Adams, J. S.; Bailey, C. N.; Bandler, S. R.; Chervenak, J. A.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. S.; Sadleir, J. E.; Smith, S. J.; Hilton, G. C.; Irwin, K. D.; Vale, L. R.

    2011-01-01

    Driven initially by the desire for X-ray microcalorimeter arrays suitable for imaging the dynamic solar corona, we have developed a transition-edge-sensor (TES) microcalorimeter optimization that exhibits a unique combination of high spectral resolving power and a wide X-ray bandpass. These devices have achieved spectral performance of dE approximately 1.3 eV FWHM at 1.5 keV, 1.6 eV at 6 keV, and 2.0 eV at 8 keV, using small TESs (e.g., approximately 35 micron x 35 micron) that operate in a regime in which the superconducting transition is highly current dependent. In order to accommodate high X-ray count rates, the devices sit directly on a solid substrate instead of on membranes, and we use an embedded heatsinking layer to reduce pixel-to-pixel crosstalk. We will present results from devices with a range of TES and absorber sizes, and from device wafers with varied embedded heatsink materials. This contribution will focus on count-rate capabilities, including a discussion of the trade-off between count rate and energy resolution, and the heatsinking design. We will also present preliminary tests of array readout using a code-division multiplexed SQUID readout scheme, which may be necessary to enable large arrays of these fast devices.

  2. Development of a stacked detector system for the x-ray range and its possible applications

    NASA Astrophysics Data System (ADS)

    Maier, Daniel; Limousin, Olivier; Meuris, Aline; Prckhauer, Sabina; Santangelo, Andrea; Schanz, Thomas; Tenzer, Christoph

    2014-07-01

    We have constructed a stacked detector system operating in the X-ray range from 0.5 keV to 250 keV that consists of a Si-based 6464 DePFET-Matrix in front of a CdTe hybrid detector called Caliste-64. The setup is operated under laboratory conditions that approximate the expected environment of a space-borne observatory. The DePFET detector is an active pixel matrix that provides high count-rate capabilities with a near Fanolimited spectral resolution at energies up to 15 keV. The Caliste-64 hard X-ray camera consists of a 1mm thick CdTe crystal combined with very compact integrated readout electronics, constituting a high performance spectro-imager with event-triggered time-tagging capability in the energy range between 2 keV and 200 keV. In this combined geometry the DePFET detector works as the Low Energy Detector (LED) while the Caliste-64 - as the High Energy Detector (HED) - detects predominantly the high energetic photons that have passed the LED. In addition to the individual optimization of both detectors, we use the setup to test and optimize the performance of the combined detector system. Side-effects like X-ray fluorescence photons, electrical crosstalk, and mutual heating have negative impacts on the data quality and will be investigated. Besides the primary application as a combined imaging detector system with high sensitivity across a broad energy range, additional applications become feasible. Via the analysis of coincident events in both detectors we can estimate the capabilities of the setup to be used as a Compton camera and as an X-ray polarimeter - both desirable functionalities for use in the lab as well as for future X-ray missions.

  3. Diagnosing x-ray power and energy of tungsten wire array z-pinch with a flat spectral response x-ray diode

    NASA Astrophysics Data System (ADS)

    Wang, Kun-lun; Ren, Xiao-dong; Huang, Xian-bin; Zhang, Si-qun; Zhou, Shao-tong; Dan, Jia-kun; Li, Jing; Xu, Qiang; Ouyang, Kai; Cai, Hong-chun; Wei, Bing; Ji, Ce; Feng, Shu-ping; Wang, Meng; Xie, Wei-ping; Deng, Jian-jun

    2015-11-01

    Fast z-pinch is a very efficient way of converting electromagnetic energy to radiation. With an 8-10 MA current on primary test stand facility, about 1 MJ electromagnetic energy is delivered to vacuum chamber, which heats z-pinch plasma to radiate soft x-ray. To develop a pulsed high power x-ray source, we studied the applicability of diagnosing x-ray power from tungsten wire array z-pinch with a flat spectral response x-ray diode (FSR-XRD). The detector was originally developed to diagnose radiation of a hohlraum in SG-III prototype laser facility. It utilized a gold cathode XRD and a specially configured compound gold filter to yield a nearly flat spectral response in photon energy range of 0.1-4 keV. In practice, it was critical to avoid surface contamination of gold cathode. It is illustrated that an exposure of an XRD to multiple shots caused a significant change of response. Thus, in diagnosing x-ray power and energy, we used each XRD in only one shot after calibration. In a shot serial, output of FSR-XRD was compared with output of a nickel bolometer. In these shots, the outputs agreed with each other within their uncertainties which were about 12% for FSR-XRD and about 15% for bolometer. Moreover, the ratios between the FSR-XRD and the bolometer among different shots were explored. In 8 shots, the standard deviation of the ratio was 6%. It is comparable to XRD response change of 7%.

  4. Diagnosing x-ray power and energy of tungsten wire array z-pinch with a flat spectral response x-ray diode.

    PubMed

    Wang, Kun-Lun; Ren, Xiao-Dong; Huang, Xian-Bin; Zhang, Si-Qun; Zhou, Shao-Tong; Dan, Jia-Kun; Li, Jing; Xu, Qiang; Ouyang, Kai; Cai, Hong-Chun; Wei, Bing; Ji, Ce; Feng, Shu-Ping; Wang, Meng; Xie, Wei-Ping; Deng, Jian-Jun

    2015-11-01

    Fast z-pinch is a very efficient way of converting electromagnetic energy to radiation. With an 8-10 MA current on primary test stand facility, about 1 MJ electromagnetic energy is delivered to vacuum chamber, which heats z-pinch plasma to radiate soft x-ray. To develop a pulsed high power x-ray source, we studied the applicability of diagnosing x-ray power from tungsten wire array z-pinch with a flat spectral response x-ray diode (FSR-XRD). The detector was originally developed to diagnose radiation of a hohlraum in SG-III prototype laser facility. It utilized a gold cathode XRD and a specially configured compound gold filter to yield a nearly flat spectral response in photon energy range of 0.1-4 keV. In practice, it was critical to avoid surface contamination of gold cathode. It is illustrated that an exposure of an XRD to multiple shots caused a significant change of response. Thus, in diagnosing x-ray power and energy, we used each XRD in only one shot after calibration. In a shot serial, output of FSR-XRD was compared with output of a nickel bolometer. In these shots, the outputs agreed with each other within their uncertainties which were about 12% for FSR-XRD and about 15% for bolometer. Moreover, the ratios between the FSR-XRD and the bolometer among different shots were explored. In 8 shots, the standard deviation of the ratio was 6%. It is comparable to XRD response change of 7%. PMID:26628136

  5. Nonthermal X-ray Spectral Flattening toward Low Energies in Early Impulsive Flares

    NASA Technical Reports Server (NTRS)

    Holman, Gordon D.

    2007-01-01

    The determination of the low-energy cutoff to nonthermal electron distributions is critical to the calculation of the nonthermal energy in solar flares. The most direct evidence for low-energy cutoffs is flattening of the power-law, nontherma1 X-ray spectra at low energies. However, because of the plasma preheating often seen in flares, the thermal emissions at low energies may hide such spectral flattening of the nonthermal component. We select a category of flares, which we call "early impulsive flares", in which the > 25 keV hard X-ray (HXR) flux increase is delayed by less than 30 s after the flux increase at lower energies. Thus, the plasma preheating in these flares is minimal, so the nonthermal spectrum can be determined to lower energies than in flares with significant preheating. Out of a sample of 33 early impulsive flares observed by the Ramaty High Energy Solar Spectroscopy Imager (RHESSI), 9 showed spectral flattening toward low energies. In these events, the break energy of the double power-law fit to the HXR spectra lies in the range of 10-50 keV, significantly lower than the value we have seen for other flares that do not show such early impulsive emissions. In particular, it correlates with the HXR flux. After correcting the spatially-integrated spectra for albedo from isotropically emitted X-rays and using RHESSI imaging spectroscopy to exclude the extended albedo halo, we find that albedo associated with isotropic or nearly isotropic electrons can only account for the spectral flattening in 3 flares near Sun center. The spectral flattening in the remaining 6 flares is found to be consistent with the existence of a low-energy cutoff in the electron spectrum, falling in the range of 15-50 keV, which also correlates with the HXR flux.

  6. Spectral brilliance of parametric X-rays at the FAST facility

    SciTech Connect

    Sen, Tanaji; Seiss, Todd

    2015-06-22

    We discuss the generation of parametric X-rays in the new photoinjector at the FAST (Fermilab Accelerator Science and Technology) facility in Fermilab. These experiments will be conducted in addition to channeling X-ray radiation experiments. The low emittance electron beam makes this facility a promising source for creating brilliant X-rays. We discuss the theoretical model and present detailed calculations of the intensity spectrum, energy and angular widths and spectral brilliance under different conditions. Furthermore, we report on expected results with parametric X-rays generated while under channeling conditions.

  7. Spectral Properties of Blazars. II. an X-Ray Observed Sample

    NASA Astrophysics Data System (ADS)

    Maraschi, L.; Ghisellini, G.; Tanzi, E. G.; Treves, A.

    1986-11-01

    All the blazars observed in X-rays in various reference lists and all those belonging to X-ray selected samples are considered. It is found that X-ray selected objects have, on average, radio (5 GHz) to ultraviolet (2500 ) and ultraviolet to X-ray (2 keV) spectral indices significantly flatter than radio-selected objects. The monochromatic luminosity distributions show that X-ray selected and radio-selected blazars have the same average X-ray luminosity, and that the X-ray selected ones are underluminous at ultraviolet and radio frequencies. It is argued that the objects with flat overall spectrum, which may be called radio-weak, discovered from X-ray searches are the dominant members of the blazar population in terms of space density, while radio-loud blazars with the same X-ray luminosity are a minority. The results are interpreted in the framework of a model where the X-ray emission is isotropic, while that at lower frequencies is relativistically beamed. Radio-loud blazars should be those with the beam pointing towards us.

  8. Hard X-Ray Imaging of Individual Spectral Components in Solar Flares

    NASA Astrophysics Data System (ADS)

    Caspi, Amir; Shih, Albert Y.; McTiernan, James M.; Krucker, Sm

    2015-09-01

    We present a new analytical technique, combining Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) high-resolution imaging and spectroscopic observations, to visualize solar flare emission as a function of spectral component (e.g., isothermal temperature) rather than energy. This computationally inexpensive technique is applicable to all spatially invariant spectral forms and is useful for visualizing spectroscopically determined individual sources and placing them in context, e.g., comparing multiple isothermal sources with nonthermal emission locations. For example, while extreme ultraviolet images can usually be closely identified with narrow temperature ranges, due to the emission being primarily from spectral lines of specific ion species, X-ray images are dominated by continuum emission and therefore have a broad temperature response, making it difficult to identify sources of specific temperatures regardless of the energy band of the image. We combine RHESSI calibrated X-ray visibilities with spatially integrated spectral models including multiple isothermal components to effectively isolate the individual thermal sources from the combined emission and image them separately. We apply this technique to the 2002 July 23 X4.8 event studied in prior works, and image for the first time the super-hot and cooler thermal sources independently. The super-hot source is farther from the footpoints and more elongated throughout the impulsive phase, consistent with an in situ heating mechanism for the super-hot plasma.

  9. Extended range X-ray telescope: X-ray microscope design

    NASA Technical Reports Server (NTRS)

    Shealy, D. L.; Kassim, A.; Chao, S.

    1982-01-01

    A glancing incidence X-ray microscope using a confocal hyperboloid ellipsoid mirror was designed to couple optically a Wolter 1 telescope to a CCD focal plane detector. Both the RMS spot size and the point spread function calculations were used to evaluate the resolution, defocusing, and vignetting effects of the system for microscope focal lengths of 1, 1.5, and 2 meters and for magnifications varying from 2 to 10x. For the specific application with the S-056 telescope, a 2 meter, 8x microscope with a fabrication ratio of the microscope mirror length to the inner diameter at hyperboloid ellipsoid intersection of 2.5 was designed to be used with a thinned, back illuminated CCD detector array with 320 by 512, 30 micron pixels.

  10. Possible application of X-ray optical elements for reducing the spectral bandwidth of an X-ray SASE FEL

    NASA Astrophysics Data System (ADS)

    Feldhaus, J.; Saldin, E. L.; Schneider, J. R.; Schneidmiller, E. A.; Yurkov, M. V.

    1997-08-01

    A new design for a single pass X-ray Self-Amplified Spontaneous Emission (SASE) FEL is proposed. The scheme consists of two undulators and an X-ray monochromator located between them. The first stage of the FEL amplifier operates in the SASE linear regime. After the exit of the first undulator the electron bunch is guided through a non-isochronous bypass and the X-ray beam enters the monochromator. The main function of the bypass is to suppress the modulation of the electron beam induced in the first undulator. This is possible because of the finite value of the natural energy spread in the beam. At the entrance to the second undulator the radiation power from the monochromator dominates significantly over the shot noise and the residual electron bunching. As a result the second stage of the FEL amplifier operates in the steady-state regime when the input signal bandwidth is small with respect to that of the FEL amplifier. Integral losses of the radiation power in the monochromator are relatively small because grazing incidence optics can be used. The proposed scheme is illustrated for the example of the 6 nm option SASE FEL at the TESLA Test Facility under construction at DESY. As shown in this paper the spectral bandwidth of such a two-stage SASE FEL (??/?? 5 10-5) is close to the limit defined by the finite duration of the radiation pulse. The average brilliance is equal to 7 1024photons/(s mrad2 mm2 0.1% bandw.) which is by two orders of magnitude higher than the value which could be reached by the conventional SASE FEL. The monochromatization of the radiation is performed at a low level of radiation power (about 500 times less than the saturation level) which allows one to use conventional X-ray optical elements (grazing incidence grating and mirrors) for the monochromator design.

  11. Photon counting spectral CT: improved material decomposition with K-edge-filtered x-rays.

    PubMed

    Shikhaliev, Polad M

    2012-03-21

    Photon counting spectral computed tomography (PCSCT) provides material selective CT imaging at a single CT scan and fixed tube voltage. The PCSCT data are acquired in several energy ranges (bins) arranged over the x-ray spectrum. The quasi-monoenergetic CT images are acquired in these energy bins and are used for material decomposition. The PCSCT exhibits inherent limitations when material decomposition is performed using energy bins. For effective material decomposition, the energy bins used for material decomposition should be sufficiently narrow and well separated. However, when narrow bins are used, a large fraction of the detected x-ray counts is lost and statistical noise is increased. Alternatively, the x-ray spectrum can be split into a few larger bins with no gap in between and all detected x-ray photons can be used for material decomposition. However, in this case the energy bins are too wide and not well separated, which results in suboptimal material decomposition. The above contradictory requirements can be resolved if the x-ray photons are physically removed from the regions of the energy spectrum between the energy bins. Such a selective removal can be performed using filtration of the x-ray beam by high-Z filter materials with appropriate positions of K-edge energies. The K-edge filtration of x-rays can, therefore, provide necessary gaps between the energy bins with no dose penalty to the patient. In the current work, we proposed using selective K-edge filtration of x-rays in PCSCT and performed the first experimental investigation of this approach. The PCSCT system included a cadmium zinc telluride semiconductor detector with 2 256 pixels and 1 1 mm(2) pixel size, and five energy bins. The CT phantom had 14 cm diameter and included contrast elements of iodine, gold and calcifications with clinically relevant concentrations. The tube voltages of 60, 90 and 120 kVp were used. K-edge filters based on Ba (E(k) = 37.44 keV) were used for a 60 kVp tube voltage and Gd (E(k) = 50.24 keV) was used for the 90 and 120 kVp tube voltages, respectively. The material selective CT images were also acquired with conventional Al filtration for comparison. The half-value layers of x-ray beams after K-edge and Al filtration were matched. The mean entrance skin exposure was 280 mR for all tube voltages and filters. The contrast-to-noise ratio (CNR) in material-decomposed images was approximately 30%-50% higher when K-edge filters were used instead of Al filters. It was concluded that K-edge filtration of x-rays provides substantial improvement of the CNR in material-selective PCSCT. Further optimization of K-edge filter materials, tube voltages, detector technology and energy bin settings will provide even higher CNR in decomposed images. PMID:22398007

  12. Method of x-ray spectral fluorescence analysis with corrections for the perturbing effect of elements

    SciTech Connect

    Pavlinskii, G.V.

    1986-01-01

    A new method of x-ray spectral analysis with corrections for the perturbing effects of elements, based on the existing theory of perturbation of x-ray flourescence, has been proved and tested on calculated and experimental intensities. The laborious computational operations are performed at the preliminary stage of analysis, which enables it to be used on analytical assemblies with a low-capacity computer. The investigations carried out enable the proposed method to be recommended for the x-ray spectral analysis of homogeneous material.

  13. Thermal X-ray spectral tools. I. Parameterizing impulsive X-ray heating with a cumulative initial temperature (CIT) distribution

    SciTech Connect

    Gayley, Kenneth G.

    2014-06-10

    In collisional ionization equilibrium, the X-ray spectrum from a plasma depends on the differential emission measure (DEM), distributed over temperature. Due to the well-known ill conditioning problem, no precisely resolved DEM can be inverted directly from the spectrum, so often only a gross parameterization of the DEM is used to approximate the data, in hopes that the parameterization can provide useful model-independent constraints on the heating process. However, ill conditioning also introduces ambiguity into the various different parameterizations that could approximate the data, which may spoil the perceived advantages of model independence. Thus, this paper instead suggests a single parameterization for both the heating mechanism and the X-ray sources, based on a model of impulsive heating followed by radiative cooling. This approach is similar to a 'cooling flow' approach but allows injection at multiple initial temperatures and applies even when the steady state is a distribution of different shock strengths, as for a standing shock with a range of obliquities, or for embedded stochastic shocks that are only steady in a statistical sense. This produces an alternative parameterization for X-ray spectra that is especially streamlined for higher density plasmas with efficient radiative cooling and minimal thermal conduction and mixing. The method also provides some internal consistency checks on the validity of its assumptions. A heuristic general version is then applied over a wide range of astrophysical applications to schematically explore potential alternative models for these phenomena.

  14. Thermal X-Ray Spectral Tools. I. Parameterizing Impulsive X-Ray Heating with a Cumulative Initial Temperature (CIT) Distribution

    NASA Astrophysics Data System (ADS)

    Gayley, Kenneth G.

    2014-06-01

    In collisional ionization equilibrium, the X-ray spectrum from a plasma depends on the differential emission measure (DEM), distributed over temperature. Due to the well-known ill conditioning problem, no precisely resolved DEM can be inverted directly from the spectrum, so often only a gross parameterization of the DEM is used to approximate the data, in hopes that the parameterization can provide useful model-independent constraints on the heating process. However, ill conditioning also introduces ambiguity into the various different parameterizations that could approximate the data, which may spoil the perceived advantages of model independence. Thus, this paper instead suggests a single parameterization for both the heating mechanism and the X-ray sources, based on a model of impulsive heating followed by radiative cooling. This approach is similar to a "cooling flow" approach but allows injection at multiple initial temperatures and applies even when the steady state is a distribution of different shock strengths, as for a standing shock with a range of obliquities, or for embedded stochastic shocks that are only steady in a statistical sense. This produces an alternative parameterization for X-ray spectra that is especially streamlined for higher density plasmas with efficient radiative cooling and minimal thermal conduction and mixing. The method also provides some internal consistency checks on the validity of its assumptions. A heuristic general version is then applied over a wide range of astrophysical applications to schematically explore potential alternative models for these phenomena.

  15. The X-ray spectral properties of very-faint persistent neutron star X-ray binaries

    NASA Astrophysics Data System (ADS)

    Armas Padilla, M.; Degenaar, N.; Wijnands, R.

    2013-09-01

    AX J1754.2-2754, 1RXS J171824.2-402934 and 1RXH J173523.7-354013 are three persistent neutron star low-mass X-ray binaries that display a 2-10 keV accretion luminosity LX of only (1-10) 1034 erg s-1 (i.e. only ?0.005-0.05 per cent of the Eddington limit). The phenomenology of accreting neutron stars which accrete at such low accretion rates is not yet well known and the reason why they have such low accretion rates is also not clear. Therefore, we have obtained XMM-Newton data of these three sources and here we report our analysis of the high-quality X-ray spectra we have obtained for them. We find that AX J1754.2-2754 has LX 1035 erg s-1, while the other two have X-ray luminosities about an order of magnitude lower. However, all sources have a similar, relatively soft, spectrum with a photon index of 2.3-2.5, when the spectrum is fitted with an absorbed power-law model. This model fits the data of AX J1754.2-2754 adequately, but it cannot fit the data obtained for 1RXS J171824.2-402934 and 1RXH J173523.7-354013. For those sources, a clear soft thermal component is needed to fit their spectra. This soft component contributes 40-50 per cent to the 0.5-10 keV flux of the sources. The presence of this soft component might be the reason why the spectra of these two sources are soft. When including this additional spectral component, the power-law photon indices are significantly lower. It can be excluded that a similar component with similar contributions to the 2-10 keV X-ray flux is present for AX J1754.2-2754, indicating that the soft spectrum of this source is mostly due to the fact that the power-law component itself is not hard. We note that we cannot exclude that a weaker soft component is present in the spectrum of this source which only contributes up to 25 per cent to the 0.5-10 keV X-ray flux. We discuss our results in the context of what is known of accreting neutron stars at very low accretion rate.

  16. Characteristics of transition radiation in the x-ray spectral region

    SciTech Connect

    Moran, M.J.

    1986-06-06

    Measurements of soft x-ray production by transition radiation have been performed in a series of experiments at the Lawrence Livermore National Laboratory. The results have shown that transition radiation is an intense and predictable source of photons in the soft x-ray energy range. This paper will give a brief review of the general properties of the x-ray distributions generated by these sources. 9 refs., 9 figs.

  17. Spectral and temporal properties of the X-ray pulsar SMC X-1 at hard X-rays

    NASA Technical Reports Server (NTRS)

    Kunz, M.; Gruber, D. E.; Kendziorra, E .; Kretschmar, P.; Maisack, M.; Mony, B.; Staubert, R.; Doebereiner, S.; Englhauser, J.; Pietsch, W.

    1993-01-01

    The binary X-ray pulsar SMC X- 1 has been observed at hard X-rays with the High Energy X-Ray Experiment (HEXE) on nine occasions between Nov. 1987 and March 1989. A thin thermal bremsstrahlung fit to the phase averaged spectrum yields a plasma temperature (14.4 +/- 1.3) keV and a luminosity above (1.1 +/- 0.1) x 10 exp 38 erg/s in the 20-80 keV band. Pulse period values have been established for three observations, confirming the remarkably stable spin-up trend of SMC X-1. In one of the three observations the pulse profile was seen to deviate from a dominant double pulsation, while at the same time the pulsed fraction was unusually large. For one observation we determined for the first time the pulsed fraction in narrow energy bands. It increases with photon energy from about 20 percent up to over 60 percent in the energy range from 20 to 80 keV.

  18. Spectral filtering optimization of a measuring channel of an x-ray broadband spectrometer

    NASA Astrophysics Data System (ADS)

    Emprin, B.; Troussel, Ph.; Villette, B.; Delmotte, F.

    2013-05-01

    A new channel of an X-ray broadband spectrometer has been developed for the 2 - 4 keV spectral range. It uses a spectral filtering by using a non-periodic multilayer mirror. This channel is composed by a filter, an aperiodic multilayer mirror and a detector. The design and realization of the optical coating mirror has been defined such as the reflectivity is above 8% in almost the entire bandwidth range 2 - 4 keV and lower than 2% outside. The mirror is optimized for working at 1.9° grazing incidence. The mirror is coated with a stack of 115 chromium / scandium (Cr / Sc) non-periodic layers, between 0.6 nm and 7.3 nm and a 3 nm thick top SiO2 layer to protect the stack from oxidization. To control thin thicknesses, we produced specific multilayer mirrors which consist on a superposition of two periodic Cr / Sc multilayers with the layer to calibrate in between. The mirror and subnanometric layers characterizations were made at the "Laboratoire Charles Fabry" (LCF) with a grazing incidence reflectometer working at 8.048 keV (Cu Kα radiation) and at the synchrotron radiation facility SOLEIL on the hard X-ray branch of the "Metrology" beamline. The reflectivity of the mirrors as a function of the photon energy was obtained in the Physikalisch Technische Bundesanstalt (PTB) laboratory at the synchrotron radiation facility Bessy II.

  19. The spectral archive of cosmic X-ray sources observed by the Einstein Observatory Focal Plane Crystal Spectrometer

    NASA Technical Reports Server (NTRS)

    Lum, Kenneth S. K.; Canizares, Claude R.; Clark, George W.; Coyne, Joan M.; Markert, Thomas H.; Saez, Pablo J.; Schattenburg, Mark L.; Winkler, P. F.

    1992-01-01

    The Einstein Observatory Focal Plane Crystal Spectrometer (FPCS) used the technique of Bragg spectroscopy to study cosmic X-ray sources in the 0.2-3 keV energy range. The high spectral resolving power (E/Delta-E is approximately equal to 100-1000) of this instrument allowed it to resolve closely spaced lines and study the structure of individual features in the spectra of 41 cosmic X-ray sources. An archival summary of the results is presented as a concise record the FPCS observations and a source of information for future analysis by the general astrophysics community. For each observation, the instrument configuration, background rate, X-ray flux or upper limit within the energy band observed, and spectral histograms are given. Examples of the contributions the FPCS observations have made to the understanding of the objects observed are discussed.

  20. An X-ray Spectral Survey of Radio-Loud AGN with ASCA

    NASA Astrophysics Data System (ADS)

    Sambruna, R. M.; Eracleous, M.; Mushotzky, R. F.

    1999-05-01

    We present a systematic X-ray spectral survey with ASCA of a sample of radio-loud AGN, including 9 Broad Line Radio Galaxies (BLRGs), 6 Quasars (QSRs), 12 Narrow Line Radio Galaxies (NLRGs), and 11 Radio Galaxies (RGs). At soft X-rays, 50% NLRGs and 100% RGs exhibit a thermal component, indicating emission from either a cluster or a loose group or hot corona. At energies > 2 keV, a hard power-law is detected, with similar slopes (photon index Gamma ~ 1.7) and luminosities in BLRGs, QSRs, and NLRGs, consistent with simple orientation-based unification schemes. Excess cold absorption in the range 10(21-24) cm(-2) is detected in most NLRGs, most likely due to an obscuring torus. Absorption edges of ionized oxygen, common in Seyfert 1s, are detected in only one BLRG. Instead large columns of cold gas, comparable to NLRGs, are detected in a fraction of BLRGs and QSRs, which is puzzling. The nuclear X-ray luminosity is non-linearly correlated with the [OIII] emission line luminosity, the FIR 12 mu m emission, and 5 GHz lobe radio power. The Fe Kalpha line is detected in 50% BLRGs and one QSR, with a large range of intrinsic widths and equivalent widths, while it is unresolved in NLRGs. There is only a weak indication that the ASCA spectra of BLRGs are flatter than Seyfert 1s of comparable X-ray luminosity, contrary to previous evidence. The sample includes 6 Weak Line Radio Galaxies (WLRGs), characterized by underluminous [OIII] lines and unusually high [OII]/[OIII] ratios. Their ASCA spectra are consistent at hard energies with a hard (Gamma ~ 1.5) power law, with intrinsic luminosities 100 times lower than in other RGs. If the hard X-ray emission is attributed to a low-luminosity AGN, an interesting possibility is that WLRGs are accreting at strongly sub-Eddington rates. This work is supported by NASA contract NAS-38252 and NASA grant NAG5-7733

  1. X-ray spectral diagnostics of synthetic lanthanide silicates

    NASA Astrophysics Data System (ADS)

    Kravtsova, A. N.; Guda, A. A.; Soldatov, A. V.; Goettlicher, J.; Taroev, V. K.; Kashaev, A. A.; Suvorova, L. F.; Tauson, V. L.

    2015-12-01

    Potassium and rare-earth (Eu, Sm, Yb, Ce) silicate and aluminosilicate crystals are hydrothermally synthesized under isothermal conditions at 500C and a pressure of 100 MPa. The chemical and structural formulas of the synthesized compounds HK6Eu[Si10O25], K7Sm3[Si12O32], K2Sm[AlSi4O12] 0.375H2O, K4Yb2[Si8O21], and K4Ce2[Al2Si8O24] are determined. In addition, a synthesis product with Eu, in which the dominant phase is assumed to be K3Eu3+[Si6O15] 2H2O, is studied. The oxidation state of lanthanides in the silicates under study is determined based on X-ray absorption near-edge structure spectroscopy. The Eu L 3-, Sm L 3-, Yb L 3-, and Ce L 3-edge X-ray absorption spectra of the studied silicates and reference samples are recorded using a Rigaku R-XAS laboratory spectrometer. As reference samples, Eu2+S, Eu3+F3, Eu 2 3+ O3, Sm 2 3+ O3, Yb 2 3+ O3, Yb3+F3, Yb3+Cl3, Ce 2 3+ O3, and Ce4+O2 are used. Comparison of the absorption edge energies of lanthanide silicates and reference samples shows that Eu, Sm, Yb, and Ce in all the samples studied are in the oxidation state 3+. The synthesized silicates will supplement our knowledge of possible rare-earth minerals existing in hydrothermal systems, which is important for analyzing the distribution spectra of rare elements, which are widely used for diagnostics of geochemical processes and determination of sources of ore materials.

  2. Spectral Properties, Generation Order Parameters, and Luminosities for Spin-powered X-Ray Pulsars

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Zhao, Yongheng

    2004-02-01

    We show the spectral properties of 15 spin-powered X-ray pulsars, and the correlation between the average power-law photon index and spin-down rate. Generation order parameters (GOPs) based on polar cap models are introduced to characterize the X-ray pulsars. We calculate three definitions of generation order parameters arising from the different effects of magnetic and electric fields on photon absorption during cascade processes, and study the relations between the GOPs and spectral properties of X-ray pulsars. There exists a possible correlation between the photon index and GOP in our pulsar sample. Furthermore, we present a method stemming from the concept of GOPs to estimate the nonthermal X-ray luminosity for spin-powered pulsars. Then X-ray luminosity is calculated in the context of our polar cap accelerator model, which is consistent with most observed X-ray pulsar data. The ratio between the X-ray luminosity estimated by our method and the pulsar's spin-down power is consistent with the LX~10-3Lsd feature.

  3. The influence of accretion geometry on the spectral evolution during thermonuclear (type I) X-ray bursts

    NASA Astrophysics Data System (ADS)

    Kajava, Jari J. E.; Nättilä, Joonas; Latvala, Outi-Marja; Pursiainen, Miika; Poutanen, Juri; Suleimanov, Valery F.; Revnivtsev, Mikhail G.; Kuulkers, Erik; Galloway, Duncan K.

    2014-12-01

    Neutron star (NS) masses and radii can be estimated from observations of photospheric radius-expansion X-ray bursts, provided the chemical composition of the photosphere, the spectral colour-correction factors in the observed luminosity range, and the emission area during the bursts are known. By analysing 246 X-ray bursts observed by the Rossi X-ray Timing Explorer from 11 low-mass X-ray binaries, we find a dependence between the persistent spectral properties and the time evolution of the blackbody normalization during the bursts. All NS atmosphere models predict that the colour-correction factor decreases in the early cooling phase when the luminosity first drops below the limiting Eddington value, leading to a characteristic pattern of variability in the measured blackbody normalization. However, the model predictions agree with the observations for most bursts occurring in hard, low-luminosity, island spectral states, but rarely during soft, high-luminosity, banana states. The observed behaviour may be attributed to the accretion flow, which influences cooling of the NS preferentially during the soft state bursts. This result implies that only the bursts occurring in the hard, low-luminosity spectral states can be reliably used for NS mass and radius determination.

  4. Decoding black hole X-ray variability using spectral-timing

    NASA Astrophysics Data System (ADS)

    Uttley, Phil

    2012-07-01

    X-ray variability is a ubiquitous feature of accreting black holes across the mass scale, from stellar mass to supermassive. The variability encodes information about the violent, unstable conditions in and around the accretion flow close to the black hole, but due to the complex and noise-like timing signatures it is difficult to decode this information. One very promising approach is to use X-ray spectral-timing - the combination of spectral and timing information using Fourier techniques - to measure the correlations and causal relationships between the different components in the X-ray spectrum, as a function of variability time-scale. Already these powerful techniques have revealed the first signatures of "X-ray reverberation" in AGN and X-ray binaries, offering the potential to map the emitting regions using light-travel time delays. Spectral-timing has also shown that much of the variability is driven by fluctuations in the "standard" accretion disc and not the corona or hot inner flow. I will briefly describe the spectral-timing approach and its achievements so far, before looking at the potential for spectral-timing with ASTROSAT.

  5. Dual-exposure technique for extending the dynamic range of x-ray flat panel detectors

    NASA Astrophysics Data System (ADS)

    Sisniega, A.; Abella, M.; Desco, M.; Vaquero, J. J.

    2014-01-01

    This work presents an approach to extend the dynamic range of x-ray flat panel detectors by combining two acquisitions of the same sample taken with two different x-ray photon flux levels and the same beam spectral configuration. In order to combine both datasets, the response of detector pixels was modelled in terms of mean and variance using a linear model. The model was extended to take into account the effect of pixel saturation. We estimated a joint probability density function (j-pdf) of the pixel values by assuming that each dataset follows an independent Gaussian distribution. This j-pdf was used for estimating the final pixel value of the high-dynamic-range dataset using a maximum likelihood method. The suitability of the pixel model for the representation of the detector signal was assessed using experimental data from a small-animal cone-beam micro-CT scanner equipped with a flat panel detector. The potential extension in dynamic range offered by our method was investigated for generic flat panel detectors using analytical expressions and simulations. The performance of the proposed dual-exposure approach in realistic imaging environments was compared with that of a regular single-exposure technique using experimental data from two different phantoms. Image quality was assessed in terms of signal-to-noise ratio, contrast, and analysis of profiles drawn on the images. The dynamic range, measured as the ratio between the exposure for saturation and the exposure equivalent to instrumentation noise, was increased from 76.9 to 166.7 when using our method. Dual-exposure results showed higher contrast-to-noise ratio and contrast resolution than the single-exposure acquisitions for the same x-ray dose. In addition, image artifacts were reduced in the combined dataset. This technique to extend the dynamic range of the detector without increasing the dose is particularly suited to image samples that contain both low and high attenuation regions.

  6. Facilities and techniques for x-ray diagnostic calibration in the 100-eV to 100-keV energy range

    SciTech Connect

    Gaines, J.L.; Wittmayer, F.J.

    1986-06-01

    The Lawrence Livermore National Laboratory (LLNL) has been a pioneer in the field of x-ray diagnostic calibration for more than 20 years. We have built steady state x-ray sources capable of supplying fluorescent lines of high spectral purity in the 100-eV to 100-keV energy range, and these sources have been used in the calibration of x-ray detectors, mirrors, crystals, filters, and film. This paper discusses our calibration philosophy and techniques, and describes some of our x-ray sources. Examples of actual calibration data are presented as well.

  7. THE OPTX PROJECT. III. X-RAY VERSUS OPTICAL SPECTRAL TYPE FOR ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Trouille, L.; Barger, A. J.; Cowie, L. L.; Yang, Y.; Mushotzky, R. F.

    2009-10-01

    We compare the optical spectral types with the X-ray spectral properties for a uniformly selected (sources with fluxes greater than the 3sigma level and above a flux limit of f {sub 2-8keV} > 3.5 x 10{sup -15} erg cm{sup -2} s{sup -1}), highly spectroscopically complete (>80% for f {sub 2-8keV} > 10{sup -14} erg cm{sup -2} s{sup -1} and >60% below) 2-8 keV X-ray sample observed in three Chandra fields (CLANS, CLASXS, and the CDF-N) that cover approx1.2 deg{sup 2}. For our sample of 645 spectroscopically observed sources, we confirm that there is significant overlap of the X-ray spectral properties, as determined by the effective photon indices, GAMMA{sub eff}, obtained from the ratios of the 0.5-2 keV to 2-8 keV counts, for the different optical spectral types. For example, broad-line active galactic nuclei (AGNs) are expected to be unobscured and hence X-ray soft (GAMMA{sub eff} >= 1.2), yet we find 20%+- 3% have GAMMA{sub eff} <1.2. Non-broad-line AGNs are expected to be obscured and hence X-ray hard (GAMMA{sub eff} < 1.2), yet we find 33% +- 4% have GAMMA{sub eff} >= 1.2. Thus, one cannot use the X-ray spectral classifications and the optical spectral classifications equivalently. Since it is not understood how X-ray and optical classifications relate to the obscuration of the central engine, we strongly advise against a mixed classification scheme, as it can only complicate the interpretation of X-ray AGN samples. We confirm the dependence of optical spectral type on X-ray luminosity, and for z < 1, we find a similar luminosity dependence of GAMMA{sub eff}. However, this dependence breaks down at higher redshifts due to the highly redshift-dependent nature of GAMMA{sub eff}. We therefore also caution that any classification scheme which depends on GAMMA{sub eff} is likely to suffer from serious redshift bias.

  8. XSPEC: An x ray spectral fitting package. Version 2 of the user's guide

    NASA Technical Reports Server (NTRS)

    Shafer, R. A.; Haberl, F.; Arnaud, K. A.; Tennant, A. F.; Barron, Chris (Editor)

    1991-01-01

    The user guide for XSPEC, a command driven, interactive, X-ray spectral fitting program is presented. It is designed to be completely detector independent so it can be used for any X-ray spectral instrument. An overview of the program commands and a walk through of an XSPEC session is presented. Individual commands and descriptions of the spectral models are given. For the more experienced user details of some of the programs associated with XSPEC, the command parser, and the addition of models to XSPEC are included. The PLT plotting package used by XSPEC is described together with the maximum likelihood option for users possessing X-ray spectra with small numbers of counts per bin. Details on the various files used by XSPEC and on the general file structure are also given.

  9. Spectral x-ray phase contrast imaging for single-shot retrieval of absorption, phase, and differential-phase imagery.

    PubMed

    Das, Mini; Liang, Zhihua

    2014-11-01

    In this Letter, we propose the first single-shot, noninterferometric x-ray imaging method for simultaneous retrieval of absorption, phase, and differential-phase imagery with quantitative accuracy. Our method utilizes a photon-counting spectral x-ray detector in conjunction with a simplified transport-of-intensity equation for coded-aperture phase-contrast imaging to efficiently solve the retrieval problem. This method can utilize an incoherent and polychromatic (clinical or laboratory) x-ray tube and can enable retrieval for a wide range and composition of material properties. The proposed method has been validated via computer simulations and is expected to significantly benefit applications that are sensitive to complexity of measurement, radiation dose and imaging time. PMID:25361350

  10. Spectrally resolving and scattering-compensated x-ray luminescence/fluorescence computed tomography

    NASA Astrophysics Data System (ADS)

    Cong, Wenxiang; Shen, Haiou; Wang, Ge

    2011-06-01

    The nanophosphors, or other similar materials, emit near-infrared (NIR) light upon x-ray excitation. They were designed as optical probes for in vivo visualization and analysis of molecular and cellular targets, pathways, and responses. Based on the previous work on x-ray fluorescence computed tomography (XFCT) and x-ray luminescence computed tomography (XLCT), here we propose a spectrally-resolving and scattering-compensated x-ray luminescence/fluorescence computed tomography (SXLCT or SXFCT) approach to quantify a spatial distribution of nanophosphors (other similar materials or chemical elements) within a biological object. In this paper, the x-ray scattering is taken into account in the reconstruction algorithm. The NIR scattering is described in the diffusion approximation model. Then, x-ray excitations are applied with different spectra, and NIR signals are measured in a spectrally resolving fashion. Finally, a linear relationship is established between the nanophosphor distribution and measured NIR data using the finite element method and inverted using the compressive sensing technique. The numerical simulation results demonstrate the feasibility and merits of the proposed approach.

  11. Compton scattering for spectroscopic detection of ultra-fast, high flux, broad energy range X-rays

    NASA Astrophysics Data System (ADS)

    Cipiccia, S.; Wiggins, S. M.; Maneuski, D.; Brunetti, E.; Vieux, G.; Yang, X.; Issac, R. C.; Welsh, G. H.; Anania, M.; Islam, M. R.; Ersfeld, B.; Montgomery, R.; Smith, G.; Hoek, M.; Hamilton, D. J.; Lemos, N. R. C.; Symes, D. R.; Rajeev, P. P.; Shea, V. O.; Dias, J. M.; Jaroszynski, D. A.

    2013-11-01

    Compton side-scattering has been used to simultaneously downshift the energy of keV to MeV energy range photons while attenuating their flux to enable single-shot, spectrally resolved, measurements of high flux X-ray sources to be undertaken. To demonstrate the technique a 1 mm thick pixelated cadmium telluride detector has been used to measure spectra of Compton side-scattered radiation from a Cobalt-60 laboratory source and a high flux, high peak brilliance X-ray source of betatron radiation from a laser-plasma wakefield accelerator.

  12. Compton scattering for spectroscopic detection of ultra-fast, high flux, broad energy range X-rays

    SciTech Connect

    Cipiccia, S.; Wiggins, S. M.; Brunetti, E.; Vieux, G.; Yang, X.; Welsh, G. H.; Anania, M.; Islam, M. R.; Ersfeld, B.; Jaroszynski, D. A.; Maneuski, D.; Montgomery, R.; Smith, G.; Hoek, M.; Hamilton, D. J.; Shea, V. O.; Issac, R. C.; Research Department of Physics, Mar Athanasius College, Kothamangalam 686666, Kerala ; Lemos, N. R. C.; Dias, J. M.; and others

    2013-11-15

    Compton side-scattering has been used to simultaneously downshift the energy of keV to MeV energy range photons while attenuating their flux to enable single-shot, spectrally resolved, measurements of high flux X-ray sources to be undertaken. To demonstrate the technique a 1 mm thick pixelated cadmium telluride detector has been used to measure spectra of Compton side-scattered radiation from a Cobalt-60 laboratory source and a high flux, high peak brilliance X-ray source of betatron radiation from a laser-plasma wakefield accelerator.

  13. Long-term wind-driven X-ray spectral variability of NGC 1365 with Swift

    NASA Astrophysics Data System (ADS)

    Connolly, S. D.; McHardy, I. M.; Dwelly, T.

    2014-06-01

    We present long-term (months-years) X-ray spectral variability of the Seyfert 1.8 galaxy NGC 1365 as observed by Swift, which provides well-sampled observations over a much longer time-scale (six years) and a much larger flux range than is afforded by other observatories. At very low luminosities, the spectrum is very soft, becoming rapidly harder as the luminosity increases and then, above a particular luminosity, softening again. At a given flux level, the scatter in hardness ratio is not very large, meaning that the spectral shape is largely determined by the luminosity. The spectra were therefore summed in luminosity bins and fitted with a variety of models. The best-fitting model consists of two power laws, one unabsorbed and another, more luminous, which is absorbed. In this model, we find a range of intrinsic 0.5-10.0 keV luminosities of approximately 1.1-3.5 erg s-1, and a very large range of absorbing columns, of approximately 1022-1024 cm-2. Interestingly, we find that the absorbing column decreases with increasing luminosity, but that this result is not due to changes in ionization. We suggest that these observations might be interpreted in terms of a wind model in which the launch radius varies as a function of ionizing flux and disc temperature and therefore moves out with increasing accretion rate, i.e. increasing X-ray luminosity. Thus, depending on the inclination angle of the disc relative to the observer, the absorbing column may decrease as the accretion rate goes up. The weaker, unabsorbed, component may be a scattered component from the wind.

  14. X-ray spectral parameters for a sample of 95 active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Vasylenko, A. A.; Zhdanov, V. I.; Fedorova, E. V.

    2015-12-01

    We present a broadband X-ray analysis of a new homogeneous sample of 95 active galactic nuclei (AGN) from the 22-month Swift/BAT all-sky survey. For this sample we treated jointly the X-ray spectra observed by XMM-Newton and INTEGRAL missions for the total spectral range of 0.5-250 keV. Photon index \\varGamma, relative reflection R, equivalent width of Fe K_{α} line EW_{FeK}, hydrogen column density NH, exponential cut-off energy Ec and intrinsic luminosity L_{corr} are determined for all objects of the sample. We investigated correlations \\varGamma-R, EW_{FeK}-L_{corr}, \\varGamma-Ec, EW_{FeK}-NH. Dependence "\\varGamma-R" for Seyfert 1/2 galaxies has been investigated separately. We found that the relative reflection parameter at low power-law indexes for Seyfert 2 galaxies is systematically higher than for Seyfert 1 ones. This can be related to an increasing contribution of the reflected radiation from the gas-dust torus. Our data show that there exists some anticorrelation between EW_{FeK} and L_{corr}, but it is not strong. We have not found statistically significant deviations from the AGN Unified Model.

  15. The X-ray Spectral Evolution of eta Carinae as Seen by ASCA

    NASA Technical Reports Server (NTRS)

    Corcoran, M. F.; Fredericks, A. C.; Petre, R.; Swank, J. H.; Drake, S. A.; White, Nicholas E. (Technical Monitor)

    2000-01-01

    Using data from the ASCA X-ray observatory, we examine the variations in the X-ray spectrum of the supermassive star nu Carinae with an unprecedented combination of spatial and spectral resolution. We include data taken during the recent X-ray eclipse in 1997-1998, after recovery from the eclipse, and during and after an X-ray flare. We show that the eclipse variation in the X-ray spectrum is apparently confined to a decrease in the emission measure of the source. We compare our results with a simple colliding wind binary model and find that the observed spectral variations are only consistent, with the binary model if there is significant high-temperature emission far from the star and/or a substantial change in the temperature distribution of the hot plasma. If contamination in the 2-10 keV band is important, the observed eclipse spectrum requires an absorbing column in excess of 10(exp 24)/sq cm for consistency with the binary model, which may indicate an increase in the first derivative of M from nu Carinae near the time of periastron passage. The flare spectra are consistent with the variability seen in nearly simultaneous RXTE observations and thus confirm that nu Carinae itself is the source of the flare emission. The variation in the spectrum during the flare seems confined to a change in the source emission measure. By comparing 2 observations obtained at the same phase in different X-ray cycles, we find that the current, X-ray brightness of the source is slightly higher than the brightness of the source during the last cycle perhaps indicative of a long-term increase in the first derivative of M, not associated with the X-ray cycle.

  16. Experimental measurements of selenium x-ray laser spectral line profiles

    SciTech Connect

    Koch, J.A.; MacGowan, B.J.; Da Silva, L.B.; Matthews, D.L.; London, R.A.; Lee, R.W.; Mrowka, S.; Underwood, J.H.; Batson, P.J.

    1993-03-01

    The authors discuss their recent measurements of the spectral width of the 206.38 {Angstrom} x-ray laser transition in Ne-like Se. These measurements used a high-resolution grating spectrometer and were performed over a wide range of laser amplifier lengths. The data have enabled them to extrapolate the intrinsic line width and to observe the effects of gain-narrowing and saturation on the line profile. They find an intrinsic width which is 1.4 times the Doppler width, they observe gain-narrowing in intermediate length amplifiers, and they observe no re-broadening in long, saturated amplifiers. These results suggest that collisional line-broadening has a significant effect on the line profile and saturation behavior of this laser.

  17. Spectral Atlas of X-ray Lines Emitted During Solar Flares Based on CHIANTI

    NASA Technical Reports Server (NTRS)

    Landi, E.; Phillips, K. J. H.

    2005-01-01

    A spectral atlas of X-ray lines in the wavelength range 7.47-18.97 Angstroms is presented, based on high-resolution spectra obtained during two M-class solar flares (on 1980 August 25 and 1985 July 2) with the Flat Crystal Spectrometer on board the Solar Maximum Mission. The physical properties of the flaring plasmas are derived as a function of time using strong, isolated lines. From these properties predicted spectra using the CHIANTI database have been obtained which were then compared with wavelengths and fluxes of lines in the observed spectra to establish line identifications. identifications for nearly all the observed lines in the resulting atlas are given, with some significant corrections to previous analysis of these flare spectra.

  18. Timing and Spectral Studies of the Peculiar X-ray Binary Circinus X-1

    SciTech Connect

    Saz Parkinson, Pablo M.

    2003-08-26

    Circinus X-1 (Cir X-1) is an X-ray binary displaying an array of phenomena which makes it unique in our Galaxy. Despite several decades of observation, controversy surrounds even the most basic facts about this system. It is generally classified as a Neutron Star (NS) Low Mass X-ray Binary (LMXB),though this classification is based primarily on the observation of Type I X-ray Bursts by EXOSAT in 1985. It is believed to be in a very eccentric {approx} 16.5 day orbit, displaying periodic outbursts in the radio and other frequency bands (including optical and IR) which reinforce the notion that this is in fact the orbital period. Cir X-1 lies in the plane of the Galaxy, where optical identification of the companion is made difficult due to dust obscuration. The companion is thought to be a low mass star, though a high mass companion has not currently been ruled out. In this work, the author analyzes recent observations of Cir X-1 made with the Unconventional Stellar Aspect (USA) experiment, as well as archival observations of Cir X-1 made by a variety of instruments, from as early as 1969. The fast (< 1 s) timing properties of Cir X-1 are studied by performing FFT analyses of the USA data. Quasi-Periodic Oscillations (QPOs) in the 1-50 Hz range are found and discussed in the context of recent correlations which question the leading models invoked for their generation. The energy dependence of the QPOs (rms increasing with energy) argues against them being generated in the disk and favors models in which the QPOs are related to a higher energy Comptonizing component. The power spectrum of Cir X-1 in its soft state is compared to that of Cygnus X-1 (Cyg X-1), the prototypical black hole candidate. Using scaling arguments the author argues that the mass of Cir X-1 could exceed significantly the canonical 1.4 M{circle_dot} mass of a neutron star, possibly partly explaining why this object appears so different to other neutron stars. The spectral evolution of Cir X-1 is studied by constructing both instrument-independent and model-independent color-color diagrams. Spectral fits are performed on all USA observations and physical parameters are derived. Cir X-1 periodically evolves from a high/soft state to a low/hard state within each orbital cycle. The spectral fits obtained indicate that a two-component model provides an appropriate description of the Cir X-1 spectrum with one component representing the emission from a multicolor blackbody accretion disk while the other component represents the higher energy Comptonized emission probably coming from a boundary layer on the surface of the neutron star. To study the long-term X-ray variability of Cir X-1 the author analyzes archival data from instruments going back to 1969 (Vela 5 satellite), up to more recent RXTE ASM data (for the last 6.5 years). The author uses various period finding techniques such as Lomb-Scargle periodograms and Phase Dispersion Minimization. Cir X-1 shows large variations in overall flux over the course of the last 30 years, with the brightest epoch corresponding to the recent RXTE/USA era. The author derives an X-ray ephemeris based on these long term observations showing that the period of Cir X-1 is rapidly decreasing (P/P < 3000 yrs), possibly implying a very young age for the system.

  19. Relationship between X-ray spectral index and X-ray Eddington ratio for Mrk 335 and Ark 564

    NASA Astrophysics Data System (ADS)

    Sarma, R.; Tripathi, S.; Misra, R.; Dewangan, G.; Pathak, A.; Sarma, J. K.

    2015-04-01

    We present a comprehensive flux-resolved spectral analysis of the bright narrow-line Seyfert 1 AGNs, Mrk 335 and Ark 564 using observations by XMM-Newton satellite. The mean and the flux-resolved spectra are fitted by an empirical model consisting of two Comptonization components, one for the low-energy soft excess and the other for the high-energy power law. A broad iron line and a couple of low-energy edges are required to explain the spectra. For Mrk 335, the 0.3-10 keV luminosity relative to the Eddington value, LX/LEdd, varied from 0.002 to 0.06. The index variation can be empirically described as ? = 0.6 log10 LX/LEdd + 3.0 for 0.005 < LX/LEdd < 0.04. At LX/LEdd 0.04 the spectral index changes and then continues to follow ? = 0.6 log10 LX/LEdd + 2.7, i.e. on a parallel track. We confirm that the result is independent of the specific spectral model used by fitting the data in the 3-10 keV band by only a power law and an iron line. For Ark 564, the index variation can be empirically described as ? = 0.2 log10 LX/LEdd + 2.7 with a significantly large scatter as compared to Mrk 335. Our results indicate that for Mrk 335, there may be accretion disc geometry changes which lead to different parallel tracks. These changes could be related to structural changes in the corona or enhanced reflection at high flux levels. There does not seem to be any homogeneous or universal relationship for the X-ray index and luminosity for different AGNs or even for the same AGN.

  20. Spectral variability of Cyg X-3. [X ray sources

    NASA Technical Reports Server (NTRS)

    Serlemitsos, P. J.; Boldt, E. A.; Holt, S. S.; Rothschild, R. E.; Saba, J. L. R.

    1975-01-01

    The 1.7-40 keV spectra of Cyg X-3 obtained about a year apart, using the same rocket payload, show large spectral differences. The two observations suggest that while the luminosity of this source remains roughly the same, its spectrum can vary from a featureless blackbody distribution to a flat spectrum which includes strong iron line emission at approximately 6.7 keV. The flux in the line corresponds to an equivalent continuum width of 1.2 keV.

  1. An XMM-Newton spectral survey of 12 ?m selected galaxies - I. X-ray data

    NASA Astrophysics Data System (ADS)

    Brightman, Murray; Nandra, Kirpal

    2011-05-01

    We present an X-ray spectral analysis of 126 galaxies of the 12 ?m galaxy sample. By studying this sample at X-ray wavelengths, we aim to determine the intrinsic power, continuum shape and obscuration level in these sources. We improve upon previous works by the use of superior data in the form of higher signal-to-noise ratio spectra, finer spectral resolution and a broader bandpass from XMM-Newton. We pay particular attention to Compton thick active galactic nucleus (AGN) with the help of new spectral fitting models that we have produced, which are based on Monte Carlo simulations of X-ray radiative transfer, using both a spherical and torus geometry, and taking into account Compton scattering and iron fluorescence. We use this data to show that with a torus geometry, unobscured sightlines can achieve a maximum equivalent width of the Fe K? line of 150 eV, originally shown by Ghisellini et al. In order for this to be exceeded, the line of sight must be obscured with NH > 1023 cm-2, as we show for one case, NGC 3690. We also calculate flux suppression factors from the simulated data, the main conclusion from which is that for NH? 1025 cm-2, the X-ray flux is suppressed by a factor of at least 10 in all X-ray bands and at all redshifts, revealing the biases present against these extremely heavily obscured systems inherent in all X-ray surveys. Furthermore, we confirm previous results from Murphy & Yaqoob that show that the reflection fraction determined from slab geometries is underestimated with respect to toroidal geometries. For the 12 ?m selected galaxies, we investigate the distribution of X-ray power-law indices, finding that the mean (= 1.90+0.05-0.07 and ??= 0.31+0.05-0.05) is consistent with previous works, and that the distribution of ? for obscured and unobscured sources is consistent with the source populations being the same, in general support of unification schemes. We determine a Compton thick fraction for the X-ray AGN in our sample to be 18 5 per cent which is higher than the hard X-ray (>10 keV) selected samples. Finally we find that the obscured fraction for our sample is a strong function of X-ray luminosity, peaking at a luminosity of 1042-43 erg s-1.

  2. The Impact of Accurate Extinction Measurements for X-Ray Spectral Models

    NASA Astrophysics Data System (ADS)

    Smith, Randall K.; Valencic, Lynne A.; Corrales, Lia

    2016-02-01

    Interstellar extinction includes both absorption and scattering of photons from interstellar gas and dust grains, and it has the effect of altering a source's spectrum and its total observed intensity. However, while multiple absorption models exist, there are no useful scattering models in standard X-ray spectrum fitting tools, such as XSPEC. Nonetheless, X-ray halos, created by scattering from dust grains, are detected around even moderately absorbed sources, and the impact on an observed source spectrum can be significant, if modest, compared to direct absorption. By convolving the scattering cross section with dust models, we have created a spectral model as a function of energy, type of dust, and extraction region that can be used with models of direct absorption. This will ensure that the extinction model is consistent and enable direct connections to be made between a source's X-ray spectral fits and its UV/optical extinction.

  3. Spectral encoding method for measuring the relative arrival time between x-ray/optical pulses

    SciTech Connect

    Bionta, M. R.; Hartmann, N.; Weaver, M.; French, D.; Glownia, J. M.; Bostedt, C.; Chollet, M.; Ding, Y.; Fritz, D. M.; Fry, A. R.; Krzywinski, J.; Lemke, H. T.; Messerschmidt, M.; Schorb, S.; Zhu, D.; White, W. E.; Nicholson, D. J.; Cryan, J. P.; Baker, K.; Kane, D. J.; and others

    2014-08-15

    The advent of few femtosecond x-ray light sources brings promise of x-ray/optical pump-probe experiments that can measure chemical and structural changes in the 10100 fs time regime. Widely distributed timing systems used at x-ray Free-Electron Laser facilities are typically limited to above 50 fs fwhm jitter in active x-ray/optical synchronization. The approach of single-shot timing measurements is used to sort results in the event processing stage. This has seen wide use to accommodate the insufficient precision of active stabilization schemes. In this article, we review the current technique for measure-and-sort at the Linac Coherent Light Source at the SLAC National Accelerator Laboratory. The relative arrival time between an x-ray pulse and an optical pulse is measured near the experimental interaction region as a spectrally encoded cross-correlation signal. The cross-correlation provides a time-stamp for filter-and-sort algorithms used for real-time sorting. Sub-10 fs rms resolution is common in this technique, placing timing precision at the same scale as the duration of the shortest achievable x-ray pulses.

  4. Spectral encoding method for measuring the relative arrival time between x-ray/optical pulses

    NASA Astrophysics Data System (ADS)

    Bionta, M. R.; Hartmann, N.; Weaver, M.; French, D.; Nicholson, D. J.; Cryan, J. P.; Glownia, J. M.; Baker, K.; Bostedt, C.; Chollet, M.; Ding, Y.; Fritz, D. M.; Fry, A. R.; Kane, D. J.; Krzywinski, J.; Lemke, H. T.; Messerschmidt, M.; Schorb, S.; Zhu, D.; White, W. E.; Coffee, R. N.

    2014-08-01

    The advent of few femtosecond x-ray light sources brings promise of x-ray/optical pump-probe experiments that can measure chemical and structural changes in the 10-100 fs time regime. Widely distributed timing systems used at x-ray Free-Electron Laser facilities are typically limited to above 50 fs fwhm jitter in active x-ray/optical synchronization. The approach of single-shot timing measurements is used to sort results in the event processing stage. This has seen wide use to accommodate the insufficient precision of active stabilization schemes. In this article, we review the current technique for "measure-and-sort" at the Linac Coherent Light Source at the SLAC National Accelerator Laboratory. The relative arrival time between an x-ray pulse and an optical pulse is measured near the experimental interaction region as a spectrally encoded cross-correlation signal. The cross-correlation provides a time-stamp for filter-and-sort algorithms used for real-time sorting. Sub-10 fs rms resolution is common in this technique, placing timing precision at the same scale as the duration of the shortest achievable x-ray pulses.

  5. Spectral encoding method for measuring the relative arrival time between x-ray/optical pulses.

    PubMed

    Bionta, M R; Hartmann, N; Weaver, M; French, D; Nicholson, D J; Cryan, J P; Glownia, J M; Baker, K; Bostedt, C; Chollet, M; Ding, Y; Fritz, D M; Fry, A R; Kane, D J; Krzywinski, J; Lemke, H T; Messerschmidt, M; Schorb, S; Zhu, D; White, W E; Coffee, R N

    2014-08-01

    The advent of few femtosecond x-ray light sources brings promise of x-ray/optical pump-probe experiments that can measure chemical and structural changes in the 10-100 fs time regime. Widely distributed timing systems used at x-ray Free-Electron Laser facilities are typically limited to above 50 fs fwhm jitter in active x-ray/optical synchronization. The approach of single-shot timing measurements is used to sort results in the event processing stage. This has seen wide use to accommodate the insufficient precision of active stabilization schemes. In this article, we review the current technique for "measure-and-sort" at the Linac Coherent Light Source at the SLAC National Accelerator Laboratory. The relative arrival time between an x-ray pulse and an optical pulse is measured near the experimental interaction region as a spectrally encoded cross-correlation signal. The cross-correlation provides a time-stamp for filter-and-sort algorithms used for real-time sorting. Sub-10 fs rms resolution is common in this technique, placing timing precision at the same scale as the duration of the shortest achievable x-ray pulses. PMID:25173255

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  7. Photoelectron range limitations to the spatial resolution for x-rays in gas proportional chambers

    SciTech Connect

    Smith, G.C.; Fischer, J.; Radeka, V.

    1983-11-01

    Measurements have been made, for x-ray energies from a few keV to 18 keV, of the limiting spatial resolution caused by the finite range of the photoelectron, or electrons, created when an x-ray is absorbed in the gas of a proportional chamber. In hydrocarbon gases such as methane and ethane, where the photoelectron receives the bulk of the x-ray energy, the limiting spatial resolution is found to vary as a power law of x-ray energy. In argon and xenon, at an x-ray energy approximately twice that of the A/sub K/ edge and the Xe/sub L/ edge respectively, the measured limiting resolution is better than expected from an equivalent power law behavior.

  8. X-Ray Spectral Variability Signatures of Flares in BL Lac Objects

    NASA Technical Reports Server (NTRS)

    Boettcher, Markus; Chiang, James; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We are presenting a detailed parameter study of the time-dependent electron injection and kinematics and the self-consistent radiation transport in jets of intermediate and low-frequency peaked BL Lac objects. Using a time-dependent, combined synchrotron-self-Compton and external-Compton jet model, we study the influence of variations of several essential model parameters, such as the electron injection compactness, the relative contribution of synchrotron to external soft photons to the soft photon compactness, the electron- injection spectral index, and the details of the time profiles of the electron injection episodes giving rise to flaring activity. In the analysis of our results, we focus on the expected X-ray spectral variability signatures in a region of parameter space particularly well suited to reproduce the broadband spectral energy distributions of intermediate and low-frequency peaked BL Lac objects. We demonstrate that SSC- and external-Compton dominated models for the gamma-ray emission from blazars are producing significantly different signatures in the X-ray variability, in particular in the soft X-ray light curves and the spectral hysteresis at soft X-ray energies, which can be used as a powerful diagnostic to unveil the nature of the high-energy emission from BL Lac objects.

  9. An X-Ray Free-Electron Laser Oscillator for Record High Spectral Purity and Average Brightness (Progress and Prospects for X-ray Free Electron Lasers)

    SciTech Connect

    Kim, Kwang-Je

    2009-06-24

    With the success of the LCLS at SLAC, synchrotron radiation community is entering the era of x-ray free-electron lasers (FELs) with an enormous jump in brightness and coherence over that possible with third-generation x-ray sources. The LCLS is a single-pass, high-gain device producing quasi-coherent x-rays known as self-amplified spontaneous emission. Hard x-ray FELs are also feasible in an oscillator (XFELO) configuration, in which an x-ray pulse is trapped a low-loss optical cavity consisting of diamond crystals, permitting build-up in the intensity and coherence over several hundred passes. An XFELO produces ultrahigh spectral purity and brightness-average brightness several orders of magnitude higher than, and peak brightness comparable to, self-amplified spontaneous emission devices; opening up new scientific opportunities as well as drastically improving and complementing experimental techniques developed at third-generation x-ray facilities. We discuss unique R&D issues in accelerator and x-ray optics and encouraging progress to date.

  10. The X-ray spectral variability of the BL Lacertae type object PKS 2155-304

    NASA Technical Reports Server (NTRS)

    Sembay, S.; Warwick, R. S.; Urry, C. M.; Sokoloski, J.; George, I. M.; Makino, F.; Ohashi, T.; Tashiro, M.

    1993-01-01

    We present a detailed study of the hard X-ray properties of the BL Lacertae object PKS 2155-304 based on measurements made in 1988 and 1989 with the Large Area Counter (LAC) on board the Ginga satellite. The source exhibited a high degree of variability with a dynamic range of a factor 7 in the 2-6 keV band. The fastest amplitude variation was a factor 2 decline in the intensity in this band within 4 hours. The spectrum is characterized by a break which occurs at about 4 keV. Spectral fits to the data integrated in 6400 s time bins reveal that, in common with previous observations of BL Lacertae objects, the spectral slope is generally anticorrelated with intensity in the sense that the spectrum hardens as the intensity increases. However, the tracks of sequential points in the index-intensity plane are occasionally seen to differ during the rise and decay stages of individual flares. Furthermore, during one, or possibly two, flaring episodes the spectral index is observed to correlate with intensity variations.

  11. New consistency tests for high-accuracy measurements of X-ray mass attenuation coefficients by the X-ray extended-range technique

    SciTech Connect

    Chantler, C.T.; Islam, M.T.; Rae, N.A.; Tran, C.Q.; Glover, J.L.; Barnea, Z.

    2012-09-25

    An extension of the X-ray extended-range technique is described for measuring X-ray mass attenuation coefficients by introducing absolute measurement of a number of foils - the multiple independent foil technique. Illustrating the technique with the results of measurements for gold in the 38-50 keV energy range, it is shown that its use enables selection of the most uniform and well defined of available foils, leading to more accurate measurements; it allows one to test the consistency of independently measured absolute values of the mass attenuation coefficient with those obtained by the thickness transfer method; and it tests the linearity of the response of the counter and counting chain throughout the range of X-ray intensities encountered in a given experiment. In light of the results for gold, the strategy to be ideally employed in measuring absolute X-ray mass attenuation coefficients, X-ray absorption fine structure and related quantities is discussed.

  12. Testing the Pairs-Reflection Model with X-Ray Spectral Variability and X-Ray Properties of Complete Samples of Radio-Selected BL Lacertae Objects

    NASA Technical Reports Server (NTRS)

    Urry, C. Megan

    1997-01-01

    This grant was awarded to Dr. C. Megan Urry of the Space Telescope Science Institute in response to two successful ADP proposals to use archival Ginga and Rosat X-ray data for 'Testing the Pairs-Reflection model with X-Ray Spectral Variability' (in collaboration with Paola Grandi, now at the University of Rome) and 'X-Ray Properties of Complete Samples of Radio-Selected BL Lacertae Objects' (in collaboration with then-graduate student Rita Sambruna, now a post-doc at Goddard Space Flight Center). In addition, post-docs Joseph Pesce and Elena Pian, and graduate student Matthew O'Dowd, have worked on several aspects of these projects. The grant was originally awarded on 3/01/94; this report covers the full period, through May 1997. We have completed our project on the X-ray properties of radio-selected BL Lacs.

  13. C IV EMISSION AND THE ULTRAVIOLET THROUGH X-RAY SPECTRAL ENERGY DISTRIBUTION OF RADIO-QUIET QUASARS

    SciTech Connect

    Kruczek, Nicholas E.; Richards, Gordon T.; Deo, Rajesh P.; Krawczyk, Coleman M.; Gallagher, S. C.; Hall, Patrick B.; Hewett, Paul C.; Leighly, Karen M.; Proga, Daniel

    2011-10-15

    In the rest-frame ultraviolet (UV), two of the parameters that best characterize the range of emission-line properties in quasar broad emission-line regions are the equivalent width and the blueshift of the C IV {lambda}1549 line relative to the quasar rest frame. We explore the connection between these emission-line properties and the UV through X-ray spectral energy distribution (SED) for radio-quiet (RQ) quasars. Our sample consists of a heterogeneous compilation of 406 quasars from the Sloan Digital Sky Survey (at z > 1.54) and Palomar-Green survey (at z < 0.4) that have well-measured C IV emission-line and X-ray properties (including 164 objects with measured {Gamma}). We find that RQ quasars with both strong C IV emission and small C IV blueshifts can be classified as 'hard-spectrum' sources that are (relatively) strong in the X-ray as compared to the UV. On the other hand, RQ quasars with both weak C IV emission and large C IV blueshifts are instead 'soft-spectrum' sources that are (relatively) weak in the X-ray as compared to the UV. This work helps to further bridge optical/soft X-ray 'eigenvector 1' relationships to the UV and hard X-ray. Based on these findings, we argue that future work should consider systematic errors in bolometric corrections (and thus accretion rates) that are derived from a single mean SED. Detailed analysis of the C IV emission line may allow for SED-dependent corrections to these quantities.

  14. Parameterized algorithms for quantitative differentials in spectrally equivalent medical diagnostic x-ray beams

    SciTech Connect

    Okunade, Akintunde Akangbe

    2005-06-15

    Qualitative and quantitative equivalence of spectra transmitted by two different elemental filters require a good match in terms of shape and size over the entire energy range of 0-150 keV used in medical diagnostic radiology. However, the photoelectric absorptions and Compton scattering involved in the interaction of x rays with matter at these relatively low photon energies differ in a nonuniform manner with energy and atomic number. By careful choice of thicknesses for filter materials with an atomic number between 12 and 39, when compared with aluminum, it is possible to obtain transmitted beams of the same shape (quality) but not of the same size (quantity). In this paper, calculations have been carried out for the matching of the shapes and sizes of beams transmitted through specified thicknesses of aluminium filter and spectrally equivalent thicknesses of other filter materials (different from aluminium) using FORTRAN source codes traceable to the American Association of Physics in Medicine (AAPM), College Park, MD, USA. Parametrized algorithms for the evaluation of quantitative differentials (deficit or surplus) in radiation output (namely, photon fluence, exposure, kerma, energy imparted, absorbed dose, and effective dose) from these transmitted spectrally equivalent beams were developed. These differentials range between 1%, and 4% at 1 mm Al filtration and between 8%, and 25% for filtration of 6 mm Al for different filter materials in comparison with aluminum. Also developed were models for factors for converting measures of photon fluence, exposure-area product, (EAP), and kerma-area product (KAP) to risk related quantities such as energy imparted, absorbed dose, and effective dose from the spectrally equivalent beams. The thicknesses of other filter materials that are spectrally equivalent to given thicknesses of aluminum filter were characterized using polynomial functions. The fact that the use of equivalent spectra in radiological practice can provide means of ranking the differentials in radiographic image quality and stochastic risk is discussed.

  15. Spatial and spectral features of soft diffuse X ray background seen by the Einstein observatory

    NASA Technical Reports Server (NTRS)

    Micela, G.; Harnden, F. R.; Rosner, R., Jr.; Sciortino, S.; Vaiana, G. S.

    1989-01-01

    A survey of the diffuse soft X-ray background as seen directly by the Einstein Observatory Imaging Proportional Counter (IPC) is presented. A source free region of the detector 1 by 1 degree field is used. The background in the 0.16 to 3.5 keV spectral region is viewed. The data covers roughly 5 percent of the sky, with some bias in coverage towards the galactic plane. The moderate energy resolution of the IPC enables the characterization and the production of maps of the background as a function of energy within the Einstein passband. The results are compared with previous observations of the diffuse X-ray background. The implications for galactic structure and for the soft component of the extragalactic X-ray background are discussed.

  16. TEMPORAL AND SPATIAL ANALYSES OF SPECTRAL INDICES OF NONTHERMAL EMISSIONS DERIVED FROM HARD X-RAYS AND MICROWAVES

    SciTech Connect

    Asai, Ayumi; Kiyohara, Junko; Takasaki, Hiroyuki; Narukage, Noriyuki; Yokoyama, Takaaki; Masuda, Satoshi; Shimojo, Masumi; Nakajima, Hiroshi

    2013-02-15

    We studied electron spectral indices of nonthermal emissions seen in hard X-rays (HXRs) and microwaves. We analyzed 12 flares observed by the Hard X-Ray Telescope aboard Yohkoh, Nobeyama Radio Polarimeters, and the Nobeyama Radioheliograph (NoRH), and compared the spectral indices derived from total fluxes of HXRs and microwaves. Except for four events, which have very soft HXR spectra suffering from the thermal component, these flares show a gap {Delta}{delta} between the electron spectral indices derived from HXRs {delta} {sub X} and those from microwaves {delta}{sub {mu}} ({Delta}{delta} = {delta} {sub X} - {delta}{sub {mu}}) of about 1.6. Furthermore, from the start to the peak times of the HXR bursts, the time profiles of the HXR spectral index {delta} {sub X} evolve synchronously with those of the microwave spectral index {delta}{sub {mu}}, keeping the constant gap. We also examined the spatially resolved distribution of the microwave spectral index by using NoRH data. The microwave spectral index {delta}{sub {mu}} tends to be larger, which means a softer spectrum, at HXR footpoint sources with stronger magnetic field than that at the loop tops. These results suggest that the electron spectra are bent at around several hundreds of keV, and become harder at the higher energy range that contributes the microwave gyrosynchrotron emission.

  17. A HARD X-RAY POWER-LAW SPECTRAL CUTOFF IN CENTAURUS X-4

    SciTech Connect

    Chakrabarty, Deepto; Nowak, Michael A.; Tomsick, John A.; Boggs, Steven E.; Craig, William W.; Grefenstette, Brian W.; Fürst, Felix; Harrison, Fiona A.; Rana, Vikram; Psaltis, Dimitrios; Bachetti, Matteo; Barret, Didier; Christensen, Finn E.; Hailey, Charles J.; Kaspi, Victoria M.; Miller, Jon M.; Stern, Daniel; Wik, Daniel R.; Zhang, William W.; Wilms, Jörn

    2014-12-20

    The low-mass X-ray binary (LMXB) Cen X-4 is the brightest and closest (<1.2 kpc) quiescent neutron star transient. Previous 0.5-10 keV X-ray observations of Cen X-4 in quiescence identified two spectral components: soft thermal emission from the neutron star atmosphere and a hard power-law tail of unknown origin. We report here on a simultaneous observation of Cen X-4 with NuSTAR (3-79 keV) and XMM-Newton (0.3-10 keV) in 2013 January, providing the first sensitive hard X-ray spectrum of a quiescent neutron star transient. The 0.3-79 keV luminosity was 1.1×10{sup 33} D{sub kpc}{sup 2} erg s{sup –1}, with ≅60% in the thermal component. We clearly detect a cutoff of the hard spectral tail above 10 keV, the first time such a feature has been detected in this source class. We show that thermal Comptonization and synchrotron shock origins for the hard X-ray emission are ruled out on physical grounds. However, the hard X-ray spectrum is well fit by a thermal bremsstrahlung model with kT{sub e} = 18 keV, which can be understood as arising either in a hot layer above the neutron star atmosphere or in a radiatively inefficient accretion flow. The power-law cutoff energy may be set by the degree of Compton cooling of the bremsstrahlung electrons by thermal seed photons from the neutron star surface. Lower thermal luminosities should lead to higher (possibly undetectable) cutoff energies. We compare Cen X-4's behavior with PSR J1023+0038, IGR J18245–2452, and XSS J12270–4859, which have shown transitions between LMXB and radio pulsar modes at a similar X-ray luminosity.

  18. Morphology and spectral characteristics of the X-ray emission of M33

    NASA Technical Reports Server (NTRS)

    Trinchieri, G.; Fabbiano, G.; Peres, G.

    1988-01-01

    A previous analysis of the X-ray data on M33 has been extended to include a detailed study of the morpholgoy and spectral characteristics of the X-ray emission, and the results are reported. A low surface brightness, extended emission in the plane of the galaxy is detected. The X-ray luminosity of this component, about 10 to the 38th egs/s, is comparable to the total luminosity of the bright sources observed in the same region. Its radial distribution is similar to that of the blue light. The spectrum of the extended emission shows two distinct components: a hard one, with a temperature above 3 keV and a soft one with a temperature below 1 keV. The X-ray spectrum of the nuclear source, which is inconsistent with any of the known spectra of X-ray binary sources, can be fitted with either a low-temperature thermal emission or a steep power law model.

  19. X-ray spectral variability of low ionization nuclear emission line regions (LINERs)

    NASA Astrophysics Data System (ADS)

    Hernndez-Garca, L.; Gonzlez-Martn, O.; Masegosa, J.; Mrquez, I.

    2015-05-01

    Although variability is a general property of AGN, and in LINERs variations in timescales of months/years have been found for some objects, it is not clear how these changes occur. The main purpose of this work is to investigate the X-ray variability in LINERs, including the main driver of such variations. We use the 18 LINERs in the Palomar sample with data at different epochs available in Chandra and/or XMM-Newton archives. All the spectra for the same object are simultaneously fitted to study long term variations. The nature of the variability pattern was studied allowing the different parameters to vary during the spectral fit. Whenever possible, short term variations and UV variability are studied. Short term variations are not found at X-rays. Taking into account the data at X-rays (seven out of 12 objects) and UV (five out of six), ten out of 13 LINERs show long term variations. The main driver of the X-ray variations is related to changes in the nuclear power, while changes on absorptions are found only in one case. According to their BH masses, accretion rates and variability timescales, LINERs behave as more powerful AGN at X-rays. However, we conclude that a different accretion mechanism (compared to more powerful AGN) may be present, based on the anticorrelation between ? and the Eddington ratio.

  20. New constraints on the X-ray spectral properties of type 1 active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Scott, A. E.; Stewart, G. C.; Mateos, S.; Alexander, D. M.; Hutton, S.; Ward, M. J.

    2011-10-01

    We present a detailed characterization of the X-ray spectral properties of 761 type 1 active galactic nuclei (AGN), selected from a cross-correlation of the SDSS DR5 quasar catalogue and the incremental version of the second XMM-Newton serendipitous X-ray source catalogue 2XMMi-DR2. The X-ray spectrum of each source has been fitted with models based on a simple power law to which additional cold absorption and/or soft-excess features have been added if an F-test at 99 per cent significance required them. The distribution of best-fitting photon indices, Γ, has been fitted with a Gaussian with mean <Γ>= 1.99 ± 0.01 and dispersion σ<Γ>= 0.30 ± 0.01; however, this does not provide a good representation of the distribution due to sources with very flat or steep Γ values. A highly significant trend for decreasing Γ values with increasing 2-10 keV luminosity, LX, has been seen but only a weak trend with redshift has been found. Intrinsic cold absorption has been detected in ˜4 per cent of the sample and soft-excess emission has been detected in ˜8 per cent. These values are lower limits due to the detectability being limited by the quality of the spectra and we suggest that the intrinsic values may be as high as ˜25 and ˜80 per cent, respectively. The levels of rest-frame absorption are higher than expected for type 1 objects (NH= 1021-1023 cm-2) and the fraction of absorbed sources and the NH values were not seen to vary with LX or z. The average blackbody temperature used to model the soft excesses is = 0.17 ± 0.09 keV. This temperature has been found to correlate with LX but not the blackbody luminosity or the black hole mass which do correlate with each other. A strong correlation has been found between the luminosities in the blackbody and power-law components, suggesting that a similar fraction is reprocessed from the blackbody to the power-law component for the entire luminosity range of objects. A positive correlation between Γ and the X-ray derived Eddington ratio has been found for the sources whose mass was determined using the Hβ line, but a negative correlation has been found where the C IV line was used. No correlation has been found where the Mg II line was used. No significant correlations have been found between the blackbody temperature, luminosity or black hole mass with Eddington ratio, despite a link between the power law and blackbody production being indicated. The sample includes 552 confirmed radio-quiet quasars (RQQ) and 75 confirmed radio-loud quasars (RLQ). The RLQ have been found to have higher LX values than their RQQ counterparts, suggesting an additional X-ray component, perhaps related to a jet, is present in these sources. This component may also be the cause of the flatter Γ values seen in RLQ.

  1. X-Ray Spectral and Timing Behavior of Scorpius X-1. Spectral Hardening during the Flaring Branch

    NASA Astrophysics Data System (ADS)

    Titarchuk, Lev; Seifina, Elena; Shrader, Chris

    2014-07-01

    We present an analysis of the spectral and timing properties of X-ray emission from the Z-source Sco X-1 during its evolution between the horizontal (HB) and flaring (FB) branches observed with the Rossi X-ray Timing Explorer during the 1996-2002 period. We find that the broadband (3-250 keV) energy spectra during all spectral states can be adequately reproduced by a model, consisting of two Comptonized components and an iron line. We suggest that the seed photons of kT s1 <~ 0.7 keV coming from the disk and of temperature kT s2 <~ 1.8 keV coming from the neutron star (NS) are each upscattered by hot electrons of a "Compton cloud" (hereafter the Comptb1 and Comptb2 components, respectively, which are associated with the similarly subscripted parameters). The photon power-law index ?2 is almost constant (?2 ~ 2) for all spectral states. In turn, ?1 demonstrates a two-phase behavior with the spectral state: ?1 is quasi-constant at the level ?1 ~ 2 for the HB-NB and ?1 is less than 2, namely in the range of 1.3 < ?1 < 2, when the source traces the FB. We also detect a decrease kT s2 from 1.8 keV to 0.7 keV during the FB. We interpret this apparent quasi-stability of the indices during the HB-NB in the framework of the model in which the spectrum is determined by the Comptonized thermal components. This effect established for the Comptonized spectral components of the Z-source Sco X-1 is similar to what was previously found in the atoll sources 4U 1728-34, GX 3+1 and 4U 1820-30 and the Z-source GX 340+0 through all spectral states. However, we interpret the index reduction phase detected during the FB in Sco X-1 within the framework of a model in which the spectrum at the FB is determined by high radiation pressure from the NS surface.

  2. X-ray spectral and timing behavior of Scorpius X-1. Spectral hardening during the flaring branch

    SciTech Connect

    Titarchuk, Lev; Seifina, Elena

    2014-07-10

    We present an analysis of the spectral and timing properties of X-ray emission from the Z-source Sco X-1 during its evolution between the horizontal (HB) and flaring (FB) branches observed with the Rossi X-ray Timing Explorer during the 1996-2002 period. We find that the broadband (3-250 keV) energy spectra during all spectral states can be adequately reproduced by a model, consisting of two Comptonized components and an iron line. We suggest that the seed photons of kT{sub s1} ? 0.7 keV coming from the disk and of temperature kT{sub s2} ? 1.8 keV coming from the neutron star (NS) are each upscattered by hot electrons of a 'Compton cloud' (hereafter the Comptb1 and Comptb2 components, respectively, which are associated with the similarly subscripted parameters). The photon power-law index ?{sub 2} is almost constant (?{sub 2} ? 2) for all spectral states. In turn, ?{sub 1} demonstrates a two-phase behavior with the spectral state: ?{sub 1} is quasi-constant at the level ?{sub 1} ? 2 for the HBNB and ?{sub 1} is less than 2, namely in the range of 1.3 < ?{sub 1} < 2, when the source traces the FB. We also detect a decrease kT{sub s2} from 1.8 keV to 0.7 keV during the FB. We interpret this apparent quasi-stability of the indices during the HBNB in the framework of the model in which the spectrum is determined by the Comptonized thermal components. This effect established for the Comptonized spectral components of the Z-source Sco X-1 is similar to what was previously found in the atoll sources 4U 1728-34, GX 3+1 and 4U 1820-30 and the Z-source GX 340+0 through all spectral states. However, we interpret the index reduction phase detected during the FB in Sco X-1 within the framework of a model in which the spectrum at the FB is determined by high radiation pressure from the NS surface.

  3. X-ray spectral properties of active galactic nuclei in the Chandra Deep Field South

    NASA Astrophysics Data System (ADS)

    Tozzi, P.; Gilli, R.; Mainieri, V.; Norman, C.; Risaliti, G.; Rosati, P.; Bergeron, J.; Borgani, S.; Giacconi, R.; Hasinger, G.; Nonino, M.; Streblyanska, A.; Szokoly, G.; Wang, J. X.; Zheng, W.

    2006-05-01

    We present a detailed X-ray spectral analysis of the sources in the 1Ms catalog of the Chandra Deep Field South (CDFS) taking advantage of optical spectroscopy and photometric redshifts for 321 extragalactic sources out of the total sample of 347 sources. As a default spectral model, we adopt a power law with slope Γ with an intrinsic redshifted absorption N_H, a fixed Galactic absorption and an unresolved Fe emission line. For 82 X-ray bright sources, we are able to perform the X-ray spectral analysis leaving both Γ and NH free. The weighted mean value for the slope of the power law is < Γ > ≃ 1.75 ± 0.02, and the distribution of best fit values shows an intrinsic dispersion of σ_int ≃ 0.30. We do not find hints of a correlation between the spectral index Γ and the intrinsic absorption column density N_H. We then investigate the absorption distribution for the whole sample, deriving the NH values in faint sources by fixing Γ = 1.8. We also allow for the presence of a scattered component at soft energies with the same slope of the main power law, and for a pure reflection spectrum typical of Compton-thick AGN. We detect the presence of a scattered soft component in 8 sources; we also identify 14 sources showing a reflection-dominated spectrum. The latter are referred to as Compton-thick AGN candidates. By correcting for both incompleteness and sampling-volume effects, we recover the intrinsic NH distribution representative of the whole AGN population, f(N_H) dN_H, from the observed one. f(N_H) shows a lognormal shape, peaking around log(N_H)≃ 23.1 and with σ ≃ 1.1. Interestingly, such a distribution shows continuity between the population of Compton-thin and that of Compton-thick AGN. We find that the fraction of absorbed sources (with N_H>1022 cm-2) in the sample is constant (at the level of about 75%) or moderately increasing with redshift. Finally, we compare the optical classification to the X-ray spectral properties, confirming that the correspondence of unabsorbed (absorbed) X-ray sources to optical type I (type II) AGN is accurate for at least 80% of the sources with spectral identification (1/3 of the total X-ray sample).

  4. X-ray temporal and spectral studies of blazars with the Ginga satellite

    NASA Technical Reports Server (NTRS)

    Urry, C. Megan

    1994-01-01

    This is the final report to the National Aeronautics and Space Administration (NASA) concerning NASA grant NAG8-697. This grant was awarded to Dr. C. Megan Urry of the Space Telescope Science Institute in response to a proposal, entitled 'X-Ray Temporal and Spectral Studies of Blazars with the Ginga Satellite', to collaborate with Japanese colleagues in using the Ginga X-ray satellite. The grant was originally awarded on 2/27/88 and expired on 3/31/94. The Ginga X-ray satellite had unprecedented sensitivity in the 2-20 keV energy band, allowing us to make detailed temporal and spectral studies of a large number of blazars, which are a kind of unusually luminous and variable active galactic nuclei. We were successful with several proposals and were able to observe a number of different active galactic nuclei. Our investigations under this grant fall broadly into two categories: (1) Ginga observations of blazars, usually in conjunction with simultaneous multiwavelength observations using other facilities; and (2) the application of calculated pair plasma spectra to the X-ray colors of active galactic nuclei. These are described in turn.

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

    NASA Astrophysics Data System (ADS)

    Khabibullin, I.; Medvedev, P.; Sazonov, S.

    2016-01-01

    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 Θ ˜ 1°) and mildly relativistic (bulk velocity β = Vb/c ˜ 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 normalization 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 high-resolution spectra. We demonstrate this approach in application to Chandra High Energy Transmission Grating Spectrometer spectra of SS 433 in its `edge-on' precession phase, when the contribution from non-jet spectral components is expected to be low. Our model provides a reasonable fit to the 1-3 keV data, while some residuals remain at higher energies, which may be partially attributed to a putative reflection component. Besides SS 433, the model might be used for describing jet components in spectra of other Galactic X-ray binary systems (e.g. 4U 1630-47), ULXs (e.g. Holmberg II X-1), and candidate SS 433 analogues like S26 in NGC 7793 and the radio transient in M82.

  6. THE SIMULTANEOUS OPTICAL-TO-X-RAY SPECTRAL ENERGY DISTRIBUTION OF SOFT X-RAY SELECTED ACTIVE GALACTIC NUCLEI OBSERVED BY SWIFT

    SciTech Connect

    Grupe, Dirk; Komossa, Stefanie; Leighly, Karen M.; Page, Kim L. E-mail: skomossa@mpe.mpg.de

    2010-03-01

    We report Swift observations of a sample of 92 bright soft X-ray selected active galactic nuclei (AGNs). This sample represents the largest number of AGNs observed to study the spectral energy distribution (SED) of AGNs with simultaneous optical/UV and X-ray data. The principal motivation of this study is to understand the SEDs of AGNs in the optical/UV to X-ray regime and to provide bolometric corrections which are important in determining the Eddington ratio L/L {sub Edd}. In particular, we rigorously explore the dependence of the UV-EUV contribution to the bolometric correction on the assumed EUV spectral shape. We find strong correlations of the spectral slopes {alpha}{sub X} and {alpha}{sub UV} with L/L {sub Edd}. Although narrow-line Seyfert 1 galaxies (NLS1s) have steeper {alpha}{sub X} and higher L/L {sub Edd} than broad-line Seyfert 1 galaxies (BLS1s), their optical/UV to X-ray spectral slopes {alpha}{sub ox} and optical/UV slopes {alpha}{sub UV} are very similar. The mean SED of NLS1s shows that in general this type of AGNs appears to be fainter in the UV and at hard X-ray energies than BLS1s. We find a strong correlation between {alpha}{sub X} and {alpha}{sub UV} for AGNs with X-ray spectral slopes {alpha}{sub X}<1.6. For AGNs with steeper X-ray spectra, both this relation and the relation between {alpha}{sub X} and L/L {sub Edd} break down. At {alpha}{sub X}{approx}1.6, L/L {sub Edd} reaches unity. We note an offset in the {alpha}{sub UV}-L/L {sub Edd} relation between NLS1s and BLS1s. We argue that {alpha}{sub UV} is a good estimator of L/L {sub Edd} and suggest that {alpha}{sub UV} can be used to estimate L/L {sub Edd} in high-redshift QSOs. Although NLS1s appear to be highly variable in X-rays, they only vary marginally in the UV.

  7. Investigation of the practical aspects of an additional 0.1 mm copper x-ray spectral filter for cine acquisition mode imaging in a clinical care setting.

    PubMed

    Fetterly, Kenneth A

    2010-11-01

    Minimizing the x-ray radiation dose is an important aspect of patient safety during interventional fluoroscopy procedures. This work investigates the practical aspects of an additional 0.1 mm Cu x-ray beam spectral filter applied to cine acquisition mode imaging on patient dose and image quality. Measurements were acquired using clinical interventional imaging systems. Acquisition images of Solid Water phantoms (15-40 cm) were acquired using x-ray beams with the x-ray tube inherent filtration and using an additional 0.1 mm Cu x-ray beam spectral filter. The skin entrance air kerma (dose) rate was measured and the signal difference to noise ratio (SDNR) of an iodine target embedded into the phantom was calculated to assess image quality. X-ray beam parameters were recorded and analyzed and a primary x-ray beam simulation was performed to assess additional x-ray tube burden attributable to the Cu filter. For all phantom thicknesses, the 0.1 mm Cu filter resulted in a 40% reduction in the entrance air kerma rate to the phantoms and a 9% reduction in the SDNR of the iodine phantom. The expected additional tube load required by the 0.1 mm Cu filter ranged from 11% for a 120 kVp x-ray beam to 43% for a 60 kVp beam. For these clinical systems, use of the 0.1 mm Cu filter resulted in a favorable compromise between reduced skin dose rate and image quality and increased x-ray tube burden. PMID:20938232

  8. Rapid spectral and timing variability of Be/X-ray binaries during type ;II outbursts

    NASA Astrophysics Data System (ADS)

    Reig, P.

    2008-10-01

    X-ray colour-colour (CD) and colour-intensity (HID) diagrams are powerful tools that allow investigation of spectral variability without assuming any spectral model. These diagrams have been used extensively for low-mass X-ray binaries and black-hole candidates, but very few applications have been found for high-mass X-ray binaries. We investigated the spectral and timing variability of four accreting X-ray pulsars with Be-type companions during major X-ray outbursts. The aim is to define source states based on the properties (noise components) of the aperiodic variability in correlation with the position in the colour-colour diagram. Different spectral states were defined according to the value of the X-ray colours and flux. Transient Be/X-ray binaries exhibit two branches in their colour-colour and colour-intensity diagrams: i) the horizontal branch corresponds to a low-intensity state and shows the highest fractional rms, similar to the the island state in atolls and horizontal branch in Z sources; ii) the diagonal branch corresponds to a high-intensity state, in which the source stays for about 75% of the total duration of the outburst. Despite the complexity of the power spectra due to the peaks of the pulse period and its harmonics, the aperiodic variability of Be/X-ray binaries can be described with a relatively low number of Lorentzian components. Some of these components can be associated with the same type of noise as seen in low-mass X-ray binaries, although the characteristic frequencies are about one order of magnitude lower. The analysis of the CD/HID and power spectra results in two different types of Be/X. While in 4U 0115+63, KS 1947+300 and EXO 2030+375 the hard colour decreases as the count rate decreases, it increases in V0332+53. The pattern traced by V0332+53 then results in a Z-shaped track, similar to the low-mass Z sources, without the flaring branch. In contrast, the horizontal branch in 4U 0115+63, KS 1947+300 and EXO 2030+375 corresponds to a low/soft state, which is not seen in other types of X-ray binaries. The noise at very low frequencies follows a power law in V0332+53 (like in LMXB Z), and it is flat-topped in 4U 0115+63, KS 1947+300, and EXO 2030+375 (like in LMXB atoll). V0332+53 shows a noise component coupled with the periodic variability that it is not seen in any of the other three sources.

  9. On the Late-time Spectral Softening Found in X-Ray Afterglows of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Wang, Yuan-Zhu; Zhao, Yinan; Shao, Lang; Liang, En-Wei; Lu, Zu-Jia

    2016-02-01

    Strong spectral softening has been revealed in the late X-ray afterglows of some gamma-ray bursts (GRBs). The scenario of X-ray scattering around the circumburst dusty medium has been supported by previous works due to its overall successful prediction of both the temporal and spectral evolution of some X-ray afterglows. To further investigate the observed feature of spectral softening we now systematically search the X-ray afterglows detected by the X-ray telescope aboard Swift and collect 12 GRBs with significant late-time spectral softening. We find that dust scattering could be the dominant radiative mechanism for these X-ray afterglows regarding their temporal and spectral features. For some well-observed bursts with high-quality data, the time-resolved spectra could be well-produced within the scattering scenario by taking into account the X-ray absorption from the circumburst medium. We also find that during spectral softening the power-law index in the high-energy end of the spectra does not vary much. The spectral softening is mainly manifested by the spectral peak energy continually moving to the soft end.

  10. Spectrally-resolved Soft X-ray Observations and the Temperature Structure of the Solar Corona

    NASA Astrophysics Data System (ADS)

    Caspi, Amir; Warren, Harry; McTiernan, James; Woods, Thomas N.

    2015-04-01

    Solar X-ray observations provide important diagnostics of plasma heating and particle acceleration, during solar flares and quiescent periods. How the corona is heated to its ~1-3 MK nominal temperature remains one of the fundamental unanswered questions of solar physics; heating of plasma to tens of MK during solar flares -- particularly to the hottest observed temperatures of up to ~50 MK -- is also still poorly understood. Soft X-ray emission (~0.1-10 keV; or ~0.1-10 nm) is particularly sensitive to hot coronal plasma and serves as a probe of the thermal processes driving coronal plasma heating. Spectrally- and temporally-resolved measurements are crucial for understanding these energetic processes, but there have historically been very few such observations. We present new solar soft X-ray spectra from the Amptek X123-SDD, measuring quiescent solar X-ray emission from ~0.5 to ~30 keV with ~0.15 keV FWHM resolution from two SDO/EVE calibration sounding rocket underflights in 2012 and 2013. Combined with observations from RHESSI, GOES/XRS, SDO/EVE, and SDO/AIA, the temperature distribution derived from these data suggest significant hot (5-10 MK) emission from active regions, and the 2013 spectra suggest a low-FIP enhancement of only ~1.6 relative to the photosphere, 40% of the usually-observed value from quiescent coronal plasma. We explore the implications of these findings on coronal heating. We discuss future missions for spectrally-resolved soft X-ray observations using the X123-SDD, including the upcoming MinXSS 3U CubeSat using the X123-SDD and scheduled for deployment in mid-2015, and the CubIXSS 6U CubeSat mission concept.

  11. Use of a priori spectral information in the measurement of x-ray flux with filtered diode arrays

    NASA Astrophysics Data System (ADS)

    Marrs, R. E.; Widmann, K.; Brown, G. V.; Heeter, R. F.; MacLaren, S. A.; May, M. J.; Moore, A. S.; Schneider, M. B.

    2015-10-01

    Filtered x-ray diode (XRD) arrays are often used to measure x-ray spectra vs. time from spectrally continuous x-ray sources such as hohlraums. A priori models of the incident x-ray spectrum enable a more accurate unfolding of the x-ray flux as compared to the standard technique of modifying a thermal Planckian with spectral peaks or dips at the response energy of each filtered XRD channel. A model x-ray spectrum consisting of a thermal Planckian, a Gaussian at higher energy, and (in some cases) a high energy background provides an excellent fit to XRD-array measurements of x-ray emission from laser heated hohlraums. If high-resolution measurements of part of the x-ray emission spectrum are available, that information can be included in the a priori model. In cases where the x-ray emission spectrum is not Planckian, candidate x-ray spectra can be allowed or excluded by fitting them to measured XRD voltages. Examples are presented from the filtered XRD arrays, named Dante, at the National Ignition Facility and the Laboratory for Laser Energetics.

  12. Use of a priori spectral information in the measurement of x-ray flux with filtered diode arrays.

    PubMed

    Marrs, R E; Widmann, K; Brown, G V; Heeter, R F; MacLaren, S A; May, M J; Moore, A S; Schneider, M B

    2015-10-01

    Filtered x-ray diode (XRD) arrays are often used to measure x-ray spectra vs. time from spectrally continuous x-ray sources such as hohlraums. A priori models of the incident x-ray spectrum enable a more accurate unfolding of the x-ray flux as compared to the standard technique of modifying a thermal Planckian with spectral peaks or dips at the response energy of each filtered XRD channel. A model x-ray spectrum consisting of a thermal Planckian, a Gaussian at higher energy, and (in some cases) a high energy background provides an excellent fit to XRD-array measurements of x-ray emission from laser heated hohlraums. If high-resolution measurements of part of the x-ray emission spectrum are available, that information can be included in the a priori model. In cases where the x-ray emission spectrum is not Planckian, candidate x-ray spectra can be allowed or excluded by fitting them to measured XRD voltages. Examples are presented from the filtered XRD arrays, named Dante, at the National Ignition Facility and the Laboratory for Laser Energetics. PMID:26520959

  13. Investigation of Solar Flares Using Spectrally, Spatially, and Temporally Resolved Observations in Gamma Rays, Hard X Rays, and Microwaves

    NASA Technical Reports Server (NTRS)

    Crannell, Carol Jo; Oegerle, William (Technical Monitor)

    2003-01-01

    The high-energy components of solar flares radiate at a wide range of wavelengths. We are using spatially, spectrally, and temporally resolved hard X-ray, gamma-ray, and microwave observations of solar flares to investigate flare models and to understand the flare acceleration process. The hard X-ray and gamma-ray observations are obtained with the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) spacecraft that was launched on February 5, 2002. The microwave observations are obtained with the Owens Valley Radio Observatory (OVRO), which has been dedicated to daily observations of solar flares in microwaves with a five-element interferometer since June 1992. These studies are expected to yield exciting new insights into the fundamental physics of the flare acceleration processes.

  14. PIXIE III: a very large area photon-counting CMOS pixel ASIC for sharp X-ray spectral imaging

    NASA Astrophysics Data System (ADS)

    Bellazzini, R.; Brez, A.; Spandre, G.; Minuti, M.; Pinchera, M.; Delogu, P.; de Ruvo, P. L.; Vincenzi, A.

    2015-01-01

    PIXIE III is the third generation of very large area (32 × 25 mm2) pixel ASICs developed by Pixirad Imaging Counters s.r.l. to be used in combination with suitable X-ray sensor materials (Silicon, CdTe, GaAs) in hybrid assemblies using flip-chip bonding. A Pixirad unit module based on PIXIE III shows several advances compared to what has been available up to now. It has a very broad energy range (from 2 to 100 keV before full pulse saturation), high speed (100 ns peaking time), high frame rate (larger than 500 fps), dead-time-free operation, good energy resolution (around 2 keV at 20 keV), high photo-peak fraction and sharp spectral separation between the color images. In this paper the results obtained with PIXIE III both in a test bench set-up as well in X-ray imaging applications are discussed.

  15. High spectral resolution measurements of a solar flare hard X-ray burst

    NASA Technical Reports Server (NTRS)

    Lin, R. P.; Schwartz, R. A.

    1987-01-01

    Observations are reported of an intense solar flare hard X-ray burst on June 27, 1980, made with a balloon-borne array of liquid nitrogen-cooled Ge detector which provided unprecedented spectral resolution (no more than 1 keV FWHM). The hard X-ray spectra throughout the impulsive phase burst fitted well to a double power-law form, and emission from an isothermal 0.1-1 billion K plasma can be specifically excluded. The temporal variations of the spectrum indicate that the hard X-ray burst is made up of two superposed components: individual spikes lasting about 3-15 sec, which have a hard spectrum and a break energy of 30-65 keV; and a slowly varying component characterized by a soft spectrum with a constant low-energy slope and a break energy which increases from 25 kev to at least 100 keV through the event. The double power-law shape indicates that DC electric field acceleration, similar to that occurring in the earth's auroral zone, may be the source of the energetic electrons which produce the hard X-ray emission.

  16. Wide angle crystal spectrometer for angularly and spectrally resolved X-ray scattering experiments.

    PubMed

    Saiz, E Garca; Khattak, F Y; Gregori, G; Bandyopadhyay, S; Clarke, R J; Fell, B; Freeman, R R; Jeffries, J; Jung, D; Notley, M M; Weber, R L; van Woerkom, L; Riley, D

    2007-09-01

    A novel wide angle spectrometer has been implemented with a highly oriented pyrolytic graphite crystal coupled to an image plate. This spectrometer has allowed us to look at the energy resolved spectrum of scattered x rays from a dense plasma over a wide range of angles (approximately 30 degrees ) in a single shot. Using this spectrometer we were able to observe the temporal evolution of the angular scatter cross section from a laser shocked foil. A spectrometer of this type may also be useful in investigations of x-ray line transfer from laser-plasmas experiments. PMID:17902968

  17. X-Ray Fluctuation Power Spectral Densities of Seyfert 1 Galaxies

    NASA Technical Reports Server (NTRS)

    Markowitz, A.; Edelson, R.; Vaughan, S.; Uttley, P.; George, I. M.; Griffiths, R. E.; Kaspi, S.; Lawrence, A.; McHandy, I.; Nandra, K.

    2003-01-01

    By combining complementary monitoring observations spanning long, medium and short time scales, we have constructed power spectral densities (PSDs) of six Seyfert 1 galaxies. These PSDs span approx. greater than 4 orders of magnitude in temporal frequency, sampling variations on time scales ranging from tens of minutes to over a year. In at least four cases, the PSD shows a "break," a significant departure from a power law, typically on time scales of order a few days. This is similar to the behavior of Galactic X-ray binaries (XRBs), lower mass compact systems with breaks on time scales of seconds. NGC 3783 shows tentative evidence for a doubly-broken power law, a feature that until now has only been seen in the (much better-defined) PSDs of low-state XRBs. It is also interesting that (when one previously-observed object is added to make a small sample of seven), an apparently significant correlation is seen between the break time scale T and the putative black hole mass M(sub BH), while none is seen between break time scale and luminosity. The data are consistent with the linear relation T = M(sub BH) /10(exp 6.5) solar mass; extrapolation over 6-7 orders of magnitude is in reasonable agreement with XRBs. All of this strengthens the case for a physical similarity between Seyfert 1s and XRBs.

  18. High Spectral Resolution, High Cadence, Imaging X-Ray Microcalorimeters for Solar Physics

    NASA Technical Reports Server (NTRS)

    Bandler, Simon R.; Bailey, Catherine N.; Bookbinder, Jay A.; DeLuca, Edward E.; Chervenak, Jay A.; Eckart, Megan E.; Finkbeiner, Fred M.; Kelley, Daniel P.; Kelley, Richard L.; Kilbourne, Caroline A.; Porter, Frederick S.; Sadleir, Jack E.; Smith, Stephen J.; Smith, Randall K.

    2010-01-01

    High spectral resolution, high cadence, imaging x-ray spectroscopy has the potential to revolutionize the study of the solar corona. To that end we have been developing transition-edge-sensor (TES) based x-ray micro calorimeter arrays for future solar physics missions where imaging and high energy resolution spectroscopy will enable previously impossible studies of the dynamics and energetics of the solar corona. The characteristics of these x-ray microcalorimeters are significantly different from conventional micro calorimeters developed for astrophysics because they need to accommodate much higher count rates (300-1000 cps) while maintaining high energy resolution of less than 4 eV FWHM in the X-ray energy band of 0.2-10 keV. The other main difference is a smaller pixel size (less than 75 x 75 square microns) than is typical for x-ray micro calorimeters in order to provide angular resolution less than 1 arcsecond. We have achieved at energy resolution of 2.15 eV at 6 keV in a pixel with a 12 x 12 square micron TES sensor and 34 x 34 x 9.1 micron gold absorber, and a resolution of 2.30 eV at 6 keV in a pixel with a 35 x 35 micron TES and a 57 x 57 x 9.1 micron gold absorber. This performance has been achieved in pixels that are fabricated directly onto solid substrates, ie. they are not supported by silicon nitride membranes. We present the results from these detectors, the expected performance at high count-rates, and prospects for the use of this technology for future Solar missions.

  19. Spectral evolution of active galactic nuclei: A unified description of the X-ray and gamma

    NASA Technical Reports Server (NTRS)

    Leiter, D.; Boldt, E.

    1982-01-01

    A model for spectral evolution is presented whereby active galactic nuclei (AGN) of the type observed individually emerge from an earlier stage at z approx = 4 in which they are the thermal X-ray sources responsible for most of the cosmic X-ray background (CXB). The conjecture is pursued that these precursor objects are initially supermassive Schwarzschild black holes with accretion disks radiating near the Eddington luminosity limit. It is noted that after approx. 10 to the 8th power years these central black holes are spun-up to a canonical Kerr equilibrium state (A/M = 0.998; Thorne 1974) and shown how they then can lead to spectral evolution involving non-thermal emission extending to gamma rays, at the expense of reduced thermal disk radiation. That major portion of the CXB remaining after the contribution of usual AGN are considered, while a superposition of AGN sources at z 1 can account for the gamma ray background. Extensive X-ray measurements carried out with the HEAO 1 and 2 missions as well as gamma ray and optical data are shown to compare favorably with principal features of this model.

  20. New X-ray spectral observations of NGC 4151 with ASCA

    NASA Technical Reports Server (NTRS)

    Weaver, K. A.; Yaqoob, T.; Holt, S. S.; Mushotzky, R. F.; Matsuoka, M.; Yamauchi, M.

    1994-01-01

    We present new X-ray spectral data for the well-studied Seyfert galaxy NGC 4151, which was observed twice for about 20 ks each during the ASCA performance verification phase, once on 1993 May 25 and again on 1993 November 5. The source underwent complex spectral variability, and the observed 2-10 keV flux increased by a factor of 2 while the intrinsic 2-10 keV flux increased by no more than 20%. The data can be modeled with either a dual cold absorber plus a soft X-ray excess consisting of scattered continuum flux and an additional 'ultrasoft' X-ray excess component, or a warm absorber plus scattered continuum flux. There is evidence for variability at less than 1 keV energies that is unrelated to the 2-10 keV continuum. For an ionized-absorber description of NGC 4151, changes in the ionization state of the absorber appear to be unrelated to changes in the ionizing continuum.

  1. X-ray spectral variability of seven LINER nuclei with XMM-Newton and Chandra data

    NASA Astrophysics Data System (ADS)

    Hernndez-Garca, L.; Gonzlez-Martn, O.; Mrquez, I.; Masegosa, J.

    2013-08-01

    Context. One of the most distinctive features in active galactic nuclei (AGN) is the variability of their emission. Variability has been discovered at X-ray, UV, and radio frequencies on timescales from hours to years. Among the AGN family and according to theoretical studies, low-ionization nuclear emission line region (LINER) nuclei would be objects variable on long timescales. Aims: Our purpose is to investigate spectral X-ray variability in LINERs and to understand the nature of these types of objects, as well as their accretion mechanism. Methods: Chandra and XMM-Newton public archives were used to compile X-ray spectra of seven LINER nuclei at different epochs with timescales of years. To search for variability we fit all spectra from the same object with a set of models to identify the parameters responsible for the variability pattern. We also analyzed the light curves to search for short timescale (from hours to days) variability. Whenever possible, UV variability was also studied. Results: We found spectral variability in four objects (NGC 1052, NGC 3226, NGC 4278, and NGC 4552), with variations mostly related to hard energies (2-10 keV). These variations are generated by several possible changes that act either alone or in combination: changes in the soft excess or in the absorber. Added to this can be intrinsic variations of the source, which may also be responsible by themselves for the spectral variability. These variations occurred within years, the shortest timescale being found for NGC 4278 (two months). Another two galaxies (NGC 4261 and NGC 5846) apparently do not vary. No short timescale variations during individual observations were found. Our analysis confirms the previously reported anticorrelation between the X-ray spectral index, ?, and the Eddington ratio, Lbol/LEdd, and also the correlation between the X-ray to UV flux ratio, ?ox, and the Eddington ratio, Lbol/LEdd. These results support an advection dominated accretion flow as the accretion mechanism in LINERs. Tables 2-11 and Appendices are available in electronic form at http://www.aanda.org

  2. A statistical relation between the X-ray spectral index and Eddington ratio of active galactic nuclei in deep surveys

    NASA Astrophysics Data System (ADS)

    Brightman, M.; Silverman, J. D.; Mainieri, V.; Ueda, Y.; Schramm, M.; Matsuoka, K.; Nagao, T.; Steinhardt, C.; Kartaltepe, J.; Sanders, D. B.; Treister, E.; Shemmer, O.; Brandt, W. N.; Brusa, M.; Comastri, A.; Ho, L. C.; Lanzuisi, G.; Lusso, E.; Nandra, K.; Salvato, M.; Zamorani, G.; Akiyama, M.; Alexander, D. M.; Bongiorno, A.; Capak, P.; Civano, F.; Del Moro, A.; Doi, A.; Elvis, M.; Hasinger, G.; Laird, E. S.; Masters, D.; Mignoli, M.; Ohta, K.; Schawinski, K.; Taniguchi, Y.

    2013-08-01

    We present an investigation into how well the properties of the accretion flow on to a supermassive black hole may be coupled to those of the overlying hot corona. To do so, we specifically measure the characteristic spectral index, ?, of a power-law energy distribution, over an energy range of 2-10 keV, for X-ray selected, broad-lined radio-quiet active galactic nuclei (AGN) up to z 2 in Cosmic Evolution Survey (COSMOS) and Extended Chandra Deep Field South (E-CDF-S). We test the previously reported dependence between ? and black hole mass, full width at half-maximum (FWHM) and Eddington ratio using a sample of AGN covering a broad range in these parameters based on both the Mg II and H? emission lines with the later afforded by recent near-infrared spectroscopic observations using Subaru/Fibre Multi Object Spectrograph. We calculate the Eddington ratios, ?Edd, for sources where a bolometric luminosity (LBol) has been presented in the literature, based on spectral energy distribution fitting, or, for sources where these data do not exist, we calculate LBol using a bolometric correction to the X-ray luminosity, derived from a relationship between the bolometric correction and LX/L3000. From a sample of 69 X-ray bright sources (>250 counts), where ? can be measured with greatest precision, with an estimate of LBol, we find a statistically significant correlation between ? and ?Edd, which is highly significant with a chance probability of 6.59 10-8. A statistically significant correlation between ? and the FWHM of the optical lines is confirmed, but at lower significance than with ?Edd indicating that ?Edd is the key parameter driving conditions in the corona. Linear regression analysis reveals that ? = (0.32 0.05) log10?Edd + (2.27 0.06) and ? = (-0.69 0.11) log10(FWHM/km s-1) + (4.44 0.42). Our results on ?-?Edd are in very good agreement with previous results. While the ?-?Edd relationship means that X-ray spectroscopy may be used to estimate black hole accretion rate, considerable dispersion in the correlation does not make this viable for single sources, however could be valuable for large X-ray spectral samples, such as those to be produced by eROSITA.

  3. The x-ray calibration facility of the laser integration line in the 0.9-10 keV range: The high energy x-ray source and some applications

    SciTech Connect

    Hubert, S.; Dubois, J. L.; Gontier, D.; Lidove, G.; Reverdin, C.; Soullie, G.; Stemmler, P.; Villette, B.

    2010-05-15

    The laser integration line (LIL) located at CEA-CESTA is equipped with x-ray plasma diagnostics using different kinds of x-ray components such as filters, mirrors, crystals, detectors, and cameras. The CEA-DAM of Arpajon is currently developing x-ray calibration methods and carrying out absolute calibration of LIL x-ray photodetectors. To guarantee LIL measurements, detectors such as x-ray cameras must be regularly calibrated close to the facility. A new x-ray facility is currently available to perform these absolute x-ray calibrations. This paper presents the x-ray tube based high energy x-ray source delivering x-ray energies ranging from 0.9 to 10 keV by means of an anode barrel. The purpose of this source is mainly to calibrate LIL x-ray cameras but it can also be used to measure x-ray filter transmission of plasma diagnostics. Different x-ray absolute calibrations such as x-ray streak and framing camera yields, x-ray charge-coupled device quantum efficiencies, and x-ray filter transmissions are presented in this paper. A x-ray flat photocathode detector sensitivity calibration recently performed for a CEA Z-pinch facility is also presented.

  4. The x-ray calibration facility of the laser integration line in the 0.9-10 keV range: the high energy x-ray source and some applications.

    PubMed

    Hubert, S; Dubois, J L; Gontier, D; Lidove, G; Reverdin, C; Soulli, G; Stemmler, P; Villette, B

    2010-05-01

    The laser integration line (LIL) located at CEA-CESTA is equipped with x-ray plasma diagnostics using different kinds of x-ray components such as filters, mirrors, crystals, detectors, and cameras. The CEA-DAM of Arpajon is currently developing x-ray calibration methods and carrying out absolute calibration of LIL x-ray photodetectors. To guarantee LIL measurements, detectors such as x-ray cameras must be regularly calibrated close to the facility. A new x-ray facility is currently available to perform these absolute x-ray calibrations. This paper presents the x-ray tube based high energy x-ray source delivering x-ray energies ranging from 0.9 to 10 keV by means of an anode barrel. The purpose of this source is mainly to calibrate LIL x-ray cameras but it can also be used to measure x-ray filter transmission of plasma diagnostics. Different x-ray absolute calibrations such as x-ray streak and framing camera yields, x-ray charge-coupled device quantum efficiencies, and x-ray filter transmissions are presented in this paper. A x-ray flat photocathode detector sensitivity calibration recently performed for a CEA Z-pinch facility is also presented. PMID:20515133

  5. Spectral energetic properties of the X-ray-boosted photoionization by an intense few-cycle laser

    NASA Astrophysics Data System (ADS)

    Ge, Yu-Cheng; He, Hai-Ping

    2014-07-01

    We report a discovery that an intense few-cycle laser pulse passing through gas leaves a fingerprint of its field envelope on the photoelectron energy spectrum, which involves continuous X-ray radiations. The spectrum resulting from the photoionization processes includes significant quantum enhancement and interference and exhibits interesting energetic properties. The spectral cut-off energies reflect the strength, time, and interference of the laser field modulation on the photoelectron energy. These energetic properties suggest a new method for precise intense-laser-pulse measurement in situ. The method has the advantages of accuracy, simplicity, speed, and large dynamic ranges (up to many orders of intensity).

  6. Hercules X-1: Spectral Variability of an X-Ray Pulsar in a Stellar Binary System. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Pravdo, S. H.

    1976-01-01

    A cosmic X-ray spectroscopy experiment onboard the Orbiting Solar Observatory 8 (OSO-8), observed Her x-1 continuously for approximately 8 days. Spectral-temporal correlations of the X-ray emission were obtained. The major results concern observations of: (1) iron band emission, (2) spectral hardening (increase in effective x-ray temperature) within the X-ray pulse, and (3) a transition from an X-ray low state to a high state. The spectrum obtained prior to the high state can be interpreted as reflected emission from a hot coronal gas surrounding an accretion disk, which itself shields the primary X-ray source from the line of sight during the low state. The spectral hardening within the X-ray pulse was indicative of the beaming mechanism at the neutron star surface. The hardest spectrum by pulse phase was identified with the line of sight close to the Her x-1 magnetic dipole axis, and the X-ray pencil beam become harder with decreasing angle between the line of sight and the dipole axis.

  7. X-ray efficiency of phosphor screens in the 20--60 kV range

    SciTech Connect

    Giakoumakis, G.E.

    1988-07-15

    The absolute efficiency of phosphor screens under x-ray excitation is studied for tube voltages ranging from 20 to 60 kV. The screens were prepared of ZnS:Cu, ZnCdS:Ag, Y/sub 2/O/sub 2/S:Tb, Gd/sub 2/O/sub 2/S:Tb, and CaWO/sub 4/, which are the phosphors most commonly used in the x-ray applications. This efficiency appears to be about 100 times lower than the efficiency of the same screens under fluoroscopy conditions.

  8. Circularly polarization line filters in the soft X-ray range

    NASA Astrophysics Data System (ADS)

    Goedkoop, J. B.; Fuggle, J. C.; Thole, B. T.; Van der Laan, G.; Sawatzky, G. A.

    1988-12-01

    A feasibility study of the application of the recently discovered strong magnetic X-ray dichroism of rare earth materials to the production of circularly polarized X-rays is reported. A device is described that can be inserted downstream from a high resolution double beryl crystal monochromator. Calculations show that 45% transmission can be obtained with filters that yield 99% circular polarization in the energy range 950-1500 eV. Advantages of the proposed device are the low costs, the ease of installation and the high product of transmission polarization.

  9. Multivariate analysis of X-ray, ion and electron spectral images: from surface to 3D materials characterization.

    SciTech Connect

    Kotula, Paul Gabriel; Keenan, Michael Robert

    2005-02-01

    Spectral imaging where a complete spectrum is collected from each of a series of spatial locations (1D lines, 2D images or 3D volumes) is now available on a wide range of analytical tools - from electron and x-ray to ion beam instruments. With this capability to collect extremely large spectral images comes the need for automated data analysis tools that can rapidly and without bias reduce a large number of raw spectra to a compact, chemically relevant, and easily interpreted representation. It is clear that manual interrogation of individual spectra is impractical even for very small spectral images (< 5000 spectra). More typical spectral images can contain tens of thousands to millions of spectra, which given the constraint of acquisition time may contain between 5 and 300 counts per 1000-channel spectrum. Conventional manual approaches to spectral image analysis such as summing spectra from regions or constructing x-ray maps are prone to bias and possibly error. One way to comprehensively analyze spectral image data, which has been automated, is to utilize an unsupervised self-modeling multivariate statistical analysis method such as multivariate curve resolution (MCR). This approach has proven capable of solving a wide range of analytical problems based upon the counting of x-rays (SEM/STEM-EDX, XRF, PIXE), electrons (EELS, XPS) and ions (TOF-SIMS). As an example of the MCR approach, a STEM x-ray spectral image from a ZrB2-SiC composite was acquired and analyzed. The data were generated in a FEI Tecnai F30-ST TEM/STEM operated at 300kV, equipped with an EDAX SUTW x-ray detector. The spectral image was acquired with the TIA software on the STEM at 128 by 128 pixels (12nm/pixel) for 100msec dwell per pixel (total acquisition time was 30 minutes) with a probe of approximately the same size as each pixel. Each spectrum in the image had, on average, 500 counts. The calculation took 5 seconds on a PC workstation with dual 2.4GHz PentiumIV Xeon processors and 2Gbytes of RAM and resulted in four chemically relevant components, which are shown in Figure 1. The analysis region was at a triple junction of three ZrB2 grains that contained zirconium oxide, aluminum oxide and a glass phase. The power of unbiased statistical methods, such as MCR as applied here, is that no a priori knowledge of the material's chemistry is required. The algorithms, in this case, effectively reduced over 16,000 2000-channel spectra (64Mbytes) to four images and four spectral shapes (72kbytes), which in this case represent chemical phases. This three order of magnitude compression is achieved rapidly with no loss of chemical information. There is also the potential to correlate multiple analytical techniques like, for example, EELS and EDS in the STEM adding sensitivity to light elements as well as bonding information for EELS to the more comprehensive spectral coverage of EDS.

  10. X-RAY SPECTRAL CUTOFF AND THE LACK OF HARD X-RAY EMISSION FROM TWO ULTRALUMINOUS X-RAY SOURCES M81 X-6 AND HOLMBERG IX X-1

    SciTech Connect

    Dewangan, G. C.; Misra, R.; Jithesh, V.; Ravikumar, C. D.

    2013-07-10

    We present broadband X-ray spectral study of two ultraluminous X-ray sources (ULXs), M81 X-6 and Holmberg IX X-1, based on Suzaku and XMM-Newton observations. We perform joint broadband spectral analysis of the brightest sources in the field, i.e., the two ULXs and the active galactic nucleus (AGN) in M81, and demonstrate that the X-ray spectra of the ULXs cut off at energies {approx}> 3 keV with negligible contribution at high energies in the Suzaku HXD/PIN band. The 90% upper limit on the 10-30 keV band luminosity of an underlying broadband power-law component is 3.5 Multiplication-Sign 10{sup 38} erg s{sup -1} for M81 X-6 and 1.2 Multiplication-Sign 10{sup 39} erg s{sup -1} for Holmberg IX X-1. These limits are more than an order of magnitude lower than the bolometric (0.1-30 keV) luminosity of 6.8 Multiplication-Sign 10{sup 39} erg s{sup -1} for M81 X-6 and 1.9 Multiplication-Sign 10{sup 40} erg s{sup -1} for Holmberg IX X-1. Our results confirm earlier indications of spectral cutoffs inferred from the XMM-Newton observations of bright ULXs and show that there is not an additional high-energy power-law component contributing significantly to the X-ray emission. The spectral form of the two ULXs are very different from those of Galactic black hole X-ray binaries (BHBs) or AGNs. This implies that the ULXs are neither simply scaled-up versions of stellar-mass BHBs nor scaled-down versions of AGNs.

  11. Anomalous x-ray scattering studies of short-, intermediate- and extended-range order in glasses

    SciTech Connect

    Price, D.L.; Saboungi, M.L.; Armand, P.; Cox, D.E.

    1998-08-01

    The authors present the formalism of anomalous x-ray scattering as applied to partial structure analysis of disordered materials, and give an example of how the technique has been applied, together with that of neutron diffraction, to investigate short-, intermediate- and extended-range order in vitreous germania and rubidium germanate.

  12. Fluctuation x-ray microscopy for measuring medium-range order.

    SciTech Connect

    Fan, L.; McNulty, I.; Paterson, D.; Treacy, M. M. J.; Gibson, J. M.; Arizona State Univ.

    2005-01-01

    Many x-ray techniques exist to probe long- and short-range order in matter, in real space by imaging and in reciprocal space by diffraction and scattering. However, measuring medium-range order (MRO) in disordered materials is a long-standing problem. Based on fluctuation electron microscopy, which was applied successfully to the understanding of MRO in amorphous materials, we have developed fluctuation x-ray microscopy (FXM). This novel approach offers quantitative insight into medium-range correlations in materials at nanometer and larger length scales. It examines spatially resolved fluctuations in the intensity of a series of x-ray speckle patterns. The speckle variance depends on higher order correlations that are more sensitive to MRO. Systematically measuring the speckle variance as function of the momentum transfer and x-ray illumination size produces a fluctuation map that contains information about the degree of MRO and the correlation length. This approach can be used for the exploration of MRO and subtle spatial structural changes in a wide range of disordered materials from soft condensed matter to nanowire arrays, semiconductor quantum dot arrays and magnetic materials. It will also help us to understand the mechanisms of order-disorder transitions and may lead to control of ordering, which is important in developing ordered structures tailored for particular applications. A theory for FXM and preliminary experimental results from polystyrene latex spheres are discussed in this paper.

  13. Rapid spectral and flux time variations in a solar burst observed at various dm-mm wavelengths and at hard X-rays

    NASA Technical Reports Server (NTRS)

    Zodivaz, A. M.; Kaufmann, P.; Correia, E.; Costa, J. E. R.; Takakura, T.; Cliver, E. W.; Tapping, K. F.

    1986-01-01

    A solar burst was observed with high sensitivity and time resolution at cm-mm wavelengths by two different radio observatories (Itapetinga and Algonquin), with high spectral time resolution at dm-mm wavelengths by patrol instruments (Sagamore Hill), and at hard X-rays (HXM Hinotori). At the onset of the major burst time structure there was a rapid rise in the spectral turnover frequency (from 5 to 15 GHz), in about 10s, coincident to a reduction of the spectral index in the optically thin part of the spectrum. The burst maxima were not time coincident at the optically thin radio frequencies and at the different hard X-ray energy ranges. The profiles at higher radio frequencies exhibited better time coincidence to the high energy X-rays. The hardest X-ray spectrum (-3) coincided with peak radio emission at the higher frequency (44 GHz). The event appeared to be built up by a first major injection of softer particles followed by other injections of harder particles. Ultrafast time structures were identified as superimposed on the burst emission at the cm-mm high sensitivity data at X-rays, with predominant repetition rates ranging from 2.0 to 3.5 Hz.

  14. Rapid spectral and flux time variations in a solar burst observed at various dm-mm wavelengths and at hard X-rays

    NASA Astrophysics Data System (ADS)

    Zodivaz, A. M.; Kaufmann, P.; Correia, E.; Costa, J. E. R.; Takakura, T.; Cliver, E. W.; Tapping, K. F.

    A solar burst was observed with high sensitivity and time resolution at cm-mm wavelengths by two different radio observatories (Itapetinga and Algonquin), with high spectral time resolution at dm-mm wavelengths by patrol instruments (Sagamore Hill), and at hard X-rays (HXM Hinotori). At the onset of the major burst time structure there was a rapid rise in the spectral turnover frequency (from 5 to 15 GHz), in about 10s, coincident to a reduction of the spectral index in the optically thin part of the spectrum. The burst maxima were not time coincident at the optically thin radio frequencies and at the different hard X-ray energy ranges. The profiles at higher radio frequencies exhibited better time coincidence to the high energy X-rays. The hardest X-ray spectrum (-3) coincided with peak radio emission at the higher frequency (44 GHz). The event appeared to be built up by a first major injection of softer particles followed by other injections of harder particles. Ultrafast time structures were identified as superimposed on the burst emission at the cm-mm high sensitivity data at X-rays, with predominant repetition rates ranging from 2.0 to 3.5 Hz.

  15. Origin of the X-ray broad iron spectral feature in GRS 1915+105

    NASA Astrophysics Data System (ADS)

    Mizumoto, Misaki; Ebisawa, Ken; Tsujimoto, Masahiro; Inoue, Hajime

    2016-01-01

    The X-ray spectrum of GRS 1915+105 is known to have a "broad iron spectral feature" in the spectral hard state. Similar spectral features are often observed in active galactic nuclei (AGNs) and other black-hole binaries (BHBs), and several models have been proposed for explaining it. In order to distinguish spectral models, time variation provides an important key. In AGNs, variation amplitude has been found to drop significantly at the iron K-energy band at timescales of 10 ks. If spectral variations of black holes are normalized by their masses, the spectral variations of BHBs on timescales of sub-seconds should exhibit similar characteristics to those of AGNs. In this paper, we investigated spectral variations of GRS 1915+105 at timescales down to 10 ms. This was made possible for the first time with the Suzaku XIS Parallel-sum clocking (P-sum) mode, which has the CCD energy-resolution as well as a time-resolution of 7.8 ms. Consequently, we found that the variation amplitude of GRS 1915+105 does not drop at the iron K-energy band on any timescales from 0.06 s to 63000 s, and that the entire X-ray flux and the iron feature are independently variable at timescales of hours. These are naturally understood in the framework of the "partial covering" model, in which variation timescales of the continuum flux and partial absorbers are independent. The difference of the energy dependence of the variation amplitude between AGNs and BHBs is presumably due to different mechanisms of the outflow winds, i.e., the partial absorbers are due to UV-line driven winds (AGNs) or thermally driven winds (BHBs).

  16. Temporal resolved x-ray penumbral imaging technique using heuristic image reconstruction procedure and wide dynamic range x-ray streak camera

    SciTech Connect

    Fujioka, Shinsuke; Shiraga, Hiroyuki; Azechi, Hiroshi; Nishimura, Hiroaki; Izawa, Yasukazu; Nozaki, Shinya; Chen, Yen-wei

    2004-10-01

    Temporal resolved x-ray penumbral imaging has been developed using an image reconstruction procedure of the heuristic method and a wide dynamic range x-ray streak camera (XSC). Reconstruction procedure of the penumbral imaging is inherently intolerant to noise, a reconstructed image is strongly distorted by artifacts caused by noise in a penumbral image. Statistical fluctuation in the number of detected photon is the dominant source of noise in an x-ray image, however acceptable brightness of an image is limited by dynamic range of an XSC. The wide dynamic range XSC was used to obtain penumbral images bright enough to be reconstructed. Additionally, the heuristic method was introduced in the penumbral image reconstruction procedure. Distortion of reconstructed images is sufficiently suppressed by these improvements. Density profiles of laser driven brominated plastic and tin plasma were measured with this technique.

  17. Spectral and timing characterization of the X-ray source 1RXS J194211.9+255552

    NASA Astrophysics Data System (ADS)

    D'A, A.; Cusumano, G.; La Parola, V.; Segreto, A.

    2015-08-01

    We report on the first spectral and timing characterization of the transient X-ray source 1RXS J194211.9+255552 using all available data from the Swift X-ray satellite. We used 10 years of hard X-ray data from the Burst Alert Telescope (BAT) to characterize its long-term behaviour and to search for long periodicities, finding evidence for a periodic modulation at 166.5 0.5 d, that we interpret as the orbital period of the source. The folded light curve reveals that the X-ray emission is mostly concentrated in a restricted phase-interval and we propose to associate 1RXS J194211.9+255552 to the class of the Be X-ray binaries. This is also supported by the results of the spectral analysis, where we used the BAT data and three pointed Swift/XRT observations to characterize the X-ray broad-band spectral shape. We found mild spectral variability in soft X-rays that can be accounted for by a varying local neutral absorber, while the intrinsic emission is consistent with a hard power law multiplied by a high-energy exponential cut-off as typically observed in this class of systems.

  18. Understanding X-ray Spectral and Timing Characteristics of Active Galactic Nuclei by a Novel Picture with Multiple Primary Emission

    NASA Astrophysics Data System (ADS)

    Noda, H.; Makishima, K.; Yamada, S.; Miyake, K.

    2014-07-01

    Our understanding of the central engine of type I Active Galactic Nuclei (AGNs) has been hampered by spectral ambiguity among different X-ray components: e.g., Comptonized primary emission, secondary components possibly affected by strong relativistic effects (e.g., Miniutti et al. 2007), and/or complex partial absorption (e.g., Miller et al. 2008). With a variability-assisted spectral analysis method developed in Noda et al. (2011, 2013), we succeeded in model-independently decomposing the AGN spectra, and establishing a novel view of the engine, that it consists of multiple primary X-ray continua with distinct spectral shapes, variability timescales, and Eddington-ratio dependences (Noda et al. 2013). The novel view with the multiple primary X-ray components can explain several long-lasting problems with the AGN central engine. The hardest of the primary components can now partially explain the "too strong hard X-ray hump", and make the secondary reflection strength moderate. The well-known X-ray spectral softening, when a source brightens, can be successfully reproduced by an increasing dominance of a softer-slope primary component towards higher Eddington ratios. Furthermore, the puzzling lack of good optical vs. X-ray intensity correlation, in some AGNs, can be solved by considering that the optical emission is correlated only with some of the primary X-ray components.

  19. Ion-heated thermal Comptonization models and x-ray spectral correlations in active galactic nuclei

    SciTech Connect

    Dermer, C.D.

    1989-11-01

    Recent Ginga observations of the Seyfert 1 galaxies NGC 4051 and MCG 6-30-15 show a positive correlation between the 2-10 keV luminosity and photon spectral index {alpha}. Similar behavior has also been reported in Exosat and Einstein observations of other active galactic nuclei, and is suggested in hard x-ray low-state data of the galactic black-hole candidate Cygnus X-1. A two-temperature thermal Comptonization model with internal soft-photon production provides a simple explanation for this correlation. The electron temperature, determined by a balance between ion heating and radiative cooling, decreases in response to an enhancement of the soft photon flux, resulting in a softening of the spectrum and an increase in the soft x-ray luminosity. The bulk of the soft photons are produced through pion production in collisions between the hot ions. Pivoting of the spectrum at photon energies {var epsilon} > 50 keV is a consequence of variations in the ion temperature. An important test of the model would be time correlations between soft and hard x-ray bands. 17 refs., 9 figs., 1 tab.

  20. Spectral-luminosity evolution of active galactic nuclei and the cosmic X-ray background

    NASA Technical Reports Server (NTRS)

    Leiter, Darryl; Boldt, Elihu

    1991-01-01

    Black hole accretion disk dynamo processes are generally regarded as the central power source for AGN (Rees, 1984). If the precursor active galaxies for such AGN are formed at redshift z greater than about 4 and contain initial central seed black holes about 10 exp 6 solar masses, then the Eddington limited X-ray radiation emitted during their lifetime will undergo the phenomenon of 'spectral-luminosity evolution'. When accretion disks are first formed at the onset of galaxy formation, the accretion rate occurs at high values of luminosity/size compactness parameter L/R greater than 10 exp 30 erg/cm-sec. Such high values of L/R generate dynamic constraints which suppress nonthermal black hole accretion disk dynamo processes in favor of thermal processes. This causes the spectrum of X-radiation emitted by early AGN to be predominantly thermal. A superposition of such thermal, comptonized PAG sources can account for the residual cosmic X-ray background and can act as a source of X-ray heating of the intergalactic medium for z greater than about 4.

  1. Spectrally and angularly resolved x-ray scattering measurements of shock-compressed aluminum

    NASA Astrophysics Data System (ADS)

    Fletcher, Luke; High Energy Density Science Collaboration

    2013-10-01

    Measurements of the strength in the ionic structure factor at various scattering angles is important for accurate first-principle calculations of material properties in the high pressure and temperature phase. In this study, spectrally resolved XRTS measurements in combination with proof-of-principle, single shot 2D angularly resolved x-ray scattering measurements of changes in the ion-ion correlation peak for both single and double (counter-propagating) shocks have been observed in Al foils. A binary 527 nm, 2 GW laser system available at the MEC station of the LCLS facility has been used to compress 25 ?m and 50 ?m thick Al targets approximately 2x and 3x the solid density respectively. A drive intensity of 6x1014 W/cm2 on each irradiated surface was used to generate high pressure shock waves into the sample while 8 keV x-rays from the LCLS were used to probe the compressed targets for both single and double shocked geometries. The results will show that the elastic x-ray scattering amplitude, angularly resolved, shifts to higher wave numbers with increasing density, while the width and peak amplitude provide information on the temperature and ionization state. This work is supported by DOE Office of Basic Energy Sciences, Materials Sciences and Engineering Division, under Contract DE-AC02-76SF00515.

  2. Crosscheck of different techniques for two dimensional power spectral density measurements of x-ray optics

    SciTech Connect

    Yashchuk, Valeriy V.; Irick, Steve C.; Gullikson, Eric M.; Howells, Malcolm R.; MacDowell, Alastair A.; McKinney, Wayne R.; Salmassi, Farhad; Warwick, Tony

    2005-07-12

    The consistency of different instruments and methods for measuring two-dimensional (2D) power spectral density (PSD) distributions are investigated. The instruments are an interferometric microscope, an atomic force microscope (AFM) and the X-ray Reflectivity and Scattering experimental facility, all available at Lawrence Berkeley National Laboratory. The measurements were performed with a gold-coated mirror with a highly polished stainless steel substrate. It was shown that these three techniques provide essentially consistent results. For the stainless steel mirror, an envelope over all measured PSD distributions can be described with an inverse power-law PSD function. It is also shown that the measurements can be corrected for the specific spatial frequency dependent systematic errors of the instruments. The AFM and the X-ray scattering measurements were used to determine the modulation transfer function of the interferometric microscope. The corresponding correction procedure is discussed in detail. Lower frequency investigation of the 2D PSD distribution was also performed with a long trace profiler and a ZYGO GPI interferometer. These measurements are in some contradiction, suggesting that the reliability of the measurements has to be confirmed with additional investigation. Based on the crosscheck of the performance of all used methods, we discuss the ways for improving the 2D PSD characterization of X-ray optics.

  3. X-ray spectral variability of LINERs selected from the Palomar sample

    NASA Astrophysics Data System (ADS)

    Hernández-García, L.; González-Martín, O.; Masegosa, J.; Márquez, I.

    2014-09-01

    Context. Variability is a general property of active galactic nuclei (AGN). The way in which these changes occur at X-rays is not yet clearly understood. In the particular case of low-ionization nuclear emission line region (LINER) nuclei, variations on the timescales from months to years have been found for some objects, but the main driver of these changes is still debated. Aims: The main purpose of this work is to investigate the X-ray variability in LINERs, including the main driver of these variations, and to search for possible differences between type 1 and 2 objects. Methods: We examined the 18 LINERs in the Palomar sample with data retrieved from the Chandra and/or XMM-Newton archives that correspond to observations gathered at different epochs. All the spectra for the same object were fitted simultaneously to study long-term variations. The nature of the variability patterns were studied by allowing different parameters to vary during the spectral fit. Whenever possible, short-term variations from the analysis of the light curves and long-term UV variability were studied. Results: Short-term variations are not reported in X-rays. Three LINERs are classified as non-AGN candidates in X-rays, all of them are Compton-thick candidates; none of them show variations at these frequencies, and two of them vary in the UV. Long-term X-ray variations were analyzed in 12 out of 15 AGN candidates; about half of them showed variability (7 out of the 12). At UV frequencies, most of the AGN candidates with available data are variable (five out of six). Thus, 13 AGN candidates are analyzed at UV and/or X-rays, ten of which are variable at least in one energy band. None of the three objects that do not vary in X-rays have available UV data. This means that variability on long-timescales is very common in LINERs. These X-ray variations are mainly driven by changes in the nuclear power, while changes in absorptions are found only for NGC 1052. We do not find any difference between type 1 and 2 LINERs, neither in the number of variable cases (three out of five type 1 and four out of seven type 2 LINERs), nor in the nature of the variability pattern. We find indications of an anticorrelation between the slope of the power law, Γ, and the Eddington ratio. Conclusions: LINERs are definitely variable sources irrespective of whether they are classified as optical type 1 or 2. Their BH masses, accretion rates, and variability timescales place them in the same plane as more powerful AGN at X-rays. However, our results suggest that the accretion mechanism in LINERs may be different. UV variations of some type 2 LINERs were found, this could support the hypothesis of a torus that disappears at low luminosities. Appendices are available in electronic form at http://www.aanda.org

  4. The Extragalactic X-ray Background in the 0.2 - 2 keV Range

    NASA Technical Reports Server (NTRS)

    Wang, Q. Daniel

    1997-01-01

    We made the first measurement of the extragalactic 0.7 keV background. We detected the X-ray shadow of a neutral gas cloud in the Magellanic Bridge. We further constrained the point-like source contribution based on the mean spectrum of detected sources and on our early autocorrelation function analysis of the background. We find that our measurement extragalactic background intensity is significantly greater than the total point-like source contribution expected if sources are responsible for all the observed background intensity in the 1-2 keV range. For a further confirmation of the theoretical prediction of the hot intergalactic medium, we have conducted a pilot project to search for enhanced X-ray-emitting features near rich clusters of galaxies. We have reported the discovery of an elongated complex of extended X-ray-emitting objects in and around the galaxy cluster A2125, based on an archival deep ROSAT/PSPC observation. Using multicolor optical imaging of galaxies in the field, we find that this complex represents a hierarchical superstructure spanning approx. 11 Mpc at the redshift approx. 0.247. The multiple peak X-ray morphology and large blue galaxy fraction of A2125 indicate that the cluster is undergoing a coalescence of subunits. The superstructure contains two additional clusters, projected at distances of only 3 and 4.3 Mpc from A2125. The most interesting feature is, however, the low-surface-brightness X-ray emission from a moderate galaxy concentration away from individual clusters. The emission likely arises in a hot (approx. 10(exp 7) K) intergalactic medium, as predicted in N-body/hydro simulations of structure formation. These results demonstrate the potential of X-ray observations as a powerful tool to study the large-scale structure of the universe.

  5. An X-ray spectral model for clumpy tori in active galactic nuclei

    SciTech Connect

    Liu, Yuan; Li, Xiaobo E-mail: lixb@ihep.ac.cn

    2014-05-20

    We construct an X-ray spectral model for the clumpy torus in an active galactic nucleus (AGN) using Geant4, which includes the physical processes of the photoelectric effect, Compton scattering, Rayleigh scattering, γ conversion, fluorescence line, and Auger process. Since the electrons in the torus are expected to be bounded instead of free, the deviation of the scattering cross section from the Klein-Nishina cross section has also been included, which changes the X-ray spectra by up to 25% below 10 keV. We have investigated the effect of the clumpiness parameters on the reflection spectra and the strength of the fluorescent line Fe Kα. The volume filling factor of the clouds in the clumpy torus only slightly influences the reflection spectra, however, the total column density and the number of clouds along the line of sight significantly change the shapes and amplitudes of the reflection spectra. The effect of column density is similar to the case of a smooth torus, while a small number of clouds along the line of sight will smooth out the anisotropy of the reflection spectra and the fluorescent line Fe Kα. The smoothing effect is mild in the low column density case (N {sub H} = 10{sup 23} cm{sup –2}), whereas it is much more evident in the high column density case (N {sub H} = 10{sup 25} cm{sup –2}). Our model provides a quantitative tool for the spectral analysis of the clumpy torus. We suggest that the joint fits of the broad band spectral energy distributions of AGNs (from X-ray to infrared) should better constrain the structure of the torus.

  6. X-Ray Spectral and Temporal Analysis of Narrow Line Seyfert 1 Galaxy Was 61

    NASA Astrophysics Data System (ADS)

    Dou, Liming; Wang, Ting-Gui; Ai, Yanli; Yuan, Weimin; Zhou, Hongyan; Dong, Xiao-Bo

    2016-03-01

    We present an analysis of spectrum and variability of the bright reddened narrow line Seyfert 1 galaxy Was 61 using 90 ks archival XMM-Newton data. The X-ray spectrum in 0.2–10 keV can be characterized by an absorbed power-law plus soft excess and an Fe Kα emission line. The power-law spectral index remains constant during the flux variation. The absorbing material is mildly ionized, with a column density of 3.2 × 1021 cm‑2, and does not appear to vary during the period of the X-ray observation. If the same material causes the optical reddening (E(B–V) ≃ 0.6 mag), it must be located outside the narrow line region with a dust-to-gas ratio similar to the average Galactic value. We detect significant variations of the Fe Kα line during the observational period. A broad Fe Kα line at ≃ 6.7 {{keV}} with a width of ∼0.6 keV is detected in the low flux segment of the first 40 ks exposure, and is absent in the spectra of other segments; a narrow Fe Kα emission line ∼6.4 keV with a width of ∼0.1 keV is observed in the subsequent 20 ks segment, which has a count rate 35% higher and is in the next day. We believe this is due to the change in geometry and kinematics of the X-ray emitting corona. The temperature and flux of soft X-ray excess appear to correlate with the flux of the hard power-law component. Comptonization of disc photons by a warm and optically thick inner disk is preferred to interpret the soft excess, rather than the ionized reflection.

  7. X-Ray Spectral Components Observed in the Afterglow of GRB 130925A

    NASA Technical Reports Server (NTRS)

    Bellm, Eric C.; Barriere, Nicolas M.; Bhalerao, Varun; Boggs, Steven E.; Cenko, S. Bradley; Christensen, Finn E.; Craig, William W.; Forster, Karl; Fryer, Chris L.; Hailey, Charles J.; Harrison, Fiona A.; Horesh, Assaf; Kouveliotou, Chryssa; Madsen, Kristin K.; Miller, Jon M.; Ofek, Eran O.; Perley, Daniel A.; Rana, Vikram R.; Miller, Jon M.; Stern, Daniel; Tomsick, John A.; Zhang, William W.

    2014-01-01

    We have identified spectral features in the late-time X-ray afterglow of the unusually long, slow-decaying GRB 130925A using NuSTAR, Swift/X-Ray Telescope, and Chandra. A spectral component in addition to an absorbed power law is required at greater than 4 less than 1 significance, and its spectral shape varies between two observation epochs at 2 x 10 (sup 5) and 10 (sup 6) seconds after the burst. Several models can fit this additional component, each with very different physical implications. A broad, resolved Gaussian absorption feature of several kiloelectronvolts width improves the fit, but it is poorly constrained in the second epoch. An additive blackbody or second power-law component provide better fits. Both are challenging to interpret: the blackbody radius is near the scale of a compact remnant (10 (sup 8) centimeters), while the second power-law component requires an unobserved high-energy cutoff in order to be consistent with the non-detection by Fermi/Large Area Telescope.

  8. THE NEXT GENERATION ATLAS OF QUASAR SPECTRAL ENERGY DISTRIBUTIONS FROM RADIO TO X-RAYS

    SciTech Connect

    Shang Zhaohui; Li Jun; Xie Yanxia; Brotherton, Michael S.; Cales, Sabrina L.; Dale, Daniel A.; Runnoe, Jessie C.; Kelly, Benjamin J.; Wills, Beverley J.; Wills, D.; Green, Richard F.; Nemmen, Rodrigo S.; Ganguly, Rajib; Hines, Dean C.; Kriss, Gerard A.; Tang, Baitian

    2011-09-01

    We have produced the next generation of quasar spectral energy distributions (SEDs), essentially updating the work of Elvis et al. by using high-quality data obtained with several space- and ground-based telescopes, including NASA's Great Observatories. We present an atlas of SEDs of 85 optically bright, non-blazar quasars over the electromagnetic spectrum from radio to X-rays. The heterogeneous sample includes 27 radio-quiet and 58 radio-loud quasars. Most objects have quasi-simultaneous ultraviolet-optical spectroscopic data, supplemented with some far-ultraviolet spectra, and more than half also have Spitzer mid-infrared Infrared Spectrograph spectra. The X-ray spectral parameters are collected from the literature where available. The radio, far-infrared, and near-infrared photometric data are also obtained from either the literature or new observations. We construct composite SEDs for radio-loud and radio-quiet objects and compare these to those of Elvis et al., finding that ours have similar overall shapes, but our improved spectral resolution reveals more detailed features, especially in the mid- and near-infrared.

  9. X-RAY SPECTRAL COMPONENTS OBSERVED IN THE AFTERGLOW OF GRB130925A

    SciTech Connect

    Bellm, Eric C.; Forster, Karl; Harrison, Fiona A.; Madsen, Kristin K.; Perley, Daniel A.; Rana, Vikram R.; Barrire, Nicolas M.; Boggs, Steven E.; Craig, William W.; Bhalerao, Varun; Cenko, S. Bradley; Christensen, Finn E.; Fryer, Chris L.; Hailey, Charles J.; Horesh, Assaf; Ofek, Eran O.; Kouveliotou, Chryssa; Reynolds, Stephen P.; Stern, Daniel; and others

    2014-04-01

    We have identified spectral features in the late-time X-ray afterglow of the unusually long, slow-decaying GRB130925A using NuSTAR, Swift/X-Ray Telescope, and Chandra. A spectral component in addition to an absorbed power law is required at >4? significance, and its spectral shape varies between two observation epochs at 2 10{sup 5} and 10{sup 6}s after the burst. Several models can fit this additional component, each with very different physical implications. A broad, resolved Gaussian absorption feature of several keV width improves the fit, but it is poorly constrained in the second epoch. An additive blackbody or second power-law component provide better fits. Both are challenging to interpret: the blackbody radius is near the scale of a compact remnant (10{sup 8}cm), while the second power-law component requires an unobserved high-energy cutoff in order to be consistent with the non-detection by Fermi/Large Area Telescope.

  10. X-RAY SPECTRAL STATE IS NOT CORRELATED WITH LUMINOSITY IN HOLMBERG II X-1

    SciTech Connect

    Grise, F.; Kaaret, P.; Feng, H.; Kajava, J. J. E.; Farrell, S. A.

    2010-12-01

    The ultraluminous X-ray source (ULX) Holmberg II X-1 has been observed over four months in 2009/2010 by the Swift observatory. The source luminosity varied by a factor of up to 14, reaching a maximum 0.3-10 keV luminosity of {approx}3.0 x 10{sup 40} erg s{sup -1}. The spectral properties do not vary much over these four months, with only a slight monotonic increase of the hardness ratio with the count rate. This means that the erratic flaring activity of the source is not associated with spectral changes, as seen in other ULXs. Conversely, comparison with data obtained by Swift in 2006 shows a completely different picture: while at a luminosity also seen in the 2009/2010 data, the source appears with a hard spectrum. Thus, it appears that, as in Galactic black hole binaries, spectral states in this ULX are not determined only by the X-ray luminosity.

  11. Deep galaxy count predictions in the radio, infrared, and X-ray spectral bands

    NASA Technical Reports Server (NTRS)

    Treyer, Marie-Agnes; Silk, Joseph

    1993-01-01

    The existence of a dominant population of strongly evolving starburst sources at moderate redshift is a plausible explanation for the excess number of faint blue galaxies detected in deep sky surveys. Multiwavelength observations at faint magnitudes would allow the existence of such a population to be confirmed. We use observed luminosity correlations and physical properties of known starburst galaxies to predict their contribution to the deep radio, infrared, and X-ray counts, as well as to the diffuse extragalactic background radiation in these various spectral bands.

  12. Spectral X-Ray Diffraction using a 6 Megapixel Photon Counting Array Detector

    PubMed Central

    Muir, Ryan D.; Pogranichniy, Nicholas R.; Muir, J. Lewis; Sullivan, Shane Z.; Battaile, Kevin P.; Mulichak, Anne M.; Toth, Scott J.; Keefe, Lisa J.; Simpson, Garth J.

    2016-01-01

    Pixel-array array detectors allow single-photon counting to be performed on a massively parallel scale, with several million counting circuits and detectors in the array. Because the number of photoelectrons produced at the detector surface depends on the photon energy, these detectors offer the possibility of spectral imaging. In this work, a statistical model of the instrument response is used to calibrate the detector on a per-pixel basis. In turn, the calibrated sensor was used to perform separation of dual-energy diffraction measurements into two monochromatic images. Targeting applications include multi-wavelength diffraction to aid in protein structure determination and X-ray diffraction imaging.

  13. Spectral x-ray diffraction using a 6 megapixel photon counting array detector

    NASA Astrophysics Data System (ADS)

    Muir, Ryan D.; Pogranichniy, Nicholas R.; Muir, J. Lewis; Sullivan, Shane Z.; Battaile, Kevin P.; Mulichak, Anne M.; Toth, Scott J.; Keefe, Lisa J.; Simpson, Garth J.

    2015-03-01

    Pixel-array array detectors allow single-photon counting to be performed on a massively parallel scale, with several million counting circuits and detectors in the array. Because the number of photoelectrons produced at the detector surface depends on the photon energy, these detectors offer the possibility of spectral imaging. In this work, a statistical model of the instrument response is used to calibrate the detector on a per-pixel basis. In turn, the calibrated sensor was used to perform separation of dual-energy diffraction measurements into two monochromatic images. Targeting applications include multi-wavelength diffraction to aid in protein structure determination and X-ray diffraction imaging.

  14. Infrared to x-ray spectral energy distributions of high redshift quasars

    NASA Technical Reports Server (NTRS)

    Bechtold, Jill; Elvis, Martin; Fiore, Fabrizio; Kuhn, Olga; Cutri, Roc M.; Mcdowell, Jonathan C.; Rieke, Marcia; Siemiginowska, Aneta; Wilkes, Belinda J.

    1994-01-01

    We have observed 14 quasars with z greater than 2.8 with the ROSAT-PSPC, and detected 12 of them, including the z=4.11 quasar 0000-263. We present the first x-ray spectrum of a radio quiet quasar with z greater than 3, 1946+768. Its x-ray spectrum is consistent with a power law with spectral index alpha(sub E)=1.8(sup +2.1, sub -1.4) and no evidence for absorption in excess of the galactic column (alpha(sub E)=1.00(sup +0.28, sub -0.32) assuming N(sub H)=N(sub H)(Gal)). A Position Sensitive Proportional Counter (PSPC) hardness ratio is used to constrain the x-ray spectral properties of the quasars for which there were less than 100 photons detected. For the radio quiet quasars, (alpha(sub E)) approximately equals 1.2, if one assumes that there is no absorption in excess of the galactic column. We combine the x-ray data with new ground based optical and near-IR spectrophotometry obtained at the Steward 2.3 m and Multiple Mirror Telescope, and data from the literature. The spectral energy distributions are compared to those of low redshift objects. For the radio quiet quasars with z greater than 2.5, the mean (alpha(sub ox)) is approximately 1.8. This is larger than the mean for quasars with z less than 2.5, but consistent with the expected value for quasars with the high optical luminosities of the objects in this sample. For the radio-loud quasars, (alpha(sub ox)) is approximately 1.4, independent of redshift. This is smaller than the expected value for the optically luminous, high redshift objects in this sample, if they are mostly GHz peaked radio sources and hence comparable to steep-spectrum, compact radio sources at lower redshift. Finally, we compare the spectral energy distributions of two representative objects to the predicted spectrum of a thin accretion disk in the Kerr geometry, and discuss the uncertainties in deriving black hole masses and mass accretion rates.

  15. The X-ray spectrum and spectral energy distribution of FIRST J155633.8+351758: a LoBAL quasar with a probable polar outflow

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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 ? = 1.7 or flatter at a >99 per cent confidence for a neutral hydrogen absorber model). Absorption is present, with a column density a few times 1023 cm-2, with both partially ionized models and partially covering neutral hydrogen models providing good fits. We present several lines of argument that suggest the fraction of X-ray emissions associated with the radio jet is not large. We combine our Chandra data with observations from the literature to construct the spectral energy distribution of FIRST J1556+3517 from radio to X-ray energies. We make corrections for Doppler beaming for the pole-on radio jet, optical dust reddening and X-ray absorption, in order to recover a probable intrinsic spectrum. The quasar FIRST J1556+3517 seems to be an intrinsically normal radio-quiet quasar with a reddened optical/UV spectrum, a Doppler-boosted but intrinsically weak radio jet and an X-ray absorber not dissimilar from that of other broad absorption line quasars.

  16. Spectral and timing nature of the symbiotic X-ray binary 4U 1954+319: The slowest rotating neutron star in an X-ray binary system

    SciTech Connect

    Enoto, Teruaki; Corbet, Robin H. D.; Sasano, Makoto; Yamada, Shin'ya; Tamagawa, Toru; Makishima, Kazuo; Pottschmidt, Katja; Marcu, Diana; Fuerst, Felix; Wilms, Jörn

    2014-05-10

    The symbiotic X-ray binary (SyXB) 4U 1954+319 is a rare system hosting a peculiar neutron star (NS) and an M-type optical companion. Its ∼5.4 hr NS spin period is the longest among all known accretion-powered pulsars and exhibited large (∼7%) fluctuations over 8 yr. A spin trend transition was detected with Swift/BAT around an X-ray brightening in 2012. The source was in quiescent and bright states before and after this outburst based on 60 ks Suzaku observations in 2011 and 2012. The observed continuum is well described by a Comptonized model with the addition of a narrow 6.4 keV Fe-Kα line during the outburst. Spectral similarities to slowly rotating pulsars in high-mass X-ray binaries, its high pulsed fraction (∼60%-80%), and the location in the Corbet diagram favor high B-field (≳ 10{sup 12} G) over a weak field as in low-mass X-ray binaries. The observed low X-ray luminosity (10{sup 33}-10{sup 35} erg s{sup –1}), probable wide orbit, and a slow stellar wind of this SyXB make quasi-spherical accretion in the subsonic settling regime a plausible model. Assuming a ∼10{sup 13} G NS, this scheme can explain the ∼5.4 hr equilibrium rotation without employing the magnetar-like field (∼10{sup 16} G) required in the disk accretion case. The timescales of multiple irregular flares (∼50 s) can also be attributed to the free-fall time from the Alfvén shell for a ∼10{sup 13} G field. A physical interpretation of SyXBs beyond the canonical binary classifications is discussed.

  17. Spectral and Timing Nature of the Symbiotic X-Ray Binary 4U 1954+319: The Slowest Rotating Neutron Star in AN X-Ray Binary System

    NASA Technical Reports Server (NTRS)

    Enoto, Teruaki; Sasano, Makoto; Yamada, Shin'Ya; Tamagawa, Toru; Makishima, Kazuo; Pottschmidt, Katja; Marcu, Diana; Corbet, Robin H. D.; Fuerst, Felix; Wilms, Jorn

    2014-01-01

    The symbiotic X-ray binary (SyXB) 4U 1954+319 is a rare system hosting a peculiar neutron star (NS) and an M-type optical companion. Its approx. 5.4 hr NS spin period is the longest among all known accretion-powered pulsars and exhibited large (is approx. 7%) fluctuations over 8 yr. A spin trend transition was detected with Swift/BAT around an X-ray brightening in 2012. The source was in quiescent and bright states before and after this outburst based on 60 ks Suzaku observations in 2011 and 2012. The observed continuum is well described by a Comptonized model with the addition of a narrow 6.4 keV Fe-K alpha line during the outburst. Spectral similarities to slowly rotating pulsars in high-mass X-ray binaries, its high pulsed fraction (approx. 60%-80%), and the location in the Corbet diagram favor high B-field (approx. greater than 10(exp12) G) over a weak field as in low-mass X-ray binaries. The observed low X-ray luminosity (10(exp33)-10(exp35) erg s(exp-1)), probable wide orbit, and a slow stellar wind of this SyXB make quasi-spherical accretion in the subsonic settling regime a plausible model. Assuming a approx. 10(exp13) G NS, this scheme can explain the approx. 5.4 hr equilibrium rotation without employing the magnetar-like field (approx. 10(exp16) G) required in the disk accretion case. The timescales of multiple irregular flares (approx. 50 s) can also be attributed to the free-fall time from the Alfv´en shell for a approx. 10(exp13) G field. A physical interpretation of SyXBs beyond the canonical binary classifications is discussed.

  18. An UHV apparatus for X-ray resonant magnetic reflectivity in the hard X-ray range

    SciTech Connect

    Jaouen, N.; Wilhelm, F.; Rogalev, A.; Goulon, J.; Tonnerre, J.M.

    2004-05-12

    We present the development of a novel UHV compact reflectometer designed and developed for the investigation of magnetic properties of thin films at the ID12-E.S.R.F. beamline. This new instrument is dedicated to x-ray resonant magnetic reflectivity experiment from thin film or multilayered sample. We present the principles of this versatile and simple instrument. We report also the results of resonant magnetic reflectivity experiments carried out for the Fe/Ir multilayers. This will demonstrate the capability to record either angle or energy dependent measurements at the L edges of Ir simultaneously to the XMCD spectra.

  19. Predicted image quality of a CMOS APS X-ray detector across a range of mammographic beam qualities

    NASA Astrophysics Data System (ADS)

    Konstantinidis, A.

    2015-09-01

    Digital X-ray detectors based on Complementary Metal-Oxide- Semiconductor (CMOS) Active Pixel Sensor (APS) technology have been introduced in the early 2000s in medical imaging applications. In a previous study the X-ray performance (i.e. presampling Modulation Transfer Function (pMTF), Normalized Noise Power Spectrum (NNPS), Signal-to-Noise Ratio (SNR) and Detective Quantum Efficiency (DQE)) of the Dexela 2923MAM CMOS APS X-ray detector was evaluated within the mammographic energy range using monochromatic synchrotron radiation (i.e. 17-35 keV). In this study image simulation was used to predict how the mammographic beam quality affects image quality. In particular, the experimentally measured monochromatic pMTF, NNPS and SNR parameters were combined with various mammographic spectral shapes (i.e. Molybdenum/Molybdenum (Mo/Mo), Rhodium/Rhodium (Rh/Rh), Tungsten/Aluminium (W/Al) and Tungsten/Rhodium (W/Rh) anode/filtration combinations at 28 kV). The image quality was measured in terms of Contrast-to-Noise Ratio (CNR) using a synthetic breast phantom (4 cm thick with 50% glandularity). The results can be used to optimize the imaging conditions in order to minimize patient's Mean Glandular Dose (MGD).

  20. The Far-Infrared Spectral Energy Distributions of X-ray Selected Active Galaxies

    NASA Technical Reports Server (NTRS)

    Kuraszkiewicz, J. K.; Wilkes, B. J.; Hooper, E. J.

    2003-01-01

    This paper reports the ISO results on hard X-ray selected AGN which are less biased against red/obscured objects than other selection wavebands. We find that, as predicted, the IR continuum of these sources extends to redder sources than in optically/radio selected sample. This indicates that the latter samples miss a portion of the population which is fainter in the optical but can be easily picked up in the hard X-ray. The range of IR SEDs is roughly consistent with reddening of the IR continuum up to column densities of around 10(exp 23)/cu cm. Modeling of the full SED using dusty disk models demonstrated that varying the viewing angle can explain the observed SEDs, though rather large disks are required to fit the cooler, long wavelength emission. From the fits we can obtain estimates of the mass and inclination of the system.

  1. Spectral formation in accreting X-ray pulsars: bimodal variation of the cyclotron energy with luminosity

    NASA Astrophysics Data System (ADS)

    Becker, P. A.; Klochkov, D.; Schnherr, G.; Nishimura, O.; Ferrigno, C.; Caballero, I.; Kretschmar, P.; Wolff, M. T.; Wilms, J.; Staubert, R.

    2012-08-01

    Context. Accretion-powered X-ray pulsars exhibit significant variability of the cyclotron resonance scattering feature (CRSF) centroid energy on pulse-to-pulse timescales, and also on much longer timescales. Two types of spectral variability are observed. For sources in group 1, the CRSF energy is negatively correlated with the variable source luminosity, and for sources in group 2, the opposite behavior is observed. The physical basis for this bimodal behavior is currently not well understood. Aims: We explore the hypothesis that the accretion dynamics in the group 1 sources is dominated by radiation pressure near the stellar surface, and that Coulomb interactions decelerate the gas to rest in the group 2 sources. Methods: We derive a new expression for the critical luminosity, Lcrit, such that radiation pressure decelerates the matter to rest in sources with X-ray luminosity LX > Lcrit. The formula for Lcrit is based on a simple physical model for the structure of the accretion column in luminous X-ray pulsars that takes into account radiative deceleration, the energy dependence of the cyclotron cross section, the thermodynamics of the accreting gas, the dipole structure of the pulsar magnetosphere, and the diffusive escape of radiation through the column walls. We show that for typical neutron star parameters, Lcrit = 1.5 1037 B1216/15 erg s-1, where B12 is the surface magnetic field strength in units of 1012 G. Results: The formula for the critical luminosity is evaluated for five sources, using the maximum value of the CRSF centroid energy to estimate the surface magnetic field strength B12. The results confirm that the group 1 sources are supercritical (LX > Lcrit) and the group 2 sources are subcritical (LX < Lcrit), although the situation is less clear for those highly variable sources that cross over the line LX = Lcrit. We also explain the variation of the CRSF energy with luminosity as a consequence of the variation of the characteristic emission height. The sign of this dependence is opposite in the supercritical and subcritical cases, hence creating the observed bimodal behavior. Conclusions: We have developed a new model for the critical luminosity in accretion-powered X-ray pulsars that explains the bimodal dependence of the CRSF centroid energy on the X-ray luminosity LX. Our model provides a physical basis for the observed variation of the CRSF energy as a function of LX for both the group 1 (supercritical) and the group 2 (subcritical) sources as a result of the variation of the emission height in the column.

  2. The complex ion structure of warm dense carbon measured by spectrally resolved x-ray scattering

    SciTech Connect

    Kraus, D.; Barbrel, B.; Falcone, R. W.; Vorberger, J.; Helfrich, J.; Frydrych, S.; Ortner, A.; Otten, A.; Roth, F.; Schaumann, G.; Schumacher, D.; Siegenthaler, K.; Wagner, F.; Roth, M.; Gericke, D. O.; Wünsch, K.; Bachmann, B.; Döppner, T.; Bagnoud, V.; Blažević, A.; and others

    2015-05-15

    We present measurements of the complex ion structure of warm dense carbon close to the melting line at pressures around 100 GPa. High-pressure samples were created by laser-driven shock compression of graphite and probed by intense laser-generated x-ray sources with photon energies of 4.75 keV and 4.95 keV. High-efficiency crystal spectrometers allow for spectrally resolving the scattered radiation. Comparing the ratio of elastically and inelastically scattered radiation, we find evidence for a complex bonded liquid that is predicted by ab-initio quantum simulations showing the influence of chemical bonds under these conditions. Using graphite samples of different initial densities we demonstrate the capability of spectrally resolved x-ray scattering to monitor the carbon solid-liquid transition at relatively constant pressure of 150 GPa. Showing first single-pulse scattering spectra from cold graphite of unprecedented quality recorded at the Linac Coherent Light Source, we demonstrate the outstanding possibilities for future high-precision measurements at 4th Generation Light Sources.

  3. Extragalactic x ray source counts

    NASA Technical Reports Server (NTRS)

    Schmidt, Maarten

    1991-01-01

    Extragalactic x-ray source counts carry information about the luminosity function and cosmic evolution of galaxies, BL Lac objects, Seyfort galaxies, and quasars. We discuss two available x-ray source samples with complete optical identifications and redshifts. We find evidence for instrumental bias in the detection of clusters for cosmic evolution of quasars, and of absorption effects in low luminosity Seyfert galaxies. Modest spectral and density evolution of Seyfort galaxies would allow the soft x-ray background to be made up entirely of discrete sources. We present a source count prognosis for the Advanced X-ray Astrophysics Facility (AXAF) energy range 0.5 to 10 keV.

  4. Determination of electron energy, spectral width, and beam divergence at the exit window for clinical megavoltage x-ray beams

    PubMed Central

    Sawkey, D. L.; Faddegon, B. A.

    2009-01-01

    Monte Carlo simulations of x-ray beams typically take parameters of the electron beam in the accelerating waveguide to be free parameters. In this paper, a methodology is proposed and implemented to determine the energy, spectral width, and beam divergence of the electron source. All treatment head components were removed from the beam path, leaving only the exit window. With the x-ray target and flattener out of the beam, uncertainties in physical characteristics and relative position of the target and flattening filter, and in spot size, did not contribute to uncertainty in the energy. Beam current was lowered to reduce recombination effects. The measured dose distributions were compared with Monte Carlo simulation of the electron beam through the treatment head to extract the electron source characteristics. For the nominal 6 and 18 MV x-ray beams, the energies were 6.510.15 and 13.90.2 MeV, respectively, with the uncertainties resulting from uncertainties in the detector position in the measurement and in the stopping power in the simulations. Gaussian spectral distributions were used, with full widths at half maximum ranging from 204% at 6 MV to 134% at 18 MV required to match the fall-off portion of the percent-depth ionization curve. Profiles at the depth of maximum dose from simulations that used the manufacturer-specified exit window geometry and no beam divergence were 23 cm narrower than measured profiles. Two simulation configurations yielding the measured profile width were the manufacturer-specified exit window thickness with electron source divergences of 3.3 at 6 MV and 1.8 at 18 MV and an exit window 40% thicker than the manufacturers specification with no beam divergence. With the x-ray target in place (and no flattener), comparison of measured to simulated profiles sets upper limits on the electron source divergences of 0.2 at 6 MV and 0.1 at 18 MV. A method of determining source characteristics without mechanical modification of the treatment head, and therefore feasible in clinics, is presented. The energies and spectral widths determined using this method agree with those determined with only the exit window in the beam path. PMID:19378730

  5. Correlated Temporal and Spectral Variability in Neutron Star and Black Hole X-Ray Binaries

    NASA Technical Reports Server (NTRS)

    Swank, J.

    2006-01-01

    The variability of neutron star and black hole X-ray sources has several dimensions, because of the roles played by different important time-scales. The variations on time scales of hours, weeks, and months, ranging from 50% to orders of magnitude, arise out of changes in the flow in the disk. The most important driving forces for those changes are probably various possible instabilities in the disk, though there may be effects with other dominant causes. The changes in the rate of flow appear to be associated with changes in the flow's configuration, as the accreting material approaches the compact object, for there are generally correlated changes in both the X-ray spectra and the character of the faster temporal variability. There has been a lot of progress in tracking these correlations, both for Z and Atoll neutron star low-mass X-ray binaries, and for black hole binaries. I will discuss these correlations and what they tell us about the physical states of the systems.

  6. Analysis of nuclear materials by energy dispersive x-ray fluorescence and spectral effects of alpha decay

    SciTech Connect

    Worley, Christopher G

    2009-01-01

    Energy dispersive X-ray fluorescence (EDXRF) spectra collected from alpha emitters are complicated by artifacts inherent to the alpha decay process, particularly when using portable instruments. For example, {sup 239}Pu EDXRF spectra exhibit a prominent uranium L X-ray emission peak series due to sample alpha decay rather than source-induced X-ray fluorescence. A portable EDXRF instrument was used to collect spectra from plutonium, americium, and a Pu-contaminated steel sample. The plutonium sample was also analyzed by wavelength dispersive XRF to demonstrate spectral differences observed when using these very different instruments.

  7. Multilayer X-ray mirrors for the (4.4-5)-nm carbon-window spectral region

    SciTech Connect

    Andreev, S. S.; Barysheva, M. M.; Vainer, Yu. A.; Gaikovich, P. K.; Pariev, D. E. Pestov, A. E.; Salashchenko, N. N.; Chkhalo, N. I.

    2013-05-15

    Cr/C-based multilayer X-ray mirrors intended for the reflection of X-ray radiation in the 'carbon-window' spectral region ({lambda} = 4.4-5 nm) are fabricated and studied. The structures are formed by magnetron sputtering at different deposition parameters. Under normal incidence, record reflection coefficients up to 15% are reached. The structural parameters of the mirrors are investigated by reflectometry at wavelengths of 0.154 and 4.47 nm.

  8. Multi-Spectral Solar Telescope Array. II - Soft X-ray/EUV reflectivity of the multilayer mirrors

    NASA Technical Reports Server (NTRS)

    Barbee, Troy W., Jr.; Weed, J. W.; Hoover, Richard B.; Allen, Maxwell J.; Lindblom, Joakim F.; O'Neal, Ray H.; Kankelborg, Charles C.; Deforest, Craig E.; Paris, Elizabeth S.; Walker, Arthur B. C., Jr.

    1991-01-01

    The Multispectral Solar Telescope Array is a rocket-borne observatory which encompasses seven compact soft X-ray/EUV, multilayer-coated, and two compact far-UV, interference film-coated, Cassegrain and Ritchey-Chretien telescopes. Extensive measurements are presented on the efficiency and spectral bandpass of the X-ray/EUV telescopes. Attention is given to systematic errors and measurement errors.

  9. N132D: Chandra and XMM-Newton X-ray Imaging and Spectral Analysis

    NASA Astrophysics Data System (ADS)

    Plucinsky, Paul; Foster, Adam; Gaetz, Terrance; Jerius, Diab; Patnaude, Daniel; Edgar, Richard; Smith, Randall; Blair, William

    2015-09-01

    We present the results of an analysis of the archival XMM-Newton EPIC data (203ks for pn and 556/574ks for MOS1/MOS2) and the Chandra X-ray Observatory ACIS data (89ks) of the brightest X-ray supernova remnant (SNR) in the Large Magellanic Cloud (LMC) N132D. N132D has been classified as an ``O-rich'' remnant based on the UV and optical spectra which show emission from C, O, Ne, Mg, and Si.These spectra of the central optical knots do notshow any emission from elements with Z higher than Si, yet the nulceosynthesis models predict significant quantities of these higher Z elements. Our spectral analysis of the deep XMM data clearly shows emission lines from S, Ar, Ca, and Fe, with indications of other possible features between Ca and Fe. We use a combination of the high resolution images from Chandra and the sensitive spectra from XMM to disentangle the emission from swept-up interstellar material and a possiblehot ejecta component. We interpret these results in the context of a 3,000 year old remnant from a massive progenitor that has exploded into a cavity created by the progenitor. We also present simulations of the Athena X-ray Integral Field Unit (X-IFU) spectrum of N132D. We use themodel spectrum developed by the International Astronomical Consortium for High Energy Calibration (IACHEC) based on the high-resolution data acquired by the Reflection Gratings Spectrometer (RGS) on XMM as the input spectrumfor the X-IFU simulations.

  10. Spectral softening in the X-RAY afterglow of GRB 130925A as predicted by the dust scattering model

    SciTech Connect

    Zhao, Yi-Nan; Shao, Lang

    2014-07-01

    Gamma-ray bursts (GRBs) usually occur in a dense star-forming region with a massive circumburst medium. The small-angle scattering of intense prompt X-ray emission off the surrounding dust grains will have observable consequences and sometimes can dominate the X-ray afterglow. In most of the previous studies, only the Rayleigh-Gans (RG) approximation is employed for describing the scattering process, which works accurately for the typical size of grains (with radius of a ≤ 0.1 μm) in the diffuse interstellar medium. When the size of the grains may significantly increase, as in a more dense region where GRBs would occur, the RG approximation may not be valid enough for modeling detailed observational data. In order to study the temporal and spectral properties of the scattered X-ray emission more accurately with potentially larger dust grains, we provide a practical approach using the series expansions of anomalous diffraction (AD) approximation based on the complicated Mie theory. We apply our calculations to understand the puzzling X-ray afterglow of recently observed GRB 130925A that showed a significant spectral softening. We find that the X-ray scattering scenarios with either AD or RG approximation adopted could well reproduce both the temporal and spectral profile simultaneously. Given the plateau present in the early X-ray light curve, a typical distribution of smaller grains as in the interstellar medium would be suggested for GRB 130925A.

  11. The radio/X-ray correlation in Cyg X-3 and the nature of its hard spectral state

    NASA Astrophysics Data System (ADS)

    Zdziarski, Andrzej A.; Segreto, Alberto; Pooley, Guy G.

    2016-02-01

    We study the radio/X-ray correlation in Cyg X-3. It has been known that the soft and hard X-ray fluxes in the hard spectral state are correlated positively and negatively, respectively, with the radio flux. We show that this implies that the observed ˜1-100 keV flux (which is a fair approximation to the bolometric flux) is completely uncorrelated with the radio flux. We can recover a positive correlation (seen in other sources and expected theoretically) if the soft X-rays are strongly absorbed by a local medium. Then, however, the intrinsic X-ray spectrum of Cyg X-3 in its hard state becomes relatively soft, similar to that of an intermediate spectral state of black hole binaries, but not to their true hard state. We also find the radio spectra in the hard state of Cyg X-3 are hard on average, and the flux distributions of the radio emission and soft X-rays can be described by sums of two lognormal functions. We compare Cyg X-3 with other X-ray binaries using colour-colour, colour-Eddington ratio and Eddington ratio-radio flux diagrams. We find Cyg X-3 to be spectrally most similar to GRS 1915+105, except that Cyg X-3 is substantially more radio loud, which appears to be due to its jet emission enhanced by interaction with the powerful stellar wind from the Wolf-Rayet donor.

  12. Investigation of X-ray spectral response of D-T fusion produced neutron irradiated PIPS detectors for plasma X-ray diagnostics

    NASA Astrophysics Data System (ADS)

    Vigneshwara Raja, P.; Narasimha Murty, N. V. L.; Rao, C. V. S.; Abhangi, Mitul

    2015-10-01

    This paper describes the fusion-produced neutron irradiation induced changes in the X-ray spectral response of commercially available Passivated Implanted Planar Silicon (PIPS) detectors using the accelerator based D-T generator. After 14.1 MeV neutron irradiation up to a fluence of 3.6 1010 n/cm2, the energy resolution (i.e. FWHM) of the detectors at room temperature is found to degrade by about 3.8 times that of the pre-irradiated value. From the X-ray spectral characteristics, it has been observed that the room temperature spectral response of PIPS detectors is too poor even at low neutron fluences. Irradiation is also carried out with Am-Be neutron source for studying the effect of scattered neutrons from the reactor walls on the detector performance. Comparative studies of the damage caused by 14.1 MeV neutrons and Am-Be source produced neutrons at the same neutron fluence are carried out by analyzing the irradiated detector characteristics. The degradation in the energy resolution of the detectors is attributed to the radiation induced changes in the detector leakage current. No considerable changes in the full depletion voltage and the effective doping concentration up to the neutron fluence of 3.6 1010 n/cm2, are observed from the measured C-V characteristics. Partial recovery of the neutron irradiated detector characteristics is discussed.

  13. The Multi-Spectral Solar Telescope Array. II - Soft X-ray/EUV reflectivity of the multilayer mirrors

    NASA Technical Reports Server (NTRS)

    Barbee, Troy W., Jr.; Weed, J. W.; Hoover, Richard B. C., Jr.; Allen, Max J.; Lindblom, Joakim F.; O'Neal, Ray H.; Kankelborg, Charles C.; Deforest, Craig E.; Paris, Elizabeth S.; Walker, Arthur B. C.

    1992-01-01

    We have developed seven compact soft X-ray/EUV (XUV) multilayer coated and two compact FUV interference film coated Cassegrain and Ritchey-Chretien telescopes for a rocket borne observatory, the Multi-Spectral Solar Telescope Array. We report here on extensive measurements of the efficiency and spectral bandpass of the XUV telescopes carried out at the Stanford Synchrotron Radiation Laboratory.

  14. THE FIRST HARD X-RAY POWER SPECTRAL DENSITY FUNCTIONS OF ACTIVE GALACTIC NUCLEUS

    SciTech Connect

    Shimizu, T. Taro; Mushotzky, Richard F.

    2013-06-10

    We present results of our power spectral density (PSD) analysis of 30 active galactic nuclei (AGNs) using the 58 month light curves from Swift's Burst Alert Telescope (BAT) in the 14-150 keV band. PSDs were fit using a Monte Carlo based algorithm to take into account windowing effects and measurement error. All but one source were found to be fit very well using an unbroken power law with a slope of {approx} - 1, consistent at low frequencies with previous studies in the 2-10 keV band, with no evidence of a break in the PSD. For five of the highest signal-to-noise ratio sources, we tested the energy dependence of the PSD and found no significant difference in the PSD at different energies. Unlike previous studies of X-ray variability in AGNs, we do not find any significant correlations between the hard X-ray variability and different properties of the AGN including luminosity and black hole mass. The lack of break frequencies and correlations seem to indicate that AGNs are similar to the high state of Galactic black holes.

  15. Suzaku Spectral Study of the Galactic Ridge X-Ray Emission

    NASA Astrophysics Data System (ADS)

    Ebisawa, K.; Yamauchi, S.; Tanaka, Y.; Koyama, K.; Suzaku Team

    We have observed a typical Galactic plane blank field with Suzaku for 100 ksec to carry out spectral study of the Galactic Ridge X-ray Emission (GRXE). The field had been previously studied with Chandra, and is known to be devoid of bright X-ray point sources. We were able to resolve, for the first time, three narrow iron K-emission lines from low-ionized (6.4 keV), helium-like (6.67 keV), and hydrogenic ions (7.0 keV). These line features constrain the GRXE emission mechanisms. The cosmic-ray ion charge exchange model or the non-ionization equirribrium (NIE) plasma model are very unlikely, since they require either broad emission lines or lines at intermediate ionization states. We were able to precisely measure the absolute GRXE flux thanks to the low background and small stray-light contamination of Suzaku. Excluding point sources brighter than 2 10-13 ergs s-1 cm-2 (2-10 keV), only 10 the Chandra point sources brighter than 3 10-15 ergs s-1 cm-2.

  16. Final Report of B548129: Spectral Analysis of Soft X-Ray Data from NSTX

    SciTech Connect

    Lepson, J K; Jernigan, J G; Beiersdorfer, P

    2007-11-09

    We present a summary of work performed under subcontract B548129 'Spectral Analysis of Soft X-Ray Data from NSTX'. This summary is comprised of papers and poster presentations prepared under this subcontract. The X-ray and Extreme Ultraviolet Spectrometer (XEUS) has been used to monitor the line emission from various impurity ions on NSTX, in particular the K-shell emission of helium-like and hydrogen-like B, C, N, and O. While C VI typically dominates the spectrum, unusually strong emission from N VII has been observed in multiple discharges during the past run campaign. In this case, the nitrogen concentration can exceed that of carbon by an order of magnitude. Time-dependent measurements show that the nitrogen concentration builds up over the course of the discharge and coincides with a build up of boron. In a few cases we observed several unknown lines. These are clearly lines from heavy impurities, possibly molybdenum. Some of these lines can be explained by the emission from Ti XIII.

  17. Short-range order in mesoscale systems probed by X-ray grating interferometry

    NASA Astrophysics Data System (ADS)

    Prade, F.; Yaroshenko, A.; Herzen, J.; Pfeiffer, F.

    2015-12-01

    The dark-field signal obtained with X-ray grating interferometry combines the object's small-angle scattering auto-correlation function with an imaging modality. Here we report on the measurement of such correlation functions with a laboratory X-ray system. By fitting a theoretical model to the data we are able to determine the size and short-range order of the scattering structures. Thus, a quantitative interpretation of the dark-field signal is also possible with a polychromatic and divergent beam. We further show how the microscopic information is obtained for mesoscale objects and can be represented in order to overlay the microstructural information on top of the macrostructure. The quantitative real-space information on the form and structure factor makes this technique highly attractive for materials science as it allows one to study these properties in the laboratory.

  18. Origin of the Characteristic X-ray Spectral Variation of the Narrow Line Seyfert 1 Galaxies

    NASA Astrophysics Data System (ADS)

    Ebisawa, K.; Yamasaki, H.; Mizumoto, M.; Sameshima, H.

    2015-07-01

    We have proposed the Variable Double Partial Covering (VDPC) model to explain characteristic spectral variability of MCG-6-30-15 (Miyakawa et al. 2012), 1H0707-495 (Mizumoto, Ebisawa and Sameshima 2014) and other 20 Seyfert galaxies (Iso et al. 2015). In this model, observed flux/spectral variations below 10 keV within a day are primarily caused by change of the partial covering fraction of the central X-ray source by patchy absorbing clouds with internal structure. Here, we found the VDPC model is also successful to explain spectral variations as well as Root Mean Square (RMS) spectra of IRAS 13224-3809, Mrk 335 and Ark 564 in the 0.5 -10 keV. In addition to the well-known significant drop in the iron K-band, we occasionally found such intriguing iron L-peaks in the RMS spectra of 1H0707-495 and IRAS 13224-$3809, that appear when iron L-absorption edges are particularly deep. This feature is naturally explained with the VDPC model, where the fluxes of the direct component (without absorption edges) and the absorbed component (with absorption edges) exhibit anti-correlation while the sum is hardly variable. The fractional variation thus peaks at the energy where the flux separation between the two spectral components is the widest, corresponding to the iron L-edge.

  19. Detection of faint X-ray spectral features using wavelength, energy, and spatial discrimination techniques

    NASA Astrophysics Data System (ADS)

    Hudson, L. T.; Gillaspy, J. D.; Pomeroy, J. M.; Szabo, C. I.; Tan, J. N.; Radics, B.; Takacs, E.; Chantler, C. T.; Kimpton, J. A.; Kinnane, M. N.; Smale, L. F.

    2007-09-01

    We report here our methods and results of measurements of very low-signal X-ray spectra produced by highly charged ions in an electron beam ion trap (EBIT). A megapixel Si charge-coupled device (CCD) camera was used in a direct-detection, single-photon-counting mode to image spectra with a cylindrically bent Ge(2 2 0) crystal spectrometer. The resulting wavelength-dispersed spectra were then processed using several intrinsic features of CCD images and image-analysis techniques. We demonstrate the ability to clearly detect very faint spectral features that are on the order of the noise due to cosmic-ray background signatures in our images. These techniques remove extraneous signal due to muon tracks and other sources, and are coupled with the spectrometer wavelength dispersion and atomic-structure calculations of hydrogen-like Ti to identify the energy of a faint line that was not in evidence before applying the methods outlined here.

  20. FIRST EVIDENCE FOR SPECTRAL STATE TRANSITIONS IN THE ESO 243-49 HYPERLUMINOUS X-RAY SOURCE HLX-1

    SciTech Connect

    Godet, O.; Barret, D.; Webb, N. A.; Farrell, S. A.; Gehrels, N.

    2009-11-10

    The brightest ultra-luminous X-ray source, ESO 243-49 HLX-1, with a 0.2-10 keV X-ray luminosity of up to 10{sup 42} erg s{sup -1}, provides the strongest evidence to date for the existence of intermediate mass black holes (BHs). Although small-scale X-ray spectral variability has already been demonstrated, we have initiated a monitoring campaign with the X-ray Telescope (XRT) onboard the Swift satellite to search for luminosity-related spectral changes and to compare its behavior with the better-studied stellar mass BHs. In this Letter, we report a drop in the XRT count rate by a factor of approx8 which occurred simultaneously with a hardening of the X-ray spectrum. A second observation found that the source had re-brightened by a factor of approx21 which occurred simultaneously with a softening of the X-ray spectrum. This may be the first evidence for a transition between the low/hard and high/soft states.

  1. X-ray and Ultraviolet Spectral Evolution of LMC X-3 During Normal and Anomalous Low States

    NASA Astrophysics Data System (ADS)

    Torpin, Trevor; Boyd, P. T.; Smale, A. P.

    2014-01-01

    The bright black-hole X-ray binary LMC X-3 is a lower-mass high-mass X-ray binary with a 1.7 day orbital period. Both the X-ray source and its bright optical/UV companion show non-periodic high amplitude variability on timescales much longer than this (100-300 days). Previous observations do not present a clean picture of whether Roche-lobe overflow or wind accretion is the dominant mechanism driving this dramatic long-term variability. RXTE monitoring has recently revealed that LMC X-3 undergoes surprising anomalous low states (ALSs), during which the X-ray source is virtually indistinguishable from background, and stays low for three to six months at a time (Smale & Boyd 2012). The cause of these ALSs is not known. NASA's Swift telescope is uniquely capable of shedding light on this mystery by providing simultaneous X-ray, UV, and optical observations of the source during its normal long-term variability. Swift has obtained simultaneous multiwavelength data at a variety of X-ray fluxes while the system was displaying its normal variability state, as well as dense monitoring during an ALS and during a recent normal low state. Comparison of X-ray spectral modeling with the UV variability offers the best chance to disentangle the various sources of UV radiation in the system. We present the results of spectral fitting of the Swift XRT and, when available, XMM/Newton spectra which probe the accretion state of the black hole. We compare these with the UV flux arising from the stellar surface and outer accretion disk, searching for correlations and lags that could reveal whether a substantial fraction of the UV flux is due to reprocessing of X-rays within the system, or arises from another mechanism.

  2. The X-ray spectra of galaxies. II - Average spectral properties and emission mechanisms

    NASA Technical Reports Server (NTRS)

    Kim, D.-W.; Fabbiano, G.; Trinchieri, G.

    1992-01-01

    The Imaging Proportional Counter data in the Einstein database is used to study the X-ray spectra of normal galaxies. The X-ray emission temperature of spirals is found to be higher on the average than that of ellipticals. This supports the idea that accreting binaries are a major source of X-rays in spirals, while a hot interstellar medium (ISM) is present in ellipticals. The X-ray spectra of Sa galaxies are intermediate between those of ellipticals and spirals, suggesting that these galaxies contain hot gaseous emission as well as emission from accreting binaries. In E and SO galaxies the emission temperature becomes higher with a decreasing X-ray to optical luminosity ratio, which suggests that the emission of X-ray faint early-type galaxies consists of a large evolved stellar component, while the gaseous emission becomes dominant in X-ray brighter galaxies. The group with the lowest X-ray to optical ratio does not follow this trend; in these galaxies a very soft X-ray component, amounting to about half the total X-ray emission, is found in addition to the hard X-ray component. Possible explanations are integrated emission of M stars and a relatively cool ISM. A very soft component is also found in several spiral galaxies. This may indicate that some spirals contain hot gaseous components similar to those seen in NGC 253 and M82.

  3. Single-step, quantitative x-ray differential phase contrast imaging using spectral detection in a coded aperture setup

    NASA Astrophysics Data System (ADS)

    Das, Mini; Liang, Zhihua

    2015-03-01

    In this abstract we describe the first non-interferometric x-ray phase contrast imaging (PCI) method that uses only a single-measurement step to retrieve with quantitative accuracy absorption, phase and differential phase. Our approach is based on utilizing spectral information from photon counting spectral detectors in conjunction with a coded aperture PCI setting to simplify the x-ray "phase problem" to a one-step method. The method by virtue of being single-step with no motion of any component for a given projection image has significantly high potential to overcome the barriers currently faced by PCI.

  4. Discovery of Spatial and Spectral Structure in the X-Ray Emission from the Crab Nebula

    NASA Technical Reports Server (NTRS)

    Weisskopf, Martin C.; Hester, J. Jeff; Tennant, Allyn F.; Elsner, Ronald F.; Schulz, Norbert S.; Marshall, Herman L.; Karovska, Margarita; Nichols, Joy S.; Swartz, Douglas A.; Kolodziejczak, Jeffery J.

    2000-01-01

    The Chandra X-Ray Observatory observed the Crab Nebula and pulsar during orbital calibration. Zeroth-order images with the High-Energy Transmission Grating (HETG) readout by the Advanced Charge Coupled Devices (CCD) Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of X-ray structure at a resolution comparable to that of the best ground-based visible-light observations. The HETG-ACIS-S images reveal, for the first time, an X-ray inner ring within the X-ray torus, the suggestion of a hollow-tube structure for the torus, and X-ray knots along the inner ring and (perhaps) along the inward extension of the X-ray jet. Although complicated by instrumental effects and the brightness of the Crab Nebula, the spectrometric analysis shows systematic variations of the X-ray spectrum throughout the nebula.

  5. Discovery of Spatial and Spectral Structure in the X-Ray Emission from the Crab Nebula.

    PubMed

    Weisskopf; Hester; Tennant; Elsner; Schulz; Marshall; Karovska; Nichols; Swartz; Kolodziejczak; O'Dell

    2000-06-20

    The Chandra X-Ray Observatory observed the Crab Nebula and pulsar during orbital calibration. Zeroth-order images with the High-Energy Transmission Grating (HETG) readout by the Advanced CCD Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of X-ray structure at a resolution comparable to that of the best ground-based visible-light observations. The HETG-ACIS-S images reveal, for the first time, an X-ray inner ring within the X-ray torus, the suggestion of a hollow-tube structure for the torus, and X-ray knots along the inner ring and (perhaps) along the inward extension of the X-ray jet. Although complicated by instrumental effects and the brightness of the Crab Nebula, the spectrometric analysis shows systematic variations of the X-ray spectrum throughout the nebula. PMID:10859123

  6. A cascaded model of spectral distortions due to spectral response effects and pulse pileup effects in a photon-counting x-ray detector for CT

    SciTech Connect

    Cammin, Jochen E-mail: ktaguchi@jhmi.edu; Taguchi, Katsuyuki E-mail: ktaguchi@jhmi.edu; Xu, Jennifer; Barber, William C.; Iwanczyk, Jan S.; Hartsough, Neal E.

    2014-04-15

    Purpose: Energy discriminating, photon-counting detectors (PCDs) are an emerging technology for computed tomography (CT) with various potential benefits for clinical CT. The photon energies measured by PCDs can be distorted due to the interactions of a photon with the detector and the interaction of multiple coincident photons. These effects result in distorted recorded x-ray spectra which may lead to artifacts in reconstructed CT images and inaccuracies in tissue identification. Model-based compensation techniques have the potential to account for the distortion effects. This approach requires only a small number of parameters and is applicable to a wide range of spectra and count rates, but it needs an accurate model of the spectral distortions occurring in PCDs. The purpose of this study was to develop a model of those spectral distortions and to evaluate the model using a PCD (model DXMCT-1; DxRay, Inc., Northridge, CA) and various x-ray spectra in a wide range of count rates. Methods: The authors hypothesize that the complex phenomena of spectral distortions can be modeled by: (1) separating them into count-rate independent factors that we call the spectral response effects (SRE), and count-rate dependent factors that we call the pulse pileup effects (PPE), (2) developing separate models for SRE and PPE, and (3) cascading the SRE and PPE models into a combined SRE+PPE model that describes PCD distortions at both low and high count rates. The SRE model describes the probability distribution of the recorded spectrum, with a photo peak and a continuum tail, given the incident photon energy. Model parameters were obtained from calibration measurements with three radioisotopes and then interpolated linearly for other energies. The PPE model used was developed in the authors’ previous work [K. Taguchi et al., “Modeling the performance of a photon counting x-ray detector for CT: Energy response and pulse pileup effects,” Med. Phys. 38(2), 1089–1102 (2011)]. The agreement between the x-ray spectra calculated by the cascaded SRE+PPE model and the measured spectra was evaluated for various levels of deadtime loss ratios (DLR) and incident spectral shapes, realized using different attenuators, in terms of the weighted coefficient of variation (COV{sub W}), i.e., the root mean square difference weighted by the statistical errors of the data and divided by the mean. Results: At low count rates, when DLR < 10%, the distorted spectra measured by the DXMCT-1 were in agreement with those calculated by SRE only, with COV{sub W}'s less than 4%. At higher count rates, the measured spectra were also in agreement with the ones calculated by the cascaded SRE+PPE model; with PMMA as attenuator, COV{sub W} was 5.6% at a DLR of 22% and as small as 6.7% for a DLR as high as 55%. Conclusions: The x-ray spectra calculated by the proposed model agreed with the measured spectra over a wide range of count rates and spectral shapes. The SRE model predicted the distorted, recorded spectra with low count rates over various types and thicknesses of attenuators. The study also validated the hypothesis that the complex spectral distortions in a PCD can be adequately modeled by cascading the count-rate independent SRE and the count-rate dependent PPE.

  7. A cascaded model of spectral distortions due to spectral response effects and pulse pileup effects in a photon-counting x-ray detector for CT

    PubMed Central

    Cammin, Jochen; Xu, Jennifer; Barber, William C.; Iwanczyk, Jan S.; Hartsough, Neal E.; Taguchi, Katsuyuki

    2014-01-01

    Purpose: Energy discriminating, photon-counting detectors (PCDs) are an emerging technology for computed tomography (CT) with various potential benefits for clinical CT. The photon energies measured by PCDs can be distorted due to the interactions of a photon with the detector and the interaction of multiple coincident photons. These effects result in distorted recorded x-ray spectra which may lead to artifacts in reconstructed CT images and inaccuracies in tissue identification. Model-based compensation techniques have the potential to account for the distortion effects. This approach requires only a small number of parameters and is applicable to a wide range of spectra and count rates, but it needs an accurate model of the spectral distortions occurring in PCDs. The purpose of this study was to develop a model of those spectral distortions and to evaluate the model using a PCD (model DXMCT-1; DxRay, Inc., Northridge, CA) and various x-ray spectra in a wide range of count rates. Methods: The authors hypothesize that the complex phenomena of spectral distortions can be modeled by: (1) separating them into count-rate independent factors that we call the spectral response effects (SRE), and count-rate dependent factors that we call the pulse pileup effects (PPE), (2) developing separate models for SRE and PPE, and (3) cascading the SRE and PPE models into a combined SRE+PPE model that describes PCD distortions at both low and high count rates. The SRE model describes the probability distribution of the recorded spectrum, with a photo peak and a continuum tail, given the incident photon energy. Model parameters were obtained from calibration measurements with three radioisotopes and then interpolated linearly for other energies. The PPE model used was developed in the authors previous work [K. Taguchi , Modeling the performance of a photon counting x-ray detector for CT: Energy response and pulse pileup effects, Med. Phys. 38(2), 10891102 (2011)]. The agreement between the x-ray spectra calculated by the cascaded SRE+PPE model and the measured spectra was evaluated for various levels of deadtime loss ratios (DLR) and incident spectral shapes, realized using different attenuators, in terms of the weighted coefficient of variation (COVW), i.e., the root mean square difference weighted by the statistical errors of the data and divided by the mean. Results: At low count rates, when DLR < 10%, the distorted spectra measured by the DXMCT-1 were in agreement with those calculated by SRE only, with COVW's less than 4%. At higher count rates, the measured spectra were also in agreement with the ones calculated by the cascaded SRE+PPE model; with PMMA as attenuator, COVW was 5.6% at a DLR of 22% and as small as 6.7% for a DLR as high as 55%. Conclusions: The x-ray spectra calculated by the proposed model agreed with the measured spectra over a wide range of count rates and spectral shapes. The SRE model predicted the distorted, recorded spectra with low count rates over various types and thicknesses of attenuators. The study also validated the hypothesis that the complex spectral distortions in a PCD can be adequately modeled by cascading the count-rate independent SRE and the count-rate dependent PPE. PMID:24694136

  8. Extreme ultraviolet and soft x-ray spectral lines in Rb XXIX

    NASA Astrophysics Data System (ADS)

    Indu, Khatri; Arun, Goyal; Sunny, Aggarwal; A, K. Singh; Man, Mohan

    2016-03-01

    An extensive theoretical set of atomic data for Rb XXIX in a wide range with L-shell electron excitations to the M-shell has been reported. We have computed energy levels for the lowest 113 fine structure levels of Rb XXIX. The fully relativistic multiconfigurational Dirac–Fock method (MCDF) within the framework of Dirac–Coulomb Hamiltonian taking quantum electrodynamics (QED) and Breit corrections into account has been adopted for calculations. Radiative data are reported for electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions from the ground level, although calculations have been performed for a much larger number of levels. To assess the accuracy of results, we performed analogous calculations using flexible atomic code (FAC). Comparisons are made with existing available results and a good agreement has been achieved. Most of the wavelengths calculated lie in the soft x-ray (SXR) region. Lifetimes for all 113 levels have also been provided for the first time. Additionally, we have provided the spectra for allowed transitions from n = 2 to n = 3 within the x-ray region and also compared our SXR photon wavelengths with experimentally recognized wavelengths. We hope that our results will be beneficial in fusion plasma research and astrophysical applications.

  9. High Resolution Temporal and Spectral Monitoring of Eta Carinae's X-Ray Emission the June Eclipse

    NASA Technical Reports Server (NTRS)

    Corcoran, M. F.; Hamaguchi, K.; Henley, D.; Pittard, J. M.; Gull, T. R.; Davidson, K.; Swank, J. H.; Petre, R.; Ishibashi, K.

    2004-01-01

    The supermassive and luminous star Eta Carinae undergoes strong X-ray variations every 5.5 years when its 2-10 keV X-ray emission brightens rapidly with wild fluctuations before dropping by a factor of 100 to a minimum lasting 3 months. The most recent X-ray "eclipse" began in June 2003 and during this time Eta Carinae was intensely observed throughout the electromagnetic spectrum. Here we report the first results of frequent monitoring of the 2-10 keV band X-ray emission by the Rossi X-ray Timing Explorer along wit high resolution X-ray spectra obtained with the transmission gratings on the Chandra X-ray Observatory. We compare these observations to those results obtained during the previous X-ray eclipse in 1998, and interpret the variations in the X-ray brightness, in the amount of absorption, in the X-ray emission measure and in the K-shell emission lines in terms of a colliding wind binary model.

  10. Chandra X-ray Observations of Jovian Low-latitude Emissions: Morphological, Temporal, and Spectral Characteristics

    NASA Astrophysics Data System (ADS)

    Bhardwaj, A.; Elsner, R. F.; Gladstone, G. R.; Cravens, T. E.; Waite, J. H., Jr.; Branduardi-Raymont, G.; Ford, P.

    2004-11-01

    Chandra observed X-rays from Jupiter during 24-26 February 2003 for about 40 hours with the ACIS-S and HRC-I instruments. The analysis of Jovian low-latitude "disk" X-ray emissions are presented and compared with the high-latitude "auroral" emissions. We report the first Chandra ACIS-S measured X-ray spectrum (0.3-2 keV) of Jupiter's low-latitude disk. The disk X-ray emission is harder and extends to higher energies than the auroral spectrum. The temporal variation in the Jovian disk X-rays is on an average consistent with those in the solar X-rays observed by GOES, and TIMED/SEE. Contrary to the auroral X-rays, the disk emissions are uniformly distributed over the Jupiter; no indication of longitudinal dependence or correlation with surface magnetic field strength is visible. Also, unlike the 4020-min periodic oscillations seen in the auroral X-ray emissions, the disk emissions do not show any periodic oscillations. The disk spectrum seems to be consistent with resonant and fluorescent scattering of solar X-rays by the Jovian upper atmosphere. Jupiter's disk is found to be about 50% dimmer in soft X-rays in February 2003 compared that in December 2000, which is consistent with the decrease in solar activity. No evidence of lightning-induced X-rays is seen in the Chandra X-ray data. The Jovian disk spectra observed with Chandra-ACIS is stronger than that observed with XMM-Newton two months later during April 28-29, 2003. The XMM-Newton X-ray image of Jupiter shows evidence of limb darkening on the anti-sunward side as seen from Earth, as well as an asymmetry with respect to the subsolar point: suggesting a solar-driven process.

  11. BeppoSAX broad X-ray range observations of eta Carinae during high and low spectroscopic states

    NASA Astrophysics Data System (ADS)

    Viotti, R. F.; Antonelli, L. A.; Corcoran, M. F.; Damineli, A.; Grandi, P.; Muller, J. M.; Rebecchi, S.; Rossi, C.; Villada, M.

    2002-04-01

    We present BeppoSAX spectra of the extremely luminous and massive object eta Car observed in a very broad X-ray range (0.1-200 keV) during high state (December 1996) and egress from the last low state (March 1998). Both spectra are composed of at least two components, a soft one with kTs < 0.7 keV, and a hard with kTh =4.7 keV. We found in March 1998 a large flux defect in the 1.5-4 keV range, while the flux remained constant below 1.5 keV and above 5 keV. We attribute this defect to a x3.5 increase of the absorbing matter in front of the hard component, while its temperature and unabsorbed luminosity were nearly the same in the two epochs. In December 1996 the PDS X-ray flux in the 13-20 keV range is larger than the extrapolated hard spectrum, indicating the presence of an even harder additional component, which possibly declined during the March 1998 low state. Conversely, we find that at that time, the flux of the 6.7 keV iron line was 40% stronger. Coordinated optical and NIR spectroscopic observations indicate that in March 1998 eta Car was still in a state of low excitation of the emission line spectrum, with extended P Cygni absorptions. These results indicate that after the X-ray flux minimum, the hard component recovered its high state luminosity more rapidly than the high ionization spectral lines, but in the meantime it was partly occulted by a large amount of absorbing matter placed in front of the source. These results are discussed in the framework of the proposed binary model of eta Car. Based on space observations collected with the BeppoSAX X-Ray Astronomy Satellite which is a program of the Agenzia Spaziale Italiana with participation of the Netherlands Agency for Aerospace Programs, and on spectroscopic observations obtained at the Laboratrio Nacional de Astrofsica (LNA/MCT), Brazil, and at the Complejo Astronomico El Leoncito (CASLEO), Argentina.

  12. HARD X-RAY AND MICROWAVE EMISSIONS FROM SOLAR FLARES WITH HARD SPECTRAL INDICES

    SciTech Connect

    Kawate, T.; Nishizuka, N.; Oi, A.; Ohyama, M.; Nakajima, H.

    2012-03-10

    We analyze 10 flare events that radiate intense hard X-ray (HXR) emission with significant photons over 300 keV to verify that the electrons that have a common origin of acceleration mechanism and energy power-law distribution with solar flares emit HXRs and microwaves. Most of these events have the following characteristics. HXRs emanate from the footpoints of flare loops, while microwaves emanate from the tops of flare loops. The time profiles of the microwave emission show delays of peak with respect to those of the corresponding HXR emission. The spectral indices of microwave emissions show gradual hardening in all events, while the spectral indices of the corresponding HXR emissions are roughly constant in most of the events, though rather rapid hardening is simultaneously observed in some for both indices during the onset time and the peak time. These characteristics suggest that the microwave emission emanates from the trapped electrons. Then, taking into account the role of the trapping of electrons for the microwave emission, we compare the observed microwave spectra with the model spectra calculated by a gyrosynchrotron code. As a result, we successfully reproduce the eight microwave spectra. From this result, we conclude that the electrons that have a common acceleration and a common energy distribution with solar flares emit both HXR and microwave emissions in the eight events, though microwave emission is contributed to by electrons with much higher energy than HXR emission.

  13. An efficient plane-grating monochromator based on conical diffraction for continuous tuning in the entire soft X-ray range including tender X-rays (2-8 keV).

    PubMed

    Jark, Werner

    2016-01-01

    Recently it was verified that the diffraction efficiency of reflection gratings with rectangular profile, when illuminated at grazing angles of incidence with the beam trajectory along the grooves and not perpendicular to them, remains very high for tender X-rays of several keV photon energy. This very efficient operation of a reflection grating in the extreme off-plane orientation, i.e. in conical diffraction, offers the possibility of designing a conical diffraction monochromator scheme that provides efficient continuous photon energy tuning over rather large tuning ranges. For example, the tuning could cover photon energies from below 1000 eV up to 8 keV. The expected transmission of the entire instrument is high as all components are always operated below the critical angle for total reflection. In the simplest version of the instrument a plane grating is preceded by a plane mirror rotating simultaneously with it. The photon energy selection will then be made using the combination of a focusing mirror and exit slit. As is common for grating monochromators for soft X-ray radiation, the minimum spectral bandwidth is source-size-limited, while the bandwidth can be adjusted freely to any larger value. As far as tender X-rays (2-8 keV) are concerned, the minimum bandwidth is at least one and up to two orders of magnitude larger than the bandwidth provided by Si(111) double-crystal monochromators in a collimated beam. Therefore the instrument will provide more flux, which can even be increased at the expense of a bandwidth increase. On the other hand, for softer X-rays with photon energies below 1 keV, competitive relative spectral resolving powers of the order of 10000 are possible. PMID:26698063

  14. Removing Spectral Diagnostics of Galactic and Stellar X-Ray Emission from Charged Exchange Recombination

    NASA Technical Reports Server (NTRS)

    Wargelin, Brad

    2004-01-01

    Our research uses the electron beam ion trap (EBIT) at the Lawrence Livermore National Laboratory to study X-ray emission from the charge exchange (CX) of highly charged ions with neutral gases. The resulting data help to fill a void in existing experimental and theoretical understanding of this atomic physics process, and are needed to explain all or part of the observed X-ray emission from the soft X-ray background, stellar winds, the Galactic Center and Galactic Ridge, supernova ejecta, and photoionized nebulae. Appreciation of the astrophysical relevance of our work continues to grow with the publication of roughly a dozen papers in the past four years describing Chandra and XMM observations of geocoronal and heliospheric CX emission, the temporal variation of such emission and correlation with X-ray emission enhancements observed by ROSAT, the theoretical spatial distribution of that emission, and CX emission around other stars. A similar number of papers were also published during that time describing CX emission from planets and comets. We expect that the launch of ASTRSE2, with its second-generation XRS microcalo- (with 6-eV resolution), will reveal even more clearly the contributions of CX to astrophysical emission. In our EBIT work we collected CX spectra from such ions as H-like and He-like Ne, Ar, and Fe. Our early measurements were made with a high-purity Ge detector, but during the second year we began operation of the first-generation XRS microcalorimeter (a twin of the XRS on ASTRO-E) and greatly improved the resolution of our measurements from roughly 150 eV (FWHM) with the Ge detectors to 10 eV with the XRS. We found that saturation of the XRS counting apparatus, which we described in our proposal as a potential concern, is not a problem for studying CX. During the course of our research, we expanded the number of injection gases permitted by the LLNL safety team, purchased and eventually operated an atomic H source, and clearly demonstrated the feasibility of our longer-range plan. For example, we successfully injected He into EBIT (not a small feat because of the difficulty of maintaining a good vacuum with He and avoiding electrical breakdown) to collect a H-like oxygen CX spectrum. The highest energy CX spectrum recorded with the XRS to date is that of the Ar K-shell emission. These measurements provided the first observation of the relative intensity ratios of resolved He-like singlet and triplet n=2->1 lines. We also carried out measurements of He-like Ne as a function of collision energy (i.e., ion temperature). Significant differences in the resulting x-ray spectra were noted. In all cases, the intensity of high-n H-like Lyman lines is significantly higher than current theoretical CX models predict.

  15. Spectral variability in the X-ray pulsar GX 1+4

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

    Observations of the galactic center region, hard X-ray source GX 1+4 by the GSFC X-ray spectroscopy experiment on OSO-8 confirm that GX 1+4 is a slow X-ray pulsar. The amount of absorption by cold matter in the spectrum of GX 1+4 varies significantly within a 24 hour period, behavior typical of many X-ray binary systems. The light curve for the pulsations from GX 1+4 appears to be energy dependent.

  16. Image-based spectral distortion correction for photon-counting x-ray detectors

    PubMed Central

    Ding, Huanjun; Molloi, Sabee

    2012-01-01

    Purpose: To investigate the feasibility of using an image-based method to correct for distortions induced by various artifacts in the x-ray spectrum recorded with photon-counting detectors for their application in breast computed tomography (CT). Methods: The polyenergetic incident spectrum was simulated with the tungsten anode spectral model using the interpolating polynomials (TASMIP) code and carefully calibrated to match the x-ray tube in this study. Experiments were performed on a Cadmium-Zinc-Telluride (CZT) photon-counting detector with five energy thresholds. Energy bins were adjusted to evenly distribute the recorded counts above the noise floor. BR12 phantoms of various thicknesses were used for calibration. A nonlinear function was selected to fit the count correlation between the simulated and the measured spectra in the calibration process. To evaluate the proposed spectral distortion correction method, an empirical fitting derived from the calibration process was applied on the raw images recorded for polymethyl methacrylate (PMMA) phantoms of 8.7, 48.8, and 100.0 mm. Both the corrected counts and the effective attenuation coefficient were compared to the simulated values for each of the five energy bins. The feasibility of applying the proposed method to quantitative material decomposition was tested using a dual-energy imaging technique with a three-material phantom that consisted of water, lipid, and protein. The performance of the spectral distortion correction method was quantified using the relative root-mean-square (RMS) error with respect to the expected values from simulations or areal analysis of the decomposition phantom. Results: The implementation of the proposed method reduced the relative RMS error of the output counts in the five energy bins with respect to the simulated incident counts from 23.0%, 33.0%, and 54.0% to 1.2%, 1.8%, and 7.7% for 8.7, 48.8, and 100.0 mm PMMA phantoms, respectively. The accuracy of the effective attenuation coefficient of PMMA estimate was also improved with the proposed spectral distortion correction. Finally, the relative RMS error of water, lipid, and protein decompositions in dual-energy imaging was significantly reduced from 53.4% to 6.8% after correction was applied. Conclusions: The study demonstrated that dramatic distortions in the recorded raw image yielded from a photon-counting detector could be expected, which presents great challenges for applying the quantitative material decomposition method in spectral CT. The proposed semi-empirical correction method can effectively reduce these errors caused by various artifacts, including pulse pileup and charge sharing effects. Furthermore, rather than detector-specific simulation packages, the method requires a relatively simple calibration process and knowledge about the incident spectrum. Therefore, it may be used as a generalized procedure for the spectral distortion correction of different photon-counting detectors in clinical breast CT systems. PMID:22482608

  17. Status and perspectives of high-resolution spectroscopy in the soft x-ray range (invited)

    SciTech Connect

    Kaindl, G.; Domke, M.; Laubschat, C.; Weschke, E.; Xue, C. )

    1992-01-01

    The present status in high-resolution photoabsorption and photoemission spectroscopy using synchrotron radiation in the soft x-ray range (40 eV{le}{ital h}{nu}{le}1000 eV) is described. With the SX700/II monochromator, operated by the Freie Universitaet Berlin at the Berliner Elektronenspeicherring fuer Synchrotronstrahlung (BESSY), a resolving power of up to {ge}10 000 has been achieved. A practical feature of this monochromator is given by the fact that excellent energy resolution is achieved with a single 1221-lines/mm grating in the whole soft x-ray range considered. This opens up new opportunities in core-level photoabsorption spectroscopy of atoms, molecules, adsorbed species, and solids. A combination of the SX700/II beam line with a high-resolution electron spectrometer ({Delta}{ital E}{congruent}15 meV) enables resonant photoemission studies of rare-earth materials in the 4{ital d}{r arrow}4{ital f} giant-resonance region with unprecedented resolution and also at the 3{ital d}{r arrow}4{ital f} absorption thresholds. This spectroscopic progress provides new insight into the correlated electronic structure of Ce systems.

  18. Recovery of x-ray absorption spectral profile in etched TiO{sub 2} thin films

    SciTech Connect

    Sano, Keiji; Niibe, Masahito; Kawakami, Retsuo; Nakano, Yoshitaka

    2015-05-15

    Near edge x-ray absorption fine structure (NEXAFS) spectra of plasma-etched TiO{sub 2} thin films were observed using the total fluorescence yield method involving visible emission. The disrupted spectrum recovered its as-grown (nonetched) profile, upon soft x-ray (SX) irradiation. This recovery was investigated by ultraviolet (UV) irradiation, spatial distribution measurements, exposing recovered samples to air, and NEXAFS measurements of ultrafine TiO{sub 2} particles. The spectral profile recovered upon UV irradiation, and at sample positions outside of the SX irradiation site. The recovered spectral profiles were disrupted again, upon exposure to air. Nonetched ultrafine TiO{sub 2} particles also exhibited a disrupted spectral profile, which was recovered upon SX irradiation. The spectral recovery is explained by a model involving electrons trapped in oxygen vacancies generated by etching.

  19. Absolute x-ray energy calibration over a wide energy range using a diffraction-based iterative method

    SciTech Connect

    Hong Xinguo; Chen Zhiqiang; Duffy, Thomas S.

    2012-06-15

    In this paper, we report a method of precise and fast absolute x-ray energy calibration over a wide energy range using an iterative x-ray diffraction based method. Although accurate x-ray energy calibration is indispensable for x-ray energy-sensitive scattering and diffraction experiments, there is still a lack of effective methods to precisely calibrate energy over a wide range, especially when normal transmission monitoring is not an option and complicated micro-focusing optics are fixed in place. It is found that by using an iterative algorithm the x-ray energy is only tied to the relative offset of sample-to-detector distance, which can be readily varied with high precision of the order of 10{sup -5}-10{sup -6} spatial resolution using gauge blocks. Even starting with arbitrary initial values of 0.1 A, 0.3 A, and 0.4 A, the iteration process converges to a value within 3.5 eV for 31.122 keV x-rays after three iterations. Different common diffraction standards CeO{sub 2}, Au, and Si show an energy deviation of 14 eV. As an application, the proposed method has been applied to determine the energy-sensitive first sharp diffraction peak of network forming GeO{sub 2} glass at high pressure, exhibiting a distinct behavior in the pressure range of 2-4 GPa. Another application presented is pair distribution function measurement using calibrated high-energy x-rays at 82.273 keV. Unlike the traditional x-ray absorption-based calibration method, the proposed approach does not rely on any edges of specific elements, and is applicable to the hard x-ray region where no appropriate absorption edge is available.

  20. Time-Resolved Measurements of Polarized X-Ray Spectral Lines Emitted from Discharges of the Plasma-Focus Type

    SciTech Connect

    Jakubowski, L.; Sadowski, M. J.; Stanislawski, J.; Baronova, E. O.

    2006-01-15

    The paper presents results of experimental studies of the polarization of the X-ray spectral lines observed during high-current Plasma-Focus (PF) discharges. Time-resolved measurements of the highly-ionized argon lines were performed within the MAJA-PF facility operated at 44 kJ. The detailed studies confirmed considerable differences in relative intensities of the investigated spectral lines, what could be treated as an evidence of their different polarization.

  1. Discovery of Spatial and Spectral Structure in the X-Ray Emission from the Crab Nebula

    NASA Technical Reports Server (NTRS)

    Weisskopf, M.; Hester, J. J.; Tennant, A. F.; Elsner, R. F.; Schulz, N. S.; Marshall, H. L.; Karovska, M.; Nichols, J. S.; Swartz, D. A.; Kolodziejczak, J. J.

    2000-01-01

    The Chandra X-ray Observatory observed the Crab Nebula and Pulsar During orbital calibration. Zeroth-order images with the High-Energy Transmission Grating (HETG) read-out by the Advanced CCD Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of X-ray structure, at a resolution comparable to that of the best ground-based visible-light observations. The HETG-ACIS-S images reveal, for the first time, an X-ray knots along the inner ring and (perhaps) along the inward extension of the X-ray jet. Although complicated by instrumental effects and the brightness of the Crab Nebula, the spectrometric analysis shows systematic variations of the X-ray spectrum throughout the Nebula.

  2. Can We Reproduce the X-Ray Background Spectral Shape Using Local Active Galactic Nuclei?

    NASA Astrophysics Data System (ADS)

    Vasudevan, Ranjan V.; Mushotzky, Richard F.; Gandhi, Poshak

    2013-06-01

    The X-ray background (XRB) is due to the aggregate of active galactic nuclei (AGNs), which peak in activity at z ~ 1 and is often modeled as the sum of different proportions of unabsorbed, moderately, and heavily absorbed AGN. We present the summed spectrum of a complete sample of local AGN (the Northern Galactic Cap of the 58 month Swift/BAT catalog, z < 0.2) using 0.4-200 keV data and directly determine the different proportions of unabsorbed, moderately and heavily absorbed AGN that make up the summed spectrum. This stacked low redshift AGN spectrum is remarkably similar in shape to the XRB spectrum (when shifted to z ~ 1), but the observed proportions of different absorption populations differ from most XRB synthesis models. AGN with Compton-thick absorption account for only ~12% of the sample, but produce a significant contribution to the overall spectrum. We confirm that Compton reflection is more prominent in moderately absorbed AGN and that the photon index differs intrinsically between unabsorbed and absorbed AGN. The AGN in our sample account for only ~1% of the XRB intensity. The reproduction of the XRB spectral shape suggests that strong evolution in individual AGN properties is not required between z ~ 0 and 1.

  3. Monte Carlo validation of optimal material discrimination using spectral x-ray imaging

    NASA Astrophysics Data System (ADS)

    Nik, S. J.; Thing, R. S.; Watts, R.; Dale, T.; Currie, B.; Meyer, J.

    2014-08-01

    The aim of this work was to develop a framework to validate an algorithm for determination of optimal material discrimination in spectral x-ray imaging. Using Monte Carlo (MC) simulations based on the BEAMnrc package, material decomposition was performed on the projection images of phantoms containing up to three materials. The simulated projection data was first decomposed into material basis images by minimizing the z-score between expected and simulated counts. Statistical analysis was performed for the pixels within the region-of-interest consisting of contrast material(s) in the MC simulations. With the consideration of scattered radiation and a realistic scanning geometry, the theoretical optima of energy bin borders provided by the algorithm were shown to have an accuracy of ±2 keV for the decomposition of 2 and 3 materials. Finally, the signal-to-noise ratio predicted by the theoretical model was also validated. The counts per pixel needed for achieving a specific imaging aim can therefore be estimated using the validated model.

  4. FULL SPECTRAL SURVEY OF ACTIVE GALACTIC NUCLEI IN THE ROSSI X-RAY TIMING EXPLORER ARCHIVE

    SciTech Connect

    Rivers, Elizabeth; Markowitz, Alex; Rothschild, Richard

    2013-08-01

    We have analyzed spectra for all active galactic nuclei (AGNs) in the Rossi X-ray Timing Explorer archive. We present long-term average values of absorption, Fe line equivalent width (EW), Compton reflection, and photon index, and calculate fluxes and luminosities in the 2-10 keV band for 100 AGN with sufficient brightness and overall observation time to yield high-quality spectral results. We compare these parameters across the different classifications of Seyferts and blazars. Our distributions of photon indices for Seyfert 1s and 2s are consistent with the idea that Seyferts share a common central engine; however, our distributions of Compton reflection hump strengths do not support the classical picture of absorption by a torus and reflection off a Compton-thick disk with type depending only on inclination angle. We conclude that a more complex reflecting geometry such as a combined disk and torus or clumpy torus is likely a more accurate picture of the Compton-thick material. We find that Compton reflection is present in {approx}85% of Seyferts and by comparing Fe line EW's to Compton reflection hump strengths we have found that on average 40% of the Fe line arises in Compton thick material; however, this ratio was not consistent from object to object and did not seem to be dependent on optical classification.

  5. Temperature-dependent spectral weight transfer in YBa2Cu3Ox probed by x-ray absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Lin, J.-Y.

    2010-03-01

    The x-ray absorption spectroscopy was utilized to critically examine the temperature dependency of the spectral weight in YBa2Cu3Ox. Large excess spectral weight for the Zhang- Rice singlet due to dynamics of holes is found with its doping dependence showing similar doom-like shape as that for Tc. Furthermore, appreciable spectral weight transfer from the upper Hubbard band to Zhang-Rice singlet was observed as the temperature acrosses the onset temperature for the pseudogap. The observed spectral weight transfer follows the change of the pseudogap, indicating a strong link between pseudogap and the upper Hubbard band.

  6. Analysis of X-ray spectral variability and black hole mass determination of the NLS1 galaxy Mrk 766

    NASA Astrophysics Data System (ADS)

    Giacchè, S.; Gilli, R.; Titarchuk, L.

    2014-02-01

    We present an XMM-Newton time-resolved spectral analysis of the narrow-line Seyfert 1 galaxy Mrk 766. We analysed eight available observations taken between May 2000 and June 2005 with the EPIC-pn camera in order to investigate the X-ray spectral variability produced by changes in the mass accretion rate. The 0.2 - 10 keV spectra are extracted in time bins longer than 3 ks to have at least 3 × 104 net counts in each bin and then accurately trace the variations of the best-fit parameters of our adopted Comptonization spectral model. We tested a bulk-motion Comptonization (BMC) model which is in general applicable to any physical system powered by accretion onto a compact object, and assumes that soft seed photons are efficiently up-scattered via inverse Compton scattering in a hot and dense electron corona. The Comptonized spectrum has a characteristic power law shape, whose slope was found to increase for large values of the normalization of the seed component, which is proportional to the mass accretion rate ṁ (in Eddington units). Our baseline spectral model also includes a warm absorber lying on the line of sight and radiation reprocessing from the accretion disc or from outflowing matter in proximity to the central compact object. Our study reveals that the normalization-slope correlation, observed in Galactic black hole sources (GBHs), also holds for Mrk 766: variations of the photon index in the range Γ ~ 1.9-2.4 are indeed likely to be related to the variations of ṁ, as observed in X-ray binary systems. We finally applied a scaling technique based on the observed correlation to estimate the BH mass in Mrk 766. This technique is commonly and successfully applied to measure masses of GBHs, and this is the first time it has been applied in detail to estimate the BH mass in an AGN. We obtained a value of MBH = 1.26-0.77+1.00×106 M⊙, which is in very good agreement with that estimated by the reverberation mapping. Appendix A is available in electronic form at http://www.aanda.org

  7. Note: Effect of photodiode aluminum cathode frame on spectral sensitivity in the soft x-ray energy band

    SciTech Connect

    McGarry, M. B. Den Hartog, D. J.; Goetz, J. A.; Johnson, J.; Franz, P.

    2014-09-15

    Silicon photodiodes used for soft x-ray detection typically have a thin metal electrode partially covering the active area of the photodiode, which subtly alters the spectral sensitivity of the photodiode. As a specific example, AXUV4BST photodiodes from International Radiation Detectors have a 1.0 μm thick aluminum frame covering 19% of the active area of the photodiode, which attenuates the measured x-ray signal below ∼6 keV. This effect has a small systematic impact on the electron temperature calculated from measurements of soft x-ray bremsstrahlung emission from a high-temperature plasma. Although the systematic error introduced by the aluminum frame is only a few percent in typical experimental conditions on the Madison Symmetric Torus, it may be more significant for other instruments that use similar detectors.

  8. A fully Bayesian method for jointly fitting instrumental calibration and X-ray spectral models

    SciTech Connect

    Xu, Jin; Yu, Yaming; Van Dyk, David A.; Kashyap, Vinay L.; Siemiginowska, Aneta; Drake, Jeremy; Ratzlaff, Pete; Connors, Alanna; Meng, Xiao-Li E-mail: yamingy@ics.uci.edu E-mail: vkashyap@cfa.harvard.edu E-mail: jdrake@cfa.harvard.edu E-mail: meng@stat.harvard.edu

    2014-10-20

    Owing to a lack of robust principled methods, systematic instrumental uncertainties have generally been ignored in astrophysical data analysis despite wide recognition of the importance of including them. Ignoring calibration uncertainty can cause bias in the estimation of source model parameters and can lead to underestimation of the variance of these estimates. We previously introduced a pragmatic Bayesian method to address this problem. The method is 'pragmatic' in that it introduced an ad hoc technique that simplified computation by neglecting the potential information in the data for narrowing the uncertainty for the calibration product. Following that work, we use a principal component analysis to efficiently represent the uncertainty of the effective area of an X-ray (or γ-ray) telescope. Here, however, we leverage this representation to enable a principled, fully Bayesian method that coherently accounts for the calibration uncertainty in high-energy spectral analysis. In this setting, the method is compared with standard analysis techniques and the pragmatic Bayesian method. The advantage of the fully Bayesian method is that it allows the data to provide information not only for estimation of the source parameters but also for the calibration product—here the effective area, conditional on the adopted spectral model. In this way, it can yield more accurate and efficient estimates of the source parameters along with valid estimates of their uncertainty. Provided that the source spectrum can be accurately described by a parameterized model, this method allows rigorous inference about the effective area by quantifying which possible curves are most consistent with the data.

  9. Flat panel X-ray detector with reduced internal scattering for improved attenuation accuracy and dynamic range

    DOEpatents

    Smith, Peter D. (Santa Fe, NM); Claytor, Thomas N. (White Rock, NM); Berry, Phillip C. (Albuquerque, NM); Hills, Charles R. (Los Alamos, NM)

    2010-10-12

    An x-ray detector is disclosed that has had all unnecessary material removed from the x-ray beam path, and all of the remaining material in the beam path made as light and as low in atomic number as possible. The resulting detector is essentially transparent to x-rays and, thus, has greatly reduced internal scatter. The result of this is that x-ray attenuation data measured for the object under examination are much more accurate and have an increased dynamic range. The benefits of this improvement are that beam hardening corrections can be made accurately, that computed tomography reconstructions can be used for quantitative determination of material properties including density and atomic number, and that lower exposures may be possible as a result of the increased dynamic range.

  10. OSO-7 observations of solar X-rays in the energy range 10-100 keV

    NASA Technical Reports Server (NTRS)

    Datlowe, D. W.; Elcan, M. J.; Hudson, H. S.

    1974-01-01

    Data on 123 hard X-ray bursts observed by the satellite OSO-7 between Oct. 10, 1971 and June 6, 1972 are described and evaluated. Typical duration of a burst is 100 sec. Average spectral indices lie between 3.5 and 5.5 for two-thirds of the 123 bursts, with a median of 4.6. In some events a soft-hard-soft pattern is observed, but there are numerous examples in which the spectrum softens continuously throughout the burst. The mean shape of the hard X-ray time profile as measured by the full width at half maximum does not depend on burst amplitude; nor does the spectral hardness correlate with the flux. The distribution of burst peak fluxes and the observation of large soft X-ray bursts without accompanying hard X rays suggest the existence of a distinct class of solar flares which emit only soft X rays. No center-to-limb variation was found in the frequency of occurrence of bursts or in the fraction with a nonthermal component. Estimates of the energy in the form of nonthermal electrons and in the flare plasma derived from these data indicate that the total amounts in each are comparable.

  11. X-ray spectral line coincidences between fluorine K- and transition-metal L-series lines

    SciTech Connect

    Burkhalter, P.G.; Charatis, G.; Rockett, P.D.

    1983-11-01

    X-ray spectroscopy was performed in the 12--15-A region, recording L-series lines from selected laser-irradiated transition metals. Line coincidences and near coincidences were identified between Cr, Mn, Fe, and Ni L spectra, and F VIII and F IX K-shell lines. Wavelengths were determined to accuracies of 1--3 mA and will be utilized in selecting potential pumping candidates in future x-ray lasing schemes. High-resolution x-ray spectra were collected under controlled illumination and target conditions, using 1.05- and 0.527-..mu..m laser excitation with the KMS CHROMA laser. Laser intensity varied from 1.2--2.5 x 10/sup 14/ W/cm/sup 2/ in 200-ps pulses. Three groups of x-ray spectra were collected with highly dispersive x-ray crystals at wave bands centered at 12.643, 13.781, and 14.458 A, corresponding to H- and He-like lines from fluorine. Two specially designed flat crystal spectrographs employing camera shutters were used with pairs of beryl and thallium acid phthalate (TAP) crystals. The spectra from potential lasant and pump candidates could be recorded on the same spectrogram to aid in identifying x-ray line coincidences. In cases where wavelengths were measured in both the 1.05- and 0.527-..mu..m laser work, agreement within 1--3 mA was obtained for the L-series x-ray lines. Within this accuracy range, some five L-series x-ray lines, mostly 2p-3d transitions from the metals Cr, Mn, and Ni, had wavelength values coincident with K-series lines in fluorine.

  12. Spectral and Timing Investigations of Dwarf Novae Selected in Hard X-Rays

    NASA Technical Reports Server (NTRS)

    Thorstensen, John; Remillard, Ronald A.

    2000-01-01

    There are 9 dwarf novae (DN) among the 43 cataclysmic variables (accreting white dwarfs in close binary systems) that were detected during the HEAO-1 all-sky X-ray survey (1977-1979). On the other hand, there are roughly one hundred dwarf novae that are closer and/or optically brighter and yet they were not detected as hard X-ray sources. Two of the HEAO-1 DN show evidence for X-ray pulsations that imply strong magnetic fields on the white dwarf surface, and magnetic CVs are known to be strong X-ray sources. However, substantial flux in hard X-rays may be caused by non-magnetic effects, such as an optically thin boundary layer near a massive white dwarf. We proposed RXTE observations to measure plasma temperatures and to search for X-ray pulsations. The observations would distinguish whether these DN belong to one of (rare) magnetic subclasses. For those that do not show pulsations, the observations support efforts to define empirical relations between X-ray temperature, the accretion rate, and the mass of the white dwarf. The latter is determined via optical studies of the dynamics of the binary constituents.

  13. High-resolution single-shot spectral monitoring of hard x-ray free-electron laser radiation

    SciTech Connect

    Makita, M.; Karvinen, P.; Zhu, D.; Juranic, P. N.; Grünert, J.; Cartier, S.; Jungmann-Smith, J. H.; Lemke, H. T.; Mozzanica, A.; Nelson, S.; Patthey, L.; Sikorski, M.; Song, S.; Feng, Y.; David, C.

    2015-10-16

    We have developed an on-line spectrometer for hard x-ray free-electron laser (XFEL) radiation based on a nanostructured diamond diffraction grating and a bent crystal analyzer. Our method provides high spectral resolution, interferes negligibly with the XFEL beam, and can withstand the intense hard x-ray pulses at high repetition rates of >100 Hz. The spectrometer is capable of providing shot-to-shot spectral information for the normalization of data obtained in scientific experiments and optimization of the accelerator operation parameters. We have demonstrated these capabilities of the setup at the Linac Coherent Light Source, in self-amplified spontaneous emission mode at full energy of >1 mJ with a 120 Hz repetition rate, obtaining a resolving power of Ε/δΕ > 3 × 104. In conclusion, the device was also used to monitor the effects of pulse duration down to 8 fs by analysis of the spectral spike width.

  14. Spectral Diagnostics of Galactic and Stellar X-Ray Emission from Charge Exchange Recombination

    NASA Technical Reports Server (NTRS)

    Wargelin, B.

    2002-01-01

    The proposed research uses the electron beam ion trap at the Lawrence Livermore National Laboratory (LLNL) to study X-ray emission from charge-exchange recombination of highly charged ions with neutral gases. The resulting data fill a void in existing experimental and theoretical understanding of this atomic physics process, and are needed to explain all or part of the observed X-ray emission from the soft X-ray background, stellar winds, the Galactic Center, supernova ejecta, and photoionized nebulae. Progress made during the first year of the grant is described, as is work planned for the second year.

  15. On the Nature of the mHz X-ray Quasi-Periodic Oscillations from Ultraluminous X-ray source M82 X-1: Search for Timing-Spectral Correlations

    NASA Technical Reports Server (NTRS)

    Pasham, Dheeraj R.; Strohmayer, Tod E.

    2013-01-01

    Using all the archival XMM-Newton X-ray (3-10 keV) observations of the ultraluminous X-ray source (ULX) M82 X-1, we searched for a correlation between its variable mHz quasi-periodic oscillation (QPO) frequency and its hardness ratio (5-10 keV/3-5 keV), an indicator of the energy spectral power-law index. When stellar-mass black holes (StMBHs) exhibit type-C low-frequency QPOs (0.2-15 Hz), the centroid frequency of the QPO is known to correlate with the energy spectral index. The detection of such a correlation would strengthen the identification of M82 X-1's mHz QPOs as type-C and enable a more reliable mass estimate by scaling its QPO frequencies to those of type-C QPOs in StMBHs of known mass.We resolved the count rates and the hardness ratios of M82 X-1 and a nearby bright ULX (source 5/X42.3+59) through surface brightness modeling.We detected QPOs in the frequency range of 36-210 mHz during which M82 X-1's hardness ratio varied from 0.42 to 0.47. Our primary results are (1) that we do not detect any correlation between the mHz QPO frequency and the hardness ratio (a substitute for the energy spectral power-law index) and (2) similar to some accreting X-ray binaries, we find that M82 X-1's mHz QPO frequency increases with its X-ray count rate (Pearson's correlation coefficient = +0.97). The apparent lack of a correlation between the QPO centroid frequency and the hardness ratio poses a challenge to the earlier claims that the mHz QPOs of M82 X-1 are the analogs of the type-C low-frequency QPOs of StMBHs. On the other hand, it is possible that the observed relation between the hardness ratio and the QPO frequency represents the saturated portion of the correlation seen in type-C QPOs of StMBHs-in which case M82 X-1's mHz QPOs can still be analogous to type-C QPOs.

  16. ON THE NATURE OF THE mHz X-RAY QUASI-PERIODIC OSCILLATIONS FROM ULTRALUMINOUS X-RAY SOURCE M82 X-1: SEARCH FOR TIMING-SPECTRAL CORRELATIONS

    SciTech Connect

    Pasham, Dheeraj R.; Strohmayer, Tod E. E-mail: tod.strohmayer@nasa.gov

    2013-07-10

    Using all the archival XMM-Newton X-ray (3-10 keV) observations of the ultraluminous X-ray source (ULX) M82 X-1, we searched for a correlation between its variable mHz quasi-periodic oscillation (QPO) frequency and its hardness ratio (5-10 keV/3-5 keV), an indicator of the energy spectral power-law index. When stellar-mass black holes (StMBHs) exhibit type-C low-frequency QPOs ({approx}0.2-15 Hz), the centroid frequency of the QPO is known to correlate with the energy spectral index. The detection of such a correlation would strengthen the identification of M82 X-1's mHz QPOs as type-C and enable a more reliable mass estimate by scaling its QPO frequencies to those of type-C QPOs in StMBHs of known mass. We resolved the count rates and the hardness ratios of M82 X-1 and a nearby bright ULX (source 5/X42.3+59) through surface brightness modeling. We detected QPOs in the frequency range of 36-210 mHz during which M82 X-1's hardness ratio varied from 0.42 to 0.47. Our primary results are (1) that we do not detect any correlation between the mHz QPO frequency and the hardness ratio (a substitute for the energy spectral power-law index) and (2) similar to some accreting X-ray binaries, we find that M82 X-1's mHz QPO frequency increases with its X-ray count rate (Pearson's correlation coefficient = +0.97). The apparent lack of a correlation between the QPO centroid frequency and the hardness ratio poses a challenge to the earlier claims that the mHz QPOs of M82 X-1 are the analogs of the type-C low-frequency QPOs of StMBHs. On the other hand, it is possible that the observed relation between the hardness ratio and the QPO frequency represents the saturated portion of the correlation seen in type-C QPOs of StMBHs-in which case M82 X-1's mHz QPOs can still be analogous to type-C QPOs.

  17. Sensitivity study of ignition capsule implosion performance on the hard x-ray spectral distribution of hohlraum

    SciTech Connect

    Gu Jianfa; Zou Shiyang; Li Yongsheng; Dai Zhensheng; Ye Wenhua

    2012-12-15

    The paper investigates theoretically the sensitivities of ignition capsule implosion performance on the hard x-ray spectral distribution of hohlraum. In the simulation, the hohlraum radiation is represented by a Planckian spectrum for the main drive plus a gaussian bump centered at energy E{sub c} for preheating x-rays. Simulation results show that with the increasing of center energy E{sub c}, the Atwood number at the fuel-ablator interface increases rapidly due to the preheating and expanding of the inner undoped CH layer. The growing of Atwood number indicates the hydrodynamic instability (HI) growth and mixing at this interface. On the other hand, the increasing of E{sub c} results in a large density gradient scale length of ablation front and stabilizes the HI growth at ablation front. The changes of the hard x-ray spectrum have significant influences on other important implosion parameters including the ablator mass remaining, shock timing, implosion velocity, and yield as well. High-precision results on the hard x-ray spectral distribution of hohlraum are thus critical for optimizing the ignition capsule design to limit the HI growth.

  18. Sensitivity study of ignition capsule implosion performance on the hard x-ray spectral distribution of hohlraum

    NASA Astrophysics Data System (ADS)

    Gu, Jianfa; Zou, Shiyang; Li, Yongsheng; Dai, Zhensheng; Ye, Wenhua

    2012-12-01

    The paper investigates theoretically the sensitivities of ignition capsule implosion performance on the hard x-ray spectral distribution of hohlraum. In the simulation, the hohlraum radiation is represented by a Planckian spectrum for the main drive plus a gaussian bump centered at energy Ec for preheating x-rays. Simulation results show that with the increasing of center energy Ec, the Atwood number at the fuel-ablator interface increases rapidly due to the preheating and expanding of the inner undoped CH layer. The growing of Atwood number indicates the hydrodynamic instability (HI) growth and mixing at this interface. On the other hand, the increasing of Ec results in a large density gradient scale length of ablation front and stabilizes the HI growth at ablation front. The changes of the hard x-ray spectrum have significant influences on other important implosion parameters including the ablator mass remaining, shock timing, implosion velocity, and yield as well. High-precision results on the hard x-ray spectral distribution of hohlraum are thus critical for optimizing the ignition capsule design to limit the HI growth.

  19. Spektr: a computational tool for x-ray spectral analysis and imaging system optimization.

    PubMed

    Siewerdsen, J H; Waese, A M; Moseley, D J; Richard, S; Jaffray, D A

    2004-11-01

    A set of computational tools are presented that allow convenient calculation of x-ray spectra, selection of elemental and compound filters, and calculation of beam quality characteristics, such as half-value layer, mR/mAs, and fluence per unit exposure. The TASMIP model of Boone and Seibert is adapted to a library of high-level language (Matlab) functions and shown to agree with experimental measurements across a wide range of kVp and beam filtration. Modeling of beam filtration is facilitated by a convenient, extensible database of mass and mass-energy attenuation coefficients compiled from the National Institute of Standards and Technology. The functions and database were integrated in a graphical user interface and made available online at http:// www.aip.org/epaps/epaps.html. The functionality of the toolset and potential for investigation of imaging system optimization was illustrated in theoretical calculations of imaging performance across a broad range of kVp, filter material type, and filter thickness for direct and indirect-detection flat-panel imagers. The calculations reveal a number of nontrivial effects in the energy response of such detectors that may not have been guessed from simple K-edge filter techniques, and point to a variety of compelling hypotheses regarding choice of beam filtration that warrant future investigation. PMID:15587659

  20. Short term X-ray spectral variability of the quasar PDS 456 observed in a low flux state

    NASA Astrophysics Data System (ADS)

    Matzeu, G. A.; Reeves, J. N.; Nardini, E.; Braito, V.; Costa, M. T.; Tombesi, F.; Gofford, J.

    2016-02-01

    We present a detailed analysis of a recent, 2013 Suzaku campaign on the nearby (z = 0.184) luminous (Lbol ˜ 1047 erg s-1) quasar PDS 456. This consisted of three observations, covering a total duration of ˜1 Ms and a net exposure of 455 ks. During these observations, the X-ray flux was unusually low, suppressed by a factor of >10 in the soft X-ray band when compared to previous observations. We investigated the broadband continuum by constructing a Spectral Energy Distribution (SED), making use of the optical/UV photometry and hard X-ray spectra from the later simultaneous XMM-Newton and NuSTAR campaign in 2014. The high energy part of this low flux SED cannot be accounted for by physically self consistent accretion disc and corona models without attenuation by absorbing gas, which partially covers a substantial fraction of the line of sight towards the X-ray continuum. At least two layers of absorbing gas are required, of column density log (NH, low/cm-2) = 22.3 ± 0.1 and log (NH, high/cm-2) = 23.2 ± 0.1, with average line of sight covering factors of ˜80% (with typical ˜5% variations) and 60% (±10 - 15%), respectively. During these observations PDS 456 displays significant short term X-ray spectral variability, on timescales of ˜100 ks, which can be accounted for by variable covering of the absorbing gas along the line of sight. The partial covering absorber prefers an outflow velocity of vpc = 0.25^{+0.01}_{-0.05}c at the >99.9% confidence level over the case where vpc = 0. This is consistent with the velocity of the highly ionised outflow responsible for the blueshifted iron K absorption profile. We therefore suggest that the partial covering clouds could be the denser, or clumpy part of an inhomogeneous accretion disc wind. Finally estimates are placed upon the size-scale of the X-ray emission region from the source variability. The radial extent of the X-ray emitter is found to be of the order ˜15 - 20 Rg, although the hard X-ray (>2 keV) emission may originate from a more compact or patchy corona of hot electrons, which is typically ˜6 - 8 Rg in size.

  1. Spectral Diagnostics of Galactic and Stellar X-Ray Emission from Charge Exchange Recombination

    NASA Technical Reports Server (NTRS)

    Wargelin, B.

    2003-01-01

    The proposed research uses the electron beam ion trap at the Lawrence Livermore National Laboratory to study the X-ray emission from charge-exchange recombination of highly charged ions with neutral gases. The resulting data fill a void in the existing experimental and theoretical data and are needed to explain all or part of the observed X-ray emission from the Galactic Ridge, solar and stellar winds, the Galactic Center, supernova ejecta, and photoionized nebulae.

  2. X-ray laser resonator for the kilo-electron-volt range

    SciTech Connect

    Chen, Jie; Key Laboratory for Laser Plasmas and Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 ; Tomov, Ivan V.; Er, Ali O.; Rentzepis, Peter M.

    2013-04-29

    We have designed, constructed, and tested an x-ray laser resonator operating in the hard x-ray, keV energy region. This ring x-ray laser cavity is formed by four highly oriented pyrolytic graphite crystals. The crystals are set at the Bragg angles that allow for the complete 360 Degree-Sign round trip of the 2.37 A, 5.23 keV L{sub {alpha}} line of neodymium. In addition, we also present experimental data of a similar ring laser resonator that utilizes the Cr K{sub {alpha}}, 5.41 keV, x-ray line to propagate through the four mirrors of the cavity. The specific properties of these x-ray laser resonator mirrors, including reflection losses and cavity arrangement, are presented.

  3. Impurity Emission Behavior in the Soft X-Ray and Extreme Ultraviolet Range on EAST

    NASA Astrophysics Data System (ADS)

    SHEN, Yongcai; LYU, Bo; DU, Xuewei; LI, Yingying; FU, Jia; WANG, Fudi; PAN, Xiayun; CHEN, Jun; WANG, Qiuping; Yuejiang, SHI

    2015-03-01

    Spectroscopy in the soft X-ray and extreme ultraviolet (XEUV) region is very important in magnetic fusion research. Recently, two flat-field spectrometers that utilize a varied line spacing grating to image the spectra of 1-13 nm and 5-50 nm were installed on EAST for core impurity emission monitoring and impurity transport study. The instruments were proven to be capable of observing spectral lines from low-Z impurities (Li, C, O, N, Ar, etc.) and highly ionized medium- and high-Z impurities (Fe, Cr, Ni, Cu, Mo, etc.). For example, spectra in the wavelength intervals of 1-2 nm and 5-13 nm contained strong metal lines, especially molybdenum lines during H-mode phases. Argon and nitrogen lines were also observed, which were injected for diagnostic purposes. Impurity lines were identified and compared to measurements on other magnetic fusion research devices. Detailed measurements of radial emission profiles from various impurity line emissions were also presented. supported by National Natural Science Foundation of China (Nos. 11175208, 11275231 and 11305207), the National Magnetic Confinement Fusion Science Program of China (Nos. 2012GB101001 and 2013GB112004), Scientific Instrument Development Project of Chinese Academy of Sciences (No. YZ200922) and JSPS-NRF-NSFC A3 Foresight Program in the Field of Plasma Physics (No. 11261140328)

  4. Prediction and Measurement of X-Ray Spectral and Intensity Distributions from Low Energy Electron Impact Sources

    NASA Technical Reports Server (NTRS)

    Edwards, David L.

    1999-01-01

    In-vacuum electron beam welding is a technology that NASA considered as a joining technique for manufacture of space structures. The interaction of energetic electrons with metal produces x-rays. The radiation exposure to astronauts performing the in-vacuum electron beam welding must be characterized and minimized to insure safe operating conditions. This investigation characterized the x-ray environment due to operation of an in-vacuum electron beam welding tool. NASA, in a joint venture with the Russian Space Agency, was scheduled to perform a series of welding in space experiments on board the United States Space Shuttle. This series of experiments was named the International Space Welding Experiment (ISWE). The hardware associated with the ISWE was leased to NASA, by the Paton Welding Institute (PWI) in Ukraine, for ground based welding experiments in preparation for flight. Two tests were scheduled, using the ISWE electron beam welding tool, to characterize the radiation exposure to an astronaut during the operation of the ISWE. These radiation exposure tests consisted of Thermoluminescence Dosimeters (TLD's) shielded with material currently used by astronauts during Extra Vehicular Activities (EVA) and exposed to x-ray radiation generated by operation of an in-vacuum electron beam welding tool. This investigation was the first known application of TLD's to measure absorbed dose from x-rays of energy less than 10 KeV. The ISWE hardware was returned to Ukraine before the issue of adequate shielding for the astronauts was verified. Therefore, alternate experimental and analytical methods were developed to measure and predict the x-ray spectral and intensity distribution generated by electron impact with metal. These x-ray spectra were used to calculate the absorbed radiation dose to astronauts. These absorbed dose values were compared to TLD measurements obtained during actual operation of the in-vacuum electron beam welding tool. The calculated absorbed dose values were found to be in good agreement with the TLD values.

  5. Time-resolved imaging and spectral studies of an X-ray burst from the globular cluster Terzan

    NASA Technical Reports Server (NTRS)

    Grindlay, J. E.; Marshall, H. L.; Hertz, P.; Weisskopf, M. C.; Elsner, R. F.; Ghosh, P.; Darbro, W.; Sutherland, P. G.; Soltan, A.

    1980-01-01

    The first image of an X-ray burst was recorded with the HRI detector at the Einstein Observatory while observing the globular cluster Terzan 2. The burst was coincident with a persistent X-ray source located near the center of the cluster (thus confirming an earlier suggested identification) and reached a peak luminosity exceeding 5 x 10 to the 38th (d/10 kpc) squared. After a rapid rise to peak luminosity, a double-peaked spectral variation was observed over the next approximately 20 s with anticorrelated changes in the apparent emission region radius and temperature derived from blackbody (and modified blackbody) spectral fits. A shell or disk geometry, which undergoes adiabatic expansion and contraction, may be implied for the burst emission region. Alternatively, Comptonization is required. It is also shown that the peak burst luminosity must exceed the Eddington limit.

  6. Assessing charging effects on spectral quality for X-ray microanalysis in low voltage and variable pressure/environmental scanning electron microscopy.

    PubMed

    Newbury, Dale E

    2004-12-01

    Energy dispersive X-ray spectrometry of uncoated insulators performed at low beam energy (incident energy < or = 5 keV) and in the variable pressure scanning electron microscope and the environmental scanning electron microscope is subject to spectral artifacts. Charging decelerates the incident beam electrons and reduces the impact energy, lowering the available overvoltage to excite characteristic X-ray peaks. The Duane-Hunt limit of the X-ray bremsstrahlung continuum is commonly used as a diagnostic of charging. Dynamic charging effects can hide the true impact of charging on the X-ray spectrum. Careful examination of the behavior of the X-ray spectrum with time and other variables is needed to avoid spectral artifacts, particularly on relative X-ray intensities. PMID:19780314

  7. The dependence of the soft X ray spectral slope with radio property, luminosity, and redshift, for a large sample of AGN from the Einstein IPC data base

    NASA Technical Reports Server (NTRS)

    Brunner, H.; Worrall, D. M.; Wilkes, Belinda J.; Elvis, Martin

    1989-01-01

    The dependence of the soft X-ray spectral slope on radio, optical and X-ray properties, and on redshift are reported for a large sample of Active Galactic Nuclei (AGN). The sample includes 317 optically and radio-selected AGN from a preliminary version of the Einstein Imaging Proportional Counter (IPC) quasar and AGN data base. The main results are: the difference in X-ray slope between radio-loud and radio-quiet AGN were confirmed for an independent and much larger sample of sources; a difference in X-ray slope between flat and steep radio spectrum AGN is observed only in high luminosity sub-sample; in flat radio spectrum AGNs there is an indication for a dependence of the X-ray spectral index on X-ray luminosity redshift and alpha sub 0x.

  8. Saturation and Dynamic Range of Microchannel Plate-Based X-Ray Imagers

    SciTech Connect

    ,

    2012-05-04

    This paper describes recent advances in Monte Carlo simulations of microchannel plate (MCP)based x-ray detectors, a continuation of ongoing work in this area. A Monte Carlo simulation model has been developed over the past several years by National Security Technologies, LLC (NSTec). The model simulates the secondary electron emission process in an MCP pore and includes the effects of gain saturation. In this work we focus on MCP gain saturation and dynamic range. We have performed modeling and experimental characterizations of L/D = 46, 10-micron diameter, MCP-based detectors. The detectors are typically operated by applying a subnanosecond voltage pulse, which gates the detector on. Agreement between the simulations and experiment is very good for a variety of voltage pulse waveforms ranging in width from 150 to 300 ps. The results indicate that such an MCP begins to show nonlinear gain around 5 10^4 electrons per pore and hard saturation around 105 electrons per pore. The simulations show a difference in MCP sensitivity vs voltage for high flux of photons producing large numbers of photoelectrons on a subpicosecond timescale. Simulations and experiments both indicate an MCP dynamic range of 1 to 10,000, and the dynamic range depends on how the voltage is applied.

  9. A spectral study of the persistent X-ray flux from 4 U/MXB 1636-53

    NASA Astrophysics Data System (ADS)

    Vacca, W. D.; Sztajno, M.; Lewin, W. H. G.; Truemper, J.; van Paradijs, J.; Smith, A.

    1987-01-01

    The authors present a spectral analysis of the persistent X-ray flux from the X-ray burst source 4U/MXB 1636-53, which was continuously observed with EXOSAT for about 25 h in May 1984. They find that no standard one-component spectral model provides an acceptable representation of all the data. However, almost all "complex one-component" and "two-component" models do accurately fit the data. A blackbody plus a "multicolor" disk spectrum does not fit the data. In addition, it is found that some "two-component" spectral models can be fitted to the data with more than one set of different parameter values. Based on these results it is suggested that the various physical scenarios that have been proposed to interpret "two-component" spectra of low-mass X-ray binaries may be based on mathematical parameterizations which may not provide unique representations of the data. If this is the case, the reported "two-component" mathematical fits may not have any true physical significance.

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

    SciTech Connect

    Trichas, Markos; Green, Paul J.; Aldcroft, Tom; Kim, Dong-Woo; Mossman, Amy; Silverman, John D.; Barkhouse, Wayne; Cameron, Robert A.; Constantin, Anca; Ellison, Sara L.; Foltz, Craig; Haggard, Daryl; Jannuzi, Buell T.; Marshall, Herman L.; Perez, Laura M.; Romero-Colmenero, Encarni; Ruiz, Angel; Smith, Malcolm G.; 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 activity. We have tested the hypothesis that there should be a strong connection between X-ray obscuration and star formation but we do not find any association between X-ray column density and star formation rate both in the general population or the star-forming X-ray Seyferts. Our large compilation also allows us to report here the identification of 81 X-ray Bright Optically inactive Galaxies, 78 z > 3 X-ray sources, and eight Type-2 QSO candidates. Also, we have identified the highest redshift (z = 5.4135) X-ray-selected QSO with optical spectroscopy.

  11. Solar active region physical parameters inferred from a thermal cyclotron line and soft X-ray spectral lines

    NASA Technical Reports Server (NTRS)

    Lang, Kenneth R.; Willson, Robert F.; Smith, Kermit L.; Strong, Keith T.

    1987-01-01

    Simultaneous high-resolution observations of coronal loops were made at the 20-cm wavelength with the VLA and at soft X-ray wavelengths with the SMM FCS. The images obtained at both wavelengths have nearly identical sizes and ellipsoidal shapes, with the emission stretching between and across regions of opposite magnetic polarity in the underlying photosphere. The results indicate that the radiation at 20 cm and soft X-ray wavelengths originates from the same region, and that 20 cm maps can image X-ray coronal loops. The X-ray spectral lines were used to obtain values of electron temperature, T(e), of about 2.6 x 10 to the 6th K and electron density, N(e), of about 3.1 x 10 to the 9th/cu cm. These parameters were used to show that the layers emitting 20-cm radiation can be optically thick to either thermal bremsstrahlung or thermal gyroresonance radiation, depending upon unknown but plausible values of loop thickness, magnetic scale height, and magnetic field strength.

  12. Spectral analysis of paramagnetic centers induced in human tooth enamel by x-rays and gamma radiation

    NASA Astrophysics Data System (ADS)

    Kirillov, V. A.; Kuchuro, I. I.

    2010-03-01

    Based on study of spectral and relaxation characteristics, we have established that paramagnetic centers induced in tooth enamel by x-rays and gamma radiation are identical in nature. We show that for the same exposure dose, the intensity of the electron paramagnetic resonance (EPR) signal induced by x-radiation with effective energy 34 keV is about an order of magnitude higher than the amplitude of the signal induced by gamma radiation. We have identified a three-fold attenuation of the EPR signal along the path of the x-radiation from the buccal to the lingual side of a tooth, which is evidence that the individual had undergone diagnostic x-ray examination of the dentition or skull. We have shown that the x-ray exposure doses reconstructed from the EPR spectra are an order of magnitude higher than the applied doses, while the dose loads due to gamma radiation are equal to the applied doses. The data obtained indicate that for adequate reconstruction of individual absorbed doses from EPR spectra of tooth enamel in the population subjected to the combined effect of x-radiation and accidental external gamma radiation as a result of the disaster at the Chernobyl nuclear power plant, we need to take into account the contribution to the dose load from diagnostic x-rays in examination of the teeth, jaw, or skull.

  13. X-ray spectral line coincidences between fluorine VIII (and IX) and transition metal lines

    SciTech Connect

    Charatis, G.; Rockett, P.D.; Burkhalter, P.G.

    1983-01-01

    X-ray spectroscopy was performed in the 12 to 15 A region, recording L-shell lines from selected laser-irradiated transition metals. Line coincidences and near coincidences were identified between Fe, Cr, Mn, and Ni L-spectra, and F VIII and F IX K-shell lines. Wavelengths were determined to accuracies of 1 to 3 mA and will be utilized in selecting potential pumping candidates in future x-ray lasing schemes. High-resolution x-ray spectra were collected under controlled illumination and target conditions using 1.05 ..mu..m and 0.527 ..mu..m laser excitation with the KMS CHROMA laser.

  14. High Spectral Resolution X-ray Observation of Magnetic CVs: EX Hya

    SciTech Connect

    Luna, G; Brickhouse, N S; Mauche, C W

    2008-04-07

    In magnetic cataclysmic variables (CVs) the primary is a highly magnetized white dwarf (WD) whose field controls the accretion flow close to the WD, leading to a shock and accretion column that radiate chiefly in X-rays. We present preliminary results from a 500 ks Chandra HETG observation of the brightest magnetic CV EX Hya. From the observational dataset we are able to measure the temperature and density at different points of the cooling accretion column using sensitive line ratios. We also construct line-based light curves to search for rotational modulation of the X-ray emission.

  15. An outburst scenario for the X-ray spectral variability in 3C 111

    NASA Astrophysics Data System (ADS)

    Tombesi, F.; Reeves, J. N.; Reynolds, C. S.; García, J.; Lohfink, A.

    2013-09-01

    We present a combined Suzaku and Swift BAT broad-band E = 0.6-200 keV spectral analysis of three 3C 111 observations obtained in 2010. The data are well described with an absorbed power-law continuum and a weak (R ≃ 0.2) cold reflection component from distant material. We constrain the continuum cutoff at EC ≃ 150-200 keV, which is in accordance with X-ray Comptonization corona models and supports claims that the jet emission is only dominant at much higher energies. Fe XXVI Lyα emission and absorption lines are also present in the first and second observations, respectively. The modelling and interpretation of the emission line is complex and we explore three possibilities. If originating from ionized-disc reflection, this should be emitted at rin ≥ 50 rg or, in the lamp-post configuration, the illuminating source should be at a height of h ≥ 30 rg above the black hole. Alternatively, the line could be modelled with a hot collisionally ionized plasma with temperature kT = 22.0^{+6.1}_{-3.2} keV or a photoionized plasma with log ξ = 4.52^{+0.10}_{-0.16} erg s-1 cm and column density NH > 3 × 1023 cm-2. However, the first and second scenarios are less favoured on statistical and physical grounds, respectively. The blueshifted absorption line in the second observation can be modelled as an ultrafast outflow (UFO) with ionization parameter log ξ = 4.47^{+0.76}_{-0.04} erg s-1 cm, column density N_H = (5.3^{+1.8}_{-1.3})× 10^{22} cm-2 and outflow velocity vout = 0.104 ± 0.006c. Interestingly, the parameters of the photoionized emission model remarkably match those of the absorbing UFO, supporting the possibility that the same material could be responsible for both emission and absorption. We suggest an outburst scenario in which an accretion disc wind, initially lying out of the line of sight and observed in emission, then crosses our view to the source and it is observed in absorption as a mildly relativistic UFO.

  16. An Outburst Scenario for the X-ray Spectral Variability in 3C 111

    NASA Technical Reports Server (NTRS)

    Tombesi, Francesco; Reeves, J. N.; Reynolds, Christopher S.; Garcia, J.; Lohfink, A.

    2013-01-01

    We present a combined Suzaku and Swift BAT broad-band E=0.6-200 keV spectral analysis of three 3C 111 observations obtained in 2010. The data are well described with an absorbed power-law continuum and a weak (R approximately equal to 0.2) cold reflection component from distant material. We constrain the continuum cutoff at E(sub C) approximately equal to 150- 200 keV, which is in accordance with X-ray Comptonization corona models and supports claims that the jet emission is only dominant at much higher energies. Fe XXVI Ly alpha emission and absorption lines are also present in the first and second observations, respectively. The modelling and interpretation of the emission line is complex and we explore three possibilities. If originating from ionized disc reflection, this should be emitted at r(sub in) greater than or equal to 50 r(sub g) or, in the lamp-post configuration, the illuminating source should be at a height of h greater than or equal to 30 r(sub g) over the black hole. Alternatively, the line could be modeled with a hot collisionally ionized plasma with temperature kT = 22.0(sup +6.1)(sub -3.2) keV or a photo-ionized plasma with logXi=4.52(sup +0.10)(sub -0.16) erg per second cm, and column density N(sub H) greater than 3×10(sup 23) per square centimeter. However, the first and second scenarios are less favored on statistical and physical grounds, respectively. The blue-shifted absorption line in the second observation can be modelled as an ultra-fast outflow (UFO) with ionization parameter logXi=4.47(sup +0.76) (sub -0.04) erg per second cm, column density NH=(5.3(sup +1.8)(sub -1.3))×10(sup 22) per square centimeter and outflow velocity v(sub out) = 0.104+/-0.006c. Interestingly, the parameters of the photoionized emission model remarkably match those of the absorbing UFO, supporting the possibility that the same material could be responsible for both emission and absorption. We suggest an outburst scenario in which an accretion disc wind, initially lying out of the line of sight and observed in emission, then crosses our view to the source and it is observed in absorption as a mildly-relativistic UFO.

  17. Monitoring Long-Range Electron Transfer Pathways in Proteins by Stimulated Attosecond Broadband X-ray Raman Spectroscopy

    PubMed Central

    2015-01-01

    Long-range electron transfer (ET) is a crucial step in many energy conversion processes and biological redox reactions in living organisms. We show that newly developed X-ray pulses can directly probe the evolving oxidation states and the electronic structure around selected atoms with detail not available through conventional time-resolved infrared or optical techniques. This is demonstrated in a simulation study of the stimulated X-ray Raman (SXRS) signals in Re-modified azurin, which serves as a benchmark system for photoinduced ET in proteins. Nonlinear SXRS signals offer a direct novel window into the long-range ET mechanism. PMID:25400875

  18. Monitoring Long-Range Electron Transfer Pathways in Proteins by Stimulated Attosecond Broadband X-ray Raman Spectroscopy.

    PubMed

    Zhang, Yu; Biggs, Jason D; Govind, Niranjan; Mukamel, Shaul

    2014-11-01

    Long-range electron transfer (ET) is a crucial step in many energy conversion processes and biological redox reactions in living organisms. We show that newly developed X-ray pulses can directly probe the evolving oxidation states and the electronic structure around selected atoms with detail not available through conventional time-resolved infrared or optical techniques. This is demonstrated in a simulation study of the stimulated X-ray Raman (SXRS) signals in Re-modified azurin, which serves as a benchmark system for photoinduced ET in proteins. Nonlinear SXRS signals offer a direct novel window into the long-range ET mechanism. PMID:25400875

  19. The Need for X-Ray Spectroscopy

    NASA Technical Reports Server (NTRS)

    Winebarger, Amy R.; Cirtain, Jonathan; Kobayashi, Ken

    2011-01-01

    For over four decades, X-ray, EUV, and UV spectral observations have been used to measure physical properties of the solar atmosphere. During this time, there has been substantial improvement in the spectral, spatial, and temporal resolution of the observations for the EUV and UV wavelength ranges. At wavelengths below 100 Angstroms, however, observations of the solar corona with simultaneous spatial and spectral resolution are limited, and not since the late 1970's have spatially resolved solar X-ray spectra been measured. The soft-X-ray wavelength range is dominated by emission lines formed at high temperatures and provides diagnostics unavailable in any other wavelength range. In this presentation, we will discuss the important science questions that can be answered using spatially and spectrally resolved X-ray spectra.

  20. The Diffuse X-ray Spectrometer Experiment

    NASA Technical Reports Server (NTRS)

    Sanders, W. T.; Edgar, R. J.; Juda, M.; Kraushaar, W. L.; Mccammon, D.; Snowden, S. L.; Zhang, J.; Skinner, M. A.

    1992-01-01

    The Diffuse X-ray Spectrometer Experiment, or 'DXS', is designed to measure the spectrum of the low-energy diffuse X-ray background with about 10 eV energy resolution and 15-deg spatial resolution. During a 5-day Space Shuttle mission, DXS is to measure the spectrum of ten 15 x 15 deg regions lying along a single 150-deg-long great circle arc on the sky. DXS carries two large-area X-ray Bragg spectrometers for the 44-84 A wavelength range; these permit measurement of the wavelength spectrum of the cosmic low-energy diffuse X-ray background with good spectral resolution.

  1. Pseudopotential calculations of photoionization of atoms in the x-ray photon energy range and FEL beam monitor development

    NASA Astrophysics Data System (ADS)

    Chernov, V. E.; Dorofeev, D. L.; Elfimov, S. V.; Zon, B. A.; Gavrilov, G. E.; Naryshkin, Yu G.

    2015-03-01

    A pseudopotential model for calculation of atomic processes under interaction with hard x-ray photons is applied to calculation of Krypton photoionization cross sections by photons with energy in the 20-25 keV range. These cross sections, as well as the mean charge of the resulting ions calculated using the Monte Carlo simulation scheme, are in good agreement with the other theoretical calculations and with the experiment. The obtained results open the doors for new techniques in the design of gas-monitor detectors to control the intensity, coordinates and energy of x-ray free-electron laser (XFEL) beams in the hard x-ray photon energy range. First, Monte Carlo simulations of a scintillation detector application for gas-monitors have been performed.

  2. Temporal variations and spectral properties of the Be/X-ray pulsar GRO J1008—57 studied by INTEGRAL

    NASA Astrophysics Data System (ADS)

    Wang, Wei

    2014-05-01

    The spin period variations and hard X-ray spectral properties of the Be/X-ray pulsar GRO J1008—57 are studied with INTEGRAL observations during two outbursts in 2004 June and 2009 March. The pulsation periods of ~ 93.66 s in 2004 and ~ 93.73 s in 2009 are determined. Pulse profiles of GRO J1008—57 during outbursts are strongly energy dependent with a double-peaked profile from 3-7 keV and a single-peaked profile in hard X-rays above 7 keV. Combined with previous measurements, we find that GRO J1008—57 has undergone a spin-down trend from 1993-2009 with a rate of ~ 4.1 × 10-5 s d-1, and could have changed into a spin-up trend after 2009. We find a relatively soft spectrum in the early phase of the 2009 outburst with cutoff energy ~ 13 keV. Above a hard X-ray flux of ~ 10-9 erg cm-2 s-1, the spectra of GRO J1008—57 during outbursts need an enhanced hydrogen absorption with column density ~ 6 × 1022 cm-2. The observed dip-like pulse profile of GRO J1008—57 in soft X-ray bands could be caused by this intrinsic absorption. Around the outburst peaks, a possible cyclotron resonance scattering feature at ~ 74 keV is detected in the spectra of GRO J1008—57 which is consistent with the feature that was reported in MAXI/GSC observations, making the source a neutron star with the highest known magnetic field (~ 6.6 × 1012 G) among accreting X-ray pulsars. This marginal feature is supported by the present detections in GRO J1008—57 following the correlation between the fundamental line energies and cutoff energies in accreting X-ray pulsars. Finally we discovered two modulation periods at ~ 124.38 d and ~ 248.78 d using RXTE/ASM light curves of GRO J1008—57. Two flare peaks appearing in the folded light curve had different spectral properties. The normal outburst lasting 0.1 of an orbital phase had a hard spectrum and could not be significantly detected below 3 keV. The second flare lasting ten days showed a very soft spectrum without significant detections above 5 keV. GRO J1008—57 is a good candidate of an accreting system with an equatorial circumstellar disk around the companion star. The neutron star passing the disk of the Be star near periastron and apastron produces two X-ray flares. The soft spectral properties in the secondary flares still need further detailed studies with soft X-ray spectroscopy.

  3. A New Model for Spectral Formation in Accretion-Powered X-Ray Pulsars

    NASA Astrophysics Data System (ADS)

    Wolff, Michael T.; Becker, P. A.; Wolfram, K. D.

    2006-09-01

    Accretion-powered X-ray pulsars are among the most luminous X-ray sources in the Galaxy yet no satisfactory model for the formation of their observed X-ray spectra has emerged. We report on a self-consistent calculation of the spectrum emerging from a magnetically funneled pulsar accretion flow that includes a treatment of the bulk and thermal Comptonization occurring in a radiation-dominated shock. Using a rigorous eigenfunction expansion method, we obtain a closed-form expression for the Green's function describing the upscattering of monochromatic radiation injected into the flow. The Green's function is convolved with bremsstrahlung, cyclotron, and blackbody source terms to calculate the emergent photon spectrum. We show that energization of photons in the shock naturally produces a X-ray spectrum with a relatively flat continuum and a high-energy exponential cutoff. Finally, we demonstrate the good agreement of our model with the spectra of bright pulsars such as Her X-1 and Cen X-3. This research was funded by NASA and the Office of Naval Research.

  4. Spectral Resolution for Five-Element, Filtered, X-Ray Detector (XRD) Arrays Using the Methods of Backus and Gilbert

    SciTech Connect

    FEHL,DAVID LEE; BIGGS,F.; CHANDLER,GORDON A.; STYGAR,WILLIAM A.

    2000-01-17

    The generalized method of Backus and Gilbert (BG) is described and applied to the inverse problem of obtaining spectra from a 5-channel, filtered array of x-ray detectors (XRD's). This diagnostic is routinely fielded on the Z facility at Sandia National Laboratories to study soft x-ray photons ({le}2300 eV), emitted by high density Z-pinch plasmas. The BG method defines spectral resolution limits on the system of response functions that are in good agreement with the unfold method currently in use. The resolution so defined is independent of the source spectrum. For noise-free, simulated data the BG approximating function is also in reasonable agreement with the source spectrum (150 eV black-body) and the unfold. This function may be used as an initial trial function for iterative methods or a regularization model.

  5. Deconvolving X-ray spectral variability components in the Seyfert 1.5 NGC 3227

    SciTech Connect

    Arvalo, P.; Markowitz, A.

    2014-03-10

    We present the variability analysis of a 100 ks XMM-Newton observation of the Seyfert 1.5 active galaxy, NGC 3227. The observation found NGC 3227 in a period where its hard power-law component displayed remarkably little long-term variability. This lucky event allows us to clearly observe a soft spectral component undergoing a large-amplitude but slow flux variation. Using combined spectral and timing analysis, we isolate two independent variable continuum components and characterize their behavior as a function of timescale. Rapid and coherent variations throughout the 0.2-10 keV band reveal a spectrally hard (photon index ? ? 1.7-1.8) power law, dominating the observed variability on timescales of 30 ks and shorter. Another component produces coherent fluctuations in the 0.2-2 keV range and is much softer (? ? 3); it dominates the observed variability on timescales greater than 30 ks. Both components are viewed through the same absorbers identified in the time-averaged spectrum. The combined spectral and timing analysis breaks the degeneracy between models for the soft excess: it is consistent with a power-law or thermal Comptonized component but not with a blackbody or an ionized reflection component. We demonstrate that the rapid variability in NGC 3227 is intrinsic to continuum-emitting components and is not an effect of variable absorption.

  6. Developing a CCD camera with high spatial resolution for RIXS in the soft X-ray range

    NASA Astrophysics Data System (ADS)

    Soman, M. R.; Hall, D. J.; Tutt, J. H.; Murray, N. J.; Holland, A. D.; Schmitt, T.; Raabe, J.; Schmitt, B.

    2013-12-01

    The Super Advanced X-ray Emission Spectrometer (SAXES) at the Swiss Light Source contains a high resolution Charge-Coupled Device (CCD) camera used for Resonant Inelastic X-ray Scattering (RIXS). Using the current CCD-based camera system, the energy-dispersive spectrometer has an energy resolution (E/ΔE) of approximately 12,000 at 930 eV. A recent study predicted that through an upgrade to the grating and camera system, the energy resolution could be improved by a factor of 2. In order to achieve this goal in the spectral domain, the spatial resolution of the CCD must be improved to better than 5 μm from the current 24 μm spatial resolution (FWHM). The 400 eV-1600 eV energy X-rays detected by this spectrometer primarily interact within the field free region of the CCD, producing electron clouds which will diffuse isotropically until they reach the depleted region and buried channel. This diffusion of the charge leads to events which are split across several pixels. Through the analysis of the charge distribution across the pixels, various centroiding techniques can be used to pinpoint the spatial location of the X-ray interaction to the sub-pixel level, greatly improving the spatial resolution achieved. Using the PolLux soft X-ray microspectroscopy endstation at the Swiss Light Source, a beam of X-rays of energies from 200 eV to 1400 eV can be focused down to a spot size of approximately 20 nm. Scanning this spot across the 16 μm square pixels allows the sub-pixel response to be investigated. Previous work has demonstrated the potential improvement in spatial resolution achievable by centroiding events in a standard CCD. An Electron-Multiplying CCD (EM-CCD) has been used to improve the signal to effective readout noise ratio achieved resulting in a worst-case spatial resolution measurement of 4.5±0.2 μm and 3.9±0.1 μm at 530 eV and 680 eV respectively. A method is described that allows the contribution of the X-ray spot size to be deconvolved from these worst-case resolution measurements, estimating the spatial resolution to be approximately 3.5 μm and 3.0 μm at 530 eV and 680 eV, well below the resolution limit of 5 μm required to improve the spectral resolution by a factor of 2.

  7. Bismuth Sulfide Nanoflowers for Detection of X-rays in the Mammographic Energy Range

    NASA Astrophysics Data System (ADS)

    Nambiar, Shruti; Osei, Ernest K.; Yeow, John T. W.

    2015-03-01

    The increased use of diagnostic x-rays, especially in the field of medical radiology, has necessitated a significant demand for high resolution, real-time radiation detectors. In this regard, the photoresponse of bismuth sulfide (Bi2S3), an n-type semiconducting metal chalcogenide, to low energy x-rays has been investigated in this study. In recent years, several types of nanomaterials of Bi2S3 have been widely studied for optoelectronic and thermoelectric applications. However, photoresponse of Bi2S3 nanomaterials for dosimetric applications has not yet been reported. The photosensitivity of Bi2S3 with nanoscale ``flower-like'' structures was characterized under x-ray tube-potentials typically used in mammographic procedures. Both dark current and photocurrent were measured under varying x-ray doses, field sizes, and bias voltages for each of the tube potentials - 20, 23, 26 and 30 kV. Results show that the Bi2S3 nanoflowers instantaneously responded to even minor changes in the dose delivered. The photoresponse was found to be relatively high (few nA) at bias voltage as low as +1 V, and fairly repeatable for both short and long exposures to mammographic x-rays with minimal or no loss in sensitivity. The overall dose-sensitivity of the Bi2S3 nanoflowers was found to be similar to that of a micro-ionization chamber.

  8. Bismuth sulfide nanoflowers for detection of X-rays in the mammographic energy range.

    PubMed

    Nambiar, Shruti; Osei, Ernest K; Yeow, John T W

    2015-01-01

    The increased use of diagnostic x-rays, especially in the field of medical radiology, has necessitated a significant demand for high resolution, real-time radiation detectors. In this regard, the photoresponse of bismuth sulfide (Bi2S3), an n-type semiconducting metal chalcogenide, to low energy x-rays has been investigated in this study. In recent years, several types of nanomaterials of Bi2S3 have been widely studied for optoelectronic and thermoelectric applications. However, photoresponse of Bi2S3 nanomaterials for dosimetric applications has not yet been reported. The photosensitivity of Bi2S3 with nanoscale "flower-like" structures was characterized under x-ray tube-potentials typically used in mammographic procedures. Both dark current and photocurrent were measured under varying x-ray doses, field sizes, and bias voltages for each of the tube potentials - 20, 23, 26 and 30 kV. Results show that the Bi2S3 nanoflowers instantaneously responded to even minor changes in the dose delivered. The photoresponse was found to be relatively high (few nA) at bias voltage as low as +1 V, and fairly repeatable for both short and long exposures to mammographic x-rays with minimal or no loss in sensitivity. The overall dose-sensitivity of the Bi2S3 nanoflowers was found to be similar to that of a micro-ionization chamber. PMID:25801531

  9. Bismuth Sulfide Nanoflowers for Detection of X-rays in the Mammographic Energy Range

    PubMed Central

    Nambiar, Shruti; Osei, Ernest K.; Yeow, John T. W.

    2015-01-01

    The increased use of diagnostic x-rays, especially in the field of medical radiology, has necessitated a significant demand for high resolution, real-time radiation detectors. In this regard, the photoresponse of bismuth sulfide (Bi2S3), an n-type semiconducting metal chalcogenide, to low energy x-rays has been investigated in this study. In recent years, several types of nanomaterials of Bi2S3 have been widely studied for optoelectronic and thermoelectric applications. However, photoresponse of Bi2S3 nanomaterials for dosimetric applications has not yet been reported. The photosensitivity of Bi2S3 with nanoscale “flower-like” structures was characterized under x-ray tube-potentials typically used in mammographic procedures. Both dark current and photocurrent were measured under varying x-ray doses, field sizes, and bias voltages for each of the tube potentials – 20, 23, 26 and 30 kV. Results show that the Bi2S3 nanoflowers instantaneously responded to even minor changes in the dose delivered. The photoresponse was found to be relatively high (few nA) at bias voltage as low as +1 V, and fairly repeatable for both short and long exposures to mammographic x-rays with minimal or no loss in sensitivity. The overall dose-sensitivity of the Bi2S3 nanoflowers was found to be similar to that of a micro-ionization chamber. PMID:25801531

  10. Spectral variability in hard X-rays and discovery of a 13,5 years period in bright quasar 3C273

    NASA Astrophysics Data System (ADS)

    Manchanda, R.

    SPECTRAL VARIABILITY IN HARD X-RAYS AND DISCOVERY OF A 13.5 YEARS PERIOD IN BRIGHT QUASAR 3C273. R. K. Manchanda Tata Institute of Fundamental Research, Colaba, Mumbai-400005, India. ravi@tifr.res.in/Fax:+91-22-2152110 Among the large variety of active galactic nuclei, 3C 273 is the nearest quasi stellar object. The source has been studied in details in various energy bands and shows a large variety of morphological features. In the X-ray energy range 2-20 keV, the spectrum follows a power law with a spectral index of -1.5, however, the observed value of the spectral index in the 20-120 keV band shows a large variation. In the case of old archival data, the derived spectral index has a value between 1.5 and 2.2 while, the recent data from OSSE experiment showed a flat spectrum with index 0.8. Thus, to fit the GeV fluxes from the source, a break in the spectrum around 1 MeV has been proposed. In this paper we report the balloon-borne hard X-ray observations of 3C273 made with LASE instrument on Nov. 20, 1998 as a part of our continuing programme of balloon borne hard X-ray observations in the 20-200 keV band using high sensitivity Large Area Scintillation counter Experiment. Our data clearly show a steep spectrum in the 20-200 keV with spectral index a = -2.26+ 0.07 and its extrapolation can fit the GeV data. The presence of steep power law index is in complete contrast to earlier observation from OSSE. From a comparison with the available archival data of the source we have discovered that 50 keV flux from the source, shows very strong modulation with a period of about 13.5 years and which is also present at 100 keV and in the spectral index to a lesser degree. We discuss the periodicity in terms of precessing source geometry.

  11. Integration of the Two-Dimensional Power Spectral Density into Specifications for the X-ray Domain -- Problems and Opportunities

    SciTech Connect

    McKinney, Wayne R.; Howells, M. R.; Yashchuk, V. V.

    2008-09-30

    An implementation of the two-dimensional statistical scattering theory of Church and Takacs for the prediction of scattering from x-ray mirrors is presented with a graphical user interface. The process of this development has clarified several problems which are of significant interest to the synchrotron community. These problems have been addressed to some extent, for example, for large astronomical telescopes, and at the National Ignition Facility for normal incidence optics, but not in the synchrotron community for grazing incidence optics. Since it is based on the Power Spectral Density (PSD) to provide a description of the deviations from ideal shape of the surface, accurate prediction of the scattering requires an accurate estimation of the PSD. Specifically, the spatial frequency range of measurement must be the correct one for the geometry of use of the optic--including grazing incidence and coherence effects, and the modifications to the PSD of the Optical Transfer Functions (OTF) of the measuring instruments must be removed. A solution for removal of OTF effects has been presented previously, the Binary Pseudo-Random Grating. Typically, the frequency range of a single instrument does not cover the range of interest, requiring the stitching together of PSD estimations. This combination generates its own set of difficulties in two dimensions. Fitting smooth functions to two dimensional PSDs, particularly in the case of spatial non-isotropy of the surface, which is often the case for optics in synchrotron beam lines, can be difficult. The convenient, and physically accurate fractal for one dimension does not readily transfer to two dimensions. Finally, a completely statistical description of scattering must be integrated with a deterministic low spatial frequency component in order to completely model the intensity near the image. An outline for approaching these problems, and our proposed experimental program is given.

  12. A detailed X-ray investigation of ? Puppis. III. Spectral analysis of the whole RGS spectrum

    NASA Astrophysics Data System (ADS)

    Herv, A.; Rauw, G.; Naz, Y.

    2013-03-01

    Context. ? Pup is the X-ray brightest O-type star of the sky. This object was regularly observed with the RGS instrument onboard XMM-Newton for calibration purposes, which led to an unprecedented set of high-quality spectra. Aims: We have previously reduced and extracted this data set and integrated it into the most detailed high-resolution X-ray spectrum of any early-type star so far. Here we present the analysis of this spectrum, taking into account for the presence of structures in the stellar wind. Methods: For this purpose, we used our new modeling tool that allows fitting the entire spectrum with a multi-temperature plasma. We illustrate the impact of a proper treatment of the radial dependence of the X-ray opacity of the cool wind on the best-fit radial distribution of the temperature of the X-ray plasma. Results: The best-fit of the RGS spectrum of ? Pup is obtained assuming no porosity. Four plasma components at temperatures between 0.10 and 0.69 keV are needed to adequately represent the observed spectrum. Whilst the hardest emission is concentrated between ~3 and 4 R?, the softer emission starts already at 1.5 R? and extends to the outer regions of the wind. Conclusions: The inferred radial distribution of the plasma temperatures agrees rather well with theoretical expectations. The mass-loss rate and CNO abundances corresponding to our best-fit model also agree quite well with the results of recent studies of ? Pup in the UV and optical domain. Based on observations collected with XMM-Newton, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and the USA (NASA).

  13. High-Resolution Soft X-Ray Spectral Analysis in the CK Region of Titanium Carbide (TiC) using the DV-X alpha Molecular Orbital Method

    SciTech Connect

    Shimomura, Kenta; Muramatsu, Yasuji; Denlinger, Jonathan D.; Gullikson, Eric M.

    2008-10-31

    We used the DV-X alpha method to analyze the high-resolution soft X-ray emission and absorption spectra in the CK region of titanium carbide (TiC). The spectral profiles of the X-ray emission and absorption can be ssuscfucelly reproduced by the occupied and unoccupied density of states (DOS ), respectively, in the C2p orbitals of the center carbon atoms in a Ti62C63 cluster model, suggesting that the center carbon atom in a large cluster model expanded to the cubic-structured 53 (= 125) atoms provides sufficient DOS for the X-ray spectral analysis of rock-salt structured metal carbides.

  14. Revelations of X-ray spectral analysis of the enigmatic black hole binary GRS 1915+105

    NASA Astrophysics Data System (ADS)

    Peris, Charith; Remillard, Ronald A.; Steiner, James; Dil Vrtilek, Saeqa; Varniere, Peggy; Rodriguez, Jerome; Pooley, Guy

    2016-01-01

    Of the black hole binaries discovered thus far, GRS 1915+105 stands out as an exceptional source primarily due to its wild X-ray variability, the diversity of which has not been replicated in any other stellar-mass black hole. Although extreme variability is commonplace in its light-curve, about half of the observations of GRS1915+105 show fairly steady X-ray intensity. We report on the X-ray spectral behavior within these steady observations. Our work is based on a vast RXTE/PCA data set obtained on GRS 1915+105 during the course of its entire mission and 10 years of radio data from the Ryle Telescope, which overlap the X-ray data. We find that the steady observations within the X-ray data set naturally separate into two regions in a color-color diagram, which we refer to as steady-soft and steady-hard. GRS 1915+105 displays significant curvature in the Comptonization component within the PCA band pass suggesting significantly heating from a hot disk present in all states. A new Comptonization model 'simplcut' was developed in order to model this curvature to best effect. A majority of the steady-soft observations display a roughly constant inner radius; remarkably reminiscent of canonical soft state black hole binaries. In contrast, the steady-hard observations display a growing disk truncation that is correlated to the mass accretion rate through the disk, which suggests a magnetically truncated disk. A comparison of X-ray model parameters to the canonical state definitions show that almost all steady-soft observations match the criteria of either thermal or steep power law state, while the thermal state observations dominate the constant radius branch. A large portion (80%) of the steady-hard observations matches the hard state criteria when the disk fraction constraint is neglected. These results suggest that within the complexity of this source is a simpler underlying basis of states, which map to those observed in canonical black hole binaries. When represented in a color-color diagram, state assignments appear to map to ``A, B and C'' (Belloni et al. 2000) regions that govern fast variability cycles in GRS 1915+105 demonstrating a compelling link between short and long time scales in its phenomenology.

  15. A beam branching method for timing and spectral characterization of hard X-ray free-electron lasers

    PubMed Central

    Katayama, Tetsuo; Owada, Shigeki; Togashi, Tadashi; Ogawa, Kanade; Karvinen, Petri; Vartiainen, Ismo; Eronen, Anni; David, Christian; Sato, Takahiro; Nakajima, Kyo; Joti, Yasumasa; Yumoto, Hirokatsu; Ohashi, Haruhiko; Yabashi, Makina

    2016-01-01

    We report a method for achieving advanced photon diagnostics of x-ray free-electron lasers (XFELs) under a quasi-noninvasive condition by using a beam-splitting scheme. Here, we used a transmission grating to generate multiple branches of x-ray beams. One of the two primary diffracted branches (+1st-order) is utilized for spectral measurement in a dispersive scheme, while the other (−1st-order) is dedicated for arrival timing diagnostics between the XFEL and the optical laser pulses. The transmitted x-ray beam (0th-order) is guided to an experimental station. To confirm the validity of this timing-monitoring scheme, we measured the correlation between the arrival timings of the −1st and 0th branches. The observed error was as small as 7.0 fs in root-mean-square. Our result showed the applicability of the beam branching scheme to advanced photon diagnostics, which will further enhance experimental capabilities of XFEL. PMID:26958586

  16. A beam branching method for timing and spectral characterization of hard X-ray free-electron lasers.

    PubMed

    Katayama, Tetsuo; Owada, Shigeki; Togashi, Tadashi; Ogawa, Kanade; Karvinen, Petri; Vartiainen, Ismo; Eronen, Anni; David, Christian; Sato, Takahiro; Nakajima, Kyo; Joti, Yasumasa; Yumoto, Hirokatsu; Ohashi, Haruhiko; Yabashi, Makina

    2016-05-01

    We report a method for achieving advanced photon diagnostics of x-ray free-electron lasers (XFELs) under a quasi-noninvasive condition by using a beam-splitting scheme. Here, we used a transmission grating to generate multiple branches of x-ray beams. One of the two primary diffracted branches (+1st-order) is utilized for spectral measurement in a dispersive scheme, while the other (-1st-order) is dedicated for arrival timing diagnostics between the XFEL and the optical laser pulses. The transmitted x-ray beam (0th-order) is guided to an experimental station. To confirm the validity of this timing-monitoring scheme, we measured the correlation between the arrival timings of the -1st and 0th branches. The observed error was as small as 7.0 fs in root-mean-square. Our result showed the applicability of the beam branching scheme to advanced photon diagnostics, which will further enhance experimental capabilities of XFEL. PMID:26958586

  17. High-Latitude Emission of a Non-Power-Law Spectrum and Spectral Evolution of GRB X-Ray Tails

    SciTech Connect

    Zhang Binbin; Zhang Bing; Liang Enwei; Wang Xiangyu

    2009-05-25

    The apparent spectral evolution observed in the steep decay phase of many GRB earlyX-ray afterglows raises a great concern of the high-latitude ''curvature effect'' interpretation of this phase. However, previous curvature effect models only invoked a simple power law spectrum upon the cessation of the prompt internal emission. We investigate the 'curvature effect' model of a more general non-power-law spectrum and and test this model with the Swift/XRT observations By comparing the simulated lightcurves/spectra with the observed ones, we show that one can reproduce both the observed lightcurve and the apparent spectral evolution of GRB 050814 using a model invoking a cut-off power-law spectrum. This suggests that at least for some GRBs, the fast spectral evolution in the steep-decay phase can be explained by the curvature effect of a non-power-law spectrum.

  18. The 2005 Accretion Outburst in V1118 Ori: Evidence for A Spectral Change in X-rays

    NASA Astrophysics Data System (ADS)

    Audard, M.; Gdel, M.; Skinner, S. L.; Briggs, K. R.; Walter, F. M.; Stringfellow, G.; Hamilton, R. T.; Guinan, E. F.

    2005-12-01

    We present results from our X-ray monitoring campaign of the 2005 accretion outburst in the young low-mass star V1118 Ori. Optical and near-infrared photometry are presented as well. The X-ray data from early 2005 indicate that the X-ray flux and luminosity varied within a factor of two only, and were similar to the pre-outburst values measured in a serendipitous observation in 2002. Similarly, the hydrogen column density showed no evidence for significant excursions from the pre-outburst value of a few times 1021 cm-2. However, we observed a spectral change from a dominant hot plasma ( 25 MK) in 2002 and in January 2005 to a cooler plasma ( 8 MK) in February and March 2005. We argue that the closing in of the accretion disk during the outburst disrupted the hot magnetic loops high in the corona, whereas the lower cooler loops were less affected and became the dominant coronal component. We acknowledge support by NASA through Chandra award DD5-6029X and through XMM-Newton award NNG05GI96G to Columbia University. The Chandra X-ray Observatory Center is operated by the Smithsonian Astrophysical Observatory for and on behalf of the NASA under contract NAS8-03060. Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. The PSI group acknowledges support from the Swiss National Science Foundation (grants 20-58827.99 and 20-66875.01). Stony Brook's participation in SMARTS is made possible by support from the offices of the Provost and the Vice President for Research. We thank J. Allyn Smith, P. McGehee, J. Espinoza, and D. Gonzalez for doing the observations with the SMARTS telescopes. We also thank H. Tannanbaum, N. Schartel, and the VLA TOO panel for granting time to observe V1118 Ori.

  19. Numerical Solution of the Radiative Transfer Equation: X-Ray Spectral Formation from Cylindrical Accretion onto a Magnetized Neutron Star

    NASA Technical Reports Server (NTRS)

    Fairnelli, R.; Ceccobello, C.; Romano, P.; Titarchuk, L.

    2011-01-01

    Predicting the emerging X-ray spectra in several astrophysical objects is of great importance, in particular when the observational data are compared with theoretical models. This requires developing numerical routines for the solution of the radiative transfer equation according to the expected physical conditions of the systems under study. Aims. We have developed an algorithm solving the radiative transfer equation in the Fokker-Planck approximation when both thermal and bulk Comptonization take place. The algorithm is essentially a relaxation method, where stable solutions are obtained when the system has reached its steady-state equilibrium. Methods. We obtained the solution of the radiative transfer equation in the two-dimensional domain defined by the photon energy E and optical depth of the system pi using finite-differences for the partial derivatives, and imposing specific boundary conditions for the solutions. We treated the case of cylindrical accretion onto a magnetized neutron star. Results. We considered a blackbody seed spectrum of photons with exponential distribution across the accretion column and for an accretion where the velocity reaches its maximum at the stellar surface and at the top of the accretion column, respectively. In both cases higher values of the electron temperature and of the optical depth pi produce flatter and harder spectra. Other parameters contributing to the spectral formation are the steepness of the vertical velocity profile, the albedo at the star surface, and the radius of the accretion column. The latter parameter modifies the emerging spectra in a specular way for the two assumed accretion profiles. Conclusions. The algorithm has been implemented in the XPEC package for X-ray fitting and is specifically dedicated to the physical framework of accretion at the polar cap of a neutron star with a high magnetic field (approx > 10(exp 12) G). This latter case is expected to be of typical accreting systems such as X-ray pulsars and supergiant fast X ray transients.

  20. High-resolution single-shot spectral monitoring of hard x-ray free-electron laser radiation

    DOE PAGESBeta

    Makita, M.; Karvinen, P.; Zhu, D.; Juranic, P. N.; Grünert, J.; Cartier, S.; Jungmann-Smith, J. H.; Lemke, H. T.; Mozzanica, A.; Nelson, S.; et al

    2015-10-16

    We have developed an on-line spectrometer for hard x-ray free-electron laser (XFEL) radiation based on a nanostructured diamond diffraction grating and a bent crystal analyzer. Our method provides high spectral resolution, interferes negligibly with the XFEL beam, and can withstand the intense hard x-ray pulses at high repetition rates of >100 Hz. The spectrometer is capable of providing shot-to-shot spectral information for the normalization of data obtained in scientific experiments and optimization of the accelerator operation parameters. We have demonstrated these capabilities of the setup at the Linac Coherent Light Source, in self-amplified spontaneous emission mode at full energy ofmore » >1 mJ with a 120 Hz repetition rate, obtaining a resolving power of Ε/δΕ > 3 × 104. In conclusion, the device was also used to monitor the effects of pulse duration down to 8 fs by analysis of the spectral spike width.« less

  1. Application of maximum-entropy spectral estimation to deconvolution of XPS data. [X-ray Photoelectron Spectroscopy

    NASA Technical Reports Server (NTRS)

    Vasquez, R. P.; Klein, J. D.; Barton, J. J.; Grunthaner, F. J.

    1981-01-01

    A comparison is made between maximum-entropy spectral estimation and traditional methods of deconvolution used in electron spectroscopy. The maximum-entropy method is found to have higher resolution-enhancement capabilities and, if the broadening function is known, can be used with no adjustable parameters with a high degree of reliability. The method and its use in practice are briefly described, and a criterion is given for choosing the optimal order for the prediction filter based on the prediction-error power sequence. The method is demonstrated on a test case and applied to X-ray photoelectron spectra.

  2. Temporal behavior of unresolved transition array emission in water window soft x-ray spectral region from multiply charged ions

    NASA Astrophysics Data System (ADS)

    Dinh, Thanh-Hung; Suzuki, Yuhei; Arai, Goki; Li, Bowen; Dunne, Padraig; O'Sullivan, Gerry; Fujioka, Shinsuke; Hasegawa, Noboru; Kawachi, Tetsuya; Nishikino, Masaharu; Higashiguchi, Takeshi

    2015-09-01

    We have characterized the spectral structure and the temporal history of the laser-produced high-Z multi-charged ion plasmas for the efficient water window soft x-ray sources. Strong unresolved transition array emission was observed due to 4d-4f and 4f-5g transitions from Au, Pb, and Bi plasmas in the 280-700 eV photon energy region. The temporal behavior of the emission was essentially similar of that of the laser pulse with a slight delay between different transitions. These results provide feedback for accurate modeling of the atomic processes with the radiative hydrodynamic simulations.

  3. Monte Carlo comparison of x-ray and proton CT for range calculations of proton therapy beams

    NASA Astrophysics Data System (ADS)

    Arbor, N.; Dauvergne, D.; Dedes, G.; Létang, J. M.; Parodi, K.; Quiñones, C. T.; Testa, E.; Rit, S.

    2015-10-01

    Proton computed tomography (CT) has been described as a solution for imaging the proton stopping power of patient tissues, therefore reducing the uncertainty of the conversion of x-ray CT images to relative stopping power (RSP) maps and its associated margins. This study aimed to investigate this assertion under the assumption of ideal detection systems. We have developed a Monte Carlo framework to assess proton CT performances for the main steps of a proton therapy treatment planning, i.e. proton or x-ray CT imaging, conversion to RSP maps based on the calibration of a tissue phantom, and proton dose simulations. Irradiations of a computational phantom with pencil beams were simulated on various anatomical sites and the proton range was assessed on the reference, the proton CT-based and the x-ray CT-based material maps. Errors on the tissue’s RSP reconstructed from proton CT were found to be significantly smaller and less dependent on the tissue distribution. The imaging dose was also found to be much more uniform and conformal to the primary beam. The mean absolute deviation for range calculations based on x-ray CT varies from 0.18 to 2.01 mm depending on the localization, while it is smaller than 0.1 mm for proton CT. Under the assumption of a perfect detection system, proton range predictions based on proton CT are therefore both more accurate and more uniform than those based on x-ray CT.

  4. Spectral Modeling of the Charge-exchange X-Ray Emission from M82

    NASA Astrophysics Data System (ADS)

    Zhang, Shuinai; Wang, Q. Daniel; Ji, Li; Smith, Randall K.; Foster, Adam R.; Zhou, Xin

    2014-10-01

    It has been proposed that the charge-exchange (CX) process at the interface between hot and cool interstellar gases could contribute significantly to the observed soft X-ray emission in star-forming galaxies. We analyze the XMM-Newton/reflection grating spectrometer (RGS) spectrum of M82 using a newly developed CX model combined with a single-temperature thermal plasma to characterize the volume-filling hot gas. The CX process is largely responsible for not only the strongly enhanced forbidden lines of the K? triplets of various He-like ions but also good fractions of the Ly? transitions of C VI (~87%), O VIII, and N VII (gsim50%) as well. In total about a quarter of the X-ray flux in the RGS 6-30 band originates in the CX. We infer an ion incident rate of 3 1051 s-1 undergoing CX at the hot and cool gas interface and an effective area of the interface of ~2 1045 cm2 that is one order of magnitude larger than the cross section of the global biconic outflow. With the CX contribution accounted for, the best-fit temperature of the hot gas is 0.6 keV, and the metal abundances are approximately solar. We further show that the same CX/thermal plasma model also gives an excellent description of the EPIC-pn spectrum of the outflow Cap, projected at 11.6 kpc away from the galactic disk of M82. This analysis demonstrates that the CX is potentially an important contributor to the X-ray emission from starburst galaxies and also an invaluable tool to probe the interface astrophysics.

  5. Spectral modeling of the charge-exchange X-ray emission from M82

    SciTech Connect

    Zhang, Shuinai; Ji, Li; Zhou, Xin; Wang, Q. Daniel; Smith, Randall K.; Foster, Adam R.

    2014-10-10

    It has been proposed that the charge-exchange (CX) process at the interface between hot and cool interstellar gases could contribute significantly to the observed soft X-ray emission in star-forming galaxies. We analyze the XMM-Newton/reflection grating spectrometer (RGS) spectrum of M82 using a newly developed CX model combined with a single-temperature thermal plasma to characterize the volume-filling hot gas. The CX process is largely responsible for not only the strongly enhanced forbidden lines of the Kα triplets of various He-like ions but also good fractions of the Lyα transitions of C VI (∼87%), O VIII, and N VII (≳50%) as well. In total about a quarter of the X-ray flux in the RGS 6-30 Å band originates in the CX. We infer an ion incident rate of 3 × 10{sup 51} s{sup –1} undergoing CX at the hot and cool gas interface and an effective area of the interface of ∼2 × 10{sup 45} cm{sup 2} that is one order of magnitude larger than the cross section of the global biconic outflow. With the CX contribution accounted for, the best-fit temperature of the hot gas is 0.6 keV, and the metal abundances are approximately solar. We further show that the same CX/thermal plasma model also gives an excellent description of the EPIC-pn spectrum of the outflow Cap, projected at 11.6 kpc away from the galactic disk of M82. This analysis demonstrates that the CX is potentially an important contributor to the X-ray emission from starburst galaxies and also an invaluable tool to probe the interface astrophysics.

  6. X-ray structural and spectral study of the cobalt(II) chloride complex with papaverine

    SciTech Connect

    Sabirov, V.Kh.; Struchkov, Yu.T.; Nava, E.U.

    1994-05-01

    A complex of cobalt(II) chloride with papaverine is characterized by x-ray diffraction method (autodiffractometer, 1917 reflections, R = 0.080). Crystals are tetragonal, a = b = 18.393(2) {angstrom}, c = 12.396(4) {angstrom}, Z = 4, space group P{bar 4}/n. The crystal structure is composed of tetrahedral [CoCl{sub 4}]{sup 2-} anions situated in a special position on the {bar 4} axis, cations of the protonated papaverine, and two types of water molecules. The structure exhibits short hydrogen-bond-type contacts C-H...Cl between anions and cations and C-H...O between cations.

  7. The Hubble Space Telescope observations of X-ray nova Muscae 1991 and its spectral evolution

    NASA Technical Reports Server (NTRS)

    Cheng, F. H.; Horne, Keith; Panagia, N.; Shrader, C. R.; Gilmozzi, R.; Paresce, F.; Lund, N.

    1992-01-01

    Hubble Space Telescope Faint Object Spectrograph (FOS) Faint Object Camera (FOC) and observations of Nova Muscae 1991 obtained on May 14-15, 1991 are presented and discussed. A nearly featureless continuum with broad 2200 A absorption feature and no Balmer jump is found. The FOS spectrum is modeled, including previous multiepoch IUE, optical, and X-ray data using a simple blackbody accretion disk model. It is found that the mass transfer rate decays exponentially with a characteristic time of about 43 days. The cooling front predicted by the disk instability model should have been observable, but was not seen.

  8. BeppoSAX and RXTE Spectral Study of the Low-mass X-Ray Binary 4U 1705-44: Spectral Hardening during the Banana Branch

    NASA Astrophysics Data System (ADS)

    Seifina, Elena; Titarchuk, Lev; Shrader, Chris; Shaposhnikov, Nikolai

    2015-08-01

    We analyze the X-ray spectra of the atoll 4U 1705-44 when the source undergoes the island-banana state transition. We use the RXTE and BeppoSAX observations for this analysis. We demonstrate that the broadband energy spectral distributions for all evolutinary states can be fitted by a model consisting of two Comptonized components. One arises from the seed photons coming from a neutron star (NS) atmosphere at a temperature {{kT}}{{s}1}≲ 1.5 keV (herein Comptb1), and a second results from the seed photons of {T}{{s}2} ˜ 1.1-1.3 keV coming from the disk (herein Comptb2). We found that we needed to add a low-temperature blackbody and an iron-line (Gaussian) component to the model in order to obtain high-quality fits. The data analysis using this model indicates that the power-law photon index {{{Γ }}}1 of our model is always about 2, independently of the spectral state. Another parameter, {{{Γ }}}2, demonstrates a two-phase behavior depending on the spectral state. {{{Γ }}}2 is quasi-constant at {{{Γ }}}2˜ 2 when the electron temperature {{kT}}{{e}}(2)\\lt 80 keV, and {{{Γ }}}2 is less than 2, in the range of 1.3\\lt {{{Γ }}}2\\lt 2, when {{kT}}{{e}}(2)\\gt 80 keV. This phase is similar to that previously found in the Z-source Sco X-1. We interpret the decreasing index phase using a model in which a super-Eddington radiation pressure from the NS causes an expansion of the Compton cloud similar to that found previously in Sco X-1 during the Flaring branch.

  9. Correlations between X-Ray Spectral Characteristics and Quasi-Periodic Oscillations in Scorpius X-1

    NASA Astrophysics Data System (ADS)

    Bradshaw, Charles F.; Titarchuk, Lev; Kuznetsov, Sergey

    2007-07-01

    Correlations between 1-10 Hz quasi-periodic oscillations (QPOs) and spectral power-law index have been reported for black hole (BH) candidate sources and one neutron star source, 4U 1728-34. An examination of QPO frequency and index relationships in Sco X-1 is reported here. We discover that Sco X-1, representing Z-source groups, can be adequately modeled by a simple two-component model of Compton up-scattering with a soft photon electron temperature of about 0.4 keV, plus an Iron K line. The results show a strong correlation between spectral power-law index and kHz QPOs. Because Sco X-1 radiates near the Eddington limit, one can infer that the geometrical configuration of the Compton cloud (CC) is quasi-spherical from high radiation pressure in the CC. Thus, we conclude that the high Thomson optical depth of the Compton cloud, in the range of ~5-6 from the best-fit model parameters, is consistent with the neutron star's surface being obscured by material. Moreover, a spin frequency of Sco X-1 is likely suppressed due to photon scattering off CC electrons. In addition, we demonstrate how the power spectrum evolves when Sco X-1 transitions from the horizontal branch to the normal branch.

  10. Polycrystalline lead iodide films produced by solution evaporation and tested in the mammography X-ray energy range

    NASA Astrophysics Data System (ADS)

    Condeles, J. F.; Mulato, M.

    2016-02-01

    Lead iodide polycrystalline films have been deposited on corning glass substrates using solution evaporation in oven. Films 6 μm-thick were obtained with full coverage of the substrates as verified by scanning electron microscopy. Some pin-holes were observable. X-ray diffraction revealed a crystalline structure corresponding to the 4 H-PbI2 polytype formation. Polarized Raman scattering experiments indicated a lamellar structure. Anisotropy was also investigated using depolarization ratio calculations. The optical and electrical properties of the samples were investigated using photoluminescence and dark conductivity as a function of temperature, respectively. Activation energies of 0.10 up to 0.89 eV were related to two main electrical transport mechanisms. Films were also exposed to X-ray irradiation in the mammography X-ray energy range. The detector produced was also exposed to X-ray from 5 mR up to 1450 mR. A linear response was observed as a function of dose with a slope of 0.52 nA/mm2 per mR.

  11. X-ray absorption spectral studies of copper (II) mixed ligand complexes

    NASA Astrophysics Data System (ADS)

    Soni, B.; Dar, Davood Ah; Shrivastava, B. D.; Prasad, J.; Srivastava, K.

    2014-09-01

    X-ray absorption spectra at the K-edge of copper have been studied in two copper mixed ligand complexes, one having tetramethyethylenediamine (tmen) and the other having tetraethyethylenediamine (teen) as one of the ligands. The spectra have been recorded at BL-8 dispersive extended X-ray absorption fine structure (EXAFS) beamline at the 2.5 GeV INDUS- 2 synchrotron, RRCAT, Indore, India. The data obtained has been processed using the data analysis program Athena. The energy of the K-absorption edge, chemical shift, edge-width and shift of the principal absorption maximum in the complexes have been determined and discussed. The values of these parameters have been found to be approximately the same in both the complexes indicating that the two complexes possess similar chemical environment around the copper metal atom. The chemical shift has been utilized to estimate effective nuclear charge on the absorbing atom. The normalized EXAFS spectra have been Fourier transformed. The position of the first peak in the Fourier transform gives the value of first shell bond length, which is shorter than the actual bond length because of energy dependence of the phase factors in the sine function of the EXAFS equation. This distance is thus the phase- uncorrected bond length. Bond length has also been determined by Levy's, Lytle's and Lytle, Sayers and Stern's (LSS) methods. The results obtained from LSS and the Fourier transformation methods are comparable with each other, since both are phase uncorrected bond lengths.

  12. Soft X-ray spectral features in the Seyfert 1 Galaxy NGC4051

    NASA Technical Reports Server (NTRS)

    Mihara, Tatehiro; Matsuoka, Masaru; Mushotzky, Richard F.; Kunieda, Hideyo; Otani, Chiko; Miyamoto, Sigenori; Yamauchi, Makoto

    1994-01-01

    We report ASCA observations of NGC 4051 during the PV phase. The time averaged X-ray spectrum is not well fit by a simple power law with an iron K-emission line and shows significant absorption-edge features most probably due to O VII and O VIII and a strong soft excess. This is the first direct measurement of edges in the spectrum of this object and confirms that the X-ray spectrum of NGC 4051 is modified by a 'warm' absorbing gas. The best fit underlying power law index in the 0.4-10 keV band is 1.88. A power law modified by a warm absorber model can partly explain the apparent soft excess and qualitatively fit the SIS spectrum. However, the addition of a black body of kT approx. = 0.1 keV improves the fit considerably. The 90% upper limit on the width of the iron line is 460 eV full width at half maximum (FWHM). Applying the fluorescent iron line model from an accretion disk gives an upper limit of 20 deg for the inclination of the disk.

  13. X-ray dual energy spectral parameter optimization for bone Calcium/Phosphorus mass ratio estimation

    NASA Astrophysics Data System (ADS)

    Sotiropoulou, P. I.; Fountos, G. P.; Martini, N. D.; Koukou, V. N.; Michail, C. M.; Valais, I. G.; Kandarakis, I. S.; Nikiforidis, G. C.

    2015-09-01

    Calcium (Ca) and Phosphorus (P) bone mass ratio has been identified as an important, yet underutilized, risk factor in osteoporosis diagnosis. The purpose of this simulation study is to investigate the use of effective or mean mass attenuation coefficient in Ca/P mass ratio estimation with the use of a dual-energy method. The investigation was based on the minimization of the accuracy of Ca/P ratio, with respect to the Coefficient of Variation of the ratio. Different set-ups were examined, based on the K-edge filtering technique and single X-ray exposure. The modified X-ray output was attenuated by various Ca/P mass ratios resulting in nine calibration points, while keeping constant the total bone thickness. The simulated data were obtained considering a photon counting energy discriminating detector. The standard deviation of the residuals was used to compare and evaluate the accuracy between the different dual energy set-ups. The optimum mass attenuation coefficient for the Ca/P mass ratio estimation was the effective coefficient in all the examined set-ups. The variation of the residuals between the different set-ups was not significant.

  14. Learning to Apply Metrology Principles to the Measurement of X-ray Intensities in the 500 eV to 110 keV Energy Range

    SciTech Connect

    Haugh, M. J.; Pond, T.; Silbernagel, C.; Torres, P.; Marlett, K.; Goldin, F.; Cyr, S.

    2011-02-08

    National Security Technologies, LLC (NSTec), Livermore Operations, has two optical radiation calibration laboratories accredited by “the National Voluntary Laboratories Accreditation Program (NVLAP) which is the accrediting body of” the National Institute of Standards and Technology (NIST), and is now working towards accreditation for its X-ray laboratories. NSTec operates several laboratories with X-ray sources that generate X-rays in the energy range from 50 eV to 115 keV. These X-ray sources are used to characterize and calibrate diagnostics and diagnostic components used by the various national laboratories, particularly for plasma analysis on the Lawrence Livermore National Laboratory (LLNL) National Ignition Facility (NIF). Because X-ray photon flux measurement methods that can be accredited, i.e., traceable to NIST, have not been developed for sources operating in these energy ranges, NSTec, NIST, and the National Voluntary Accreditation Program (NVLAP) together have defined a path toward the development and validation of accredited metrology methods for X-ray energies. The methodology developed for the high energy X-ray (HEX) Laboratory was NSTec’s starting point for X-ray metrology accreditation and will be the basis for the accredited processes in the other X-ray laboratories. This paper will serve as a teaching tool, by way of this example using the NSTec X-ray sources, for the process and methods used in developing an accredited traceable metrology.

  15. Kilohertz-range flash x-ray generator utilizing a triode in conjunction with an extremely hot cathode

    NASA Astrophysics Data System (ADS)

    Sato, E.; Shikoda, A.; Kimura, S.; Sagae, M.; Isobe, H.; Takahashi, K.; Tamakawa, Y.; Yanagisawa, T.; Honda, K.; Yokota, Y.

    1991-09-01

    The construction and the fundamental studies of a kilohertz-range flash x-ray generator having a triode in conjunction with an extremely hot cathode are described. This generator consisted of the following components: a constant-high voltage power supply, an energy storage condenser of 100 nF, a constant high-voltage power supply for regulating an initial grid voltage of -1.6 kV, a grid pulser, and an x-ray tube. The x-ray tube was of an enclosed-triode type and consisted of the following major parts: an anode rod made of copper, a plane anode tip (target) made of tungsten, a focusing electrode made of iron, a hot cathode (filament) made of tungsten, a grid made from tungsten wire, and a glass tube body. The energy storage condenser was charged from 50 to 70 kV, and the electric charges in the condenser were discharged repetitively to the x-ray tube by the grid electrode driven by the grid pulser. The temperature of the filament was about 2000 K, and the cathode current was primarily controlled by the grid voltage and its value was less than 1.2 A. The pulse widths were about 1 μs and the maximum repetitive frequency was about 2.0 kHz. The x-ray intensity was 19.7 nC/kg at 0.5 m per pulse with a peak grid voltage of 1.0 kV and a condenser charged voltage of 70 kV.

  16. Probing the X-ray absorber structure in the AGN population through fast spectral variability

    NASA Astrophysics Data System (ADS)

    Ballo, L.; Severgnini, P.; Moretti, A.; Braito, V.; Vignali, C.; Caccianiga, A.; Campana, S.; Della Ceca, R.; Maccacaro, T.; Fanali, R.

    2014-07-01

    One of the hot topics in modern astrophysics is the variability of absorbers in Seyfert 2 galaxies, suggesting that these structures could be more complex and located at much smaller distances than the conventional obscuring torus. However, in this framework a statistically representative sample of well-studied sources is still missing. We recently started a project aimed at finding more examples of these objects in order to study the physical properties of the X-ray absorber on a larger statistical basis, and to evaluate the frequency of rapid absorption variability among the active galactic nuclei (AGN) population. Here I will present our project: the source selection, based on the exploitation of the BAT AGN catalogue plus the XRT data archive; few preliminary results on particularly significant individual objects; and the future developments, in particular the expectations for Mrk 915, for which new XMM-Newton + NuSTAR observations have been awarded in the last XMM-Newton call.

  17. Spectral analysis of x-ray emission created by intense laser irradiation of copper materials.

    PubMed

    Huntington, C M; Kuranz, C C; Malamud, G; Drake, R P; Park, H-S; Maddox, B R

    2012-10-01

    We have measured the x-ray emission, primarily from K(?),K(?), and He(?) lines, of elemental copper foil and "foam" targets irradiated with a mid-10(16) W/cm(2) laser pulse. The copper foam at 0.1 times solid density is observed to produce 50% greater He(?) line emission than copper foil, and the measured signal is well-fit by a sum of three synthetic spectra generated by the atomic physics code FLYCHK. Additionally, spectra from both targets reveal characteristic inner shell K(?) transitions from hot electron interaction with the bulk copper. However, only the larger-volume foam target produced significant K(?) radiation, confirming a lower bulk temperature in the higher volume sample. PMID:23126936

  18. Spectral analysis of x-ray emission created by intense laser irradiation of copper materialsa)

    NASA Astrophysics Data System (ADS)

    Huntington, C. M.; Kuranz, C. C.; Malamud, G.; Drake, R. P.; Park, H.-S.; Maddox, B. R.

    2012-10-01

    We have measured the x-ray emission, primarily from K?,K?, and He? lines, of elemental copper foil and "foam" targets irradiated with a mid-1016 W/cm2 laser pulse. The copper foam at 0.1 times solid density is observed to produce 50% greater He? line emission than copper foil, and the measured signal is well-fit by a sum of three synthetic spectra generated by the atomic physics code FLYCHK. Additionally, spectra from both targets reveal characteristic inner shell K? transitions from hot electron interaction with the bulk copper. However, only the larger-volume foam target produced significant K? radiation, confirming a lower bulk temperature in the higher volume sample.

  19. Spectral analysis of x-ray emission created by intense laser irradiation of copper materials

    SciTech Connect

    Huntington, C. M.; Kuranz, C. C.; Drake, R. P.; Malamud, G.; Park, H.-S.; Maddox, B. R.

    2012-10-15

    We have measured the x-ray emission, primarily from K{sub {alpha}},K{sub {beta}}, and He{sub {alpha}} lines, of elemental copper foil and 'foam' targets irradiated with a mid-10{sup 16} W/cm{sup 2} laser pulse. The copper foam at 0.1 times solid density is observed to produce 50% greater He{sub {alpha}} line emission than copper foil, and the measured signal is well-fit by a sum of three synthetic spectra generated by the atomic physics code FLYCHK. Additionally, spectra from both targets reveal characteristic inner shell K{sub {alpha}} transitions from hot electron interaction with the bulk copper. However, only the larger-volume foam target produced significant K{sub {beta}} radiation, confirming a lower bulk temperature in the higher volume sample.

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

    SciTech Connect

    Hernandez, Andrew M.; Boone, John M.

    2014-04-15

    Purpose: Monte Carlo methods were used to generate lightly filtered high resolution x-ray spectra spanning from 20 kV to 640 kV. Methods: X-ray spectra were simulated for a conventional tungsten anode. The Monte Carlo N-Particle eXtended radiation transport code (MCNPX 2.6.0) was used to produce 35 spectra over the tube potential range from 20 kV to 640 kV, and cubic spline interpolation procedures were used to create piecewise polynomials characterizing the photon fluence per energy bin as a function of x-ray tube potential. Using these basis spectra and the cubic spline interpolation, 621 spectra were generated at 1 kV intervals from 20 to 640 kV. The tungsten anode spectral model using interpolating cubic splines (TASMICS) produces minimally filtered (0.8 mm Be) x-ray spectra with 1 keV energy resolution. The TASMICS spectra were compared mathematically with other, previously reported spectra. Results: Using pairedt-test analyses, no statistically significant difference (i.e., p > 0.05) was observed between compared spectra over energy bins above 1% of peak bremsstrahlung fluence. For all energy bins, the correlation of determination (R{sup 2}) demonstrated good correlation for all spectral comparisons. The mean overall difference (MOD) and mean absolute difference (MAD) were computed over energy bins (above 1% of peak bremsstrahlung fluence) and over all the kV permutations compared. MOD and MAD comparisons with previously reported spectra were 2.7% and 9.7%, respectively (TASMIP), 0.1% and 12.0%, respectively [R. Birch and M. Marshall, “Computation of bremsstrahlung x-ray spectra and comparison with spectra measured with a Ge(Li) detector,” Phys. Med. Biol. 24, 505–517 (1979)], 0.4% and 8.1%, respectively (Poludniowski), and 0.4% and 8.1%, respectively (AAPM TG 195). The effective energy of TASMICS spectra with 2.5 mm of added Al filtration ranged from 17 keV (at 20 kV) to 138 keV (at 640 kV); with 0.2 mm of added Cu filtration the effective energy was 9 keV at 20 kV and 169 keV at 640 kV. Conclusions: Ranging from 20 kV to 640 kV, 621 x-ray spectra were produced and are available at 1 kV tube potential intervals. The spectra are tabulated at 1 keV intervals. TASMICS spectra were shown to be largely equivalent to published spectral models and are available in spreadsheet format for interested users by emailing the corresponding author (JMB)

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

    PubMed Central

    Hernandez, Andrew M.; Boone, John M.

    2014-01-01

    Purpose: Monte Carlo methods were used to generate lightly filtered high resolution x-ray spectra spanning from 20 kV to 640 kV. Methods: X-ray spectra were simulated for a conventional tungsten anode. The Monte Carlo N-Particle eXtended radiation transport code (MCNPX 2.6.0) was used to produce 35 spectra over the tube potential range from 20 kV to 640 kV, and cubic spline interpolation procedures were used to create piecewise polynomials characterizing the photon fluence per energy bin as a function of x-ray tube potential. Using these basis spectra and the cubic spline interpolation, 621 spectra were generated at 1 kV intervals from 20 to 640 kV. The tungsten anode spectral model using interpolating cubic splines (TASMICS) produces minimally filtered (0.8 mm Be) x-ray spectra with 1 keV energy resolution. The TASMICS spectra were compared mathematically with other, previously reported spectra. Results: Using paired t-test analyses, no statistically significant difference (i.e., p > 0.05) was observed between compared spectra over energy bins above 1% of peak bremsstrahlung fluence. For all energy bins, the correlation of determination (R2) demonstrated good correlation for all spectral comparisons. The mean overall difference (MOD) and mean absolute difference (MAD) were computed over energy bins (above 1% of peak bremsstrahlung fluence) and over all the kV permutations compared. MOD and MAD comparisons with previously reported spectra were 2.7% and 9.7%, respectively (TASMIP), 0.1% and 12.0%, respectively [R. Birch and M. Marshall, Computation of bremsstrahlung x-ray spectra and comparison with spectra measured with a Ge(Li) detector, Phys. Med. Biol. 24, 505517 (1979)], 0.4% and 8.1%, respectively (Poludniowski), and 0.4% and 8.1%, respectively (AAPM TG 195). The effective energy of TASMICS spectra with 2.5 mm of added Al filtration ranged from 17 keV (at 20 kV) to 138 keV (at 640 kV); with 0.2 mm of added Cu filtration the effective energy was 9 keV at 20 kV and 169 keV at 640 kV. Conclusions: Ranging from 20 kV to 640 kV, 621 x-ray spectra were produced and are available at 1 kV tube potential intervals. The spectra are tabulated at 1 keV intervals. TASMICS spectra were shown to be largely equivalent to published spectral models and are available in spreadsheet format for interested users by emailing the corresponding author (JMB). PMID:24694149

  2. Warm Absorbers in X-rays (WAX), a comprehensive high resolution grating spectral study of a sample of Seyfert galaxies

    NASA Astrophysics Data System (ADS)

    Laha, S.; Guainazzi, M.; Dewangan, G.; Chakravorty, S.; Kembhavi, A.

    2014-07-01

    We present results from a homogeneous analysis of the broadband 0.3-10 keV CCD resolution as well as of soft X-ray high-resolution grating spectra of a hard X-ray flux-limited sample of 26 Seyfert galaxies observed with XMM-Newton. We could put a strict lower limit on the detection fraction of 50%. We find a gap in the distribution of the ionisation parameter in the range 0.5X-rays. The WA parameters show no correlation among themselves, except for one case. The shallow slope of the log? versus logv_{out} linear regression (0.12 0.03) is inconsistent with the scaling laws predicted by radiation or magneto-hydrodynamic-driven winds. Our results suggest also that WA and Ultra Fast Outflows (UFOs) do not represent extreme manifestation of the same astrophysical system.

  3. SWIFT OBSERVATIONS OF THE 2006 OUTBURST OF THE RECURRENT NOVA RS OPHIUCHI. III. X-RAY SPECTRAL MODELING

    SciTech Connect

    Vaytet, N. M. H.; Page, K. L.; Beardmore, A. P.; Bode, M. F. E-mail: tim.obrien@manchester.ac.uk E-mail: mfb@astro.livjm.ac.uk

    2011-10-10

    Following the Swift X-ray observations of the 2006 outburst of the recurrent nova RS Ophiuchi, we developed hydrodynamical models of mass ejection from which the forward shock velocities were used to estimate the ejecta mass and velocity. In order to further constrain our model parameters, we present synthetic X-ray spectra from our hydrodynamical calculations, which we compare to the Swift data. An extensive set of simulations was carried out to find a model that best fits the spectra up to 100 days after outburst. We find a good fit at high energies but require additional absorption to match the low energy emission. We estimate the ejecta mass to be in the range (2-5) x 10{sup -7} M{sub sun} and the ejection velocity to be greater than 6000 km s{sup -1} (and probably closer to 10, 000 km s{sup -1}). We also find that estimates of shock velocity derived from gas temperatures via standard model fits to the X-ray spectra are much lower than those of the true shock velocities.

  4. X-ray spectral modelling of the AGN obscuring region in the CDFS: Bayesian model selection and catalogue

    NASA Astrophysics Data System (ADS)

    Buchner, J.; Georgakakis, A.; Nandra, K.; Hsu, L.; Rangel, C.; Brightman, M.; Merloni, A.; Salvato, M.; Donley, J.; Kocevski, D.

    2014-04-01

    Context. Aims: Active galactic nuclei are known to have complex X-ray spectra that depend on both the properties of the accreting super-massive black hole (e.g. mass, accretion rate) and the distribution of obscuring material in its vicinity (i.e. the "torus"). Often however, simple and even unphysical models are adopted to represent the X-ray spectra of AGN, which do not capture the complexity and diversity of the observations. In the case of blank field surveys in particular, this should have an impact on e.g. the determination of the AGN luminosity function, the inferred accretion history of the Universe and also on our understanding of the relation between AGN and their host galaxies. Methods: We develop a Bayesian framework for model comparison and parameter estimation of X-ray spectra. We take into account uncertainties associated with both the Poisson nature of X-ray data and the determination of source redshift using photometric methods. We also demonstrate how Bayesian model comparison can be used to select among ten different physically motivated X-ray spectral models the one that provides a better representation of the observations. This methodology is applied to X-ray AGN in the 4 Ms Chandra Deep Field South. Results: For the ~350 AGN in that field, our analysis identifies four components needed to represent the diversity of the observed X-ray spectra: (1) an intrinsic power law; (2) a cold obscurer which reprocesses the radiation due to photo-electric absorption, Compton scattering and Fe-K fluorescence; (3) an unabsorbed power law associated with Thomson scattering off ionised clouds; and (4) Compton reflection, most noticeable from a stronger-than-expected Fe-K line. Simpler models, such as a photo-electrically absorbed power law with a Thomson scattering component, are ruled out with decisive evidence (B > 100). We also find that ignoring the Thomson scattering component results in underestimation of the inferred column density, NH, of the obscurer. Regarding the geometry of the obscurer, there is strong evidence against both a completely closed (e.g. sphere), or entirely open (e.g. blob of material along the line of sight), toroidal geometry in favour of an intermediate case. Conclusions: Despite the use of low-count spectra, our methodology is able to draw strong inferences on the geometry of the torus. Simpler models are ruled out in favour of a geometrically extended structure with significant Compton scattering. We confirm the presence of a soft component, possibly associated with Thomson scattering off ionised clouds in the opening angle of the torus. The additional Compton reflection required by data over that predicted by toroidal geometry models, may be a sign of a density gradient in the torus or reflection off the accretion disk. Finally, we release a catalogue of AGN in the CDFS with estimated parameters such as the accretion luminosity in the 2-10 keV band and the column density, NH, of the obscurer. Appendices and Figs. 6, 9-11 are available in electronic form at http://www.aanda.orgCatalogue and software are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/564/A125

  5. Calibration of remote mineralogy algorithms using modal analyses of Apollo soils by X-ray diffraction and microscopic spectral imaging

    NASA Astrophysics Data System (ADS)

    Crites, S. T.; Taylor, J.; Martel, L.; Lucey, P. G.; Blake, D. F.

    2012-12-01

    We have launched a project to determine the modal mineralogy of over 100 soils from all Apollo sites using quantitative X-ray diffraction (XRD) and microscopic hyperspectral imaging at visible, near-IR and thermal IR wavelengths. The two methods are complementary: XRD is optimal for obtaining the major mineral modes because its measurement is not limited to the surfaces of grains, whereas the hyperspectral imaging method allows us to identify minerals present even down to a single grain, well below the quantitative detection limit of XRD. Each soil is also sent to RELAB to obtain visible, near-IR, and thermal-IR reflectance spectra. The goal is to use quantitative mineralogy in comparison with spectra of the same soils and with remote sensing data of the sampling stations to improve our ability to extract quantitative mineralogy from remote sensing observations. Previous groups have demonstrated methods for using lab mineralogy to validate remote sensing. The LSCC pioneered the method of comparing mineralogy to laboratory spectra of the same soils (Pieters et al. 2002); Blewett et al. (1997) directly compared remote sensing results for sample sites with lab measurements of representative soils from those sites. We are building upon the work of both groups by expanding the number of soils measured to 128, with an emphasis on immature soils to support recent work studying fresh exposures like crater central peaks, and also by incorporating the recent high spatial and spectral resolution data sets over expanded wavelength ranges (e.g. Diviner TIR, M3 hyperspectral VNIR) not available at the time of the previous studies. We have thus far measured 32 Apollo 16 soils using quantitative XRD and are continuing with our collection of soils from the other landing sites. We have developed a microscopic spectral imaging system that includes TIR, VIS, and NIR capabilities and have completed proof-of-concept scans of mineral separates and preliminary lunar soil scans with plans to begin systematically scanning lunar soils in all three wavelength ranges this fall. As an example in using the laboratory data as a validation and improvement tool for remote mineralogy algorithms, we have applied the Apollo 16 XRD results to remote mineralogy of the site obtained using the method of Lucey and Greenhagen (2012). The algorithm was applied to Kaguya MI and Chandrayaan-1 M3 VNIR data with constraints from the Diviner Christiansen Feature (CF). Our study identified potential for improvement in the application of a space weathering correction to the CF data in the Lucey and Greenhagen method, and also highlighted the importance of incorporating microscopic spectral imaging for more precise determination of low-abundance mafic minerals in the plagioclase-dominated highlands. Next steps include incorporating modes from microscopic spectral imaging and applying our methods to sites with greater compositional variability beginning with Apollo 17. Blewett et al. (1997) JGR, 102, E7, doi:10.1029/97JE01505 Lucey and Greenhagen (2012) 43rd LPSC, abstract 1736 Pieters et al. (2002) Icarus 155, 285-298

  6. Versatile high-repetition-rate phase-locked chopper system for fast timing experiments in the vacuum ultraviolet and x-ray spectral region

    SciTech Connect

    Plogmaker, Stefan; Johansson, Erik M. J.; Rensmo, Haakan; Feifel, Raimund; Siegbahn, Hans; Linusson, Per; Eland, John H. D.; Baker, Neville

    2012-01-15

    A novel light chopper system for fast timing experiments in the vacuum-ultraviolet (VUV) and x-ray spectral region has been developed. It can be phase-locked and synchronized with a synchrotron radiation storage ring, accommodating repetition rates in the range of {approx}8 to {approx}120 kHz by choosing different sets of apertures and subharmonics of the ring frequency (MHz range). Also the opening time of the system can be varied from some nanoseconds to several microseconds to meet the needs of a broad range of applications. Adjusting these parameters, the device can be used either for the generation of single light pulses or pulse packages from a microwave driven, continuous He gas discharge lamp or from storage rings which are otherwise often considered as quasi-continuous light sources. This chopper can be utilized for many different kinds of experiments enabling, for example, unambiguous time-of-flight (TOF) multi-electron coincidence studies of atoms and molecules excited by a single light pulse as well as time-resolved visible laser pump x-ray probe electron spectroscopy of condensed matter in the valence and core level region.

  7. Characterizing the evolving X-ray spectral features during a superburst from 4U 1636-536

    SciTech Connect

    Keek, L.; Ballantyne, D. R.; Kuulkers, E.; Strohmayer, T. E.

    2014-07-10

    Recent studies have shown that runaway thermonuclear burning of material accreted onto neutron stars, i.e., Type I X-ray bursts, may affect the accretion disk. We investigate this by performing a detailed time-resolved spectral analysis of the superburst from 4U 1636-536 observed in 2001 with the Rossi X-Ray Timing Explorer. Superbursts are attributed to the thermonuclear burning of carbon, and are approximately 1000 times more energetic than the regular short Type I bursts. This allows us to study detailed spectra for over 11 ks, compared to, at most, 100 s for regular bursts. A feature is present in the superburst spectra around 6.4 keV that is well fit with an emission line and an absorption edge, suggestive of reflection of the superburst off the accretion disk. The line and edge parameters evolve over time: the edge energy decreases from 9.4 keV at the peak to 8.1 keV in the tail, and both features become weaker in the tail. This is only the second superburst for which this has been detected and shows that this behavior is present even without strong radius expansion. Furthermore, we find the persistent flux more than doubles during the superburst and returns to the pre-superburst value in the tail. The combination of reflection features and increased persistent emission indicates that the superburst had a strong impact on the inner accretion disk and it emphasizes that X-ray bursts provide a unique probe of accretion physics.

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

    NASA Astrophysics Data System (ADS)

    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.

  9. On the Nature of the mHz X-Ray QPOs from ULX M82 X-1: Evidence for Timing-Spectral (anti) Correlation

    NASA Technical Reports Server (NTRS)

    Pasham, Dheeraj R.; Strohmayer, Tod E.

    2013-01-01

    Using all the archival XMM-Newton X-ray (3-10 keV) observations of the ultraluminous X-ray source (ULX) M82 X-1 we searched for a correlation between its variable mHz quasi-periodic oscillation (QPO) frequency and its energy spectral power-law index. These quantities are known to correlate in stellar mass black holes (StMBHs) exhibiting Type-C QPOs (approx 0.2-15 Hz). The detection of such a correlation would strengthen the identification of its mHz QPOs as Type-C and enable a more reliable mass estimate by scaling its QPO frequencies to those of Type-C QPOs in StMBHs of known mass. We resolved the count rates of M82 X-1 and a nearby bright ULX (source 5/X42.3+59) through surface brightness modeling and identify observations in which M82 X-1 was at least as bright as source 5. Using only those observations, we detect QPOs in the frequency range of 36-210 mHz during which the energy spectral power-law index varied from 1.7-2.2. Interestingly, we find evidence for an anti-correlation (Pearsons correlation coefficient = -0.95) between the power-law index and the QPO centroid frequency. While such an anti-correlation is observed in StMBHs at high Type-C QPO frequencies (approx 5-15 Hz), the frequency range over which it holds in StMBHs is significantly smaller (factor of approx 1.5-3) than the QPO range reported here from M82 X-1 (factor of 6). However, it remains possible that contamination from source 5 can bias our result. Joint Chandra/XMM-Newton observations in the future can resolve this problem and confirm the timing-spectral anti-correlation reported here.

  10. Characterizations of MCP performance in the hard x-ray range (6-25 keV)

    NASA Astrophysics Data System (ADS)

    Wu, Ming; Moy, Ken; Kruschwitz, Craig; Rochau, Greg

    2014-11-01

    MCP detector performance at hard x-ray energies from 6 to 25 keV was recently investigated using NSLS beamline X15A at BNL. Measurements were made with an NSTec Gen-II (H-CA-65) framing camera, based on a Photonis MCP with 10 ?m in diameter pores, 12 ?m center-center spacing, an L/D ratio of 46, and a bias angle of 8. The MCP characterizations were focused on (1) energy and angle dependent sensitivity, (2) energy and angle dependent spatial resolution, (3) energy dependent gain performance, and (4) energy dependent dynamic range. These measurement corroborated simulation results using a Monte Carlo model that included hard x-ray interactions and the subsequent electron cascade in the MCP.

  11. Characterizations of MCP performance in the hard x-ray range (6–25 keV)

    SciTech Connect

    Wu, Ming Rochau, Greg; Moy, Ken; Kruschwitz, Craig

    2014-11-15

    MCP detector performance at hard x-ray energies from 6 to 25 keV was recently investigated using NSLS beamline X15A at BNL. Measurements were made with an NSTec Gen-II (H-CA-65) framing camera, based on a Photonis MCP with ∼10 μm in diameter pores, ∼12 μm center-center spacing, an L/D ratio of 46, and a bias angle of 8°. The MCP characterizations were focused on (1) energy and angle dependent sensitivity, (2) energy and angle dependent spatial resolution, (3) energy dependent gain performance, and (4) energy dependent dynamic range. These measurement corroborated simulation results using a Monte Carlo model that included hard x-ray interactions and the subsequent electron cascade in the MCP.

  12. Energy dependence of photon-induced K? and K? x-ray production cross-sections for some elements with 42?Z?68 in the energy range 38-80 keV

    NASA Astrophysics Data System (ADS)

    Seven, Sabriye; Erdo?an, Hasan

    2015-12-01

    The energy dependence of photon-induced K? and K? x-ray production cross-sections for Mo, Ru, Pd, In, Sb, Cs, La, Pr, Sm, Tb and Er elements has been studied in the energy range of 38-80 keV with secondary excitation method. K x-ray intensities were measured using Energy Dispersive X-Ray Fluorescence (EDXRF) Spectrometry. The measurements have been made by observing the x-ray emissions, with the help of HPGe detector coupled with a multichannel analyzer. The areas of the K? and K? spectral peaks, as well as the net peak areas, have been determined by a fitting process. The measured K? and K? x-ray production cross-sections have been compared with calculated theoretical values in this energy regime. The results have been plotted versus excitation energy. The present experimental K? and K? x-ray production cross-section values for all the elements were in general agreement with the theoretical values calculated using photoionization cross-sections, fluorescence yields and fractional rates based on Hartree-Slater potentials.

  13. A Broad-band Spectral and Timing Study of the X-Ray Binary System Centaurus X-3

    NASA Technical Reports Server (NTRS)

    Audley, Michael Damian

    1998-01-01

    This dissertation describes a multi-mission investigation of the high mass X-ray binary pulsar Centaurus X-3. Cen X-3 was observed with the Broad Band X-Ray Telescope (BBXRT) in December 1990. This was the first high-resolution solid state X-ray spectrometer to cover the iron K fluorescence region. The Fe K emission feature was resolved into two components for the first time. A broad 6.7 keV feature was found to be a blend of lines from Fe XXI-Fe XXVI with energies ranging from 6.6 to 6.9 keV due to photoionization of the companion's stellar wind. A narrow line at 6.4 keV due to fluorescence of iron in relatively low ionization states was also found. The quasi-periodic oscillations (QPO) at about 40 mHz were used to estimate the surface magnetic field of Cen X-3 as approx. 2.6 x 10(exp 12) G and to predict that there should be a cyclotron scattering resonance absorption feature (CSRF) near 30 keV. In order to further resolve the iron line complex and to investigate the pulse-phase dependence of the iron line intensities, Cen X-3 was observed with the Advanced Satellite for Cosmology and Astrophysics (ASCA). Using ASCA's state-of-the-art non-dispersive X-ray spectrometers the 6.4 keV fluorescent iron line was found to be pulsing while the intensities of the 6.7 and 6.9 keV recombination lines do not vary with pulse phase. This confirms that the 6.4 keV line is due to reflection by relatively neutral matter close to the neutron star while the recombination lines originate in the extended stellar wind. The continuum spectrum was found to be modified by reflection from matter close to the neutron star. Observations with the EXOSAT GSPC were used to search for a CSRF. The EXOSAT spectra were consistent with the presence of a CSRF but an unambiguous detection was not possible because of a lack of sensitivity at energies higher than the cyclotron energy. Cen X-3 was then observed with the Rossi X-Ray Timing Explorer (RXTE) and evidence for a CSRF at 25.1 +/- 0.3 keV was found. This corresponds to a magnetic field of (2.16 +/- 0.03) X 10(exp 12) G and is consistent with the value obtained from the QPO analysis.

  14. SU-E-T-301: Spectral Comparison of the Xoft and Zeiss 50 KVp X-Ray Systems

    SciTech Connect

    Kelley, L; Rusch, T; Holt, R

    2014-06-01

    Purpose: To compare x-ray spectra of the 50 kVp Xoft Axxent™ and Zeiss INTRABEAM™ x-ray sources after filtration by saline-filled balloons applicators or spherical polymer applicators, respectively. Methods: Measurements were made for 3.5, 4.0 and 5.0 cm diameter applicators using an AmpTek model XR-100T-CdTe cadmium telluride spectrometer with 100 μm diameter collimating aperture and model PX4 digital pulse processor. Spectra were then corrected for escape processes using AmpTek XRF-FP Escape software. Both Axxent and INTRABEAM sources were operated at 50 kV and 40 μA to eliminate pulse saturation. The balloon or spherical applicator was placed in a centering fixture in contact with the collimator cap. The distance through the collimator housing from the applicator surface to the spectrometer's beryllium entrance window was nominally 52mm. Approximately 500,000 counts were collected for each spectrum. Results: Measured spectra in all cases had a broad Bremsstrahlung continuum with subtle differences in characteristic low energy x-rays lines from the different materials used for the anode thin films and substrates. After corrections for escape events average energies were calculated for spectra emerging from applicators. The average energies were 28.2 ±0.3 keV, 29.0±0.7 keV, and 31.7±0.9 keV for the 3.5, 4.0 and 5.0 cm diameter applicators, respectively. Differences in average energies ranged from 2.0 to 5.6% for these diameters. The mean energies of the spectra are more dependent on balloon size than on the delivery system used. Conclusion: Energy spectra at the surfaces of 3.5, 4.0 and 5.0 cm diameter applicators were measured for the Axxent and INTRABEAM x-ray systems were using a Cd-Te spectrometer. The average energies of the two x-ray systems for comparable applicator sizes were within 5.6%, and as little as 0.6 keV difference for the smaller applicator size. Research sponsored by Xoft, a subsidiary of ICAD.

  15. Multiple-view spectrally resolved x-ray imaging observations of polar-direct-drive implosions on OMEGA

    SciTech Connect

    Mancini, R. C.; Johns, H. M.; Joshi, T.; Mayes, D.; Nagayama, T.; Hsu, S. C.; Baumgaertel, J. A.; Cobble, J.; Krasheninnikova, N. S.; Bradley, P. A.; Hakel, P.; Murphy, T. J.; Schmitt, M. J.; Shah, R. C.; Tregillis, I. L.; Wysocki, F. J.

    2014-12-15

    We present spatially, temporally, and spectrally resolved narrow- and broad-band x-ray images of polar-direct-drive (PDD) implosions on OMEGA. These self-emission images were obtained during the deceleration phase and bang time using several multiple monochromatic x-ray imaging instruments fielded along two or three quasi-orthogonal lines-of-sight, including equatorial and polar views. The instruments recorded images based on K-shell lines from a titanium tracer located in the shell as well as continuum emission. These observations constitute the first such data obtained for PDD implosions. The image data show features attributed to laser imprinting and zero-order hydrodynamics. Equatorial-view images show a “double bun” structure that is consistent with synthetic images obtained from post-processing 2D and 3D radiation-hydrodynamic simulations of the experiment. Polar-view images show a pentagonal, petal pattern that correlates with the PDD laser illumination used on OMEGA, thus revealing a 3D aspect of PDD OMEGA implosions not previously observed. Differences are noted with respect to a PDD experiment performed at National Ignition Facility.

  16. Multiple-view spectrally resolved x-ray imaging observations of polar-direct-drive implosions on OMEGA

    NASA Astrophysics Data System (ADS)

    Mancini, R. C.; Johns, H. M.; Joshi, T.; Mayes, D.; Nagayama, T.; Hsu, S. C.; Baumgaertel, J. A.; Cobble, J.; Krasheninnikova, N. S.; Bradley, P. A.; Hakel, P.; Murphy, T. J.; Schmitt, M. J.; Shah, R. C.; Tregillis, I. L.; Wysocki, F. J.

    2014-12-01

    We present spatially, temporally, and spectrally resolved narrow- and broad-band x-ray images of polar-direct-drive (PDD) implosions on OMEGA. These self-emission images were obtained during the deceleration phase and bang time using several multiple monochromatic x-ray imaging instruments fielded along two or three quasi-orthogonal lines-of-sight, including equatorial and polar views. The instruments recorded images based on K-shell lines from a titanium tracer located in the shell as well as continuum emission. These observations constitute the first such data obtained for PDD implosions. The image data show features attributed to laser imprinting and zero-order hydrodynamics. Equatorial-view images show a "double bun" structure that is consistent with synthetic images obtained from post-processing 2D and 3D radiation-hydrodynamic simulations of the experiment. Polar-view images show a pentagonal, petal pattern that correlates with the PDD laser illumination used on OMEGA, thus revealing a 3D aspect of PDD OMEGA implosions not previously observed. Differences are noted with respect to a PDD experiment performed at National Ignition Facility.

  17. Miocrowave spectral imaging, H-alpha and hard X-ray observations of a solar limb flare

    NASA Technical Reports Server (NTRS)

    Wang, H.; Gary, D. E.; Lim, J.; Schwartz, R. A.

    1994-01-01

    We compare the microwave, H-alpha, and hard X-ray observations for a west limb C7.3 flare that occurred at 17:10 UT, 1992 June 26. H-alpha movies were obtained at Big Bear Solar Observatory. Before the onset of the flare, overexposed H-alpha images show the complicated flux loop structure above the limb. Material was observed to descend along the loops toward the site where the flare occurred hours later. Using the five-antenna solar array at Owens Valley Radio Observatory, we obtain two-dimensional maps of flare emission from 1.4 to 14 GHz. In all three temporal peaks of the microwave bursts, the maps show the same characteristics. The peak low-frequency emission comes from the top of one bundle of the H-alpha loops and gradually shifts to the foot-point of the loops (the location of H-alpha flare) as the frequency increases. The location of the emission peak shifts 88 sec between 1 and 14 GHz. Seventy percent of the shift occurs between 1 and 5 GHz. The locus of the shift of the emission peak follows the shape of an H-alpha surge that occurred after the flare. For each point along the locus, we create the microwave brightness temperature spectrum and compare the radio-derived electron distribution with that derived from the high-resolution hard X-ray spectra measured with Burst and Transient Source Experiment (BATSE) on board the Compton Gamma Ray Observatory (CGRO). We find that the peak frequency changes from approximately 3 GHz at the loop top to approximately 7 GHz at the footprint, presumably due to the increase of the magnetic field from approximately 160 GHz at the loop top to approximately 300 G at the footpoint. The high-frequency slope of the microwave power-law spectrum decreases from approximately 10 at the loop top to approximately 5 at the footprint due to a change in the energy distribution of the dominant electrons. The microwave brightness temperature spectral index predicted by the BATSE power-law hard X-ray spectra agrees with the measured value only at the footpoint. At the loop top, the emission may be thermal gyrosynchrotron with a temperature of 3.5 x 10(exp 7) K, which is likely to correspond to the superhot component seen in the hard X-ray emission.

  18. Measurement of high-energy (10-60 keV) x-ray spectral line widths with eV accuracy.

    PubMed

    Seely, J F; Glover, J L; Hudson, L T; Ralchenko, Y; Henins, Albert; Pereira, N; Feldman, U; Di Stefano, C A; Kuranz, C C; Drake, R P; Chen, Hui; Williams, G J; Park, J

    2014-11-01

    A high resolution crystal spectrometer utilizing a crystal in transmission geometry has been developed and experimentally optimized to measure the widths of emission lines in the 10-60 keV energy range with eV accuracy. The spectrometer achieves high spectral resolution by utilizing crystal planes with small lattice spacings (down to 2d = 0.099 nm), a large crystal bending radius and Rowland circle diameter (965 mm), and an image plate detector with high spatial resolution (60 ?m in the case of the Fuji TR image plate). High resolution W L-shell and K-shell laboratory test spectra in the 10-60 keV range and Ho K-shell spectra near 47 keV recorded at the LLNL Titan laser facility are presented. The Ho K-shell spectra are the highest resolution hard x-ray spectra recorded from a solid target irradiated by a high-intensity laser. PMID:25430194

  19. Measurement of high-energy (1060 keV) x-ray spectral line widths with eV accuracy

    SciTech Connect

    Seely, J. F. Feldman, U.; Glover, J. L.; Hudson, L. T.; Ralchenko, Y.; Henins, Albert; Pereira, N.; Di Stefano, C. A.; Kuranz, C. C.; Drake, R. P.; Chen, Hui; Williams, G. J.; Park, J.

    2014-11-15

    A high resolution crystal spectrometer utilizing a crystal in transmission geometry has been developed and experimentally optimized to measure the widths of emission lines in the 1060 keV energy range with eV accuracy. The spectrometer achieves high spectral resolution by utilizing crystal planes with small lattice spacings (down to 2d = 0.099 nm), a large crystal bending radius and Rowland circle diameter (965 mm), and an image plate detector with high spatial resolution (60 ?m in the case of the Fuji TR image plate). High resolution W L-shell and K-shell laboratory test spectra in the 1060 keV range and Ho K-shell spectra near 47 keV recorded at the LLNL Titan laser facility are presented. The Ho K-shell spectra are the highest resolution hard x-ray spectra recorded from a solid target irradiated by a high-intensity laser.

  20. Measurement of high-energy (10-60 keV) x-ray spectral line widths with eV accuracya)

    NASA Astrophysics Data System (ADS)

    Seely, J. F.; Glover, J. L.; Hudson, L. T.; Ralchenko, Y.; Henins, Albert; Pereira, N.; Feldman, U.; Di Stefano, C. A.; Kuranz, C. C.; Drake, R. P.; Chen, Hui; Williams, G. J.; Park, J.

    2014-11-01

    A high resolution crystal spectrometer utilizing a crystal in transmission geometry has been developed and experimentally optimized to measure the widths of emission lines in the 10-60 keV energy range with eV accuracy. The spectrometer achieves high spectral resolution by utilizing crystal planes with small lattice spacings (down to 2d = 0.099 nm), a large crystal bending radius and Rowland circle diameter (965 mm), and an image plate detector with high spatial resolution (60 ?m in the case of the Fuji TR image plate). High resolution W L-shell and K-shell laboratory test spectra in the 10-60 keV range and Ho K-shell spectra near 47 keV recorded at the LLNL Titan laser facility are presented. The Ho K-shell spectra are the highest resolution hard x-ray spectra recorded from a solid target irradiated by a high-intensity laser.

  1. Range verification for eye proton therapy based on proton-induced x-ray emissions from implanted metal markers

    NASA Astrophysics Data System (ADS)

    La Rosa, Vanessa; Kacperek, Andrzej; Royle, Gary; Gibson, Adam

    2014-06-01

    Metal fiducial markers are often implanted on the back of the eye before proton therapy to improve target localization and reduce patient setup errors. We aim to detect characteristic x-ray emissions from metal targets during proton therapy to verify the treatment range accuracy. Initially gold was chosen for its biocompatibility properties. Proton-induced x-ray emissions (PIXE) from a 15 mm diameter gold marker were detected at different penetration depths of a 59 MeV proton beam at the CATANA proton facility at INFN-LNS (Italy). The Monte Carlo code Geant4 was used to reproduce the experiment and to investigate the effect of different size markers, materials, and the response to both mono-energetic and fully modulated beams. The intensity of the emitted x-rays decreases with decreasing proton energy and thus decreases with depth. If we assume the range to be the depth at which the dose is reduced to 10% of its maximum value and we define the residual range as the distance between the marker and the range of the beam, then the minimum residual range which can be detected with 95% confidence level is the depth at which the PIXE peak is equal to 1.96 ?bkg, which is the standard variation of the background noise. With our system and experimental setup this value is 3 mm, when 20 GyE are delivered to a gold marker of 15 mm diameter. Results from silver are more promising. Even when a 5 mm diameter silver marker is placed at a depth equal to the range, the PIXE peak is 2.1 ?bkg. Although these quantitative results are dependent on the experimental setup used in this research study, they demonstrate that the real-time analysis of the PIXE emitted by fiducial metal markers can be used to derive beam range. Further analysis are needed to demonstrate the feasibility of the technique in a clinical setup.

  2. A Comprehensive Spectral Analysis of the X-Ray Pulsar 4U 1907+09 from Two Observations with the Suzaku X-Ray Observatory

    NASA Technical Reports Server (NTRS)

    Rivers, Elizabeth; Markowitz, Alex; Pottschmidt, Katja; Roth, Stefanie; Barragan, Laura; Furst, Felix; Suchy, Slawomir; Kreykenbohm, Ingo; Wilms, Jorn; Rothschild, Richard

    2009-01-01

    We present results from two observations of the wind-accreting X-ray pulsar 4U 1907+09 using the Suzaku observatory, The broadband time-averaged spectrum allows us to examine the continuum emission of the source and the cyclotron resonance scattering feature at approx. 19 keV. Additionally, using the narrow CCD response of Suzaku near 6 ke V allows us to study in detail the Fe K bandpass and to quantify the Fe Kp line for this source for the first time. The source is absorbed by fully-covering material along the line of sight with a column density of N(sub H) approx. 2 x 10(exp 22)/sq cm, consistent with a wind accreting geometry, and a high Fe abundance (approx. 3 - 4 x solar). Time and phase-resolved analyses allow us to study variations in the source spectrum. In particular, dips found in the 2006 observation which are consistent with earlier observations occur in the hard X-ray bandpass, implying a variation of the whole continuum rather than occultation by intervening material, while a dip near the end of the 2007 observation occurs mainly in the lower energies implying an increase in NH along the line of sight, perhaps indicating clumpiness in the stellar wind

  3. A COMPREHENSIVE SPECTRAL ANALYSIS OF THE X-RAY PULSAR 4U 1907+09 FROM TWO OBSERVATIONS WITH THE SUZAKU X-RAY OBSERVATORY

    SciTech Connect

    Rivers, Elizabeth; Markowitz, Alex; Suchy, Slawomir; Rothschild, Richard; Pottschmidt, Katja; Roth, Stefanie; Barragan, Laura; Fuerst, Felix; Kreykenbohm, Ingo; Wilms, Joern

    2010-01-20

    We present results from two observations of the wind-accreting X-ray pulsar 4U 1907+09 using the Suzaku Observatory. The broadband time-averaged spectrum allows us to examine the continuum emission of the source and the cyclotron resonance scattering feature at approx19 keV. Additionally, using the narrow CCD response of Suzaku near 6 keV allows us to study in detail the Fe K bandpass and to quantify the Fe Kbeta line for this source for the first time. The source is absorbed by fully covering material along the line of sight with a column density of N{sub H} approx 2 x 10{sup 22} cm{sup -2}, consistent with a wind-accreting geometry, and a high Fe abundance (approx3-4 times solar). Time- and phase-resolved analyses allow us to study variations in the source spectrum. In particular, dips found in the 2006 observation which are consistent with earlier observations occur in the hard X-ray bandpass, implying a variation of the whole continuum rather than occultation by intervening material, while a dip near the end of the 2007 observation occurs mainly in the lower energies implying an increase in N{sub H} along the line of sight, perhaps indicating clumpiness in the stellar wind.

  4. X-ray structural studies of quinone reductase 2 nanomolar range inhibitors

    SciTech Connect

    Pegan, Scott D.; Sturdy, Megan; Ferry, Gilles; Delagrange, Philippe; Boutin, Jean A.; Mesecar, Andrew D.

    2011-09-06

    Quinone reductase 2 (QR2) is one of two members comprising the mammalian quinone reductase family of enzymes responsible for performing FAD mediated reductions of quinone substrates. In contrast to quinone reductase 1 (QR1) which uses NAD(P)H as its co-substrate, QR2 utilizes a rare group of hydride donors, N-methyl or N-ribosyl nicotinamide. Several studies have linked QR2 to the generation of quinone free radicals, several neuronal degenerative diseases, and cancer. QR2 has been also identified as the third melatonin receptor (MT3) through in cellulo and in vitro inhibition of QR2 by traditional MT3 ligands, and through recent X-ray structures of human QR2 (hQR2) in complex with melatonin and 2-iodomelatonin. Several MT3 specific ligands have been developed that exhibit both potent in cellulo inhibition of hQR2 nanomolar, affinity for MT3. The potency of these ligands suggest their use as molecular probes for hQR2. However, no definitive correlation between traditionally obtained MT3 ligand affinity and hQR2 inhibition exists limiting our understanding of how these ligands are accommodated in the hQR2 active site. To obtain a clearer relationship between the structures of developed MT3 ligands and their inhibitory properties, in cellulo and in vitro IC{sub 50} values were determined for a representative set of MT3 ligands (MCA-NAT, 2-I-MCANAT, prazosin, S26695, S32797, and S29434). Furthermore, X-ray structures for each of these ligands in complex with hQR2 were determined allowing for a structural evaluation of the binding modes of these ligands in relation to the potency of MT3 ligands.

  5. Task-based weights for photon counting spectral x-ray imaging

    SciTech Connect

    Bornefalk, Hans

    2011-11-15

    Purpose: To develop a framework for taking the spatial frequency composition of an imaging task into account when determining optimal bin weight factors for photon counting energy sensitive x-ray systems. A second purpose of the investigation is to evaluate the possible improvement compared to using pixel based weights. Methods: The Fourier based approach of imaging performance and detectability index d' is applied to pulse height discriminating photon counting systems. The dependency of d' on the bin weight factors is made explicit, taking into account both differences in signal and noise transfer characteristics across bins and the spatial frequency dependency of interbin correlations from reabsorbed scatter. Using a simplified model of a specific silicon detector, d' values for a high and a low frequency imaging task are determined for optimal weights and compared to pixel based weights. Results: The method successfully identifies bins where a large point spread function degrades detection of high spatial frequency targets. The method is also successful in determining how to downweigh highly correlated bins. Quantitative predictions for the simplified silicon detector model indicate that improvements in the detectability index when applying task-based weights instead of pixel based weights are small for high frequency targets, but could be in excess of 10% for low frequency tasks where scatter-induced correlation otherwise degrade detectability. Conclusions: The proposed method makes the spatial frequency dependency of complex correlation structures between bins and their effect on the system detective quantum efficiency easier to analyze and allows optimizing bin weights for given imaging tasks. A potential increase in detectability of double digit percents in silicon detector systems operated at typical CT energies (100 kVp) merits further evaluation on a real system. The method is noted to be of higher relevance for silicon detectors than for cadmium (zink) telluride detectors.

  6. Is M82 X-1 Really an Intermediate-Mass Black Hole? X-Ray Spectral and Timing Evidence

    NASA Technical Reports Server (NTRS)

    Fiorito, Ralph; Titarchuk, Lev

    2004-01-01

    Ultraluminous X-ray sources (ULXs) with apparent luminosities up to hundreds of times the Eddington luminosity for a neutron star have been discovered in external galaxies. The existence of intermediate-mass black holes has been proposed to explain these sources. We present evidence for an intermediate-mass black hole in the ULX M82 X-1 based on the spectral features and timing (quasi-periodic oscillation [QPO]) properties of the X-radiation from this source. We revisited XMM-Newton and Rossi X-Ray Timing Explorer (RXTE) data for M82 X-1 obtained in 2001 and 1997 for XMM and RXTE, respectively. We show for these observations that the source is either in transition or in a high/soft state with photon spectral indices 2.1 and 2.7, respectively. We confirm the early determination of the QPO frequency nu approx. = 55 mHz in this source by Strohmayer & Mushotzky and identify this as the low-frequency QPO for the source. We apply a new method to determine the black hole mass of M82 X-1. The method uses the index-QPO low-frequency correlation that has been recently established in Galactic black hole candidates GRS 1915+105, XTE JI550-564, 4U 1630-47, and others. Using scaling arguments and the correlation derived from the consideration of Galactic black holes, we conclude that M82 X-1 is an intermediate black hole with a mass of the order of 1000 solar mass,.

  7. Refractive microlens array for wave-front analysis in the medium to hard x-ray range.

    PubMed

    Mayo, Sheridan C; Sexton, Brett

    2004-04-15

    We report an alternative approach to x-ray wave-front analysis that uses a refractive microlens array as a Shack-Hartmann sensor. The sensor was manufactured by self-assembly and electroplating techniques and is suitable for high-resolution wave-front analysis of medium to hard x rays. We demonstrate its effectiveness at an x-ray energy of 3 keV for analysis of x-ray wave-front perturbations caused by microscopic objects. The sensor has potential advantages over other methods for x-ray phase imaging and will also be useful for the characterization of x-ray beams and optics. PMID:15119404

  8. Absolute radiant power measurement for the Au M lines of laser-plasma using a calibrated broadband soft X-ray spectrometer with flat-spectral response.

    PubMed

    Troussel, Ph; Villette, B; Emprin, B; Oudot, G; Tassin, V; Bridou, F; Delmotte, F; Krumrey, M

    2014-01-01

    CEA implemented an absolutely calibrated broadband soft X-ray spectrometer called DMX on the Omega laser facility at the Laboratory for Laser Energetics (LLE) in 1999 to measure radiant power and spectral distribution of the radiation of the Au plasma. The DMX spectrometer is composed of 20 channels covering the spectral range from 50 eV to 20 keV. The channels for energies below 1.5 keV combine a mirror and a filter with a coaxial photo-emissive detector. For the channels above 5 keV the photoemissive detector is replaced by a conductive detector. The intermediate energy channels (1.5 keV < photon energy < 5 keV) use only a filter and a coaxial detector. A further improvement of DMX consists in flat-response X-ray channels for a precise absolute measurement of the photon flux in the photon energy range from 0.1 keV to 6 keV. Such channels are equipped with a filter, a Multilayer Mirror (MLM), and a coaxial detector. We present as an example the development of channel for the gold M emission lines in the photon energy range from 2 keV to 4 keV which has been successfully used on the OMEGA laser facility. The results of the radiant power measurements with the new MLM channel and with the usual channel composed of a thin titanium filter and a coaxial detector (without mirror) are compared. All elements of the channel have been calibrated in the laboratory of the Physikalisch-Technische Bundesanstalt, Germany's National Metrology Institute, at the synchrotron radiation facility BESSY II in Berlin using dedicated well established and validated methods. PMID:24517761

  9. Absolute radiant power measurement for the Au M lines of laser-plasma using a calibrated broadband soft X-ray spectrometer with flat-spectral response

    SciTech Connect

    Troussel, Ph.; Villette, B.; Oudot, G.; Tassin, V.; Bridou, F.; Delmotte, F.; Krumrey, M.

    2014-01-15

    CEA implemented an absolutely calibrated broadband soft X-ray spectrometer called DMX on the Omega laser facility at the Laboratory for Laser Energetics (LLE) in 1999 to measure radiant power and spectral distribution of the radiation of the Au plasma. The DMX spectrometer is composed of 20 channels covering the spectral range from 50 eV to 20 keV. The channels for energies below 1.5 keV combine a mirror and a filter with a coaxial photo-emissive detector. For the channels above 5 keV the photoemissive detector is replaced by a conductive detector. The intermediate energy channels (1.5 keV < photon energy < 5 keV) use only a filter and a coaxial detector. A further improvement of DMX consists in flat-response X-ray channels for a precise absolute measurement of the photon flux in the photon energy range from 0.1 keV to 6 keV. Such channels are equipped with a filter, a Multilayer Mirror (MLM), and a coaxial detector. We present as an example the development of channel for the gold M emission lines in the photon energy range from 2 keV to 4 keV which has been successfully used on the OMEGA laser facility. The results of the radiant power measurements with the new MLM channel and with the usual channel composed of a thin titanium filter and a coaxial detector (without mirror) are compared. All elements of the channel have been calibrated in the laboratory of the Physikalisch-Technische Bundesanstalt, Germany's National Metrology Institute, at the synchrotron radiation facility BESSY II in Berlin using dedicated well established and validated methods.

  10. Computer simulations and models for the performance characteristics of spectrally equivalent X-ray beams in medical diagnostic radiology

    PubMed Central

    Okunade, Akintunde A.

    2007-01-01

    In order to achieve uniformity in radiological imaging, it is recommended that the concept of equivalence in shape (quality) and size (quantity) of clinical Xray beams should be used for carrying out the comparative evaluation of image and patient dose. When used under the same irradiation geometry, X-ray beams that are strictly or relatively equivalent in terms of shape and size will produce identical or relatively identical image quality and patient dose. Simple mathematical models and software program EQSPECT.FOR were developed for the comparative evaluation of the performance characteristics in terms of contrast (C), contrast to noise ratio (CNR) and figure-of-merit (FOM = CNR2/DOSE) for spectrally equivalent beams transmitted through filter materials referred to as conventional and k-edged. At the same value of operating potential (kVp), results show that spectrally equivalent beam transmitted through conventional filter with higher atomic number (Z-value) in comparison with that transmitted through conventional filter with lower Z-value resulted in the same value of C and FOM. However, in comparison with the spectrally equivalent beam transmitted through filter of lower Z-value, the beam through filter of higher Z-value produced higher value of CNR and DOSE at equal tube loading (mAs) and kVp. Under the condition of equivalence of spectrum, at scaled (or reduced) tube loading and same kVp, filter materials of higher Z-value can produce the same values of C, CNR, DOSE and FOM as filter materials of lower Z-value. Unlike the case of comparison of spectrally equivalent beam transmitted through one conventional filter and that through another conventional filter, it is not possible to derive simple mathematical formulations for the relative performance of spectrally equivalent beam transmitted through a given conventional filter material and that through kedge filter material. PMID:21224928

  11. Multi-Spectral Solar Telescope Array. IV - The soft X-ray and extreme ultraviolet filters

    NASA Technical Reports Server (NTRS)

    Lindblom, Joakim F.; O'Neal, Ray H.; Walker, Arthur B. C., Jr.; Powell, Forbes R.; Barbee, Troy W., Jr.; Hoover, Richard B.

    1991-01-01

    NASA's Multi-Spectral Solar Telescope Array uses various combinations of thin foil filters composed of Al, C, Te, Be, Mo, Rh, and phthalocyanine to achieve the requisite radiation-rejection characteristics. Such rejection is demanded by the presence of strong EUV radiation at longer wavelengths where the specular reflectivity of multilayer mirrors can cause 'contamination' of the image in the narrow band defined by the Bragg condition.

  12. X-ray spectral state evolution in IGR J170913624 and comparison of its heartbeat oscillation properties with those of GRS 1915+105

    SciTech Connect

    Pahari, Mayukh; Yadav, J S; Bhattacharyya, Sudip

    2014-03-10

    In this work, we study the X-ray timing and spectral evolution of the transient low-mass X-ray binary IGR J170913624 during the first 66 days of its 2011 outburst. We present results obtained from observations with two instruments, the Rossi X-ray Timing Explorer Proportional Counter Array and SWIFT X-Ray Telescope, between 2011 February 9 and 2011 April 15. Using quasi-periodic oscillation classifications, power density spectrum characteristics, time-lag behavior, and energy spectral properties, we determine source states and their transitions at different times of the outburst. During the first part of the evolution, the source followed trends that are usually observed from transient black hole X-ray binaries (BHXBs). Interestingly, a gradual transition is observed in IGR J170913624 from the low-variability soft intermediate state, commonly seen in BHXBs, to a high-variability state with regular, repetitive, and structured pulsations, seen only from GRS 1915+105 (also known as '?' class variability/'heartbeat' oscillations). We study the time evolution of the characteristic timescale, quality factor, and rms amplitude of heartbeat oscillations in IGR J170913624. We also present a detailed comparison of the timing and spectral properties of heartbeat oscillations and their evolution in IGR J170913624 and GRS 1915+105.

  13. High dynamic range active pixel sensor arrays for digital x-ray imaging using a-Si:H

    SciTech Connect

    Lai, Jackson; Nathan, Arokia; Rowlands, John

    2006-05-15

    Hydrogenated amorphous silicon (a-Si:H) active matrix flat panel imagers have gained considerable significance in large area digital imaging applications, in view of their large area readout capability. Current interests lie in a multifaceted a-Si:H array which is compatible with multiple x-ray imaging modalities. This concept entails a single detector system with sufficient dynamic range and variable signal gain. This article reports on an active pixel sensor (APS) array with high dynamic range and programable gain for multimodality x-ray imaging. Initial results have demonstrated sensitivity from subpicoampere to nanoampere photocurrent, which proves amenable for both low-dosage dynamic imaging and high input static imaging. In addition, the programable system signal gain alleviates problems such as output saturation and ensures signal readout linearity to further improve the exploitable dynamic range. Together with external amplification, this APS circuit delivers the performance needed in terms of signal gain, dynamic range, and readout rate entailed by fluoroscopic and radiographic imaging applications.

  14. Non-invasive material discrimination using spectral x-ray radiography

    SciTech Connect

    Gilbert, Andrew J.; McDonald, Benjamin S.; Robinson, Sean M.; Jarman, Ken D.; White, Tim A.; Deinert, Mark R.

    2014-04-21

    Current radiographic methods are limited in their ability to determine the presence of nuclear materials in containers or composite objects. A central problem is the inability to distinguish the attenuation pattern of high-density metals from those with a greater thickness of a less dense material. Here, we show that spectrally sensitive detectors can be used to discriminate plutonium from multiple layers of other materials using a single-view radiograph. An inverse algorithm with adaptive regularization is used. The algorithm can determine the presence of plutonium in simulated radiographs with a mass resolution per unit area of at least 0.07 g cm{sup −2}.

  15. Non-invasive material discrimination using spectral x-ray radiography

    SciTech Connect

    Gilbert, Andrew J.; McDonald, Benjamin S.; Robinson, Sean M.; Jarman, Kenneth D.; White, Timothy A.; Deinert, Mark

    2014-04-21

    Current radiographic methods are limited in their ability to determine the presence of nuclear materials in containers or composite objects. A central problem is the inability to distinguish the attenuation pattern of high-density metals from those with a larger greater thickness of a less- dense material. Here we show that spectrally sensitive detectors can be used to discriminate plutonium from multiple layers of other materials using a single-view radiograph. An inverse algorithm with adaptive regularization is used. The algorithm can determine the presence of plutonium in simulated radiographs with a mass resolution per unit area of at least 0.07 g•cm^-2.

  16. Calibration of X-ray detectors in the 8 to 115 keV energy range and their application to diagnostics on the National Ignition Facility

    SciTech Connect

    J. J. Lee, M. J. Haugh, G. LaCaille, and P. Torres

    2012-10-01

    The calibration of X-ray diagnostics is of paramount importance to the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL). National Security Technologies LLC (NSTec) fills this need by providing a wide variety of calibration and diagnostic development services in support of the ongoing research efforts at NIF. The X-ray source in the High Energy X-ray lab utilizes induced fluorescence in a variety of metal foils to produce a beam of characteristic X rays ranging from 8 to 111 keV. Presented are the methods used for calibrating a High Purity Germanium detector, which has been absolutely calibrated using radioactive check sources, compared against a silicon photodiode calibrated at Physikalisch Technische Bundesanstalt (PTB). Also included is a limited presentation of results from the recent calibration of the upgraded Filter Fluorescer X ray Spectrometer.

  17. RXTE Spectral Study of the New X-ray Transient XTE J1859+226

    NASA Astrophysics Data System (ADS)

    Focke, W. B.; Markwardt, C. B.; Swank, J. H.; Taam, R. E.

    1999-12-01

    The transient galactic black hole candidate XTE J1859+226 was discovered by the RXTE All Sky Monitor (ASM) on 1999 October 9, within a day after its outburst began. Pointed observations with RXTE began on 1999 October 10.57, and continued at a rate of about twice per day. Preliminary results of fits to PCA and HEXTE spectra for October 9--14 show that a simple absorbed powerlaw is insufficient to model the data. The fit is greatly improved by using an absorbed cutoff powerlaw with reflection. The photon index rose from 1.8 on October 9 to 3.2 on October 14. The cutoff energy started near 100 keV, dropped to 50 keV, then rose to an undetectable level between October 12.86 and October 13.11, potentially indicating a state change. We will present spectral analysis of these and later data, along with comparison of the spectral and timing properties. This work was funded by NASA.

  18. ACCOUNTING FOR CALIBRATION UNCERTAINTIES IN X-RAY ANALYSIS: EFFECTIVE AREAS IN SPECTRAL FITTING

    SciTech Connect

    Lee, Hyunsook; Kashyap, Vinay L.; Drake, Jeremy J.; Ratzlaff, Pete; Siemiginowska, Aneta E-mail: vkashyap@cfa.harvard.edu E-mail: rpete@head.cfa.harvard.edu

    2011-04-20

    While considerable advance has been made to account for statistical uncertainties in astronomical analyses, systematic instrumental uncertainties have been generally ignored. This can be crucial to a proper interpretation of analysis results because instrumental calibration uncertainty is a form of systematic uncertainty. Ignoring it can underestimate error bars and introduce bias into the fitted values of model parameters. Accounting for such uncertainties currently requires extensive case-specific simulations if using existing analysis packages. Here, we present general statistical methods that incorporate calibration uncertainties into spectral analysis of high-energy data. We first present a method based on multiple imputation that can be applied with any fitting method, but is necessarily approximate. We then describe a more exact Bayesian approach that works in conjunction with a Markov chain Monte Carlo based fitting. We explore methods for improving computational efficiency, and in particular detail a method of summarizing calibration uncertainties with a principal component analysis of samples of plausible calibration files. This method is implemented using recently codified Chandra effective area uncertainties for low-resolution spectral analysis and is verified using both simulated and actual Chandra data. Our procedure for incorporating effective area uncertainty is easily generalized to other types of calibration uncertainties.

  19. A second-generation x-ray streak camera with true large format, high dynamic range, and high reliability

    NASA Astrophysics Data System (ADS)

    Sun, Ke-Xun; Nishimura, William; Perry, Theodore; Compton, Steve

    2005-08-01

    This paper will review the specifications, test and experiment performance features of Bechtel Nevada's Phase 2 X-ray Streak Camera (P2XSC). The P2XSC was developed to meet stringent inertial confinement fusion (ICF) and high energy density (HED) science requirements for experiments at Omega laser facility at Laboratory for Laser Energetics (LLE), and National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL). The paper reports recent progress in developing a large format, high dynamic range, and high-reliability Xray streak camera at Bechtel Nevada. We have designed, built, and tested an advanced X-ray camera. Bechtel Nevada's P2XSC substantially outperforms first generation streak cameras developed over a decade ago. Recent laboratory tests of P2XSC show that the channel dynamic range reaches 6000, the resolution reaches 50 micrometers at the photocathode (6~7 pixels at the image plane) at deep ultraviolet (UV) input wavelength, and 35 micrometers (4~5 pixels) at X-ray wavelength. The image resolution varies less than 30% across the photocathode. However, the 50 mm photocathode has a usable length of approximately 34 mm due to charge coupled device (CCD) camera limitations. The total number of resolution elements is approximately 900 in both spatial and temporal directions. The P2XSC is integrated into a compact airbox enclosure compatible with the ten-inch manipulator (TIM) specifications at LLE, Omega. The system is remotely controllable. The P2XSC system has been operated in the airbox for several thousands of shots for tests at Bechtel Nevada calibration facilities in Livermore and at the LLNL Janus laser facility. High-resolution data will be shown.

  20. Absolute spectral characterization of silicon barrier diode: Application to soft X-ray fusion diagnostics at Tore Supra

    SciTech Connect

    Vezinet, D.; Mazon, D.; Malard, P.

    2013-07-14

    This paper presents an experimental protocol for absolute calibration of photo-detectors. Spectral characterization is achieved by a methodology that unlike the usual line emissions-based method, hinges on the Bremsstrahlung radiation of a Soft X-Ray (SXR) tube only. Although the proposed methodology can be applied virtually to any detector, the application presented in this paper is based on Tore Supra's SXR diagnostics, which uses Silicon Surface Barrier Diodes. The spectral response of these n-p junctions had previously been estimated on a purely empirical basis. This time, a series of second-order effects, like the spatial distribution of the source radiated power or multi-channel analyser non linearity, are taken into account to achieve accurate measurements. Consequently, a parameterised physical model is fitted to experimental results and the existence of an unexpected dead layer (at least 5 {mu}m thick) is evidenced. This contribution also echoes a more general on-going effort in favour of long-term quality of passive radiation measurements on Tokamaks.

  1. Absolute spectral characterization of silicon barrier diode: Application to soft X-ray fusion diagnostics at Tore Supra

    NASA Astrophysics Data System (ADS)

    Vezinet, D.; Mazon, D.; Malard, P.

    2013-07-01

    This paper presents an experimental protocol for absolute calibration of photo-detectors. Spectral characterization is achieved by a methodology that unlike the usual line emissions-based method, hinges on the Bremsstrahlung radiation of a Soft X-Ray (SXR) tube only. Although the proposed methodology can be applied virtually to any detector, the application presented in this paper is based on Tore Supra's SXR diagnostics, which uses Silicon Surface Barrier Diodes. The spectral response of these n-p junctions had previously been estimated on a purely empirical basis. This time, a series of second-order effects, like the spatial distribution of the source radiated power or multi-channel analyser non linearity, are taken into account to achieve accurate measurements. Consequently, a parameterised physical model is fitted to experimental results and the existence of an unexpected dead layer (at least 5 μm thick) is evidenced. This contribution also echoes a more general on-going effort in favour of long-term quality of passive radiation measurements on Tokamaks.

  2. Spectral and timing analysis of the mHz QPOs in the neutron-star low-mass X-ray binary 4U 1636-53

    NASA Astrophysics Data System (ADS)

    Lyu, Ming; Mndez, Mariano; Zhang, Guobao; Keek, L.

    2015-11-01

    We investigate the spectral and timing properties of the millihertz quasi-periodic oscillations (mHz QPOs) in neutron-star low-mass X-ray binary 4U 1636-53 using XMM-Newton and Rossi X-ray Timing Explorer (RXTE) observations. The mHz QPOs in the XMM-Newton/RXTE observations show significant frequency variation and disappear right before type I X-ray bursts. We find no significant correlation between the mHz QPO frequency and the temperature of the neutron-star surface, which is different from theoretical predictions. For the first time we observed the full lifetime of a mHz QPO lasting 19 ks. Besides, we also measure a frequency drift time-scale 15 ks, we speculate that this is the cooling time-scale of a layer deeper than the burning depth, possibly heated by the previous burst. Moreover, the analysis of all X-ray bursts in this source shows that all type I X-ray bursts associated with the mHz QPOs are short, bright and energetic, suggesting a potential connection between mHz QPOs and He-rich X-ray bursts.

  3. Spectral variation in the supergiant fast X-ray transient SAX J1818.6-1703 observed by XMM-Newton and INTEGRAL

    NASA Astrophysics Data System (ADS)

    Boon, C. M.; Bird, A. J.; Hill, A. B.; Sidoli, L.; Sguera, V.; Goossens, M. E.; Fiocchi, M.; McBride, V. A.; Drave, S. P.

    2016-03-01

    We present the results of a 30 ks XMM-Newton observation of the supergiant fast X-ray transient (SFXT) SAX J1818.6-1703 - the first in-depth soft X-ray study of this source around periastron. INTEGRAL observations shortly before and after the XMM-Newton observation show the source to be in an atypically active state. Over the course of the XMM-Newton observation, the source shows a dynamic range of ˜100 with a luminosity greater than 1 × 1035 erg s-1 for the majority of the observation. After an ˜6 ks period of low-luminosity (˜1034 erg s-1) emission, SAX J1818.6-1703 enters a phase of fast flaring activity, with flares ˜250 s long, separated by ˜2 ks. The source then enters a larger flare event of higher luminosity and ˜8 ks duration. Spectral analysis revealed evidence for a significant change in spectral shape during the observation with a photon index varying from Γ ˜ 2.5 during the initial low-luminosity emission phase, to Γ ˜ 1.9 through the fast flaring activity, and a significant change to Γ ˜ 0.3 during the main flare. The intrinsic absorbing column density throughout the observation (nH ˜ 5 × 1023 cm-2) is among the highest measured from an SFXT, and together with the XMM-Newton and INTEGRAL luminosities, consistent with the neutron star encountering an unusually dense wind environment around periastron. Although other mechanisms cannot be ruled out, we note that the onset of the brighter flares occurs at 3 × 1035erg s-1, a luminosity consistent with the threshold for the switch from a radiative-dominated to Compton cooling regime in the quasi-spherical settling accretion model.

  4. High resolution solar X-ray studies

    NASA Technical Reports Server (NTRS)

    Blake, R. L.

    1974-01-01

    Two high resolution solar X-ray payloads and their launches on Aerobee rockets with pointing system are described. The payloads included 5 to 25A X-ray spectrometers, multiaperture X-ray cameras, and command box attitude control inflight by means of a television image radioed to ground. Spatial resolution ranged from five arc minutes to ten arc seconds and spectral resolution ranged from 500 to 3000. Several laboratory tasks were completed in order to achieve the desired resolution. These included (1) development of techniques to align grid collimators, (2) studies of the spectrometric properties of crystals, (3) measurements of the absorption coefficients of various materials used in X-ray spectrometers, (4) evaluation of the performance of multiaperture cameras, and (5) development of facilities.

  5. A digital x-ray tomosynthesis coupled near infrared spectral tomography system for dual-modality breast imaging.

    PubMed

    Krishnaswamy, Venkataramanan; Michaelsen, Kelly E; Pogue, Brian W; Poplack, Steven P; Shaw, Ian; Defrietas, Ken; Brooks, Ken; Paulsen, Keith D

    2012-08-13

    A Near Infrared Spectral Tomography (NIRST) system has been developed and integrated into a commercial Digital Breast Tomosynthesis (DBT) scanner to allow structural and functional imaging of breast in vivo. The NIRST instrument uses an 8-wavelength continuous wave (CW) laser-based scanning source assembly and a 75-element silicon photodiode solid-state detector panel to produce dense spectral and spatial projection data from which spectrally constrained 3D tomographic images of tissue chromophores are produced. Integration of the optical imaging system into the DBT scanner allows direct co-registration of the optical and DBT images, while also facilitating the synergistic use of x-ray contrast as anatomical priors in optical image reconstruction. Currently, the total scan time for a combined NIRST-DBT exam is ~50s with data collection from 8 wavelengths in the optical scan requiring ~42s to complete. The system was tested in breast simulating phantoms constructed using intralipid and blood in an agarose matrix with a 3 cm x 2 cm cylindrical inclusion at 1 cm depth from the surface. Diffuse image reconstruction of total hemoglobin (HbT) concentration resulted in accurate recovery of the lateral size and position of the inclusion to within 6% and 8%, respectively. Use of DBT structural priors in the NIRST reconstruction process improved the quantitative accuracy of the HbT recovery, and led to linear changes in imaged versus actual contrast, underscoring the advantages of dual-modality optical imaging approaches. The quantitative accuracy of the system can be further improved with independent measurements of scattering properties through integration of frequency or time domain data. PMID:23038553

  6. A digital x-ray tomosynthesis coupled near infrared spectral tomography system for dual-modality breast imaging

    PubMed Central

    Krishnaswamy, Venkataramanan; Michaelsen, Kelly E.; Pogue, Brian W.; Poplack, Steven P.; Shaw, Ian; Defrietas, Ken; Brooks, Ken; Paulsen, Keith D.

    2012-01-01

    A Near Infrared Spectral Tomography (NIRST) system has been developed and integrated into a commercial Digital Breast Tomosynthesis (DBT) scanner to allow structural and functional imaging of breast in vivo. The NIRST instrument uses an 8-wavelength continuous wave (CW) laser-based scanning source assembly and a 75-element silicon photodiode solid-state detector panel to produce dense spectral and spatial projection data from which spectrally constrained 3D tomographic images of tissue chromophores are produced. Integration of the optical imaging system into the DBT scanner allows direct co-registration of the optical and DBT images, while also facilitating the synergistic use of x-ray contrast as anatomical priors in optical image reconstruction. Currently, the total scan time for a combined NIRST-DBT exam is ~50s with data collection from 8 wavelengths in the optical scan requiring ~42s to complete. The system was tested in breast simulating phantoms constructed using intralipid and blood in an agarose matrix with a 3 cm x 2 cm cylindrical inclusion at 1 cm depth from the surface. Diffuse image reconstruction of total hemoglobin (HbT) concentration resulted in accurate recovery of the lateral size and position of the inclusion to within 6% and 8%, respectively. Use of DBT structural priors in the NIRST reconstruction process improved the quantitative accuracy of the HbT recovery, and led to linear changes in imaged versus actual contrast, underscoring the advantages of dual-modality optical imaging approaches. The quantitative accuracy of the system can be further improved with independent measurements of scattering properties through integration of frequency or time domain data. PMID:23038553

  7. Evaluation of imaging properties of soft x-ray multilayer mirrors and their application to highly dispersive spectral imaging

    SciTech Connect

    Kolachevsky, N. N.; Mitropolsky, M. M.; Ragozin, E. N.; Salashchenko, N. N.; Slemzin, V. A.; Zhitnik, I. A.

    1995-05-01

    A variety of normal-incidence multilayer mirrors (MMs) intended for studies of astrophysical and laboratory soft-x-ray radiation sources have been synthesized on concave (r=1.6-2.0 m) fused silica substrates. The MMs range in resonance wavelength {lambda}0 from 4.5 to 31 nm. Their imaging capability has been evaluated from small-source imaging tests employing to a laser-plasma broadband XUV radiation source and a high-resolution XUV photographic film. The photographs testify to a subarcsecond angular resolution. For 17.5-nm MMs, a resolution of at least {approx_equal}0.32 arcseconds has been demonstrated, which is only 2.4{lambda}0/D for the MMs involved.

  8. Observations of solar X-ray bursts in the energy range 5-15 keV

    NASA Technical Reports Server (NTRS)

    Datlowe, D. W.; Hudson, H. S.; Peterson, L. E.

    1974-01-01

    Bursts of solar X-rays in the energy range 5-15 keV are associated with flares and are due to thermal emission from a hot coronal plasma. The results of the first study of a large sample of separate bursts, 197 events associated with subflares, and of a few events of importance 1 are presented. The observations were made by a proportional counter on the satellite OSO-7 from October, 1971 to June, 1972. In most cases, the temperature characterizing the X-ray spectrum rises impulsively at the onset of the burst and then declines slowly throughout the remainder of the burst. The emission measure rises exponentially with a time scale of 30-100 sec and then declines slowly on a time scale of the order of 1,000 sec. It is shown that the growth of the thermal energy in the flare plasma throughout the burst can be due to the heating of new cool material.

  9. Examinations of tRNA Range of Motion Using Simulations of Cryo-EM Microscopy and X-Ray Data

    PubMed Central

    Caulfield, Thomas R.; Devkota, Batsal; Rollins, Geoffrey C.

    2011-01-01

    We examined tRNA flexibility using a combination of steered and unbiased molecular dynamics simulations. Using Maxwell's demon algorithm, molecular dynamics was used to steer X-ray structure data toward that from an alternative state obtained from cryogenic-electron microscopy density maps. Thus, we were able to fit X-ray structures of tRNA onto cryogenic-electron microscopy density maps for hybrid states of tRNA. Additionally, we employed both Maxwell's demon molecular dynamics simulations and unbiased simulation methods to identify possible ribosome-tRNA contact areas where the ribosome may discriminate tRNAs during translation. Herein, we collected >500?ns of simulation data to assess the global range of motion for tRNAs. Biased simulations can be used to steer between known conformational stop points, while unbiased simulations allow for a general testing of conformational space previously unexplored. The unbiased molecular dynamics data describes the global conformational changes of tRNA on a sub-microsecond time scale for comparison with steered data. Additionally, the unbiased molecular dynamics data was used to identify putative contacts between tRNA and the ribosome during the accommodation step of translation. We found that the primary contact regions were H71 and H92 of the 50S subunit and ribosomal proteins L14 and L16. PMID:21716650

  10. Microwave soft x-ray microscopy for nanoscale magnetization dynamics in the 5-10 GHz frequency range.

    PubMed

    Bonetti, Stefano; Kukreja, Roopali; Chen, Zhao; Spoddig, Detlef; Ollefs, Katharina; Schöppner, Christian; Meckenstock, Ralf; Ney, Andreas; Pinto, Jude; Houanche, Richard; Frisch, Josef; Stöhr, Joachim; Dürr, Hermann A; Ohldag, Hendrik

    2015-09-01

    We present a scanning transmission x-ray microscopy setup combined with a novel microwave synchronization scheme for studying high frequency magnetization dynamics at synchrotron light sources. The sensitivity necessary to detect small changes in the magnetization on short time scales and nanometer spatial dimensions is achieved by combining the excitation mechanism with single photon counting electronics that is locked to the synchrotron operation frequency. Our instrument is capable of creating direct images of dynamical phenomena in the 5-10 GHz range, with high spatial resolution. When used together with circularly polarized x-rays, the above capabilities can be combined to study magnetic phenomena at microwave frequencies, such as ferromagnetic resonance (FMR) and spin waves. We demonstrate the capabilities of our technique by presenting phase resolved images of a ∼6 GHz nanoscale spin wave generated by a spin torque oscillator, as well as the uniform ferromagnetic precession with ∼0.1° amplitude at ∼9 GHz in a micrometer-sized cobalt strip. PMID:26429444

  11. Microwave soft x-ray microscopy for nanoscale magnetization dynamics in the 5-10 GHz frequency range

    NASA Astrophysics Data System (ADS)

    Bonetti, Stefano; Kukreja, Roopali; Chen, Zhao; Spoddig, Detlef; Ollefs, Katharina; Schöppner, Christian; Meckenstock, Ralf; Ney, Andreas; Pinto, Jude; Houanche, Richard; Frisch, Josef; Stöhr, Joachim; Dürr, Hermann A.; Ohldag, Hendrik

    2015-09-01

    We present a scanning transmission x-ray microscopy setup combined with a novel microwave synchronization scheme for studying high frequency magnetization dynamics at synchrotron light sources. The sensitivity necessary to detect small changes in the magnetization on short time scales and nanometer spatial dimensions is achieved by combining the excitation mechanism with single photon counting electronics that is locked to the synchrotron operation frequency. Our instrument is capable of creating direct images of dynamical phenomena in the 5-10 GHz range, with high spatial resolution. When used together with circularly polarized x-rays, the above capabilities can be combined to study magnetic phenomena at microwave frequencies, such as ferromagnetic resonance (FMR) and spin waves. We demonstrate the capabilities of our technique by presenting phase resolved images of a ˜6 GHz nanoscale spin wave generated by a spin torque oscillator, as well as the uniform ferromagnetic precession with ˜0.1° amplitude at ˜9 GHz in a micrometer-sized cobalt strip.

  12. A laboratory-based Laue X-ray diffraction system for enhanced imaging range and surface grain mapping

    PubMed Central

    Whitley, William; Stock, Chris; Huxley, Andrew D.

    2015-01-01

    Although CCD X-ray detectors can be faster to use, their large-area versions can be much more expensive than similarly sized photographic plate detectors. When indexing X-ray diffraction patterns, large-area detectors can prove very advantageous as they provide more spots, which makes fitting an orientation easier. On the other hand, when looking for single crystals in a polycrystalline sample, the speed of CCD detectors is more useful. A new setup is described here which overcomes some of the limitations of limited-range CCD detectors to make them more useful for indexing, whilst at the same time making it much quicker to find single crystals within a larger polycrystalline structure. This was done by combining a CCD detector with a six-axis goniometer, allowing the compilation of images from different angles into a wide-angled image. Automated scans along the sample were coupled with image processing techniques to produce grain maps, which can then be used to provide a strategy to extract single crystals from a polycrystal. PMID:26306095

  13. X-ray spectral microanalysis of composition of individual lunar regolith particles

    NASA Technical Reports Server (NTRS)

    Ilin, N. P.; Loseva, L. Y.; Senin, V. G.

    1974-01-01

    Determinations were made of the chemical compositions of selected olivine crystals, spherical particles ranging in size from 170 to 350 micrometer, spinels, and magnetic particles. The olivines contain 30 to 50 mole percent fayalite. The spherical particles of various colors are aluminosilicate glasses, significantly enriched in CaO compared with the mean composition of the regolith. The degree of coloration depends on the FeO content and also the admixtures TiO2, MnO, and Cr2O3. Compositionally, the spinel was interpreted to be chromopicotites. Magnetic particles were shown to be complex intergrowths of nickelous iron and aluminosilicates. The composition of the metallic phase of one particle (in percent) was: Fe - 86, Ni - 13.6, and Co - 0.16 in combination with plagioclase and microinclusions of ilmenite in silicate. Kamacite was determined in another intergrowth of Fe, Ni, and Co.

  14. A phenomenological model to study the energy discrimination potential of GEM detectors in the X-ray range

    NASA Astrophysics Data System (ADS)

    Causa, F.; Pacella, D.; Romano, A.; Claps, G.; Gabellieri, L.

    2015-11-01

    An empirical model is presented to study the operational characteristics of GEM detectors in the X-ray range and, in particular, its energy discrimination potential. Physical processes are modelled from a macroscopic point of view, to provide a simple but effective simulation tool. Experimental data from monochromatic and combined, two-line fluorescence sources, are used to validate the model and provide realistic estimates of the empirical parameters used in the description. The model is instrumental in understanding the role of threshold, gain and operational conditions to achieve energy-discriminating response. Appropriate choices of gas mixtures, threshold and gain will permit to best utilise this new functionality of the GEM to improve the efficiency of image detectors in applications ranging from in-situ imaging in harsh environments, such as tokamaks, to composite materials analysis and medical imaging of tissues.

  15. The complex X ray spectra of AGN

    NASA Technical Reports Server (NTRS)

    Urry, C. M.; Arnaud, Keith; Edelson, R. A.; Kruper, J. S.; Mushotzky, R. F.

    1989-01-01

    X-ray spectral surveys of large samples of Seyfert galaxies are discussed. The spectral shape in the 0.1 to 20 keV energy range is considered. Two new spectral survey are undertaken, one involving 105 Imaging Proportional Counter (IPC) observations of 75 Seyfert galaxies, the other using IPC and Monitor Proportional Counter (MPC) data from 28 observations of 23 Seyfert galaxies. The X-ray spectra of active galactic nuclei (AGN) are complex, with in most cases considerable steepening at the lowest energies. At higher energies (2 to 20 keV), the existence of a universal, canonical power law is confirmed, independent of X-ray luminosity over four orders of magnitude.

  16. The Spectral Analysis of X-Ray Binaries from the XMM-Newton Space Craft Data using SAS Software

    NASA Astrophysics Data System (ADS)

    Baki, P.; Mito, C. O.

    2009-10-01

    A spectral data analysis on a luminous object of sky-coordinates 12h52m24.28s-29d115'02.3'12.6arcsec using Science Analysis Software (SAS) is presented. The analysis, based on data acquired by the Reflection Grating Spectrometer (RGS) camera aboard the XMM-Newton Space satellite, shows that the primary constituents of the X-ray source are Fe (Iron) and O (oxygen). This suggests that the source may be a magnetized plasma in a binary system and as this magnetic field accelerates the cooling of a star, one may speculate that this may be a compact star in its last stages of a thermonuclear fusion process. Nous prsentons une analyse du spectre d'une source a rayons X situe -- en coordonnes sidrales - 12h52m24.28s - 29d115'02.312.6 arcsec. Science Analysis Software (SAS) est le programme informatique utilis pour l'analyse des donnes. Cette analyse est base sur les donnes provenant du spectromtre haute rsolution (RGS) bord du satellite spatiale XMM-Newton. Nous montrons que ladite source est principalement constitue de Fer (Fe) et d'oxygene (O). Ce rsultat suggre que la source pourrait tre un plasma magntis au sein d'un systme binaire. Et du fait que ce champ magntique acclre le refroidissement de l'toile, nous supposons que cette toile pourrait tre un objet compact en phase terminale d'un processus de fusion thermonuclaire.

  17. Optical CCD photometry and Rosat X-ray spectral analysis of the shortest period CV EI Psc (1RXS J232953.9 + 062814)

    NASA Astrophysics Data System (ADS)

    Gk, F.; Gn, G. ?kis; Aktekin, E.; Sezer, A.; Altan, M.

    2009-02-01

    We present here the optical observations of EI Psc (1RXS J232953.9 + 062814) through Turkish National Observatory (TUG) with RTT150 cm Russian-Turkish joint telescope and its X-ray observation using the ROSAT archival data. Our optical observations reveal a period of 0.0408 days (58.75 min) which is rather different from its early value of 0.046 days (66.24 min) as reported by [Schmeer, P., 2001. vsnet-alert6830, < http://www.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-alert/mgs06830.html>]. Also possible periodicities as well as any QPOs are studied without having any clear indication of it. Archival ROSAT RASS data are also analyzed for its X-ray spectra. The raw data were fitted with various spectral models and the best fit models are found to be that of Blackbody and Raymond-Smith with best fit temperatures of kT=(0.070.02)keV for blackbody model and kT=(0.130.04)keV for Raymond-Smith model while the column density fixed at 0.5410-21cm. The estimated 0.1-2.4 keV flux is found to be in the range of between logF=-13 and logF=-14ergcm-2s-1. The model dependent luminosity values were in the range of log L=29ergs-1 for Raymond-Smith model and logL=31ergs-1 for blackbody model. Using the well fitted temperature values, the mass of the primary value that is obtained by [Uemura, M., Kato, T., Ishioka, R., Yamaoka, H., Scgmeer, P., Starkey, D.R., Torii, K., Kawai, N., Urata, Y., Kohama, M., Yoshida, A., Ayani, K., Kawabata, T., Tanabe, K., Matsumoto, K., Kiyota, S., Pietz, J., Vanmunster, T., Krajci, T., Oksanen, A., Giambersio, A., 2002b. Superhump Evolution in the Ultrashort Period Dwarf Nova 1RXS J232953.9 + 062814. PASJ 54, 599-607] and the equations taken from literature, the mass accretion rate in the boundary layer is obtained to be (1.580.14)1021gs-1 for the blackbody model and (2.20.052)1019gs-1 for Raymond-Smith model. As a result of our study it seems that the system EI Psc has a very high mass accretion rate; and because of the observed soft X-ray photons and high mass accretion rates it has an optically thick boundary layer and M-type secondary star which can be a Brown Dwarf.

  18. A Multi-Epoch Timing and Spectral Study of the Ultraluminous X-Ray NGC 5408 X-1 with XMM-Newton

    NASA Technical Reports Server (NTRS)

    Dheeraj, Pasham; Strohmayer, Tod E.

    2012-01-01

    We present results of new XMM-Newton observations of the ultraluminous X-ray source (ULX) NGC 5408 X-1, one of the few ULXs to show quasi-periodic oscillations (QPOs). We detect QPOs in each of four new (approximately equal to 100 ks) pointings, expanding the range of frequencies observed from 10 to 40 mHz. We compare our results with the timing and spectral correlations seen in stellar-mass black hole systems, and find that the qualitative nature of the timing and spectral behavior of NGC 5408 X-1 is similar to systems in the steep power-law state exhibiting Type-C QPOs. However, in order for this analogy to quantitatively hold we must only be seeing the so-called saturated portion of the QPO frequency-photon index (or disk flux) relation. Assuming this to be the case, we place a lower limit on the mass of NGC 5408 X-1 of greater than or equal to 800 solar mass. Alternatively, the QPO frequency is largely independent of the spectral parameters, in which case a close analogy with the Type-C QPOs in stellar system is problematic. Measurement of the source's timing properties over a wider range of energy spectral index is needed to definitively resolve this ambiguity. We searched all the available data for both a broad Fe emission line as well as high-frequency QPO analogs (0.1- 1 Hz), but detected neither. We place upper limits on the equivalent width of any Fe emission feature in the 6-7 keV band and of the amplitude (rms) of a high-frequency QPO analog of approximately equal to 10 eV and approximately equal to 4%, respectively.

  19. A MULTI-EPOCH TIMING AND SPECTRAL STUDY OF THE ULTRALUMINOUS X-RAY NGC 5408 X-1 WITH XMM-Newton

    SciTech Connect

    Dheeraj, Pasham R.; Strohmayer, Tod E. E-mail: tod.strohmayer@nasa.gov

    2012-07-10

    We present results of new XMM-Newton observations of the ultraluminous X-ray source (ULX) NGC 5408 X-1, one of the few ULXs to show quasi-periodic oscillations (QPOs). We detect QPOs in each of four new ( Almost-Equal-To 100 ks) pointings, expanding the range of frequencies observed from 10 to 40 mHz. We compare our results with the timing and spectral correlations seen in stellar-mass black hole systems, and find that the qualitative nature of the timing and spectral behavior of NGC 5408 X-1 is similar to systems in the steep power-law state exhibiting Type-C QPOs. However, in order for this analogy to quantitatively hold we must only be seeing the so-called saturated portion of the QPO frequency-photon index (or disk flux) relation. Assuming this to be the case, we place a lower limit on the mass of NGC 5408 X-1 of {approx}> 800 M{sub Sun }. Alternatively, the QPO frequency is largely independent of the spectral parameters, in which case a close analogy with the Type-C QPOs in stellar systems is problematic. Measurement of the source's timing properties over a wider range of energy spectral index is needed to definitively resolve this ambiguity. We searched all the available data for both a broad Fe emission line as well as high-frequency QPO analogs (0.1-1 Hz), but detected neither. We place upper limits on the equivalent width of any Fe emission feature in the 6-7 keV band and of the amplitude (rms) of a high-frequency QPO analog of Almost-Equal-To 10 eV and Almost-Equal-To 4%, respectively.

  20. Timing and spectral studies of the transient X-ray pulsar GX 304-1 during an outburst

    NASA Astrophysics Data System (ADS)

    Devasia, Jincy; James, Marykutty; Paul, Biswajit; Indulekha, Kavila

    2011-10-01

    We present the timing and spectral properties of the transient X-ray pulsar GX 304-1 during its recent outburst in 2010 August, using observations carried out with the Proportional Counter Array (PCA) instrument on board the Rossi X-ray Timing Explorer (RXTE) satellite. We detected strong intensity- and energy-dependent variations in the pulse profiles during the outburst. The pulse profile showed significant evolution over the outburst. It showed complex structures consisting of a main peak with steps on both sides during the start of the outburst. On some days, a sharp dip-like feature was seen which disappeared at the end of the outburst when the profile evolved into a sinusoidal shape. At low energies, the pulse profiles appeared complex, consisting of multiple peaks and a narrow minimum. The amplitude of the second brightest peak in low energies decreased with energy, and above 12 keV the shape of the pulse profile changed to a single broad peak with a dip-like feature. The dip had energy dependence, both in phase and in width. We detected quasi-periodic oscillations (QPOs) at 0.125 Hz with a harmonic. The QPO feature had a low rms value of 2.9 per cent and it showed a positive energy dependence up to 40 keV with the rms value increasing to 9 per cent at 40 keV. The QPO frequency decreased from 0.128 to 0.108 Hz in 12 days. During most of the outburst, the 3-30 keV spectrum of GX 304-1 can be well fitted with a partial covering power-law model with a high-energy cut-off and iron fluorescent line emission. For a few of the observations carried out during the decay of the outburst, the partial covering absorption component is found to change to single-component absorption. We also found that the partial covering and high-energy cut-off parameters vary significantly with the pulse phase.

  1. SPECTRAL ANALYSIS IN ORBITAL/SUPERORBITAL PHASE SPACE AND HINTS OF SUPERORBITAL VARIABILITY IN THE HARD X-RAYS OF LS I +61°303

    SciTech Connect

    Li, Jian; Torres, Diego F.; Zhang, Shu

    2014-04-10

    We present an INTEGRAL spectral analysis in the orbital/superorbital phase space of LS I +61°303. A hard X-ray spectrum with no cutoff is observed at all orbital/superorbital phases. The hard X-ray index is found to be uncorrelated with the radio index (non-simultaneously) measured at the same orbital and superorbital phases. In particular, the absence of an X-ray spectrum softening during periods of negative radio index does not favor a simple interpretation of the radio index variations in terms of a microquasar's changes of state. We uncover hints of superorbital variability in the hard X-ray flux, in phase with the superorbital modulation in soft X-rays. An orbital phase drift of the radio peak flux and index along the superorbital period is observed in the radio data. We explore its influence on a previously reported double-peak structure of a radio orbital light curve, and present it as a plausible explanation.

  2. X-Ray Diffraction Study of Short-Range Order and Fermi Surface Effects in Cu-Au Alloys

    NASA Astrophysics Data System (ADS)

    Yamagishi, Kiyoshi; Hashimoto, Shinya; Iwasaki, Hiroshi

    1982-02-01

    Measurement with improved resolution of X-ray diffuse scattering from short-range ordered Cu-39, 53 and 59 at.%Au alloys has been carried out by photographic method using tiny single crystals. In the pattern taken with both crystal and film kept stationary, diffuse scattering maxima appear as satellite crosses accompanied by streaks at the 110, 210 and other equivalent positions. The separation between the diffuse satellites shows a composition dependence, decreasing with increasing gold content. Fermi-surface-imaging idea suggests that this decrease is attributed to a change in the < 110> diameter of the Fermi starface of the alloys. Fourier transformation of the intensities of one of the diffuse maxima gives an interatomic correlation function, which suggests the existence of an antiphase relation between the local L10 ordered regions separated by 28 .

  3. Dependence of scatter on atomic number for x rays from tungsten and molybdenum anodes in the mammographic energy range.

    PubMed

    Aus, R J; DeWerd, L A; Pearson, D W; Micka, J A; Ng, K H

    1999-07-01

    A study was done to determine the relative amounts of scatter for the following materials with atomic numbers ranging from Z=6 to Z=82: C, Al, Ti, Fe, Cu, Zn, Zr, Y, Mo, Ta, and Pb. Measurements were performed for each material on two constant potential x-ray units--one fitted with a molybdenum (Mo) anode-Mo filter and the other with a tungsten (W) anode-aluminum (Al) filter (medium filtration) at 30 kVp. Theoretical calculations were also performed for each anode to explain the scatter behavior and to aid in predicting the behavior for materials where measurements were not made. There was good agreement between the theoretical calculations and the experimental data. PMID:10435532

  4. A Soft X-Ray Spectral Episode for the Clocked Burster, GS 1826–24 as Measured by Swift and NuStar

    NASA Astrophysics Data System (ADS)

    Chenevez, J.; Galloway, D. K.; in ’t Zand, J. J. M.; Tomsick, J. A.; Barret, D.; Chakrabarty, D.; Fürst, F.; Boggs, S. E.; Christensen, F. E.; Craig, W. W.; Hailey, C. J.; Harrison, F. A.; Romano, P.; Stern, D.; Zhang, W. W.

    2016-02-01

    We report on NuSTAR and Swift observations of a soft state of the neutron star low-mass X-ray binary GS 1826–24, commonly known as the “clocked” burster. The transition to the soft state was recorded in 2014 June through an increase of the 2–20 keV source intensity measured by MAXI, simultaneous with a decrease of the 15–50 keV intensity measured by Swift/BAT. The episode lasted approximately two months, after which the source returned to its usual hard state. We analyze the broadband spectrum measured by Swift/XRT and NuSTAR and estimate the accretion rate during the soft episode to be ≈ 13% {\\dot{m}}{{Edd}}, within the range of previous observations. However, the best-fit spectral model, adopting the double Comptonization used previously, exhibits significantly softer components. We detect seven type-I X-ray bursts, all significantly weaker (and with shorter rise and decay times) than observed previously. The burst profiles and recurrence times vary significantly, ruling out the regular bursts that are typical for this source. One burst exhibited photospheric radius expansion and we estimate the source distance as (5.7+/- 0.2) {ξ }b-1/2 kpc, where ξb parameterizes the possible anisotropy of the burst emission. The observed soft state may most likely be interpreted as a change in accretion geometry at about similar bolometric luminosity as in the hard state. The different burst behavior can therefore be attributed to this change in accretion flow geometry, but the fundamental cause and process for this effect remain unclear.

  5. Spectral characteristics of 3U 1915-05, a burst source candidate. [in X-ray astronomy

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

    An X-ray burst source has been discovered near the X-ray source 3U 1915-05. The continuum spectra of both the burst source and the quiescent source 3U 1915-05 are hard, with kT for thermal bremsstrahlung models above 20 keV. The spectrum of 3U 1915-05 has a feature at 9.1 keV, which, if attributed to absorption by hydrogen and heliumlike iron, suggests the presence of a highly ionized cloud surrounding a central X-ray source.

  6. Prediction and observation of tin and silver plasmas with index of refraction greater than one in the soft x-ray range

    SciTech Connect

    Filevich, Jorge; Grava, Jonathan; Purvis, Mike; Marconi, Mario C.; Rocca, Jorge J.; Nilsen, Joseph; Dunn, James; Johnson, Walter R.

    2006-07-15

    We present the calculated prediction and the experimental confirmation that doubly ionized Ag and Sn plasmas can have an index of refraction greater than one for soft x-ray wavelengths. Interferometry experiments conducted using a capillary discharge soft x-ray laser operating at a wavelength of 46.9 nm (26.44 eV) confirm that in few times ionized laser-created plasmas of these elements the anomalous dispersion from bound electrons can dominate the free electron contribution, making the index of refraction greater than one. The results confirm that bound electrons can strongly influence the index of refraction of numerous plasmas over a broad range of soft x-ray wavelengths confirming recent observations. The understanding of index of refraction at short wavelengths will become even more essential during the next decade as x-ray free electron lasers will become available to probe a wider variety of plasmas at higher densities and shorter wavelengths.

  7. Design and performance of a versatile curved-crystal spectrometer for high-resolution spectroscopy in the tender x-ray range

    NASA Astrophysics Data System (ADS)

    Kav?i?, M.; Budnar, M.; Mhleisen, A.; Gasser, F.; itnik, M.; Bu?ar, K.; Bohinc, R.

    2012-03-01

    A complete in-vacuum curved-crystal x-ray emission spectrometer in Johansson geometry has been constructed for a 2-6 keV energy range with sub natural line-width energy resolution. The spectrometer is designed to measure x-ray emission induced by photon and charged particle impact on solid and gaseous targets. It works with a relatively large x-ray source placed inside the Rowland circle and employs position sensitive detection of diffracted x-rays. Its compact modular design enables fast and easy installation at a synchrotron or particle accelerator beamline. The paper presents main characteristics of the spectrometer and illustrates its capabilities by showing few selected experimental examples.

  8. Design and performance of a versatile curved-crystal spectrometer for high-resolution spectroscopy in the tender x-ray range

    SciTech Connect

    Kavcic, M.; Budnar, M.; Muehleisen, A.; Gasser, F.; Zitnik, M.; Bucar, K.; Bohinc, R.

    2012-03-15

    A complete in-vacuum curved-crystal x-ray emission spectrometer in Johansson geometry has been constructed for a 2-6 keV energy range with sub natural line-width energy resolution. The spectrometer is designed to measure x-ray emission induced by photon and charged particle impact on solid and gaseous targets. It works with a relatively large x-ray source placed inside the Rowland circle and employs position sensitive detection of diffracted x-rays. Its compact modular design enables fast and easy installation at a synchrotron or particle accelerator beamline. The paper presents main characteristics of the spectrometer and illustrates its capabilities by showing few selected experimental examples.

  9. Atomic Data in X-Ray Astrophysics

    NASA Technical Reports Server (NTRS)

    Brickhouse, N. S.

    2000-01-01

    With the launches of the Chandra X-ray Observatory (CXO) and the X-ray Multimirror Mission (XMM) and the upcoming launch of the Japanese mission ASTRO-E, high resolution X-ray spectroscopy of cosmic sources has begun. Early, deep observations of three stellar coronal sources will provide not only invaluable calibration data, but will also give us benchmarks for the atomic data under collisional equilibrium conditions. Analysis of the Chandra X-ray Observatory data, and data from other telescopes taken simultaneously, for these stars is ongoing as part of the Emission Line Project. Goals of the Emission Line Project are: (1) to determine and verify accurate and robust diagnostics and (2) to identify and prioritize issues in fundamental spectroscopy which will require further theoretical and/or laboratory work. The Astrophysical Plasma Emission Database will be described in some detail, as it is introducing standardization and flexibility into X-ray spectral modeling. Spectral models of X-ray astrophysical plasmas can be generally classified as dominated by either collisional ionization or by X-ray photoionization. While the atomic data needs for spectral models under these two types of ionization are significantly different, there axe overlapping data needs, as I will describe. Early results from the Emission Line Project benchmarks are providing an invaluable starting place, but continuing work to improve the accuracy and completeness of atomic data is needed. Additionally, we consider the possibility that some sources will require that both collisional ionization and photoionization be taken into account, or that time-dependent ionization be considered. Thus plasma spectral models of general use need to be computed over a wide range of physical conditions.

  10. GRBs and Lobster Eye X-Ray Telescopes

    NASA Astrophysics Data System (ADS)

    Hudec, R.; Pina, L.; Marsikova, V.; Inneman, A.

    2013-07-01

    A large majority of GRBs exhibit X-ray emission. In addition, a dedicated separate group of GRB, the XRFs, exists which emission dominates in the X-ray spectral range. And the third group of GRB related objects (yet hypothetical) are the group of off-axis observed GRBs (orphan afterglows). These facts justify the consideration of an independent experiment for monitoring, detection and analyses of GRBs and others fast X-ray transients in X-rays. We will present and discuss such experiment based on wide-field X-ray telescopes of Lobster Eye type. We show that the wide field and fine sensitivity of Lobster Eye X-ray All-Sky Monitor make such instruments important tools in study of GRBs.

  11. Quasar x-ray spectra revisited

    NASA Technical Reports Server (NTRS)

    Shastri, P.; Wilkes, B. J.; Elvis, M.; Mcdowell, J.

    1992-01-01

    A sample of 45 quasars observed by the Imaging Proportional Counter (IPC) on the Einstein satellite is used to re-examine the relationship between the soft (0.2-3.5 keV) X-ray energy index and radio-loudness. We found the following: (1) the tendency for radio-loud quasars to have systematically flatter X-ray slopes than radio-quiet quasars (RQQ's) is confirmed with the soft X-ray excess having negligible effect; (2) there is a tendency for the flatness of the X-ray slope to correlate with radio core-dominance for radio-loud quasars, suggesting that a component of the X-ray emission is relativistically beamed; (3) for the RQQ's the soft X-ray slopes, with a mean of approximately 1.0, are consistent with the slopes found at higher energies (2-10 keV) although steeper than those observed for Seyfert 1 galaxies (also 2-10 keV) where the reflection model gives a good fit to the data; (4) the correlation of FeII emission line strength with X-ray energy index is confirmed for radio-quiet quasars using a subset of 18 quasars. The radio-loud quasars show no evidence for a correlation. This relation suggests a connection between the ionizing continuum and the line emission from the broad emission line region (BELR) of radio-quiet quasars, but in the opposite sense to that predicted by current photoionization models; and (5) the correlations of X-ray slope with radio core dominance and FeII equivalent width within the radio-loud and radio-quiet sub-classes respectively imply that the observed wide range of X-ray spectral slopes is real rather than due to the large measuring uncertainties for individual objects.

  12. High resolution in the soft x-ray range from a toroidal grating monochromator

    SciTech Connect

    Reich, T.; Hussain, Z.; Moler, E.; Blackwell, M.; Kaindl, G. ); Shirley, D.A. ); Howells, M.R. )

    1993-09-01

    A resolving power, [ital E]/[Delta][ital E], of [ge]13 000 has been achieved with the modified 6 m/160[degree] toroidal grating monochromator (TGM) installed on Beam Line 8-1 at the Stanford Synchrotron Radiation Laboratory. The resolving power of the TGM was increased by replacing the entrance and exit slits with high-precision slits, masking the horizontal part (short radius) of the grating, and improving the TGM scanning mechanisms. To determine the performance of the monochromator, we measured the dependences of resolution and photon flux on the entrance- and exit-slit widths, the exit-slit position, and the masking of the grating. The monochromator resolution in the energy range of 25--65 eV was derived from photoionization measurements of extremely narrow core-excitation resonances in He and Ne. With 10-[mu]m vertical entrance- and exit-slit widths and 32% mask opening of the grating, the monochromator has a resolution (full-width at half maximum) of 5.0[plus minus]0.7 meV at a photon energy of 64.5 eV and a flux of 2[times]10[sup 7] photons/s/100 mA. The results suggest a simple procedure for converting a TGM with moderate resolution into a high-resolution monochromator with a moderate reduction in photon flux due to masking the grating, beyond the reduction attributable to the slit widths.

  13. Testing MOND over a wide acceleration range in x-ray ellipticals.

    PubMed

    Milgrom, Mordehai

    2012-09-28

    The gravitational fields of two isolated ellipticals, NGC 720 and NGC 1521, have been recently measured to very large galactic radii (~100 and ~200 kpc), assuming hydrostatic balance of the hot gas enshrouding them. They afford, for the first time to my knowledge, testing modified Newtonian dynamics (MOND) in ellipticals with force and quality that, arguably, approach those of rotation-curve tests in disk galaxies. In the context of MOND, it is noteworthy that the measured accelerations span a wide range, from more than 10a(0) to about 0.1a(0), unprecedented in individual ellipticals. I find that MOND predicts correctly the measured dynamical mass runs (apart from a possible minor tension in the inner few kpc of NGC 720, which might be due to departure from hydrostatic equilibrium): The predicted mass discrepancy increases outward from none near the center, to ~10 at the outermost radii. The implications for the MOND-versus-dark-matter controversy go far beyond the simple fact of two more galaxies conforming to MOND. PMID:23030078

  14. Application of the Monte Carlo codes PENELOPE and MCNP5 to unfold X-ray spectra in the diagnostic energy range

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    Obtaining primary X-ray spectra is a complex task, mainly due to the high fluence of X-rays. In order to avoid the pile up effect in the detector, an indirect method based on the Compton scattering interactions in a low density rod material can be successfully applied in the diagnostic energy range. In this work, the Monte Carlo codes PENELOPE and MCNP5 have been used to simulate the indirect method based on a simplified Compton spectrometry technique. Both models include the X-ray focus, a poly(mehtylmethacrylate) (PMMA) rod and an HPGe detector. Because the probability that primary photons scattered in the PMMA will be emitted towards the detector is small, it is necessary to consider appropriate values for cut-offs and other simulation parameters. With these models, a response function can be determined, relating the response of the detector to the primary X-ray spectrum. This function can be normally expressed as a matrix, which can be calculated by simulating the response detector to several monochromatic X-ray beams. The main goal of this work is to test the capability of the Monte Carlo codes PENELOPE and MCNP5, together with unfolding methods to estimate the primary spectrum when the response matrix and the response of the detector for a given conditions are known. The reliability of unfolded X-ray spectra is studied by comparing them with theoretical spectra obtained from the IPEM 78 catalog and calculating the Root Mean Squared (RMS) and Quality parameters.

  15. Extended dynamic range of ultra-high speed gated microchannel plate for x-ray framing camera

    NASA Astrophysics Data System (ADS)

    Pan, Jingsheng; Lv, Jingwen; Cao, Zhurong; Liu, Shenye; Liu, Shulin; Li, Yanhong

    2009-07-01

    X-ray framing cameras (XFC) based on an ultra-high speed gated microchannel plate (MCP) as a routine diagnostic in laser-driven Inertial Confinement Fusion (ICF) experiment have deployed on domestic facility for several years, typically, these XFC devices used a normal MCP with 500?m thick and 12?m pore size, and achieved an optical temporal gate leas than 100 picoseconds, but which are vulnerable to suffer a time broadened temporal response when encounter heavy expose, due to the limited dynamic range of the normal MCP. We developed a 56mm format MCP with 250?m thickness and 6?m pore diameter, which objective is to promote the optical temporal gate and dynamic range for the upgrade XFC, this MCP is fabricated by a special designed low resistance glass, the reduced thickness, small pore size and increased gain linearity, offered which with ultra-fast temporal response and extended dynamic range characters. In this paper, we review the mechanisms that limiting the temporal response and gain linearity of this ultra-high speed gated MCP applied to XFC, and describe the design principle and development work of this ultra-fast temporal response, extended dynamic range and larger format MCP, this MCP will assemble to the upgrade XFC which is designed by CAEP and is currently in the final design stages.

  16. The contribution of AGNs to the X-ray background.

    NASA Astrophysics Data System (ADS)

    Comastri, A.; Setti, G.; Zamorani, G.; Hasinger, G.

    1995-04-01

    We report the results of a detailed analysis of the contribution of various classes of AGNs (Seyfert galaxies and quasars) to the extragalactic X-ray background (XRB). The model is based on the unification schemes of AGNs, on their related X-ray spectral properties in the light of recent observational results and on the X-ray luminosity function derived by Boyle et al. (1993). The integrated emission from AGNs, when folded with an appropriate cosmological evolution law, can provide a good fit to the XRB over a wide energy range, from several to ~100keV, while it contributes only about 74% of the ROSAT soft XRB. The baseline model predictions have been checked against all available observational constraints from both hard and soft X-ray surveys (counts, redshift distributions and average X-ray source spectral properties).

  17. Explorer Program: X-ray Timing Explorer

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This booklet describes the X-ray Timing Explorer (XTE), one in a series of Explorer missions administered by the National Aeronautics and Space Administration's (NASA) Office of Space Science and managed by the NASA Goddard Space Flight Center (GSFC). The X-ray astronomy observatory is scheduled for launch into low-Earth orbit by Delta 2 expendable launch vehicle in late summer of 1995. The mission is expected to operate for at least 2 years and will carry out in-depth timing and spectral studies of the X-ray sources in the 2 to 200 kilo-electron Volt (keV) range. XTE is intended to study the temporal and broad-band spectral phenomena associated with stellar and galactic systems containing compact objects, including neutron stars, white dwarfs, and black holes.

  18. Combined microstructure x-ray optics

    SciTech Connect

    Barbee, T.W. Jr.

    1989-02-01

    Multilayers are man-made microstructures which vary in depth and are now of sufficient quality to be used as x-ray, soft x-ray and extreme ultraviolet optics. Gratings are man-made in plane microstructures which have been used as optic elements for most of this century. Joining of these two optical microstructures to form combined microstructure optical microstructures to form combined microstructure optical elements has the potential for greatly enhancing both the throughput and the resolution attainable in these spectral ranges. The characteristics of these new optic elements will be presented and compared to experiment with emphasis on the unique properties of these combined microstructures. These results reported are general in nature and not limited to the soft x-ray or extreme ultraviolet spectral domains and also apply to neutrons. 19 refs., 7 figs., 4 tabs.

  19. Exploring the Full Range of Properties of Quasar Spectral Distributions

    NASA Technical Reports Server (NTRS)

    Wilkes, B.

    1998-01-01

    The aim of this work is to support our ISO, far-infrared (IR) observing program of quasars and active galaxies. We have obtained, as far as possible, complete spectral energy distributions (radio-X-ray) of the ISO sample in order to fully delineate the continuum shapes and to allow detailed modelling of that continuum. This includes: ground-based optical, near-IR and mm data, the spectral ranges closest to the ISO data, within 1-2 years of the ISO observations themselves. ISO was launched in Nov 1995 and is currently observing routinely. It has an estimated lifetime is 2 years. All near-IR and optical imaging and spectroscopy are now in hand and in the process of being reduced, mm data collection and proposal writing continues.

  20. Ionization-Gasdynamics Modelling, and X-ray Spectral Calculations, of Wind-Bubbles around Massive Stars

    NASA Astrophysics Data System (ADS)

    Dwarkadas, V.; Rosenberg, D.

    2014-07-01

    Using a code that employs a self-consistent method for computing the effects of photo-ionization on circumstellar gas dynamics, we model the formation of wind-driven nebulae around massive stars. Our algorithm incorporates a simplified model of the photo-ionization source, computes the fractional ionization of hydrogen due to the photo-ionizing flux and recombination, and determines self-consistently the energy balance due to ionization, photo-heating and radiative cooling. We take into account changes in stellar properties and mass-loss over the star's evolution. Our multi-dimensional simulations clearly reveal the presence of strong ionization front instabilities, similar to those seen in galactic ionization fronts. Using various X-ray emission models, we compute the X-ray flux and spectra from our wind bubble models, taking the absorption of the X-rays by the ionized bubble into account. Our simulated X-ray spectra compare reasonably well with observed spectra of Wolf-Rayet bubbles. They suggest that X-ray nebulae around massive stars may not be easily detectable, consistent with observations.

  1. LONG-TERM X-RAY MONITORING OF LS I +61{sup 0}303: ANALYSIS OF SPECTRAL VARIABILITY AND FLARES

    SciTech Connect

    Li Jian; Zhang Shu; Chen Yupeng; Wang Jianmin; Torres, Diego F.; Hadasch, Daniela; Rea, Nanda; Ray, Paul S.; Kretschmar, Peter

    2011-06-01

    We report on the full analysis of a Rossi X-ray Timing Explorer Proportional Counter Array monitoring of the {gamma}-ray binary system LS I +61{sup 0}303. The data set covers 42 contiguous cycles of the system orbital motion. Analyzing this X-ray monitoring data set, the largest to date for this source, we report on the variability of the orbital profile and the spectral distribution, and provide strong evidence for an anti-correlation between flux and spectral index (the higher the flux, the harder the spectral index). Furthermore, we present the analysis of two newly discovered kilosecond-timescale flares, which present significant variability also on shorter timescales and tend to occur at orbital phases between 0.6 and 0.9. However, a detailed timing analysis of the flares does not show any coherent or quasi-coherent (QPO) structure in their power spectra. We also investigated the possible appearance of the radio super-orbital modulation at X-ray energies, but we could not unambiguously detect such modulation in the system flux history nor in the evolution of its orbital modulation fraction.

  2. X-ray variability with spectral state transitions in NS-LMXBs observed with MAXI/GSC and Swift/BAT

    NASA Astrophysics Data System (ADS)

    Asai, Kazumi; Mihara, Tatehiro; Matsuoka, Masaru; Sugizaki, Mutsumi

    2015-10-01

    X-ray variabilities with spectral state transitions in bright low-mass X-ray binaries containing a neutron star are investigated by using the one-day bin light curves of MAXI/GSC (Gas Slit Camera) and Swift/BAT (Burst Alert Telescope). Four sources (4U 1636-536, 4U 1705-44, 4U 1608-52, and GS 1826-238) exhibited small-amplitude X-ray variabilities with spectral state transitions. Such "mini-outbursts" were characterized by smaller amplitudes (several times) and shorter duration (less than several tens of days) than those of "normal outbursts." A theoretical model of disk instability by Mineshige and Osaki (PASJ, 37, 1, 1985) predicts both large-amplitude outbursts and small-amplitude variabilities. We interpret the normal outbursts as the former prediction of this model, and the mini-outbursts as the latter. Here, we can also call the mini-outburst a "purr-type outburst" referring to the theoretical work. We suggest that similar variabilities lasting for several tens of days without spectral state transitions, which are often observed in the hard state, may be repeats of mini-outbursts.

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

    SciTech Connect

    Baskaran, R.; Selvakumaran, T. S.

    2008-02-15

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

  4. ON THE CONSTANCY OF THE PHOTON INDEX OF X-RAY SPECTRA OF 4U 1728-34 THROUGH ALL SPECTRAL STATES

    SciTech Connect

    Seifina, Elena; Titarchuk, Lev E-mail: titarchuk@fe.infn.it

    2011-09-10

    We present an analysis of the spectral properties observed in X-rays from neutron star X-ray binary 4U 1728-34 during transitions between the low- and high-luminosity states when the electron temperature kT{sub e} of the Compton cloud monotonically decreases from 15 to 2.5 keV. We analyze the transition episodes from this source observed with Beppo SAX and RXTE satellites. We find that the X-ray broadband energy spectra of 4U 1728-34 during all spectral states can be modeled by a combination of a thermal (blackbody-like) component, a Comptonized component (which we herein denote as COMPTB), and a Gaussian component. Spectral analysis using this model provides evidence that the photon power-law index {Gamma} is almost constant ({Gamma} = 1.99 {+-} 0.02) when kT{sub e} changes from 15 to 2.5 keV during these spectral transitions. We explain this quasi-stability of the index {Gamma} by the model in which the spectrum is dominated by the strong thermal Comptonized component formed in the transition layer (TL) between the accretion disk and neutron star surface. The index quasi-stability takes place when the energy release in the TL is much higher than the flux coming to the TL from the accretion disk. Moreover, this index stability effect now established for 4U 1728-34 during spectral evolution of the source was previously suggested for a number of other neutron binaries. This intrinsic property of the neutron star is fundamentally different from that in black hole binary sources for which the index monotonically increases during spectral transition from the low state to the high state and saturates at high values of the mass accretion rate.

  5. Measurement of the x-ray mass attenuation coefficients of gold in the 38-50-keV energy range

    SciTech Connect

    Islam, M T; Rae, N A; Glover, J L; Barnea, Z; de Jonge, M D; Tran, C Q; Wang, J; Chantler, C T

    2010-11-12

    We used synchrotron x rays to measure the x-ray mass attenuation coefficients of gold at nine energies from 38 to 50 keV with accuracies of 0.1%. Our results are much more accurate than previous measurements in this energy range. A comparison of our measurements with calculated mass attenuation coefficients shows that our measurements fall almost exactly midway between the XCOM and FFAST calculated theoretical values, which differ from one another in this energy region by about 4%, even though the range includes no absorption edge. The consistency and accuracy of these measurements open the way to investigations of the x-ray attenuation in the region of the L absorption edge of gold.

  6. Time-dependent, x-ray spectral unfolds and brightness temperatures for intense Li + ion beam-driven hohlraums

    NASA Astrophysics Data System (ADS)

    Fehl, D. L.; Chandler, G. A.; Biggs, F.; Dukart, R. J.; Moats, A. R.; Leeper, R. J.

    1997-01-01

    X-ray-producing hohlraums are being studied as indirect drives for inertial confinement fusion targets. In a 1994 target series on the PBFAII accelerator, cylindrical hohlraum targets were heated by an intense Li+ ion beam and viewed by an array of 13 time-resolved, filtered x-ray detectors (XRDs). The unfold operator (UFO) code and its suite of auxiliary functions were used extensively in obtaining time-resolved x-ray spectra and radiation temperatures from this diagnostic. The UFO was also used to obtain fitted response functions from calibration data, to simulate data from blackbody x-ray spectra of interest, to determine the suitability of various unfolding parameters (e.g., energy domain, energy partition, smoothing conditions, and basis functions), to interpolate the XRD signal traces, and to unfold experimental data. The simulation capabilities of the code were useful in understanding an anomalous feature in the unfolded spectra at low photon energies (⩽100 eV). Uncertainties in the differential and energy-integrated unfolded spectra were estimated from uncertainties in the data. The time-history of the radiation temperature agreed well with independent calculations of the wall temperature in the hohlraum.

  7. [Investigation of the columnar carbon-scatterer length for X-ray spectral measurement on 320-slice computed tomography].

    PubMed

    Kasai, Yohei; Nishihara, Sadamitsu; Yuasa, Masao; Kanoshige, Toshiya; Matsuura, Takaaki

    2015-05-01

    A short length scatterer is adopted to measure the X-ray spectrum of computed tomography (CT) equipment with a wide irradiation field in the body axis direction. The purpose of this study is to compare X-ray spectra measured using different length scatterers and determine the most appropriate length for the scatterer. 320-slice CT equipment (Aquilion ONE) was used in this study. Circular carbonrods (3 cm diameter) with five different lengths (1-16 cm) were used as scatterers. The effect of the beam hardening phenomenon from different length carbon rods was evaluated according to the effective energy. The measurement accuracy for photon information was also evaluated based on the photon count corresponding to the characteristic X-ray. As a result, the beam hardening effect was scarcely observed when the 1 cm long scatterer was used, and the number of the photons measured for the characteristic X-ray was the most. Therefore, it was concluded that the 1 cm long circular carbon rod scatterer was the most suitable. PMID:25994395

  8. Spectral and Timing Properties of the Black Hole X-Ray Binary H1743-322 in the Low/Hard State Studied with Suzaku

    NASA Astrophysics Data System (ADS)

    Shidatsu, M.; Ueda, Y.; Yamada, S.; Done, C.; Hori, T.; Yamaoka, K.; Kubota, A.; Nagayama, T.; Moritani, Y.

    2014-07-01

    We report on the results from Suzaku observations of the Galactic black hole X-ray binary H1743-322 in the low/hard state during its outburst in 2012 October. We appropriately take into account the effects of dust scattering to accurately analyze the X-ray spectra. The time-averaged spectra in the 1-200 keV band are dominated by a hard power-law component of a photon index of ?1.6 with a high-energy cutoff at ?60 keV, which is well described with the Comptonization of the disk emission by the hot corona. We estimate the inner disk radius from the multi-color disk component, and find that it is 1.3-2.3 times larger than the radius in the high/soft state. This suggests that the standard disk was not extended to the innermost stable circular orbit. A reflection component from the disk is detected with R = ?/2? ? 0.6 (? is the solid angle). We also successfully estimate the stable disk component independent of the time-averaged spectral modeling by analyzing short-term spectral variability on a ~1 s timescale. A weak low-frequency quasi-periodic oscillation at 0.1-0.2 Hz is detected, whose frequency is found to correlate with the X-ray luminosity and photon index. This result may be explained by the evolution of the disk truncation radius.

  9. Spectral and timing properties of the black hole X-ray binary H1743–322 in the low/hard state studied with Suzaku

    SciTech Connect

    Shidatsu, M.; Ueda, Y.; Hori, T.; Yamada, S.; Done, C.; Yamaoka, K.; Kubota, A.; Nagayama, T.; Moritani, Y.

    2014-07-10

    We report on the results from Suzaku observations of the Galactic black hole X-ray binary H1743–322 in the low/hard state during its outburst in 2012 October. We appropriately take into account the effects of dust scattering to accurately analyze the X-ray spectra. The time-averaged spectra in the 1-200 keV band are dominated by a hard power-law component of a photon index of ≈1.6 with a high-energy cutoff at ≈60 keV, which is well described with the Comptonization of the disk emission by the hot corona. We estimate the inner disk radius from the multi-color disk component, and find that it is 1.3-2.3 times larger than the radius in the high/soft state. This suggests that the standard disk was not extended to the innermost stable circular orbit. A reflection component from the disk is detected with R = Ω/2π ≈ 0.6 (Ω is the solid angle). We also successfully estimate the stable disk component independent of the time-averaged spectral modeling by analyzing short-term spectral variability on a ∼1 s timescale. A weak low-frequency quasi-periodic oscillation at 0.1-0.2 Hz is detected, whose frequency is found to correlate with the X-ray luminosity and photon index. This result may be explained by the evolution of the disk truncation radius.

  10. X-Ray Spectral Residuals in NGC 5408 X-1: Diffuse Emission from Star Formation, or the Signature of a Super-Eddington Wind?

    NASA Astrophysics Data System (ADS)

    Sutton, Andrew D.; Roberts, Timothy P.; Middleton, Matthew J.

    2015-11-01

    If ultraluminous X-ray sources (ULXs) are powered by accretion onto stellar remnant black holes, then many must be accreting at super-Eddington rates. It is predicted that such high accretion rates should give rise to massive, radiatively driven winds. However, observational evidence of a wind, in the form of absorption or emission features, has remained elusive. As such, the reported detection of X-ray spectral residuals in XMM-Newton spectra of NGC 5408 X-1, which could be related to absorption in a wind is potentially very exciting. However, it has previously been assumed by several authors that these features simply originate from background diffuse plasma emission related to star formation in the ULXs host galaxy. In this work we utilize the spatial resolving power of Chandra to test whether we can rule out this latter interpretation. We demonstrate that the majority of the luminosity in these spectral features is emitted from a highly localized region close to the ULX, and appears point-like even with Chandra. It is therefore highly likely that the spectral features are associated with the ULX itself, and little of the flux in this spectral component originates from spatially extended emission in the host galaxy. This may be consistent with the suggestion of absorption in an optically thin phase of a super-Eddington wind. Alternatively, we could be seeing emission from collisionally ionized material close to the black hole, but critically this would be difficult to reconcile with models where the source inclination largely determines the observed X-ray spectral and timing properties.

  11. SAXES, a high resolution spectrometer for resonant x-ray emission in the 400-1600 eV energy range

    SciTech Connect

    Ghiringhelli, G.; Piazzalunga, A.; Dallera, C.; Trezzi, G.; Braicovich, L.; Schmitt, T.; Strocov, V. N.; Betemps, R.; Patthey, L.; Wang, X.; Grioni, M.

    2006-11-15

    We present a 5 m long spectrometer for soft x rays to be used at a synchrotron radiation beamline for resonant x-ray emission spectroscopy and resonant inelastic x-ray scattering in the 400-1600 eV energy range. It is based on a variable line spacing spherical grating (average groove density of 3200 mm{sup -1}, R=58.55 m) and a charge coupled device two dimensional detector. With an x-ray spot on the sample of 10 {mu}m, the targeted resolving power is higher than 10 000 at all energies below 1100 eV and better than 7000 at 1500 eV. The off-line tests made with Al and Mg K{alpha}{sub 1,2} fluorescence emissions indicate that the spectrometer can actually work at 12 000 and 17 000 resolving power at the L{sub 3} edges of Cu (930 eV) and of Ti (470 eV), respectively. SAXES (superadvanced x-ray emission spectrometer) is mounted on a rotating platform allowing to vary the scattering angle from 25 degree sign to 130 degree sign . The spectrometer will be operational at the ADRESS (advanced resonant spectroscopies) beamline of the Swiss Light Source from 2007.

  12. Absolute Calibration of Kodak Biomax-MS Film Response to X Rays in the 1.5- to 8-keV Energy Range

    SciTech Connect

    Marshall, F.J.; Knauer, J.P.; Anderson, D.; Schmitt, B.L.

    2006-09-28

    The absolute response of Kodak Biomax-MS film to x rays in the range from 1.5- to 8-keV has been measured using a laboratory e-beam generated x-ray source. The measurements were taken at specific line energies by using Bragg diffraction to produce monochromatic beams of x rays. Multiple exposures were taken on Biomax MS film up to levels exceeding optical densities of 2 as measured by a microdensitometer. The absolute beam intensity for each exposure was measured with a Si(Li) detector. Additional response measurements were taken with Kodak direct exposure film (DEF) so as to compare the results of this technique to previously published calibrations.

  13. Reduction in the intensity of solar X-ray emission in the 2- to 15-keV photon energy range and heating of the solar corona

    SciTech Connect

    Mirzoeva, I. K.

    2013-04-15

    The time profiles of the energy spectra of low-intensity flares and the structure of the thermal background of the soft X-ray component of solar corona emission over the period of January-February, 2003, are investigated using the data of the RHESSI project. A reduction in the intensity of X-ray emission of the solar flares and the corona thermal background in the 2- to 15-keV photon energy range is revealed. The RHESSI data are compared with the data from the Interball-Geotail project. A new mechanism of solar corona heating is proposed on the basis of the results obtained.

  14. Empirical and semi-empirical interpolation of L X-ray fluorescence parameters for elements in the atomic range 50?Z?92

    NASA Astrophysics Data System (ADS)

    Aylikci, V.; Kahoul, A.; Kup Aylikci, N.; Tira?o?lu, E.; Karahan, ?. H.; Abassi, A.; Dogan, M.

    2015-01-01

    In this study, interpolations (empirical and semi-empirical) of L sub-shell fluorescence yield and L shell Coster-Kronig transition probability values and the measured L X-ray production cross-sections, intensity ratios and L sub-shell fluorescence yield values of elements have been performed in the range of 50?Z?92. In this experimental setup, two sources (50 mCi 55Fe and 50 mCi 241Am) were used. L X-rays emitted by samples were counted by an Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV.

  15. X-ray optics of gold nanoparticles.

    PubMed

    Letfullin, Renat R; Rice, Colin E W; George, Thomas F

    2014-11-01

    Gold nanoparticles have been investigated as contrast agents for traditional x-ray medical procedures, utilizing the strong absorption characteristics of the nanoparticles to enhance the contrast of the detected x-ray image. Here we use the Kramers-Kronig relation for complex atomic scattering factors to find the real and imaginary parts of the index of refraction for the medium composed of single-element materials or compounds in the x-ray range of the spectrum. These complex index of refraction values are then plugged into a Lorenz-Mie theory to calculate the absorption efficiency of various size gold nanoparticles for photon energies in the 1-100 keV range. Since the output from most medical diagnostic x-ray devices follows a wide and filtered spectrum of photon energies, we introduce and compute the effective intensity-absorption-efficiency values for gold nanoparticles of radii varying from 5 to 50 nm, where we use the TASMIP model to integrate over all spectral energies generated by typical tungsten anode x-ray tubes with kilovolt potentials ranging from 50 to 150 kVp. PMID:25402878

  16. Synthesis, spectral, X-ray diffraction and thermal studies of new ZnII-pyrazine coordination polymers

    NASA Astrophysics Data System (ADS)

    Marandi, Farzin

    2014-02-01

    Two new zinc(II) coordination polymers with a ?-diketone and N-donor ancillary ligands, [Zn(pyz)(ttfa)2]n (1) and [Zn(pyz)(btfa)2]n (2), (Httfa = 2-thenoyltrifluoroacetone, Hbtfa = benzoyltrifluoroacetone and pyz = pyrazine), have been prepared and characterized by elemental analysis, IR, 1H NMR and 13C NMR spectroscopy, and studied by thermal gravimetric analysis as well as single crystal X-ray diffraction. The crystal and molecular structures of 1 and 2 have been solved by X-ray diffraction and they turned out to be one-dimensional polymers with linear dispositions of the metal atoms. These one-dimensional polymers are further connected to form a 3D supramolecular network by CH⋯? (only in 1), CH⋯F, ?-? and interesting H⋯H (only in 2) interactions.

  17. The 2006-2007 Active Phase Of Anomalous X-Ray Pulsar 4U 0142+61: Radiative and Timing Changes, Bursts, and Burst Spectral Features

    NASA Technical Reports Server (NTRS)

    Gavril, Fotis P.; Dib, Rim; Kaspi, Victoria M.

    2009-01-01

    After at least 6 years of quiescence, Anomalous X-ray Pulsar (AXP) 4U 0142+61 entered an active phase in 2006 March that lasted several months and included six X-ray bursts as well as many changes in the persistent X-ray emission. The bursts, the first seen from this AXP in >11 years of Rossi X-ray Timing Explorer monitoring, all occurred in the interval between 2006 April 6 and 2007 February 7. The burst durations ranged from 8-3x10(exp 3)s. The first five burst spectra are well modeled by blackbodies, with temperatures kT approx. 2 - 6 keV. However, the sixth burst had a complicated spectrum that is well characterized by a blackbody plus three emission features whose amplitude varied throughout the burst. The most prominent feature was at 14.0 keV. Upon entry into the active phase the pulsar showed a significant change in pulse morphology and a likely timing glitch. The glitch had a total frequency jump of (1.9+/-0.4)x10(exp -7) Hz, which recovered with a decay time of 17+/-2 days by more than the initial jump, implying a net spin-down of the pulsar. We discuss these events in the context of the magnetar model.

  18. Simultaneous imaging and spectral observations in microwaves and hard X-rays of the impulsive phase of a solar limb flare

    NASA Technical Reports Server (NTRS)

    Schmahl, E. J.; Kundu, M. R.; Dennis, B. R.

    1986-01-01

    Observations of the impulsive phase of a solar flare at microwave wavelengths and in hard X-rays are used to deduce the strength of the magnetic field and the number of energetic electrons producing the burst. The microwave observations, using the VLA at 6 cm, had spatial resolution of 8 x 8 arcsec, close to the resolution of the Hard X-ray Imaging Spectrometer on SMM which also imaged this flare. The Hard X-ray Burst Spectrometer determined the spectrum of the burst in the range 25-512 keV, and several patrol telescopes recorded the microwave time profile at frequencies from 2.8 to 19.6 GHz. The combined data show that the derived number of microwave-emitting electrons is at least three orders of magnitude fewer than the number of thick target electrons producing the hard X-rays. It is proposed that the fast electrons are highly beamed and radiate gyrosynchrotron emission less efficiently than isotropically distributed electrons.

  19. Short-range order in Fe-based metallic glasses: Wide-angle X-ray scattering studies

    SciTech Connect

    Babilas, Rafał; Hawełek, Łukasz; Burian, Andrzej

    2014-11-15

    The local atomic structure of the Fe{sub 80}B{sub 20}, Fe{sub 70}Nb{sub 10}B{sub 20} and Fe{sub 62}Nb{sub 8}B{sub 30} glasses prepared in the form of ribbons has been studied by wide-angle X-ray scattering. Structural information about the amorphous ribbons has been derived from analysis of the radial distribution functions using the least-squares curve-fitting method. The obtained structural parameters indicate that Fe–Fe, Fe–B, Fe–Nb and Nb–B contributions are involved in the near-neighbor coordination spheres. The possible similarities of the local atomic arrangement in the investigated glasses and the crystalline Fe{sub 3}B, Fe{sub 23}B{sub 6} and bcc Fe structures are also discussed. - Graphical abstract: Pair distribution functions (a) and best-fit model and experimental radial distribution functions for Fe{sub 80}B{sub 20} (b), Fe{sub 70}Nb{sub 10}B{sub 20} (c) and Fe{sub 62}Nb{sub 8}B{sub 30} (d) metallic glasses. - Highlights: • The short-range ordering in the Fe-based metallic glasses is presented. • The results of RDF function have been analyzed using the least-squares method. • The Fe–Fe, Fe–B, Fe–Nb or Nb–B contributions are involved in coordination spheres. • The structural unit is distorted triangular prism containing B, Fe or Nb atoms. • Similarities of atomic arrangement in glassy and crystalline structures are discussed.

  20. Small area silicon diffused junction x-ray detectors

    SciTech Connect

    Walton, J.T.; Pehl, R.H.; Larsh, A.E.

    1981-10-01

    The low temperature performance of silicon diffused junction detectors in the measurement of low energy x-rays is reported. The detectors have an area of 0.04 cm/sup 2/ and a thickness of 100 ..mu..m. The spectral resolutions of these detectors were found to be in close agreement with expected values indicating that the defects introduced by the high temperature processing required in the device fabrication were not deleteriously affecting the detection of low energy x-rays. Device performance over a temperature range of 77 to 150/sup 0/K is given. These detectors were designed to detect low energy x-rays in the presence of minimum ionizing electrons. The successful application of silicon diffused junction technology to x-ray detector fabrication may facilitate the development of other novel silicon x-ray detector designs.

  1. On X-Ray Variability in Seyfert Galaxies

    NASA Technical Reports Server (NTRS)

    Turner, T. J.; George, I. M.; Nandra, K.; Turcan, D.

    1999-01-01

    This paper presents a quantification of the X-ray variability amplitude for 79 ASCA observations of 36 Seyfert 1 galaxies. We find that consideration of sources with the narrowest permitted lines in the optical band introduces scatter into the established correlation between X-ray variability and nuclear luminosity. Consideration of the X-ray spectral index and variability properties together shows distinct groupings in parameter space for broad and narrow-line Seyfert 1 galaxies, confirming previous studies. A strong correlation is found between hard X-ray variability and FWHM Hbeta. A range of nuclear mass and accretion rate across the Seyfert population can explain the differences observed in X-ray and optical properties. An attractive alternative model, which does not depend on any systematic difference in central mass, is that the circumnuclear gas of NLSy1s is different to BLSy1s in temperature, optical depth, density or geometry.

  2. Small area silicon diffused junction X-ray detectors

    NASA Technical Reports Server (NTRS)

    Walton, J. T.; Pehl, R. H.; Larsh, A. E.

    1982-01-01

    The low-temperature performance of silicon diffused junction detectors in the measurement of low energy X-rays is reported. The detectors have an area of 0.04 sq cm and a thickness of 100 microns. The spectral resolutions of these detectors were found to be in close agreement with expected values, indicating that the defects introduced by the high-temperature processing required in the device fabrication were not deleteriously affecting the detection of low-energy X-rays. Device performance over a temperature range of 77 K to 150 K is given. These detectors were designed to detect low-energy X-rays in the presence of minimum ionizing electrons. The successful application of silicon-diffused junction technology to X-ray detector fabrication may facilitate the development of other novel silicon X-ray detector designs.

  3. Benchmark oxygen-oxygen pair-distribution function of ambient water from x-ray diffraction measurements with a wide Q-range

    SciTech Connect

    Skinner, Lawrie B.; Huang, Congcong; Schlesinger, Daniel; Pettersson, Lars G. M.; Nilsson, Anders; Benmore, Chris J.

    2013-02-21

    Four recent x-ray diffraction measurements of ambient liquid water are reviewed here. Each of these measurements represents a significant development of the x-ray diffraction technique applied to the study of liquid water. Sources of uncertainty from statistical noise, Q-range, Compton scattering, and self-scattering are discussed. The oxygen-hydrogen contribution to the measured x-ray scattering pattern was subtracted using literature data to yield an experimental determination, with error bars, of the oxygen-oxygen pair-distribution function, g{sub OO}(r), which essentially describes the distribution of molecular centers. The extended Q-range and low statistical noise of these measurements has significantly reduced truncation effects and related errors in the g{sub OO}(r) functions obtained. From these measurements and error analysis, the position and height of the nearest neighbor maximum in g{sub OO}(r) were found to be 2.80(1) A and 2.57(5) respectively. Numerical data for the coherent differential x-ray scattering cross-section I{sub X}(Q), the oxygen-oxygen structure factor S{sub OO}(Q), and the derived g{sub OO}(r) are provided as benchmarks for calibrating force-fields for water.

  4. Comparative Studies of Hard X-Ray Spectral Evolution in Solar Flares with High-Energy Proton Events Observed at Earth

    NASA Astrophysics Data System (ADS)

    Kiplinger, Alan L.

    1995-11-01

    This paper presents the results of two extensive studies of hard X-ray spectral evolution in solar flares and their associations with energetic interplanetary proton events. The focus of this work is to establish the degree to which events that display progressively hardening hard X-ray spectra, at any time and over all observable timescales, are associated with high-energy interplanetary proton events. The first study examined a sample of 152 hard X-ray flares well observed with the HXRBS instrument on the Solar Maximum Mission (SMM). The study showed that 22 events revealed a progressive spectral hardening either over flux peaks (i.e., a soft-hard- harder spectral evolution) or during flux decays and that 18 of these 22 events (82%) had associated 10 MeV proton events or enhancements. Conversely, the absence of spectral hardening is associated with the absence of interplanetary protons with 124 of the 130 remaining flares (95.4%). Since the hard X-ray counting rate threshold of the first study was sufficiently high (5000 counts s-1) to exclude many flares (more than 36%) associated with the largest interplanetary proton events, a second study was conducted using 193 less intense HXRBS events (a one out of three sample) and their associations with only large proton events. This study also identifies events with progressive spectral hardening. It also employs selection criteria suggested by the results of the first study to "predict" which flares would or would not have associated large proton events. This prescription for "predicting" proton events did so correctly for four large (SESC qualified) proton events, missed none, and produced only one "false alarm" in which the criteria were met but only a small proton event was seen at earth. Thus, a correct "prediction" was made for all but one of the 193 events. The results of the first study are then combined with the weighted results of the one out of three study, using the same selection criteria, to project correctly predicted associations of 22 out of 23 SESC events, for a 96% success rate, while 700 out of 708 flares were projected to be correct rejections with no associated proton events. The data suggest that progressive hardening is a diagnostic of high-energy particle acceleration of electrons and of protons and that it is not a manifestation of the "big flare syndrome" which asserts that the largest flares are associated with many or most known phenomena. There also appears to be an approximate relationship between the timescales (FWHM) of progressively hardening X-ray peaks and the cube of the interplanetary peak proton fluxes. The strong associations of particular hard X-ray characteristics and interplanetary proton events are of interest both on physical grounds and because the techniques employed can be directly adapted into a practical means of predicting which events are most likely to be associated with large interplanetary proton events that pose threats to humans in space and to spacecraft.

  5. Towards attosecond X-ray pulses from the FEL

    SciTech Connect

    Zholents, Alexander A.; Fawley, William M.

    2004-07-01

    The ability to study ultrafast phenomena has been recently advanced by the demonstrated production and measurement of a single, 650-attosecond (10{sup 18} sec), VUV x-ray pulse[1] and, latter, a 250-attosecond pulse[2]. The next frontier is a production of the x-ray pulses with shorter wavelengths and in a broader spectral range. Several techniques for a generation of an isolated, attosecond duration, short-wavelength x-ray pulse based upon the ponderomotive laser acceleration [3], SASE and harmonic cascade FELs ([4] - [6]) had been already proposed. In this paper we briefly review a technique proposed in [5] and present some new results.

  6. Miniature x-ray source

    DOEpatents

    Trebes, James E. (Livermore, CA); Stone, Gary F. (Livermore, CA); Bell, Perry M. (Tracy, CA); Robinson, Ronald B. (Modesto, CA); Chornenky, Victor I. (Minnetonka, MN)

    2002-01-01

    A miniature x-ray source capable of producing broad spectrum x-ray emission over a wide range of x-ray energies. The miniature x-ray source comprises a compact vacuum tube assembly containing a cathode, an anode, a high voltage feedthru for delivering high voltage to the anode, a getter for maintaining high vacuum, a connection for an initial vacuum pump down and crimp-off, and a high voltage connection for attaching a compact high voltage cable to the high voltage feedthru. At least a portion of the vacuum tube wall is highly x-ray transparent and made, for example, from boron nitride. The compact size and potential for remote operation allows the x-ray source, for example, to be placed adjacent to a material sample undergoing analysis or in proximity to the region to be treated for medical applications.

  7. Low Energy X-Ray Spectrometer

    NASA Astrophysics Data System (ADS)

    Woodruff, Wayne R.

    1981-10-01

    A subkilovolt spectrometer has been produced to permit high-energy-resolution, time-dependent x-ray intensity measurements. The diffracting element is a curved mica (d=9.95) crystal. To preclude higher order (n?1) diffractions, a carbon x-ray mirror that reflects only photons with energies less than 1.1 keV is utilized ahead of the diffracting element. The nominal energy range of interest is 800 to 900 eV. The diffracted photons are detected by a gold-surfaced photoelectric diode designed to have a very good frequency response, and whose current is recorded on an oscilloscope. A thin, aluminum light barrier is placed between the diffracting crystal and the photoelectric diode detector to keep any UV generated on or scattered by the crystal from illuminating the detector. High spectral enegy resolution is provided by many photocathodes between 8- and 50-eV wide placed serially along the diffracted x-ray beam at the detector position. The spectrometer was calibrated for energy and energy dispersion using the Ni L?1,2 lines produced in the LLNL IONAC accelerator and in third order using a molybdenum target x-ray tube. For the latter calibration the carbon mirror was replaced by one surfaced with rhodium to raise the cut-off energy to about 3 keV. The carbon mirror reflection dependence on energy was measured using one of our Henke x-ray sources. The curved mica crystal diffraction efficiency was measured on our Low-Energy X-ray (LEX) machine. The spectrometer performs well although some changes in the way the x-ray mirror is held are desirable.

  8. Low energy x-ray spectrometer

    SciTech Connect

    Woodruff, W.R.

    1981-06-05

    A subkilovolt spectrometer has been produced to permit high-energy-resolution, time-dependent x-ray intensity measurements. The diffracting element is a curved mica (d = 9.95A) crystal. To preclude higher order (n > 1) diffractions, a carbon x-ray mirror that reflects only photons with energies less than approx. 1.1 keV is utilized ahead of the diffracting element. The nominal energy range of interest is 800 to 900 eV. The diffracted photons are detected by a gold-surface photoelectric diode designed to have a very good frequency response, and whose current is recorded on an oscilloscope. A thin, aluminium light barrier is placed between the diffracting crystal and the photoelectric diode detector to keep any uv generated on or scattered by the crystal from illuminating the detector. High spectral energy resolution is provided by many photocathodes between 8- and 50-eV wide placed serially along the diffracted x-ray beam at the detector position. The spectrometer was calibrated for energy and energy dispersion using the Ni L..cap alpha../sub 1/ /sub 2/ lines produced in the LLNL IONAC accelerator and in third order using a molybdenum target x-ray tube. For the latter calibration the carbon mirror was replaced by one surfaced with rhodium to raise the cut-off energy to about 3 keV. The carbon mirror reflection dependence on energy was measured using one of our Henke x-ray sources. The curved mica crystal diffraction efficiency was measured on our Low-Energy x-ray (LEX) machine. The spectrometer performs well although some changes in the way the x-ray mirror is held are desirable. 16 figures.

  9. Advanced x-ray imaging spectrometer

    NASA Technical Reports Server (NTRS)

    Callas, John L. (Inventor); Soli, George A. (Inventor)

    1998-01-01

    An x-ray spectrometer that also provides images of an x-ray source. Coded aperture imaging techniques are used to provide high resolution images. Imaging position-sensitive x-ray sensors with good energy resolution are utilized to provide excellent spectroscopic performance. The system produces high resolution spectral images of the x-ray source which can be viewed in any one of a number of specific energy bands.

  10. A galactic component of the diffuse X-ray flux in the range 2-7 keV

    NASA Astrophysics Data System (ADS)

    Protheroe, R. J.; Wolfendale, A. W.; Wdowczyk, J.

    1980-08-01

    An analysis of the spatial distribution of the 2-7 keV X-ray background measured by Uhuru and reported by Schwartz (1979) is presented. The latitude distribution above 10 deg is consistent with a uniform isotropic component comprising the bulk of the radiation plus a galactic part varying from 3% at /b/ = 20 deg to 1% at /b/ = 90 deg. An analysis was made of the residual background based on the work of Warwick, Pye, and Fabian, in terms of a directional anisotropy as indicated by the Compton-Getting effect; the symmetrical galactic contribution was subtracted in the computations. It was shown that the results are consistent with the solar system moving through the 2-7 keV X-ray sea in the same manner as it appears to move with respect to the 2.7 K radiation.

  11. A galactic component of the diffuse X-ray flux in the range 2-7 keV

    NASA Technical Reports Server (NTRS)

    Protheroe, R. J.; Wolfendale, A. W.; Wdowczyk, J.

    1980-01-01

    An analysis of the spatial distribution of the 2-7 keV X-ray background measured by Uhuru and reported by Schwartz (1979) is presented. The latitude distribution above 10 deg is consistent with a uniform isotropic component comprising the bulk of the radiation plus a galactic part varying from 3% at /b/ = 20 deg to 1% at /b/ = 90 deg. An analysis was made of the residual background based on the work of Warwick, Pye, and Fabian, in terms of a directional anisotropy as indicated by the Compton-Getting effect; the symmetrical galactic contribution was subtracted in the computations. It was shown that the results are consistent with the solar system moving through the 2-7 keV X-ray sea in the same manner as it appears to move with respect to the 2.7 K radiation.

  12. Transmission crystal x-ray spectrometer covering the 6 keV-18 keV energy range with E∕ΔE = 1800 instrumental resolving power.

    PubMed

    Seely, John; Feldman, Uri; Brown, Charles; Pereira, Nino; Hudson, Lawrence; Glover, Jack; Silver, Eric

    2012-10-01

    A high-resolution x-ray spectrometer utilizing a thin quartz transmission crystal and covering the 6 keV-18 keV energy range has been developed and tested. The spectrometer consists of a cylindrically bent crystal in a vacuum housing. The crystal position and the range of Bragg angles that are incident on the crystal can be adjusted to record an ≈4 keV wide spectrum in the 6 keV-18 keV range. The spectrometer is of the Cauchois type and has a compact linear geometry that is convenient for deployment at laser-produced plasma, EBIT, and other x-ray sources. Test spectra of the W L and Mo K lines from laboratory sources have linewidths as small as 11 eV, approaching the natural widths, and instrumental resolving power as high as 1800. Techniques for enhancing the energy resolution are experimentally demonstrated. PMID:23126934

  13. X-ray Spectroscopy of Stellar Coronae: History - Present - Future

    NASA Astrophysics Data System (ADS)

    Mewe, Rolf

    1996-12-01

    Since in 1948 X-rays were detected from the solar corona, stellar coronae were among the first predicted non-solar X-ray sources. However, because of their relatively low X-ray luminosity, the first non-solar stellar corona was not detected in X-rays until 1974 - twelve years after the discovery of the first non-solar X-ray source. After the 1980s, with the advent of sensitive X-ray imaging instruments on board the EINSTEIN, EXOSAT, and later the ROSAT observatories, the study of stellar coronae has become a vastly growing field of research. These X-ray observations have demonstrated that X-ray emitting coronae are a common feature among stars on the cool side of the Hertzsprung-Russell diagram, with the probable exception of single very cool giant and supergiant stars and A-type dwarfs. The instruments on board these satellites provided for the first time a taste of what can be achieved with X-ray spectroscopy and with the advent of the EUVE (1992) and ASCA (1993), detailed spectroscopy of stellar coronae in the EUV and X-ray regimes got off to a real start. The observations have permitted the identification of coronal material at different temperatures whose existence relates to a range of possible magnetic loop structures in the hot outer atmospheres of stars. The higher spectral resolution of the next generation of spectrometers on board NASA's AXAF (1998), ESA's XMM (1999), and the Japanese ASTRO-E (2000) will improve the determination of coronal temperature structure, abundances, and densities from which loop geometries can be derived and will enable velocity diagnostics. This paper reviews our present knowledge of observational stellar X-ray spectroscopy up to EUVE and ASCA and briefly discusses the perspectives for coronal diagnostics offered by AXAF, XMM, and ASTRO-E.

  14. Mid- and Near-infrared spectral properties of a sample of Swift-BAT X-ray selected AGNs

    NASA Astrophysics Data System (ADS)

    Castro, Angel; Miyaji, Takamitsu; Malkan, Matthew A.; Ichikawa, Kohei; Ueda, Yoshihiro; Shirahata, M.; Nakagawa, Takao; Imanishi, Masatoshi; Oyabu, Shinki

    2015-08-01

    We present a comparative study of the mid- (MIR) to near-infrared (NIR) properties of a sample of X-ray selected AGNs from the Swift/Burst Alert Telescope (BAT) 70-month all-sky hard X-ray (14-195 keV) survey. For a sample of 78 AGNs, including both Seyfert 1 and Seyfert 2 sources with black hole masses derived from 2MASS K-band magnitudes and literature, we obtain spectroscopic data from the IRC (2.5 - 5 ?m) and IRS (in the 5-14 ?m band) instruments onboard the Akari and Spitzer satellites, respectively. We test possible correlations between the 3.3, 6.2, 7.7, 8.6, 11.2 and 12.7 ?m polycyclic aromatic hydrocarbon (PAH) emission features, the continuum slope and CO optical depth, as well as CO2, H2O, and amorphous silicates. Using the 3.3, 6.2 and 11.3 ?m PAH emission features as a proxy for the star-formation rate (SFR) we report the AGN type and Eddington-ratio dependences of circum-nuclear star formation.

  15. Quasi-periodic Oscillations Associated with Spectral Branches in Rossi X-Ray Timing Explorer Observations of Circinus X-1

    NASA Astrophysics Data System (ADS)

    Shirey, Robert E.; Bradt, Hale V.; Levine, Alan M.; Morgan, Edward H.

    1998-10-01

    We present Rossi X-Ray Timing Explorer (RXTE) All-Sky Monitor observations of the X-ray binary Circinus X-1 that illustrate the variety of intensity profiles associated with the 16.55 day flaring cycle of the source. We also present eight observations of Cir X-1 made with the RXTE Proportional Counter Array over the course of a cycle wherein the average intensity of the flaring state decreased gradually over ~12 days. Fourier power density spectra for these observations show a narrow quasi-periodic oscillation (QPO) peak that shifts in frequency between 6.8 and 32 Hz, as well as a broad QPO peak that remains roughly stationary at ~4 Hz. We identify these as Z-source horizontal and normal branch oscillations (HBOs/NBOs), respectively. Color-color and hardness-intensity diagrams (CDs/HIDs) show curvilinear tracks for each of the observations. The properties of the QPOs and very low frequency noise allow us to identify segments of these tracks with Z-source horizontal, normal, and flaring branches that shift location in the CDs and HIDs over the course of the 16.55 day cycle. These results contradict a previous prediction, based on the hypothesis that Cir X-1 is a high-? atoll source, that HBOs should never occur in this source.

  16. X-ray absorption spectral studies of copper(II) mixed ligand complexes having ethylenediamine as one of the ligands

    NASA Astrophysics Data System (ADS)

    Dwivedi, Shikha; Joshi, S. K.; Hinge, V. K.; Shrivastava, B. D.; Prasad, J.; Srivastava, K.

    2014-09-01

    X-ray absorption spectra of copper(II) mixed ligand complexes, having ethylenediamine (en) as one of the ligands, have been recorded at the K-edge of copper at the dispersive extended X- ray absorption fine structure (EXAFS) beamline (BL-8) at the 2.5 GeV INDUS-2 Synchrotron, RRCAT, Indore, India. The samples studied are: Cu(en)2(ClO4)2, Cu(en)2Br2.H2O and Cu(en)2SO4. The data obtained has been processed using EXAFS data analysis program Athena. The K-edge has been found to split in two edges K and K' in each of the complex. The energies of the edges K(EK) and K'(EK') and the principal absorption maximum A(EA) have been determined from the derivative spectra. The chemical shift has been utilized to determine the oxidation state of copper in the complexes and to estimate effective nuclear charge (ENC) on the absorbing atom. The EXAFS data has been used to determine the bond lengths in the complexes using three different graphical methods. The bond lengths, obtained from one of these methods and the Fourier transformation method, are comparable with each other, showing that both of these methods give phase uncorrected bond lengths.

  17. Bone densitometry using x-ray spectra

    NASA Astrophysics Data System (ADS)

    Krmar, M.; Shukla, S.; Ganezer, K.

    2010-10-01

    In contrast to the two distinct energy regions that are involved in dual-energy x-ray absorptiometry for bone densitometry, the complete spectrum of a beam transmitted through two layers of different materials is utilized in this study to calculate the areal density of each material. Test objects constructed from aluminum and Plexiglas were used to simulate cortical bone and soft tissue, respectively. Solid-state HPGe (high-purity germanium) detectors provided high-resolution x-ray spectra over an energy range of approximately 20-80 keV. Areal densities were obtained from spectra using two methods: a system of equations for two spectral regions and a nonlinear fit of the entire spectrum. Good agreement with the known areal densities of aluminum was obtained over a wide range of PMMA thicknesses. The spectral method presented here can be used to decrease beam hardening at a small number of bodily points selected for examination.

  18. Multilayer Monochromator For Hard X Rays And Gamma Rays

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.

    1992-01-01

    Compact monochromator for hard x rays and gamma rays provides high spectral resolution with high throughput. Resembles instruments in "Compact X-Ray and Extreme-Ultraviolet Monochromator" (MFS-28499), "Scanning X-Ray or Extreme-Ultraviolet Monochromator" (MFS-28492), "Ultra-High-Spectral-Resolution X-Ray/EUV Monochromator" (MFS-28500), and "Four-Mirror X-Ray and Extreme-Ultraviolet Monochromator" (MFS-28498). Operates on principle of multilayer Bragg reflector. Used in nuclear, astronomical, and biomedical research, x-ray crystallography, research on processing materials, research in x-ray lasers, and x-ray lithography.

  19. X-RAY MONITORING OF ULTRALUMINOUS X-RAY SOURCES

    SciTech Connect

    Kaaret, Philip; Feng Hua

    2009-09-10

    X-ray monitoring observations were performed with the Swift observatory of the ultraluminous X-ray sources Holmberg IX X-1, NGC 5408 X-1, and NGC 4395 X-2 and also of the nuclear X-ray source in NGC 4395. Holmberg IX X-1 remains in the hard X-ray spectral state as its flux varies by a factor of 7 up to a (isotropic) luminosity of 2.8 x 10{sup 40} erg s{sup -1}. This behavior may suggest an unusually massive compact object. We find excess power at periods near 60 days and 28 days in the X-ray emission from Holmberg IX X-1. Additional monitoring is required to test the significance of these signals. NGC 5408 X-1 and NGC 4395 X-2 appear to remain in the soft spectral state found by Chandra and XMM with little variation in spectral hardness even as the luminosity changes by a factor of 9. We found an outburst from the nuclear source in NGC 4395 reaching an X-ray luminosity of 9 x 10{sup 40} erg s{sup -1}, several times higher than any previously reported.

  20. A broad spectral feature detected during the cooling phase of a thermonuclear X-ray burst from GRS 1747-312 with Suzaku

    NASA Astrophysics Data System (ADS)

    Iwai, Masachika; Dotani, Tadayasu; Ozaki, Masanobu; Maeda, Yoshitomo; Mori, Hideyuki; Saji, Shigetaka

    2015-08-01

    Precise measurement of the mass-radius relation of a Neutron Star (NS) is crucial to determine the equation of state of the ultra dense matter. Instead of directly measuring the mass and radius, it is often measured the mass-radius ratio, i.e. gravitational redshift at the NS surface, as it is free from the uncertainty to the source distance. If we can detect spectral features in the emission from the NS photosphere, which may be observable during the thermonuclear X-ray bursts, we can directly measure the gravitational redshift. Thus, we are systematically analyzing the Suzaku archival data looking for the thermonuclear X-ray bursts.GRS 1747-312 is a type I X-ray burst source located in the globular cluster Terzan 6. It was observed with Suzaku as a part of Galactic bulge mapping observations in September, 2009, for a total exposure of 45.3 ks. An exceptionally large X-ray burst with photospheric radius expansion was detected during the observation. The burst duration exceeded an hour. Unfortunately, most of the decay of the burst was not observed due to the satellite passage through the South Atlantic Anomaly.We detected a broad feature in the energy spectrum of the burst above 7 keV in its cooling phase. The feature resembled that of an absorption edge, but was significantly smeared. We found that it was best reproduced by a rotation-broadened absorption edge, where the photo-electric absorption edge was smeared by the rapid spin of the NS. The smeared edge may be produced by the dominant products of the X-ray burst, i.e. hydrogen-like Fe (9.28 keV) or Ni (10.78 keV). If this identification is correct, the gravitational red shift would be 1.30+-0.02 or 1.51+-0.02, respectively, corresponding to the NS radius of 10.1+-0.3 or 7.4+-0.1 km, for an assumed NS mass of 1.4 solar mass. Because the absorption edge is not completely smeared out even with the rapid spin of the NS, this can be a powerful tool to measure the gravitational redshift of the NSs.

  1. NEW X-RAY DETECTIONS OF WNL STARS

    SciTech Connect

    Skinner, Stephen L.; Zhekov, Svetozar A.; Guedel, Manuel; Schmutz, Werner; Sokal, Kimberly R.

    2012-05-15

    Previous studies have demonstrated that putatively single nitrogen-type Wolf-Rayet stars (WN stars) without known companions are X-ray sources. However, almost all WN star X-ray detections so far have been of earlier WN2-WN6 spectral subtypes. Later WN7-WN9 subtypes (also known as WNL stars) have proved more difficult to detect, an important exception being WR 79a (WN9ha). We present here new X-ray detections of the WNL stars WR 16 (WN8h) and WR 78 (WN7h). These new results, when combined with previous detections, demonstrate that X-ray emission is present in WN stars across the full range of spectral types, including later WNL stars. The two WN8 stars observed to date (WR 16 and WR 40) show unusually low X-ray luminosities (L{sub x} ) compared to other WN stars, and it is noteworthy that they also have the lowest terminal wind speeds (v{sub {infinity}}). Existing X-ray detections of about a dozen WN stars reveal a trend of increasing L{sub x} with wind luminosity L{sub wind} = (1/2)M-dot v{sup 2}{sub {infinity}}, suggesting that wind kinetic energy may play a key role in establishing X-ray luminosity levels in WN stars.

  2. Soft x-ray solar polarimeter-spectrometer

    NASA Astrophysics Data System (ADS)

    Steślicki, Marek; Sylwester, Janusz; Siarkowski, Marek; Kowaliński, Mirosław; Płocieniak, Stefan; Bąkała, Jarosław; Szaforz, Żaneta; Kuzin, Sergey

    2014-12-01

    We present an innovative soft X-ray polarimeter and spectrometer SOLPEX, the instrument to be mounted aboard the International Space Station (ISS) in 2015/2016. The SOLPEX will be composed of three individual measuring units: the soft X-ray polarimeter with 1-2% linear polarization detection limit, a fast-rotating drum X-ray spectrometer with very high time resolution (0.1s) and a simple pin-hole soft X-ray imager-spectrometer with moderate spatial (~20arcsec), spectral (0.5 keV) and high time resolution (0.1s). This set of instruments will provide unique opportunity to complement the efforts to reliably measure the X-ray polarization and contribute towards understanding the physics of solar flares. The standard flare model states that electrons are being accelerated in specific regions of the corona at or near magnetic reconnection site and then propagate along reconnected magnetic field lines toward the atmospheric denser layers. There, they are decelerated and lose their energy mainly through the bremsstrahlung process. Deposited energy is readily converted to directed evaporation of the plasma to be detected through the Doppler-shifted emission lines in extreme ultraviolet and soft X-ray spectral ranges Due to highly anisotropic character of impulsive phase electron beams, resulting emission is expected to be polarized. Both these processes: bremsstrahlung emission of supposedly polarized X-ray flux and accompanying plasma evaporation velocities are to be simultaneously observed by the proposed SOLPEX instruments.

  3. X-Ray Properties of K-Selected Galaxies at 0.5 Less than z Less than 2.0: Investigating Trends with Stellar Mass, Redshift and Spectral Type

    NASA Technical Reports Server (NTRS)

    Jones, Therese M.; Kriek, Mariska; vanDokkum, Peter G.; Brammer, Gabriel; Franx, Marijn; Greene, Jenny E.; Labbe, Ivo; Whitaker, Katherine E.

    2014-01-01

    We examine how the total X-ray luminosity correlates with stellar mass, stellar population, and redshift for a K-band limited sample of approximately 3500 galaxies at 0.5 < z < 2.0 from the NEWFIRM Medium Band Survey in the COSMOS field. The galaxy sample is divided into 32 different galaxy types, based on similarities between the spectral energy distributions. For each galaxy type, we further divide the sample into bins of redshift and stellar mass, and perform an X-ray stacking analysis using the Chandra COSMOS data. We find that full band X-ray luminosity is primarily increasing with stellar mass, and at similar mass and spectral type is higher at larger redshifts. When comparing at the same stellar mass, we find that the X-ray luminosity is slightly higher for younger galaxies (i.e., weaker 4000 angstrom breaks), but the scatter in this relation is large. We compare the observed X-ray luminosities to those expected from low- and high-mass X-ray binaries (XRBs). For blue galaxies, XRBs can almost fully account for the observed emission, while for older galaxies with larger 4000 angstrom breaks, active galactic nuclei (AGN) or hot gas dominate the measured X-ray flux. After correcting for XRBs, the X-ray luminosity is still slightly higher in younger galaxies, although this correlation is not significant. AGN appear to be a larger component of galaxy X-ray luminosity at earlier times, as the hardness ratio increases with redshift. Together with the slight increase in X-ray luminosity this may indicate more obscured AGNs or higher accretion rates at earlier times.

  4. Bent crystal spectrometer for solar X-ray spectroscopy

    NASA Technical Reports Server (NTRS)

    Rapley, C. G.; Culhane, J. L.; Acton, L. W.; Catura, R. C.; Joki, E. G.; Bakke, J. C.

    1977-01-01

    A bent crystal spectrometer employs a collimated beam of X-rays incident on the crystal over a range of Bragg angles determined by the orientation and curvature of the crystal surface. It provides continuous and simultaneous coverage of all X-ray wavelengths within its spectral range. In-flight testing for solar X-ray spectroscopy was performed using a small instrument to supplement the wavelength coverage of several scanning spectrometers used to study solar active regions in the 9-24 A range. Later testing included modifications to alleviate problems caused by ultraviolet radiation. Future usage of the device will include studies of time variable emission from solar flares or discrete galactic X-ray sources, and the first major experiment to utilize bent crystal spectrometers will be the Solar Maximum Mission satellite in 1979.

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

    NASA Technical Reports Server (NTRS)

    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.

  6. X-ray imaging and x-ray source development at Lawrence Livermore National Laboratory

    SciTech Connect

    Trebes, J.; Balhorn, R.; Anderson, E.

    1993-12-01

    The Laser Program at Lawrence Livermore National Laboratory has a continuing effort to develop both x-ray sources and x-ray sources and x-ray microscopy. This effort includes the ongoing development of: (1) a wide range of x-ray lasers at the Nova Laser Facility, (2) a zone plate lens--multilayer mirror based x-ray microscope (3) three dimensional, high resolution x-ray microscopy (4) short wavelength, normal incidence multilayer x-ray mirrors, (5) compact, high average power lasers for producing x-ray lasers and laser plasma x-ray sources. We have constructed and operated an x-ray laser based transmission x-ray microscope. The advantage offered by the x-ray laser source is the extreme high brightness allows high resolution images to be made on a timescale faster than that for x-ray damage effects to appear. The microscope, consists of: the x-ray laser, a multilayer coated, near normal incidence spherical mirror used as a condenser, a silicon nitride specimen holder, an x-ray zone plate used as an objective lens, and a microchannel plate x-ray detector. The x-ray laser used is the Ni-like Ta x-ray laser operating with a wavelength of 4.48 nm, a pulselength of 200 spec, a divergence of 10 mrad, and an output energy of 10 microjoules.

  7. Black hole mass determination in the X-ray binary 4U 1630-47: Scaling of spectral and variability characteristics

    SciTech Connect

    Seifina, Elena; Shaposhnikov, Nikolai E-mail: titarchuk@fe.infn.it E-mail: nikolai.v.shaposhnikov@nasa.gov

    2014-07-01

    We present the results of a comprehensive investigation on the evolution of spectral and timing properties of the Galactic black hole candidate 4U 1630-47 during its spectral transitions. In particular, we show how a scaling of the correlation of the photon index of the Comptonized spectral component Γ with low-frequency quasi-periodic oscillations (QPOs), ν {sub L}, and mass accretion rate, M-dot , can be applied to the black hole mass and the inclination angle estimates. We analyze the transition episodes observed with the Rossi X-Ray Timing Explorer and BeppoSAX satellites. We find that the broadband X-ray energy spectra of 4U 1630-47 during all spectral states can be modeled by a combination of a thermal component, a Comptonized component, and a red-skewed iron-line component. We also establish that Γ monotonically increases during transition from the low-hard state to the high-soft state and then saturates for high mass accretion rates. The index saturation levels vary for different transition episodes. Correlations of Γ versus ν {sub L} also show saturation at Γ ∼ 3. Γ-- M-dot and Γ-ν {sub L} correlations with their index saturation revealed in 4U 1630-47 are similar to those established in a number of other black hole candidates and can be considered as an observational evidence for the presence of a black hole in these sources. The scaling technique, which relies on XTE J1550-564, GRO 1655-40, and H1743-322 as reference sources, allows us to evaluate a black hole mass in 4U 1630-47 yielding M {sub BH} ∼ 10 ± 0.1 solar masses and to constrain the inclination angle of i ≲ 70°.

  8. The XMM-Newton Wide-Field Survey in the COSMOS Field. IV. X-Ray Spectral Properties of Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Mainieri, V.; Hasinger, G.; Cappelluti, N.; Brusa, M.; Brunner, H.; Civano, F.; Comastri, A.; Elvis, M.; Finoguenov, A.; Fiore, F.; Gilli, R.; Lehmann, I.; Silverman, J.; Tasca, L.; Vignali, C.; Zamorani, G.; Schinnerer, E.; Impey, C.; Trump, J.; Lilly, S.; Maier, C.; Griffiths, R. E.; Miyaji, T.; Capak, P.; Koekemoer, A.; Scoville, N.; Shopbell, P.; Taniguchi, Y.

    2007-09-01

    We present a detailed spectral analysis of pointlike X-ray sources in the XMM-Newton COSMOS field. Our sample of 135 sources only includes those that have more than 100 net counts in the 0.3-10 keV energy band and have been identified through optical spectroscopy. The majority of the sources are well described by a simple power-law model with either no absorption (76%) or a significant intrinsic, absorbing column (20%). The remaining ~4% of the sources require a more complex modeling by incorporating additional components to the power law. For sources with more than 180 net counts (bright sample), we allowed both the photon spectral index Γ and the equivalent hydrogen column NH to be free parameters. For fainter sources, we fix Γ to the average value and allow NH to vary. The mean spectral index of the 82 sources in the bright sample is <Γ>=2.06+/-0.08, with an intrinsic dispersion of ~0.24. Each of these sources has fractional errors on the value of Γ below 20%. As expected, the distribution of intrinsic absorbing column densities is markedly different between AGNs with or without broad optical emission lines. We find within our sample four type 2 QSO candidates (LX>1044 ergs s-1, NH>1022 cm-2), with a spectral energy distribution well reproduced by a composite Seyfert 2 spectrum, that demonstrates the strength of the wide-field COSMOS XMM-Newton survey to detect these rare and underrepresented sources. In addition, we have identified a Compton-thick (NH>1.5×1024 cm-2) AGN at z=0.1248. Its X-ray spectrum is well fitted by a pure reflection model and a significant Fe Kα line at rest-frame energy of 6.4 keV. Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA.

  9. VARIABILITY AND SPECTRAL MODELING OF THE HARD X-RAY EMISSION OF GX 339-4 IN A BRIGHT LOW/HARD STATE

    SciTech Connect

    Droulans, R.; Belmont, R.; Malzac, J.; Jourdain, E.

    2010-07-10

    We study the high-energy emission of the Galactic black hole candidate GX 339-4 using INTEGRAL/SPI and simultaneous RXTE/PCA data. By the end of 2007 January, when it reached its peak luminosity in hard X-rays, the source was in a bright hard state. The SPectrometer on INTEGRAL (SPI) data from this period show a good signal-to-noise ratio, allowing a detailed study of the spectral energy distribution up to several hundred keV. As a main result, we report on the detection of a variable hard spectral feature ({>=}150 keV) which represents a significant excess with respect to the cutoff power-law shape of the spectrum. The SPI data suggest that the intensity of this feature is positively correlated with the 25-50 keV luminosity of the source and the associated variability timescale is shorter than 7 hr. The simultaneous Proportional Counter Array data, however, show no significant change in the spectral shape, indicating that the source is not undergoing a canonical state transition. We analyzed the broadband spectra in the lights of several physical models, assuming different heating mechanisms and properties of the Comptonizing plasma. For the first time, we performed quantitative model fitting with the new versatile Comptonization code BELM, accounting self-consistently for the presence of a magnetic field. We show that a magnetized medium subject to pure non-thermal electron acceleration provides a framework for a physically consistent interpretation of the observed 4-500 keV emission. Moreover, we find that the spectral variability might be triggered by the variations of only one physical parameter, namely the magnetic field strength. Therefore, it appears that the magnetic field is likely to be a key parameter in the production of the Comptonized hard X-ray emission.

  10. Black Hole Mass Determination In the X-Ray Binary 4U 1630-47: Scaling of Spectral and Variability Characteristics

    NASA Technical Reports Server (NTRS)

    Seifina, Elena; Titarchuk, Lev; Shaposhnikov, Nikolai

    2014-01-01

    We present the results of a comprehensive investigation on the evolution of spectral and timing properties of the Galactic black hole candidate 4U 1630-47 during its spectral transitions. In particular, we show how a scaling of the correlation of the photon index of the Comptonized spectral component gamma with low-frequency quasi-periodic oscillations (QPOs), ?(sub L), and mass accretion rate, M, can be applied to the black hole mass and the inclination angle estimates.We analyze the transition episodes observed with the Rossi X-Ray Timing Explorer and BeppoSAX satellites.We find that the broadband X-ray energy spectra of 4U 1630-47 during all spectral states can be modeled by a combination of a thermal component, a Comptonized component, and a red-skewed iron-line component. We also establish that gamma monotonically increases during transition from the low-hard state to the high-soft state and then saturates for high mass accretion rates. The index saturation levels vary for different transition episodes. Correlations of gamma versus ?(sub L) also show saturation at gamma (is) approximately 3. Gamma -M and gamma -?(sub L) correlations with their index saturation revealed in 4U 1630-47 are similar to those established in a number of other black hole candidates and can be considered as an observational evidence for the presence of a black hole in these sources. The scaling technique, which relies on XTE J1550-564, GRO 1655-40, and H1743-322 as reference sources, allows us to evaluate a black hole mass in 4U 1630-47 yielding M(sub BH) (is) approximately 10 +/- 0.1 solar masses and to constrain the inclination angle of i (is) approximately less than 70 deg.

  11. Determination of sulfur and chlorine in fodder by X-ray fluorescence spectral analysis and comparison with other analytical methods

    NASA Astrophysics Data System (ADS)

    Nečemer, Marijan; Kump, Peter; Rajčevič, Marija; Jačimović, Radojko; Budič, Bojan; Ponikvar, Maja

    2003-07-01

    Sulfur and chlorine are essential elements in the metabolic processes of ruminants, and correct planning strategy of ruminant nutrition should provide a sufficient content of S and Cl in the animal's body. S and Cl can be found in various types of animal fodder in the form of organic compounds and minerals. In this work, the Cl and S content in forage was determined by X-ray fluorescence spectrometry (XRF), and its performance was then compared in parallel analyses by instrumental neutron activation analysis (INAA), inductively coupled plasma atomic emission spectrometry (ICP-AES) and potentiometric methods. The results were compared and critically evaluated in order to assess the performance and capability of the XRF technique in analysis of animal fodder.

  12. The 2006-2007 Active Phase of Anomalous X-Ray Pulsar 4U 0142+61: Radiative and Timing Changes, Bursts,and Burst Spectral Features

    NASA Technical Reports Server (NTRS)

    Gavriil, Fotis P.; Dib, Rim; Kaspi, Victoria M.

    2011-01-01

    After at least 6 years of quiescence, Anomalous X-ray Pulsar (AXP) 4U 0142+61 entered an active phase in 2006 March that lasted several months and included six X-ray bursts as well as many changes in the persistent X-ray emission. The bursts, the first seen from this AXP in > 11 years of Rossi X-ray Timing Explorer monitoring, all occurred in the interval between 2006 April 6 and 2007 February 7. The burst durations ranged from 0.4 - 1.8 x 10(exp 3) s. The first five burst spectra are well modeled by blackbodies, with temperatures kT approx 2 - 9 keV. However, the sixth burst had a complicated spectrum that is well characterized by a blackbody plus two emission features whose amplitude varied throughout the burst. The most prominent feature was at 14.0 keV. Upon entry into the active phase the pulsar showed a significant change in pulse morphology and a likely timing glitch. The glitch had a total frequency jump of (1.9+/-0.4) x 10(exp -7) Hz, which recovered with a decay time of 17+/-2 days by more than the initial jump, implying a net spin-down of the pulsar. Within the framework of the magnetar model, the net spin-down of the star could be explained by regions of the superfluid that rotate. slower than the rest. The bursts, flux enhancements, and pulse morphology changes can be explained as arising from crustal deformations due to stresses imposed by the highly twisted internal magnetic field. However, unlike other AXP outbursts, we cannot account for a major twist being implanted in the magnetosphere.

  13. X-ray spectrum in the range (6-12) A emitted by laser-produced plasma of samarium

    SciTech Connect

    Louzon, Einat; Henis, Zohar; Levi, Izhak; Hurvitz, Gilad; Ehrlich, Yosi; Fraenkel, Moshe; Maman, Shlomo; Mandelbaum, Pinchas

    2009-05-15

    A detailed analysis of the x-ray spectrum emitted by laser-produced plasma of samarium (6-12 A) is presented, using ab initio calculations with the HULLAC relativistic code and isoelectronic considerations. Resonance 3d-nf (n=4 to 7), 3p-4d, 3d-4p, and 3p-4s transitions in Ni samarium ions and in neighboring ionization states (from Mn to Zn ions) were identified. The experiment results show changes in the fine details of the plasma spectrum for different laser intensities.

  14. X-Ray Imaging

    MedlinePLUS

    ... 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 ...

  15. Cosmic x ray physics

    NASA Technical Reports Server (NTRS)

    Mccammon, Dan; Cox, D. P.; Kraushaar, W. L.; Sanders, W. T.

    1990-01-01

    The annual progress report on Cosmic X Ray Physics is presented. Topics studied include: the soft x ray background, proportional counter and filter calibrations, the new sounding rocket payload: X Ray Calorimeter, and theoretical studies.

  16. Cosmic x ray physics

    NASA Technical Reports Server (NTRS)

    Mccammon, Dan; Cox, D. P.; Kraushaar, W. L.; Sanders, W. T.

    1991-01-01

    The annual progress report on Cosmic X Ray Physics for the period 1 Jan. to 31 Dec. 1990 is presented. Topics studied include: soft x ray background, new sounding rocket payload: x ray calorimeter, and theoretical studies.

  17. Joint x-ray

    MedlinePLUS

    X-ray - joint; Arthrography; Arthrogram ... x-ray technologist will help you position the joint to be x-rayed on the table. Once in place, pictures are taken. The joint may be moved into other positions for more ...

  18. X-Ray Diffraction Apparatus

    NASA Technical Reports Server (NTRS)

    Blake, David F. (Inventor); Bryson, Charles (Inventor); Freund, Friedmann (Inventor)

    1996-01-01

    An x-ray diffraction apparatus for use in analyzing the x-ray diffraction pattern of a sample is introduced. The apparatus includes a beam source for generating a collimated x-ray beam having one or more discrete x-ray energies, a holder for holding the sample to be analyzed in the path of the beam, and a charge-coupled device having an array of pixels for detecting, in one or more selected photon energy ranges, x-ray diffraction photons produced by irradiating such a sample with said beam. The CCD is coupled to an output unit which receives input information relating to the energies of photons striking each pixel in the CCD, and constructs the diffraction pattern of photons within a selected energy range striking the CCD.

  19. On the Nature of the Variability Power Decay towards Soft Spectral States in X-Ray Binaries. Case Study in Cyg X-1

    NASA Technical Reports Server (NTRS)

    Titarchuk, Lev; Shaposhinikov, Nikolai

    2007-01-01

    A characteristic feature of the Fourier Power Density Spectrum (PDS) observed from black hole X-ray binaries in low/hard and intermediate spectral states is a broad band-limited noise, characterized by a constant below some frequency (a "break" frequency) and a power law above this frequency. It has been shown that the variability of this type can be produced by the inward diffusion of the local driving perturbations in a bounded configuration (accretion disk or corona). In the framework of this model, the perturbation diffusion time to is related to the phenomenological break frequency, while the PDS power-law slope above the "break" is determined by the viscosity distribution over the configuration. The perturbation diffusion scenario explains the decay of the power of X-ray variability observed in a number of compact sources (containing black hole and neutron star) during an evolution of theses sources from low/hard to high/soft states. We compare the model predictions with the subset of data from Cyg X-1 collected by the Rossi X-ray Time Explorer (RXTE). Our extensive analysis of the Cyg X-1 PDSs demonstrates that the observed integrated power P(sub x), decreases approximately as a square root of the characteristic frequency of the driving oscillations v(sub dr). The RXTE observations of Cyg X-1 allow us to infer P(sub dr), and t(sub o) as a function of v(sub dr). We also apply the basic parameters of observed PDSs, power-law index and low frequency quasiperiodic oscillations. to infer Reynolds (Re) number from the observations using the method developed in our previous paper. Our analysis shows that Re-number increases from values about 10 in low/hard state to that about 70 during the high/soft state. Subject headings: accretion, accretion disks-black hole physics-stars:individual (Cyg X-1) :radiation mechanisms: nonthermal-physical data and processes

  20. Long-Range Chemical Sensitivity in the Sulfur K-Edge X-ray Absorption Spectra of Substituted Thiophenes

    PubMed Central

    2015-01-01

    Thiophenes are the simplest aromatic sulfur-containing compounds and are stable and widespread in fossil fuels. Regulation of sulfur levels in fuels and emissions has become and continues to be ever more stringent as part of governments efforts to address negative environmental impacts of sulfur dioxide. In turn, more effective removal methods are continually being sought. In a chemical sense, thiophenes are somewhat obdurate and hence their removal from fossil fuels poses problems for the industrial chemist. Sulfur K-edge X-ray absorption spectroscopy provides key information on thiophenic components in fuels. Here we present a systematic study of the spectroscopic sensitivity to chemical modifications of the thiophene system. We conclude that while the utility of sulfur K-edge X-ray absorption spectra in understanding the chemical composition of sulfur-containing fossil fuels has already been demonstrated, care must be exercised in interpreting these spectra because the assumption of an invariant spectrum for thiophenic forms may not always be valid. PMID:25116792

  1. Long-range chemical sensitivity in the sulfur K-edge X-ray absorption spectra of substituted thiophenes.

    PubMed

    George, Graham N; Hackett, Mark J; Sansone, Michael; Gorbaty, Martin L; Kelemen, Simon R; Prince, Roger C; Harris, Hugh H; Pickering, Ingrid J

    2014-09-11

    Thiophenes are the simplest aromatic sulfur-containing compounds and are stable and widespread in fossil fuels. Regulation of sulfur levels in fuels and emissions has become and continues to be ever more stringent as part of governments' efforts to address negative environmental impacts of sulfur dioxide. In turn, more effective removal methods are continually being sought. In a chemical sense, thiophenes are somewhat obdurate and hence their removal from fossil fuels poses problems for the industrial chemist. Sulfur K-edge X-ray absorption spectroscopy provides key information on thiophenic components in fuels. Here we present a systematic study of the spectroscopic sensitivity to chemical modifications of the thiophene system. We conclude that while the utility of sulfur K-edge X-ray absorption spectra in understanding the chemical composition of sulfur-containing fossil fuels has already been demonstrated, care must be exercised in interpreting these spectra because the assumption of an invariant spectrum for thiophenic forms may not always be valid. PMID:25116792

  2. Focusing x-ray monochromator for EXAFS studies in the energy range 4-30 keV

    SciTech Connect

    Heald, S.M.

    1983-01-01

    The design and operating principles of a focusing x-ray monochromator are described. Consistent with extended x-ray absorption fine structure (EXAFS) applications it allows rapid tuning while maintaining high energy resolution and a fixed focus at the sample. The basic instrument consists of two opposing two crystal monochromators with the second and third crystals operating as a dispersive monochromator. This provides the intrinsic resolution of the crystals independent of silt settings or source size effects. Focusing is achieved by a sagittally bent fourth crystal. To maintain a fixed focus two options are available. In the first, the second crystal pair is translated while the radius of the fourth crystal is held fixed. Thus, the focus remains at the sample even though the angle of incidence on the bent crystal is changing. In the second option the radius of the bent crystal is changed dynamically as the scan is carried out. These techniques are compared and a crystal bender designed for rapid tuning is described.

  3. X-Ray Astronomy

    NASA Technical Reports Server (NTRS)

    Wu, S. T.

    2000-01-01

    Dr. S. N. Zhang has lead a seven member group (Dr. Yuxin Feng, Mr. XuejunSun, Mr. Yongzhong Chen, Mr. Jun Lin, Mr. Yangsen Yao, and Ms. Xiaoling Zhang). This group has carried out the following activities: continued data analysis from space astrophysical missions CGRO, RXTE, ASCA and Chandra. Significant scientific results have been produced as results of their work. They discovered the three-layered accretion disk structure around black holes in X-ray binaries; their paper on this discovery is to appear in the prestigious Science magazine. They have also developed a new method for energy spectral analysis of black hole X-ray binaries; four papers on this topics were presented at the most recent Atlanta AAS meeting. They have also carried Monte-Carlo simulations of X-ray detectors, in support to the hardware development efforts at Marshall Space Flight Center (MSFC). These computation-intensive simulations have been carried out entirely on the computers at UAH. They have also carried out extensive simulations for astrophysical applications, taking advantage of the Monte-Carlo simulation codes developed previously at MSFC and further improved at UAH for detector simulations. One refereed paper and one contribution to conference proceedings have been resulted from this effort.

  4. Spatial resolution of a hard x-ray CCD detector

    SciTech Connect

    Seely, John F.; Pereira, Nino R.; Weber, Bruce V.; Schumer, Joseph W.; Apruzese, John P.; Hudson, Lawrence T.; Szabo, Csilla I.; Boyer, Craig N.; Skirlo, Scott

    2010-08-10

    The spatial resolution of an x-ray CCD detector was determined from the widths of the tungsten x-ray lines in the spectrum formed by a crystal spectrometer in the 58 to 70 keV energy range. The detector had 20{mu}m pixel, 1700 by 1200 pixel format, and a CsI x-ray conversion scintillator. The spectral lines from a megavolt x-ray generator were focused on the spectrometer's Rowland circle by a curved transmission crystal. The line shapes were Lorentzian with an average width after removal of the natural and instrumental line widths of 95{mu}m (4.75 pixels). A high spatial frequency background, primarily resulting from scattered gamma rays, was removed from the spectral image by Fourier analysis. The spectral lines, having low spatial frequency in the direction perpendicular to the dispersion, were enhanced by partially removing the Lorentzian line shape and by fitting Lorentzian curves to broad unresolved spectral features. This demonstrates the ability to improve the spectral resolution of hard x-ray spectra that are recorded by a CCD detector with well-characterized intrinsic spatial resolution.

  5. Broadband X-Ray Spectral Investigations of Magnetars, 4U 0142+61, 1E 1841-045,1E 2259+586, AND 1E 1048.1-5937

    NASA Astrophysics Data System (ADS)

    Weng, Shan-Shan; G??, Ersin

    2015-12-01

    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.

  6. Spectral and Temporal Properties of the Ultraluminous X-Ray Pulsar in M82 from 15 years of Chandra Observations and Analysis of the Pulsed Emission Using NuSTAR

    NASA Astrophysics Data System (ADS)

    Brightman, Murray; Harrison, Fiona; Walton, Dominic J.; Fuerst, Felix; Hornschemeier, Ann; Zezas, Andreas; Bachetti, Matteo; Grefenstette, Brian; Ptak, Andrew; Tendulkar, Shriharsh; Yukita, Mihoko

    2016-01-01

    The recent discovery by Bachetti et al. of a pulsar in M82 that can reach luminosities of up to 1040 erg s-1, a factor of ˜100 times the Eddington luminosity for a 1.4 M⊙ compact object, poses a challenge for accretion physics. In order to better understand the nature of this source and its duty cycle, and in light of several physical models that have been subsequently published, we conduct a spectral and temporal analysis of the 0.5-8 keV X-ray emission from this source from 15 years of Chandra observations. We analyze 19 ACIS observations where the point-spread function (PSF) of the pulsar is not contaminated by nearby sources. We fit the Chandra spectra of the pulsar with a power-law model and a disk blackbody model, subjected to interstellar absorption in M82. We carefully assess for the effect of pile-up in our observations, where four observations have a pile-up fraction of >10%, which we account for during spectral modeling with a convolution model. When fitted with a power-law model, the average photon index when the source is at high luminosity (LX > 1039 erg s-1) is Γ = 1.33 ± 0.15. For the disk blackbody model, the average temperature is Tin = 3.24 ± 0.65 keV, the spectral shape being consistent with other luminous X-ray pulsars. We also investigated the inclusion of a soft excess component and spectral break, finding that the spectra are also consistent with these features common to luminous X-ray pulsars. In addition, we present spectral analysis from NuSTAR over the 3-50 keV range where we have isolated the pulsed component. We find that the pulsed emission in this band is best fit by a power-law with a high-energy cutoff, where Γ = 0.6 ± 0.3 and {E}{{C}}={14}-3+5 keV. While the pulsar has previously been identified as a transient, we find from our longer-baseline study that it has been remarkably active over the 15-year period, where for 9/19 (47%) observations that we analyzed, the pulsar appears to be emitting at a luminosity in excess of 1039 erg s-1, greater than 10 times its Eddington limit.

  7. Probing Saturation in Stellar Coronae and Chromospheres: Spectral Classification and Analysis of Serendipitously Detected X-ray Sources and Their Optical Counterparts

    NASA Astrophysics Data System (ADS)

    Wolfgang, Angie; Covey, K.; Green, P.

    2009-01-01

    The Chandra Multiwavelength Project (ChaMP) has constructed a database of 6800 X-ray sources serendipitously detected by Chandra imaging and matched to optical counterparts with high confidence. We present new optical spectral classifications for 147 X-ray bright (fX 10-14 - 10-12 ergs s-1) ChaMP sources based primarily on observations with the FAST Spectrograph on the Tillinghast 60" Telescope at Mt. Hopkins. 45 of these sources are identified as M stars with Hα emission and are combined with existing stellar spectra in the ChaMP database, creating a final sample size of 121 emitting M stars which we use to analyze the correlation between LHα/Lbol and LX/Lbol. Analysis by Covey et al. (2008) of 40 M stars in a similar sample found evidence for a turnover in the LHα/Lbol vs. LX/Lbol relationship near LX/ Lbol 3 x 10-4. Our expanded sample nearly triples the size of the sample analyzed by Covey et al. (2008) and shows no evidence of a turnover in the LHα/Lbol vs. LX/Lbol relationship. However, our analysis does corroborate the existence of a plateau at LHα/Lbol 10-3 and suggests a sample bias towards flaring stars. This work is supported in part by the NSF REU and DOD ASSURE programs under NSF grant no. 0754568 and by the Smithsonian Institution.

  8. Phase unwrapping in spectral X-ray differential phase-contrast imaging with an energy-resolving photon-counting pixel detector.

    PubMed

    Epple, Franz M; Ehn, Sebastian; Thibault, Pierre; Koehler, Thomas; Potdevin, Guillaume; Herzen, Julia; Pennicard, David; Graafsma, Heinz; Nol, Peter B; Pfeiffer, Franz

    2015-03-01

    Grating-based differential phase-contrast imaging has proven to be feasible with conventional X-ray sources. The polychromatic spectrum generally limits the performance of the interferometer but benefit can be gained with an energy-sensitive detector. In the presented work, we employ the energy-discrimination capability to correct for phase-wrapping artefacts. We propose to use the phase shifts, which are measured in distinct energy bins, to estimate the optimal phase shift in the sense of maximum likelihood. We demonstrate that our method is able to correct for phase-wrapping artefacts, to improve the contrast-to-noise ratio and to reduce beam hardening due to the modelled energy dependency. The method is evaluated on experimental data which are measured with a laboratory Talbot-Lau interferometer equipped with a conventional polychromatic X-ray source and an energy-sensitive photon-counting pixel detector. Our work shows, that spectral imaging is an important step to move differential phase-contrast imaging closer to pre-clinical and clinical applications, where phase wrapping is particularly problematic. PMID:25163054

  9. Ultra-thin curved transmission crystals for high resolving power (up to E/?E = 6300) x-ray spectroscopy in the 6-13??keV energy range.

    PubMed

    Seely, John F; Hudson, Lawrence T; Glover, Jack L; Henins, Albert; Pereira, Nino

    2014-12-15

    Ultra-thin curved transmission crystals operating in the Cauchois spectrometer geometry were evaluated for the purpose of achieving high spectral resolution in the 6-13 keV x-ray energy range. The crystals were silicon (111) and sapphire R-cut wafers, each 18 ?m thick, and a silicon (100) wafer of 50-?m thickness. The W L?(1) spectral line at 8.398 keV from a laboratory source was used to evaluate the resolution. The highest crystal resolving power, E/?E=6300, was achieved by diffraction from the (33-1) planes of the Si(100) wafer that was cylindrically bent to a radius of curvature of 254 mm, where the (33-1) planes have an asymmetric angle of 13.26 from the normal of the crystal surface facing the x-ray source. This work demonstrates the ability to measure highly resolved line shapes of the K transitions of the elements Fe through Kr and the L transitions of the elements Gd through Th using a relatively compact spectrometer optical system and readily available thin commercial wafers. The intended application is as a diagnostic of laser-produced plasmas where the presence of multiple charged states and broadenings from high temperature and density requires high-resolution methods that are robust in a noisy source environment. PMID:25503010

  10. Mapping of auroral x-rays from rocket overflights

    SciTech Connect

    Goldberg, R.A.; Barcus, J.R.; Treinish, L.A.; Vondrak, R.R.

    1982-04-01

    In March 1978, two Nike Tomahawk payloads were launched from Poker Flat, Alaska, to observe the structure of bremsstrhlung x rays and precipitating particles during both nighttime and daytime observe x rays in four spectral ranges (5--10 keV, 10--20 keV, 20--40 keV, and >40 keV). Particle contamination of the detectors was avoided with broom magnet shielding techniques. By virtue of the payloads' approximate 20/sup 0/ coning angle (about 10.5-s period), the detectors scanned wide regions on either side of the trajectory paths. This has permitted construction (using computer color graphics) of the time averaged (approx.4 min) x ray source regions near 100 km, a height consistent with Chatanika radar electron density maps obtained during each flight period. X ray image maps for both flights exhibit enhanced source regions well outside the rocket trajectory planes. For the nighttime overflight, Chatanika radar scan data and Fort Yukon riometer data were used to verify the presence of an x ray imaged enhancement of electron precipitation, approximately 30 km to the east of the rocket trajectory plane. The daytime x ray data also exhibited several regions of enhanced emission, but outside the region scanned by Chatanika radar. A comparison of the x ray emissions from the two events shows the daytime x ray spectral distributions to be significantly harder but less intense that the nighttime distributions. Furthermore, for both events, spectra compared within and nearby each enhanced emitting region exhibit characteristics of a two component spectrum, such that the bright regions show an increased flux primarily in the low-energy component. Electron fluxes measured on each of the two flights with Geiger tubes are mainly isotropic over the downward hemisphere at night but show anisotropic pitch angle characteristics by day, consistent with the concept that the enhancement of the low-energy x ray flux component is predominantly induced by electrons filling the loss cone.

  11. The ASTRO-H Mission: Unprecedented Spectral Coverage in the X-ray and Soft Gamma-Ray Bands

    NASA Astrophysics Data System (ADS)

    Coppi, Paolo S.; Stawarz, L.; Astro-H Collaboration

    2015-01-01

    Following in the footsteps of the ASCA and Suzaku satellites, the joint Japan-US-European ``ASTRO-H" space mission is considerably more ambitious and represents a major step forward in our ability to study the high-energy universe. Construction of the satellite is well underway, with an anticipated launch date in late 2015. The unprecedented suite of instruments on Astro-H enables simultaneous observations covering 0.1 to 600 keV, including: calorimeter (~5 eV) energy resolution in the 6-7 keV iron line band, good angular resolution and sensitivity, comparable to NuSTAR, at higher energies due to hard X-ray focusing optics, and significant polarization sensitivity above ~50 keV provided by Compton camera electronics. Here we present examples of the spectra expected in a typical 100 kilosecond observation for several classes of sources, focusing on how the combination of Astro-H's instruments enables us to finally break several of the degeneracies that currently hamper modeling efforts for these sources.

  12. Atmospheric electron x-ray spectrometer

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  13. Tokamak x ray diagnostic instrumentation

    SciTech Connect

    Hill, K.W.; Beiersdorfer, P.; Bitter, M.; Fredrickson, E.; Von Goeler, S.; Hsuan, H.; Johnson, L.C.; Liew, S.L.; McGuire, K.; Pare, V.

    1987-01-01

    Three classes of x-ray diagnostic instruments enable measurement of a variety of tokamak physics parameters from different features of the x-ray emission spectrum. (1) The soft x-ray (1 to 50 keV) pulse-height-analysis (PHA) diagnostic measures impurity concentrations from characteristic line intensities and the continuum enhancement, and measures the electron temperature from the continuum slope. (2) The Bragg x-ray crystal spectrometer (XCS) measures the ion temperature and neutral-beam-induced toroidal rotation velocity from the Doppler broadening and wavelength shift, respectively, of spectral lines of medium-Z impurity ions. Impurity charge state distributions, precise wavelengths, and inner-shell excitation and recombination rates can also be studied. X rays are diffracted and focused by a bent crystal onto a position-sensitive detector. The spectral resolving power E/..delta..E is greater than 10/sup 4/ and time resolution is 10 ms. (3) The x-ray imaging system (XIS) measures the spatial structure of rapid fluctuations (0.1 to 100 kHZ) providing information on MHD phenomena, impurity transport rates, toroidal rotation velocity, plasma position, and the electron temperature profile. It uses an array of silicon surface-barrier diodes which view different chords of the plasma through a common slot aperture and operate in current (as opposed to counting) mode. The effectiveness of shields to protect detectors from fusion-neutron radiation effects has been studied both theoretically and experimentally.

  14. X-ray microdiffraction of biominerals.

    PubMed

    Tamura, Nobumichi; Gilbert, Pupa U P A

    2013-01-01

    Biominerals have complex and heterogeneous architectures, hence diffraction experiments with spatial resolutions between 500 nm and 10 ?m are extremely useful to characterize them. X-ray beams in this size range are now routinely produced at many synchrotrons. This chapter provides a review of the different hard X-ray diffraction and scattering techniques, used in conjunction with efficient, state-of-the-art X-ray focusing optics. These include monochromatic X-ray microdiffraction, polychromatic (Laue) X-ray microdiffraction, and microbeam small-angle X-ray scattering. We present some of the most relevant discoveries made in the field of biomineralization using these approaches. PMID:24188780

  15. Measured conversion efficiencies of P45, paraterphenyl, tetraphenyl butadiene, and sodium salicylate phosphors in the soft-x-ray wavelength range

    SciTech Connect

    Regan, S.P.; Huang, L.K.; May, M.J.; Moos, H.W. ); Stutman, D.; Kovnovich, S.; Finkenthal, M. )

    1994-06-01

    The measured conversion efficiencies at 9.89, 23.6, 44.7, and 160 A of P45 phosphor screens, as well as those of paraterphenyl, tetraphenyl butadiene, and sodium salicylate at 9.89, 44.7, and 67.6 A, are presented. The conversion efficiency is defined as the ratio of photoelectrons ejected from the photocathode of a visible detector, which are excited by the scintillated photons that are emitted from the phosphor in a solid angle of 2[pi], to the number of soft-x-ray photons incident on the phosphor. The effect of the phosphor's thickness on the conversion efficiency was studied. The P45 phosphor converts the soft-x-ray photon (10--200 A) into an order of magnitude more visible photons than the low-[ital Z] phosphors. The P45 phosphor screen used in conjunction with a photomultiplier tube offers a soft-x-ray photodetector with a conversion efficiency that ranges from 0.5 at 160 A to 12 at 9.89 A and a high electronic gain.

  16. Absolute calibration of Kodak Biomax-MS film response to x rays in the 1.5- to 8-keV energy range

    NASA Astrophysics Data System (ADS)

    Marshall, F. J.; Knauer, J. P.; Anderson, D.; Schmitt, B. L.

    2006-10-01

    The absolute response of Kodak Biomax-MS film to x rays in the range from 1.5- to 8-keV has been measured using a laboratory electron-beam generated x-ray source. The measurements were taken at specific line energies by using Bragg diffraction to produce monochromatic beams of x rays. Multiple exposures were taken on Biomax MS film up to levels exceeding optical densities of 2 as measured by a microdensitometer. The absolute beam intensity for each exposure was measured with a Si (Li) detector. Additional response measurements were taken with Kodak direct exposure film (DEF) so as to compare the results of this technique to previously published calibrations. The Biomax-MS results have been fitted to a semiempirical mathematical model (Knauer et al., these proceedings). Users of the model can infer absolute fluences from observed exposure levels at either interpolated or extrapolated energies. To summarize the results: Biomax MS has comparable sensitivity to DEF film below 3keV but has reduced sensitivity above 3keV (˜50%). The lower exposure results from thinner emulsion layers, designed for use with phosphor screens. The ease with which Biomax-MS can be used in place of DEF (same format film, same developing process, and comparable sensitivity) makes it a good replacement.

  17. Absolute calibration of Kodak Biomax-MS film response to x rays in the 1.5- to 8-keV energy range

    SciTech Connect

    Marshall, F. J.; Knauer, J. P.; Anderson, D.; Schmitt, B. L

    2006-10-15

    The absolute response of Kodak Biomax-MS film to x rays in the range from 1.5- to 8-keV has been measured using a laboratory electron-beam generated x-ray source. The measurements were taken at specific line energies by using Bragg diffraction to produce monochromatic beams of x rays. Multiple exposures were taken on Biomax MS film up to levels exceeding optical densities of 2 as measured by a microdensitometer. The absolute beam intensity for each exposure was measured with a Si(Li) detector. Additional response measurements were taken with Kodak direct exposure film (DEF) so as to compare the results of this technique to previously published calibrations. The Biomax-MS results have been fitted to a semiempirical mathematical model (Knauer et al., these proceedings). Users of the model can infer absolute fluences from observed exposure levels at either interpolated or extrapolated energies. To summarize the results: Biomax MS has comparable sensitivity to DEF film below 3 keV but has reduced sensitivity above 3 keV ({approx}50%). The lower exposure results from thinner emulsion layers, designed for use with phosphor screens. The ease with which Biomax-MS can be used in place of DEF (same format film, same developing process, and comparable sensitivity) makes it a good replacement.

  18. Small angle X-ray scattering study of carbon nanotube forests densified into long range patterns by controlled solvent evaporation.

    PubMed

    Dume, Ludovic F; Sears, Kallista; Schtz, Jrg A; Finn, Niall; Duke, Mikel; Mudie, Stephen; Kirby, Nigel; Gray, Stephen

    2013-10-01

    Although emergent properties from self-assembly of carbon nanotubes have been described in various forms there is so far no systematic process for the preparation of dense arrays of aligned nanotubes. Here we present a systematic study on the analysis of the alignment of carbon nanotubes within solvent densified carbon nanotube forests. Highly periodic patterns with length scales of the order of the millimetres were generated and characterized by electron and optical micrographs and compared to results from small angle X-ray scattering performed at various incident beam angles. The impact of the different solvents was also discussed in light of the densification process and in relation to solvent properties. PMID:23871309

  19. Short-range order in Fe-based metallic glasses: Wide-angle X-ray scattering studies

    NASA Astrophysics Data System (ADS)

    Babilas, Rafa?; Hawe?ek, ?ukasz; Burian, Andrzej

    2014-11-01

    The local atomic structure of the Fe80B20, Fe70Nb10B20 and Fe62Nb8B30 glasses prepared in the form of ribbons has been studied by wide-angle X-ray scattering. Structural information about the amorphous ribbons has been derived from analysis of the radial distribution functions using the least-squares curve-fitting method. The obtained structural parameters indicate that Fe-Fe, Fe-B, Fe-Nb and Nb-B contributions are involved in the near-neighbor coordination spheres. The possible similarities of the local atomic arrangement in the investigated glasses and the crystalline Fe3B, Fe23B6 and bcc Fe structures are also discussed.

  20. Structural information from multilamellar liposomes at full hydration: Full q-range fitting with high quality x-ray data

    NASA Astrophysics Data System (ADS)

    Pabst, Georg; Rappolt, Michael; Amenitsch, Heinz; Laggner, Peter

    2000-09-01

    We present a method for analyzing small angle x-ray scattering data on multilamellar phospholipid bilayer systems at full hydration. The method utilizes a modified Caill theory structure factor in combination with a Gaussian model representation of the electron density profile such that it accounts also for the diffuse scattering between Bragg peaks. Thus the method can retrieve structural information even if only a few orders of diffraction are observed. We further introduce a procedure to derive fundamental parameters, such as area per lipid, membrane thickness, and number of water molecules per lipid, directly from the electron density profile without the need of additional volumetric measurements. The theoretical apparatus is applied to experimental data on 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine liposome preparations.

  1. The Chandra X-ray Observatory: An Astronomical Facility Available to the World

    NASA Technical Reports Server (NTRS)

    Smith, Randall K.

    2006-01-01

    The Chandra X-ray observatory, one of NASA's "Great Observatories," provides high angular and spectral resolution X-ray data which is freely available to all. In this review I describe the instruments on chandra along with their current calibration, as well as the chandra proposal system, the freely-available Chandra analysis software package CIAO, and the Chandra archive. As Chandra is in its 6th year of operation, the archive already contains calibrated observations of a large range of X-ray sources. The Chandra X-ray Center is committed to assisting astronomers from any country who wish to use data from the archive or propose for observations

  2. Investigation of the polynomial approach for material decomposition in spectral X-ray tomography using an energy-resolved detector

    NASA Astrophysics Data System (ADS)

    Potop, A.; Rebuffel, V.; Rinkel, J.; Brambilla, A.; Peyrin, F.; Verger, L.

    2014-03-01

    Recent advances in the domain of energy-resolved semiconductor detectors stimulate research in X-ray computed tomography (CT). However, the imperfections of these detectors induce errors that should be considered for further applications. Charge sharing and pile-up effects due to high photon fluxes can degrade image quality or yield wrong material identification. Basis component decomposition provides separate images of principal components, based on the energy related information acquired in each energy bin. The object is typically either decomposed in photoelectric and Compton physical effects or in basis materials functions. This work presents a simulation study taking into account the properties of an energy-resolved CdTe detector with flexible energy thresholds in the context of materials decomposition CT. We consider the effects of a first order pile-up model with triangular pulses of a non-paralyzable detector and a realistic response matrix. We address the problem of quantifying mineral content in bone based on a polynomial approach for material decomposition in the case of two and three energy bins. The basis component line integrals are parameterized directly in the projection domain and a conventional filtered back-projection reconstruction is performed to obtain the material component images. We use figures of merit such as noise and bias to select the optimal thresholds and quantify the mineral content in bone. The results obtained with an energy resolved detector for two and three energy bins are compared with the ones obtained for the dual-kVp technique using an integrating-mode detector with filters and voltages optimized for bone densitometry.

  3. Effect of hydration on the long-range order of lipid multilayers investigated by in situ time-resolved energy dispersive X-ray diffraction

    NASA Astrophysics Data System (ADS)

    Caminiti, Ruggero; Caracciolo, Giulio; Pisani, Michela; Bruni, Paolo

    2005-06-01

    In situ time-resolved energy dispersive X-ray diffraction (EDXD) was applied to investigate the hydration kinetics of oriented dioleoylphosphocoline (DOPC) and 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) membranes. The long-range order in the investigated lipid multilayers has been found to vary as a function of hydration in a nonmonotic way. In the first stage, water adsorption increased the long-range order along the normal to the lipid bilayer whereas, in the second one, a progressive loss of interbilayer coherence was observed. Possible molecular mechanisms underlying the experimental observations are discussed.

  4. Chest x-ray

    MedlinePLUS

    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 first ...

  5. Multilayer Coatings for UV Spectral Range

    NASA Astrophysics Data System (ADS)

    Miloushev, Ilko; Tenev, Tihomir; Peyeva, Rumiana; Panajotov, Krassimir

    2010-01-01

    Optical coatings for the UV spectral range play currently a significant role in the modern optical devices. For reducing of manufacturing cost the reliable design is essential. Therefore, better understanding of the optical properties of the used materials is indispensable for the proper design and manufacturing of the multilayer UV coatings. In this work we present some results on the preparation of reflective UV coatings. The implemented materials are magnesium fluoride and lanthanum fluoride. Their optical constants are determined from spectral characteristics of single layers in the 200-800 nm spectral range, obtained by thermal boat evaporation in high vacuum conditions. These results are subsequently used for the analysis of high reflection (HR) stack made of 40 layers deposited by the same deposition process.

  6. X-ray Lines in Stellar Coronae

    NASA Astrophysics Data System (ADS)

    Mewe, R.

    Because the emission line spectra and continua from optically thin plasmas are fairly well known, high-resolution X-ray spectroscopy has its most obvious application in the measurement of optically thin sources such as the coronae of stars. In particular X-ray observations with the EINSTEIN observatory have demonstrated that soft X-ray emitting coronae are a common feature among stars on the cool side of the Hertzsprung-Russell diagram, with the probable exception of single very cool giant and supergiant stars and A-type dwarfs. Observations with the spectrometers aboard EINSTEIN and EXOSAT have shown that data of even modest spectral resolution (/= 10-100 permit the identification of coronal material at different temperatures whose existence may relate to a range of possible magnetic loop structures in the outer atmospheres of these stars. The improved spectral resolution of the next generation of spectrometers aboard XMM and AXAF is needed to fully resolve the temperature structure of stellar coronae and to enable density and velocity diagnostics. In this paper spectral results from EINSTEIN and EXOSAT are discussed. A few simulations of high-resolution re L, K, and 2s-2p spectra with AXAF, XMM, and several detectors such as calorimeter and Nb-junction are shown to demonstrate the capabilities for plasma diagnostics.

  7. A longer XMM-Newton look at I Zwicky - 1. Distinct modes of X-ray spectral variability

    NASA Astrophysics Data System (ADS)

    Gallo, L. C.; Brandt, W. N.; Costantini, E.; Fabian, A. C.

    2007-05-01

    The short-term spectral variability of the narrow-line Seyfert 1 galaxy I Zwicky 1 (I Zw 1) as observed in an 85ks XMM-Newton observation is discussed in detail. I Zw 1 shows distinct modes of variability prior to and after a flux dip in the broad-band light curve. Before the dip the variability can be described as arising from changes in shape and normalization of the spectral components. Only changes in normalization are manifested after the dip. The change in the mode of behaviour occurs on dynamically short time-scales in I Zw 1. The data suggest that the accretion-disc corona in I Zw 1 could have two components that are co-existing. The first, a uniform, physically diffuse plasma responsible for the `typical' long-term (e.g. years) behaviour; and a second compact, centrally located component causing the rapid flux and spectral changes. This compact component could be the base of a short or aborted jet as sometimes proposed for radio-quiet active galaxies. Modelling of the average and time-resolved rms spectra demonstrate that a blurred Compton-reflection model can describe the spectral variability if we allow for pivoting of the continuum component prior to the dip.

  8. Laser plasma x-ray source for ultrafast time-resolved x-ray absorption spectroscopy

    PubMed Central

    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.

    2015-01-01

    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??m 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. PMID:26798792

  9. Comparative evaluation of single crystal scintillators under x-ray imaging conditions

    NASA Astrophysics Data System (ADS)

    Valais, I. G.; David, S.; Michail, C.; Nomicos, C. D.; Panayiotakis, G. S.; Kandarakis, I. S.

    2009-06-01

    The present study is a comparative investigation of the luminescence properties of (Lu,Y)2SiO5: Ce (LYSO: Ce), YAlO3: Ce (YAP: Ce), Gd2SiO5: Ce (GSO: Ce) and (Bi4Ge3O12) BGO single crystal scintillators under x-ray excitation. Results will be of value in designing dual modality tomographic systems (PET/CT, SPECT/CT) based on a common scintillator crystal. All scintillating crystals have dimensions of 10 10 10 cm3 are non-hygroscopic exhibiting high radiation absorption efficiency in the energy range used in medical imaging applications. The comparative investigation was performed by determining the x-ray luminescence efficiency (emitted light flux over incident x-ray energy flux) in the range of x-ray energies employed in: (i) general x-ray imaging (40-140 kV, using a W/Al x-ray spectrum) and (ii) x-ray mammography imaging (22-49 kV, using a Mo/Mo x-ray spectrum). Additionally, light emission spectra of crystals at various x-ray energies were measured, in order to determine the intrinsic conversion efficiency and the spectral compatibility to optical photon detectors incorporated in medical imaging systems. The light emission performance of LYSO:Ce scintillator studied was found very high for x-ray imaging.

  10. X ray imaging microscope for cancer research

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.; Shealy, David L.; Brinkley, B. R.; Baker, Phillip C.; Barbee, Troy W., Jr.; Walker, Arthur B. C., Jr.

    1991-01-01

    The NASA technology employed during the Stanford MSFC LLNL Rocket X Ray Spectroheliograph flight established that doubly reflecting, normal incidence multilayer optics can be designed, fabricated, and used for high resolution x ray imaging of the Sun. Technology developed as part of the MSFC X Ray Microscope program, showed that high quality, high resolution multilayer x ray imaging microscopes are feasible. Using technology developed at Stanford University and at the DOE Lawrence Livermore National Laboratory (LLNL), Troy W. Barbee, Jr. has fabricated multilayer coatings with near theoretical reflectivities and perfect bandpass matching for a new rocket borne solar observatory, the Multi-Spectral Solar Telescope Array (MSSTA). Advanced Flow Polishing has provided multilayer mirror substrates with sub-angstrom (rms) smoothnesss for the astronomical x ray telescopes and x ray microscopes. The combination of these important technological advancements has paved the way for the development of a Water Window Imaging X Ray Microscope for cancer research.

  11. An evaluation of multilayer mirrors for the soft x ray and extreme ultraviolet wavelength range that were irradiated with neutrons

    NASA Astrophysics Data System (ADS)

    Regan, S. P.; May, M. J.; Soukhanovskii, V.; Finkenthal, M.; Moos, H. W.; Farnum, E. H.; Clinard, F. W., Jr.; Tarrio, C.; Watts, R.

    1997-01-01

    The Plasma Spectroscopy Group at the Johns Hopkins University develops high photon throughput multilayer mirror (MLM) based soft x ray and extreme ultraviolet (XUV 10 Å<λ<304 Å) spectroscopic diagnostics for magnetically confined fusion plasmas. The D-T reactions in large fusion reactor type devices such as the International Thermonuclear Experimental Reactor will produce neutrons at a rate as high as 5×1019 n s-1. The MLMs, which are used as dispersive and focusing optics, will not be shielded from these neutrons. In an effort to assess the potential radiation damage, four MLMs (No. 1: Mo/Si, d=87.8 Å, Zerodur substrate with 50 cm concave spherical curvature; No. 2: W/B4C, d=22.75 Å, Si wafer substrate; No. 3: W/C, d=25.3 Å, Si wafer substrate; and No. 4: Mo/Si, d=186.6 Å, Si wafer substrate) were irradiated with fast neutrons at the Los Alamos Spallation Radiation Effects Facility (LASREF). The neutron beam at LASREF has an energy distribution that peaks at 1-2 MeV with a tail that extends out to 100 MeV. The MLMs were irradiated to a fast neutron fluence of 1.1×1019 n cm-2 at 270-300 °C. A comparison between the dispersive and reflective characteristics of the irradiated MLMs and the corresponding qualities of control samples will be given.

  12. X-Ray Vision

    NASA Technical Reports Server (NTRS)

    Ramsey, B. D.; Elsner, R. F.; Engelhaupt, D.; Kolodziejczak, J. J.; ODell, S. L.; Speegle, C. O.; Weisskopf, M. C.

    2004-01-01

    We are fabricating optics for the hard-x-ray region using electroless nickel replication. The attraction of this process, which has been widely used elsewhere, is that the resulting full shell optics are inherently stable and thus can have very good angular resolution. The challenge with this process is to develop lightweight optics (nickel has a relatively high density of 8.9 g/cu cm), and to keep down the costs of mandrel fabrication. We accomplished the former through the development of high-strength nickel alloys that permit very thin shells without fabrication- and handling-induced deformations. For the latter, we have utilized inexpensive grinding and diamond turning to figure the mandrels and then purpose-built polishing machines to finish the surface. In-house plating tanks and a simple water-bath separation system complete the process. To date we have built shells ranging in size from 5 cm diameter to 50 cm, and with thickness down to 100 micron. For our HERO balloon program, we are fabricating over 200 iridium-coated shells, 250 microns thick, for hard-x-ray imaging up to 75 keV. Early test results on these have indicated half-power-diameters of 15 arcsec. The status of these and other hard-x-ray optics will be reviewed.

  13. The feasibility of independent observations/detections of GRBs in X-rays

    SciTech Connect

    Hudec, R.; Skulinova, M.; Pina, L.; Sveda, L.; Semencova, V.; Inneman, A.

    2009-05-25

    According to the observational statistics a large majority of all GRBs exhibit X-ray emission. In addition, a dedicated separate group of GRB, the XRFs, exists which emission dominates in the X-ray spectral range. And the third group of GRB related objects (yet hypothetical) are the group of off-axis observed GRBs (orphan afterglows). These facts justify the consideration of an independent experiment for monitoring, detection and analyses of GRBs and others fast X-ray transients in X-rays. We will present and discuss such experiment based on wide-field X-ray telescopes of Lobster Eye type. The wide field and fine sensitivity of Lobster Eye X-ray All-Sky Monitor make such instruments important tools in study of GRBs and related objects.

  14. The feasibility of independent observations/detections of GRBs in X-rays

    NASA Astrophysics Data System (ADS)

    Hudec, R.; Pina, L.; Marsikova, V.; Inneman, A.; Skulinova, M.

    2011-08-01

    According to the observational statistics a large majority of all GRBs exhibit X-ray emission. In addition, a dedicated separate group of GRB, the XRFs, exists which emission dominates in the X-ray spectral range. And the third group of GRB related objects (yet hypothetical) are the group of off-axis observed GRBs (orphan afterglows). These facts justify the consideration of an independent experiment for monitoring, detection and analyses of GRBs and others fast X-ray transients in X-rays. We will present and discuss such experiment based on wide-field X-ray telescopes of Lobster Eye type. The wide field and fine sensitivity of Lobster Eye X-ray All-Sky Monitor make such instruments important tools in study of GRBs and related objects.

  15. Stimulated Electronic X-Ray Raman Scattering

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  16. Long-range structure of Cu(InxGa1-x)3Se5: A complementary neutron and anomalous x-ray diffraction study

    NASA Astrophysics Data System (ADS)

    Lehmann, S.; Marrn, D. frtes; Len, M.; Feyerherm, R.; Dudzik, E.; Friedrich, E. J.; Tovar, M.; Tomm, Y.; Wolf, C.; Schorr, S.; Schedel-Niedrig, Th.; Lux-Steiner, M. Ch.; Merino, J. M.

    2011-01-01

    Distinguishing the scattering contributions of isoelectronic atomic species by means of conventional x-ray- and/or electron diffraction techniques is a difficult task. Such a problem occurs when determining the crystal structure of compounds containing different types of atoms with equal number of electrons. We propose a new structural model of Cu(InxGa1-x)3Se5 which is valid for the entire compositional range of the CuIn3Se5-CuGa3Se5 solid solution. Our model is based on neutron and anomalous x-ray diffraction experiments. These complementary techniques allow the separation of scattering contributions of the isoelectronic species Cu+ and Ga3+, contributing nearly identically in monoenergetic x-ray diffraction experiments. We have found that CuIII3Se5 (III=In,Ga) in its room temperature near-equilibrium modification exhibits a modified stannite structure (space group I42m). Different occupation factors of the species involved, Cu+, In3+, Ga3+, and vacancies have been found at three different cationic positions of the structure (Wyckoff sites 2a, 2b, and 4d) depending on the composition of the compound. Significantly, Cu+ does not occupy the 2b site for the In-free compound, but does for the In-containing case. Structural parameters, including lattice constants, tetragonal distortions, and occupation factors are given for samples covering the entire range of the CuIn3Se5-CuGa3Se5 solid solution. At the light of the result, the denotation of Cu-poor 1:3:5 compounds as chalcopyrite-related materials is only valid in reference to their composition.

  17. On the Nature of the Variability Power Decay toward Soft Spectral States in X-Ray Binaries: Case Study in Cygnus X-1

    NASA Astrophysics Data System (ADS)

    Titarchuk, Lev; Shaposhnikov, Nikolai

    2008-05-01

    A characteristic feature of the Fourier power density spectrum (PDS) observed from black hole X-ray binaries in low/hard and intermediate spectral states is a broadband-limited noise characterized by a constant below some frequency (a "break" frequency) and a power law above this frequency. It has been shown that the variability of this type can be produced by the inward diffusion of the local driving perturbations in a bounded configuration (accretion disk or corona). In the framework of this model, the perturbation diffusion time t0 is related to the phenomenological break frequency, while the PDS power-law slope above the "break" is determined by the viscosity distribution over the configuration. The perturbation diffusion scenario explains the decay of the power of X-ray variability observed in a number of compact sources (containing black holes and neutron stars) during an evolution of these sources from low/hard to high/soft states. We compare the model predictions with the subset of data from Cyg X-1 collected by the Rossi X-Ray Time Explorer (RXTE). Our extensive analysis of the Cyg X-1 PDSs demonstrates that the observed integrated power Px decreases approximately as the square root of the characteristic frequency of the driving oscillations ?dr. The RXTE observations of Cyg X-1 allow us to infer Pdr and t0 as a function of ?dr. Using the inferred dependences of the integrated power of the driving oscillations Pdr and t0 on ?dr we demonstrate that the power predicted by the model also decays as Px,diff propto ??0.5dr, which is similar to the observed Px behavior. We also apply the basic parameters of observed PDSs, power-law indices, and low-frequency quasi-periodic oscillations to infer the Reynolds number (Re) from the observations using the method developed in our previous paper. Our analysis shows that Re increases from values of about 10 in low/hard state to about 70 during the high/soft state.

  18. On the nature of the variability power decay towards soft spectral states in X-ray binaries. Case study in Cyg X-1

    NASA Astrophysics Data System (ADS)

    Titarchuk, Lev; Shaposhnikov, Nikolai

    2008-01-01

    A characteristic feature of the Fourier Power Density Spectrum (PDS) observed from black hole X-ray binaries in low/hard and intermediate spectral states is a broad band-limited noise, characterized by a constant below some frequency (a ``break'' frequency) and a power law above this frequency. It has been shown that the variability of this type can be produced by the inward diffusion of the local driving perturbations in a bounded configuration (accretion disk or corona). In the framework of this model, the perturbation diffusion time t0 is related to the phenomenological break frequency, while the PDS power-law slope above the ``break'' is determined by the viscosity distribution over the configuration. The perturbation diffusion scenario explains the decay of the power of X-ray variability observed in a number of compact sources (containing black hole and neutron star) during an evolution of theses sources from low/hard to high/soft states. We compare the model predictions with the subset of data from Cyg X-1 collected by the Rossi X-ray Time Explorer (RXTE). Our extensive analysis of the Cyg X-1 PDSs demonstrates that the observed integrated power Px decreases approximately as a square root of the characteristic frequency of the driving oscillations ?dr. The RXTE observations of Cyg X-1 allow us to infer Pdr and t0 as a function of ?dr. Using the inferred dependences of the integrated power of the driving oscillations Pdr and t0 on ?dr we demonstrate that the power predicted by the model also decays as Px,diff~?dr-0.5 that is similar to the observed Px behavior. We also apply the basic parameters of observed PDSs, power-law index and low frequency quasiperiodic oscillations, to infer Reynolds (Re) number from the observations using the method developed in our previous paper. Our analysis shows that Re-number increases from values about 10 in low/hard state to that about 70 during the high/soft state.

  19. Warm Absorbers in X-rays (WAX), a comprehensive high resolution grating spectral study of a sample of Seyfert Galaxies: II. Warm Absorber dynamics and feedback to galaxies.

    NASA Astrophysics Data System (ADS)

    Laha, Sibasish; Guainazzi, Matteo; Chakravorty, Susmita; Dewangan, Gulab C.; Kembhavi, Ajit K.

    2016-02-01

    This paper is a sequel to the extensive study of warm absorber (WA) in X-rays carried out using high resolution grating spectral data from XMM-Newton satellite (WAX-I). Here we discuss the global dynamical properties as well as the energetics of the WA components detected in the WAX sample. The slope of WA density profile (n?r-?) estimated from the linear regression slope of ionization parameter ? and column density NH in the WAX sample is ? = 1.236 0.034. We find that the WA clouds possibly originate as a result of photo-ionised evaporation from the inner edge of the torus (torus wind). They can also originate in the cooling front of the shock generated by faster accretion disk outflows, the ultra-fast outflows (UFO), impinging onto the interstellar medium or the torus. The acceleration mechanism for the WA is complex and neither radiatively driven wind nor MHD driven wind scenario alone can describe the outflow acceleration. However, we find that radiative forces play a significant role in accelerating the WA through the soft X-ray absorption lines, and also with dust opacity. Given the large uncertainties in the distance and volume filling factor estimates of the WA, we conclude that the kinetic luminosity ?K of WA may sometimes be large enough to yield significant feedback to the host galaxy. We find that the lowest ionisation states carry the maximum mass outflow, and the sources with higher Fe M UTA absorption (15-17 ) have more mass outflow rates.

  20. Application of the new comprehensive X-ray spectral model to the two brightest intermediate polars EX Hydrae and V1223 Sagittarii

    NASA Astrophysics Data System (ADS)

    Hayashi, Takayuki; Ishida, Manabu

    2014-07-01

    We applied the new comprehensive X-ray spectral model for the post-shock accretion column (PSAC) of the intermediate polars (IPs) constructed by Hayashi and Ishida to the Suzaku data of the two brightest IPs EX Hydrae and V1223 Sagittarii. The white dwarf (WD) mass and the specific accretion rate of EX Hya are estimated to be M_WD= 0.63_{-0.14}^{+0.17} M? and a=0.049_{-0.035}^{+0.66} g cm-2 s-1. Our WD mass of EX Hya is greater than that of previous X-ray estimations (0.4-0.5 M?), where higher specific accretion rate than ours is assumed, and marginally consistent with 0.790 0.026 M? measured by Beuermann and Reinsch using a binary motion. On the other hand, with the aid of the PSAC height of V1223 Sgr hV1223 < 0.07RWD, we estimated M_WD= 0.87_{-0.06}^{+0.10} M_{?} and a > 2.0 g cm-2 s-1 for V1223 Sgr. We evaluated the fractional accreting area of EX Hya and V1223 Sgr at 0.0033_{-0.0030}^{+0.0067} and <0.007, respectively. Calculation of the hydrodynamical equations with these best-fitting parameters show that the PSAC height of EX Hya is 0.33 RWD = 2.8 108 cm. The maximum temperature of the EX Hya and V1223 Sgr are calculated at 18.0 keV and 43.1 keV, respectively. In EX Hya, the temperature distribution is flatter and the density at the top of the PSAC is smaller than those of the previous PSAC models because of its low specific accretion rate.

  1. Syntheses, spectral characterization, X-ray studies and in vitro cytotoxic activities of triorganotin(IV) derivatives of p-substituted N-methylbenzylaminedithiocarbamates

    NASA Astrophysics Data System (ADS)

    Khan, Naqeebullah; Farina, Yang; Mun, Lo Kong; Rajab, Nor Fadilah; Awang, Normah

    2014-11-01

    Two new organotin(IV) complexes of the type R3SnL, where (L = p-bromo-N-methylbenzylaminedithiocarbamate and p-fluoro-N-methylbenzylaminedithiocarbamate, and R = phenyl) have been synthesized in 1:1 molar ratio with good yields and isolated as crystalline solids. The newly synthesized compounds gave fairly sharp melting points indicating that the compounds were pure. A systematic investigation of the derivatives were carried out both in solid and in solution and were suitably characterized by elemental analysis, FT-IR, 1H, 13C, 119Sn NMR spectroscopies. The dithiocarbamate ligands chelated to the tin metal monodentately using only one sulfur atom showing a pair of bands due to ?(Cdbnd S) below 1000 cm-1. This phenomenon was supported by the occurrence of new medium to weak absorptions in the region 411-545, in the spectra of complexes, assigned to ?(Snsbnd S) and ?(Snsbnd C). The crystal structures of the two triorganotin(IV) complexes have been determined by X-ray crystallography. Both the complexes crystallized in the monoclinic, P2(1)/n space group. The spectral investigations and single crystal X-ray diffraction data illustrate that the two dithiocarbamato ligands in the triphenyltin(IV) derivatives 1 and 2 are monodentate and the geometry at tin is best described as a distorted tetrahedron. The in vitro antiproliferative tests of these two derivatives on three human cell lines, leukemic lymphoblastoma Jurkat cells, lymphoblastoma K-562 cells, hepatoblastoma HepG2 cells and one mouse fibroblast cells L929 show dose-dependent decrease of cell proliferation in all cell lines.

  2. An evaluation of multilayer mirrors for the soft x ray and extreme ultraviolet wavelength range that were irradiated with neutrons

    SciTech Connect

    Regan, S.P.; May, M.J.; Soukhanovskii, V.; Finkenthal, M.; Moos, H.W.; Farnum, E.H.; Clinard, F.W. Jr.; Tarrio, C.; Watts, R.

    1997-01-01

    The Plasma Spectroscopy Group at the Johns Hopkins University develops high photon throughput multilayer mirror (MLM) based soft x ray and extreme ultraviolet (XUV 10 {Angstrom}{lt}{lambda}{lt}304 {Angstrom}) spectroscopic diagnostics for magnetically confined fusion plasmas. The D-T reactions in large fusion reactor type devices such as the International Thermonuclear Experimental Reactor will produce neutrons at a rate as high as 5{times}10{sup 19} ns{sup -1}. The MLMs, which are used as dispersive and focusing optics, will not be shielded from these neutrons. In an effort to assess the potential radiation damage, four MLMs (No. 1: Mo/Si, d=87.8 {Angstrom}, Zerodur substrate with 50 cm concave spherical curvature; No. 2: W/B{sub 4}C, d=22.75 {Angstrom}, Si wafer substrate; No. 3: W/C, d=25.3 {Angstrom}, Si wafer substrate; and No. 4: Mo/Si, d=186.6 {Angstrom}, Si wafer substrate) were irradiated with fast neutrons at the Los Alamos Spallation Radiation Effects Facility (LASREF). The neutron beam at LASREF has an energy distribution that peaks at 1{endash}2 MeV with a tail that extends out to 100 MeV. The MLMs were irradiated to a fast neutron fluence of 1.1{times}10{sup 19} ncm{sup {minus}2} at 270{endash}300{degree}C. A comparison between the dispersive and reflective characteristics of the irradiated MLMs and the corresponding qualities of control samples will be given. {copyright} {ital 1997 American Institute of Physics.}

  3. X-ray astronomical spectroscopy

    NASA Technical Reports Server (NTRS)

    Holt, S. S.

    1980-01-01

    The current status of the X-ray spectroscopy of celestial X-ray sources, ranging from nearby stars to distant quasars, is reviewed. Particular emphasis is placed on the role of such spectroscopy as a useful and unique tool in the elucidation of the physical parameters of the sources. The spectroscopic analysis of degenerate and nondegenerate stellar systems, galactic clusters and active galactic nuclei, and supernova remnants is discussed.

  4. Monolithic CMOS imaging x-ray spectrometers

    NASA Astrophysics Data System (ADS)

    Kenter, Almus; Kraft, Ralph; Gauron, Thomas; Murray, Stephen S.

    2014-07-01

    The Smithsonian Astrophysical Observatory (SAO) in collaboration with SRI/Sarnoff is developing monolithic CMOS detectors optimized for x-ray astronomy. The goal of this multi-year program is to produce CMOS x-ray imaging spectrometers that are Fano noise limited over the 0.1-10keV energy band while incorporating the many benefits of CMOS technology. These benefits include: low power consumption, radiation "hardness", high levels of integration, and very high read rates. Small format test devices from a previous wafer fabrication run (2011-2012) have recently been back-thinned and tested for response below 1keV. These devices perform as expected in regards to dark current, read noise, spectral response and Quantum Efficiency (QE). We demonstrate that running these devices at rates ~> 1Mpix/second eliminates the need for cooling as shot noise from any dark current is greatly mitigated. The test devices were fabricated on 15μm, high resistivity custom (~30kΩ-cm) epitaxial silicon and have a 16 by 192 pixel format. They incorporate 16μm pitch, 6 Transistor Pinned Photo Diode (6TPPD) pixels which have ~40μV/electron sensitivity and a highly parallel analog CDS signal chain. Newer, improved, lower noise detectors have just been fabricated (October 2013). These new detectors are fabricated on 9μm epitaxial silicon and have a 1k by 1k format. They incorporate similar 16μm pitch, 6TPPD pixels but have ~ 50% higher sensitivity and much (3×) lower read noise. These new detectors have undergone preliminary testing for functionality in Front Illuminated (FI) form and are presently being prepared for back thinning and packaging. Monolithic CMOS devices such as these, would be ideal candidate detectors for the focal planes of Solar, planetary and other space-borne x-ray astronomy missions. The high through-put, low noise and excellent low energy response, provide high dynamic range and good time resolution; bright, time varying x-ray features could be temporally and spectrally resolved without saturation. We present details of our camera design and device performance with particular emphasis on those aspects of interest to single photon counting x-ray astronomy. These features include read noise, x-ray spectral response and quantum efficiency. Funding for this work has been provided in large part by NASA Grant NNX09AE86G and a grant from the Betty and Gordon Moore Foundation.

  5. X ray spectra of cataclysmic variables

    NASA Technical Reports Server (NTRS)

    Patterson, Joseph; Halpern, Jules

    1990-01-01

    X ray spectral parameters of cataclysmic variables observed with the 'Einstein' imaging proportional counter were determined by fitting an optically thin, thermal bremsstrahlung spectrum to the raw data. Most of the sources show temperatures of order a few keV, while a few sources exhibit harder spectra with temperatures in excess of 10 keV. Estimated 0.1 to 3.5 keV luminosities are generally in the range from 10(exp 30) to 10(exp 32) erg/sec. The results are consistent with the x rays originating in a disk/white dwarf boundary layer of non-magnetic systems, or in a hot, post-shock region in the accretion column of DQ Her stars, with a negligible contribution from the corona of the companion. In a few objects column densities were found that are unusually high for interstellar material. It was suggested that the absorption occurs in the system itself.

  6. EUV spectroscopy of high-redshift x-ray objects

    NASA Astrophysics Data System (ADS)

    Kowalski, M. P.; Wolff, M. T.; Wood, K. S.; Barbee, T. W., Jr.; Barstow, M. A.

    2010-07-01

    As astronomical observations are pushed to cosmological distances (z>3) the spectral energy distributions of X-ray objects, AGN for example, will be redshifted into the EUV waveband. Consequently, a wealth of critical spectral diagnostics, provided by, for example, the Fe L-shell complex and the O VII/VIII lines, will be lost to future planned X-ray missions (e.g., IXO, Gen-X) if operated at traditional X-ray energies. This opens up a critical gap in performance located at short EUV wavelengths, where critical X-ray spectral transitions occur in high-z objects. However, normal-incidence multilayer-grating technology, which performs best precisely at such wavelengths, together with advanced nanolaminate replication techniques have been developed and are now mature to the point where advanced EUV instrument designs with performance complementary to IXO and Gen-X are practical. Such EUV instruments could be flown either independently or as secondary instruments on these X-ray missions. We present here a critical examination of the limits placed on extragalactic EUV measurements by ISM absorption, the range where high-z measurements are practical, and the requirements this imposes on next-generation instrument designs. We conclude with a discussion of a breakthrough technology, nanolaminate replication, which enables such instruments.

  7. A novel flat-response x-ray detector in the photon energy range of 0.1-4 keV

    NASA Astrophysics Data System (ADS)

    Li, Zhichao; Jiang, Xiaohua; Liu, Shenye; Huang, Tianxuan; Zheng, Jian; Yang, Jiamin; Li, Sanwei; Guo, Liang; Zhao, Xuefeng; Du, Huabin; Song, Tianming; Yi, Rongqing; Liu, Yonggang; Jiang, Shaoen; Ding, Yongkun

    2010-07-01

    A novel flat-response x-ray detector has been developed for the measurement of radiation flux from a hohlraum. In order to obtain a flat response in the photon energy range of 0.1-4 keV, it is found that both the cathode and the filter of the detector can be made of gold. A further improvement on the compound filter can then largely relax the requirement of the calibration x-ray beam. The calibration of the detector, which is carried out on Beijing Synchrotron Radiation Facility at Institute of High Energy Physics, shows that the detector has a desired flat response in the photon energy range of 0.1-4 keV, with a response flatness smaller than 13%. The detector has been successfully applied in the hohlraum experiment on Shenguang-III prototype laser facility. The radiat