WorldWideScience

Sample records for anomalous x-ray pulsars

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

    Science.gov (United States)

    Guo, Yan-Jun; Dai, Shi; Li, Zhao-Sheng; Liu, Yuan; Tong, Hao; Xu, Ren-Xin

    2015-04-01

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

  2. Discovery of Hard Nonthermal Pulsed X-Ray Emission from the Anomalous X-Ray Pulsar 1E 1841-045

    NARCIS (Netherlands)

    Kuiper, L.; Hermsen, W.; Méndez, R.M.

    2004-01-01

    We report the discovery of nonthermal pulsed X-ray/soft gamma-ray emission up to ~150 keV from the anomalous 11.8 s X-ray pulsar AXP 1E 1841-045 located near the center of supernova remnant Kes 73 using Rossi X-Ray Timing Explorer (RXTE) Proportional Counter Array and High Energy X-Ray Timing

  3. ON THE EVOLUTION OF ANOMALOUS X-RAY PULSARS AND SOFT GAMMA-RAY REPEATERS WITH FALL BACK DISKS

    International Nuclear Information System (INIS)

    Ertan, Ue.; Alpar, M. A.; Eksi, K. Y.; Erkut, M. H.

    2009-01-01

    We show that the period clustering of anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs), their X-ray luminosities, ages, and statistics can be explained with fall back disks with large initial specific angular momentum. The disk evolution models are developed by comparison to self-similar analytical models. The initial disk mass and angular momentum set the viscous timescale. An efficient torque, with (1 - ω 2 * ) dependence on the fastness parameter ω * , leads to period clustering in the observed AXP-SGR period range under a wide range of initial conditions. The timescale t 0 for the early evolution of the fall back disk, and the final stages of fall back disk evolution, when the disk becomes passive, are the crucial determinants of the evolution. The disk becomes passive at temperatures around 100 K, which provides a natural cutoff for the X-ray luminosity and defines the end of evolution in the observable AXP and SGR phase. This low value for the minimum temperature for active disk turbulence indicates that the fall back disks are active up to a large radius, ∼>10 12 cm. We find that transient AXPs and SGRs are likely to be older than their persistent cousins. A fall back disk with mass transfer rates corresponding to the low quiescent X-ray luminosities of the transient sources in early evolutionary phases would have a relatively lower initial mass, such that the mass-flow rate in the disk is not sufficient for the inner disk to penetrate into the light cylinder of the young neutron star, making mass accretion onto the neutron star impossible. The transient AXP phase therefore must start later. The model results imply that the transient AXP/SGRs, although older, are likely to be similar in number to persistent sources. This is because the X-ray luminosities of AXPs and SGRs are found to decrease faster at the end of their evolution, and the X-ray luminosities of transient AXP and SGRs in quiescence lie in the luminosity range of X-ray

  4. X-ray pulsar rush in 1998

    International Nuclear Information System (INIS)

    Imanishi, K.; Tsujimoto, K.; Nishiuchi, Mamiko; Yokogawa, J.; Koyama, K.

    1999-01-01

    We present recent remarkable topics about discoveries of X-ray pulsars. 1. Pulsations from two Soft Gamma-ray Repeaters: These pulsars have enormously strong magnetic field (B ∼ 10 15 G), thus these are called as 'magnetar', new type of X-ray pulsars. 2. New Crab-like pulsars: These discoveries lead to suggesting universality of Crab-like pulsars. 3. An X-ray bursting millisecond pulsar: This is strong evidence for the recycle theory of generating radio millisecond pulsars. 4. X-ray pulsar rush in the SMC: This indicates the younger star formation history in the SMC. (author)

  5. A WHITE DWARF MERGER AS PROGENITOR OF THE ANOMALOUS X-RAY PULSAR 4U 0142+61?

    International Nuclear Information System (INIS)

    Rueda, J. A.; Boshkayev, K.; Izzo, L.; Ruffini, R.; Lorén-Aguilar, P.; Külebi, B.; Aznar-Siguán, G.; García-Berro, E.

    2013-01-01

    It has been recently proposed that massive, fast-rotating, highly magnetized white dwarfs could describe the observational properties of some of soft gamma-ray repeaters and anomalous X-ray pulsars (AXPs). Moreover, it has also been shown that high-field magnetic white dwarfs can be the outcome of white dwarf binary mergers. The products of these mergers consist of a hot central white dwarf surrounded by a rapidly rotating disk. Here we show that the merger of a double degenerate system can explain the characteristics of the peculiar AXP 4U 0142+61. This scenario accounts for the observed infrared excess. We also show that the observed properties of 4U 0142+6 are consistent with an approximately 1.2 M ☉ white dwarf, remnant of the coalescence of an original system made of two white dwarfs of masses 0.6 M ☉ and 1.0 M ☉ . Finally, we infer a post-merging age τ WD ≈ 64 kyr and a magnetic field B ≈ 2 × 10 8 G. Evidence for such a magnetic field may come from the possible detection of the electron cyclotron absorption feature observed between the B and V bands at ≈10 15 Hz in the spectrum of 4U 0142+61

  6. Spectroscopic Studies of X-Ray Binary Pulsars

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    ... those X-ray sources. A merit of investigating soft excess feature using XBP spectra is that it allows us to search pulse modulation of the soft component. Anomalous X-ray pulsars (AXPs) are also known to have a two component spectra, a steep power law and blackbody emission model (e.g., Mereghetti & Stella 1995).

  7. Anomalous X-Ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Wendin, G.

    1979-01-01

    The availability of tunable synchrotron radiation has made it possible systematically to perform x-ray diffraction studies in regions of anomalous scattering near absorption edges, e.g., in order to derive phase information for crystal structure determination. An overview is given of recent experimental and theoretical work and discussion of the properties of the anomalous atomic scattering factor, with emphasis on threshold resonances and damping effects. The results are applied to a discussion of the very strong anomalous dispersion recently observed near the L3 edge in a cesium complex. Also given is an overview of elements and levels where similar behavior can be expected. Finally, the influence of solid state and chemical effects on the absorption edge structure is discussed. 64 references.

  8. Anomalous x-ray scattering

    International Nuclear Information System (INIS)

    Wendin, G.

    1979-01-01

    The availability of tunable synchrotron radiation has made it possible systematically to perform x-ray diffraction studies in regions of anomalous scattering near absorption edges, e.g. in order to derive phase information for crystal structure determination. An overview is given of recent experimental and theoretical work and discuss the properties of the anomalous atomic scattering factor, with emphasis on threshold resonances and damping effects. The results are applied to a discussion of the very strong anomalous dispersion recently observed near the L 3 edge in a cesium complex. Also given is an overview of elements and levels where similar behavior can be expected. Finally, the influence of solid state and chemical effects on the absorption edge structure is discussed. 64 references

  9. Massive stars and X-ray pulsars

    International Nuclear Information System (INIS)

    Henrichs, H.

    1982-01-01

    This thesis is a collection of 7 separate articles entitled: long term changes in ultraviolet lines in γ CAS, UV observations of γ CAS: intermittent mass-loss enhancement, episodic mass loss in γ CAS and in other early-type stars, spin-up and spin-down of accreting neutron stars, an excentric close binary model for the X Persei system, has a 97 minute periodicity in 4U 1700-37/HD 153919 really been discovered, and, mass loss and stellar wind in massive X-ray binaries. (Articles 1, 2, 5, 6 and 7 have been previously published). The first three articles are concerned with the irregular mass loss in massive stars. The fourth critically reviews thoughts since 1972 on the origin of the changes in periodicity shown by X-ray pulsars. The last articles indicate the relation between massive stars and X-ray pulsars. (C.F.)

  10. X-ray pulsars: accretion flow deceleration

    International Nuclear Information System (INIS)

    Miller, G.S.

    1987-01-01

    X-ray pulsars are thought to be neutron stars that derive the energy for their x-ray emission by accreting material onto their magnetic polar caps. The accreting material and the x-ray pulsar atmospheres were idealized as fully ionized plasmas consisting only of electrons and protons. A high magnetic field (∼ 5 x 10 12 Gauss) permeates the atmospheric plasma, and causes the motion of atmospheric electrons perpendicular to the field to be quantized into discrete Landau levels. All atmospheric electrons initially lie in the Landau ground state, but in the author's calculations of Coulomb collisions between atmospheric electrons and accreting protons, he allows for processes that leave the electrons in the first excited Landau level. He also considers interactions between accreting protons and the collective modes of the atmospheric plasma. Division of the electromagnetic interaction of a fast proton with a magnetized plasma into single particle and collective effects is described in detail in Chapter 2. Deceleration of the accretion flow due to Coulomb collisions with atmospheric electrons and collective plasma effects was studied in a number of computer simulations. These simulations, along with a discussion of the physical state of the atmospheric plasma and its interactions with a past proton, are presented in Chapter 3. Details of the atmospheric model and a description of the results of the simulations are given in Chapter 4. Chapter 5 contains some brief concluding remarks, and some thoughts on future research

  11. A radio pulsar/X-ray binary link

    NARCIS (Netherlands)

    Archibald, A.M.; Stairs, I.H.; Ransom, S.M.; Kaspi, V.M.; Kondratiev, V.I.; Lorimer, D.R.; McLaughlin, M.A.; Boyles, J.; Hessels, J.W.T.; Lynch, R.; van Leeuwen, J.; Roberts, M.S.E.; Jenet, F.; Champion, D.J.; Rosen, R.; Barlow, B.N.; Dunlap, B.H.; Remillard, R.A.

    2009-01-01

    Radio pulsars with millisecond spin periods are thought to have been spun up by the transfer of matter and angular momentum from a low-mass companion star during an x-ray-emitting phase. The spin periods of the neutron stars in several such low-mass x-ray binary (LMXB) systems have been shown to be

  12. Diffraction anomalous fine structure using X-ray anomalous dispersion

    International Nuclear Information System (INIS)

    Soejima, Yuji; Kuwajima, Shuichiro

    1998-01-01

    A use of X-ray anomalous dispersion effects for structure investigation has recently been developed by using synchrotron radiation. One of the interesting method is the observation of anomalous fine structure which arise on diffraction intensity in energy region of incident X-ray at and higher than absorption edge. The phenomenon is so called Diffraction Anomalous Fine Structure (DAFS). DAFS originates in the same physical process an that of EXAFS: namely photoelectric effect at the corresponding atom and the interaction of photoelectron waves between the atom and neighboring atoms. In contrast with EXAFS, the method is available for only the crystalline materials, but shows effective advantages of the structure investigations by a use of diffraction: one is the site selectivity and the other is space selectivity. In the present study, demonstrations of a use of X-ray anomalous dispersion effect for the superstructure determination will be given for the case of PbZrO 3 , then recent trial investigations of DAFS in particular on the superlattice reflections will be introduced. In addition, we discuss about Forbidden Reflection near Edge Diffraction (FRED) which is more recently investigated as a new method of the structure analysis. (author)

  13. X-ray pulsars in nearby irregular galaxies

    Science.gov (United States)

    Yang, Jun

    2018-01-01

    The Small Magellanic Cloud (SMC), Large Magellanic Cloud (LMC) and Irregular Galaxy IC 10 are valuable laboratories to study the physical, temporal and statistical properties of the X-ray pulsar population with multi-satellite observations, in order to probe fundamental physics. The known distance of these galaxies can help us easily categorize the luminosity of the pulsars and their age difference can be helpful for for studying the origin and evolution of compact objects. Therefore, a complete archive of 116 XMM-Newton PN, 151 Chandra (Advanced CCD Imaging Spectrometer) ACIS, and 952 RXTE PCA observations for the pulsars in the Small Magellanic Cloud (SMC) were collected and analyzed, along with 42 XMM-Newton and 30 Chandra observations for the Large Magellanic Cloud, spanning 1997-2014. From a sample of 67 SMC pulsars we generate a suite of products for each pulsar detection: spin period, flux, event list, high time-resolution light-curve, pulse-profile, periodogram, and X-ray spectrum. Combining all three satellites, I generated complete histories of the spin periods, pulse amplitudes, pulsed fractions and X-ray luminosities. Many of the pulsars show variations in pulse period due to the combination of orbital motion and accretion torques. Long-term spin-up/down trends are seen in 28/25 pulsars respectively, pointing to sustained transfer of mass and angular momentum to the neutron star on decadal timescales. The distributions of pulse detection and flux as functions of spin period provide interesting findings: mapping boundaries of accretion-driven X-ray luminosity, and showing that fast pulsars (P<10 s) are rarely detected, which yet are more prone to giant outbursts. In parallel we compare the observed pulse profiles to our general relativity (GR) model of X-ray emission in order to constrain the physical parameters of the pulsars.In addition, we conduct a search for optical counterparts to X-ray sources in the local dwarf galaxy IC 10 to form a comparison

  14. Do we see accreting magnetars in X-ray pulsars?

    Directory of Open Access Journals (Sweden)

    Postnov K.A.

    2014-01-01

    Full Text Available Strong magnetic field of accreting neutron stars (1014 G is hard to probe by Xray spectroscopy but can be indirectly inferred from spin-up/spin-down measurement in X-ray pulsars. The existing observations of slowly rotating X-ray pulsars are discussed. It is shown that magnetic fields of neutron stars derived from these observations (or lower limits in some cases fall within the standard 1012-1013 G range. Claims about the evidence for accreting magnetars are critically discussed in the light of recent progress in understanding of accretion onto slowly rotating neutron stars in the subsonic regime.

  15. Tying Pulsar Timing in Radio and X-ray

    Science.gov (United States)

    Majid, W.

    2017-10-01

    Millisecond pulsars are a class of radio pulsars with extremely stable rotations. The excellent timing stability of millisecond pulsars can be used to study a wide variety of astrophysical phenomena in both radio and X-ray. We have developed a precision pulsar timing capability at NASA's Deep Space Network (DSN), which is deployed on large 70-m dishes. This program is now capable of producing precision pulsar timing of a large number of millisecond pulsars in radio. Often though there is a need to tie the pulse profiles of pulsars from radio to shorter wavelengths, for instance in X-ray timing campaigns. This poses special challenges that include the knowledge of absolute time in both detectors, pulse profile frequency evolution, dispersion measure monitoring, and systematic offsets across the frequency spectrum. We have recently initiated a high cadence timing program of the Crab pulsar to provide essential timing ephemerides for NASA's NICER mission. In this presentation, we will describe some of the challenges, including some early results of this campaign. This research was performed at the Jet Propulsion Laboratory, California Institute of Technology, under the Research and Technology Development Program, under a contract with the National Aeronautics and Space Administration.

  16. Nonlinear QED effects in X-ray emission of pulsars

    Energy Technology Data Exchange (ETDEWEB)

    Shakeri, Soroush [Department of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Haghighat, Mansour [Department of Physics, Shiraz University, Shiraz 71946-84795 (Iran, Islamic Republic of); Xue, She-Sheng, E-mail: Soroush.Shakeri@ph.iut.ac.ir, E-mail: m.haghighat@shirazu.ac.ir, E-mail: xue@icra.it [ICRANet, Piazzale della Repubblica 10, 65122, Pescara (Italy)

    2017-10-01

    In the presence of strong magnetic fields near pulsars, the QED vacuum becomes a birefringent medium due to nonlinear QED interactions. Here, we explore the impact of the effective photon-photon interaction on the polarization evolution of photons propagating through the magnetized QED vacuum of a pulsar. We solve the quantum Boltzmann equation within the framework of the Euler-Heisenberg Lagrangian to find the evolution of the Stokes parameters. We find that linearly polarized X-ray photons propagating outward in the magnetosphere of a rotating neutron star can acquire high values for the circular polarization parameter. Meanwhile, it is shown that the polarization characteristics of photons besides photon energy depend strongly on parameters of the pulsars such as magnetic field strength, inclination angle and rotational period. Our results are clear predictions of QED vacuum polarization effects in the near vicinity of magnetic stars which can be tested with the upcoming X-ray polarimetric observations.

  17. A radio pulsar/x-ray binary link.

    Science.gov (United States)

    Archibald, Anne M; Stairs, Ingrid H; Ransom, Scott M; Kaspi, Victoria M; Kondratiev, Vladislav I; Lorimer, Duncan R; McLaughlin, Maura A; Boyles, Jason; Hessels, Jason W T; Lynch, Ryan; van Leeuwen, Joeri; Roberts, Mallory S E; Jenet, Frederick; Champion, David J; Rosen, Rachel; Barlow, Brad N; Dunlap, Bart H; Remillard, Ronald A

    2009-06-12

    Radio pulsars with millisecond spin periods are thought to have been spun up by the transfer of matter and angular momentum from a low-mass companion star during an x-ray-emitting phase. The spin periods of the neutron stars in several such low-mass x-ray binary (LMXB) systems have been shown to be in the millisecond regime, but no radio pulsations have been detected. Here we report on detection and follow-up observations of a nearby radio millisecond pulsar (MSP) in a circular binary orbit with an optically identified companion star. Optical observations indicate that an accretion disk was present in this system within the past decade. Our optical data show no evidence that one exists today, suggesting that the radio MSP has turned on after a recent LMXB phase.

  18. Featured Image: A Slow-Spinning X-Ray Pulsar

    Science.gov (United States)

    Kohler, Susanna

    2017-05-01

    This image (click for a closer look!) reveals the sky location of a new discovery: the slowest spinning X-ray pulsar a spinning, highly magnetized neutron star ever found in an extragalactic globular cluster. The pulsar, XB091D (circled in the bottom left inset), lies in the globular cluster B091D in the Andromeda galaxy. In a recent study led by Ivan Zolotukhin (University of Toulouse, Moscow State University, and Special Astrophysical Observatory of the Russian Academy of Sciences), a team of scientists details the importance of this discovery. This pulsar is gradually spinning faster and faster a process thats known as recycling, thought to occur as a pulsar accretes material from a donor star in a binary system. Zolotukhin and collaborators think that this particular pairing formed relatively recently, when the pulsar captured a passing star into a binary system. Were now seeing it in a unique stage of evolution where the pulsar is just starting to get recycled. For more information, check out the paper below!CitationIvan Yu. Zolotukhin et al 2017 ApJ 839 125. doi:10.3847/1538-4357/aa689d

  19. Be/X-Ray Pulsar Binary Science with LOFT

    Science.gov (United States)

    Wilson-Hodge, Colleen A.

    2011-01-01

    Accretion disks are ubiquitous in astronomical sources. Accretion powered pulsars are a good test bed for accretion disk physics, because unlike for other objects, the spin of the neutron star is directly observable allowing us to see the effects of angular momentum transfer onto the pulsar. The combination of a sensitive wide-field monitor and the large area detector on LOFT will enable new detailed studies of accretion powered pulsars which I will review. RXTE observations have shown an unusually high number of Be/X-ray pulsar binaries in the SMC. Unlike binaries in the Milky Way, these systems are all at the same distance, allowing detailed population studies using the sensitive LOFT WFM, potentially providing connections to star formation episodes. For Galactic accreting pulsar systems, LOFT will allow measurement of spectral variations within individual pulses, mapping the accretion column in detail for the first time. LOFT will also provide better constraints on magnetic fields in accreting pulsars, allowing measurements of cyclotron features, observations of transitions into the centrifugal inhibition regime, and monitoring of spin-up rate vs flux correlations. Coordinated multi-wavelength observations are crucial to extracting the best science from LOFT from these and numerous other objects.

  20. The X-ray emission properties of millisecond pulsars

    OpenAIRE

    Becker, W.; Trümper, J.

    1998-01-01

    Until now X-radiation from nine millisecond pulsars has been detected. In the present paper we summarize the observations and show the results of a re-analysis of archival ROSAT data. In addition we present the results of recent observations of PSR J0437-4715 with the ROSAT PSPC and HRI detectors. We show that the pulsed fraction is independent of energy in the range 0.1-2.4 keV. The pulse width as measured at X-ray energies is comparable with that observed in the radio domain. An upper limit...

  1. Detectability of rotation-powered pulsars in future hard X-ray surveys

    International Nuclear Information System (INIS)

    Wang Wei

    2009-01-01

    Recent INTEGRAL/IBIS hard X-ray surveys have detected about 10 young pulsars. We show hard X-ray properties of these 10 young pulsars, which have a luminosity of 10 33 -10 37 erg s -1 and a photon index of 1.6-2.1 in the energy range of 20-100 keV. The correlation between X-ray luminosity and spin-down power of L X ∝ L sd 1.31 suggests that the hard X-ray emission in rotation-powered pulsars is dominated by the pulsar wind nebula (PWN) component. Assuming spectral properties are similar in 20-100 keV and 2-10 keV for both the pulsar and PWN components, the hard X-ray luminosity and flux of 39 known young X-ray pulsars and 8 millisecond pulsars are obtained, and a correlation of L X ∝ L sd 1.5 is derived. About 20 known young X-ray pulsars and 1 millisecond pulsars could be detected with future INTEGRAL and HXMT surveys. We also carry out Monte Carlo simulations of hard X-ray pulsars in the Galaxy and the Gould Belt, assuming values for the pulsar birth rate, initial position, proper motion velocity, period, and magnetic field distribution and evolution based on observational statistics and the L X - L sd relations: L X ∝ L sd 1.31 and L X ∝ L sd 1.5 . More than 40 young pulsars (mostly in the Galactic plane) could be detected after ten years of INTEGRAL surveys and the launch of HXMT. So, the young pulsars would be a significant part of the hard X-ray source population in the sky, and will contribute to unidentified hard X-ray sources in present and future hard X-ray surveys by INTEGRAL and HXMT.

  2. Orbitally-Modulated X-rays From Millisecond Pulsar Binaries

    Science.gov (United States)

    Kust Harding, Alice; Wadiasingh, Zorawar; Venter, Christo; Boettcher, Markus; Baring, Matthew G.

    2017-06-01

    A large number of new Black Widow (BW) and Redback (RB) rotation-powered millisecond pulsars have been discovered through radio searches of unidentified Fermi sources, increasing the known number of these systems from 4 to 28. We model the high-energy synchrotron emission component from particles accelerated to several TeV in intrabinary shocks in two known BW and RB systems, and its predicted modulation at the binary orbital period. Constructing a geometric model of the shock, we use radio eclipse data in conjunction with optical constraints on the binary inclination angle to constrain the shock stagnation point distance from either the pulsar or companion star. We next model the X-ray synchrotron orbital light curves and compare them to those observed from the PSR B1957+20, where the shock surrounds the companion, and PSR J1023+0038, where the shock surrounds the pulsar, to constrain the bulk Lorentz factor of the wind flow as well as further constrain the inclination angle.

  3. The Radio and X-ray Mode-Switching Pulsar PSR B0943+10

    Indian Academy of Sciences (India)

    Sandro Mereghetti

    2017-09-12

    Sep 12, 2017 ... The study of such synchronous radio/X-ray mode switching opens a new window to investigate the processes responsible for the pulsar radio and high-energy emission. Here we review the main X-ray properties of PSR B0943+10 derived from recent coordinated X-ray and radio observations. Keywords.

  4. THE RADIATIVE X-RAY AND GAMMA-RAY EFFICIENCIES OF ROTATION-POWERED PULSARS

    International Nuclear Information System (INIS)

    Vink, Jacco; Bamba, Aya; Yamazaki, Ryo

    2011-01-01

    We present a statistical analysis of the X-ray luminosity of rotation-powered pulsars and their surrounding nebulae using the sample of Kargaltsev and Pavlov, and we complement this with an analysis of the γ-ray emission of Fermi-detected pulsars. We report a strong trend in the efficiency with which spin-down power is converted to X-ray and γ-ray emission with characteristic age: young pulsars and their surrounding nebulae are efficient X-ray emitters, whereas in contrast old pulsars are efficient γ-ray emitters. We divided the X-ray sample in a young (τ c 4 yr) and old sample and used linear regression to search for correlations between the logarithm of the X-ray and γ-ray luminosities and the logarithms of the periods and period derivatives. The X-ray emission from young pulsars and their nebulae are both consistent with L X ∝ P-dot 3 /P 6 . For old pulsars and their nebulae the X-ray luminosity is consistent with a more or less constant efficiency η≡L X / E-dot rot ∼8x10 -5 . For the γ-ray luminosity we confirm that L γ ∝ √E-dot rot . We discuss these findings in the context of pair production inside pulsar magnetospheres and the striped wind model. We suggest that the striped wind model may explain the similarity between the X-ray properties of the pulsar wind nebulae and the pulsars themselves, which according to the striped wind model may both find their origin outside the light cylinder, in the pulsar wind zone.

  5. Rotational and X-ray luminosity evolution of high-B radio pulsars

    Science.gov (United States)

    Benli, Onur; Ertan, Ünal

    2018-05-01

    In continuation of our earlier work on the long-term evolution of the so-called high-B radio pulsars (HBRPs) with measured braking indices, we have investigated the long-term evolution of the remaining five HBRPs for which braking indices have not been measured yet. This completes our source-by-source analyses of HBRPs in the fallback disc model that was also applied earlier to anomalous X-ray pulsars (AXPs), soft gamma repeaters (SGRs), and dim isolated neutron stars (XDINs). Our results show that the X-ray luminosities and the rotational properties of these rather different neutron star populations can be acquired by neutron stars with fallback discs as a result of differences in their initial conditions, namely the initial disc mass, initial period and the dipole field strength. For the five HBRPs, unlike for AXPs, SGRs and XDINs, our results do not constrain the dipole field strengths of the sources. We obtain evolutionary paths leading to the properties of HBRPs in the propeller phase with dipole fields sufficiently strong to produce pulsed radio emission.

  6. SEXTANT X-Ray Pulsar Navigation Demonstration: Initial On-Orbit Results

    Science.gov (United States)

    Mitchell, Jason W.; Winternitz, Luke B.; Hassouneh, Munther A.; Price, Samuel R.; Semper, Sean R.; Yu, Wayne H.; Ray, Paul S.; Wolf, Michael T.; Kerr, Matthew; Wood, Kent S.; hide

    2018-01-01

    Millisecond pulsars (MSPs) are rapidly rotating neutron stars that appear to pulsate across the electromagnetic spectrum. Some MSPs have long-term timing stability that rivals that of atomic clocks. Pulse arrival phase can be predicted with great accuracy at any reference point in the Solar System through use of a pulsar timing model on a spacecraft. Comparing observed phase to predictions gives information that may be used in a navigation process. Why X-rays? Some stable MSPs have conveniently detectable X-ray emissions. X-rays are immune to interstellar dispersion effects thought to limit radio pulsar timing models. Highly directional compact detectors possible.

  7. Ultraluminous X-ray sources as neutrino pulsars

    Science.gov (United States)

    Mushtukov, Alexan6der A.; Tsygankov, Sergey S.; Suleimanov, Valery F.; Poutanen, Juri

    2018-02-01

    The classical limit on the accretion luminosity of a neutron star is given by the Eddington luminosity. The advanced models of accretion onto magnetized neutron stars account for the appearance of magnetically confined accretion columns and allow the accretion luminosity to be higher than the Eddington value by a factor of tens. However, the recent discovery of pulsations from ultraluminous X-ray source (ULX) in NGC 5907 demonstrates that the accretion luminosity can exceed the Eddington value up to by a factor of 500. We propose a model explaining observational properties of ULX-1 in NGC 5907 without any ad hoc assumptions. We show that the accretion column at extreme luminosity becomes advective. Enormous energy release within a small geometrical volume and advection result in very high temperatures at the bottom of accretion column, which demand to account for the energy losses due to neutrino emission which can be even more effective than the radiation energy losses. We show that the total luminosity at the mass accretion rates above 1021 g s-1 is dominated by the neutrino emission similarly to the case of core-collapse supernovae. We argue that the accretion rate measurements based on detected photon luminosity in case of bright ULXs powered by neutron stars can be largely underestimated due to intense neutrino emission. The recently discovered pulsating ULX-1 in galaxy NGC 5907 with photon luminosity of ˜ 10^{41} {erg s^{-1}} is expected to be even brighter in neutrinos and is thus the first known Neutrino Pulsar.

  8. Magnetar-like X-Ray Bursts Suppress Pulsar Radio Emission

    Energy Technology Data Exchange (ETDEWEB)

    Archibald, R. F.; Lyutikov, M.; Kaspi, V. M.; Tendulkar, S. P. [Department of Physics and McGill Space Institute, McGill University, 3600 University Street, Montreal, QC H3A 2T8 (Canada); Burgay, M.; Possenti, A. [INAF–Osservatorio Astronomico di Cagliari, Via della Scienza 5, I-09047 Selargius (Italy); Esposito, P.; Rea, N. [Anton Pannekoek Institute for Astronomy, University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands); Israel, G. [INAF–Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monteporzio Catone, Roma (Italy); Kerr, M. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Sarkissian, J. [CSIRO Astronomy and Space Science, Parkes Observatory, P.O. Box 276, Parkes, NSW 2870 (Australia); Scholz, P., E-mail: archibald@astro.utoronto.ca [National Research Council of Canada, Herzberg Astronomy and Astrophysics, Dominion Radio Astrophysical Observatory, P.O. Box 248, Penticton, BC V2A 6J9 (Canada)

    2017-11-10

    Rotation-powered pulsars and magnetars are two different observational manifestations of neutron stars: rotation-powered pulsars are rapidly spinning objects that are mostly observed as pulsating radio sources, while magnetars, neutron stars with the highest known magnetic fields, often emit short-duration X-ray bursts. Here, we report simultaneous observations of the high-magnetic-field radio pulsar PSR J1119−6127 at X-ray, with XMM-Newton and NuSTAR , and at radio energies with the Parkes radio telescope, during a period of magnetar-like bursts. The rotationally powered radio emission shuts off coincident with the occurrence of multiple X-ray bursts and recovers on a timescale of ∼70 s. These observations of related radio and X-ray phenomena further solidify the connection between radio pulsars and magnetars and suggest that the pair plasma produced in bursts can disrupt the acceleration mechanism of radio-emitting particles.

  9. X-Ray Pulsar Based Navigation and Time Determination, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Microcosm will build on the Phase I X-ray pulsar-based navigation and timing (XNAV) feasibility assessment to develop a detailed XNAV simulation capability to...

  10. The Radio and X-ray Mode-Switching Pulsar PSR B0943+10

    Indian Academy of Sciences (India)

    Sandro Mereghetti

    2017-09-12

    Sep 12, 2017 ... synchronous radio/X-ray mode switching opens a new window to investigate the processes responsible for the pulsar radio and ... characteristic age τ = 5 Myr and a rotational energy loss rate ˙Erot = 1032 erg s. −1 ..... B0943+10 is thus similar to other old-and middle-aged pulsars from which thermal X-rays ...

  11. Spectroscopic Studies of X-Ray Binary Pulsars

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    X-ray spectra of black hole binaries and active galactic nuclei show a non- thermal power law spectra extended over wide energy range toward hard X-rays to γ-rays. In contrast to these X-ray sources, XBPs fundamentally show a power law spectra with photon indices 1–2 with high-energy turnover at relatively low energies.

  12. Ultraluminous X-ray sources as neutrino pulsars

    Science.gov (United States)

    Mushtukov, Alexander A.; Tsygankov, Sergey S.; Suleimanov, Valery F.; Poutanen, Juri

    2018-05-01

    The classical limit on the accretion luminosity of a neutron star is given by the Eddington luminosity. The advanced models of accretion on to magnetized neutron stars account for the appearance of magnetically confined accretion columns and allow the accretion luminosity to be higher than the Eddington value by a factor of tens. However, the recent discovery of pulsations from ultraluminous X-ray source (ULX) in NGC 5907 demonstrates that the accretion luminosity can exceed the Eddington value up to by a factor of 500. We propose a model explaining observational properties of ULX-1 in NGC 5907 without any ad hoc assumptions. We show that the accretion column at extreme luminosity becomes advective. Enormous energy release within a small geometrical volume and advection result in very high temperatures at the bottom of accretion column, which demand to account for the energy losses due to neutrino emission which can be even more effective than the radiation energy losses. We show that the total luminosity at the mass accretion rates above 1021 g s-1 is dominated by the neutrino emission similarly to the case of core-collapse supernovae. We argue that the accretion rate measurements based on detected photon luminosity in case of bright ULXs powered by neutron stars can be largely underestimated due to intense neutrino emission. The recently discovered pulsating ULX-1 in galaxy NGC 5907 with photon luminosity of {˜ } 10^{41} {erg s^{-1}} is expected to be even brighter in neutrinos and is thus the first known Neutrino Pulsar.

  13. Soft X-ray emission from the radio pulsar PSR 0656 + 14

    Science.gov (United States)

    Cordova, F. A.; Middleditch, J.; Hjellming, R. M.; Mason, K. O.

    1989-01-01

    A radio source with a flux density of a few mJy was found in the error region of the soft X-ray source E0656 + 14, and identified as the radio pulsar PSR 0656 + 14. The radio source has a steep, nonthermal spectrum and a high degree of linear (62 percent) and circular (19 percent) polarization. The X-ray spectrum of the pulsar is among the softest sources observed with the Einstein Observatory. The X-ray data taken with the Einstein imaging proportional counter (IPC) permit a range of blackbody temperatures of 3-6 x 10 to the 5th K, and an equivalent column density of hydrogen smaller than 4 x 10 to the 20th/sq cm. If the assumption is made that the X-ray flux is thermal radiation from surface of the neutron star, then the pulsar must be at a distance smaller than 550 pc, consistent with the low dispersion measure of PSR 0656 + 14. The X-ray timing data suggest that the X-ray emission is modulated at the pulsar's 0.385-s spin period with an amplitude of 18 percent + or - 6 percent, and that there is a 0.0002 probability that this is spurious. It was noted that PSR 0656 + 14 is close to the geometric center of a 20-deg diameter soft X-ray emitting ring called the Gemini-Monoceros enhancement. The close distance of the pulsar, together with its relatively young age of 1.1 x 10 to the 5th yr, makes it possible that the ring is a supernova remnant from the explosion of the pulsar's progenitor. A radio source extending over a region 1.2 to 3.3 arcmin south of the pulsar is a candidate for association with the pulsar.

  14. X-ray and γ-ray studies of the millisecond pulsar and possible X-ray binary/radio pulsar transition object PSR J1723-2837

    Energy Technology Data Exchange (ETDEWEB)

    Bogdanov, Slavko [Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Esposito, Paolo [INAF-IASF Milano, via East Bassini 15, I-20133 Milano (Italy); Crawford III, Fronefield [Department of Physics and Astronomy, Franklin and Marshall College, P.O. Box 3003, Lancaster, PA 17604 (United States); Possenti, Andrea [INAF-Osservatorio Astronomico di Cagliari, Loc. Poggio dei Pini, Strada 54, I-09012 Capoterra (Italy); McLaughlin, Maura A. [Department of Physics and Astronomy, West Virginia University, 210E Hodges Hall, Morgantown, WV 26506 (United States); Freire, Paulo, E-mail: slavko@astro.columbia.edu [Max-Planck-Institut für Radioastronomie, D-53121 Bonn (Germany)

    2014-01-20

    We present X-ray observations of the 'redback' eclipsing radio millisecond pulsar (MSP) and candidate radio pulsar/X-ray binary transition object PSR J1723-2837. The X-ray emission from the system is predominantly non-thermal and exhibits pronounced variability as a function of orbital phase, with a factor of ∼2 reduction in brightness around superior conjunction. Such temporal behavior appears to be a defining characteristic of this variety of peculiar MSP binaries and is likely caused by a partial geometric occultation by the main-sequence-like companion of a shock within the binary. There is no indication of diffuse X-ray emission from a bow shock or pulsar wind nebula associated with the pulsar. We also report on a search for point source emission and γ-ray pulsations in Fermi Large Area Telescope data using a likelihood analysis and photon probability weighting. Although PSR J1723-2837 is consistent with being a γ-ray point source, due to the strong Galactic diffuse emission at its position a definitive association cannot be established. No statistically significant pulsations or modulation at the orbital period are detected. For a presumed detection, the implied γ-ray luminosity is ≲5% of its spin-down power. This indicates that PSR J1723-2837 is either one of the least efficient γ-ray producing MSPs or, if the detection is spurious, the γ-ray emission pattern is not directed toward us.

  15. Synchronous x-ray and radio mode switches: a rapid global transformation of the pulsar magnetosphere.

    Science.gov (United States)

    Hermsen, W; Hessels, J W T; Kuiper, L; van Leeuwen, J; Mitra, D; de Plaa, J; Rankin, J M; Stappers, B W; Wright, G A E; Basu, R; Alexov, A; Coenen, T; Grießmeier, J-M; Hassall, T E; Karastergiou, A; Keane, E; Kondratiev, V I; Kramer, M; Kuniyoshi, M; Noutsos, A; Serylak, M; Pilia, M; Sobey, C; Weltevrede, P; Zagkouris, K; Asgekar, A; Avruch, I M; Batejat, F; Bell, M E; Bell, M R; Bentum, M J; Bernardi, G; Best, P; Bîrzan, L; Bonafede, A; Breitling, F; Broderick, J; Brüggen, M; Butcher, H R; Ciardi, B; Duscha, S; Eislöffel, J; Falcke, H; Fender, R; Ferrari, C; Frieswijk, W; Garrett, M A; de Gasperin, F; de Geus, E; Gunst, A W; Heald, G; Hoeft, M; Horneffer, A; Iacobelli, M; Kuper, G; Maat, P; Macario, G; Markoff, S; McKean, J P; Mevius, M; Miller-Jones, J C A; Morganti, R; Munk, H; Orrú, E; Paas, H; Pandey-Pommier, M; Pandey, V N; Pizzo, R; Polatidis, A G; Rawlings, S; Reich, W; Röttgering, H; Scaife, A M M; Schoenmakers, A; Shulevski, A; Sluman, J; Steinmetz, M; Tagger, M; Tang, Y; Tasse, C; ter Veen, S; Vermeulen, R; van de Brink, R H; van Weeren, R J; Wijers, R A M J; Wise, M W; Wucknitz, O; Yatawatta, S; Zarka, P

    2013-01-25

    Pulsars emit from low-frequency radio waves up to high-energy gamma-rays, generated anywhere from the stellar surface out to the edge of the magnetosphere. Detecting correlated mode changes across the electromagnetic spectrum is therefore key to understanding the physical relationship among the emission sites. Through simultaneous observations, we detected synchronous switching in the radio and x-ray emission properties of PSR B0943+10. When the pulsar is in a sustained radio-"bright" mode, the x-rays show only an unpulsed, nonthermal component. Conversely, when the pulsar is in a radio-"quiet" mode, the x-ray luminosity more than doubles and a 100% pulsed thermal component is observed along with the nonthermal component. This indicates rapid, global changes to the conditions in the magnetosphere, which challenge all proposed pulsar emission theories.

  16. THERMAL X-RAY EMISSION FROM THE SHOCKED STELLAR WIND OF PULSAR GAMMA-RAY BINARIES

    Energy Technology Data Exchange (ETDEWEB)

    Zabalza, V.; Paredes, J. M. [Departament d' Astronomia i Meteorologia, Institut de Ciencies del Cosmos (ICC), Universitat de Barcelona (IEEC-UB), Marti i Franques 1, E08028 Barcelona (Spain); Bosch-Ramon, V., E-mail: vzabalza@am.ub.es [Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland)

    2011-12-10

    Gamma-ray-loud X-ray binaries are binary systems that show non-thermal broadband emission from radio to gamma rays. If the system comprises a massive star and a young non-accreting pulsar, their winds will collide producing broadband non-thermal emission, most likely originated in the shocked pulsar wind. Thermal X-ray emission is expected from the shocked stellar wind, but until now it has neither been detected nor studied in the context of gamma-ray binaries. We present a semi-analytic model of the thermal X-ray emission from the shocked stellar wind in pulsar gamma-ray binaries, and find that the thermal X-ray emission increases monotonically with the pulsar spin-down luminosity, reaching luminosities of the order of 10{sup 33} erg s{sup -1}. The lack of thermal features in the X-ray spectrum of gamma-ray binaries can then be used to constrain the properties of the pulsar and stellar winds. By fitting the observed X-ray spectra of gamma-ray binaries with a source model composed of an absorbed non-thermal power law and the computed thermal X-ray emission, we are able to derive upper limits on the spin-down luminosity of the putative pulsar. We applied this method to LS 5039, the only gamma-ray binary with a radial, powerful wind, and obtain an upper limit on the pulsar spin-down luminosity of {approx}6 Multiplication-Sign 10{sup 36} erg s{sup -1}. Given the energetic constraints from its high-energy gamma-ray emission, a non-thermal to spin-down luminosity ratio very close to unity may be required.

  17. Phase Evolution of the Crab Pulsar between Radio and X-Ray

    Energy Technology Data Exchange (ETDEWEB)

    Yan, L. L.; Ge, M. Y.; Zheng, S. J.; Lu, F. J.; Tuo, Y. L.; Zhang, S. N.; Lu, Y. [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Yuan, J. P.; Tong, H. [Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, Xinjiang 830011 (China); Han, J. L. [National Astronomical Observatory, Chinese Academy of Sciences, Jia 20 Datun Road, Beijing 100012 (China); Du, Y. J., E-mail: yanlinli@ihep.ac.cn [Qian Xuesen Laboratory of Space Technology, No. 104, Youyi Road, Haidian District, Beijing 100094 (China)

    2017-08-20

    We study the X-ray phases of the Crab pulsar utilizing the 11-year observations from the Rossi X-ray Timing Explorer , 6-year radio observations from Nanshan Telescope, and the ephemeris from Jodrell Bank Observatory. It is found that the X-ray phases in different energy bands and the radio phases from the Nanshan Telescope show similar behaviors, including long-time evolution and short-time variations. Such strong correlations between the X-ray and radio phases imply that the radio and X-ray timing noises are both generated from the pulsar spin that cannot be well described by the the monthly ephemeris from the Jodrell Bank observatory. When using the Nanshan phases as references to study the X-ray timing noise, it has a significantly smaller variation amplitude and shows no long-time evolution, with a change rate of (−1.1 ± 1.1) × 10{sup −7} periods per day. These results show that the distance of the X-ray and radio emission regions on the Crab pulsar has no detectable secular change, and it is unlikely that the timing noises resulted from any unique physical processes in the radio or X-ray emitting regions. The similar behaviors of the X-ray and radio timing noises also imply that the variation of the interstellar medium is not the origin of the Crab pulsar’s timing noises, which is consistent with the results obtained from the multi-frequency radio observations of PSR B1540−06.

  18. Deep Chandra Survey of the Small Magellanic Cloud. II. Timing Analysis of X-Ray Pulsars

    Energy Technology Data Exchange (ETDEWEB)

    Hong, JaeSub; Antoniou, Vallia; Zezas, Andreas; Drake, Jeremy J.; Plucinsky, Paul P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Haberl, Frank [Max-Planck-Institut für extraterrestrische Physik, Giessenbach straße, D-85748 Garching (Germany); Sasaki, Manami [Friedrich-Alexander-Universität Erlangen-Nürnberg, Sternwartstrasse 7, 96049 Bamberg (Germany); Laycock, Silas, E-mail: jaesub@head.cfa.harvard.edu [Department of Physics, University of Massachusetts Lowell, MA 01854 (United States)

    2017-09-20

    We report the timing analysis results of X-ray pulsars from a recent deep Chandra survey of the Small Magellanic Cloud (SMC). We analyzed a total exposure of 1.4 Ms from 31 observations over a 1.2 deg{sup 2} region in the SMC under a Chandra X-ray Visionary Program. Using the Lomb–Scargle and epoch-folding techniques, we detected periodic modulations from 20 pulsars and a new candidate pulsar. The survey also covered 11 other pulsars with no clear sign of periodic modulation. The 0.5–8 keV X-ray luminosity ( L {sub X} ) of the pulsars ranges from 10{sup 34} to 10{sup 37} erg s{sup −1} at 60 kpc. All of the Chandra sources with L {sub X} ≳ 4 × 10{sup 35} erg s{sup −1} exhibit X-ray pulsations. The X-ray spectra of the SMC pulsars (and high-mass X-ray binaries) are in general harder than those of the SMC field population. All but SXP 8.02 can be fitted by an absorbed power-law model with a photon index of Γ ≲ 1.5. The X-ray spectrum of the known magnetar SXP 8.02 is better fitted with a two-temperature blackbody model. Newly measured pulsation periods of SXP 51.0, SXP 214, and SXP 701, are significantly different from the previous XMM-Newton and RXTE measurements. This survey provides a rich data set for energy-dependent pulse profile modeling. Six pulsars show an almost eclipse-like dip in the pulse profile. Phase-resolved spectral analysis reveals diverse spectral variations during pulsation cycles: e.g., for an absorbed power-law model, some exhibit an (anti)-correlation between absorption and X-ray flux, while others show more intrinsic spectral variation (i.e., changes in photon indices).

  19. Spectral Properties of the X-ray Binary Pulsar LMC X-4 during ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Spectral Properties of the X-ray Binary Pulsar LMC X-4 during. Different Intensity States. S. Naik & B. Paul Tata ... The value of equivalent hydrogen column density NH was set to have a lower threshold of 0.055×1022cm. −2 which is the Galactic column density towards this source. The blackbody temperature was kept fixed ...

  20. Radio upper limits for the accreting millisecond X-ray pulsar IGR J17511-3057

    NARCIS (Netherlands)

    Miller-Jones, J.C.A.; Russell, D.M.; Migliari, S.

    2009-01-01

    We report on recent radio observations of the newly-detected accreting millisecond X-ray pulsar, IGR J17511-3057 (ATels #2196, #2197, #2198, #2199, #2215, #2216, #2220, #2221). We used the Very Large Array (VLA) to observe the source under observing program AM971. The array was in its relatively

  1. Application of X-Ray Pulsar Navigation: A Characterization of the Earth Orbit Trade Space

    Science.gov (United States)

    Yu, Wayne Hong

    2016-01-01

    The potential for pulsars as a navigation source has been studied since their discovery in 1967. X-ray pulsar navigation (XNAV) is a celestial navigation system that uses the consistent timing nature of x-ray photons from millisecond pulsars (MSP) to perform space navigation. By comparing the detected arrival of x-ray photons to a reference database of expected pulsar light-curve timing models, one can infer a range and range rate measurement based on light time delay. Much of the challenge of XNAV comes from the faint signal, availability, and distant nature of pulsars. This is a study of potential pulsar XNAV measurements to measure extended Kalman filter (EKF) tracking performance with a wide trade space of bounded Earth orbits, using a simulation of existing x-ray detector space hardware. An example of an x-ray detector for XNAV is the NASA Station Explorer for X-ray Timing and Navigation (SEXTANT) mission, a technology demonstration of XNAV set to perform on the International Space Station (ISS) in late 2016early 2017. XNAV hardware implementation is driven by trajectory and environmental influences which add noise to the x-ray pulse signal. In a closed Earth orbit, the radiation environment can exponentially increase the signal noise from x-ray pulsar sources, decreasing the quality and frequency of measurements. The SEXTANT mission in particular improves on the signal to noise ratio by focusing an array of 56 x-ray silicon drift detectors at one pulsar target at a time. This reduces timing glitches and other timing noise contributions from ambient x-ray sources to within a 100 nanosecond resolution. This study also considers the SEXTANT scheduling challenges inherent in a single target observation. Finally, as the navigation sources are now relatively inertial targets, XNAV measurements are also subject to periods of occultation from various celestial bodies. This study focuses on the characterization of these drivers in closed Earth orbits and is not a

  2. X-ray counterpart candidates for six new γ-ray pulsars

    Science.gov (United States)

    Zyuzin, Dmitry A.; Karpova, Anna V.; Shibanov, Yuriy A.

    2018-05-01

    Using archival X-ray data, we have found point-like X-ray counterpart candidates positionally coincident with six γ-ray pulsars discovered recently in the Fermi Gamma-ray Space Telescope data by the Einstein@Home project. The candidates for PSRs J0002+6216, J0554+3107, J1844-0346, and J1105-6037 are detected with Swift, and those for PSRs J0359+5414 and J2017+3625 are detected with Chandra. Despite a low count statistics for some candidates, assuming plausible constraints on the absorbing column density towards the pulsars, we show that X-ray spectral properties for all of them are consistent with those observed for other pulsars. J0359+5414 is the most reliably identified object. We detect a nebula around it, whose spectrum and extent suggest that this is a pulsar wind nebula powered by the pulsar. Associations of J0002+6216 and J1844-0346 with supernova remnants CTB 1 and G28.6-0.1 are proposed.

  3. Building X-ray pulsar timing model without the use of radio parameters

    Science.gov (United States)

    Sun, Hai-feng; Sun, Xiong; Fang, Hai-yan; Shen, Li-rong; Cong, Shao-peng; Liu, Yan-ming; Li, Xiao-ping; Bao, Wei-min

    2018-02-01

    This paper develops a timing solution for the X-ray pulsar timing model without the use of the initial radio model parameters. First, we address the problem of phase ambiguities for the pre-fit residuals in the construction of pulsar timing model. To improve the estimation accuracy of the pulse time of arrival (TOA), we have deduced the general form of test statistics in Fourier transform, and discussed their estimation performances. Meanwhile, a fast maximum likelihood (FML) technique is presented to estimate the pulse TOA, which outperforms cross correlation (CC) estimator and exhibits a performance comparable with maximum likelihood (ML) estimator in spite of a much less reduced computational complexity. Depending on the strategy of the difference minimum of pre-fit residuals, we present an effective forced phase-connected technique to achieve initial model parameters. Then, we use the observations with the Rossi X-Ray Timing Explorer (RXTE) and X-ray pulsar navigation-I (XPNAV-1) satellites for experimental studies, and discuss main differences for the root mean square (RMS) residuals calculated with the X-ray and radio ephemerides. Finally, a chi-square value (CSV) of pulse profiles is presented as a complementary indicator to the RMS residuals for evaluating the model parameters. The results show that the proposed timing solution is valid and effective, and the obtained model parameters can be a reasonable alternative to the radio ephemeris.

  4. CubeSAT X-ray Telescope (CubeX) for Elemental Abundance Mapping of Airless Bodies and X-ray Pulsar Navigation (XNAV)

    Science.gov (United States)

    Romaine, S.; Hong, J.; Elvis, M.

    2017-09-01

    The CubeSAT X-ray Telescope (CubeX) is a concept for a 12U planetary X-ray telescope, which utilizes Miniature Wolter-I X-ray optics (MiXO) and a combination of X-ray CMOS and SDD sensors for the focal plane. CubeX will map the surface elemental composition of diverse airless bodies using X-ray Fluorescence (XRF), which can help us to understand the formation and evolutionary history of the individual bodies and the workings of the Solar system as a whole. CubeX will also conduct a feasibility and performance test of X-ray pulsar timing based deep space navigation (XNAV), which can lower operation costs of space navigation and enable autonomous deep space navigation.

  5. Diversity in Neutron Stars: X-ray Observations of High-Magnetic-Field Radio Pulsars

    Science.gov (United States)

    Kaspi, Victoria M.

    2011-09-01

    Young neutron stars show a surprising diversity in observational behavior. Many different `classes' of these objects are presently inferred, including rotation-powered pulsars, magnetars, CCOs, INSs, among others. In this presentation I review a critical group of neutron stars that sit at the juncture of multiple such classes: the high-magnetic field rotation-powered pulsars. Deep X-ray studies of multiple high-B sources have now been done, and have revealed possible evidence for enhanced thermal emission, as predicted by models of magneto-thermal evolution. These observations will be described, and the evidence for enhanced cooling presented.

  6. Radio upper limits for the accreting millisecond X-ray pulsar IGR J17511-3057

    Science.gov (United States)

    Miller-Jones, J. C. A.; Russell, D. M.; Migliari, S.

    2009-10-01

    We report on recent radio observations of the newly-detected accreting millisecond X-ray pulsar, IGR J17511-3057 (ATels #2196, #2197, #2198, #2199, #2215, #2216, #2220, #2221). We used the Very Large Array (VLA) to observe the source under observing program AM971. The array was in its relatively compact 'C' and 'DNC' configurations, and the observations were made at 8.46 GHz. In no case was the source significantly detected.

  7. Observation of the X-ray pulsar A0535 + 26 with the FIGARO II experiment

    Science.gov (United States)

    Olive, J. F.; Agrinier, B.; Barouch, E.; Comte, R.; Costa, E.; Cusumano, G. C.; Gerardi, G.; Mandrou, P.; Masnou, J. L.; Massaro, E.; Matt, G.; Mineo, T.; Niel, M.; Parlier, B.; Sacco, B.; Salvati, M.; Scarsi, L.

    1993-01-01

    The FIGARO II experiment observed the transient X-ray pulsar A0535 + 26 in the 0.15-4 MeV range, only 11.1 +/- 4 days after an expected outburst. We found evidence for periodicity at 103.2 sec close to the extrapolated value. The light-curve and the spectral shape of this low energy gamma-ray emission are presented here.

  8. Macromolecular X-ray structure determination using weak, single-wavelength anomalous data

    Energy Technology Data Exchange (ETDEWEB)

    Bunkóczi, Gábor; McCoy, Airlie J.; Echols, Nathaniel; Grosse-Kunstleve, Ralf W.; Adams, Paul D.; Holton, James M.; Read, Randy J.; Terwilliger, Thomas C.

    2014-12-22

    We describe a likelihood-based method for determining the substructure of anomalously scattering atoms in macromolecular crystals that allows successful structure determination by single-wavelength anomalous diffraction (SAD) X-ray analysis with weak anomalous signal. With the use of partial models and electron density maps in searches for anomalously scattering atoms, testing of alternative values of parameters and parallelized automated model-building, this method has the potential to extend the applicability of the SAD method in challenging cases.

  9. Hitomi X-ray observation of the pulsar wind nebula G21.5-0.9

    Science.gov (United States)

    Aharonian, Felix; Akamatsu, Hiroki; Akimoto, Fumie; Allen, Steven W.; Angelini, Lorella; Audard, Marc; Awaki, Hisamitsu; Axelsson, Magnus; Bamba, Aya; Bautz, Marshall W.; Blandford, Roger; Brenneman, Laura W.; Brown, Gregory V.; Bulbul, Esra; Cackett, Edward M.; Chernyakova, Maria; Chiao, Meng P.; Coppi, Paolo S.; Costantini, Elisa; de Plaa, Jelle; de Vries, Cor P.; den Herder, Jan-Willem; Done, Chris; Dotani, Tadayasu; Ebisawa, Ken; Eckart, Megan E.; Enoto, Teruaki; Ezoe, Yuichiro; Fabian, Andrew C.; Ferrigno, Carlo; Foster, Adam R.; Fujimoto, Ryuichi; Fukazawa, Yasushi; Furuzawa, Akihiro; Galeazzi, Massimiliano; Gallo, Luigi C.; Gandhi, Poshak; Giustini, Margherita; Goldwurm, Andrea; Gu, Liyi; Guainazzi, Matteo; Haba, Yoshito; Hagino, Kouichi; Hamaguchi, Kenji; Harrus, Ilana M.; Hatsukade, Isamu; Hayashi, Katsuhiro; Hayashi, Takayuki; Hayashida, Kiyoshi; Hiraga, Junko S.; Hornschemeier, Ann; Hoshino, Akio; Hughes, John P.; Ichinohe, Yuto; Iizuka, Ryo; Inoue, Hajime; Inoue, Yoshiyuki; Ishida, Manabu; Ishikawa, Kumi; Ishisaki, Yoshitaka; Iwai, Masachika; Kaastra, Jelle; Kallman, Tim; Kamae, Tsuneyoshi; Kataoka, Jun; Katsuda, Satoru; Kawai, Nobuyuki; Kelley, Richard L.; Kilbourne, Caroline A.; Kitaguchi, Takao; Kitamoto, Shunji; Kitayama, Tetsu; Kohmura, Takayoshi; Kokubun, Motohide; Koyama, Katsuji; Koyama, Shu; Kretschmar, Peter; Krimm, Hans A.; Kubota, Aya; Kunieda, Hideyo; Laurent, Philippe; Lee, Shiu-Hang; Leutenegger, Maurice A.; Limousin, Olivier; Loewenstein, Michael; Long, Knox S.; Lumb, David; Madejski, Greg; Maeda, Yoshitomo; Maier, Daniel; Makishima, Kazuo; Markevitch, Maxim; Matsumoto, Hironori; Matsushita, Kyoko; McCammon, Dan; McNamara, Brian R.; Mehdipour, Missagh; Miller, Eric D.; Miller, Jon M.; Mineshige, Shin; Mitsuda, Kazuhisa; Mitsuishi, Ikuyuki; Miyazawa, Takuya; Mizuno, Tsunefumi; Mori, Hideyuki; Mori, Koji; Mukai, Koji; Murakami, Hiroshi; Mushotzky, Richard F.; Nakagawa, Takao; Nakajima, Hiroshi; Nakamori, Takeshi; Nakashima, Shinya; Nakazawa, Kazuhiro; Nobukawa, Kumiko K.; Nobukawa, Masayoshi; Noda, Hirofumi; Odaka, Hirokazu; Ohashi, Takaya; Ohno, Masanori; Okajima, Takashi; Ota, Naomi; Ozaki, Masanobu; Paerels, Frits; Paltani, Stéphane; Petre, Robert; Pinto, Ciro; Porter, Frederick S.; Pottschmidt, Katja; Reynolds, Christopher S.; Safi-Harb, Samar; Saito, Shinya; Sakai, Kazuhiro; Sasaki, Toru; Sato, Goro; Sato, Kosuke; Sato, Rie; Sawada, Makoto; Schartel, Norbert; Serlemtsos, Peter J.; Seta, Hiromi; Shidatsu, Megumi; Simionescu, Aurora; Smith, Randall K.; Soong, Yang; Stawarz, Łukasz; Sugawara, Yasuharu; Sugita, Satoshi; Szymkowiak, Andrew; Tajima, Hiroyasu; Takahashi, Hiromitsu; Takahashi, Tadayuki; Takeda, Shin'ichiro; Takei, Yoh; Tamagawa, Toru; Tamura, Takayuki; Tanaka, Takaaki; Tanaka, Yasuo; Tanaka, Yasuyuki T.; Tashiro, Makoto S.; Tawara, Yuzuru; Terada, Yukikatsu; Terashima, Yuichi; Tombesi, Francesco; Tomida, Hiroshi; Tsuboi, Yohko; Tsujimoto, Masahiro; Tsunemi, Hiroshi; Tsuru, Takeshi Go; Uchida, Hiroyuki; Uchiyama, Hideki; Uchiyama, Yasunobu; Ueda, Shutaro; Ueda, Yoshihiro; Uno, Shin'ichiro; Urry, C. Megan; Ursino, Eugenio; Watanabe, Shin; Werner, Norbert; Wilkins, Dan R.; Williams, Brian J.; Yamada, Shinya; Yamaguchi, Hiroya; Yamaoka, Kazutaka; Yamasaki, Noriko Y.; Yamauchi, Makoto; Yamauchi, Shigeo; Yaqoob, Tahir; Yatsu, Yoichi; Yonetoku, Daisuke; Zhuravleva, Irina; Zoghbi, Abderahmen; Sato, Toshiki; Nakaniwa, Nozomu; Murakami, Hiroaki; Guest, Benson

    2018-04-01

    We present results from the Hitomi X-ray observation of a young composite-type supernova remnant (SNR) G21.5-0.9, whose emission is dominated by the pulsar wind nebula (PWN) contribution. The X-ray spectra in the 0.8-80 keV range obtained with the Soft X-ray Spectrometer (SXS), Soft X-ray Imager, and Hard X-ray Imager (HXI) show a significant break in the continuum as previously found with the NuSTAR observation. After taking into account all known emissions from the SNR other than the PWN itself, we find that the Hitomi spectra can be fitted with a broken power law with photon indices of Γ1 = 1.74 ± 0.02 and Γ2 = 2.14 ± 0.01 below and above the break at 7.1 ± 0.3 keV, which is significantly lower than the NuSTAR result (˜9.0 keV). The spectral break cannot be reproduced by time-dependent particle injection one-zone spectral energy distribution models, which strongly indicates that a more complex emission model is needed, as suggested by recent theoretical models. We also search for narrow emission or absorption lines with the SXS, and perform a timing analysis of PSR J1833-1034 with the HXI and the Soft Gamma-ray Detector. No significant pulsation is found from the pulsar. However, unexpectedly, narrow absorption line features are detected in the SXS data at 4.2345 keV and 9.296 keV with a significance of 3.65 σ. While the origin of these features is not understood, their mere detection opens up a new field of research and was only possible with the high resolution, sensitivity, and ability to measure extended sources provided by an X-ray microcalorimeter.

  10. Monitoring and Discovering X-ray Pulsars in the Small Magellanic Cloud

    International Nuclear Information System (INIS)

    Corbet, R.H.D.; Laycock, S.; Coe, M.J.; Marshall, F.E.; Markwardt, C.B.

    2004-01-01

    Regular monitoring of the SMC with RXTE has revealed a huge number of X-ray pulsars. Together with discoveries from other satellites at least 45 SMC pulsars are now known. One of these sources, a pulsar with a period of approximately 7.8 seconds, was first detected in early 2002 and since discovery it has been found to be in outburst nine times. The outburst pattern clearly shows a period of 45.1 ± 0.4 d which is thought to be the orbital period of this system. Candidate outburst periods have also been obtained for nine other pulsars and continued monitoring will enable us to confirm these. This large number of pulsars, all located at approximately the same distance, enables a wealth of comparative studies. In addition, the large number of pulsars found (which vastly exceeds the number expected simply by scaling the relative mass of the SMC and the Galaxy) reveals the recent star formation history of the SMC which has been influenced by encounters with both the LMC and the Galaxy

  11. A New Model for Thermal and Bulk Comptonization in Accretion-Powered X-ray Pulsars

    Science.gov (United States)

    Becker, Peter A.; Wolff, Michael T.

    2018-01-01

    The theory of spectral formation in accretion-powered X-ray pulsars has advanced considerably in the past decade, with the development of new models for the continuum and the cyclotron line formation processes. In many sources, the cyclotron line centroid energy is observed to vary as a function of source luminosity (and therefore accretion rate). In some cases, the variations in the luminosity seem to indicate a change in the structure of the accretion column, as the source passes from the sub-critical to the super-critical regime. With the recent launches of NuSTAR and NICER, observations of accreting X-ray pulsars are entering a new era, with large effective areas, broadband energy coverage, and good temporal resolution. These observations are already presenting new challenges to the theory, requiring the development of a new generation of more sophisticated physical models. In this paper, we discuss an improved model for bulk and thermal Comptonization in X-ray pulsars that will allow greater self-consistency in the data analysis process than current models, leading to more rigorous determinations of source parameters such as magnetic field strength, temperature, etc. The model improvements include (1) a more realistic geometry for the accretion column; (2) a more rigorous accretion velocity profile that merges smoothly with Newtonian free-fall as r → ∞ and (3) a more realistic free-streaming radiative boundary condition at the top of the column. This latter improvement means that we can now compute the pencil and fan beam components separately, which is necessary in order to analyze phase-dependent spectral data. We discuss applications of the new model to Her X-1, LMC X-4, and Cen X-3, and also to the Be X-ray binary 4U 0115+63.

  12. Determination of X-ray anomalous scattering in silicon

    International Nuclear Information System (INIS)

    Cusatis, C.

    1987-01-01

    The linear attenuation coeficient for X-ray in silicon was measured with approximately 0,1% accuracy, for 6 diferent wavelenghts of caracteristic radiation. From these result the imaginary parts of the atomic scattering factors, for silicon and for those wavelenghts, were obtained with the same accuracy. The results are compared with the most recent published values. The proposed method to avoid Rayleigh scattering can be used for any type of ''perfect'' crystal. (author) [pt

  13. CHANDRA PHASE-RESOLVED X-RAY SPECTROSCOPY OF THE CRAB PULSAR

    International Nuclear Information System (INIS)

    Weisskopf, Martin C.; Tennant, Allyn F.; O'Dell, Stephen L.; Elsner, Ronald F.; Yakovlev, Dmitry G.; Harding, Alice; Zavlin, Vyacheslav E.; Becker, Werner

    2011-01-01

    We present a new study of the X-ray spectral properties of the Crab Pulsar. The superb angular resolution of the Chandra X-Ray Observatory enables distinguishing the pulsar from the surrounding nebulosity. Analysis of the spectrum as a function of pulse phase allows the least-biased measure of interstellar X-ray extinction due primarily to photoelectric absorption and secondarily to scattering by dust grains in the direction of the Crab Nebula. We modify previous findings that the line of sight to the Crab is underabundant in oxygen and provide measurements with improved accuracy and less bias. Using the abundances and cross sections from Wilms et al. we find [O/H] = (5.28 ± 0.28) × 10 –4 (4.9 × 10 –4 is solar abundance). We also measure for the first time the impact of scattering of flux out of the image by interstellar grains. We find τ scat = 0.147 ± 0.043. Analysis of the spectrum as a function of pulse phase also measures the X-ray spectral index even at pulse minimum—albeit with increasing statistical uncertainty. The spectral variations are, by and large, consistent with a sinusoidal variation. The only significant variation from the sinusoid occurs over the same phase range as some rather abrupt behavior in the optical polarization magnitude and position angle. We also compare these spectral variations to those observed in gamma-rays and conclude that our measurements are both a challenge and a guide to future modeling and will thus eventually help us understand pair cascade processes in pulsar magnetospheres. The data are also used to set new, and less biased, upper limits to the surface temperature of the neutron star for different models of the neutron star atmosphere. We discuss how such data are best connected to theoretical models of neutron star cooling and neutron star interiors. The data restrict the neutrino emission rate in the pulsar core and the amount of light elements in the heat-blanketing envelope. The observations allow the

  14. Perspectives on Ultraluminous X-ray sources after the discovery of Ultraluminous Pulsars

    Science.gov (United States)

    Zampieri, L.; Ambrosi, E.; Fiore, A.; Pintore, F.; Turolla, R.; Israel, GL.; Stella, L.; Casella, P.; Papitto, A.; Rodriguez Castillo, G. A.; De Luca, A.; Tiengo, A.; Belfiore, A.; Esposito, P.; Marelli, M.; Novara, G.; Salvaterra, R.; Salvetti, D.; Mereghetti, S.; Wolter, A.

    2017-10-01

    Ultraluminous X-ray sources (ULXs) are observationally defined as non-nuclear extragalactic X-ray point sources with inferred (isotropic) luminosity exceeding the Eddington limit for a ˜ 10 M_{⊙} compact object. While in the past few years a certain evidence (and a general consensus) has been gathered in favour of the existence of black hole (BH) remnants in ULXs, the recent discovery of three Ultraluminous X-ray Pulsars has unexpectedly revealed what is likely to be a significant population of neutron star (NS) ULXs. These findings challenge more than ever our present understanding of these sources, their accretion mechanism/history, and their formation pathways. After reviewing some of these intriguing observational facts, we will summarize some perspective studies that we are carrying out to model the multiwavelength variability and broadband spectra of ULXs, including the contribution of an accretion column for NS systems. We derive the luminosity emitted by the latter assuming that a multipolar component dominates the magnetic field close to the NS. The focus is on comparing the simulated multiwavelength emission properties of stellar-mass/massive BHs to those of NS systems, and on confronting the model predictions with the available observations of Pulsar ULXs.

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

    Directory of Open Access Journals (Sweden)

    Mushtukov A. A.

    2014-01-01

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

  16. X-ray Pulsars Across the Parameter Space of Luminosity, Accretion Mode, and Spin

    Science.gov (United States)

    Laycock, Silas

    We propose to expand the scope of our successful project providing a multi-satellite library of X-ray Pulsar observations to the community. The library provides high-level products, activity monitoring, pulse-profiles, phased event files, spectra, and a unique pulse-profile modeling interface. The library's scientific footprint will expand in 4 key directions: (1) Update, by processing all new XMM-Newton and Chandra observations (2015-2017) of X-ray Binary Pulsars in the Magellanic Clouds. (2) Expand, by including all archival Suzaku, Swift and NuStar observations, and including Galactic pulsars. (3) Improve, by offering innovative data products that provide deeper insight. (4) Advance, by implementing a new generation of physically motivated emission and pulse-profile models. The library currently includes some 2000 individual RXTE-PCA, 200 Chandra ACIS-I, and 120 XMM-PN observations of the SMC spanning 15 years, creating an unrivaled record of pulsar temporal behavior. In Phase-2, additional observations of SMC pulsars will be added: 221 Chandra (ACIS-S and ACIS-I), 22 XMM-PN, 142 XMM-MOS, 92 Suzaku, 25 NuSTAR, and >10,000 Swift; leveraging our pipeline and analysis techniques already developed. With the addition of 7 Galactic pulsars each having many hundred multisatellite observations, these datasets cover the entire range of variability timescales and accretion regimes. We will model the pulse-profiles using state of the art techniques to parameterize their morphology and obtain the distribution of offsets between magnetic and spin axes, and create samples of profiles under specific accretion modes (whether pencil-beam or fan-beam dominated). These products are needed for the next generation of advances in neutron star theory and modeling. The long-duration of the dataset and “whole-galaxy" nature of the SMC sample make possible a new statistical approach to uncover the duty-cycle distribution and hence population demographics of transient High Mass X-ray

  17. Scanning the Magnetized Accretion Column of X-ray Pulsars with Cyclotron Lines

    Science.gov (United States)

    Schönherr, Gabriele; Wilms, J.; Kretschmar, P.; Pottschmidt, K.; Rothschild, R.; Kreykenbohm, I.; MAGNET Collaboration

    2010-03-01

    The strongly magnetized accretion column of X-ray pulsars is still not understood in many aspects like, e.g., its basic geometry and physical parameters. Cyclotron Resonance Scattering Features (short: cyclotron lines) are now becoming a possible tool to tap this mystery. As they form due to scattering processes of X-ray photons with magnetically quantized electrons in the accreted plasma, a better physical understanding of their formation and shape along with direct comparisons to observational data allows to backtrack the physical parameters and magnetic field structure in the line-forming region. High-resolution spectra with todays’ and future instruments now allow for an in-depth analysis of their shapes, promising exciting progress. We discuss results based on our new modelling attempts, which link theoretical Monte Carlo simulations directly to observational findings.

  18. X-ray Pulsars Across the Parameter Space of Luminosity, Accretion Mode, and Spin

    Science.gov (United States)

    Laycock, Silas; Yang, Jun; Christodoulou, Dimitris; Coe, Malcolm; Cappallo, Rigel; Zezas, Andreas; Ho, Wynn C. G.; Hong, JaeSub; Fingerman, Samuel; Drake, Jeremy J.; Kretschmar, Peter; Antoniou, Vallia

    2017-08-01

    We present our multi-satellite library of X-ray Pulsar observations to the community, and highlight recent science results. Available at www.xraypulsars.space the library provides a range of high-level data products, including: activity histories, pulse-profiles, phased event files, and a unique pulse-profile modeling interface. The initial release (v1.0) contains some 15 years of RXTE-PCA, Chandra ACIS-I, and XMM-PN observations of the Small Magellanic Cloud, creating a valuable record of pulsar behavior. Our library is intended to enable new progress on fundamental NS parameters and accretion physics. The major motivations are (1) Assemble a large homogeneous sample to enable population statistics. This has so far been used to map the propeller transition, and explore the role of retrograde and pro-grade accretion disks. (2) Obtain pulse-profiles for the same pulsars on many different occasions, at different luminosities and states in order to break model degeneracies. This effort has led to preliminary measurements of the offsets between magnetic and spin axes. With the addition of other satellites, and Galactic pulsars, the library will cover the entire available range of luminosity, variability timescales and accretion regimes.

  19. Charge and orbital ordered states studied by using x-ray anomalous scattering terms

    CERN Document Server

    Nakao, H

    2002-01-01

    Recently, the studies utilizing anomalous scattering term of atomic scattering factor near absorption edge, so called x-ray anomalous scattering and resonant x-ray scattering, have been rapidly developed. This technique has especially contributed to the determination of the charge-orbital ordered structure in strongly correlated electron system. In this paper, we present the typical examples - the charge ordering of V sup 4 sup + and V sup 5 sup + in NaV sub 2 O sub 5 and the antiferro-quadrupole ordering (orbital ordering) of Ge sup 3 sup + ions in CeB sub 6 (author)

  20. Contrasting Behaviour from Two Be/X-ray Binary Pulsars: Insights into Differing Neutron Star Accretion Modes

    Science.gov (United States)

    Townsend, L. J.; Drave, S. P.; Hill, A. B.; Coe, M. J.; Corbet, R. H. D.; Bird, A. J.

    2013-01-01

    In this paper we present the identification of two periodic X-ray signals coming from the direction of the Small Magellanic Cloud (SMC). On detection with the Rossi X-ray Timing Explorer (RXTE), the 175.4 s and 85.4 s pulsations were considered to originate from new Be/X-ray binary (BeXRB) pulsars with unknown locations. Using rapid follow-up INTEGRAL and XMM-Newton observations, we show the first pulsar (designated SXP175) to be coincident with a candidate high-mass X-ray binary (HMXB) in the northern bar region of the SMC undergoing a small Type II outburst. The orbital period (87d) and spectral class (B0-B0.5IIIe) of this system are determined and presented here for the first time. The second pulsar is shown not to be new at all, but is consistent with being SXP91.1 - a pulsar discovered at the very beginning of the 13 year long RXTE key monitoring programme of the SMC. Whilst it is theoretically possible for accreting neutron stars to change spin period so dramatically over such a short time, the X-ray and optical data available for this source suggest this spin-up is continuous during long phases of X-ray quiescence, where accretion driven spin-up of the neutron star should be minimal.

  1. Autonomous orbit determination and its error analysis for deep space using X-ray pulsar

    International Nuclear Information System (INIS)

    Feng, Dongzhu; Yuan, Xiaoguang; Guo, Hehe; Wang, Xin

    2014-01-01

    Autonomous orbit determination (OD) is a complex process using filtering method to integrate observation and orbit dynamic model effectively and estimate the position and velocity of a spacecraft. As a novel technology for autonomous interplanetary OD, X-ray pulsar holds great promise for deep space exploration. The position and velocity of spacecraft should be estimated accurately during the OD process. However, under the same condition, the accuracy of OD can be greatly reduced by the error of the initial orbit value and the orbit mutation. To resolve this problem, we propose a novel OD method, which is based on the X-ray pulsar measurement and Adaptive Unscented Kalman Filter (AUKF). The accuracy of OD can be improved obviously because the AUKF estimates the orbit of spacecraft using measurement residual. During the simulation, the orbit of Phoenix Mars Lander, Deep Impact Probe, and Voyager 1 are selected. Compared with Unscented Kalman Filter (UKF) and Extended Kalman Filter (EKF), the simulation results demonstrate that the proposed OD method based on AUKF can accurately determinate the velocity and position and effectively decrease the orbit estimated errors which is caused by the orbit mutation and orbit initial errors. (authors)

  2. Discovery of a new accreting millisecond X-ray pulsar in the globular cluster NGC 2808

    Science.gov (United States)

    Sanna, A.; Papitto, A.; Burderi, L.; Bozzo, E.; Riggio, A.; Di Salvo, T.; Ferrigno, C.; Rea, N.; Iaria, R.

    2017-02-01

    We report on the discovery of coherent pulsations at a period of 2.9 ms from the X-ray transient MAXI J0911-655 in the globular cluster NGC 2808. We observed X-ray pulsations at a frequency of 339.97 Hz in three different observations of the source performed with XMM-Newton and NuSTAR during the source outburst. This newly discovered accreting millisecond pulsar is part of an ultra-compact binary system characterised by an orbital period of 44.3 min and a projected semi-major axis of 17.6 lt-ms. Based on the mass function, we estimate a minimum companion mass of 0.024 M⊙, which assumes a neutron star mass of 1.4 M⊙ and a maximum inclination angle of 75° (derived from the lack of eclipses and dips in the light-curve of the source). We find that the Roche-lobe of the companion star could either be filled by a hot (5 × 106 K) pure helium white dwarf with a 0.028 M⊙ mass (implying I ≃ 58°) or an old (>5 Gyr) brown dwarf with metallicity abundances between solar/sub-solar and mass ranging in the interval 0.065 to 0.085 (16 < I < 21). During the outburst, the broad-band energy spectra are well described by a superposition of a weak black-body component (kT 0.5 keV) and a hard cut-off power-law with photon index Γ 1.7 and cut-off at a temperature kTe 130 keV. Up until the latest Swift-XRT observation performed on 19th July, 2016, the source had been observed in outburst for almost 150 days, which makes MAXI J0911-655 the second accreting millisecond X-ray pulsar with outburst duration longer than 100 days.

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

    Energy Technology Data Exchange (ETDEWEB)

    West, Brent F. [Department of Electrical and Computer Engineering, United States Naval Academy, Annapolis, MD (United States); Wolfram, Kenneth D. [Naval Research Laboratory (retired), Washington, DC (United States); Becker, Peter A., E-mail: bwest@usna.edu, E-mail: kswolfram@gmail.com, E-mail: pbecker@gmu.edu [Department of Physics and Astronomy, George Mason University, Fairfax, VA (United States)

    2017-02-01

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

  4. Future X-ray Polarimetry of Relativistic Accelerators: Pulsar Wind Nebulae and Supernova Remnants

    Directory of Open Access Journals (Sweden)

    Niccolò Bucciantini

    2018-03-01

    Full Text Available Supernova remnants (SNRs and pulsar wind nebulae (PWNs are among the most significant sources of non-thermal X-rays in the sky, and the best means by which relativistic plasma dynamics and particle acceleration can be investigated. Being strong synchrotron emitters, they are ideal candidates for X-ray polarimetry, and indeed the Crab nebula is up to present the only object where X-ray polarization has been detected with a high level of significance. Future polarimetric measures will likely provide us with crucial information on the level of turbulence that is expected at particle acceleration sites, together with the spatial and temporal coherence of magnetic field geometry, enabling us to set stronger constraints on our acceleration models. PWNs will also allow us to estimate the level of internal dissipation. I will briefly review the current knowledge on the polarization signatures in SNRs and PWNs, and I will illustrate what we can hope to achieve with future missions such as IXPE/XIPE.

  5. On the morphology of outbursts of accreting millisecond X-ray pulsar Aquila X-1

    Science.gov (United States)

    Güngör, C.; Ekşi, K. Y.; Göğüş, E.

    2017-10-01

    We present the X-ray light curves of the last two outbursts - 2014 & 2016 - of the well known accreting millisecond X-ray pulsar (AMXP) Aquila X-1 using the monitor of all sky X-ray image (MAXI) observations in the 2-20 keV band. After calibrating the MAXI count rates to the all-sky monitor (ASM) level, we report that the 2016 outburst is the most energetic event of Aql X-1, ever observed from this source. We show that 2016 outburst is a member of the long-high class according to the classification presented by Güngör et al. with ˜ 68 cnt/s maximum flux and ˜ 60 days duration time and the previous outburst, 2014, belongs to the short-low class with ˜ 25 cnt/s maximum flux and ˜ 30 days duration time. In order to understand differences between outbursts, we investigate the possible dependence of the peak intensity to the quiescent duration leading to the outburst and find that the outbursts following longer quiescent episodes tend to reach higher peak energetic.

  6. IGR J17062–6143 Is an Accreting Millisecond X-Ray Pulsar

    Energy Technology Data Exchange (ETDEWEB)

    Strohmayer, Tod [Astrophysics Science Division and Joint Space-Science Institute, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Keek, Laurens [X-ray Astrophysics Laboratory, NASA/GSFC and CRESST and the Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)

    2017-02-20

    We present the discovery of 163.65 Hz X-ray pulsations from IGR J17062−6143 in the only observation obtained from the source with the Rossi X-ray Timing Explorer . This detection makes IGR J17062−6143 the lowest-frequency accreting millisecond X-ray pulsar presently known. The pulsations are detected in the 2–12 keV band with an overall significance of 4.3 σ and an observed pulsed amplitude of 5.54% ± 0.67% (in this band). Both dynamic power spectral and coherent phase timing analysis indicate that the pulsation frequency is decreasing during the ≈1.2 ks observation in a manner consistent with orbital motion of the neutron star. Because the observation interval is short, we cannot precisely measure the orbital period; however, periods shorter than 17 minutes are excluded at 90% confidence. For the range of acceptable circular orbits the inferred binary mass function substantially overlaps the observed range for the AMXP population as a whole.

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

    International Nuclear Information System (INIS)

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

    1998-01-01

    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

  8. X-Rays from the Nearby Solitary Millisecond Pulsar PSR J0030+0451 - the Final ROSAT Observations

    CERN Document Server

    Becker, W; Bäcker, A N; Lommen, D; Becker, Werner; Tr"umper, Joachim; Backer, Andrea N.Lommen & Donald C.

    2000-01-01

    We report on X-ray observations of the solitary 4.8 ms pulsar PSR J0030+0451. The pulsar was one of the last targets observed in DEC-98 by the ROSAT PSPC. X-ray pulses are detected on a $4.5\\sigma$ level and make the source the $11^{th}$ millisecond pulsar detected in the X-ray domain. The pulsed fraction is found to be $69\\pm18%$. The X-ray pulse profile is characterized by two narrow peaks which match the gross pulse profile observed at 1.4 GHz. Assuming a Crab-like spectrum the X-ray flux is in the range $f_x= 2-3\\times 10^{-13}$ erg s$^{-1}$ cm$^{-2} $ ($0.1-2.4$ keV), implying an X-ray efficiency of $L_x/\\dot{E}\\sim 0.5-5 \\times 10^{-3} (d/0.23 {kpc})^2$.

  9. A multiwavelength study of SXP 1062, the long-period X-ray pulsar associated with a supernova remnant

    Science.gov (United States)

    González-Galán, A.; Oskinova, L. M.; Popov, S. B.; Haberl, F.; Kühnel, M.; Gallagher, J.; Schurch, M. P. E.; Guerrero, M. A.

    2018-04-01

    SXP 1062 is a Be X-ray binary (BeXB) located in the Small Magellanic Cloud. It hosts a long-period X-ray pulsar and is likely associated with the supernova remnant MCSNR J0127-7332. In this work we present a multiwavelength view on SXP 1062 in different luminosity regimes. We consider monitoring campaigns in optical (OGLE survey) and X-ray (Swift telescope). During these campaigns a tight coincidence of X-ray and optical outbursts is observed. We interpret this as typical Type I outbursts as often detected in BeXBs at periastron passage of the neutron star (NS). To study different X-ray luminosity regimes in depth, during the source quiescence we observed it with XMM-Newton while Chandra observations followed an X-ray outburst. Nearly simultaneously with Chandra observations in X-rays, in optical the RSS/SALT telescope obtained spectra of SXP 1062. On the basis of our multiwavelength campaign we propose a simple scenario where the disc of the Be star is observed face-on, while the orbit of the NS is inclined with respect to the disc. According to the model of quasi-spherical settling accretion our estimation of the magnetic field of the pulsar in SXP 1062 does not require an extremely strong magnetic field at the present time.

  10. CubeX: The CubeSAT X-ray Telescope for Elemental Abundance Mapping of Airless Bodies and X-ray Pulsar Navigation

    Science.gov (United States)

    Nittler, L. R.; Hong, J.; Kenter, A.; Romaine, S.; Allen, B.; Kraft, R.; Masterson, R.; Elvis, M.; Gendreau, K.; Crawford, I.; Binzel, R.; Boynton, W. V.; Grindlay, J.; Ramsey, B.

    2017-12-01

    The surface elemental composition of a planetary body provides crucial information about its origin, geological evolution, and surface processing, all of which can in turn provide information about solar system evolution as a whole. Remote sensing X-ray fluorescence (XRF) spectroscopy has been used successfully to probe the major-element compositions of airless bodies in the inner solar system, including the Moon, near-Earth asteroids, and Mercury. The CubeSAT X-ray Telescope (CubeX) is a concept for a 6U planetary X-ray telescope (36U with S/C), which utilizes Miniature Wolter-I X-ray optics (MiXO), monolithic CMOS and SDD X-ray sensors for the focal plane, and a Solar X-ray Monitor (heritage from the REXIS XRF instrument on NASA's OSIRIS-REx mission). CubeX will map the surface elemental composition of diverse airless bodies by spectral measurement of XRF excited by solar X-rays. The lightweight ( 1 kg) MiXO optics provide sub-arcminute resolution with low background, while the inherently rad-hard CMOS detectors provide improved spectral resolution ( 150 eV) at 0 °C. CubeX will also demonstrate X-ray pulsar timing based deep space navigation (XNAV). Successful XNAV will enable autonomous deep navigation with little to no support from the Deep Space Network, hence lowering the operation cost for many more planetary missions. Recently selected by NASA Planetary Science Deep Space SmallSat Studies, the first CubeX concept, designed to rideshare to the Moon as a secondary spacecraft on a primary mission, is under study in collaboration with the Mission Design Center at NASA Ames Research Center. From high altitude ( 6,000 km) frozen polar circular orbits, CubeX will study > 8 regions ( 110 km) of geological interest on the Moon over one year to produce a high resolution ( 2-3 km) elemental abundance map of each region. The novel focal plane design of CubeX also allows us to evaluate the performance of absolute navigation by sequential observations of several

  11. Nustar Detection of Hard X-Ray Phase Lags from the Accreting Pulsar GS 0834-430

    DEFF Research Database (Denmark)

    Miyasaka, Hiromasa; Bachetti, Matteo; Harrison, Fiona A.

    2013-01-01

    -mass X-ray binary pulsars. Previously reported lags have been significantly smaller in phase and restricted to low energies (E mechanisms that might produce this energy-dependent pulse phase shift. We find the most likely explanation for this effect is a complex beam...

  12. A curious case of the accretion-powered X-ray pulsar GX 1+4

    Science.gov (United States)

    Jaisawal, Gaurava K.; Naik, Sachindra; Gupta, Shivangi; Chenevez, Jérôme; Epili, Prahlad

    2018-04-01

    We present detailed spectral and timing studies using a NuSTAR observation of GX 1+4 in October 2015 during an intermediate intensity state. The measured spin period of 176.778 s is found to be one of the highest values since its discovery. In contrast to a broad sinusoidal-like pulse profile, a peculiar sharp peak is observed in profiles below ˜25 keV. The profiles at higher energies are found to be significantly phase-shifted compared to the soft X-ray profiles. Broadband energy spectra of GX 1+4, obtained from NuSTAR and Swift observations, are described with various continuum models. Among these, a two component model consisting of a bremsstrahlung and a blackbody component is found to best-fit the phase-averaged and phase-resolved spectra. Physical models are also used to investigate the emission mechanism in the pulsar, which allows us to estimate the magnetic field strength to be in ˜(5-10)× 1012 G range. Phase-resolved spectroscopy of NuSTAR observation shows a strong blackbody emission component in a narrow pulse phase range. This component is interpreted as the origin of the peculiar peak in the pulse profiles below ≤25 keV. The size of emitting region is calculated to be ˜400 m. The bremsstrahlung component is found to dominate in hard X-rays and explains the nature of simple profiles at high energies.

  13. Light curve and pulse profile of the x-ray pulsar Vela X-1

    International Nuclear Information System (INIS)

    Nagase, Fumiaki; Hayakawa, Satio; Makino, Fumiyoshi; Sato, Naohisa; Makishima, Kazuo.

    1983-01-01

    The following properties of the X-ray binary pulsar Vela X-1 are presented by reference to its observations in March 1980. The light curve shows a high state and a low state in the first and second halves of an orbital period, respectively, but they may rather be defined as a soft state and hard state, respectively, since the intensity above 9 keV does not appreciably change between these two states. The energy spectra in these states indicate the presence of circumstellar absorption. The pulse profiles at high (9-22 keV) and low (1-9 keV) energies are different, indicating the absorption by cold matter which is probably in the accretion column. The absorber which is responsible for the soft and hard states is attributed to the stellar wind whose flow pattern is consistent with that obtained from optical absorption spectra. The orbital period is obtained by a combined analysis of X-ray data since 1972. No appreciable change of the period gives a constraint on the dynamical behavior of the binary system. (author)

  14. Two populations of X-ray pulsars produced by two types of supernova.

    Science.gov (United States)

    Knigge, Christian; Coe, Malcolm J; Podsiadlowski, Philipp

    2011-11-09

    Two types of supernova are thought to produce the overwhelming majority of neutron stars in the Universe. The first type, iron-core-collapse supernovae, occurs when a high-mass star develops a degenerate iron core that exceeds the Chandrasekhar limit. The second type, electron-capture supernovae, is associated with the collapse of a lower-mass oxygen-neon-magnesium core as it loses pressure support owing to the sudden capture of electrons by neon and/or magnesium nuclei. It has hitherto been impossible to identify the two distinct families of neutron stars produced in these formation channels. Here we report that a large, well-known class of neutron-star-hosting X-ray pulsars is actually composed of two distinct subpopulations with different characteristic spin periods, orbital periods and orbital eccentricities. This class, the Be/X-ray binaries, contains neutron stars that accrete material from a more massive companion star. The two subpopulations are most probably associated with the two distinct types of neutron-star-forming supernova, with electron-capture supernovae preferentially producing systems with short spin periods, short orbital periods and low eccentricities. Intriguingly, the split between the two subpopulations is clearest in the distribution of the logarithm of spin period, a result that had not been predicted and which still remains to be explained. © 2011 Macmillan Publishers Limited. All rights reserved

  15. Structure investigation of metal ions clustering in dehydrated gel using x-ray anomalous dispersion effect

    CERN Document Server

    Soejima, Y; Sugiyama, M; Annaka, M; Nakamura, A; Hiramatsu, N; Hara, K

    2003-01-01

    The structure of copper ion clusters in dehydrated N-isopropylacrylamide/sodium acrylate (NIPA/SA) gel has been studied by means of small angle X-ray scattering (SAXS) method. In order to distinguish the intensity scattered by Cu ions, the X-ray anomalous dispersion effect around the Cu K absorption edge has been coupled with SAXS. It is found that the dispersion effect dependent on the incident X-ray energy is remarkable only at the momentum transfer q = 0.031 A sup - sup 1 , where a SAXS peak is observed. The results indicate that copper ions form clusters in the dehydrated gel, and that the mean size of clusters is the same as that of SA clusters produced by microphase separation. It is therefore naturally presumed that copper ions are adsorbed into the SA molecules. On the basis of the presumption, a mechanism is proposed for microphase-separation and clustering of Cu ions.

  16. Phase-resolved X-ray polarimetry of the Crab pulsar with the AstroSat CZT Imager

    Science.gov (United States)

    Vadawale, S. V.; Chattopadhyay, T.; Mithun, N. P. S.; Rao, A. R.; Bhattacharya, D.; Vibhute, A.; Bhalerao, V. B.; Dewangan, G. C.; Misra, R.; Paul, B.; Basu, A.; Joshi, B. C.; Sreekumar, S.; Samuel, E.; Priya, P.; Vinod, P.; Seetha, S.

    2018-01-01

    The Crab pulsar is a typical example of a young, rapidly spinning, strongly magnetized neutron star that generates broadband electromagnetic radiation by accelerating charged particles to near light speeds in its magnetosphere1. Details of this emission process so far remain poorly understood. Measurement of polarization in X-rays, particularly as a function of pulse phase, is thought to be a key element necessary to unravel the mystery of pulsar radiation2-4. Such measurements are extremely difficult, however: to date, Crab is the only pulsar to have been detected in polarized X-rays5-8 and the measurements have not been sensitive enough to adequately reveal the variation of polarization characteristics across the pulse7. Here, we present the most sensitive measurement to date of polarized hard X-ray emission from the Crab pulsar and nebula in the 100-380 keV band, using the Cadmium-Zinc-Telluride Imager9 instrument on-board the Indian astronomy satellite AstroSat10. We confirm with high significance the earlier indication6,7 of a strongly polarized off-pulse emission. However, we also find a variation in polarization properties within the off-pulse region. In addition, our data hint at a swing of the polarization angle across the pulse peaks. This behaviour cannot be fully explained by the existing theoretical models of high-energy emission from pulsars.

  17. X-RAY EMISSION FROM J1446–4701, J1311–3430, AND OTHER BLACK WIDOW PULSARS

    Energy Technology Data Exchange (ETDEWEB)

    Arumugasamy, Prakash; Pavlov, George G. [Department of Astronomy and Astrophysics, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16802 (United States); Garmire, Gordon P., E-mail: pxa151@ucs.psu.edu [Huntingdon Institute for X-ray Astronomy, LLC, 10677 Franks Road, Huntingdon, PA 16652 (United States)

    2015-12-01

    We present the results of detailed X-ray analysis of two black-widow pulsars (BWPs), J1446–4701 and J1311–3430. PSR J1446–4701 is a BWP with orbital parameters near the median values of the sample of known BWPs. Its X-ray emission that was detected by XMM-Newton is well characterized by a soft power-law (PL) spectrum (photon index Γ ≈ 3), and it shows no significant orbital modulations. In view of a lack of radio eclipses and an optical non-detection, the system most likely has a low orbital inclination. PSR J1311–3430 is an extreme BWP with a very compact orbit and the lowest minimum mass companion. Our Chandra data confirm the hard Γ ≈ 1.3 emission seen in previous observations. Through phase-restricted spectral analysis, we found a hint (∼2.6σ) of spectral hardening around pulsar inferior conjunction. We also provide a uniform analysis of the 12 BWPs observed with Chandra and compare their X-ray properties. Pulsars with soft, Γ > 2.5 emission seem to have lower than average X-ray and γ-ray luminosities. We do not, however, see any other prominent correlation between the pulsar’s X-ray emission characteristics and any of its other properties. The contribution of the intra-binary shock to the total X-ray emission, if any, is not discernible in this sample of pulsars with shallow observations.

  18. Amorphous CuZr alloy investigated by anomalous X-ray scattering

    International Nuclear Information System (INIS)

    Bionducci, M.; Buffa, F.; Licheri, G.; Navarra, G.

    1993-01-01

    Cu Zr amorphous powder was prepared by a mechano-chemical reaction in order to state a comparison with corresponding samples prepared by different amorphization processes. The structure of the alloyed powder is studied by anomalous X-ray scattering method. Starting from a suitable set of total and differential structure factors and using a regularization algorithm, a set of partial structure factors is obtained, which compares well with those previously obtained for a sample prepared by rapid solidification of the melt. (authors) 1 fig., 1 tab., 14 refs

  19. Suzaku observation of the eclipsing high mass X-ray binary pulsar ...

    Indian Academy of Sciences (India)

    Jincy Devasia

    2018-02-09

    Feb 9, 2018 ... The correlated variations in the spectral parameters indicate towards the presence of clumps in the stellar wind of the companion star accounting for the absorption of low energy X-rays in some time segments. Keywords. X-ray: neutron stars—X-ray binaries: individual (XTE J1855-026). 1. Introduction.

  20. New outburst of the accreting millisecond X-ray pulsar NGC 6440 X-2 and discovery of a strong 1 Hz modulation in the light-curve

    NARCIS (Netherlands)

    Patruno, A.; Yang, Y.; Altamirano, D.; Armas-Padilla, M.; Cavecchi, Y.; Degenaar, N.; Kalamkar, M.; Kaur, R.; Klis, M. Van Der; Watts, A.; Wijnands, R.; Linares, M.; Casella, P.; Rea, N.; Soleri, P.; Markwardt, C.; Strohmayer, T.; Heinke, C.

    On June 11th, 2010, RXTE/PCA galactic bulge scan observations showed an increase in activity from the globular cluster NGC 6440. Two accreting millisecond X-ray pulsars (AMXPs) and 22 other X-ray binaries are known in NGC 6440 (see Pooley et al. 2002, ApJ 573, 184, Altarmirano et al. 2010, ApJL 712,

  1. A gradient method for anomalous small-angle x-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Jemian, P.R. [Argonne National Lab., IL (United States); Weertman, J.R. [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering; Long, G.G. [National Institute of Standards and Technology, Gaithersburg, MD (United States). Ceramics Div.

    1992-09-15

    A new method of general applicability for analyzing data from anomalous dispersion small-angle X-ray scattering (ASAXS) measurements is described. ASAXS is used as a contrast variation method to label the scattering from a single element in a complex material containing several types of scatterers. The contrast variation is achieved through the anomalous dispersion of X-rays. Thus only one sample is required for a complete analysis. To label a scatterer by ASAXS, the atomic scattering factor of an element in the sample is varied by the selection of photon energies near the absorption edge of the element. Careful selection of the photon energies allows the contrast of only the labeled scatterer to change. Data from several small-angle scattering measurements, each conducted at a fixed energy, are combined in a single analysis. The gradient method, used as an extension to a standard SAXS data analysis method, is demonstrated by isolating the volume fraction size distribution of Cr{sub 23}C{sub 6} in 9Cr-1 MoVNb steel.

  2. A Comprehensive Spectral Analysis of the X-Ray Pulsar 4U 1907+09 from Two Observations with the Suzaku X-Ray Observatory

    Science.gov (United States)

    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. Can a Bright and Energetic X-Ray Pulsar Be Hiding Amid the Debris of SN 1987A?

    Science.gov (United States)

    Esposito, Paolo; Rea, Nanda; Lazzati, Davide; Matsuura, Mikako; Perna, Rosalba; Pons, José A.

    2018-04-01

    The mass of the stellar precursor of supernova (SN) 1987A and the burst of neutrinos observed at the moment of the explosion are consistent with the core-collapse formation of a neutron star. However, no compelling evidence for the presence of a compact object of any kind in SN 1987A has been found yet in any band of the electromagnetic spectrum, prompting questions on whether the neutron star survived and, if it did, on its properties. Beginning with an analysis of recent Chandra observations, here we appraise the current observational situation. We derived limits on the X-ray luminosity of a compact object with a nonthermal, Crab-pulsar-like spectrum of the order of ≈(1–5) × 1035 erg s‑1, corresponding to limits on the rotational energy loss of a possible X-ray pulsar in SN 1987A of ≈(0.5–1.5) × 1038 erg s‑1. However, a much brighter X-ray source cannot be excluded if, as is likely, it is enshrouded in a cloud of absorbing matter with a metallicity similar to that expected in the outer layers of a massive star toward the end of its life. We found that other limits obtained from various arguments and observations in other energy ranges either are unbinding or allow a similar maximum luminosity of the order of ≈1035 erg s‑1. We conclude that while a pulsar alike the one in the Crab Nebula in both luminosity and spectrum is hardly compatible with the observations, there is ample space for an “ordinary” X-ray-emitting young neutron star, born with normal initial spin period, temperature, and magnetic field, to be hiding inside the evolving remnant of SN 1987A.

  4. The influence of the positronium photoionization rate on the polar cap X-ray luminosity of radio pulsars

    Science.gov (United States)

    Barsukov, D. P.; Vorontsov, M. V.

    2017-12-01

    The influence of the positronium photoionization rate on the polar cap X-ray luminosity of old radio pulsars is considered. It is assumed that the polar cap is heated only by reverse positrons accelerated in the pulsar diode. It is supposed that the pulsar diode is in a stationary state with the lower plate located near the star surface (polar cap model) occupies all the pulsar tube cross section and operates in the regime of steady space charge by the limited electron flow. The influence of a small-scale magnetic field on the electric field inside the pulsar diode is taken into account. The reverse positron current is calculated in the framework of two models: rapid and gradual screening. To calculate the production rate of electron-positron pairs we take into account only the curvature radiation of primary electrons and its absorption in the magnetic field. It is assumed that some fraction of electron-positron pairs is created in a bound state (positronium). Later, such positroniums are photoionized by thermal photons from the polar cap.

  5. X-Ray Analysis of the Proper Motion and Pulsar Wind Nebula for PSR J1741-2054

    Science.gov (United States)

    Auchettl, Katie; Slane, Patrick; Romani, Roger W.; Posselt, Bettina; Pavlov, George G.; Kargaltsev, Oleg; Ng, C-Y.; Temim, Tea; Weisskopf, Martin C.; Bykov, Andrei; hide

    2015-01-01

    We obtained six observations of PSR J1741-2054 using the Chandra ACIS-S detector totaling approx.300 ks. By registering this new epoch of observations to an archival observation taken 3.2 yr earlier using X-ray point sources in the field of view, we have measured the pulsar proper motion at micron = 109 +/- 10 mas yr(exp. -1) in a direction consistent with the symmetry axis of the observed H(alpha) nebula. We investigated the inferred past trajectory of the pulsar but find no compelling association with OB associations in which the progenitor may have originated. We confirm previous measurements of the pulsar spectrum as an absorbed power law with photon index gamma = 2.68 +/- 0.04, plus a blackbody with an emission radius of (4.5(+3.2/-2.5))d(0.38) km, for a DM-estimated distance of 0.38d(0.38) kpc and a temperature of 61.7 +/- 3.0 eV. Emission from the compact nebula is well described by an absorbed power law model with a photon index of gamma = 1.67 +/- 0.06, while the diffuse emission seen as a trail extending northeast of the pulsar shows no evidence of synchrotron cooling. We also applied image deconvolution techniques to search for small-scale structures in the immediate vicinity of the pulsar, but found no conclusive evidence for such structures.

  6. NuSTAR detection of 4s Hard X-ray Lags from the Accreting Pulsar GS 0834-430

    Directory of Open Access Journals (Sweden)

    Bachetti Matteo

    2014-01-01

    Full Text Available The NuSTAR hard X-ray telescope observed the transient Be/X-ray binary GS 0834–430 during its 2012 outburst. The source is detected between 3 – 79 keV with high statistical significance, and we were able to perform very accurate spectral and timing analysis. The phase-averaged spectrum is consistent with that observed in many other magnetized accreting pulsars. We fail to detect cyclotron resonance scattering features in either phase-averaged nor phase-resolved spectra that would allow us to constrain the pulsar’s magnetic field. We detect a pulse period of ~ 12:29 s in all energy bands. The pulse profile can be modeled with a double Gaussian and shows a strong and smooth hard lag of up to 0.3 cycles in phase, or about 4s between the pulse at ~ 3 and ≳ 30 keV. This is the first report of such a strong lag in high-mass X-ray binary (HMXB pulsars. Previously reported lags have been significantly smaller in phase and restricted to low-energies (E<10 keV. We investigate the possible mechanisms that might produce such lags. We find the most likely explanation for this effect to be a complex beam geometry.

  7. Introduction to the application and limits of anomalous X-ray diffraction in the determination of partial structure factors

    International Nuclear Information System (INIS)

    Bienenstock, A.

    1993-01-01

    The use of anomalous X-ray scattering to obtain the first differences and partial structure factors normally obtained with isotopic substitution neutron diffraction is described and compared with the neutron technique. Both the problems associated with the X-ray technique (low-Z problems, scattering factor problems, Compton scattering problems, fluorescence problems, storage ring stability problems) and the situations in which it is highly valuable are discussed. 12 refs

  8. Vaporizing neutron stars in low-mass x-ray binaries and the statistics of millisecond pulsars

    Energy Technology Data Exchange (ETDEWEB)

    Tavani, M. (California Univ., Livermore, CA (United States). Inst. of Geophysics and Planetary Physics)

    1991-08-08

    Recent data on low-mass X-ray binaries (LMXBs) and msec pulsars (MSPs) pose a challenge to evolutionary which neglect the effects of disk and companion irradiation. Here we discuss the main features of a radiation-driven (RD) evolutionary model that may be applicable to several LMXBs. According to this model, irradiation from the accreting compact star LMXBs vaporizes'' the accretion disk and the companion star by driving a self-sustained mass loss until a sudden accretion-turn of occurs. The main characteristics of the RD-evolution are: (1) the lifetime of RD-LMXB's is of order 10{sup 7} years or less: (2) both the orbital period gap and the X-ray luminosity may be consequences of RD-evolution of LMXB's containing lower main sequence and degenerate companion stars; (3) the companion star may transfer mass to the primary even if it underfills its Roche lobe; (4) the recycled msec pulsar can continue to vaporize the low-mass companion star even after the accretion turn-off produced by a strong pulsar wind; (5) the RD-evolutionary model resolves the apparent statistical discrepancy between the number of MSP's and their LMXB progenitors. 14 refs., 1 fig., 1 tab.

  9. NuSTAR discovery of a cyclotron line in the accreting X-ray pulsar IGR J16393-4643

    DEFF Research Database (Denmark)

    Bodaghee, Arash; Tomsick, John A.; Fornasini, Francesca A.

    2016-01-01

    The high-mass X-ray binary and accreting X-ray pulsar IGR J16393-4643 was observed by NuSTAR in the 3-79 keV energy band for a net exposure time of 50ks. We present the results of this observation which enabled the discovery of acyclotron resonant scattering feature with a centroid energy of 29.......3(+1.1/-1.3)keV. This allowed us to measure the magnetic field strength of the neutron starfor the first time: B = (2.5+/-0.1) x1012 G. The known pulsation period is now observed at 904.0+/-0.1 s. Since 2006, the neutron star has undergone along-term spin-up trend at a rate of P' = -2x10-8 s/s-1 (-0.6 s per year...

  10. Suzaku observation of the eclipsing high mass X-ray binary pulsar XTE J1855-026

    Science.gov (United States)

    Devasia, Jincy; Paul, Biswajit

    2018-02-01

    We report results from analysis performed on an eclipsing supergiant high mass X-ray binary pulsar XTE J1855-026 observed with the X-ray Imaging Spectrometer (XIS) on-board Suzaku Observatory in April 2015. Suzaku observed this source for a total effective exposure of ˜ 87 ks just before an eclipse. Pulsations are clearly observed and the pulse profiles of XTE J1855-026 did not show significant energy dependence during this observation consistent with previous reports. The time averaged energy spectrum of XTE J1855-026 in the 1.0-10.5 keV energy range can be well fitted with a partial covering power law model modified with interstellar absorption along with a black-body component for soft excess and a gaussian for iron fluorescence line emision. The hardness ratio evolution during this observation indicated significant absorption of soft X-rays in some segments of the observation. For better understanding of the reason behind this, we performed time-resolved spectroscopy in the 2.5-10.5 keV energy band which revealed significant variations in the spectral parameters, especially the hydrogen column density and iron line equivalent width with flux. The correlated variations in the spectral parameters indicate towards the presence of clumps in the stellar wind of the companion star accounting for the absorption of low energy X-rays in some time segments.

  11. Anomalous small-angle x-ray scattering of a femtosecond irradiated germano silicate fibre preform.

    Energy Technology Data Exchange (ETDEWEB)

    Hindle, F.; Fertein, E.; Seifert, S.; Przygodski, C.S.; Bocquet, R.; Douay, M.; Bychkov, E.; Experimental Facilities Division (APS); LPCA, CNRS; PhLAM; Univ. des Sciences et Tech. de Lille

    2005-01-01

    RADIATION is shown to induce significant mesoscopic structure. The scattering intensity for irradiated glasses is close to two orders of magnitude greater than that of unexposed material. Anomalous small-angle X-ray scattering (ASAXS) around the germanium K-edge for the silica and germanium doped silica regions of a fiber preform is used to demonstrate that identical structures are induced in both glass materials, with germanium displaying a capacity to isomorphically replace silicon in the case of the germanium doped silica. Analysis of measured scattering indicates that photo-inscribed features are produced at two distinct scales with typical radii of R {approx} 20 Angstroms and R{sub min} {approx} 200 Angstroms.

  12. Anomalous small-angle X-ray scattering from charged soft matter

    Science.gov (United States)

    Sztucki, M.; Di Cola, E.; Narayanan, T.

    2012-06-01

    A review of recent applications of Anomalous Small-Angle X-ray Scattering (ASAXS) to charged soft matter systems is presented. Although the potential of ASAXS was realized in the eighties [1], applications to soft matter systems became feasible in recent years thanks to the technical developments at the synchrotron sources. Examples include both stiff chain and flexible polyelectrolytes, colloidal brush-like polyelectrolytes, DNA, RNA, and polysaccharides where the counterion profile could be determined with high precision and compared with theoretical models. In addition, ASAXS has also been found useful for microstructure characterization in soft materials. Finally, the present capability for ASAXS studies is illustrated by an example involving a surfactant micellar system.

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    We present broadband (3-78 keV) NuSTAR X-ray imaging and spectroscopy of the Crab nebula and pulsar. We show that while the phase-averaged and spatially integrated nebula + pulsar spectrum is a power law in this energy band, spatially resolved spectroscopy of the nebula finds a break at ~9 ke...... and measure the size of the nebula as a function of energy in seven bands. These results find that the rate of shrinkage with energy of the torus size can be fitted by a power law with an index of γ = 0.094 ± 0.018, consistent with the predictions of Kennel and Coroniti. The change in size is more rapid...

  14. General Relativistic Radiation MHD Simulations of Supercritical Accretion onto a Magnetized Neutron Star: Modeling of Ultraluminous X-Ray Pulsars

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Hiroyuki R. [Center for Computational Astrophysics, National Astronomical Observatory of Japan, National Institutes of Natural Sciences, Mitaka, Tokyo 181-8588 (Japan); Ohsuga, Ken, E-mail: takahashi@cfca.jp, E-mail: ken.ohsuga@nao.ac.jp [Division of Theoretical Astronomy, National Astronomical Observatory of Japan, National Institutes of Natural Sciences, Mitaka, Tokyo 181-8588 (Japan)

    2017-08-10

    By performing 2.5-dimensional general relativistic radiation magnetohydrodynamic simulations, we demonstrate supercritical accretion onto a non-rotating, magnetized neutron star, where the magnetic field strength of dipole fields is 10{sup 10} G on the star surface. We found the supercritical accretion flow consists of two parts: the accretion columns and the truncated accretion disk. The supercritical accretion disk, which appears far from the neutron star, is truncated at around ≃3 R {sub *} ( R {sub *} = 10{sup 6} cm is the neutron star radius), where the magnetic pressure via the dipole magnetic fields balances with the radiation pressure of the disks. The angular momentum of the disk around the truncation radius is effectively transported inward through magnetic torque by dipole fields, inducing the spin up of a neutron star. The evaluated spin-up rate, ∼−10{sup −11} s s{sup −1}, is consistent with the recent observations of the ultraluminous X-ray pulsars. Within the truncation radius, the gas falls onto a neutron star along the dipole fields, which results in a formation of accretion columns onto the northern and southern hemispheres. The net accretion rate and the luminosity of the column are ≃66 L {sub Edd}/ c {sup 2} and ≲10 L {sub Edd}, where L {sub Edd} is the Eddington luminosity and c is the light speed. Our simulations support a hypothesis whereby the ultraluminous X-ray pulsars are powered by the supercritical accretion onto the magnetized neutron stars.

  15. On the radiation beaming of bright X-ray pulsars and constraints on neutron star mass-radius relation

    Science.gov (United States)

    Mushtukov, Alexander A.; Verhagen, Patrick A.; Tsygankov, Sergey S.; van der Klis, Michiel; Lutovinov, Alexander A.; Larchenkova, Tatiana I.

    2018-03-01

    The luminosity of accreting magnetized neutron stars can largely exceed the Eddington value due to appearance of accretion columns. The height of the columns can be comparable to the neutron star radius. The columns produce the X-rays detected by the observer directly and illuminate the stellar surface, which reprocesses the X-rays and causes additional component of the observed flux. The geometry of the column and the illuminated part of the surface determine the radiation beaming. Curved space-time affects the angular flux distribution. We construct a simple model of the beam patterns formed by direct and reflected flux from the column. We take into account the possibility of appearance of accretion columns, whose height is comparable to the neutron star radius. We argue that depending on the compactness of the star, the flux from the column can be either strongly amplified due to gravitational lensing, or significantly reduced due to column eclipse by the star. The eclipses of high accretion columns result in specific features in pulse profiles. Their detection can put constraints on the neutron star radius. We speculate that column eclipses are observed in X-ray pulsar V 0332+53, leading us to the conclusion of large neutron star radius in this system (˜15 km if M ˜ 1.4 M⊙). We point out that the beam pattern can be strongly affected by scattering in the accretion channel at high luminosity, which has to be taken into account in the models reproducing the pulse profiles.

  16. Sigma observation of the pulsar OAO 1657 - 415: Precise localization at hard X-ray energy and discovery of spin-down

    International Nuclear Information System (INIS)

    Mereghetti, S.; Mandrou, P.; Natalucci, L.; Ballet, J.; Lambert, A.

    1991-01-01

    The region of sky containing the 38 s X-ray pulsar OAO 1657 - 415 has been observed on March 1990 with Sigma, an imaging gamma-ray telescope exploiting the coded mask technique. This observation has yielded an accurate (about arcminute-scale) localization for OAO 1657 - 415 at hard X-ray energy, confirming its association with a previously suggested soft X-ray candidate. A timing analysis of the 40-120 keV data has revealed for the first time a spin-down episode in OAO 1657 - 415, implying that an important change in the accretion torque experienced by this X-ray pulsar must have recently occurred. 18 refs

  17. High-energy X-rays from J174545.5-285829, the cannonball: a candidate pulsar wind nebula associated with SGR a east

    DEFF Research Database (Denmark)

    Nynka, Melania; Hailey, Charles J.; Mori, Kaya

    2013-01-01

    pulsar wind nebula (PWN) located ~ 2' north-east from Sgr A*, just outside the radio shell of the supernova remnant Sagittarius A (Sgr A) East. Its non-thermal X-ray spectrum, measured up to 30 keV, is well characterized by a Γ ~ 1.6 power law, typical of a PWN, and has an X-ray luminosity of L (3-30 ke...

  18. The Radio and X-ray Mode-Switching Pulsar PSR B0943+10

    Indian Academy of Sciences (India)

    Observations obtained in the last years challenged the widespread notion that rotation-powered neutron stars are steady X-ray emitters. Besides a few allegedly rotation-powered neutron stars that showed 'magnetar-like' variability, a particularly interesting case is that of PSR B0943+10. Recent observations have shown ...

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

    International Nuclear Information System (INIS)

    Mori, Kaya; Gotthelf, Eric V.; Halpern, Jules P.; Beloborodov, Andrei M.; Hailey, Charles J.; Dufour, Francois; Kaspi, Victoria M.; An, Hongjun; Bachetti, Matteo; Boggs, Steven E.; Craig, William W.; Christensen, Finn E.; Harrison, Fiona A.; Kouveliotou, Chryssa; Pivovaroff, Michael J.; Stern, Daniel; Zhang, William W.

    2014-01-01

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

  20. X-ray spectra from magnetar candidates - III. Fitting SGR/AXP soft X-ray emission with non-relativistic Monte Carlo models

    NARCIS (Netherlands)

    Zane, S.; Rea, N.; Turolla, R.; Nobili, L.

    2009-01-01

    Within the magnetar scenario, the ‘twisted magnetosphere’ model appears very promising in explaining the persistent X-ray emission from soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs). In the first two papers of the series, we have presented a 3D Monte Carlo code for solving radiation

  1. HIGH SPATIAL RESOLUTION X-RAY SPECTROSCOPY OF THE IC 443 PULSAR WIND NEBULA AND ENVIRONS

    Energy Technology Data Exchange (ETDEWEB)

    Swartz, Douglas A.; Zavlin, Vyacheslav E. [USRA, Astrophysics Office, NASA Marshall Space Flight Center, ZP12, Huntsville, AL 35812 (United States); Pavlov, George G. [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Clarke, Tracy [Remote Sensing Division, Code 7213, Naval Research Laboratory, 4555 Overlook Avenue, SW, Washington, DC (United States); Castelletti, Gabriela [Instituto de Astronomía y Física del Espacio (IAFE, CONICET-UBA), CC67, Suc. 28, 1428, Buenos Aires (Argentina); Bucciantini, Niccolò [INAF—Osservatorio Astrofisico di Arcetri, L. go E. Fermi 5, I-50125 Firenze (Italy); Karovska, Margarita [Smithsonian Astrophysical Observatory, MS 4, 60 Garden Street, Cambridge, MA 02138 (United States); Horst, Alexander J. van der [Department of Physics, The George Washington University, 725 21 Street NW, Washington, DC 20052 (United States); Yukita, Mihoko [The Johns Hopkins University, Homewood Campus, Baltimore, MD 21218 (United States); Weisskopf, Martin C. [Astrophysics Office, NASA Marshall Space Flight Center, ZP12, Huntsville, AL 35812 (United States)

    2015-07-20

    Deep Chandra ACIS observations of the region around the putative pulsar, CXOU J061705.3+222127, in the supernova remnant (SNR) IC 443 reveal an ∼5″ radius ring-like structure surrounding the pulsar and a jet-like feature oriented roughly north–south across the ring and through the pulsar's location at 06{sup h}17{sup m}5.{sup s}200 + 22°21′27.″52 (J2000.0 coordinates). The observations further confirm that (1) the spectrum and flux of the central object are consistent with a rotation-powered pulsar, (2) the non-thermal spectrum and morphology of the surrounding nebula are consistent with a pulsar wind, and (3) the spectrum at greater distances is consistent with thermal emission from the SNR. The cometary shape of the nebula, suggesting motion toward the southwest, appears to be subsonic: There is no evidence either spectrally or morphologically for a bow shock or contact discontinuity; the nearly circular ring is not distorted by motion through the ambient medium; and the shape near the apex of the nebula is narrow. Comparing this observation with previous observations of the same target, we set a 99% confidence upper limit to the proper motion of CXOU J061705.3+222127 to be less than 44 mas yr{sup −1} (310 km s{sup −1} for a distance of 1.5 kpc), with the best-fit (but not statistically significant) projected direction toward the west.

  2. The donor star of the X-ray pulsar X1908+075

    Science.gov (United States)

    Martínez-Núñez, S.; Sander, A.; Gímenez-García, A.; Gónzalez-Galán, A.; Torrejón, J. M.; Gónzalez-Fernández, C.; Hamann, W.-R.

    2015-06-01

    High-mass X-ray binaries consist of a massive donor star and a compact object. While several of those systems have been well studied in X-rays, little is known for most of the donor stars as they are often heavily obscured in the optical and ultraviolet regime. There is an opportunity to observe them at infrared wavelengths, however. The goal of this study is to obtain the stellar and wind parameters of the donor star in the X1908+075 high-mass X-ray binary system with a stellar atmosphere model to check whether previous studies from X-ray observations and spectral morphology lead to a sufficient description of the donor star. We obtained H- and K-band spectra of X1908+075 and analysed them with the Potsdam Wolf-Rayet (PoWR) model atmosphere code. For the first time, we calculated a stellar atmosphere model for the donor star, whose main parameters are: Mspec = 15 ± 6 M⊙, T∗ = 23-3+6 kK, log geff = 3.0 ± 0.2 and log L/L⊙ = 4.81 ± 0.25. The obtained parameters point towards an early B-type (B0-B3) star, probably in a supergiant phase. Moreover we determined a more accurate distance to the system of 4.85 ± 0.50 kpc than the previously reported value. Based on observations made with the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.Appendix A is available in electronic form at http://www.aanda.org

  3. Understanding the spectral and timing behaviour of a newly discovered transient X-ray pulsar Swift J0243.6+6124

    DEFF Research Database (Denmark)

    Jaisawal, Gaurava K.; Naik, Sachindra; Chenevez, Jérôme

    2018-01-01

    We present the results obtained from timing and spectral studies of the newly discovered accreting X-ray binary pulsar Swift J0243.6+6124 using Nuclear Spectroscopy Telescope Array observation in 2017 October at a flux level of ~280 mCrab. Pulsations at 9.854 23(5) s were detected in the X...

  4. EXTraS discovery of a 1.2-s X-ray pulsar in M31

    Science.gov (United States)

    Esposito, P.; Israel, G.; Belfiore, A.; Novara, G.; Sidoli, L.; Rodriguez Castillo, G.; De Luca, A.; Tiengo, A.; Haberl, F.; Salvaterra, R.

    2017-10-01

    A systematic search for periodic signals in the XMM-Newton's EPIC archive carried out within the EXTraS project resulted in the discovery of a 1.2-s flux modulation in 3XMM J004301.4+413017. It is the first accreting neutron star in M31 for which the spin period has been detected. Besides this distinction, 3XMM J0043 proved to be an interesting system. Doppler shifts of the spin modulation revealed an orbital motion with period of 1.27 d and the analysis of optical data shows that, while the source is likely associated to a globular cluster, a counterpart with V ˜ 22 outside the cluster cannot be excluded. The emission of the pulsar appears rather hard (most data are described by a power law with photon index <1) and, assuming the distance to M31, the 0.3-10 keV luminosity was variable, from ˜3×10^{37} to 2×10^{38} erg/s. Based on this, we discuss two main possible scenarios for 3X J0043: a peculiar low-mass X-ray binary, perhaps similar to 4U 1822-37 or 4U 1626-67, or an intermediate-mass X-ray binary akin Her X-1.

  5. Anomalous scattering and isomorphous replacement in X-ray diffuse scattering holography

    Czech Academy of Sciences Publication Activity Database

    Kopecký, Miloš; Kub, Jiří; Busetto, E.; Lausi, A.; Fábry, Jan; Šourek, Zbyněk

    2007-01-01

    Roč. 204, č. 8 (2007), s. 2572-2577 ISSN 1862-6300 R&D Projects: GA AV ČR IAA100100529; GA MŠk LA 287 Institutional research plan: CEZ:AV0Z10100523; CEZ:AV0Z10100520 Keywords : x-ray difuse scattering * x-ray holography Subject RIV: BM - Solid Matter Physics ; Magnetism

  6. High-Energy X-rays from J174545.5-285829, the Cannonball: a Candidate Pulsar Wind Nebula Associated with Sgr a East

    Science.gov (United States)

    Nynka, Melania; Hailey, Charles J.; Mori, Kaya; Baganoff, Frederick K.; Bauer, Franz E.; Boggs, Steven E.; Craig, William W.; Christensen, Finn E.; Gotthelf, Eric V.; Harrison, Fiona A.; hide

    2013-01-01

    We report the unambiguous detection of non-thermal X-ray emission up to 30 keV from the Cannonball, a few arcsecond long diffuse X-ray feature near the Galactic Center, using the NuSTAR X-ray observatory. The Cannonball is a high-velocity (v(proj) approximately 500 km s(exp -1)) pulsar candidate with a cometary pulsar wind nebula (PWN) located approximately 2' north-east from Sgr A*, just outside the radio shell of the supernova remnant Sagittarius A (Sgr A) East. Its non-thermal X-ray spectrum, measured up to 30 keV, is well characterized by a Gamma is approximately 1.6 power law, typical of a PWN, and has an X-ray luminosity of L(3-30 keV) = 1.3 × 10(exp 34) erg s(exp -1). The spectral and spatial results derived from X-ray and radio data strongly suggest a runaway neutron star born in the Sgr A East supernova event. We do not find any pulsed signal from the Cannonball. The NuSTAR observations allow us to deduce the PWN magnetic field and show that it is consistent with the lower limit obtained from radio observations.

  7. X-Ray Observations of XSS J12270-4859 in a New Low State: A Transformation to a Disk-free Rotation-powered Pulsar Binary

    Science.gov (United States)

    Bogdanov, Slavko; Patruno, Alessandro; Archibald, Anne M.; Bassa, Cees; Hessels, Jason W. T.; Janssen, Gemma H.; Stappers, Ben W.

    2014-07-01

    We present XMM-Newton and Chandra observations of the low-mass X-ray binary XSS J12270-4859, which experienced a dramatic decline in optical/X-ray brightness at the end of 2012, indicative of the disappearance of its accretion disk. In this new state, the system exhibits previously absent orbital-phase-dependent, large-amplitude X-ray modulations with a decline in flux at superior conjunction. The X-ray emission remains predominantly non-thermal but with an order of magnitude lower mean luminosity and significantly harder spectrum relative to the previous high flux state. This phenomenology is identical to the behavior of the radio millisecond pulsar (MSP) binary PSR J1023+0038 in the absence of an accretion disk, where the X-ray emission is produced in an intra-binary shock driven by the pulsar wind. This further demonstrates that XSS J12270-4859 no longer has an accretion disk and has transformed to a full-fledged eclipsing "redback" system that hosts an active rotation-powered MSP. There is no evidence for diffuse X-ray emission associated with the binary that may arise due to outflows or a wind nebula. An extended source situated 1.'5 from XSS J12270-4859 is unlikely to be associated, and is probably a previously uncataloged galaxy cluster.

  8. X-ray observations of XSS J12270-4859 in a new low state: A transformation to a disk-free rotation-powered pulsar binary

    Energy Technology Data Exchange (ETDEWEB)

    Bogdanov, Slavko [Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Patruno, Alessandro [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA, Leiden (Netherlands); Archibald, Anne M.; Bassa, Cees; Hessels, Jason W. T.; Janssen, Gemma H. [ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Stappers, Ben W., E-mail: slavko@astro.columbia.edu [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom)

    2014-07-01

    We present XMM-Newton and Chandra observations of the low-mass X-ray binary XSS J12270-4859, which experienced a dramatic decline in optical/X-ray brightness at the end of 2012, indicative of the disappearance of its accretion disk. In this new state, the system exhibits previously absent orbital-phase-dependent, large-amplitude X-ray modulations with a decline in flux at superior conjunction. The X-ray emission remains predominantly non-thermal but with an order of magnitude lower mean luminosity and significantly harder spectrum relative to the previous high flux state. This phenomenology is identical to the behavior of the radio millisecond pulsar (MSP) binary PSR J1023+0038 in the absence of an accretion disk, where the X-ray emission is produced in an intra-binary shock driven by the pulsar wind. This further demonstrates that XSS J12270-4859 no longer has an accretion disk and has transformed to a full-fledged eclipsing 'redback' system that hosts an active rotation-powered MSP. There is no evidence for diffuse X-ray emission associated with the binary that may arise due to outflows or a wind nebula. An extended source situated 1.'5 from XSS J12270-4859 is unlikely to be associated, and is probably a previously uncataloged galaxy cluster.

  9. Dynamical and Radiative Properties of X-Ray Pulsar Accretion Columns: Effects of Gas and Radiation Pressure

    Science.gov (United States)

    West, Brent Frederick

    Previous research to investigate the dynamics of luminous X-ray pulsars and the observed spectra has largely been confined to the single-fluid model in which the higher luminosity permits the accreting flow to be regarded as a radiation-dominated ideal fluid. In this regime, the inflowing ionized gas held no special significance when investigating the dynamics of accretion column formation and the associated radiation-dominated standing shock through which the fluid must pass. This PhD research examines the dynamical importance of gas pressure in both low-luminosity and high-luminosity X-ray pulsars in which the pressure of the ionized gas may play a significant role in column formation and its associated dynamics. The "two-fluid" model is implemented by coupling radiation and gas as interacting fluids. The fluids pass through a radiation sonic point located in a shock wave where the radiation sound speed equals the bulk fluid speed. The precise location of the sonic point largely depends upon the details of the upstream boundary conditions for the incident radiation and gas sound speeds. The parameter space for the incident sound speeds is mapped and the associated temperature, pressure, and density distributions are calculated as functions of the altitude in the column. The complete dynamical problem is fully modeled by defining five fundamental free parameters, namely: (1) the polar cap size, (2) the altitude at the top of the accretion column, (3) the incident radiation Mach number, (4) the parallel scattering cross-section, and (5) the angle-averaged scattering cross-section. All of the other model parameters are derived from these fundamental free parameters. The resulting X-ray spectral formation is investigated through numerical computation based on the transport equation developed by Becker & Wolff (2007) which accounts for the bulk and thermal Comptonization inside the accreting gas. The Becker & Wolff (2007) model generally gives good agreement with the

  10. Chandra studies of the globular cluster 47 Tucanae: A deeper X-ray source catalogue, five new X-ray counterparts to millisecond radio pulsars, and new constraints to r-mode instability window

    Science.gov (United States)

    Bhattacharya, Souradeep; Heinke, Craig O.; Chugunov, Andrey I.; Freire, Paulo C. C.; Ridolfi, Alessandro; Bogdanov, Slavko

    2017-12-01

    We combined Chandra ACIS observations of the globular cluster 47 Tucanae (47 Tuc) from 2000, 2002 and 2014-2015 to create a deeper X-ray source list, and study some of the faint radio millisecond pulsars (MSPs) present in this cluster. We have detected 370 X-ray sources within the half-mass radius (2.79 arcsec) of the cluster, 81 of which are newly identified, by including new data and using improved source detection techniques. The majority of the newly identified sources are in the crowded core region, indicating cluster membership. We associate five of the new X-ray sources with chromospherically active BY Dra or W UMa variables identified by Albrow et al. We present alternative positions derived from two methods, centroiding and image reconstruction, for faint, crowded sources. We are able to extract X-ray spectra of the recently discovered MSPs 47 Tuc aa, 47 Tuc ab, the newly timed MSP 47 Tuc Z, and the newly resolved MSPs 47 Tuc S and 47 Tuc F. Generally, they are well fitted by blackbody or neutron star atmosphere models, with temperatures, luminosities and emitting radii similar to those of other known MSPs in 47 Tuc, though 47 Tuc aa and 47 Tuc ab reach lower X-ray luminosities. We limit X-ray emission from the full surface of the rapidly spinning (542 Hz) MSP 47 Tuc aa, and use this limit to put an upper bound for amplitude of r-mode oscillations in this pulsar as α < 2.5 × 10-9 and constrain the shape of the r-mode instability window.

  11. Modelling of cation displacements in SrTiO.sub.3./sub. by means of multi-energy anomalous X-ray diffuse scattering

    Czech Academy of Sciences Publication Activity Database

    Kopecký, Miloš; Fábry, Jan; Kub, Jiří

    2016-01-01

    Roč. 49, Jun (2016), 1016-1020 ISSN 1600-5767 R&D Projects: GA ČR GA15-04121S Institutional support: RVO:68378271 Keywords : X-ray diffuse scattering * atomic displacements * anomalous X-ray scattering * SrTiO 3 Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.495, year: 2016

  12. Suzaku X-Ray Study of an Anomalous Source XSS J12270-4859

    Science.gov (United States)

    Saitou, Kei; Tsujimoto, Masahiro; Ebisawa, Ken; Ishida, Manabu

    2009-08-01

    We report on the results of a Suzaku X-ray observation of XSSJ12270-4859, one of the hard X-ray sources in the INTEGRAL catalogue. This object has been classified as an intermediate polar (IP) by its optical spectra, and a putative X-ray period of ˜860s. With a 30ks exposure by Suzaku, we obtained a well-exposed spectrum in the 0.2--70keV band. We conclude against a previous IP classification based on a lack of Fe Kα emission features in the spectrum and a failure to confirm the previously reported X-ray period. Instead, the X-ray light curve is filled with exotic phenomena, including repetitive flares lasting for ˜100s, occasional dips with no apparent periodicities, spectral hardening after some flares, and bimodal changes pivoting between quiet and active phases. The rapid flux changes, the dips, and the power-law spectrum point toward an interpretation that this is a low-mass X-ray binary. Some temporal characteristics are similar to those in the Rapid Burster and GRO J1744-28, making XSS J12270-4859 a very rare object.

  13. ORDINARY X-RAYS FROM THREE EXTRAORDINARY MILLISECOND PULSARS: XMM-NEWTON OBSERVATIONS OF PSRs J0337+1715, J0636+5129, AND J0645+5158

    Energy Technology Data Exchange (ETDEWEB)

    Spiewak, Renée; Kaplan, David L. [Department of Physics, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, WI 53201 (United States); Archibald, Anne; Hessels, Jason [ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Gentile, Peter; Lorimer, Duncan; McLaughlin, Maura [Department of Physics, West Virginia University, 210E Hodges Hall, Morgantown, WV 26506 (United States); Lynch, Ryan; Ransom, Scott [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22901 (United States); Stairs, Ingrid [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Stovall, Kevin [Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131 (United States)

    2016-05-01

    We present the first X-ray observations of three recently discovered millisecond pulsars (MSPs) with interesting characteristics: PSR J0337+1715, PSR J0636+5129, and PSR J0645+5158. PSR J0337+1715 is a fast-spinning, bright, and so-far unique MSP in a hierarchical triple system with two white dwarf companions. PSR J0636+5129 is an MSP in a very tight 96-minute orbit with a low-mass, 8 M {sub J} companion. PSR J0645+5158 is a nearby, isolated MSP with a very small duty cycle (1%–2%), which has led to its inclusion in high-precision pulsar timing programs. Using data from XMM-Newton , we have analyzed X-ray spectroscopy for these three objects, as well as optical/ultraviolet photometry for PSR J0337+1715. The X-ray data for each are largely consistent with expectations for most MSPs with regards to the ratios of thermal and non-thermal emission. We discuss the implications of these data on the pulsar population, and prospects for future observations of these pulsars.

  14. ORDINARY X-RAYS FROM THREE EXTRAORDINARY MILLISECOND PULSARS: XMM-NEWTON OBSERVATIONS OF PSRs J0337+1715, J0636+5129, AND J0645+5158

    International Nuclear Information System (INIS)

    Spiewak, Renée; Kaplan, David L.; Archibald, Anne; Hessels, Jason; Gentile, Peter; Lorimer, Duncan; McLaughlin, Maura; Lynch, Ryan; Ransom, Scott; Stairs, Ingrid; Stovall, Kevin

    2016-01-01

    We present the first X-ray observations of three recently discovered millisecond pulsars (MSPs) with interesting characteristics: PSR J0337+1715, PSR J0636+5129, and PSR J0645+5158. PSR J0337+1715 is a fast-spinning, bright, and so-far unique MSP in a hierarchical triple system with two white dwarf companions. PSR J0636+5129 is an MSP in a very tight 96-minute orbit with a low-mass, 8 M J companion. PSR J0645+5158 is a nearby, isolated MSP with a very small duty cycle (1%–2%), which has led to its inclusion in high-precision pulsar timing programs. Using data from XMM-Newton , we have analyzed X-ray spectroscopy for these three objects, as well as optical/ultraviolet photometry for PSR J0337+1715. The X-ray data for each are largely consistent with expectations for most MSPs with regards to the ratios of thermal and non-thermal emission. We discuss the implications of these data on the pulsar population, and prospects for future observations of these pulsars.

  15. A Search for Millisecond-pulsar Radio Emission from the Faint Quiescent Soft X-Ray Transient 1H 1905+000

    Energy Technology Data Exchange (ETDEWEB)

    Mikhailov, K.; Van Leeuwen, J. [Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, P.O. Box 94249, 1090 GE Amsterdam (Netherlands); Jonker, P. G., E-mail: K.Mikhailov@uva.nl [SRON, the Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA, Utrecht (Netherlands)

    2017-05-01

    Transitional millisecond pulsars (tMSPs) switch between an accretion-powered state without radio pulsations and a rotation-powered state with radio pulsations. In the former state, tMSPs are X-ray bright, while in the latter state, they are X-ray dim. Soft X-ray transients (SXTs) undergo similar switches in X-ray, between “high” states with bright X-ray outbursts and “low” states of quiescence. The upper limit on the quiescent X-ray luminosity of SXT 1H 1905+000 suggests that its luminosity might be similar to that of the known tMSPs. A detection of radio pulsations would link SXTs more strongly with tMSPs; and thus, e.g., put stricter constraints on tMSP transitional timescales through the connection with the well-known SXT periods of quiescence. A nondetection allows us, based on the telescope sensitivity, to estimate how likely these sources are to pulsate in radio. Over a 10-year span, 2006–2015, we carried out targeted radio observations at 400/800 MHz with Arecibo, and searched for radio pulsations from the quiescent SXT 1H 1905+000. None of the observations have revealed radio pulsations from the targeted SXT. For a 1 ms pulsar, our flux density upper limit is 10.3 μ Jy. At an assumed distance of 10 kpc this translates to a pseudo-luminosity upper limit of 1.0 mJy kpc{sup 2}, which makes our search complete to ∼85% of the known MSP population. Given the high sensitivity, and the generally large beaming fraction of millisecond pulsars, we conclude that SXT 1H 1905+000 is unlikely to emit in radio as a tMSP.

  16. Low mass X-ray binaries in the Inner Galaxy: implications for millisecond pulsars and the GeV excess

    Energy Technology Data Exchange (ETDEWEB)

    Haggard, Daryl; Heinke, Craig; Hooper, Dan; Linden, Tim

    2017-05-01

    If millisecond pulsars (MSPs) are responsible for the excess gamma-ray emission observed from the region surrounding the Galactic Center, the same region should also contain a large population of low-mass X-ray binaries (LMXBs). In this study, we compile and utilize a sizable catalog of LMXBs observed in the the Milky Way's globular cluster system and in the Inner Galaxy, as well as the gamma-ray emission observed from globular clusters, to estimate the flux of gamma rays predicted from MSPs in the Inner Galaxy. From this comparison, we conclude that only up to $\\sim$4-23% of the observed gamma-ray excess is likely to originate from MSPs. This result is consistent with, and more robust than, previous estimates which utilized smaller samples of both globular clusters and LMXBs. If MSPs had been responsible for the entirety of the observed excess, INTEGRAL should have detected $\\sim$$10^3$ LMXBs from within a $10^{\\circ}$ radius around the Galactic Center, whereas only 42 LMXBs (and 46 additional LMXB candidates) have been observed.

  17. High-energy X-ray imaging of the pulsar wind nebula MSH 15-52: constraints on particle acceleration and transport

    DEFF Research Database (Denmark)

    An, Hongjun; Madsen, Kristin K.; Reynolds, Stephen P.

    2014-01-01

    We present the first images of the pulsar wind nebula (PWN) MSH 15−52 in the hard X-ray band (8 keV), as measured with the Nuclear Spectroscopic Telescope Array (NuSTAR). Overall, the morphology of the PWN as measured by NuSTAR in the 3–7 keV band is similar to that seen in Chandra high-resolutio......We present the first images of the pulsar wind nebula (PWN) MSH 15−52 in the hard X-ray band (8 keV), as measured with the Nuclear Spectroscopic Telescope Array (NuSTAR). Overall, the morphology of the PWN as measured by NuSTAR in the 3–7 keV band is similar to that seen in Chandra high...

  18. Discovery of a 1.69 ms radio pulsar associated with the X-ray binary XSS J12270-4859

    Science.gov (United States)

    Ray, Paul S.; Roy, Jayanta; Bhattacharyya, Bhaswati; Stappers, Benjamin; Chengalur, Jayaram N.; Deneva, Julia S.; Camilo, Fernando M.

    2015-01-01

    XSS J12270-4859 is an X-ray binary associated with the Fermi LAT gamma-ray source 1FGL J1227.9-4852 (Hill et al. 2011). In 2012 December, the source underwent a transition where the X-ray and optical luminosity dropped suddenly and spectral signatures of an accretion disk disappeared (Bassa et al. 2014). We report the discovery of a 1.69 millisecond pulsar using the Giant Metrewave Radio Telescope at 607 MHz associated with this source, confirming that system is now an active radio millisecond pulsar. We report on radio timing observations of the source with the GMRT and Parkes Telescope that allow precise determination of the orbital parameters of the system. In addition, using simultaneous radio imaging and timing observations with the GMRT, we are able to study the eclipse behavior.

  19. Anomalous grazing incidence small-angle x-ray scattering studies of Pt nanoparticles formed by cluster deposition

    International Nuclear Information System (INIS)

    Lee, B.; Seifert, S.; Riley, S.J.; Tikhonov, G.Y.; Tomczyk, N.A.; Vajda, S.; Winans, R.E.

    2005-01-01

    The size evolution of platinum nanoparticles formed on a SiO2/Si(111) substrate as a function of the level of surface coverage with deposited clusters has been investigated. The anisotropic shapes of sub-nanometer-size nanoparticles are changed to isotropic on the amorphous substrate as their sizes increased. Using anomalous grazing incidence small-angle x-ray scattering (AGISAXS), the scattering from nanoparticles on the surface of a substrate is well separated from that of surface roughness and fluorescence. We show that AGISAXS is a very effective method to subtract the background and can provide unbiased information about particle sizes of less than 1 nm.

  20. Observation of parametric X-ray radiation in an anomalous diffraction region

    Energy Technology Data Exchange (ETDEWEB)

    Alexeyev, V.I., E-mail: vial@x4u.lebedev.ru [P.N. Lebedev Physical Institute RAS, 53 Leninskiy prospect, Moscow (Russian Federation); Belgorod National Research University, 85 Pobedy st., Belgorod (Russian Federation); Eliseyev, A.N., E-mail: elisseev@pluton.lpi.troitsk.ru [P.N. Lebedev Physical Institute RAS, 53 Leninskiy prospect, Moscow (Russian Federation); Belgorod National Research University, 85 Pobedy st., Belgorod (Russian Federation); Irribarra, E., E-mail: esteban.irribarra@epn.edu.ec [Escuela Politécnica Nacional, Ladrón de Guevara E11-253, Quito (Ecuador); Kishin, I.A., E-mail: ivan.kishin@mail.ru [P.N. Lebedev Physical Institute RAS, 53 Leninskiy prospect, Moscow (Russian Federation); Belgorod National Research University, 85 Pobedy st., Belgorod (Russian Federation); Kubankin, A.S., E-mail: kubankin@bsu.edu.ru [P.N. Lebedev Physical Institute RAS, 53 Leninskiy prospect, Moscow (Russian Federation); Belgorod National Research University, 85 Pobedy st., Belgorod (Russian Federation); Nazhmudinov, R.M., E-mail: fizeg@bk.ru [P.N. Lebedev Physical Institute RAS, 53 Leninskiy prospect, Moscow (Russian Federation); Belgorod National Research University, 85 Pobedy st., Belgorod (Russian Federation)

    2016-08-19

    A new possibility to expand the energy region of diffraction processes based on the interaction of relativistic charged particles with crystalline structures is presented. Diffracted photons related to parametric X-ray radiation produced by relativistic electrons are detected below the low energy threshold for the X-ray diffraction mechanism in crystalline structures for the first time. The measurements were performed during the interaction of 7 MeV electrons with a textured polycrystalline tungsten foil and a highly oriented pyrolytic graphite crystal. The experiment results are in good agreement with a developed model based on the PXR kinematical theory. The developed experimental approach can be applied to separate the contributions of real and virtual photons to the total diffracted radiation generated during the interaction of relativistic charged particles with crystalline targets. - Highlights: • Parametric X-ray radiation below the low energy threshold for diffraction of free X-rays. • Experimental separation of the contributions from different radiation mechanisms. • PXR from relativistic electrons in mosaic crystals and textured polycrystlas.

  1. XSS J12270-4859: A Transformation from an X-ray Binary to a Rotation-Powered Millisecond Pulsar System

    Science.gov (United States)

    Bogdanov, Slavko; Bassa, Cees; Archibald, Anne M; Patruno, Alessandro; Hessels, Jason; Janssen, Gemma H; Stappers, Benjamin; Tendulkar, Shriharsh P.

    2014-08-01

    XSS J12270-4859 has been previously suggested to be a low-mass X-ray binary, and until recently the only such system to be seen at MeV-GeV energies. We present radio, optical and X-ray observations that demonstrate that XSS J12270-4859 has undergone a sudden decline in optical and X-ray brightness and no longer shows evidence for an accretion disk. Along with the recent detection of radio pulsations, these findings indicate that XSS J12270-4859 transformed to a full-fledged eclipsing "redback" system between 2012 November 14 and December 21 and presently hosts an active rotation-powered millisecond pulsar.

  2. Methods in the determination of partial structure factors of disordered matter by neutron and anomalous X-ray diffraction

    International Nuclear Information System (INIS)

    Suck, J.B.; Chieux, P.; Raoux, D.; Riekel, C.

    1993-01-01

    A general introduction into all possible binary correlations (nuclear-nuclear correlations, mass-mass, charge-charge, nuclear-magnetic, nuclear-electronic, etc.), is followed by methods used in connection with neutron diffraction (and also to neutron inelastic scattering) like isotopic substitution, first and second order difference methods, isomorphic substitution and anomalous neutron diffraction. Then the X-ray anomalous scattering methods used specifically in connection with synchrotron radiation are presented. For both radiation methods and results for wide angle and small angle diffraction are included. Applications of both methods to special systems and problems inherent in these combinations are discussed. Methods and results obtained by computer simulations, Reverse Monte Carlo calculations and a new regularization method used in context with an optimization of compatible data obtained with different methods on the same system, are presented. A translation kit is proposed for semantic purposes between the two domains

  3. The first multi-wavelength campaign of AXP 4U 0142+61 from radio to hard X-rays

    NARCIS (Netherlands)

    den Hartog, P.R.; Kuiper, L.; Hermsen, W.; Rea, N.; Durant, M.; Stappers, B.; Kaspi, V.M.; Dib, R.

    2007-01-01

    For the first time a quasi-simultaneous multi-wavelength campaign has been performed on an Anomalous X-ray Pulsar from the radio to the hard X-ray band. 4U 0142+61 was an INTEGRAL target for 1 Ms in July 2005. During these observations it was also observed in the X-ray band with Swift and RXTE, in

  4. INTEGRAL detection of the multi-peaked emission from the Be/X-ray binary pulsar GRO J1008-57

    DEFF Research Database (Denmark)

    Fiocchi, M.; Sguera, A.; Chenevez, Jérôme

    2014-01-01

    /4 of the outbursts in Be/XRBs (e.g. Kretschmar et al., 2013, arXiv.1302.3434). We will continue to monitor the source activity with INTEGRAL through the GPS programme until December 20th. Light curves and images can be found on the GPS webpages: http://gpsiasf.iasf-roma.inaf.it/......Recent observations from the on-going INTEGRAL Galactic Plane Scanning programme (PI: A. Bazzano) have detected increasing X-ray flux from the Be/X-ray binary pulsar GRO J1008-57, confirming the re-brightening detected by MAXI/GSC (ATel #6819). The source was in the field of view of the IBIS...

  5. X-ray coherent pulsations during a sub-luminous accretion disc state of the transitional millisecond pulsar XSS J12270-4859

    Science.gov (United States)

    Papitto, A.; de Martino, D.; Belloni, T. M.; Burgay, M.; Pellizzoni, A.; Possenti, A.; Torres, D. F.

    2015-04-01

    We present the first detection of X-ray coherent pulsations from the transitional millisecond pulsar XSS J12270-4859, while it was in a sub-luminous accretion disc state characterized by a 0.5-10 keV luminosity of 5 × 1033 erg s-1 (assuming a distance of 1.4 kpc). Pulsations were observed by XMM-Newton at an rms amplitude of (7.7 ± 0.5) per cent with a second harmonic stronger than the fundamental frequency, and were detected when the source is neither flaring nor dipping. The most likely interpretation of this detection is that matter from the accretion disc was channelled by the neutron star magnetosphere and accreted on to its polar caps. According to standard disc accretion theory, for pulsations to be observed the mass inflow rate in the disc was likely larger than the amount of plasma actually reaching the neutron star surface; an outflow launched by the fast rotating magnetosphere then probably took place, in agreement with the observed broad-band spectral energy distribution. We also report about the non-detection of X-ray pulsations during a recent observation performed while the source behaved as a rotationally-powered radio pulsar.

  6. NuSTAR detection of 4s Hard X-ray Lags from the Accreting Pulsar GS 0834-430

    DEFF Research Database (Denmark)

    Bachetti, Matteo; Miyasaka, Hiromasa; Harrison, Fiona

    2014-01-01

    The NuSTAR hard X-ray telescope observed the transient Be/X-ray binary GS 0834􀀀430 during its 2012 outburst. The source is detected between 3 – 79 keV with high statistical significance, and we were able to perform very accurate spectral and timing analysis. The phase-averaged spectrum i...... significantly smaller in phase and restricted to low-energies (Emechanisms that might produce such lags. We find the most likely explanation for this eect to be a complex beam geometry....

  7. UPPER LIMITS ON PULSED RADIO EMISSION FROM THE 6.85 s X-RAY PULSAR XTE J0103-728 IN THE SMALL MAGELLANIC CLOUD

    International Nuclear Information System (INIS)

    Crawford, Fronefield; Devour, Brian M.; Takacs, Brian P.; Lorimer, Duncan R.; Kondratiev, Vladislav I.

    2009-01-01

    X-ray pulsations with a 6.85 s period were recently detected in the Small Magellanic Cloud (SMC) and were subsequently identified as originating from the Be/X-ray binary system XTE J0103-728. The recent localization of the source of the X-ray emission has made a targeted search for radio pulsations from this source possible. The detection of pulsed radio emission from XTE J0103-728 would make it only the second system after PSR B1259-63 that is both a Be/X-ray binary and a radio pulsar. We observed XTE J0103-728 in 2008 February with the Parkes 64 m radio telescope soon after the identification of the source of X-ray pulsations was reported in order to search for corresponding radio pulsations. We used a continuous 6.4 hr observation with a 256 MHz bandwidth centered at 1390 MHz using the center beam of the Parkes multibeam receiver. In the subsequent data analysis, which included a folding search, a Fourier search, a fast-folding algorithm search, and a single pulse search, no pulsed signals were found for trial dispersion measures (DMs) between 0 and 800 pc cm -3 . This DM range easily encompasses the expected values for sources in the SMC. We place an upper limit of ∼45 mJy kpc 2 on the luminosity of periodic radio emission from XTE J0103-728 at the epoch of our observation, and we compare this limit to a range of luminosities measured for PSR B1259-63, the only Be/X-ray binary currently known to emit radio pulses. We also compare our limit to the radio luminosities of neutron stars having similarly long spin periods to XTE J0103-728. Since the radio pulses from PSR B1259-63 are eclipsed and undetectable during the portion of the orbit near periastron, repeated additional radio search observations of XTE J0103-728 may be valuable if it is undergoing similar eclipsing and if such observations are able to sample the orbital phase of this system well.

  8. The Chemically-Specific Structure of an Amorphous Molybdenum Germanium Alloy by Anomalous X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, H. A.

    2002-06-11

    Since its inception in the late 1970s, anomalous x-ray scattering (AXS) has been employed for chemically-specific structure determination in a wide variety of noncrystalline materials. These studies have successfully produced differential distribution functions (DDFs) which provide information about the compositionally-averaged environment of a specific atomic species in the sample. Despite the wide success in obtaining DDFs, there are very few examples of successful extraction of the fully-chemically-specific partial pair distribution functions (PPDFs), the most detailed description of an amorphous sample possible by x-ray scattering. Extracting the PPDFs is notoriously difficult since the matrix equation involved is ill-conditioned and thus extremely sensitive to errors present in the experimental quantities that enter the equation. Instead of addressing this sensitivity by modifying the data through mathematical methods, sources of error have been removed experimentally: A focusing analyzer crystal was combined with a position-sensitive linear detector to experimentally eliminate unwanted inelastic scattering intensity over most of the reciprocal space range probed. This instrumentation has been used in data collection for the extraction of PPDFs from amorphous (a)-MoGe{sub 3}. This composition arises as a phase separation endpoint in the Ge-rich region of the vapor-deposited Mo-Ge amorphous alloy system but is not present at equilibrium. Since the first Ge-rich compound in the Mo-Ge equilibrium system is MoGe{sub 2}, previous workers have speculated that perhaps a unique MoGe{sub 3} compound exists in the amorphous system. Rather than indicating a distinct MoGe{sub 3} compound with definitive local structure, however, the coordination results are more consistent with a densely-packed alloy having a wide range of solid solubility. Significant improvement in the quality and reliability of experimental PPDFs from a-MoGe{sub 3} by AXS has been achieved solely

  9. In situ anomalous small-angle X-ray scattering studies of platinum nanoparticle fuel cell electrocatalyst degradation.

    Science.gov (United States)

    Gilbert, James A; Kariuki, Nancy N; Subbaraman, Ram; Kropf, A Jeremy; Smith, Matt C; Holby, Edward F; Morgan, Dane; Myers, Deborah J

    2012-09-12

    Polymer electrolyte fuel cells (PEFCs) are a promising high-efficiency energy conversion technology, but their cost-effective implementation, especially for automotive power, has been hindered by degradation of the electrochemically active surface area (ECA) of the Pt nanoparticle electrocatalysts. While numerous studies using ex situ post-mortem techniques have provided insight into the effect of operating conditions on ECA loss, the governing mechanisms and underlying processes are not fully understood. Toward the goal of elucidating the electrocatalyst degradation mechanisms, we have followed Pt nanoparticle growth during potential cycling of the electrocatalyst in an aqueous acidic environment using in situ anomalous small-angle X-ray scattering (ASAXS). ASAXS patterns were analyzed to obtain particle size distributions (PSDs) of the Pt nanoparticle electrocatalysts at periodic intervals during the potential cycling. Oxide coverages reached under the applied potential cycling protocols were both calculated and determined experimentally. Changes in the PSD, mean diameter, and geometric surface area identify the mechanism behind Pt nanoparticle coarsening in an aqueous environment. Over the first 80 potential cycles, the dominant Pt surface area loss mechanism when cycling to 1.0-1.1 V was found to be preferential dissolution or loss of the smallest particles with varying extents of reprecipitation of the dissolved species onto existing particles, resulting in particle growth, depending on potential profile. Correlation of ASAXS-determined particle growth with both calculated and voltammetrically determined oxide coverages demonstrates that the oxide coverage is playing a key role in the dissolution process and in the corresponding growth of the mean Pt nanoparticle size and loss of ECA. This understanding potentially reduces the complex changes in PSD and ECA resulting from various voltage profiles to a response dependent on oxide coverage.

  10. INTEGRAL detects a new outburst from the millisecond X-ray pulsar IGR J17511-3057

    DEFF Research Database (Denmark)

    Bozzo, E.; Kuulkers, E.; Bazzano, A.

    2015-01-01

    Crab in the 10-20 keV energy band. All uncertainties on the fluxes are quoted at 1 sigma c.l. The IBIS/ISGRI spectrum (effective exposure time 9.1 ks) could be reasonably well described by using a power-law model with photon index 2.3+/-0.4. The 20-100 keV X-ray flux estimated from the spectral fit is 4.5E-10...

  11. Determination of transition metal ion distribution in cubic spinel Co1.5Fe1.5O4 using anomalous x-ray diffraction

    Directory of Open Access Journals (Sweden)

    M. N. Singh

    2015-08-01

    Full Text Available We report anomalous x-ray diffraction studies on Co ferrite with composition Co1.5Fe1.5O4 to obtain the distribution of transition metal ions in tetrahedral and octahedral sites. We synthesize spinel oxide (Co1.5Fe1.5O4 through co-precipitation and subsequent annealing route. The imaginary part (absorption of the energy dependent anomalous form factor is measured and the real part is calculated theoretically through Kramers–Krönig transformation to analyze anomalous x-ray diffraction peak intensities. Fe and Co K-edge x-ray absorption near edge structure (XANES spectra are used to estimate charge states of transition metals. Our analysis, within experimental errors, suggests 44% of the tetrahedral sites contain Co in +2 oxidation state and the rest 56% sites contain Fe in +2 and +3 oxidation states. Similarly, 47% of the octahedral sites contain Fe in +3 oxidation states, whereas, the rest of the sites contain Co in +2 and +3 oxidation states. While a distinct pre-edge feature in the Fe K-edge XANES is observed, Co pre-edge remains featureless. Implications of these results to magnetism are briefly discussed.

  12. Research on navigation of satellite constellation based on an asynchronous observation model using X-ray pulsar

    Science.gov (United States)

    Guo, Pengbin; Sun, Jian; Hu, Shuling; Xue, Ju

    2018-02-01

    Pulsar navigation is a promising navigation method for high-altitude orbit space tasks or deep space exploration. At present, an important reason for restricting the development of pulsar navigation is that navigation accuracy is not high due to the slow update of the measurements. In order to improve the accuracy of pulsar navigation, an asynchronous observation model which can improve the update rate of the measurements is proposed on the basis of satellite constellation which has a broad space for development because of its visibility and reliability. The simulation results show that the asynchronous observation model improves the positioning accuracy by 31.48% and velocity accuracy by 24.75% than that of the synchronous observation model. With the new Doppler effects compensation method in the asynchronous observation model proposed in this paper, the positioning accuracy is improved by 32.27%, and the velocity accuracy is improved by 34.07% than that of the traditional method. The simulation results show that without considering the clock error will result in a filtering divergence.

  13. High-Energy X-Ray Imaging of the Pulsar Wind Nebula MSH 15-52: Constraints on Particle Acceleration and Transport

    Science.gov (United States)

    An, Hongjun; Madsen, Kristin K.; Reynolds, Stephen P.; Kaspi, Victoria M.; Harrison, Fiona A.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Fryer, Chris L.; Grefenstette, Brian W.; hide

    2014-01-01

    We present the first images of the pulsar wind nebula (PWN) MSH 15-52 in the hard X-ray band (8 keV), as measured with the Nuclear Spectroscopic Telescope Array (NuSTAR). Overall, the morphology of the PWN as measured by NuSTAR in the 3-7 keV band is similar to that seen in Chandra high-resolution imaging. However, the spatial extent decreases with energy, which we attribute to synchrotron energy losses as the particles move away from the shock. The hard-band maps show a relative deficit of counts in the northern region toward the RCW 89 thermal remnant, with significant asymmetry. We find that the integrated PWN spectra measured with NuSTAR and Chandra suggest that there is a spectral break at 6 keV, which may be explained by a break in the synchrotron emitting electron distribution at approximately 200 TeV and/or imperfect cross calibration. We also measure spatially resolved spectra, showing that the spectrum of the PWN softens away from the central pulsar B1509-58, and that there exists a roughly sinusoidal variation of spectral hardness in the azimuthal direction. We discuss the results using particle flow models. We find non-monotonic structure in the variation with distance of spectral hardness within 50 of the pulsar moving in the jet direction, which may imply particle and magnetic-field compression by magnetic hoop stress as previously suggested for this source. We also present two-dimensional maps of spectral parameters and find an interesting shell-like structure in the N(sub H) map. We discuss possible origins of the shell-like structure and their implications.

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

    Energy Technology Data Exchange (ETDEWEB)

    Pintore, F.; Mereghetti, S. [INAF-IASF Milano, via E. Bassini 15, I-20133 Milano (Italy); Zampieri, L. [INAF-Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova (Italy); Stella, L.; Israel, G. L. [INAF—Osservatorio astronomico di Roma, Via Frascati 44, I-00078, Monteporzio Catone (Italy); Wolter, A. [INAF, Osservatorio Astronomico di Brera, via Brera 28, I-20121 Milano (Italy)

    2017-02-10

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

  15. Anomalous lattice behavior of vanadium pentaoxide (V2O5): X-ray diffraction, inelastic neutron scattering and ab initio lattice dynamics.

    Science.gov (United States)

    Singh, Baltej; Gupta, Mayanak Kumar; Mishra, Sanjay Kumar; Mittal, Ranjan; Sastry, P U; Rols, Stephane; Chaplot, Samrath Lal

    2017-07-21

    We present structural and dynamical studies of layered vanadium pentaoxide (V 2 O 5 ). The temperature dependent X-ray diffraction measurements reveal highly anisotropic and anomalous thermal expansion from 12 K to 853 K. The results do not show any evidence of structural phase transition or decomposition of α-V 2 O 5 , contrary to the previous transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) experiments. The inelastic neutron scattering measurements performed up to 673 K corroborate the result of our X-ray diffraction measurements. The analysis of the experimental data is carried out using ab initio lattice dynamics calculations. The important role of van der Waals dispersion and Hubbard interactions in the structure and dynamics is revealed through ab initio calculations. The calculated anisotropic thermal expansion behavior agrees well with temperature dependent X-ray diffraction. The mechanism of anisotropic thermal expansion and anisotropic linear compressibility is discussed in terms of calculated anisotropy in the Grüneisen parameters and elastic coefficients. The calculated Gibbs free energy in various phases of V 2 O 5 is used to understand the high pressure and temperature phase diagram of the compound.

  16. Hard X-ray timing and spectral characteristics of the energetic pulsar PSR J0205+6449 in supernova remnant 3C 58: An RXTE PCA/HEXTE and XMM-Newton view on the 0.5-250 keV band

    NARCIS (Netherlands)

    Kuiper, L.; Hermsen, W.; Urama, J.O.; den Hartog, P.R.; Lyne, A.G.; Stappers, B.W.

    2010-01-01

    Context. PSR J0205+6449 is a young rotation-powered pulsar in SNR 3C 58. It is one of only three young (<10 000 year old) pulsars that have so far been detected in the radio and the classical X-ray bands, as well as at hard X-rays above 20 keV and at high-energy (>100 MeV) gamma-rays. The other two

  17. Synchrotron X-ray diffraction investigation of the anomalous behavior of ice during freezing of aqueous systems.

    Science.gov (United States)

    Varshney, Dushyant B; Elliott, James A; Gatlin, Larry A; Kumar, Satyendra; Suryanarayanan, Raj; Shalaev, Evgenyi Y

    2009-05-07

    Simple aqueous systems, i.e., phosphate-glycine buffers and pure water, were studied at subambient temperatures by X-ray difractometry using a high-intensity synchrotron radiation source at the Advanced Photon Source of Argonne National Laboratory. Complex X-ray diffraction (XRD) patterns, with two or more poorly resolved peaks in place of each of the four diagnostic peaks of hexagonal ice, 100, 002, 101, and 102, referred as "splitting", were observed in the majority of cases. The splitting of up to 0.05 A (d-spacing) was detected for 100, 002, and 101 peaks, whereas 102 peak was less affected. Deformation of the lattice of hexagonal ice, probably due to local stress created on the ice/ice or ice/container interface during water-to-ice transformation, is proposed as a possible mechanism for the observed splitting of XRD peaks. Using molecular modeling, it was estimated that the observed shifts in the peak positions are equivalent to applying a hydrostatic pressure of 2-3 kbars. The splitting can be used to quantify stresses during freezing, which could improve our understanding of the role of water-to-ice transformation on the destabilization of proteins and other biological systems.

  18. X-ray Excitation Triggers Ytterbium Anomalous Emission in CaF 2 :Yb but Not in SrF 2 :Yb

    Energy Technology Data Exchange (ETDEWEB)

    Hughes-Currie, Rosa B.; Ivanovskikh, Konstantin V.; Wells, Jon-Paul R.; Reid, Michael F.; Gordon, Robert A.; Seijo, Luis; Barandiarán, Zoila

    2017-02-27

    Materials that luminesce after excitation with ionizing radiation are extensively applied in physics, medicine, security, and industry. Lanthanide dopants are known to trigger crystal scintillation through their fast d–f emissions; the same is true for other important applications as lasers or phosphors for lighting. However, this ability can be seriously compromised by unwanted anomalous emissions often found with the most common lanthanide activators. We report high-resolution X-ray-excited optical (IR to UV) luminescence spectra of CaF2:Yb and SrF2:Yb samples excited at 8949 eV and 80 K. Ionizing radiation excites the known anomalous emission of ytterbium in the CaF2 host but not in the SrF2 host. Wave function-based ab initio calculations of host-to-dopant electron transfer and Yb2+/Yb3+ intervalence charge transfer explain the difference. The model also explains the lack of anomalous emission in Yb-doped SrF2 excited by VUV radiation.

  19. X-Ray and Optical Study of the Gamma-ray Source 3FGL J0838.8–2829: Identification of a Candidate Millisecond Pulsar Binary and an Asynchronous Polar

    Energy Technology Data Exchange (ETDEWEB)

    Halpern, Jules P.; Bogdanov, Slavko [Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027-6601 (United States); Thorstensen, John R., E-mail: jules@astro.columbia.edu [Department of Physics and Astronomy, 6127 Wilder Laboratory, Dartmouth College, Hanover, NH 03755-3528 (United States)

    2017-04-01

    We observed the field of the Fermi source 3FGL J0838.8−2829 in optical and X-rays, initially motivated by the cataclysmic variable (CV) 1RXS J083842.1−282723 that lies within its error circle. Several X-ray sources first classified as CVs have turned out to be γ -ray emitting millisecond pulsars (MSPs). We find that 1RXS J083842.1−282723 is in fact an unusual CV, a stream-fed asynchronous polar in which accretion switches between magnetic poles (that are ≈120° apart) when the accretion rate is at minimum. High-amplitude X-ray modulation at periods of 94.8 ± 0.4 minutes and 14.7 ± 1.2 hr are seen. The former appears to be the spin period, while the latter is inferred to be one-third of the beat period between the spin and the orbit, implying an orbital period of 98.3 ± 0.5 minutes. We also measure an optical emission-line spectroscopic period of 98.413 ± 0.004 minutes, which is consistent with the orbital period inferred from the X-rays. In any case, this system is unlikely to be the γ -ray source. Instead, we find a fainter variable X-ray and optical source, XMMU J083850.38−282756.8, that is modulated on a timescale of hours in addition to exhibiting occasional sharp flares. It resembles the black widow or redback pulsars that have been discovered as counterparts of Fermi sources, with the optical modulation due to heating of the photosphere of a low-mass companion star by, in this case, an as-yet undetected MSP. We propose XMMU J083850.38−282756.8 as the MSP counterpart of 3FGL J0838.8−2829.

  20. Long-range structure of Cu(InxGa1-x)3Se5: A complementary neutron and anomalous x-ray diffraction study

    Science.gov (United States)

    Lehmann, S.; Marrón, D. fürtes; León, 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 I4¯2m). 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.

  1. Crystal structure determination of solar cell materials: Cu2ZnSnS4 thin films using X-ray anomalous dispersion

    International Nuclear Information System (INIS)

    Nozaki, Hiroshi; Fukano, Tatsuo; Ohta, Shingo; Seno, Yoshiki; Katagiri, Hironori; Jimbo, Kazuo

    2012-01-01

    Highlights: ► Cu 2 ZnSnS 4 thin films as a solar cell material were synthesized. ► The wavelength dependences of the diffraction intensity were measured. ► The crystal structures were clearly identified as kesterite structure for all samples. ► Crystal structure analysis revealed that the atomic compositions were Cu/(Zn + Sn) = 0.97 and Zn/Sn = 1.42 for the sample synthesized using stoichiometric amount of starting materials. - Abstract: The crystal structure of Cu 2 ZnSnS 4 (CZTS) thin films fabricated by vapor-phase sulfurization was determined using X-ray anomalous dispersion. High statistic synchrotron radiation X-ray diffraction data were collected from very small amounts of powder. By analyzing the wavelength dependencies of the diffraction peak intensities, the crystal structure was clearly identified as kesterite. Rietveld analysis revealed that the atomic composition deviated from stoichiometric composition, and the compositions were Cu/(Zn + Sn) = 0.97, and Zn/Sn = 1.42.

  2. X-ray Detection and Processing Models for Spacecraft Navigation and Timing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Based on work done under Microcosm's recently completed Phase II SBIR program on X-ray pulsar based navigation (XNAV), relevant X-ray source characterization, X-ray...

  3. X-Ray Observations of XSS J12270-4859 in a New Low State: A Transformation to a Disk-free Rotation-powered Pulsar Binary

    NARCIS (Netherlands)

    Bogdanov, S.; Patruno, A.; Archibald, A.M.; Bassa, C.; Hessels, J.W.T.; Janssen, G.H.; Stappers, B.W.

    2014-01-01

    We present XMM-Newton and Chandra observations of the low-mass X-ray binary XSS J12270-4859, which experienced a dramatic decline in optical/X-ray brightness at the end of 2012, indicative of the disappearance of its accretion disk. In this new state, the system exhibits previously absent

  4. Discovery of Psr J1227-4853: A Transition from a Low-mass X-Ray Binary to a Redback Millisecond Pulsar

    NARCIS (Netherlands)

    Roy, J.; Ray, P.S.; Bhattacharyya, B.; Stappers, B.; Chengalur, J.N.; Deneva, J.; Camilo, F.; Johnson, T.J.; Wolff, M.; Hessels, J.W.T.; Bassa, C.G.; Keane, E.F.; Ferrara, E.C.; Harding, A.K.; Wood, K.S.

    2015-01-01

    XSS J12270−4859 is an X-ray binary associated with the Fermi Large Area Telescope gamma-ray source 1FGL J1227.9−4852. In 2012 December, this source underwent a transition where the X-ray and optical luminosity dropped and the spectral signatures of an accretion disk disappeared. We report the

  5. Strain, size and composition of InAs quantum sticks, embedded in InP, determined via X-ray anomalous diffraction and diffraction anomalous fine structure in grazing incidence

    International Nuclear Information System (INIS)

    Letoublon, A.; Favre-Nicolin, V.; Renevier, H.; Proietti, M.G.; Monat, C.; Gendry, M.; Marty, O.; Priester, C.

    2005-01-01

    We report on the study of strain, size and composition of small-size encapsulated semiconductor nanostructures. We show that the partial structure factor of As atoms in InAs stick-like nanostructures (quantum sticks), embedded in InP, can be directly extracted from grazing incidence anomalous X-ray diffraction maps at the As K-edge. We have recovered the average height and strain of the islands and determined their composition. The average height of the quantum sticks (QSs), as deduced from the width of the structure factor profile is 2.54 nm. The InAs out of plane deformation, relative to InP, is equal to 6.1%. Fixed-Q anomalous diffraction spectra, measured at the As K-edge, in grazing incidence provide clear evidence of pure InAs QSs. This is confirmed by the analysis of the diffraction anomalous fine structure (DAFS) that also gives a direct way to recover the strain accomodation inside the quantum sticks. Finite difference method calculations reproduce well the diffraction data. Chemical mixing at interfaces is at most 1 ML. This paper shows that ultimate application of anomalous diffraction and DAFS together with reciprocal space maps is a powerful method to sudy the structural properties of nanostructures

  6. X-ray diagnostic in gas discharge

    International Nuclear Information System (INIS)

    Chen Suhe; Wang Dalun; Cui Gaoxian; Wang Mei; Fu Yibei; Zhang Xinwei; Zhang Wushou

    1995-01-01

    X rays were observed when the anomalous phenomenon in the metal loaded with deuterium studied by the gas-discharge method. Therefore the X-ray energy spectra were measured by the absorption method, the specific X-ray approach and the NaI scintillation counter, while X-ray intensity was estimated by using 7 Li thermoluminescent foils. The X-ray average energy measured by the absorption method is 27.6 +- 2.1 keV, which is fitted within the error extent to 26.0 +-2.4 keV monoenergetic X rays measured by the NaI scintillation counter

  7. Complementary information on CdSe/ZnSe quantum dot local structure from extended X-ray absorption fine structure and diffraction anomalous fine structure measurements

    International Nuclear Information System (INIS)

    Piskorska-Hommel, E.; Holý, V.; Caha, O.; Wolska, A.; Gust, A.; Kruse, C.; Kröncke, H.; Falta, J.; Hommel, D.

    2012-01-01

    The extended X-ray absorption fine structure (EXAFS) and diffraction anomalous fine structure (DAFS) have been applied to investigate a local structure for the CdSe/ZnSe quantum dots grown by molecular beam epitaxy (MBE) and migration-enhanced epitaxy (MEE). The aim was to study the intermixing of Cd and Zn atoms, chemical compositions and strain induced by cap-layer. The EXAFS at the Cd K-edge and DAFS at the Se K-edge proved the intermixing of Cd and Zn atoms. The distances Cd–Se (2.61 Å) found from EXAFS and DAFS analysis for h 1 region is closer to that in bulk CdSe (2.62 Å). The DAFS analysis revealed the differences in the local structure in two investigated regions (i.e. different iso-strain volumes) on the quantum dots. It was found that the investigated areas differ in the Cd concentration. To explain the experimental results the theoretical calculation based on a full valence-force field (VFF) model was performed. The theoretical VFF model fully explains the experimental data.

  8. Orbital Evolution Measurement of the Accreting Millisecond X-ray ...

    Indian Academy of Sciences (India)

    powered millisecond X-ray pulsar SAX J1808.4–3658 using. X-ray data obtained during four outbursts of this source. Extensive obser- vations were made with the proportional counter array of the Rossi X-ray. Timing Explorer (RXTE) during the four ...

  9. Orbital Evolution Measurement of the Accreting Millisecond X-ray ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... We present results from a pulse timing analysis of the accretion-powered millisecond X-ray pulsar SAX J1808.4–3658 using X-ray data obtained during four outbursts of this source. Extensive observations were made with the proportional counter array of the Rossi X-ray Timing Explorer (RXTE) during the ...

  10. Skull x-ray

    Science.gov (United States)

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

  11. Neck x-ray

    Science.gov (United States)

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

  12. Radio emission from the X-ray pulsar Her X-1: a jet launched by a strong magnetic field neutron star?

    Science.gov (United States)

    van den Eijnden, J.; Degenaar, N.; Russell, T. D.; Miller-Jones, J. C. A.; Wijnands, R.; Miller, J. M.; King, A. L.; Rupen, M. P.

    2018-01-01

    Her X-1 is an accreting neutron star (NS) in an intermediate-mass X-ray binary. Like low-mass X-ray binaries (LMXBs), it accretes via Roche lobe overflow, but similar to many high-mass X-ray binaries containing a NS; Her X-1 has a strong magnetic field and slow spin. Here, we present the discovery of radio emission from Her X-1 with the Very Large Array. During the radio observation, the central X-ray source was partially obscured by a warped disc. We measure a radio flux density of 38.7 ± 4.8 μJy at 9 GHz but cannot constrain the spectral shape. We discuss possible origins of the radio emission, and conclude that coherent emission, a stellar wind, shocks and a propeller outflow are all unlikely explanations. A jet, as seen in LMXBs, is consistent with the observed radio properties. We consider the implications of the presence of a jet in Her X-1 on jet formation mechanisms and on the launching of jets by NSs with strong magnetic fields.

  13. The NuSTAR Hard X-Ray Survey of the Norma Arm Region

    DEFF Research Database (Denmark)

    Fornasini, Francesca M.; Tomsick, John A.; Hong, JaeSub

    2017-01-01

    brightest sources were previously identified as a low-mass X-ray binary, high-mass X-ray binary, and pulsar wind nebula. Based on their X-ray properties and multiwavelength counterparts, we identify the likely nature of the other sources as two colliding wind binaries, three pulsar wind nebulae, a black...

  14. Competitive adsorption of strontium and fulvic acid at the muscovite-solution interface observed with resonant anomalous X-ray reflectivity

    Science.gov (United States)

    Lee, Sang Soo; Park, Changyong; Fenter, Paul; Sturchio, Neil C.; Nagy, Kathryn L.

    2010-03-01

    Molecular-scale distributions of Sr 2+ and fulvic acid (FA) adsorbed on the muscovite (0 0 1) surface were investigated using in situ specular X-ray reflectivity (XR) and resonant anomalous X-ray reflectivity (RAXR). The total amount of Sr 2+ adsorbed from a 1 × 10 -2 mol/kg SrCl 2 and 100 mg/kg Elliott Soil Fulvic Acid II (ESFA II) solution at pH 5.5 compensated 81 ± 5% of the muscovite surface charge, less than previously measured (118 ± 5%) in an ESFA II-free solution with the same Sr concentration and pH. Inner-sphere (IS) and outer-sphere (OS) Sr 2+ constituted 87% of the total adsorbed species in IS:OS proportions of 19:81 compared to 42:58 in the solution without FA, suggesting that adsorbed FA competes with the IS Sr 2+ for surface sites. The coverage of both IS and OS Sr 2+ decreased even more in a pH 3.5 solution containing the same concentration of FA and 0.5 × 10 -2 mol/kg Sr(NO 3) 2, whereas a significant amount of Sr 2+ accumulated farther from the surface in the FA layer. The amount of Sr 2+ incorporated in the ˜10 Å thick FA layer decreased by 79% with decreasing FA concentration (100 → 1 mg/kg) and increasing Sr 2+ concentration (0.5 × 10 -2 → 1 × 10 -2 mol/kg) and pH (3.5 → 3.6). These results indicate not only that adsorbed FA molecules (and perhaps also H 3O +) displace Sr 2+ near the muscovite surface, but also that the sorbed FA film provides binding sites for additional Sr 2+ away from the surface. When a muscovite crystal pre-coated with FA after reaction in a 100 mg/kg ESFA II solution for 50 h was subsequently reacted with a 0.5 × 10 -2 mol/kg Sr(NO 3) 2 and 100 mg/kg ESFA II solution at pH 3.7, a significant fraction of Sr 2+ was distributed in the outer part of the FA film similar to that observed on fresh muscovite reacted at pH 3.5 with a pre-mixed Sr-FA solution at the same concentrations. However, this Sr 2+ sorbed in the pre-adsorbed organic film was more widely distributed and had a lower coverage, suggesting that

  15. A comparison of the merits of isotopic substitution in neutron small-angle scattering and anomalous X-ray scattering for the evaluation of partial structure functions in a ternary alloy

    International Nuclear Information System (INIS)

    Simon, J.P.; Grenoble-1 Univ., 38; Lyon, O.; Paris-11 Univ., 91 - Orsay; Fontaine, D. de

    1985-01-01

    Solute partitioning during decomposition of a ternary alloy may be evaluated through the inversion of a system of linear equations, obtained by performing at least three independent small-angle scattering experiments. The merits of neutron scattering (with isotopic contrast) and of anomalous X-ray scattering (near the absorption edges) are compared. It appears that neutron scattering, although having good contrast, is not suited to these studies since slight structural differences between the three samples may lead to erroneous results. On the other hand, the use of the same sample in anomalous scattering avoids this problem, but with the drawback of a more ill-conditioned system. Nevertheless, the possibility of performing more than three anomalous experiments may improve the results and a new analysis of data is proposed. (orig.)

  16. X-ray Emission from the Guitar Nebula

    OpenAIRE

    Romani, Roger W.; Cordes, James M.; Yadigaroglu, I. -A.

    1997-01-01

    We have detected weak soft X-ray emission from the Pulsar Wind Nebula trailing the high velocity star PSR 2224+65 (the `Guitar Nebula'). This X-ray flux gives evidence of \\gamma~10^7 eV particles in the pulsar wind and constrains the properties of the post-shock flow. The X-ray emission is most easily understood if the shocked pulsar wind is partly confined in the nebula and if magnetic fields in this zone can grow to near equipartition values.

  17. X-Ray Emission from the Guitar Nebula

    Science.gov (United States)

    Romani, Roger W.; Cordes, James M.; Yadigaroglu, I.-A.

    1997-01-01

    We have detected weak soft X-ray emission from the pulsar wind nebula trailing the high-velocity star PSR 2224+65 (the "Guitar Nebula"). This X-ray flux gives evidence of gamma approximately 10(exp 7) eV particles in the pulsar wind and constrains the properties of the postshock flow. The X-ray emission is most easily understood if the shocked pulsar wind is partly confined in the nebula and if magnetic fields in this zone can grow to near-equipartition values.

  18. Cosmic x ray physics

    Science.gov (United States)

    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.

  19. X-Ray

    Science.gov (United States)

    ... enema. What you can expect During the X-ray X-rays are performed at doctors' offices, dentists' offices, ... as those using a contrast medium. Your child's X-ray Restraints or other techniques may be used to ...

  20. Chest x-ray

    Science.gov (United States)

    Chest radiography; Serial chest x-ray; X-ray - chest ... There is low radiation exposure. X-rays are monitored and regulated to provide the minimum amount of radiation exposure needed to produce the image. Most ...

  1. Abdominal x-ray

    Science.gov (United States)

    Abdominal film; X-ray - abdomen; Flat plate; KUB x-ray ... There is low radiation exposure. X-rays are monitored and regulated to provide the minimum amount of radiation exposure needed to produce the image. Most ...

  2. X-ray astronomy

    International Nuclear Information System (INIS)

    Giacconi, R.; Gursky, H.

    1974-01-01

    This text contains ten chapters and three appendices. Following an introduction, chapters two through five deal with observational techniques, mechanisms for the production of x rays in a cosmic setting, the x-ray sky and solar x-ray emission. Chapters six through ten include compact x-ray sources, supernova remnants, the interstellar medium, extragalactic x-ray sources and the cosmic x-ray background. Interactions of x rays with matter, units and conversion factors and a catalog of x-ray sources comprise the three appendices. (U.S.)

  3. Near edge x-ray spectroscopy theory

    International Nuclear Information System (INIS)

    1994-01-01

    We propose to develop a quantitative theory of x-ray spectroscopies in the near edge region, within about 100 eV of threshold. These spectroscopies include XAFS (X-ray absorption fine structure), photoelectron diffraction (PD), and diffraction anomalous fine structure (DAFS), all of which are important tools for structural studies using synchrotron radiation x-ray sources. Of primary importance in these studies are many-body effects, such as the photoelectron self-energy, and inelastic losses. A better understanding of these quantities is needed to obtain theories without adjustable parameters. We propose both analytical and numerical calculations, the latter based on our x-ray spectroscopy codes FEFF

  4. Chest X-Ray

    Medline Plus

    Full Text Available ... about chest radiography also known as chest x-rays. Chest x-rays are the most commonly performed x-ray exams and use a very small dose of ... of the inside of the chest. A chest x-ray is used to evaluate the lungs, heart and ...

  5. Stellar X-Ray Polarimetry

    Science.gov (United States)

    Swank, J.

    2011-01-01

    Most of the stellar end-state black holes, pulsars, and white dwarfs that are X-ray sources should have polarized X-ray fluxes. The degree will depend on the relative contributions of the unresolved structures. Fluxes from accretion disks and accretion disk corona may be polarized by scattering. Beams and jets may have contributions of polarized emission in strong magnetic fields. The Gravity and Extreme Magnetism Small Explorer (GEMS) will study the effects on polarization of strong gravity of black holes and strong magnetism of neutron stars. Some part of the flux from compact stars accreting from companion stars has been reflected from the companion, its wind, or accretion streams. Polarization of this component is a potential tool for studying the structure of the gas in these binary systems. Polarization due to scattering can also be present in X-ray emission from white dwarf binaries and binary normal stars such as RS CVn stars and colliding wind sources like Eta Car. Normal late type stars may have polarized flux from coronal flares. But X-ray polarization sensitivity is not at the level needed for single early type stars.

  6. X-ray sky

    International Nuclear Information System (INIS)

    Gruen, M.; Koubsky, P.

    1977-01-01

    The history is described of the discoveries of X-ray sources in the sky. The individual X-ray detectors are described in more detail, i.e., gas counters, scintillation detectors, semiconductor detectors, and the principles of X-ray spectrometry and of radiation collimation aimed at increased resolution are discussed. Currently, over 200 celestial X-ray sources are known. Some were identified as nebulae, in some pulsations were found or the source was identified as a binary star. X-ray bursts of novae were also observed. The X-ray radiation is briefly mentioned of spherical star clusters and of extragalactic X-ray sources. (Oy)

  7. Formation and Evolution of X-ray Binaries

    Science.gov (United States)

    Shao, Y.

    2017-07-01

    -donor mass plane increases with the increasing neutron star mass. This may help to explain why some millisecond pulsars with orbital periods longer than ˜ 60 d seem to have less massive white dwarfs than expected. Alternatively, some of these wide binary pulsars may be formed through mass transfer driven by planet/brown dwarf-involved common envelope evolution; (2) Some of the pulsars in compact binaries might have evolved from intermediate-mass X-ray binaries with an anomalous magnetic braking; (3) The equilibrium spin periods of neutron stars in low-mass X-ray binaries are in general shorter than the observed spin periods of binary pulsars by more than one order of magnitude, suggesting that either the simple equilibrium spin model does not apply, or there are other mechanisms/processes spinning down the neutron stars. In Chapter 4, angular momentum loss mechanisms in the cataclysmic variables below the period gap are presented. By considering several kinds of consequential angular momentum loss mechanisms, we find that neither isotropic wind from the white dwarf nor outflow from the L1 point can explain the extra angular momentum loss rate, while an ouflow from the L2 point or a circumbinary disk can effectively extract the angular momentum provided that ˜ 15%-45% of the transferred mass is lost from the binary. A more promising mechanism is a circumbinary disk exerting a gravitational torque on the binary. In this case the mass loss fraction can be as low as ≲ 10-3. In Chapter 5 we present a study on the population of ultraluminous X-ray sources with an accreting neutron star. Most ULXs are believed to be X-ray binary systems, but previous observational and theoretical studies tend to prefer a black hole rather than a neutron star accretor. The recent discovery of 1.37 s pulsations from the ULX M82 X-2 has established its nature as a magnetized neutron star. In this chapter we model the formation history of neutron star ULXs in an M82- or Milky Way-like galaxy, by

  8. Chandra ACIS-S imaging spectroscopy of anomalously faint X-ray emission from Comet 103P/Hartley 2 during the EPOXI encounter

    Science.gov (United States)

    Lisse, C. M.; Christian, D. J.; Wolk, S. J.; Dennerl, K.; Bodewits, D.; Combi, M. R.; Lepri, S. T.; Zurbuchen, T. H.; Li, J. Y.; Dello-Russo, N.; Belton, M. J. S.; Knight, M. M.

    2013-02-01

    We present results from the Chandra X-ray Observatory's characterization of the X-ray emission from Comet 103P/Hartley 2, in support of NASA's Deep Impact Extended close flyby of the comet on 04 November 2010. The comet was observed 4 times for a total on target time of ˜60 ks between the 17th of October and 16th of November 2010, with two of the visits occurring during the EPOXI close approach on 04 November and 05 November 2010. X-ray emission from 103P was qualitatively similar to that observed for collisionally thin Comets 2P/Encke (Lisse, C.M. et al. [2005]. Astrophys. J. 635, 1329-1347) and 9P/Tempel 1 (Lisse, C.M. et al. [2007]. Icarus 190, 391-405). Emission morphology offset sunward but asymmetrical from the nucleus and emission lines produced by charge exchange between highly stripped C, N, and O solar wind minor ions and coma neutral gas species were found. The comet was very under-luminous in the X-ray at all times, representing the 3rd faintest comet ever detected (LX = 1.1 ± 0.3 × 1014 erg s-1). The coma was collisionally thin to the solar wind at all times, allowing solar wind ions to flow into the inner coma and interact with the densest neutral coma gas. Localization of the X-ray emission in the regions of the major rotating gas jets was observed, consistent with the major source of cometary neutral gas species being icy coma dust particles. Variable spectral features due to changing solar wind flux densities and charge states were also seen. Modeling of the Chandra observations from the first three visits using observed gas production rates and ACE solar wind ion fluxes with a charge exchange mechanism for the emission is consistent with the temporal and spectral behavior expected for a slow, hot wind typical of low latitude emission from the solar corona interacting with the comet's neutral coma. The X-ray emission during the 4th visit on 16 November 2010 is similar to the unusual behavior seen for Comet 17P/Holmes in 2007 (Christian, D.J. et

  9. Neutron Stars in X-ray Binaries and their Environments

    Indian Academy of Sciences (India)

    The X-ray pulsars among the binary neutron stars provide excellent handle to make accurate measurement of the orbital parameters and thus also evolution of the binray orbits that take place over time scale of a fraction of a million years to tens of millions of years. The orbital period evolution of X-ray binaries have shown ...

  10. X-ray Optics Development at MSFC

    Science.gov (United States)

    Sharma, Dharma P.

    2017-01-01

    Development of high resolution focusing telescopes has led to a tremendous leap in sensitivity, revolutionizing observational X-ray astronomy. High sensitivity and high spatial resolution X-ray observations have been possible due to use of grazing incidence optics (paraboloid/hyperboloid) coupled with high spatial resolution and high efficiency detectors/imagers. The best X-ray telescope flown so far is mounted onboard Chandra observatory launched on July 23,1999. The telescope has a spatial resolution of 0.5 arc seconds with compatible imaging instruments in the energy range of 0.1 to 10 keV. The Chandra observatory has been responsible for a large number of discoveries and has provided X-ray insights on a large number of celestial objects including stars, supernova remnants, pulsars, magnetars, black holes, active galactic nuclei, galaxies, clusters and our own solar system.

  11. Anomalous metallic state with strong charge fluctuations in BaxTi8O16 +δ revealed by hard x-ray photoemission spectroscopy

    Science.gov (United States)

    Dash, S.; Kajita, T.; Okawa, M.; Saitoh, T.; Ikenaga, E.; Saini, N. L.; Katsufuji, T.; Mizokawa, T.

    2018-04-01

    We have studied a charge-orbital driven metal-insulator transition (MIT) in hollandite-type BaxTi8O16 +δ by means of hard x-ray photoemission spectroscopy (HAXPES). The Ti 2 p HAXPES indicates strong Ti3 +/Ti4 + charge fluctuation in the metallic phase above the MIT temperature. The metallic phase is characterized by a power-law spectral function near the Fermi level which would be a signature of bad metal with non-Drude polaronic behavior. The power-law spectral shape is associated with the large Seebeck coefficient of the metallic phase in BaxTi8O16 +δ .

  12. X-ray apparatus

    International Nuclear Information System (INIS)

    Sell, L.J.

    1981-01-01

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

  13. X-ray - skeleton

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003381.htm X-ray - skeleton To use the sharing features on this ... Degenerative bone conditions Osteomyelitis Risks There is low radiation exposure. X-rays machines are set to provide the smallest ...

  14. Dental x-rays

    Science.gov (United States)

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

  15. Chest X-Ray

    Medline Plus

    Full Text Available ... some concerns about chest x-rays. However, it’s important to consider the likelihood of benefit to your health. While a chest x-ray use a ... posted: How to Obtain and Share ...

  16. X-ray (image)

    Science.gov (United States)

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

  17. Chest X-Ray

    Medline Plus

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

  18. X-ray Transient Sources (Multifrequency Laboratories The Case of the Prototype A0535+26/HDE 245770

    Directory of Open Access Journals (Sweden)

    F. Giovannelli

    2011-01-01

    Full Text Available The goal of this paper is to discuss the behaviour of the X-ray transient source A0535+26 which is considered for historical reasons and for the huge amount of multifrequency data, spread over a period of 35 years, as the prototype of this class of objects. Transient sources are formed by a Be star — the primary — and a neutron star X-ray pulsar — the secondary — and constitute a sub-class of X-ray binary systems. We will emphasize the discovery of low-energy indicators of high-energy processes. They are UBVRI magnitudes and Balmer lines of the optical companion. Particular unusual activity of the primary star — usually at the periastron passage of the neutron star – indicates that an X-ray flare is drawing near. The shape and intensity of X-ray outbursts are dependent on the strength of the activity of the primary. We derive the optical orbital period of the system as 110.856 ± 0.02 days. By using the optical flare of December 5, 1981 (here after 811205-E that triggered the subsequent X-ray outburst of December 13, 1981, we derive the ephemeris of the system as JD Popt−outb = JD0 (2, 444, 944 ± n(110.856 ± 0.02. Thus the passage of the neutron star at the periastron occurs with a periodicity of 110.856 ± 0.02 days and the different kinds of X-ray outbursts of A0535+26 — following the definitions reported in the review by Giovannelli & Sabau-Graziati (1992 — occur just after ∼ 8 days. The delay between optical and X-ray outbursts is just the transit time of the material coming out from the optical companion to reach the neutron star X-ray pulsar. The occurrence of X-ray “normal outbursts”, “anomalous outbursts” or “casual outbursts” is dependent on the activity of the Be star: “quiet state: steady stellar wind”, “excited state: stellar wind plus puffs of material”, and “expulsion of a shell”, respectively. In the latter case, the primary manifests a strong optical activity and the consequent strong

  19. Flash X-ray

    International Nuclear Information System (INIS)

    Sato, Eiichi

    2003-01-01

    Generation of quasi-monochromatic X-ray by production of weakly ionized line plasma (flash X-ray), high-speed imaging by the X-ray and high-contrast imaging by the characteristic X-ray absorption are described. The equipment for the X-ray is consisted from the high-voltage power supply and condenser, turbo molecular pump, and plasma X-ray tube. The tube has a long linear anticathode to produce the line plasma and flash X-ray at 20 kA current at maximum. X-ray spectrum is measured by the imaging plate equipped in the computed radiography system after diffracted by a LiF single crystal bender. Cu anticathode generates sharp peaks of K X-ray series. The tissue images are presented for vertebra, rabbit ear and heart, and dog heart by X-ray fluoroscopy with Ce anticathode. Generation of K-orbit characteristic X-ray with extremely low bremsstrahung is to be attempted for medical use. (N.I.)

  20. The use of anomalous scattering of uranium for the determination of biological macromolecules structures - From hard to soft X-rays

    International Nuclear Information System (INIS)

    Chesne-Seck, M.L.

    2002-01-01

    In order to solve biological macromolecules structures, structure factor phases must be derived from the intensities diffracted by the crystal. The SAD and the MAD methods make use of variations in scattering factors measured at specific absorption edges of heavy atoms, bound to the protein. The phasing power depends on the occupancy of the binding sites and on the variations of the scattering factors at the absorption edge that is used. With uranyl, numerous sites with low occupancies are usually obtained. We used new colored uranyl complexes, which give higher occupancies, to solve de novo the lysozyme structure and an unknown structure. We have developed the use of the My absorption edge of uranium (λ = 3,5 Angstroms), where a variation of 120 electrons is observed in the scattering factors. With a helium atmosphere to limit the X-rays absorption, we have collected three data sets, on a single image. Data were processed both with 'classical' and specific programs. (author) [fr

  1. Design and development of grazing incidence x-ray mirrors

    Science.gov (United States)

    Zuo, Fuchang; Mei, Zhiwu; Ma, Tao; Deng, Loulou; Shi, Yongqiang; Li, Liansheng

    2016-01-01

    X-ray pulsar navigation has attracted extensive attentions from academy and engineering domains. The navigation accuracy is can be enhanced through design of X-ray mirrors to focus X-rays to a small detector. The Wolter-I optics, originally proposed based on a paraboloid mirror and a hyperboloid mirror for X-ray imaging, has long been widely developed and employed in X-ray observatory. Some differences, however, remain in the requirements on optics between astronomical X-ray observation and pulsar navigation. The simplified Wolter-I optics, providing single reflection by a paraboloid mirror, is more suitable for pulsar navigation. In this paper, therefore, the grazing incidence X-ray mirror was designed further based on our previous work, with focus on the reflectivity, effective area, angular resolution and baffles. To evaluate the performance of the manufactured mirror, the surface roughness and reflectivity were tested. The test results show that the grazing incidence mirror meets the design specifications. On the basis of this, the reflectivity of the mirror in the working bandwidth was extrapolated to evaluate the focusing ability of the mirror when it works together with the detector. The purpose of our current work to design and develop a prototype mirror was realized. It can lay a foundation and provide guidance for the development of multilayer nested X-ray mirror with larger effective area.

  2. 363. WE-Heraeus seminar on neutron stars and pulsars - 40 years after the discovery. Posters and contributed talks

    International Nuclear Information System (INIS)

    Becker, W.; Huang, H.H.

    2007-01-01

    The following topics were dealt with: X-ray observation of pulsars, gamma-ray observation of pulsars, radio observations of pulsars, theory of neutron stars and pulsars, AXPs, SGRs, and strange stars, gravitayional waves, analysis tools with software. (HSI)

  3. 363. WE-Heraeus seminar on neutron stars and pulsars - 40 years after the discovery. Posters and contributed talks

    Energy Technology Data Exchange (ETDEWEB)

    Becker, W.; Huang, H.H. (eds.)

    2007-07-01

    The following topics were dealt with: X-ray observation of pulsars, gamma-ray observation of pulsars, radio observations of pulsars, theory of neutron stars and pulsars, AXPs, SGRs, and strange stars, gravitayional waves, analysis tools with software. (HSI)

  4. Ultraluminous X-ray bursts in two ultracompact companions to nearby elliptical galaxies.

    Science.gov (United States)

    Irwin, Jimmy A; Maksym, W Peter; Sivakoff, Gregory R; Romanowsky, Aaron J; Lin, Dacheng; Speegle, Tyler; Prado, Ian; Mildebrath, David; Strader, Jay; Liu, Jifeng; Miller, Jon M

    2016-10-20

    A flaring X-ray source was found near the galaxy NGC 4697 (ref. 1). Two brief flares were seen, separated by four years. During each flare, the flux increased by a factor of 90 on a timescale of about one minute. There is no associated optical source at the position of the flares, but if the source was at the distance of NGC 4697, then the luminosities of the flares were greater than 10 39 erg per second. Here we report the results of a search of archival X-ray data for 70 nearby galaxies looking for similar flares. We found two ultraluminous flaring sources in globular clusters or ultracompact dwarf companions of parent elliptical galaxies. One source flared once to a peak luminosity of 9 × 10 40 erg per second; the other flared five times to 10 40 erg per second. The rise times of all of the flares were less than one minute, and the flares then decayed over about an hour. When not flaring, the sources appear to be normal accreting neutron-star or black-hole X-ray binaries, but they are located in old stellar populations, unlike the magnetars, anomalous X-ray pulsars or soft γ repeaters that have repetitive flares of similar luminosities.

  5. JEM-X observations of the Be/X-ray binary EXO 2030+375

    DEFF Research Database (Denmark)

    Nunez, S.M.; Reig, P.; Blay, P.

    2003-01-01

    We have used data from the Joint European Monitor (JEM-X) to perform an X-ray spectral and timing analysis of the 42-s transient pulsar EXO 2030+375 during an X-ray outburst. X-ray pulsations are clearly detected with an average pulse period of 41.66+/-0.05 s and an average pulse fraction of 60%....

  6. X-ray holography

    CERN Document Server

    Faigel, G; Belakhovsky, M; Marchesini, S; Bortel, G

    2003-01-01

    In the last decade holographic methods using hard X-rays were developed. They are able to resolve atomic distances, and can give the 3D arrangement of atoms around a selected element. Therefore, hard X-ray holography has potential applications in chemistry, biology and physics. In this article we give a general description of these methods and discuss the developments in the experimental technique. The capabilities of hard X-ray holography are demonstrated by examples.

  7. X-ray holography

    International Nuclear Information System (INIS)

    Faigel, G.; Tegze, M.; Belakhovsky, M.; Marchesini, S.; Bortel, G.

    2003-01-01

    In the last decade holographic methods using hard X-rays were developed. They are able to resolve atomic distances, and can give the 3D arrangement of atoms around a selected element. Therefore, hard X-ray holography has potential applications in chemistry, biology and physics. In this article we give a general description of these methods and discuss the developments in the experimental technique. The capabilities of hard X-ray holography are demonstrated by examples

  8. A Deep X-ray Survey of the Globular Cluster Omega Centauri

    Science.gov (United States)

    Henleywillis, Simon; Cool, Adrienne M.; Haggard, Daryl; Heinke, Craig; Callanan, Paul; Zhao, Yue

    2018-03-01

    We identify 233 X-ray sources, of which 95 are new, in a 222 ks exposure of Omega Centauri with the Chandra X-ray Observatory's ACIS-I detector. The limiting unabsorbed flux in the core is fX(0.5-6.0 keV) ≃ 3×10-16 erg s-1 cm-2 (Lx ≃ 1×1030 erg s-1 at 5.2 kpc). We estimate that ˜60 ± 20 of these are cluster members, of which ˜30 lie within the core (rc = 155 arcsec), and another ˜30 between 1-2 core radii. We identify four new optical counterparts, for a total of 45 likely identifications. Probable cluster members include 18 cataclysmic variables (CVs) and CV candidates, one quiescent low-mass X-ray binary, four variable stars, and five stars that are either associated with ω Cen's anomalous red giant branch, or are sub-subgiants. We estimate that the cluster contains 40 ± 10 CVs with Lx > 1031 erg s-1, confirming that CVs are underabundant in ω Cen relative to the field. Intrinsic absorption is required to fit X-ray spectra of six of the nine brightest CVs, suggesting magnetic CVs, or high-inclination systems. Though no radio millisecond pulsars (MSPs) are currently known in ω Cen, more than 30 unidentified sources have luminosities and X-ray colours like those of MSPs found in other globular clusters; these could be responsible for the Fermi-detected gamma-ray emission from the cluster. Finally, we identify a CH star as the counterpart to the second-brightest X-ray source in the cluster and argue that it is a symbiotic star. This is the first such giant/white dwarf binary to be identified in a globular cluster.

  9. Providing x-rays

    International Nuclear Information System (INIS)

    Mallozzi, P.J.; Epstein, H.M.

    1985-01-01

    This invention provides an apparatus for providing x-rays to an object that may be in an ordinary environment such as air at approximately atmospheric pressure. The apparatus comprises: means (typically a laser beam) for directing energy onto a target to produce x-rays of a selected spectrum and intensity at the target; a fluid-tight enclosure around the target; means for maintaining the pressure in the first enclosure substantially below atmospheric pressure; a fluid-tight second enclosure adjoining the first enclosure, the common wall portion having an opening large enough to permit x-rays to pass through but small enough to allow the pressure reducing means to evacuate gas from the first enclosure at least as fast as it enters through the opening; the second enclosure filled with a gas that is highly transparent to x-rays; the wall of the second enclosure to which the x-rays travel having a portion that is highly transparent to x-rays (usually a beryllium or plastic foil), so that the object to which the x-rays are to be provided may be located outside the second enclosure and adjacent thereto and thus receive the x-rays substantially unimpeded by air or other intervening matter. The apparatus is particularly suited to obtaining EXAFS (extended x-ray fine structure spectroscopy) data on a material

  10. Dietary iron-loaded rat liver haemosiderin and ferritin: in situ measurement of iron core nanoparticle size and cluster structure using anomalous small-angle x-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Bovell, Eliza; Buckley, Craig E.; Chua-anusorn, Wanida; Cookson, David; Kirby, Nigel; Saunders, Martin; St. Pierre, Timothy G. ((UWA)); ((Curtin U.)); ((ASRP))

    2009-03-16

    The morphology, particle size distribution and cluster structure of the hydrated iron(III) oxyhydroxide particles associated with haemosiderin and ferritin in dietary iron-loaded rat liver tissue have been investigated using transmission electron microscopy (TEM) and anomalous small-angle x-ray scattering (ASAXS). Rat liver tissue was removed from a series of female Porton rats which had been fed an iron-rich diet until sacrifice at various ages from 2-24 months. Hepatic iron concentrations ranged from 1 to 65 mg Fe g{sup -1} dry tissue. TEM studies showed both dispersed and clustered iron-containing nanoparticles. The dispersed particles were found to have mean sizes ({+-}standard deviation) of 54 {+-} 8 {angstrom} for the iron-loaded animals and 55 {+-} 7 {angstrom} for the controls. Superposition of particles in TEM images prevented direct measurement of nanoparticulate size in the clusters. The ASAXS data were modelled to provide a quantitative estimate of both the size and spacing of iron oxyhydroxide particles in the bulk samples. The modelling yielded close-packed particles with sizes of 60 to 78 {angstrom} which when corrected for anomalous scattering suggests sizes from 54 to 70 {angstrom}. Particle size distributions are of particular importance since they determine the surface iron to core iron ratios, which in turn are expected to be related to the molar toxicity of iron deposits in cells.

  11. Modeling the amorphous structure of mechanically alloyed Ti{sub 50}Ni{sub 25}Cu{sub 25} using anomalous wide-angle x-ray scattering and reverse Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Lima, J.C. de, E-mail: fsc1jcd@fisica.ufsc.br [Departamento de Física, Universidade Federal de Santa Catarina, Campus Universitário Trindade, S/N, C.P. 476, 88040-900 Florianópolis, Santa Catarina (Brazil); Poffo, C.M. [Departamento de Engenharia Mecânica, Universidade Federal de Santa Catarina, Campus Universitário Trindade, S/N, C.P. 476, 88040-900 Florianópolis, Santa Catarina (Brazil); Departamento de Física, Universidade Federal do Amazonas, 3000 Japiim, 69077-000 Manaus, Amazonas (Brazil); Souza, S.M. [Departamento de Física, Universidade Federal do Amazonas, 3000 Japiim, 69077-000 Manaus, Amazonas (Brazil); Machado, K.D. [Departamento de Física, Centro Politécnico, Universidade Federal do Paraná, 81531-990 Curitiba, Paraná (Brazil); Trichês, D.M. [Departamento de Física, Universidade Federal do Amazonas, 3000 Japiim, 69077-000 Manaus, Amazonas (Brazil); Grandi, T.A. [Departamento de Física, Universidade Federal de Santa Catarina, Campus Universitário Trindade, S/N, C.P. 476, 88040-900 Florianópolis, Santa Catarina (Brazil); Biasi, R.S. de [Seção de Engenharia Mecânica e de Materiais, Instituto Militar de Engenharia, 22290-270 Rio de Janeiro, RJ (Brazil)

    2013-09-01

    An amorphous Ti{sub 50}Ni{sub 25}Cu{sub 25} alloy was produced by 19 h of mechanical alloying. Anomalous wide angle x-ray scattering data were collected at six energies and six total scattering factors were obtained. By considering the data collected at two energies close to the Ni and Cu K edges, two differential anomalous scattering factors about the Ni and Cu atoms were obtained, showing that the chemical environments around these atoms are different. Eight factors were used as input data to the reverse Monte Carlo method used to compute the partial structure factors S{sub Ti3Ti}(K), S{sub Ti–Cu}(K), S{sub Ti–Ni}(K), S{sub Cu3Cu}(K), S{sub Cu–Ni}(K) and S{sub Ni–Ni}(K) and the partial pair distribution functions G{sub Ti3Ti}(r), G{sub Ti–Cu}(r), G{sub Ti–Ni}(r), G{sub Cu3Cu}(r), G{sub Cu–Ni}(r) and G{sub Ni–Ni}(r). From the RMC final atomic configuration and G{sub ij}(r) functions, the coordination numbers and interatomic atomic distances for the first neighbors were determined.

  12. Extremity x-ray

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003461.htm Extremity x-ray To use the sharing features on this page, ... in the body Risks There is low-level radiation exposure. X-rays are monitored and regulated to provide the ...

  13. Chest X-Ray

    Medline Plus

    Full Text Available ... loose, comfortable clothing. You may be asked to change into a gown. You may have some concerns about chest x-rays. However, it’s important to consider the likelihood of benefit to your health. While a chest x-ray use a tiny ...

  14. Chest X-Ray

    Medline Plus

    Full Text Available ... by Image/Video Gallery Your Radiologist Explains Chest X-ray Transcript Welcome to Radiology Info dot org! Hello, ... d like to talk with you about chest radiography also known as chest x-rays. Chest x- ...

  15. Insights from soft X-rays

    DEFF Research Database (Denmark)

    Raaf, Jennifer; Issinger, Olaf-Georg; Niefind, Karsten

    2008-01-01

    The diffraction pattern of a protein crystal is normally a product of the interference of electromagnetic waves scattered by electrons of the crystalline sample. The diffraction pattern undergoes systematic changes in case additionally X-ray absorption occurs, meaning if the wavelength of the pri......The diffraction pattern of a protein crystal is normally a product of the interference of electromagnetic waves scattered by electrons of the crystalline sample. The diffraction pattern undergoes systematic changes in case additionally X-ray absorption occurs, meaning if the wavelength...... of the primary X-ray beam is relatively close to the absorption edge of selected elements of the sample. The resulting effects are summarized as "anomalous dispersion" and can be always observed with "soft" X-rays (wavelength around 2 A) since they match the absorption edges of sulfur and chlorine...

  16. X-ray generator

    International Nuclear Information System (INIS)

    Dawson, J.M.

    1976-01-01

    An apparatus and a method are described for producing coherent secondary x-rays that are controlled as to direction by illuminating a mixture of high z and low z gases with an intense burst of primary x-rays. The primary x-rays are produced with a laser activated plasma, and these x-rays strip off the electrons of the high z atoms in the lasing medium, while the low z atoms retain their electrons. The neutral atoms transfer electrons to highly excited states of the highly stripped high z ions giving an inverted population which produces the desired coherent x-rays. In one embodiment, a laser, light beam provides a laser spark that produces the intense burst of coherent x-rays that illuminates the mixture of high z and low z gases, whereby the high z atoms are stripped while the low z ones are not, giving the desired mixture of highly ionized and neutral atoms. Means for magnetically confining and stabilizing the plasma are disclosed for controlling the direction of the x-rays

  17. X-ray crystallography

    Science.gov (United States)

    2001-01-01

    X-rays diffracted from a well-ordered protein crystal create sharp patterns of scattered light on film. A computer can use these patterns to generate a model of a protein molecule. To analyze the selected crystal, an X-ray crystallographer shines X-rays through the crystal. Unlike a single dental X-ray, which produces a shadow image of a tooth, these X-rays have to be taken many times from different angles to produce a pattern from the scattered light, a map of the intensity of the X-rays after they diffract through the crystal. The X-rays bounce off the electron clouds that form the outer structure of each atom. A flawed crystal will yield a blurry pattern; a well-ordered protein crystal yields a series of sharp diffraction patterns. From these patterns, researchers build an electron density map. With powerful computers and a lot of calculations, scientists can use the electron density patterns to determine the structure of the protein and make a computer-generated model of the structure. The models let researchers improve their understanding of how the protein functions. They also allow scientists to look for receptor sites and active areas that control a protein's function and role in the progress of diseases. From there, pharmaceutical researchers can design molecules that fit the active site, much like a key and lock, so that the protein is locked without affecting the rest of the body. This is called structure-based drug design.

  18. X-ray apparatus

    International Nuclear Information System (INIS)

    Bernstein, S.; Stagg, L.; Lambert, T.W.; Griswa, P.J.

    1976-01-01

    A patient support system for X-ray equipment in arteriographic studies of the heart is described in detail. The support system has been designed to overcome many of the practical problems encountered in using previous types of arteriographic X-ray equipment. The support system is capable of horizontal movement and, by a series of shafts attached to the main support system, the X-ray source and image intensifier or detector may be rotated through the same angle. The system is highly flexible and details are given of several possible operational modes. (U.K.)

  19. X-ray detector

    International Nuclear Information System (INIS)

    Whetten, N.R.; Houston, J.M.

    1977-01-01

    An ionization chamber for use in determining the spatial distribution of x-ray photons in tomography systems comprises a plurality of substantially parallel, planar anodes separated by parallel, planar cathodes and enclosed in a gas of high atomic weight at a pressure from approximately 10 atmospheres to approximately 50 atmospheres. The cathode and anode structures comprise metals which are substantially opaque to x-ray radiation and thereby tend to reduce the resolution limiting effects of x-ray fluoresence in the gas. In another embodiment of the invention the anodes comprise parallel conductive bars disposed between two planar cathodes. Guard rings eliminate surface leakage currents between adjacent electrodes. 8 figures

  20. Bone X-Ray (Radiography)

    Medline Plus

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

  1. Panoramic Dental X-Ray

    Science.gov (United States)

    ... Resources Professions Site Index A-Z Panoramic Dental X-ray Panoramic dental x-ray uses a very small ... limitations of Panoramic X-ray? What is Panoramic X-ray? Panoramic radiography , also called panoramic x-ray , is ...

  2. Bone X-Ray (Radiography)

    Medline Plus

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

  3. Bone X-Ray (Radiography)

    Science.gov (United States)

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

  4. Abdomen X-Ray (Radiography)

    Science.gov (United States)

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

  5. X-Ray Exam: Hip

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español X-Ray Exam: Hip KidsHealth / For Parents / X-Ray Exam: ... darker. An X-ray technician takes the X-rays. An X-ray technician in the radiology department of a ...

  6. Bone X-Ray (Radiography)

    Medline Plus

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

  7. Lumbosacral spine x-ray

    Science.gov (United States)

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

  8. Bone X-Ray (Radiography)

    Medline Plus

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

  9. Chest X-Ray

    Medline Plus

    Full Text Available ... Radiology and You Take our survey Sponsored by Image/Video Gallery Your Radiologist Explains Chest X-ray ... posted: How to Obtain and Share Your Medical Images Movement Disorders Video: The Basketball Game: An MRI ...

  10. X-ray tubes

    International Nuclear Information System (INIS)

    Young, R.W.

    1979-01-01

    A form of x-ray tube is described which provides satisfactory focussing of the electron beam when the beam extends for several feet from gun to target. Such a tube can be used for computerised tomographic scanning. (UK)

  11. Chest X-Ray

    Medline Plus

    Full Text Available ... Site Index A-Z Spotlight February is American Heart Month Recently posted: Carotid Intima-Media Thickness Test ... x-ray is used to evaluate the lungs, heart and chest wall and may be used to ...

  12. Chest X-Ray

    Medline Plus

    Full Text Available ... Abdominal Ultrasound Video: Pelvic Ultrasound Medical Imaging Costs Radiology and You Take our survey Sponsored by Image/ ... Radiologist Explains Chest X-ray Transcript Welcome to Radiology Info dot org! Hello, I’m Dr. Geoffrey ...

  13. Chest X-Ray

    Medline Plus

    Full Text Available ... exams and use a very small dose of ionizing radiation to produce pictures of the inside of the ... chest x-ray use a tiny dose of ionizing radiation, the benefit of an accurate diagnosis far outweighs ...

  14. Chest X-Ray

    Medline Plus

    Full Text Available ... accurate diagnosis far outweighs any risk. For more information about chest x-rays, visit Radiology Info dot ... Inc. (RSNA). To help ensure current and accurate information, we do not permit copying but encourage linking ...

  15. Chest X-Ray

    Medline Plus

    Full Text Available ... and You Take our survey Sponsored by Image/Video Gallery Your Radiologist Explains Chest X-ray Transcript ... Carotid Intima-Media Thickness Test Medical Imaging Costs Video: Abdominal Ultrasound Video: Pelvic Ultrasound Radiology and You ...

  16. Chest X-Ray

    Medline Plus

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

  17. Chest X-Ray

    Medline Plus

    Full Text Available ... chest x-ray is used to evaluate the lungs, heart and chest wall and may be used ... diagnose and monitor treatment for a variety of lung conditions such as pneumonia, emphysema and cancer. A ...

  18. Chest X-Ray

    Medline Plus

    Full Text Available ... and use a very small dose of ionizing radiation to produce pictures of the inside of the ... x-ray use a tiny dose of ionizing radiation, the benefit of an accurate diagnosis far outweighs ...

  19. Chest X-Ray

    Medline Plus

    Full Text Available ... Index A-Z Spotlight March is National Colorectal Cancer Awareness Month Recently posted: Carotid Intima-Media Thickness ... of lung conditions such as pneumonia, emphysema and cancer. A chest x-ray requires no special preparation. ...

  20. Chest X-Ray

    Medline Plus

    Full Text Available ... Index A-Z Spotlight March is National Colorectal Cancer Awareness Month Recently posted: How to Obtain and ... of lung conditions such as pneumonia, emphysema and cancer. A chest x-ray requires no special preparation. ...

  1. Chest X-Ray

    Medline Plus

    Full Text Available ... Index A-Z Spotlight March is National Colorectal Cancer Awareness Month Recently posted: Video: The Basketball Game: ... of lung conditions such as pneumonia, emphysema and cancer. A chest x-ray requires no special preparation. ...

  2. Geriatric Pulsar Still Kicking

    Science.gov (United States)

    2009-02-01

    The oldest isolated pulsar ever detected in X-rays has been found with NASA's Chandra X-ray Observatory. This very old and exotic object turns out to be surprisingly active. The pulsar, PSR J0108-1431 (J0108 for short) is about 200 million years old. Among isolated pulsars -- ones that have not been spun-up in a binary system -- it is over 10 times older than the previous record holder with an X-ray detection. At a distance of 770 light years, it is one of the nearest pulsars known. Pulsars are born when stars that are much more massive than the Sun collapse in supernova explosions, leaving behind a small, incredibly weighty core, known as a neutron star. At birth, these neutron stars, which contain the densest material known in the Universe, are spinning rapidly, up to a hundred revolutions per second. As the rotating beams of their radiation are seen as pulses by distant observers, similar to a lighthouse beam, astronomers call them "pulsars". Astronomers observe a gradual slowing of the rotation of the pulsars as they radiate energy away. Radio observations of J0108 show it to be one of the oldest and faintest pulsars known, spinning only slightly faster than one revolution per second. The surprise came when a team of astronomers led by George Pavlov of Penn State University observed J0108 in X-rays with Chandra. They found that it glows much brighter in X-rays than was expected for a pulsar of such advanced years. People Who Read This Also Read... Chandra Data Reveal Rapidly Whirling Black Holes Milky Way’s Giant Black Hole Awoke from Slumber 300 Years Ago Erratic Black Hole Regulates Itself Celebrate the International Year of Astronomy Some of the energy that J0108 is losing as it spins more slowly is converted into X-ray radiation. The efficiency of this process for J0108 is found to be higher than for any other known pulsar. "This pulsar is pumping out high-energy radiation much more efficiently than its younger cousins," said Pavlov. "So, although it

  3. X-Ray Lasers

    Science.gov (United States)

    Eder, David C.

    1998-05-01

    We provide an overview of the status of x-ray laser development worldwide with particular attention given to activities at LLNL. Since the demonstration of x-ray lasing 14 years ago there has been major progress in achieving shorter wavelengths, higher energies per pulse, higher efficiency, shorter pulse durations, etc. Original x-ray lasers used large kJ class lasers to achieve lasing in mid-Z materials with electron collisional pumping in the highly stripped ion being the most successful process for populating the upper-laser state. The two most common electron configurations for these collisional x-ray lasers are Ne-like and Ni-like ions. Through the use of prepulses and short picosecond driving pulses, transient collisional x-ray lasing schemes have been demonstrated using lasers with only a few Joules per pulse. An interesting aspect of these lasers is the time lag in reaching ionization equilibrium helps in obtaining high gain coefficients. A different approach to x-ray lasing is also being studied where lasing occurs in a singly ionized ion following innershell photoionization. The major requirement of the driving laser in this case is an ultrashort pulse duration (rise time to achieve lasing prior to collisional ionization of outershell electrons. In the area of applications, most of the work has been for single pulse experiments such as plasma and biological imaging. However, many of the new x-ray lasers achieve high average power by having a reasonable repetition rate of order 10 Hz and we briefly discuss relevant applications for these x-ray lasers. This work performed under the auspices of US DOE by LLNL under Contract No. W-7405-Eng-48.

  4. X-Ray Optics

    Science.gov (United States)

    1990-01-01

    samples. Another exciting application of microbeam of x-rays is in that of high pressure x-ray diffraction from small samples. Along this line, Yan...will be presented by Jonathan in February at the Physics and Chemistry of Semiconductor Interfaces conference and in March at the American Physical...VUV9 conference this summer. Jeff has also worked on developing software that makes use of the scattering factor tables for both microvax and IBM PC

  5. Low Mass X-ray Binary 4U1705-44 Exiting an Extended High X-ray State

    Science.gov (United States)

    Phillipson, Rebecca; Boyd, Patricia T.; Smale, Alan P.

    2017-09-01

    The neutron-star low-mass X-ray binary 4U1705-44, which exhibited high amplitude long-term X-ray variability on the order of hundreds of days during the 16-year continuous monitoring by the RXTE ASM (1995-2012), entered an anomalously long high state in July 2012 as observed by MAXI (2009-present).

  6. Bone X-Ray (Radiography)

    Medline Plus

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

  7. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... of knee x-rays. A portable x-ray machine is a compact apparatus that can be taken ... of the body being examined, an x-ray machine produces a small burst of radiation that passes ...

  8. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... are the limitations of Bone X-ray (Radiography)? What is Bone X-ray (Radiography)? An x-ray ( ... leg (shin), ankle or foot. top of page What are some common uses of the procedure? A ...

  9. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... holds the x-ray film or image recording plate . Sometimes the x-ray is taken with the ... an x-ray film holder or image recording plate is placed beneath the patient. top of page ...

  10. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... standards used by radiology professionals. Modern x-ray systems have very controlled x-ray beams and dose ... Medicine Radiation Safety How to Read Your Radiology Report Images related to X-ray (Radiography) - Bone Sponsored ...

  11. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... that might interfere with the x-ray images. Women should always inform their physician and x-ray ... Safety page for more information about radiation dose. Women should always inform their physician or x-ray ...

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

    NARCIS (Netherlands)

    de Groot, F.M.F.

    2016-01-01

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

  13. X-ray astronomy

    International Nuclear Information System (INIS)

    Giacconi, R.; Setti, G.

    1980-01-01

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

  14. X-ray tube

    International Nuclear Information System (INIS)

    Webley, R.S.

    1975-01-01

    The object of the invention described is to provide an X-ray tube providing a scanned X-ray output which does not require a scanned electron beam. This is obtained by an X-ray tube including an anode which is rotatable about an axis, and a source of a beam of energy, for example an electron beam, arranged to impinge on a surface of the anode to generate X-radiation substantially at the region of incidence on the anode surface. The anode is rotatable about the axis to move the region of incidence over the surface. The anode is so shaped that the rotation causes the region of incidence to move in a predetermined manner relative to fixed parts of the tube so that the generated X-radiation is scanned in a predetermined manner relative to the tube. (UK)

  15. Station Explorer for X-Ray Timing and Navigation Technology (SEXTANT)

    Data.gov (United States)

    National Aeronautics and Space Administration — Use millisecond period X-ray emitting neutron stars (Millisecond Pulsars) as beacons to enable GPS-like autonomous navigation anywhere in Solar System and beyond....

  16. Celestial X-ray Source Modeling and Catalogues for Spacecraft Navigation and Timing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Microcosm X-ray pulsar-based navigation and timing (XNAV) team will provide the software and modeling infrastructure for NASA to support XNAV operations,...

  17. X-Ray Exam: Pelvis

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español X-Ray Exam: Pelvis KidsHealth / For Parents / X-Ray Exam: ... Ray Exam: Hip Broken Bones Getting an X-ray (Video) X-Ray (Video) View more Partner Message About Us ...

  18. X-Ray Exam: Forearm

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español X-Ray Exam: Forearm KidsHealth / For Parents / X-Ray Exam: ... Muscles, and Joints Broken Bones Getting an X-ray (Video) X-Ray (Video) View more Partner Message About Us ...

  19. X-Ray Exam: Foot

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español X-Ray Exam: Foot KidsHealth / For Parents / X-Ray Exam: ... Muscles, and Joints Broken Bones Getting an X-ray (Video) X-Ray (Video) View more Partner Message About Us ...

  20. X-Ray Exam: Wrist

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español X-Ray Exam: Wrist KidsHealth / For Parents / X-Ray Exam: ... Muscles, and Joints Broken Bones Getting an X-ray (Video) X-Ray (Video) View more Partner Message About Us ...

  1. Thoracic spine x-ray

    Science.gov (United States)

    Vertebral radiography; X-ray - spine; Thoracic x-ray; Spine x-ray; Thoracic spine films; Back films ... There is low radiation exposure. X-rays are monitored and regulated to provide the minimum amount of radiation exposure needed to produce the image. Most ...

  2. X-Ray Exam: Finger

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español X-Ray Exam: Finger KidsHealth / For Parents / X-Ray Exam: ... Muscles, and Joints Broken Bones Getting an X-ray (Video) X-Ray (Video) View more Partner Message About Us ...

  3. Subluminous X-ray binaries

    NARCIS (Netherlands)

    Armas Padilla, M.

    2013-01-01

    The discovery of the first X-ray binary, Scorpius X-1, by Giacconi et al. (1962), marked the birth of X-ray astronomy. Following that discovery, many additional X-ray sources where found with the first generation of X-ray rockets and observatories (e.g., UHURU and Einstein). The short-timescale

  4. X-ray detector

    International Nuclear Information System (INIS)

    Houston, J.M.; Whetten, N.R.

    1981-01-01

    An ionization chamber for use in determining the spatial distribution of x-ray photons in tomography systems comprises a plurality of substantially parallel, planar anodes separated by parallel, planar cathodes and enclosed in a gas of high atomic weight at a pressure from approximately 10 atmospheres to approximately 50 atmospheres. The cathode and anode structures comprise metals which are substantially opaque to x-ray radiation and thereby tend to reduce the resolution limiting effects of xray fluoresence in the gas. In another embodiment of the invention the anodes comprise parallel conductive bars disposed between two planar cathodes. Guard rings eliminate surface leakage currents between adjacent electrodes

  5. X-ray masks

    International Nuclear Information System (INIS)

    Greenwood, J.C.; Satchell, D.W.

    1984-01-01

    In semiconductor manufacture, where X-ray irradiation is used, a thin silicon membrane can be used as an X-ray mask. This membrane has areas on which are patterns to define the regions to be irradiated. These regions are of antireflection material. With the thin, in the order of 3 microns, membranes used, fragility is a problem. Hence a number of ribs of silicon are formed integral with the membrane, and which are relatively thick, 5 to 10 microns. The ribs may be formed by localised deeper boron deposition followed by a selective etch. (author)

  6. Flash x-ray

    International Nuclear Information System (INIS)

    Johnson, Q.; Pellinen, D.

    1976-01-01

    The complementary techniques of flash x-ray radiography (FXR) and flash x-ray diffraction (FXD) provide access to a unique domain in nondestructive materials testing. FXR is useful in studies of macroscopic properties during extremely short time intervals, and FXD, the newer technique, is used in studies of microscopic properties. Although these techniques are similar in many respects, there are some substantial differences. FXD generally requires low-voltage, line-radiation sources and extremely accurate timing; FXR is usually less demanding. Phenomena which can be profitably studied by FXR often can also be studied by FXD to permit a complete materials characterization

  7. X-Ray Polarimetry with GEMS

    Science.gov (United States)

    Strohmayer, Tod

    2011-01-01

    The polarization properties of cosmic X-ray sources are still largely unexplored. The Gravity and Extreme Magnetism SMEX (GEMS) will carry out the first sensitive X-ray polarization survey of a wide range of sources including; accreting compact objects (black holes and neutron stars), AGN, supernova remnants, magnetars and rotation-powered pulsars. GEMS employs grazing-incidence foil mirrors and novel time-projection chamber (TPC) polarimeters leveraging the photoelectric effect to achieve high polarization sensitivity in the 2 - 10 keV band. I will provide an update of the project status, illustrate the expected performance with several science examples, and provide a brief overview of the data analysis challenges

  8. CRL X-ray tube

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  9. CRL X-RAY TUBE

    OpenAIRE

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

    2015-01-01

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

  10. X rays and condensed matter

    International Nuclear Information System (INIS)

    Daillant, J.

    1997-01-01

    After a historical review of the discovery and study of X rays, the various interaction processes between X rays and matter are described: Thomson scattering, Compton scattering, X-photon absorption through photoelectric effect, and magnetic scattering. X ray sources such as the European Synchrotron Radiation Facility (ESRF) are described. The various X-ray applications are presented: imagery such as X tomography, X microscopy, phase contrast; X-ray photoelectron spectroscopy and X-ray absorption spectroscopy; X-ray scattering and diffraction techniques

  11. X-ray beam generator

    International Nuclear Information System (INIS)

    Koller, T.J.; Randmer, J.A.

    1977-01-01

    A method of minimizing the preferential angular absorption of the divergent beam from an X-ray generator is described. The generator consists of an X-ray shielded housing with an X-ray transmissive window symmetrically placed in radial alignment with a focal spot area on a sloped target surface of an X-ray tube in the housing. The X-ray tube may be of the stationary anode type or of the rotating anode type. (U.K.)

  12. Chest X-Ray

    Medline Plus

    Full Text Available ... Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us ... to consider the likelihood of benefit to your health. While a chest x-ray use a tiny ...

  13. Extended hard-X-ray emission in the inner few parsecs of the Galaxy

    DEFF Research Database (Denmark)

    Perez, Kerstin; Hailey, Charles J.; Bauer, Franz E.

    2015-01-01

    of objects emitting soft X-rays (less than 10 kiloelectronvolts) within the surrounding hundreds of parsecs, as well as the population responsible for unresolved X-ray emission extending along the Galactic plane, is dominated by accreting white dwarf systems. Observations of diffuse hard-X-ray (more than 10...... range. This emission is more sharply peaked towards the Galactic Centre than is the surface brightness of the soft-X-ray population. This could indicate a significantly more massive population of accreting white dwarfs, large populations of low-mass X-ray binaries or millisecond pulsars, or particle...

  14. Synchrotron x-ray sources and new opportunities in the soil and environmental sciences

    Energy Technology Data Exchange (ETDEWEB)

    Schulze, D. (Purdue Univ., Lafayette, IN (USA)); Anderson, S. (Michigan State Univ., East Lansing, MI (USA)); Mattigod, S. (Pacific Northwest Lab., Richland, WA (USA))

    1990-07-01

    This report contains the following papers: characteristics of the advanced photon source and comparison with existing synchrotron facilities; x-ray absorption spectroscopy: EXAFS and XANES -- A versatile tool to study the atomic and electronic structure of materials; applications of x-ray spectroscopy and anomalous scattering experiments in the soil and environmental sciences; X-ray fluorescence microprobe and microtomography.

  15. Synchrotron x-ray sources and new opportunities in the soil and environmental sciences

    International Nuclear Information System (INIS)

    Schulze, D.; Anderson, S.; Mattigod, S.

    1990-07-01

    This report contains the following papers: characteristics of the advanced photon source and comparison with existing synchrotron facilities; x-ray absorption spectroscopy: EXAFS and XANES -- A versatile tool to study the atomic and electronic structure of materials; applications of x-ray spectroscopy and anomalous scattering experiments in the soil and environmental sciences; X-ray fluorescence microprobe and microtomography

  16. SWIFT J1749.4-2807 : X-ray decay, refined position and optical observation

    NARCIS (Netherlands)

    Yang, Y.J.; Russell, D. M.; Wijnands, R.; van der Klis, M.; Altamirano, D.; Patruno, A.; Watts, A.; Armas Padilla, M.; Cavecchi, Y.; Degenaar, N.; Kalamkar, M.; Kaur, R.; Linares, M.; Casella, P.; Rea, N.; Soleri, P.; Lewis, F.; Kong, A. K. H.

    We analyzed seven, target ID 31686, Swift follow-up observations of the neutron-star X-ray transient Swfit J1749.4-2807 (Wijnands et al. 2009) currently in outburst and which was found to be an accreting millisecond X-ray pulsar (ATel #2565). The observations span from April 11 to April 20.

  17. Hard X-ray brightening of Ginga 1843+009 seen by INTEGRAL

    DEFF Research Database (Denmark)

    Leyder, J.-C.; Chenevez, Jérôme; Fiocchi, M.T.

    2005-01-01

    The transient X-ray pulsar, Ginga 1843+009, appears to be undergoing a hard X-ray outburst brighter than the one reported in May 2003 (ATEL #159). The source has been observed during ISWT observations of the Scutum Arm region with INTEGRAL and was first detected when the source was in the field o...

  18. X Persei - correlation between H-alpha and X-ray variability

    Science.gov (United States)

    Zamanov, R.; Stoyanov, K. A.; Petrov, N.; Nikolov, Y.; Marchev, D.; Wolter, U.

    2018-03-01

    We performed H-alpha spectroscopic observations of the Be/X-ray binary X Per, optical counterpart of the slow X-ray pulsar 4U 0352+30, using the 2.0m telescope of the Rozhen National Astronomical Observatory, Bulgaria and the 1.2m TIGRE telescope located in Mexico.

  19. X-ray filter for x-ray powder diffraction

    Science.gov (United States)

    Sinsheimer, John Jay; Conley, Raymond P.; Bouet, Nathalie C. D.; Dooryhee, Eric; Ghose, Sanjit

    2018-01-23

    Technologies are described for apparatus, methods and systems effective for filtering. The filters may comprise a first plate. The first plate may include an x-ray absorbing material and walls defining first slits. The first slits may include arc shaped openings through the first plate. The walls of the first plate may be configured to absorb at least some of first x-rays when the first x-rays are incident on the x-ray absorbing material, and to output second x-rays. The filters may comprise a second plate spaced from the first plate. The second plate may include the x-ray absorbing material and walls defining second slits. The second slits may include arc shaped openings through the second plate. The walls of the second plate may be configured to absorb at least some of second x-rays and to output third x-rays.

  20. X-ray refractometer

    International Nuclear Information System (INIS)

    Tur'yanskij, A.G.; Pirshin, I.V.

    2001-01-01

    Paper introduces a new circuit of X-ray refractometer to study angular and spectral features of refracted radiation within hard X-ray range. Refractometer incorporates two goniometers, two crystal-analyzers and three radiation detectors. The maximum distance between radiation source focal point and a receiving slit of the second goniometer is equal to 1.4 m. For the first time one obtained refraction patterns of fine-film specimens including C/Si stressed structure. Paper describes a new technique of refractometry via specimen oscillation at fixed position of a detecting device. Paper presents the measurement results of oscillation refraction patterns for specimens of melted quartz and ZnSe single crystal [ru

  1. X-ray microtomography

    International Nuclear Information System (INIS)

    Dunsmuir, J.H.; Ferguson, S.R.; D'Amico, K.L.; Stokes, J.P.

    1991-01-01

    In this paper the authors describe the application of a new high-resolution X-ray tomographic microscope to the study of porous media. The microscope was designed to exploit the properties of a synchrotron X-ray source to perform three dimensional tomography on millimeter sized objects with micron resolution and has been used in materials science studies with both synchrotron and conventional and synchrotron sources will be compared. In this work the authors have applied the microscope to measure the three dimensional structure of fused bead packs and berea sandstones with micron resolution and have performed preliminary studies of flow in these media with the microscope operated in a digital subtraction radiography mode. Computer graphics techniques have been applied to the data to visually display the structure of the pore body system. Tomographic imaging after flow experiments should detect the structure of the oil-water interface in the pore network and this work is ongoing

  2. X-ray Ordinance

    International Nuclear Information System (INIS)

    Kramer, R.; Zerlett, G.

    1983-01-01

    This commentary, presented as volume 2 of the Deutsches Strahlenschutzrecht (German legislation on radiation protection) deals with the legal provisions of the ordinance on the protection against harmful effects of X-radiation (X-ray Ordinance - RoeV), of March 1, 1973 (announced in BGBl.I, page 173), as amended by the ordinance on the protection against harmful effects of ionizing radiation, of October 13, 1976 (announced in BGBl. I, page 2905). Thus volume 2 completes the task started with volume 1, namely to present a comprehensive view and account of the body of laws governing radiation protection, a task which was thought useful as developments in the FRG led to regulations being split up into the X-ray Ordinance, and the Radiation Protection Ordinance. In order to present a well-balanced commentary on the X-ray Ordinance, it was necessary to discuss the provisions both from the legal and the medical point of view. This edition takes into account the Fourth Public Notice of the BMA (Fed. Min. of Labour and Social Affairs) concerning the implementation of the X-ray Ordinance of January 4, 1982, as well as court decisions and literature published in this field, until September 1982. In addition, the judgment of the Federal Constitutional Court, dated October 19, 1982, concerning the voidness of the law on government liability, and two decisions by the Federal High Court, dated November 23, 1982, concerning the right to have insight into medical reports - of great significance in practice - have been considered. This commentary therefore is up to date with current developments. (orig.) [de

  3. X-ray diffraction

    International Nuclear Information System (INIS)

    Einstein, J.R.; Wei, C.H.

    1982-01-01

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

  4. X-ray apparatus

    International Nuclear Information System (INIS)

    Tomita, Chuji.

    1980-01-01

    A principal object of the present invention is to provide an X-ray apparatus which is such that the distance between the surface of the patient's table and the floor on which the apparatus is installed is sufficiently small in the horizontal position of the patient's table of the roentgenographical pedestal and that the rotation of the pedestal from the horizontal position to a tilted position and further to the vertical position of the table can be carried out smoothly. (auth)

  5. Producing x-rays

    International Nuclear Information System (INIS)

    Mallozzi, P.J.; Epstein, H.M.; Jung, R.G.; Applebaum, D.C.; Fairand, B.P.; Gallagher, W.J.

    1977-01-01

    A method of producing x-rays by directing radiant energy from a laser onto a target is described. Conversion efficiency of at least about 3 percent is obtained by providing the radiant energy in a low-power precursor pulse of approximately uniform effective intensity focused onto the surface of the target for about 1 to 30 nanoseconds so as to generate an expanding unconfined coronal plasma having less than normal solid density throughout and comprising a low-density (underdense) region wherein the plasma frequency is less than the laser radiation frequency and a higher-density (overdense) region wherein the plasma frequency is greater than the laser radiation frequency and, about 1 to 30 nanoseconds after the precursor pulse strikes the target, a higher-power main pulse focused onto the plasma for about 10 -3 to 30 nanoseconds and having such power density and total energy that the radiant energy is absorbed in the underdense region and conducted into the overdense region to heat it and thus to produce x-rays therefrom with the plasma remaining substantially below normal solid density and thus facilitating the substantial emission of x-rays in the form of spectral lines arising from nonequilibrium ionization states

  6. The Water Recovery X-ray Rocket (WRX-R)

    Science.gov (United States)

    Miles, Drew

    2017-08-01

    The Water Recovery X-ray Rocket (WRX-R) is a diffuse soft X-ray spectrometer that will launch on a sounding rocket from the Kwajalein Atoll. WRX-R has a field of view of >10 deg2 and will observe the Vela supernova remnant. A mechanical collimator, state-of-the-art off-plane reflection grating array and hybrid CMOS detector will allow WRX to achieve the most highly-resolved spectrum of the Vela SNR ever recorded. In addition, this payload will fly a hard X-ray telescope that is offset from the soft X-ray spectrometer in order to observe the pulsar at the center of the remnant. We present here an introduction to the instrument, the expected science return, and an update on the state of the payload as we work towards launch.

  7. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... current x-ray images for diagnosis and disease management. top of page How is the procedure performed? ... position possible that still ensures x-ray image quality. top of page Who interprets the results and ...

  8. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... tissue shows up in shades of gray and air appears black. Until recently, x-ray images were ... position possible that still ensures x-ray image quality. top of page Who interprets the results and ...

  9. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... Videos About Us News Physician Resources Professions Site Index A-Z X-ray (Radiography) - Bone Bone x- ... x-ray machine is a compact apparatus that can be taken to the patient in a hospital ...

  10. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... shades of gray and air appears black. Until recently, x-ray images were maintained on large film ... assist you in finding the most comfortable position possible that still ensures x-ray image quality. top ...

  11. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... position possible that still ensures x-ray image quality. top of page Who interprets the results and ... ray examination. X-rays usually have no side effects in the typical diagnostic range for this exam. ...

  12. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... the body. X-rays are the oldest and most frequently used form of medical imaging. A bone ... bones. top of page How should I prepare? Most bone x-rays require no special preparation. You ...

  13. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... can be taken to the patient in a hospital bed or the emergency room. The x-ray ... position possible that still ensures x-ray image quality. top of page Who interprets the results and ...

  14. Bone X-Ray (Radiography)

    Medline Plus

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

  15. X-ray detector array

    International Nuclear Information System (INIS)

    Houston, J.M.

    1980-01-01

    The object of the invention (an ionization chamber X-ray detector array for use with high speed computerised tomographic imaging apparatus) is to reduce the time required to produce a tomographic image. The detector array described determines the distribution of X-ray intensities in one or more flat, coplanar X-ray beams. It comprises three flat anode sheets parallel to the X-ray beam, a plurality of rod-like cathodes between the anodes, a detector gas between the electrodes and a means for applying a potential between the electrodes. Each of the X-ray sources is collimated to give a narrow, planar section of X-ray photons. Sets of X-ray sources in the array are pulsed simultaneously to obtain X-ray transmission data for tomographic image reconstruction. (U.K.)

  16. Bone X-Ray (Radiography)

    Medline Plus

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

  17. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... patient. top of page How does the procedure work? X-rays are a form of radiation like ... Safety page for more information about radiation dose. Women should always inform their physician or x-ray ...

  18. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... image on photographic film or a special detector. Different parts of the body absorb the x-rays ... process is repeated. Two or three images (from different angles) will typically be taken. An x-ray ...

  19. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... standards used by radiology professionals. Modern x-ray systems have very controlled x-ray beams and dose control methods to minimize stray (scatter) radiation. This ensures ...

  20. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... up in shades of gray and air appears black. Until recently, x-ray images were maintained on ... Safety page for more information about radiation dose. Women should always inform their physician or x-ray ...

  1. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... tissues around or in bones. top of page How should I prepare? Most bone x-rays require ... is placed beneath the patient. top of page How does the procedure work? X-rays are a ...

  2. Bone X-Ray (Radiography)

    Medline Plus

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

  3. Soft X-ray Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Seely, John

    1999-05-20

    The contents of this report cover the following: (1) design of the soft x-ray telescope; (2) fabrication and characterization of the soft x-ray telescope; and (3) experimental implementation at the OMEGA laser facility.

  4. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... that might interfere with the x-ray images. Women should always inform their physician and x-ray technologist if there is any possibility that they are pregnant. Many imaging tests are not performed during pregnancy ...

  5. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... of page What are some common uses of the procedure? A bone x-ray is used to: ... and x-rays. top of page What does the equipment look like? The equipment typically used for ...

  6. The Imaging X-Ray Polarimetry Explorer (IXPE): Overview

    Science.gov (United States)

    O'Dell, Steve; Weisskopf, M.; Soffitta, P.; Baldini, L.; Bellazzini, R.; Costa, E.; Elsner, R.; Kaspi, V.; Kolodziejczak, J.; Latronico, L.; hide

    2017-01-01

    Mission background: Imaging x-ray polarimetry in 2–8 kiloelectronvolt band; NASA Astrophysics Small Explorer (SMEX) selected in 2017 January. Orbit: Pegasus-XL (airborne) launch in 2021, from Kwajalein; Equatorial circular orbit at greater than or approximately equal to 540 kilometers (620 kilometers, goal) altitude. Flight system: Spacecraft, payload structure, and integration by Ball Aerospace - Deployable payload boom from Orbital-ATK, under contract to Ball; X-ray Mirror Module Assemblies by NASA/MSFC; X-ray (polarization-sensitive) Instruments by IAPS/INAF (Istituto di Astrofisica e Planetologia Spaziali / Istituto Nazionale di Astrofisica) and INFN (Istituto Nazionale di Fisica Nucleare). Ground system: ASI (Agenzia Spaziale Italiana) Malindi ground station, with Singapore backup; Mission Operations Center at LASP (Laboratory for Atmospheric and Space Physics, University of Colorado); Science Operations Center at NASA/MSFC; Data archive at HEASARC (High Energy Astrophysics Science Archive Research Center), (NASA/GSFC), mirror at ASI Data Center. Science: Active galactic nuclei; Microquasars; Radio pulsars and pulsar wind nebulae; Supernova remnants; Magnetars; Accreting x-ray pulsars.

  7. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... used for bone x-rays consists of an x-ray tube suspended over a table on which the patient ... a hospital bed or the emergency room. The x-ray tube is connected to a flexible arm that is ...

  8. X-ray Crystallography Facility

    Science.gov (United States)

    2000-01-01

    Edward Snell, a National Research Council research fellow at NASA's Marshall Space Flight Center (MSFC), prepares a protein crystal for analysis by x-ray crystallography as part of NASA's structural biology program. The small, individual crystals are bombarded with x-rays to produce diffraction patterns, a map of the intensity of the x-rays as they reflect through the crystal.

  9. Bone X-Ray (Radiography)

    Medline Plus

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

  10. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... X-rays are a form of radiation like light or radio waves. X-rays pass through most objects, including the body. Once it is carefully aimed at the part of the body being examined, an x-ray machine produces a small ...

  11. Tunable X-ray source

    Science.gov (United States)

    Boyce, James R [Williamsburg, VA

    2011-02-08

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

  12. X-Ray Exam: Ankle

    Science.gov (United States)

    ... for Educators Search English Español X-Ray Exam: Ankle KidsHealth / For Parents / X-Ray Exam: Ankle What's in this article? What It Is Why ... You Have Questions Print What It Is An ankle X-ray is a safe and painless test ...

  13. Coherent hard x-ray focusing optics and applications

    Energy Technology Data Exchange (ETDEWEB)

    Yun, W.B.; Viccaro, P.J.; Chrzas, J.; Lai, B.

    1991-01-01

    Coherent hard x-ray beams with a flux exceeding 10{sup 9} photons/second with a bandwidth of 0.1% will be provided by the undulator at the third generation synchrotron radiation sources such as APS, ESRF, and Spring-8. The availability of such high flux coherent x-ray beams offers excellent opportunities for extending the coherence-based techniques developed in the visible and soft x-ray part of the electromagnetic spectrum to the hard x-rays. These x-ray techniques (e.g., diffraction limited microfocusing, holography, interferometry, phase contrast imaging and signal enhancement), may offer substantial advantages over non-coherence-based x-ray techniques currently used. For example, the signal enhancement technique may be used to enhance an anomalous x-ray or magnetic x-ray scattering signal by several orders of magnitude. Coherent x-rays can be focused to a very small (diffraction-limited) spot size, thus allowing high spatial resolution microprobes to be constructed. The paper will discuss the feasibility of the extension of some coherence-based techniques to the hard x-ray range and the significant progress that has been made in the development of diffraction-limited focusing optics. Specific experimental results for a transmission Fresnel phase zone plate that can focus 8.2 keV x-rays to a spot size of about 2 microns will be briefly discussed. The comparison of measured focusing efficiency of the zone plate with that calculated will be made. Some specific applications of zone plates as coherent x-ray optics will be discussed. 17 refs., 4 figs.

  14. X-ray diffraction

    International Nuclear Information System (INIS)

    Vries, J.L. de.

    1976-01-01

    The seventh edition of Philips' Review of literature on X-ray diffraction begins with a list of conference proceedings on the subject, organised by the Philips' organisation at regular intervals in various European countries. This is followed by a list of bulletins. The bibliography is divided according to the equipment (cameras, diffractometers, monochromators) and its applications. The applications are subdivided into sections for high/low temperature and pressure, effects due to the equipment, small angle scattering and a part for stress, texture and phase analyses of metals and quantitative analysis of minerals

  15. Obstetric X-rays

    International Nuclear Information System (INIS)

    Mwachi, M.K.

    2006-01-01

    Radiography of the pelvis should never be taken to diagnose early pregnancy, because of potential hazards of radiation damage to the growing foetus. the only indication occurs in the last week of pregnancy (37 weeks). Obstetric X-ray will help you answer like confirmation of malposition,multiple pregnancies; fetal abnormalities e.g. hydrocephalus, foetal disposition. The choice of radiographic projection will help give foetal presentation, disposition as well as foetal maturity. The search pattern helps you determine maternal and spine deformity, foetal spine and head , foetal presentation and any other anomalies

  16. Miniature X-Ray Tubes

    Science.gov (United States)

    Bearman, Gregory H.

    1995-01-01

    Miniature x-ray tubes proposed for use in portable instruments used to analyze minerals. Electrons from field emitter (instead of thermionic emitter) accelerated to target to generate x-rays. Fabricated from silicon wafers, micromachined field emitters (MFEs) not subject to breakage or restrictions on lifetimes, and tolerate vacuums that filaments cannot. Miniature x-ray tubes very robust, immune to shock and vibration, and permanently sealed with getter for continued pumping. Combined with solid-state x-ray detectors for analysis of x-ray fluorescence.

  17. Soft x-ray lasers

    International Nuclear Information System (INIS)

    Matthews, D.L.; Rosen, M.D.

    1988-01-01

    One of the elusive dreams of laser physicists has been the development of an x-ray laser. After 25 years of waiting, the x-ray laser has at last entered the scientific scene, although those now in operation are still laboratory prototypes. They produce soft x rays down to about five nanometers. X-ray lasers retain the usual characteristics of their optical counterparts: a very tight beam, spatial and temporal coherence, and extreme brightness. Present x-ray lasers are nearly 100 times brighter that the next most powerful x-ray source in the world: the electron synchrotron. Although Lawrence Livermore National Laboratory (LLNL) is widely known for its hard-x-ray laser program which has potential applications in the Strategic Defense Initiative, the soft x-ray lasers have no direct military applications. These lasers, and the scientific tools that result from their development, may one day have a place in the design and diagnosis of both laser fusion and hard x-ray lasers. The soft x-ray lasers now in operation at the LLNL have shown great promise but are still in the primitive state. Once x-ray lasers become reliable, efficient, and economical, they will have several important applications. Chief among them might be the creation of holograms of microscopic biological structures too small to be investigated with visible light. 5 figs

  18. NuSTAR Hard X-Ray Survey of the Galactic Center Region. II. X-Ray Point Sources

    DEFF Research Database (Denmark)

    Hong, JaeSub; Mori, Kaya; Hailey, Charles J.

    2016-01-01

    We present the first survey results of hard X-ray point sources in the Galactic Center (GC) region by NuSTAR. We have discovered 70 hard (3-79 keV) X-ray point sources in a 0.6 deg2 region around Sgr A* with a total exposure of 1.7 Ms, and 7 sources in the Sgr B2 field with 300 ks. We identify...... persistent luminous X-ray binaries (XBs) and the likely run-away pulsar called the Cannonball. New source-detection significance maps reveal a cluster of hard (>10 keV) X-ray sources near the Sgr. A diffuse complex with no clear soft X-ray counterparts. The severe extinction observed in the Chandra spectra...... indicate that the X-ray spectra of the NuSTAR sources should have kT > 20 keV on average for a single temperature thermal plasma model or an average photon index of Gamma = 1.5-2 for a power-law model. These findings suggest that the GC X-ray source population may contain a larger fraction of XBs with high...

  19. X-ray tube

    International Nuclear Information System (INIS)

    Mayo, B.J.

    1980-01-01

    An x-ray tube in which the x-ray origin is scanned on a circle around the patient, comprises a ring-shaped anode, an electron beam travelling along a circular path being deflected onto the anode at the desired positions. The electron beam path may be in a plane parallel to the anode and perhaps at the same radius. It may be in the same plane as a transmission target/anode and at a greater radius. The anode should extend over at least 180 0 although it may extend to 360 0 . Electrostatic means may be provided to constrain the beam to the circular path and further electrostatic means deflect it to the anode of the beam and ensure it is focused at the point of incidence. Collimators provide a planar fan-shaped beam and the anode may be shaped to attenuate side lobes of the radiation. Electrode collects electrons not deflected. The focal regions may be adjacent or otherwise. Coils may provide periodic focusing to overcome space charge dispersion and dynamic adjustment of the focusing before deflection ensures focusing at target incidence. Focusing may be absent near the deflection region, and current in the coil section near the focal region should be zero. (author)

  20. X-ray table

    International Nuclear Information System (INIS)

    Craig, J.R.; Otto, G.W.

    1980-01-01

    An X-ray radiographic or fluoroscopic table is described which includes a film holder with a frame attached to a cable running over end pulleys for positioning the holder longitudinally as desired under the table top. The holder has a front opening to receive a cassette-supporting tray which can be slid out on tracks to change the cassette. A reed switch on the frame is opened by a permanent magnet on the tray only when the tray is half-way out. When the switch is closed, an electromagnet locks the pulley and the holder in place. The holder is thus automatically locked in place not only during exposure (tray in) but when the tray is out for changing the cassette. To re-position the holder, the operator pulls the tray half-out and, using the tray itself, pushes the holder along the table, the holder being counterbalanced by a weight. (author)

  1. X-ray equipment

    International Nuclear Information System (INIS)

    Redmayne, I.G.B.

    1988-01-01

    The patent concerns a warning and protection system for mobile x-ray equipment used for 'on site' radiography, so that workers in the vicinity of such a working unit can be alerted to its presence. The invention is a local repeater warning system which gives a preliminary warning that energisation of the tubehead is imminent, as well as a switch near the tubehead to abort or inhibit energisation. The latter switch allows personnel caught in the vicinity of the tubehead to prevent energisation. The preliminary warning may be flashing lamps or by a klaxon. The control unit for the equipment may include a monitoring circuit to detect failure of the warning light or klaxon. (U.K.)

  2. X-ray equipment

    Energy Technology Data Exchange (ETDEWEB)

    Redmayne, I.G.B.

    1988-01-06

    The patent concerns a warning and protection system for mobile x-ray equipment used for 'on site' radiography, so that workers in the vicinity of such a working unit can be alerted to its presence. The invention is a local repeater warning system which gives a preliminary warning that energisation of the tubehead is imminent, as well as a switch near the tubehead to abort or inhibit energisation. The latter switch allows personnel caught in the vicinity of the tubehead to prevent energisation. The preliminary warning may be flashing lamps or by a klaxon. The control unit for the equipment may include a monitoring circuit to detect failure of the warning light or klaxon. (U.K.).

  3. X-ray instrumentation in astronomy

    International Nuclear Information System (INIS)

    Cuhlane, J.L.

    1985-01-01

    This book presents the proceedings of a conference devoted to x-ray instrumentation in astronomy. Special sections are: AXAF X-Ray Optical Systems; Specialized X-Ray Systems; X-Ray Optical Systems I; X-Ray Optical Systems II; Gas Filled X-Ray Detectors II; The NASA Advanced X-Ray Astrophysics Facility; X-Ray and EUV Spectrometers; Microchannel Plates; and Solid State Detectors

  4. X-Ray Lasers 2016

    CERN Document Server

    Bulanov, Sergei; Daido, Hiroyuki; Kato, Yoshiaki

    2018-01-01

    These proceedings comprise a selection of invited and contributed papers presented at the 15th International Conference on X-Ray Lasers (ICXRL 2016), held at the Nara Kasugano International Forum, Japan, from May 22 to 27, 2016. This conference was part of an ongoing series dedicated to recent developments in the science and technology of x-ray lasers and other coherent x-ray sources with additional focus on supporting technologies, instrumentation and applications.   The book showcases recent advances in the generation of intense, coherent x-rays, the development of practical devices and their applications across a wide variety of fields. It also discusses emerging topics such as plasma-based x-ray lasers, 4th generation accelerator-based sources and higher harmonic generations, as well as other x-ray generation schemes.

  5. Topological X-Rays Revisited

    Science.gov (United States)

    Lynch, Mark

    2012-01-01

    We continue our study of topological X-rays begun in Lynch ["Topological X-rays and MRI's," iJMEST 33(3) (2002), pp. 389-392]. We modify our definition of a topological magnetic resonance imaging and give an affirmative answer to the question posed there: Can we identify a closed set in a box by defining X-rays to probe the interior and without…

  6. X-ray filtration apparatus

    International Nuclear Information System (INIS)

    Thompson, G.

    1992-01-01

    This invention relates to an X-ray shielding support device. In spite of considerable development in X-ray taking techniques, a need still exists for effective shielding, inter alia, to compensate for variations in the thickness, density and the absorption properties of the object being studied. By appropriate shielding, the X-ray image produced is of sufficient detail, contrast and intensity over its entire area to constitute a useful diagnostic aid. It is also desirable to subject the patient to the smallest possible X-ray dosage. 4 figs

  7. X-ray Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yano, Junko; Yachandra, Vittal K.

    2009-07-09

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

  8. X-ray emission spectroscopy. X-ray fluorescence

    International Nuclear Information System (INIS)

    Despujols, J.

    1992-01-01

    Principles of X-ray emission spectrometry are first recalled, then wave-length dispersive and energy dispersive X-ray fluorescence spectrometer are described. They are essentially designed for qualitative and quantitative analysis of elements (Z>10). Sample preparation, calibration, corrections, interferences, accuracy are reviewed. Examples of use in different industries are given. (71 refs.)

  9. The Bursting Pulsar GRO J1744-28: the Slowest Transitional Pulsar?

    Science.gov (United States)

    Court, J. M. C.; Altamirano, D.; Sanna, A.

    2018-04-01

    GRO J1744-28 (the Bursting Pulsar) is a neutron star LMXB which shows highly structured X-ray variability near the end of its X-ray outbursts. In this letter we show that this variability is analogous to that seen in Transitional Millisecond Pulsars such as PSR J1023+0038: `missing link' systems consisting of a pulsar nearing the end of its recycling phase. As such, we show that the Bursting Pulsar may also be associated with this class of objects. We discuss the implications of this scenario; in particular, we discuss the fact that the Bursting Pulsar has a significantly higher spin period and magnetic field than any other known Transitional Pulsar. If the Bursting Pulsar is indeed transitional, then this source opens a new window of oppurtunity to test our understanding of these systems in an entirely unexplored physical regime.

  10. Testing pair production in pulsar magnetosphere

    Science.gov (United States)

    Timokhin, Andrey

    2017-09-01

    We propose to test whether electron-positron pair creation in the outer parts of pulsar magnetosphere, strongly preferred by the most recent pulsar models, can provide enough pair plasma to account for X-ray emission of pulsar wind nebulae. We will develop a theoretical foundation for such test and apply this test to several pulsars and their nebulae observed by Chandra. The proposed method is largely independent of the details of magnetosphere models and can be used as a powerful test for a broad range of pulsar models.

  11. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... a large photographic negative). Today, most images are digital files that are stored electronically. These stored images are easily accessible and are frequently compared to current x-ray images for diagnosis and ... the x-ray film holder or digital recording plate under the table in the area ...

  12. Chandra's X-ray Vision

    Indian Academy of Sciences (India)

    1999-07-23

    Jul 23, 1999 ... GENERAL I ARTICLE. Chandra's X-ray Vision. K P Singh. Chandra X-ray Observatory (CXO) is a scientific satellite (moon/ chandra), named after the Indian-born Nobel laureate. Subrahmanyan Chandrasekhar - one of the foremost astro- physicists of the twentieth century and popularly known as. Chandra.

  13. Traditional x-ray imaging

    International Nuclear Information System (INIS)

    Hay, G.A.

    1982-01-01

    Methods of imaging x-rays, with particular reference to medicine, are reviewed. The history and nature of x-rays, their production and spectra, contrast, shapes and fine structure, image transducers, including fluorescent screens, radiography, fluoroscopy, and image intensifiers, image detection, perception and enhancement and clinical applications are considered. (U.K.)

  14. X-ray based extensometry

    Science.gov (United States)

    Jordan, E. H.; Pease, D. M.

    1988-01-01

    A totally new method of extensometry using an X-ray beam was proposed. The intent of the method is to provide a non-contacting technique that is immune to problems associated with density variations in gaseous environments that plague optical methods. X-rays are virtually unrefractable even by solids. The new method utilizes X-ray induced X-ray fluorescence or X-ray induced optical fluorescence of targets that have melting temperatures of over 3000 F. Many different variations of the basic approaches are possible. In the year completed, preliminary experiments were completed which strongly suggest that the method is feasible. The X-ray induced optical fluorescence method appears to be limited to temperatures below roughly 1600 F because of the overwhelming thermal optical radiation. The X-ray induced X-ray fluorescence scheme appears feasible up to very high temperatures. In this system there will be an unknown tradeoff between frequency response, cost, and accuracy. The exact tradeoff can only be estimated. It appears that for thermomechanical tests with cycle times on the order of minutes a very reasonable system may be feasible. The intended applications involve very high temperatures in both materials testing and monitoring component testing. Gas turbine engines, rocket engines, and hypersonic vehicles (NASP) all involve measurement needs that could partially be met by the proposed technology.

  15. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... body. Once it is carefully aimed at the part of the body being examined, an x-ray machine produces a small burst of radiation that passes through the body, recording an image on photographic film or a special detector. Different parts of the body absorb the x-rays in ...

  16. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... standards used by radiology professionals. Modern x-ray systems have very controlled x-ray beams and dose control methods to minimize stray (scatter) radiation. This ensures that those parts of a patient's body not being imaged receive minimal radiation exposure. ...

  17. X-ray photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Attekum, P.M.T.M. van.

    1979-01-01

    The methods and results of X-ray photoelectron spectroscopy in the study of plasmons, alloys and gold compounds are discussed. After a comprehensive introduction, seven papers by the author, previously published elsewhere, are reprinted and these cover a wide range of the uses of X-ray photoelectron spectroscopy. (W.D.L.)

  18. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... current x-ray images for diagnosis and disease management. top of page How is the procedure performed? ... standards used by radiology professionals. Modern x-ray systems have very ... they provide little information about muscles, tendons or joints. An MRI may ...

  19. Dental X-ray apparatus

    International Nuclear Information System (INIS)

    Weiss, M.E.

    1980-01-01

    Intra-oral dental X-ray apparatus for panoramic radiography is described in detail. It comprises a tubular target carrier supporting at its distal end a target with an inclined forward face. Image definition is improved by positioning in the path of the X-rays a window of X-ray transmitting ceramic material, e.g. 90% oxide of Be, or Al, 7% Si0 2 . The target carrier forms a probe which can be positioned in the patient's mouth. X-rays are directed forwardly and laterally of the target to an X-ray film positioned externally. The probe is provided with a detachable sleeve having V-form arms of X-ray opaque material which serve to depress the tongue out of the radiation path and also shield the roof of the mouth and other regions of the head from the X-ray pattern. A cylindrical lead shield defines the X-ray beam angle. (author)

  20. X-ray imaging system

    International Nuclear Information System (INIS)

    Houston, J.M.

    1980-01-01

    A novel, high-speed apparatus for use in X-ray computerised tomography is described in detail. It consists of a semi-circular array of X-ray sources, collimators and an ion chamber array for detection of the X-rays. The X-ray sources may be pulsed in salvos such that the corresponding detectors in the array are only illuminated by one source. The use of computer controlled salvos speeds up the image processing by at least a factor of two. The ion chamber array is designed to have a constant detection efficiency for varying angles of X-ray incidence. A detailed description of the detector construction and suggested gaseous fillings are given. It is claimed that the present tomographic system allows fast and accurate imaging of internal body organs and is insensitive to the blurring effects which motion of these organs tends to produce. (UK)

  1. X-Ray Tomographic Reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Bonnie Schmittberger

    2010-08-25

    Tomographic scans have revolutionized imaging techniques used in medical and biological research by resolving individual sample slices instead of several superimposed images that are obtained from regular x-ray scans. X-Ray fluorescence computed tomography, a more specific tomography technique, bombards the sample with synchrotron x-rays and detects the fluorescent photons emitted from the sample. However, since x-rays are attenuated as they pass through the sample, tomographic scans often produce images with erroneous low densities in areas where the x-rays have already passed through most of the sample. To correct for this and correctly reconstruct the data in order to obtain the most accurate images, a program employing iterative methods based on the inverse Radon transform was written. Applying this reconstruction method to a tomographic image recovered some of the lost densities, providing a more accurate image from which element concentrations and internal structure can be determined.

  2. Observations of the Crab Nebula with the Chandra X-Ray Observatory

    Science.gov (United States)

    Weisskopf, Martin C.

    2012-01-01

    The Crab Nebula and its pulsar has been the subject of a number of detailed observations with the Chandra X-ray Observatory. The superb angular resolution of Chandra s high-resolution telescope has made possible numerous remarkable results. Here we describe a number of specific studies of the Crab that I and my colleagues have undertaken. We discuss the geometry of the system, which indicates that the "inner X-ray ring", typically identified with the termination shock of the pulsar s particle wind, is most likely not in the equatorial plane of the pulsar. Other topics are the northern wisps and their evolution with time; the characterization of features in the jet to the southeast; pulse-phase spectroscopy and possible correlations with the features at other wavelengths, particularly the optical polarization; and a search for correlations of the X-ray flux with the recently-discovered gamma -ray flares.

  3. Semiconductor X-ray detectors

    CERN Document Server

    Lowe, Barrie Glyn

    2014-01-01

    Identifying and measuring the elemental x-rays released when materials are examined with particles (electrons, protons, alpha particles, etc.) or photons (x-rays and gamma rays) is still considered to be the primary analytical technique for routine and non-destructive materials analysis. The Lithium Drifted Silicon (Si(Li)) X-Ray Detector, with its good resolution and peak to background, pioneered this type of analysis on electron microscopes, x-ray fluorescence instruments, and radioactive source- and accelerator-based excitation systems. Although rapid progress in Silicon Drift Detectors (SDDs), Charge Coupled Devices (CCDs), and Compound Semiconductor Detectors, including renewed interest in alternative materials such as CdZnTe and diamond, has made the Si(Li) X-Ray Detector nearly obsolete, the device serves as a useful benchmark and still is used in special instances where its large, sensitive depth is essential. Semiconductor X-Ray Detectors focuses on the history and development of Si(Li) X-Ray Detect...

  4. X-ray diffraction apparatus

    International Nuclear Information System (INIS)

    Padini, F.R.

    1978-01-01

    The invention provides an x-ray diffraction apparatus permitting the rotation of the divergence sit in conjunction with the rotation of the x-ray irradiated specimen, whereby the dimensions of the x-ray irradiated portion of the specimen remain substantially constant during the rotation of the specimen. In a preferred embodiment, the divergence slit is connected to a structural element linked with a second structural element connected to the specimen such that the divergence slit rotates at a lower angular speed than the specimen

  5. X-ray film calibration

    International Nuclear Information System (INIS)

    Stone, G.F.; Dittmore, C.H.; Henke, B.L.

    1986-01-01

    This paper discusses the use of silver halide x-ray films for imaging and spectroscopy which is limited by the range of intensities that can be recorded and densitometered. Using the manufacturers processing techniques can result in 10 2-3 range in intensity recorded over 0-5 density range. By modifying the chemistry and processing times, ranges of 10 5-6 can be recorded in the same density range. The authors report on x-ray film calibration work and dynamic range improvements. Changes to the processing chemistry and the resulting changes in dynamic range and x-ray sensitivity are discussed

  6. Upsurge of X-ray astronomy 230-

    International Nuclear Information System (INIS)

    Hudec, D.R.

    1978-01-01

    Instruments are described used for X-ray astronomy, namely X-ray detectors and X-ray telescopes. Unlike telescopes, the detectors do not comprise X-ray optics. A survey is given of the results obtained in solar and stellar X-ray astronomy and hypotheses are submitted on the origin of X radiation in the interstellar space. (J.B.)

  7. ACCURATE MODELING OF X-RAY EXTINCTION BY INTERSTELLAR GRAINS

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, John; Draine, B. T., E-mail: jah5@astro.princeton.edu, E-mail: draine@astro.princeton.edu [Princeton University Observatory, Peyton Hall, Princeton, NJ 08544-1001 (United States)

    2016-02-01

    Interstellar abundance determinations from fits to X-ray absorption edges often rely on the incorrect assumption that scattering is insignificant and can be ignored. We show instead that scattering contributes significantly to the attenuation of X-rays for realistic dust grain size distributions and substantially modifies the spectrum near absorption edges of elements present in grains. The dust attenuation modules used in major X-ray spectral fitting programs do not take this into account. We show that the consequences of neglecting scattering on the determination of interstellar elemental abundances are modest; however, scattering (along with uncertainties in the grain size distribution) must be taken into account when near-edge extinction fine structure is used to infer dust mineralogy. We advertise the benefits and accuracy of anomalous diffraction theory for both X-ray halo analysis and near edge absorption studies. We present an open source Fortran suite, General Geometry Anomalous Diffraction Theory (GGADT), that calculates X-ray absorption, scattering, and differential scattering cross sections for grains of arbitrary geometry and composition.

  8. ACCURATE MODELING OF X-RAY EXTINCTION BY INTERSTELLAR GRAINS

    International Nuclear Information System (INIS)

    Hoffman, John; Draine, B. T.

    2016-01-01

    Interstellar abundance determinations from fits to X-ray absorption edges often rely on the incorrect assumption that scattering is insignificant and can be ignored. We show instead that scattering contributes significantly to the attenuation of X-rays for realistic dust grain size distributions and substantially modifies the spectrum near absorption edges of elements present in grains. The dust attenuation modules used in major X-ray spectral fitting programs do not take this into account. We show that the consequences of neglecting scattering on the determination of interstellar elemental abundances are modest; however, scattering (along with uncertainties in the grain size distribution) must be taken into account when near-edge extinction fine structure is used to infer dust mineralogy. We advertise the benefits and accuracy of anomalous diffraction theory for both X-ray halo analysis and near edge absorption studies. We present an open source Fortran suite, General Geometry Anomalous Diffraction Theory (GGADT), that calculates X-ray absorption, scattering, and differential scattering cross sections for grains of arbitrary geometry and composition

  9. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... a large photographic negative). Today, most images are digital files that are stored electronically. These stored images ... and places the x-ray film holder or digital recording plate under the table in the area ...

  10. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... evaluation with additional views or a special imaging technique. A follow-up examination may also be necessary ... radiology protection organizations continually review and update the technique standards used by radiology professionals. Modern x-ray ...

  11. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... bone in the body, including the hand, wrist, arm, elbow, shoulder, spine, pelvis, hip, thigh, knee, leg ( ... x-ray tube is connected to a flexible arm that is extended over the patient while an ...

  12. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... to X-ray (Radiography) - Bone Sponsored by Please note RadiologyInfo.org is not a medical facility. Please ... is further reviewed by committees from the American College of Radiology (ACR) and the Radiological Society of ...

  13. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... to produce pictures of any bone in the body. It is commonly used to diagnose fractured bones ... x-rays involves exposing a part of the body to a small dose of ionizing radiation to ...

  14. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... top of page What are the benefits vs. risks? Benefits Bone x-rays are the fastest and ... in the typical diagnostic range for this exam. Risks There is always a slight chance of cancer ...

  15. Flash x-ray cinematography

    International Nuclear Information System (INIS)

    Stein, W.E.

    1976-01-01

    Experiments intended to provide an overview of the potential capabilities and limitations of flash x-ray cinematography as a diagnostic technique for a Fast Reactor Safety Test Facility are described. The results provide estimates of the x-ray pulse intensity required to obtain adequate radiographs of an array of fuel pins in a typical reactor configuration. An estimate of the upper limit on the pulse duration imposed by the reactor background radiation was also determined. X-ray cinematography has been demonstrated at a repetition rate limited only by the recording equipment on hand at the time of these measurements. These preliminary results indicate that flash x-ray cinematography of the motion of fuel in a Fast Reactor Test Facility is technically feasible

  16. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... fracture. guide orthopedic surgery, such as spine repair/fusion, joint replacement and fracture reductions. look for injury, ... CT Exams Arthritis X-ray, Interventional Radiology and Nuclear Medicine Radiation Safety How to Read Your Radiology ...

  17. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... knee, leg (shin), ankle or foot. top of page What are some common uses of the procedure? A ... information about pregnancy and x-rays. top of page What does the equipment look like? The equipment typically ...

  18. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... will analyze the images and send a signed report to your primary care or referring physician , who ... Medicine Radiation Safety How to Read Your Radiology Report Images related to X-ray (Radiography) - Bone Sponsored ...

  19. X-Ray Assembler Data

    Data.gov (United States)

    U.S. Department of Health & Human Services — Federal regulations require that an assembler who installs one or more certified components of a diagnostic x-ray system submit a report of assembly. This database...

  20. Dental X-ray apparatus

    International Nuclear Information System (INIS)

    Weiss, M.E.

    1980-01-01

    Intra-oral dental X-ray apparatus for panoramic dental radiography is described in detail. It comprises an electron gun having an elongated tubular target carrier extending into the patient's mouth. The carrier supports an inclined target for direction of an X-ray pattern towards a film positioned externally of the patient's mouth. Image definition is improved by a focusing anode which focuses the electron beam into a sharp spot (0.05 to 0.10 mm diameter) on the target. The potential on the focusing anode is adjustable to vary the size of the spot. An X-ray transmitting ceramic (oxides of Be, Al and Si) window is positioned adjacent to the front face of the target. The electron beam can be magnetically deflected to change the X-ray beam direction. (author)

  1. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... bear denotes child-specific content. Related Articles and Media Radiation Dose in X-Ray and CT Exams ... or your insurance provider to get a better understanding of the possible charges you will incur. Web ...

  2. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... pregnant. Many imaging tests are not performed during pregnancy so as not to expose the fetus to ... See the Safety page for more information about pregnancy and x-rays. top of page What does ...

  3. X-Rays - Multiple Languages

    Science.gov (United States)

    ... Expand Section Barium Swallow - 简体中文 (Chinese, Simplified (Mandarin dialect)) Bilingual PDF Health Information Translations Chest X-Ray - 简体中文 (Chinese, Simplified (Mandarin dialect)) ...

  4. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... x-ray uses a very small dose of ionizing radiation to produce pictures of any bone in the ... of the body to a small dose of ionizing radiation to produce pictures of the inside of the ...

  5. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... Leave jewelry at home and wear loose, comfortable clothing. You may be asked to wear a gown. ... appliances, eye glasses and any metal objects or clothing that might interfere with the x-ray images. ...

  6. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... abnormalities. This exam requires little to no special preparation. Tell your doctor and the technologist if there ... prepare? Most bone x-rays require no special preparation. You will be asked to remove some of ...

  7. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... in metabolic conditions. assist in the detection and diagnosis of bone cancer . locate foreign objects in soft ... frequently compared to current x-ray images for diagnosis and disease management. top of page How is ...

  8. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... the baby. See the Safety page for more information about pregnancy and x-rays. top of page ... procedure varies. See the Safety page for more information about radiation dose. Women should always inform their ...

  9. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... of page What will I experience during and after the procedure? A bone x-ray examination itself ... available in emergency rooms, physician offices, ambulatory care centers, nursing homes and other locations, making it convenient ...

  10. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... white on the x-ray, soft tissue shows up in shades of gray and air appears black. ... who will discuss the results with you. Follow-up examinations may be necessary. Your doctor will explain ...

  11. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... the patient in a hospital bed or the emergency room. The x-ray tube is connected to ... equipment is relatively inexpensive and widely available in emergency rooms, physician offices, ambulatory care centers, nursing homes ...

  12. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... patient. top of page How does the procedure work? X-rays are a form of radiation like ... taken of the unaffected limb, or of a child's growth plate (where new bone is forming), for ...

  13. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... small burst of radiation that passes through the body, recording an image on photographic film or a special detector. Different parts of the body absorb the x-rays in varying degrees. Dense ...

  14. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... procedure. You may experience discomfort from the cool temperature in the examination room. You may also find ... have very controlled x-ray beams and dose control methods to minimize stray (scatter) radiation. This ensures ...

  15. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... The teddy bear denotes child-specific content. Related Articles and Media Radiation Dose in X-Ray and ... facilities database . This website does not provide cost information. The costs for specific medical imaging tests, treatments ...

  16. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... limb, or of a child's growth plate (where new bone is forming), for comparison purposes. When the ... Exams Arthritis X-ray, Interventional Radiology and Nuclear Medicine Radiation Safety How to Read Your Radiology Report ...

  17. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... care is taken during x-ray examinations to use the lowest radiation dose possible while producing the best images for evaluation. National and international radiology protection organizations continually review ...

  18. X-ray screening materials

    International Nuclear Information System (INIS)

    Wardley, R.B.

    1981-01-01

    This invention relates to x-ray screening materials and especially to materials in sheet form for use in the production of, for example, protective clothing such as aprons and lower back shields, curtains, mobile screens and suspended shields. The invention is based on the observation that x-ray screening materials in sheet form having greater flexiblity than the hitherto known x-ray screening materials of the same x-ray absorber content can be produced if, instead of using a single sheet of filled sheet material of increased thickness, one uses a plurality of sheets of lesser thickness together forming a laminar material of the desired thickness and one bonds the individual sheets together at their edges and, optionally, at other spaced apart points away from the edges thereby allowing one sheet to move relative to another. (U.K.)

  19. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... ensures x-ray image quality. top of page Who interprets the results and how do I get ... report to your primary care or referring physician , who will discuss the results with you. Follow-up ...

  20. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... no special preparation. Tell your doctor and the technologist if there is any possibility you are pregnant. ... should always inform their physician and x-ray technologist if there is any possibility that they are ...

  1. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... is commonly used to diagnose fractured bones or joint dislocation. Bone x-rays are the fastest and ... to view and assess bone fractures, injuries and joint abnormalities. This exam requires little to no special ...

  2. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... the lowest radiation dose possible while producing the best images for evaluation. National and international radiology protection organizations continually review and update the technique standards used by radiology professionals. Modern x-ray ...

  3. Miniature x-ray source

    Science.gov (United States)

    Trebes, James E.; Bell, Perry M.; Robinson, Ronald B.

    2000-01-01

    A miniature x-ray source utilizing a hot filament cathode. The source has a millimeter scale size and is capable of producing broad spectrum x-ray emission over a wide range of x-ray energies. The miniature source consists of a compact vacuum tube assembly containing the hot filament cathode, an anode, a high voltage feedthru for delivering high voltage to the cathode, a getter for maintaining high vacuum, a connector for 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 fabricated from highly x-ray transparent materials, such as sapphire, diamond, or boron nitride.

  4. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... current x-ray images for diagnosis and disease management. top of page How is the procedure performed? ... examination may also be necessary so that any change in a known abnormality can be monitored over ...

  5. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... for more information about pregnancy and x-rays. A Word About Minimizing Radiation Exposure Special care is ... taking our brief survey: Survey Do you have a personal story about radiology? Share your patient story ...

  6. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... while the x-ray picture is taken to reduce the possibility of a blurred image. The technologist ... accredited facilities database . This website does not provide cost information. The costs for specific medical imaging tests, ...

  7. Duodenal X-ray diagnostics

    International Nuclear Information System (INIS)

    Scheppach, W.

    1982-01-01

    The publication provides an overview of duodenal X-ray diagnostics with the aid of barium meals in 1362 patients. The introducing paragraphs deal with the topographic anatomy of the region and the methodics of X-ray investigation. The chapter entitled ''processes at the duodenum itself'' describes mainly ulcers, diverticula, congenital anomalies, tumors and inflammations. The neighbourhood processes comprise in the first place diseases having their origin at the pancreas and bile ducts. As a conclusion, endoscopic rectograde cholangio-pancreaticography and percutaneous transhepatic cholangiography are pointed out as advanced X-ray investigation methods. In the annex of X-ray images some of the described phenomena are shown in exemplary manner. (orig./MG) [de

  8. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... replacement and fracture reductions. look for injury, infection, arthritis , abnormal bone growths and bony changes seen in ... injuries, including fractures, and joint abnormalities, such as arthritis. X-ray equipment is relatively inexpensive and widely ...

  9. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... the oldest and most frequently used form of medical imaging. A bone x-ray makes images of any ... a radiologist or other physician. To locate a medical imaging or radiation oncology provider in your community, you ...

  10. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... current x-ray images for diagnosis and disease management. top of page How is the procedure performed? ... radiation dose for this procedure varies. See the Safety page for more information about radiation dose. Women ...

  11. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... patient. top of page How does the procedure work? X-rays are a form of radiation like ... instead of ionizing radiation to create diagnostic images, has also been useful for injuries around joints, and ...

  12. Accelerator x-ray sources

    CERN Document Server

    Talman, Richard

    2007-01-01

    This first book to cover in-depth the generation of x-rays in particle accelerators focuses on electron beams produced by means of the novel Energy Recovery Linac (ERL) technology. The resulting highly brilliant x-rays are at the centre of this monograph, which continues where other books on the market stop. Written primarily for general, high energy and radiation physicists, the systematic treatment adopted by the work makes it equally suitable as an advanced textbook for young researchers.

  13. X-ray tube target

    International Nuclear Information System (INIS)

    Weber, R.G.

    1980-01-01

    A target with an improved heat emissive surface for use in a rotating anode type x-ray tube is described. The target consists of a body having a first surface portion made of x-ray emissive material and a second surface portion made of a heat emissive material comprising at least one of hafnium boride, hafnium oxide, hafnium nitride, hafnium silicide, and hafnium aluminide. (U.K.)

  14. X-ray data processing

    OpenAIRE

    Powell, Harold R.

    2017-01-01

    The method of molecular structure determination by X-ray crystallography is a little over a century old. The history is described briefly, along with developments in X-ray sources and detectors. The fundamental processes involved in measuring diffraction patterns on area detectors, i.e. autoindexing, refining crystal and detector parameters, integrating the reflections themselves and putting the resultant measurements on to a common scale are discussed, with particular reference to the most c...

  15. Observations of one young and three middle-aged γ-ray pulsars with the Gran Telescopio Canarias

    Science.gov (United States)

    Mignani, R. P.; Testa, V.; Rea, N.; Marelli, M.; Salvetti, D.; Torres, D. F.; De Oña Wilhelmi, E.

    2018-04-01

    We used the 10.4m Gran Telescopio Canarias to search for the optical counterparts to four isolated γ-ray pulsars, all detected in the X-rays by either XMM-Newton or Chandra but not yet in the optical. Three of them are middle-aged pulsars - PSR J1846+0919 (0.36 Myr), PSR J2055+2539 (1.2 Myr), PSR J2043+2740 (1.2 Myr) - and one, PSR J1907+0602, is a young pulsar (19.5 kyr). For both PSR J1907+0602 and PSR J2055+2539 we found one object close to the pulsar position. However, in both cases such an object cannot be a viable candidate counterpart to the pulsar. For PSR J1907+0602, because it would imply an anomalously red spectrum for the pulsar and for PSR J2055+2539 because the pulsar would be unrealistically bright (r' = 20.34 ± 0.04) for the assumed distance and interstellar extinction. For PSR J1846+0919, we found no object sufficiently close to the expected position to claim a possible association, whereas for PSR J2043+2740 we confirm our previous findings that the object nearest to the pulsar position is an unrelated field star. We used our brightness limits (g' ≈ 27), the first obtained with a large-aperture telescope for both PSR J1846+0919 and PSR J2055+2539, to constrain the optical emission properties of these pulsars and investigate the presence of spectral turnovers at low energies in their multi-wavelength spectra.

  16. Center for X-Ray Optics, 1992

    International Nuclear Information System (INIS)

    1993-08-01

    This report discusses the following topics: Center for X-Ray Optics; Soft X-Ray Imaging wit Zone Plate Lenses; Biological X-Ray microscopy; Extreme Ultraviolet Lithography for Nanoelectronic Pattern Transfer; Multilayer Reflective Optics; EUV/Soft X-ray Reflectometer; Photoemission Microscopy with Reflective Optics; Spectroscopy with Soft X-Rays; Hard X-Ray Microprobe; Coronary Angiography; and Atomic Scattering Factors

  17. Astronomical imaging with the X-ray observatory Hitomi

    Science.gov (United States)

    Nakajima, Hiroshi; Hitomi Collaboration

    2017-11-01

    We report an imaging capability of the Japan-led X-ray observatory Hitomi, formerly known as ASTRO-H. It carries four scientific instruments of Soft X-ray Imager (SXI: CCD camera), Hard X-ray Imager (HXI), Soft X-ray Spectrometer, and Soft Gamma-ray Detector, allowing us to perform a wide-band high-sensitive imaging spectroscopy. We highlight the specification and the performance we obtained with primarily regard to X-ray and soft gamma-ray imaging. Primary imaging instrument SXI utilizes four large-area X-ray CCDs positioned at the focal plane of Soft X-ray Telescope (SXT-I). Imaging area with a size of 62 mm square makes a largest field of view (FoV) of 38‧ square among the focal plane X-ray detectors, which enables us to observe extended objects such as clusters of galaxies and galactic supernova remnants with a single pointing in the soft X-ray band from 0.4 to 12 keV. HXI employs the hybrid sensors consisting of four layers of double-sided silicon strip detectors and a single layer of cadmium telluride double-sided strip detector covering the energy band from 5 to 80 keV. After the successful launch of Hitomi on February 17th, 2016 and the subsequent start up of all the instruments, imaging performance of both imagers are verified as expected from the ground calibration tests. The position of the active galactic nucleus of the central galaxy NGC1275 in the Perseus cluster is precisely seen by SXI, while the positional difference of line-of-sight velocity dispersion of the hot intracluster medium is measured inside by SXS. From the observation of Crab nebula, we obtain the on-pulse hard X-ray image with HXI as well as the time-averaged image in which the torus of the pulsar wind nebula can be seen.

  18. Study of the anomalous presence of iron in olive trees leaves by energy dispersion X-ray fluorescence; Estudo da presenca anomala de ferro em folhas de oliveiras por fluorescencia de raios-X por dispersao em energia

    Energy Technology Data Exchange (ETDEWEB)

    Aragao, P.H.A. [Universidade Estadual de Londrina, PR (Brazil). Dept. de Fisica; Cesareo, R. [Universita degli Studi di Sassari, Sardegna (Italy). Ist. di Matematica e Fisica; Melo, M.A.C. de; Paesano Junior, A. [Universidade Estadual de Maringa, PR (Brazil). Dept. de Fisica; Prota, U.; Fiori, M. [Universita degli Studi di Sassari, Sardegna (Italy). Faculta di Agraria; Marceddu, S. [Universita degli Studi di Sassari, Sardegna (Italy). Centro de Microscopia Eletronica

    2000-07-01

    In this work, we made use of the technique of X-ray fluorescence for dispersion in energy, to study a phytopathology denominated 'sooty mould' on leaves of Olive trees of Mediterranean area. The Olive trees are quite common and of great economical value in that area,especially in the island of Sardegna in Italy, where this work was developed, for treating one of the income main sources of the local economy. We observed a correlation between the elements Fe and Ca among infected leaves of Olive trees and not infected that is: leaves infected by the sooty mould present a large concentration of Fe and a low concentration of Ca when compared to the leaves not infected by the sooty mould. The oxidation state of Fe was determined by Moessbauer spectroscopy that revealed that this was Fe{sup 3+}. (author)

  19. Particle acceleration by pulsars

    International Nuclear Information System (INIS)

    Arons, Jonathan.

    1980-06-01

    The evidence that pulsars accelerate relativistic particles is reviewed, with emphasis on the γ-ray observations. The current state of knowledge of acceleration in strong waves is summarized, with emphasis on the inability of consistent theories to accelerate very high energy particles without converting too much energy into high energy photons. The state of viable models for pair creation by pulsars is summarized, with the conclusion that pulsars very likely lose rotational energy in winds instead of in superluminous strong waves. The relation of the pair creation models to γ-ray observations and to soft X-ray observations of pulsars is outlined, with the conclusion that energetically viable models may exist, but none have yet yielded useful agreement with the extant data. Some paths for overcoming present problems are discussed. The relation of the favored models to cosmic rays is discussed. It is pointed out that the pairs made by the models may have observable consequences for observation of positrons in the local cosmic ray flux and for observations of the 511 keV line from the interstellar medium. Another new point is that asymmetry of plasma supply from at least one of the models may qualitatively explain the gross asymmetry of the X-ray emission from the Crab nebula. It is also argued that acceleration of cosmic ray nuclei by pulsars, while energetically possible, can occur only at the boundary of the bubbles blown by the pulsars, if the cosmic ray composition is to be anything like that of the known source spectrum

  20. Ultrafast X-ray Sources

    International Nuclear Information System (INIS)

    Neil, George

    2010-01-01

    Since before the scattering of X-rays off of DNA led to the first understanding of the double helix structure, sources of X-rays have been an essential tool for scientists examining the structure and interactions of matter. The resolution of a microscope is proportional to the wavelength of light so x-rays can see much finer structures than visible light, down to single atoms. In addition, the energy of X-rays is resonant with the core atomic levels of atoms so with appropriate wavelengths the placement of specific atoms in a large molecule can be determined. Over 10,000 scientists use synchrotron sources, storage rings of high energy electrons, each year worldwide. As an example of such use, virtually every picture of a protein or drug molecule that one sees in the scientific press is a reconstruction based on X-ray scattering of synchrotron light from the crystallized form of that molecule. Unfortunately those pictures are static and proteins work through configuration (shape) changes in response to energy transfer. To understand how biological systems work requires following the energy flow to these molecules and tracking how shape changes drive their interaction with other molecules. We'd like to be able to freeze the action of these molecules at various steps along the way with an X-ray strobe light. How fast does it have to be? To actually get a picture of a molecule in a fixed configuration requires X-ray pulses as short as 30 femtoseconds (1/30 of a millionth of a millionth of a second). To capture the energy flow through changes in electronic levels requires a faster strobe, less than 1 femtosecond And to acquire such information in smaller samples with higher accuracy demands brighter and brighter X-rays. Unfortunately modern synchrotrons (dubbed 3rd Generation Light Sources) cannot deliver such short bright pulses of X-rays. An entirely new approach is required, linear-accelerator (linac-)-based light sources termed 4th or Next Generation Light Sources

  1. X-ray Echo Spectroscopy

    Science.gov (United States)

    Shvyd'ko, Yuri

    2016-02-01

    X-ray echo spectroscopy, a counterpart of neutron spin echo, is being introduced here to overcome limitations in spectral resolution and weak signals of the traditional inelastic x-ray scattering (IXS) probes. An image of a pointlike x-ray source is defocused by a dispersing system comprised of asymmetrically cut specially arranged Bragg diffracting crystals. The defocused image is refocused into a point (echo) in a time-reversal dispersing system. If the defocused beam is inelastically scattered from a sample, the echo signal acquires a spatial distribution, which is a map of the inelastic scattering spectrum. The spectral resolution of the echo spectroscopy does not rely on the monochromaticity of the x rays, ensuring strong signals along with a very high spectral resolution. Particular schemes of x-ray echo spectrometers for 0.1-0.02 meV ultrahigh-resolution IXS applications (resolving power >108 ) with broadband ≃5 - 13 meV dispersing systems are introduced featuring more than 103 signal enhancement. The technique is general, applicable in different photon frequency domains.

  2. The Ultracompact Nature of the Black Hole Candidate X-Ray Binary 47 Tuc X9

    Science.gov (United States)

    Bahramian, Arash; Heinke, Craig O.; Tudor, Vlad; Miller-Jones, James C. A.; Bogdanov, Slavko; Maccarone, Thomas J.; Knigge, Christian; Sivakoff, Gregory R.; Chomiuk, Laura; Strader, J.; hide

    2017-01-01

    47 Tuc X9 is a low-mass X-ray binary (LMXB) in the globular cluster 47 Tucanae, and was previously thought to be a cataclysmic variable. However, Miller-Jones et al. recently identified a radio counterpart to X9 (inferring a radio X-ray luminosity ratio consistent with black hole LMXBs), and suggested that the donor star might be a white dwarf. We report simultaneous observations of X9 performed by Chandra, NuSTAR and Australia Telescope Compact Array. We find a clear 28.18+/- 0.02-min periodic modulation in the Chandra data, which we identify as the orbital period, confirming this system as an ultracompact X-ray binary. Our X-ray spectral fitting provides evidence for photoionized gas having a high oxygen abundance in this system, which indicates a CO white dwarf donor. We also identify reflection features in the hard X-ray spectrum, making X9 the faintest LMXB to show X-ray reflection. We detect an approx. 6.8-d modulation in the X-ray brightness by a factor of 10, in archival Chandra, Swift and ROSAT data. The simultaneous radio X-ray flux ratio is consistent with either a black hole primary or a neutron star primary, if the neutron star is a transitional millisecond pulsar. Considering the measured orbital period (with other evidence of a white dwarf donor), and the lack of transitional millisecond pulsar features in the X-ray light curve, we suggest that this could be the first ultracompact black hole X-ray binary identified in our Galaxy.

  3. Imaging X-ray astronomy

    International Nuclear Information System (INIS)

    Elvis, M.

    1990-01-01

    The launch of the High Energy Astrophysical Observatory, more appealingly called the Einstein Observatory, marked one of the most revolutionary steps taken in astrophysics this century. Its greater sensitivity compared with earlier satellites and its ability to make high spacial and spectral resolution observations transformed X-ray astronomy. This book is based on a Symposium held in Cambridge, Massachusetts, to celebrate a decade of Einstein Observatory's achievements. It discusses the contributions that this satellite has made to each area of modern astrophysics and the diversity of the ongoing work based on Einstein data. There is a guide to each of the main data bases now coming on-line to increase the availability and to preserve this valuable archive for the future. A review of NASA's next big X-ray mission, AXAF, and a visionary program for novel X-ray astronomy satellites by Riccardo Giacconi conclude this wide-ranging volume. (author)

  4. Dental X-ray apparatus

    International Nuclear Information System (INIS)

    Weiss, M.E.

    1980-01-01

    Intra-oral X-ray apparatus which reduces the number of exposures necessary to obtain panoramic dental radiographs is described in detail. It comprises an electron gun, a tubular target carrier projecting from the gun along the beam axis and carrying at its distal end a target surrounded by a shield of X-ray opaque material. This shield extends forward and laterally of the target and has surfaces which define a wedge or cone-shaped radiation pattern delimited vertically by the root tips of the patient's teeth. A film holder is located externally of the patient's mouth. A disposable member can fit on the target carrier to depress the patient's tongue out of the radiation pattern and to further shield the roof of the mouth. The electron beam can be magnetically deflected to change the X-ray beam direction. (author)

  5. X-ray fluorescence holography.

    Science.gov (United States)

    Hayashi, Kouichi; Happo, Naohisa; Hosokawa, Shinya; Hu, Wen; Matsushita, Tomohiro

    2012-03-07

    X-ray fluorescence holography (XFH) is a method of atomic resolution holography which utilizes fluorescing atoms as a wave source or a monitor of the interference field within a crystal sample. It provides three-dimensional atomic images around a specified element and has a range of up to a few nm in real space. Because of this feature, XFH is expected to be used for medium-range local structural analysis, which cannot be performed by x-ray diffraction or x-ray absorption fine structure analysis. In this article, we explain the theory of XFH including solutions to the twin-image problem, an advanced measuring system, and data processing for the reconstruction of atomic images. Then, we briefly introduce our recent applications of this technique to the analysis of local lattice distortions in mixed crystals and nanometer-size clusters appearing in the low-temperature phase of a shape-memory alloy.

  6. X-ray fluorescence holography

    International Nuclear Information System (INIS)

    Hayashi, Kouichi; Happo, Naohisa; Hosokawa, Shinya; Hu Wen; Matsushita, Tomohiro

    2012-01-01

    X-ray fluorescence holography (XFH) is a method of atomic resolution holography which utilizes fluorescing atoms as a wave source or a monitor of the interference field within a crystal sample. It provides three-dimensional atomic images around a specified element and has a range of up to a few nm in real space. Because of this feature, XFH is expected to be used for medium-range local structural analysis, which cannot be performed by x-ray diffraction or x-ray absorption fine structure analysis. In this article, we explain the theory of XFH including solutions to the twin-image problem, an advanced measuring system, and data processing for the reconstruction of atomic images. Then, we briefly introduce our recent applications of this technique to the analysis of local lattice distortions in mixed crystals and nanometer-size clusters appearing in the low-temperature phase of a shape-memory alloy. (topical review)

  7. X-ray Emission from Solar Flares

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Solar flares; X-ray detectors; X-ray line emission and continuum; break energy; microflares. Abstract. Solar X-ray Spectrometer (SOXS), the first space-borne solar astronomy experiment of India was designed to improve our current understanding of X-ray emission from the Sun in general and solar flares in ...

  8. History of x-ray astronomy

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. History of x-ray astronomy. Major X-ray Missions. 1970 :UHURU: detected 339 new sources (1st sky coverage). 1978: Einstein First x-ray imaging mission (>1000 sources). 1990: ROSAT; Soft X-ray imaging mission; detected 100,000 sources (deeper sky coverage) ...

  9. X-Ray Exam: Cervical Spine

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español X-Ray Exam: Cervical Spine KidsHealth / For Parents / X-Ray ... MRI): Lumbar Spine Broken Bones Getting an X-ray (Video) X-Ray (Video) View more Partner Message About Us ...

  10. Chest X-Ray (Chest Radiography)

    Science.gov (United States)

    ... News Physician Resources Professions Site Index A-Z X-ray (Radiography) - Chest Chest x-ray uses a very ... limitations of Chest Radiography? What is a Chest X-ray (Chest Radiography)? The chest x-ray is the ...

  11. X-Ray Exam: Neck (For Parents)

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español X-Ray Exam: Neck KidsHealth / For Parents / X-Ray Exam: ... Neck Enlarged Adenoids Croup Sinusitis Getting an X-ray (Video) X-Ray (Video) View more Partner Message About Us ...

  12. Semiconductor X-ray spectrometers

    International Nuclear Information System (INIS)

    Muggleton, A.H.F.

    1978-02-01

    An outline is given of recent developments in particle and photon induced x-ray fluorescence (XRF) analysis. Following a brief description of the basic mechanism of semiconductor detector operation a comparison is made between semiconductor detectors, scintillators and gas filled proportional devices. Detector fabrication and cryostat design are described in more detail and the effects of various device parameters on system performance, such as energy resolution, count rate capability, efficiency, microphony, etc. are discussed. The main applications of these detectors in x-ray fluorescence analysis, electron microprobe analysis, medical and pollution studies are reviewed

  13. Portable X-Ray Device

    Science.gov (United States)

    1983-01-01

    Portable x-ray instrument developed by NASA now being produced commercially as an industrial tool may soon find further utility as a medical system. The instrument is Lixiscope - Low Intensity X-Ray Imaging Scope -- a self-contained, battery-powered fluoroscope that produces an instant image through use of a small amount of radioactive isotope. Originally developed by Goddard Space Flight Center, Lixiscope is now being produced by Lixi, Inc. which has an exclusive NASA license for one version of the device.

  14. Overutilization of x-rays

    International Nuclear Information System (INIS)

    Abrams, H.L.

    1979-01-01

    In this article on the overutilization of x-rays the author defines the term overutilization as excessive irradiation per unit of diagnostic information, therapeutic impact, or health outcome. Three main factors are described which lead to overutilization of x-rays: excessive radiation per film; excessive films per examination; and excessive examinations per patient. Topics discussed which influence the excessive examinations per patient are: the physician's lack of knowledge; undue dependence; lack of screening by radiologists; the physician's need for action and certainty; patient demand; reimbursement policies; institutional requirements; preventive medicine; defensive medicine; and the practice of radiology by nonradiologists

  15. X-ray data processing.

    Science.gov (United States)

    Powell, Harold R

    2017-10-31

    The method of molecular structure determination by X-ray crystallography is a little over a century old. The history is described briefly, along with developments in X-ray sources and detectors. The fundamental processes involved in measuring diffraction patterns on area detectors, i.e. autoindexing, refining crystal and detector parameters, integrating the reflections themselves and putting the resultant measurements on to a common scale are discussed, with particular reference to the most commonly used software in the field. © 2017 The Author(s).

  16. Tetrahedral hydrocarbon nanoparticles in space: X-ray spectra

    Science.gov (United States)

    Bilalbegović, G.; Maksimović, A.; Valencic, L. A.

    2018-03-01

    It has been proposed, or confirmed, that diamond nanoparticles exist in various environments in space: close to active galactic nuclei, in the vicinity of supernovae and pulsars, in the interior of several planets in the Solar system, in carbon planets and other exoplanets, carbon-rich stars, meteorites, in X-ray active Herbig Ae/Be stars, and in the interstellar medium. Using density functional theory methods we calculate the carbon K-edge X-ray absorption spectrum of two large tetrahedral nanodiamonds: C26H32 and C51H52. We also study and test our methods on the astrophysical molecule CH4, the smallest C-H tetrahedral structure. A possible detection of nanodiamonds from X-ray spectra by future telescopes, such as the project Arcus, is proposed. Simulated spectra of the diffuse interstellar medium using Cyg X-2 as a source show that nanodiamonds studied in this work can be detected by Arcus, a high resolution X-ray spectrometer mission selected by NASA for a Phase A concept study.

  17. X-ray microscopes at BESSY II

    International Nuclear Information System (INIS)

    Guttmann, P.; Niemann, B.; Thieme, J.; Wiesemann, U.; Rudolph, D.; Schmahl, G.

    2000-01-01

    The undulator U41 at BESSY II will be used as source for X-ray microscopes. An overview of the X-ray microscopy area is presented. After finishing the construction phase a transmission X-ray microscope, a scanning transmission X-ray microscope and an X-ray test chamber will be available. The transmission X-ray microscope will allow investigations with high lateral resolution at moderate energy resolution while the scanning transmission X-ray microscope will allow high energy resolution at moderate lateral resolution of the same specimen

  18. Illumination system for X-ray lithography

    International Nuclear Information System (INIS)

    Buckley, W.D.

    1989-01-01

    An X-ray lithography system is described, comprising: a point source of X-Ray radiation; a wafer plane disposed in spaced relation to the point source of X-Ray radiation; a mask disposed between the point source of X-Ray radiation and the wafer plane whereby X-Ray radiation from the point source of X-ray radiation passes through the mask to the water plane; and X-Ray absorbent means mounted between the point source of X-Ray radiation and the wafer plane, the X-Ray absorbent means being of quadratically absorption from maximum absorption at the center to minimum absorption at the edge so as to have a radial absorption gradient profile to compensate for radial flux variation of the X-Ray radiation

  19. A state change in the low-mass X-ray binary XSS J12270-4859

    Science.gov (United States)

    Bassa, C. G.; Patruno, A.; Hessels, J. W. T.; Keane, E. F.; Monard, B.; Mahony, E. K.; Bogdanov, S.; Corbel, S.; Edwards, P. G.; Archibald, A. M.; Janssen, G. H.; Stappers, B. W.; Tendulkar, S.

    2014-06-01

    Millisecond radio pulsars acquire their rapid rotation rates through mass and angular momentum transfer in a low-mass X-ray binary system. Recent studies of PSR J1824-2452I and PSR J1023+0038 have observationally demonstrated this link, and they have also shown that such systems can repeatedly transition back-and-forth between the radio millisecond pulsar and low-mass X-ray binary states. This also suggests that a fraction of such systems are not newly born radio millisecond pulsars but are rather suspended in a back-and-forth, state-switching phase, perhaps for gigayears. XSS J12270-4859 has been previously suggested to be a low-mass X-ray binary, and until recently the only such system to be seen at MeV-GeV energies. We present radio, optical and X-ray observations that offer compelling evidence that XSS J12270-4859 is a low-mass X-ray binary which transitioned to a radio millisecond pulsar state between 2012 November 14 and December 21. We use optical and X-ray photometry/spectroscopy to show that the system has undergone a sudden dimming and no longer shows evidence for an accretion disc. The optical observations constrain the orbital period to 6.913 ± 0.002 h.

  20. Radio and X-ray emission from newly born remnants

    International Nuclear Information System (INIS)

    Salvati, M.

    1983-01-01

    Radio and X-ray observations of SN 1979c and SN 1980k offer a unique opportunity of monitoring the transition from supernovae to remnants. By means of the two-frequency radio light curves, the hypothesis that these objects are surrounded by circumstellar matter, originated in a presupernova wind, is tested, and the relevant parameters are derived. Then the absorption-corrected light curves are used to test the various proposed models. SN 1980k appears to be powered by a canonical shock, while SN 1979c is a good plerion candidate. An optical pulsar could still be detected at its location. (Auth.)

  1. Listening in on Baby - Monitoring the Youngest Known Pulsar

    Science.gov (United States)

    Gotthelf, Eric

    We have discovered a most remarkable young pulsar, PSR J1846-0258, in the core of a Crab-like pulsar wind nebula at the center of the bright shell-type SNR Kes 75. Based on its spin-down rate and X-ray spectrum, PSR J1846-0258 is likely the youngest known rotation-powered pulsar. Compared to the Crab pulsar, however, its period, spin-down rate, and X-ray conversion efficiency are each an order of magnitude greater, likely the result of its extreme magnetic field, above the quantum critical threshold. We propose to continue our monitoring campaign of PSR~J1846-0258 to measure the braking index, characterize its timing noise, and search for evidence of timing glitches. Furthermore, an X- ray ephemeris contemporal with GLAST is critical to detecting the pulsar at higher energies.

  2. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... the table in the area of the body being imaged. When necessary, sandbags, pillows or other positioning devices will be used to help you ... have very controlled x-ray beams and dose control methods to minimize stray (scatter) ... imaged receive minimal radiation exposure. top of page ...

  3. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us News Physician Resources Professions Site Index A-Z X-ray (Radiography) - Bone ...

  4. X-ray tube transformer

    International Nuclear Information System (INIS)

    1980-01-01

    An X-ray generator is described which comprises a transmission line transformer including an electrical conductor with a cavity and a second electrical conductor including helical windings disposed along a longitudinal axis within the cavity of the first conductor. The windings have a pitch which varies per unit length along the axis. There is dielectric material in the cavity for insulation and to couple electromagnetically the two conductors in response to an electric current flowing through the conductors, which have an impedance between them; this varies with distance along the axis of the helix of the second conductor. An X-ray tube is disposed along the longitudinal axis within the cavity, for radiating X-rays. The invention increases the voltage of applied voltage pulses at the remote tube-head with a transformer formed by using a spiral delay line geometry to give a tapered-impedance coaxial high voltage multiplier for pulse voltage operation. This transformer is smaller and lighter than previous designs for the same high peak voltage and power ratings. This is important because the penetration capabilities of Flash X-ray equipment increase with voltage, particularly in heavy materials such as steel. (U.K.)

  5. X-ray fluorescence spectrometry

    International Nuclear Information System (INIS)

    Vries, J.L. de.

    1976-01-01

    The seventh edition of Philips' Review of Literature on x-ray fluorescence spectrometry starts with a list of conference proceedings on the subject, organised by the Philips organisation at regular intervals in various European countries. It is followed by a list of bulletins. The bibliography is subdivided according to spectra, equipment, applications and absorption analysis

  6. X-Ray Diffractive Optics

    Science.gov (United States)

    Dennis, Brian; Li, Mary; Skinner, Gerald

    2013-01-01

    X-ray optics were fabricated with the capability of imaging solar x-ray sources with better than 0.1 arcsecond angular resolution, over an order of magnitude finer than is currently possible. Such images would provide a new window into the little-understood energy release and particle acceleration regions in solar flares. They constitute one of the most promising ways to probe these regions in the solar atmosphere with the sensitivity and angular resolution needed to better understand the physical processes involved. A circular slit structure with widths as fine as 0.85 micron etched in a silicon wafer 8 microns thick forms a phase zone plate version of a Fresnel lens capable of focusing approx. =.6 keV x-rays. The focal length of the 3-cm diameter lenses is 100 microns, and the angular resolution capability is better than 0.1 arcsecond. Such phase zone plates were fabricated in Goddard fs Detector Development Lab. (DDL) and tested at the Goddard 600-microns x-ray test facility. The test data verified that the desired angular resolution and throughput efficiency were achieved.

  7. X-rays from stars

    Science.gov (United States)

    Güdel, Manuel

    2004-07-01

    Spectroscopic studies available from Chandra and XMM-Newton play a pivotal part in the understanding of the physical processes in stellar (magnetic and non-magnetic) atmospheres. It is now routinely possible to derive densities and to study the influence of ultraviolet radiation fields, both of which can be used to infer the geometry of the radiating sources. Line profiles provide important information on bulk mass motions and attenuation by neutral matter, e.g. in stellar winds. The increased sensitivity has revealed new types of X-ray sources in systems that were thought to be unlikely places for X-rays: flaring brown dwarfs, including rather old, non-accreting objects, and terminal shocks in jets of young stars are important examples. New clues concerning the role of stellar high-energy processes in the modification of the stellar environment (ionization, spallation, etc.) contribute significantly to our understanding of the "astro-ecology" in forming planetary systems. Technological limitations are evident. The spectral resolution has not reached the level where bulk mass motions in cool stars become easily measurable. Higher resolution would also be important to perform X-ray "Doppler imaging" in order to reconstruct the 3-D distribution of the X-ray sources around a rotating star. Higher sensitivity will be required to perform high-resolution spectroscopy of weak sources such as brown dwarfs or embedded pre-main-sequence sources. A new generation of satellites such as Constellation-X or XEUS should pursue these goals.

  8. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... small burst of radiation that passes through the body, recording an image on photographic film or a special detector. Different ... This ensures that those parts of a patient's body not being imaged receive minimal radiation ... x-ray images are among the clearest, most detailed views of ...

  9. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... small burst of radiation that passes through the body, recording an image on photographic film or a special detector. Different ... about radiology? Share your patient story here Images ... content. Related Articles and Media Radiation Dose in X-Ray and CT Exams ...

  10. High resolution X ray spectroscopy

    International Nuclear Information System (INIS)

    Bartiromo, R.

    1987-01-01

    This paper is devoted to a detailed discussion of the physical processes which are responsible for the emission spectra of H-like and He-like ion of high Z impurities in low density plasmas. The application of high resolution X-ray spectroscopy to the diagnostic of tokamak plasmas is also discussed and examples of the results obtained are presented

  11. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us News Physician ... An x-ray (radiograph) is a noninvasive medical test that helps physicians diagnose and treat medical conditions. ...

  12. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... the equipment look like? How does the procedure work? How is the procedure performed? What will I experience during and after the procedure? Who interprets the results and how do I get them? What are the benefits vs. risks? What are the limitations of Bone X-ray ( ...

  13. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... over time. top of page What are the benefits vs. risks? Benefits Bone x-rays are the fastest and easiest ... cancer from excessive exposure to radiation. However, the benefit of an accurate diagnosis far outweighs the risk. ...

  14. X-ray image coding

    International Nuclear Information System (INIS)

    1974-01-01

    The invention aims at decreasing the effect of stray radiation in X-ray images. This is achieved by putting a plate between source and object with parallel zones of alternating high and low absorption coefficients for X-radiation. The image is scanned with the help of electronic circuits which decode the signal space coded by the plate, thus removing the stray radiation

  15. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... any possibility that they are pregnant. Many imaging tests are not performed during pregnancy so as not to expose the fetus to ... See the Safety page for more information about pregnancy and x-rays. A Word About Minimizing ... imaging tests and treatments have special pediatric considerations. The teddy ...

  16. X-rays and magnetism

    International Nuclear Information System (INIS)

    Fischer, Peter; Ohldag, Hendrik

    2015-01-01

    Magnetism is among the most active and attractive areas in modern solid state physics because of intriguing phenomena interesting to fundamental research and a manifold of technological applications. State-of-the-art synthesis of advanced magnetic materials, e.g. in hybrid structures paves the way to new functionalities. To characterize modern magnetic materials and the associated magnetic phenomena, polarized x-rays have emerged as unique probes due to their specific interaction with magnetic materials. A large variety of spectroscopic and microscopic techniques have been developed to quantify in an element, valence and site-sensitive way properties of ferro-, ferri-, and antiferromagnetic systems, such as spin and orbital moments, and to image nanoscale spin textures and their dynamics with sub-ns time and almost 10 nm spatial resolution. The enormous intensity of x-rays and their degree of coherence at next generation x-ray facilities will open the fsec time window to magnetic studies addressing fundamental time scales in magnetism with nanometer spatial resolution. This review will give an introduction into contemporary topics of nanoscale magnetic materials and provide an overview of analytical spectroscopy and microscopy tools based on x-ray dichroism effects. Selected examples of current research will demonstrate the potential and future directions of these techniques. (report on progress)

  17. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... over time. top of page What are the benefits vs. risks? Benefits Bone x-rays are the fastest and easiest ... images for evaluation. National and international radiology protection organizations continually review and update the technique standards used ...

  18. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... time. Follow-up examinations are sometimes the best way to see if treatment is working or if a finding is stable or changed over time. top of page What are the benefits vs. risks? Benefits Bone x-rays are the fastest and easiest way for a ...

  19. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos ... to current x-ray images for diagnosis and disease management. top of page How is the procedure ...

  20. X-ray absorption holography

    Czech Academy of Sciences Publication Activity Database

    Kopecký, Miloš; Lausi, A.; Bussetto, E.; Kub, Jiří; Savoia, A.

    2002-01-01

    Roč. 88, č. 18 (2002), s. 185503-1 - 185503-3 ISSN 0031-9007 R&D Projects: GA MŠk LN00A100 Institutional research plan: CEZ:AV0Z1010921 Keywords : x-ray holography Subject RIV: BH - Optics, Masers, Lasers Impact factor: 7.323, year: 2002

  1. Compact x-ray source and panel

    Science.gov (United States)

    Sampayon, Stephen E [Manteca, CA

    2008-02-12

    A compact, self-contained x-ray source, and a compact x-ray source panel having a plurality of such x-ray sources arranged in a preferably broad-area pixelized array. Each x-ray source includes an electron source for producing an electron beam, an x-ray conversion target, and a multilayer insulator separating the electron source and the x-ray conversion target from each other. The multi-layer insulator preferably has a cylindrical configuration with a plurality of alternating insulator and conductor layers surrounding an acceleration channel leading from the electron source to the x-ray conversion target. A power source is connected to each x-ray source of the array to produce an accelerating gradient between the electron source and x-ray conversion target in any one or more of the x-ray sources independent of other x-ray sources in the array, so as to accelerate an electron beam towards the x-ray conversion target. The multilayer insulator enables relatively short separation distances between the electron source and the x-ray conversion target so that a thin panel is possible for compactness. This is due to the ability of the plurality of alternating insulator and conductor layers of the multilayer insulators to resist surface flashover when sufficiently high acceleration energies necessary for x-ray generation are supplied by the power source to the x-ray sources.

  2. Characterization of the Optical and X-ray Properties of the Northwestern Wisps in the Crab Nebula

    Science.gov (United States)

    Weisskopf, M. C.; Bucciantini, N.; Idec, W.; Nillson, K.; Schweizer, T.; Tennant, A. F.; Zanin, R.

    2013-01-01

    We have studied the wisps to the northwest of the Crab pulsar as part of a multi-wavelength campaign in the visible and in X-rays. Optical observations were obtained using the Nordic Optical Telescope in La Palma and X-ray observations were made with the Chandra X-ray Observatory. The observing campaign took place from October 2010 until September 2012. About once per year we observe wisps forming and peeling off from (or near) the region commonly associated with the termination shock of the pulsar wind. We find that the exact locations of the northwestern wisps in the optical and in X-rays are similar but not coincident, with X-ray wisps preferentially located closer to the pulsar. This suggests that the optical and X-ray wisps are not produced by the same particle distribution. It is also interesting to note that the optical and radio wisps are also separated from each other (Bietenholz et al. 2004). Our measurements and their implications are interpreted in terms of a Doppler-boosted ring model that has its origin in MHD modeling. While the Doppler boosting factors inferred from the X-ray wisps are consistent with current MHD simulations of PWNe, the optical boosting factors are not, and typically exceed values from MHD simulations by about a factor of 4.

  3. High-Resolution X-ray Emission and X-ray Absorption Spectroscopy

    NARCIS (Netherlands)

    Groot, F.M.F. de

    2000-01-01

    In this review, high-resolution X-ray emission and X-ray absorption spectroscopy will be discussed. The focus is on the 3d transition-metal systems. To understand high-resolution X-ray emission and reso-nant X-ray emission, it is first necessary to spend some time discussing the X-ray absorption

  4. Expanded potential of seleno-carbohydrates as a molecular tool for X-ray structural determination of a carbohydrate-protein complex with single/multi-wavelength anomalous dispersion phasing.

    Science.gov (United States)

    Suzuki, Tatsuya; Makyio, Hisayoshi; Ando, Hiromune; Komura, Naoko; Menjo, Masanori; Yamada, Yusuke; Imamura, Akihiro; Ishida, Hideharu; Wakatsuki, Soichi; Kato, Ryuichi; Kiso, Makoto

    2014-04-01

    Seleno-lactoses have been successfully synthesized as candidates for mimicking carbohydrate ligands for human galectin-9 N-terminal carbohydrate recognition domain (NCRD). Selenium was introduced into the mono- or di-saccharides using p-methylselenobenzoic anhydride (Tol2Se) as a novel selenating reagent. The TolSe-substituted monosaccharides were converted into selenoglycosyl donors or acceptors, which were reacted with coupling partners to afford seleno-lactoses. The seleno-lactoses were converted to the target compounds. The structure of human galectin-9 NCRD co-crystallized with 6-MeSe-lactose was determined with single/multi-wavelength anomalous dispersion (SAD/MAD) phasing and was similar to that of the co-crystal with natural lactose. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Gamma-Ray Pulsar Studies With GLAST

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, D.J.; /NASA, Goddard

    2011-11-23

    Some pulsars have their maximum observable energy output in the gamma-ray band, offering the possibility of using these high-energy photons as probes of the particle acceleration and interaction processes in pulsar magnetospheres. After an extended hiatus between satellite missions, the recently-launched AGILE mission and the upcoming Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) will allow gamma-ray tests of the theoretical models developed based on past discoveries. With its greatly improved sensitivity, better angular resolution, and larger energy reach than older instruments, GLAST LAT should detect dozens to hundreds of new gamma-ray pulsars and measure luminosities, light curves, and phase-resolved spectra with unprecedented resolution. It will also have the potential to find radio-quiet pulsars like Geminga, using blind search techniques. Cooperation with radio and X-ray pulsar astronomers is an important aspect of the LAT team's planning for pulsar studies.

  6. X-ray cardiovascular examination apparatus

    International Nuclear Information System (INIS)

    1977-01-01

    An X-ray source is mounted in an enclosure for angulating longitudinally about a horizontal axis. An X-ray-permeable, patient-supporting table is mounted on the top of the enclosure for executing lateral and longitudinal movements. An X-ray image-receiving device such as an X-ray image intensifier is mounted above the table on a vertically movable arm which is on a longitudinally movable carriage. Electric control means are provided for angulating the X-ray source and image intensifier synchronously as the image intensifier system is shifted longitudinally or vertically such that the central ray from the X-ray source is kept intensifier

  7. Effective X-ray beam size measurements of an X-ray tube and polycapillary X-ray lens system using a scanning X-ray fluorescence method

    Energy Technology Data Exchange (ETDEWEB)

    Gherase, Mihai R., E-mail: mgherase@csufresno.edu; Vargas, Andres Felipe

    2017-03-15

    Size measurements of an X-ray beam produced by an integrated polycapillary X-ray lens (PXL) and X-ray tube system were performed by means of a scanning X-ray fluorescence (SXRF) method using three different metallic wires. The beam size was obtained by fitting the SXRF data with the analytical convolution between a Gaussian and a constant functions. For each chemical element in the wire an effective energy was calculated based on the incident X-ray spectrum and its photoelectric cross section. The proposed method can be used to measure the effective X-ray beam size in XRF microscopy studies.

  8. Center for X-Ray Optics, 1986

    International Nuclear Information System (INIS)

    1987-07-01

    The Center for X-Ray Optics has made substantial progress during the past year on the development of very high resolution x-ray technologies, the generation of coherent radiation at x-ray wavelengths, and, based on these new developments, had embarked on several scientific investigations that would not otherwise have been possible. The investigations covered in this report are topics on x-ray sources, x-ray imaging and applications, soft x-ray spectroscopy, synchrotron radiation, advanced light source and magnet structures for undulators and wigglers

  9. X-ray tube arrangements

    International Nuclear Information System (INIS)

    Gillard, R.G.

    1980-01-01

    A technique for ensuring the rapid correction of both amplitude and offset errors in the deflectional movement of an electron beam along an X-ray emissive target is described. The movement is monitored at at least two positions during a sweep and differences, between the two movements and a desired movement, at these positions are combined in different proportions to produce a corrective servo signal. Such arrangements find application, for example, in computerised tomographic scanners. (author)

  10. X-ray Sensitive Material

    Science.gov (United States)

    2015-12-01

    Reference 3), inorganic semiconductors (silicon [Si], cadmium zinc telluride [CdZnTe]) (Reference 4) and selenium (References 5 and 6), Ne-Xe...data showing photocurrent generation. Reports on other X-ray photoconductors, such as amorphous selenium , typically show such data (Reference 34). We...that BiI3 content does contribute to surface discharge; however, further work is warranted to measure the photocurrent. Selenium films used for

  11. Diffractive X-ray Telescopes

    OpenAIRE

    Skinner, Gerald K.

    2010-01-01

    Diffractive X-ray telescopes using zone plates, phase Fresnel lenses, or related optical elements have the potential to provide astronomers with true imaging capability with resolution several orders of magnitude better than available in any other waveband. Lenses that would be relatively easy to fabricate could have an angular resolution of the order of micro-arc-seconds or even better, that would allow, for example, imaging of the distorted space- time in the immediate vicinity of the super...

  12. Smart X-ray optics

    International Nuclear Information System (INIS)

    Michette, A G; Pfauntsch, S J; Sahraei, S; Shand, M; Morrison, G R; Hart, D; Vojnovic, B; Stevenson, T; Parkes, W; Dunare, C; Willingale, R; Feldman, C; Button, T; Zhang, D; Rodriguez-Sanmartin, D; Wang, H

    2009-01-01

    This paper describes reflective adaptive/active optics for applications including studies of biological radiation damage. The optics work on the polycapillary principle, but use arrays of channels in thin silicon. For optimum performance the x-rays should reflect once off a channel wall in each of two successive arrays. This reduces aberrations since then the Abbe sine condition is approximately satisfied. Adaptivity is achieved by flexing the arrays via piezo actuation, providing further aberration reduction and controllable focal length.

  13. Pulsar magnetospheres in binary systems

    Science.gov (United States)

    Ershkovich, A. I.; Dolan, J. F.

    1985-01-01

    The criterion for stability of a tangential discontinuity interface in a magnetized, perfectly conducting inviscid plasma is investigated by deriving the dispersion equation including the effects of both gravitational and centrifugal acceleration. The results are applied to neutron star magnetospheres in X-ray binaries. The Kelvin-Helmholtz instability appears to be important in determining whether MHD waves of large amplitude generated by instability may intermix the plasma effectively, resulting in accretion onto the whole star as suggested by Arons and Lea and leading to no X-ray pulsar behavior.

  14. X-Ray Crystallography Reagent

    Science.gov (United States)

    Morrison, Dennis R. (Inventor); Mosier, Benjamin (Inventor)

    2003-01-01

    Microcapsules prepared by encapsulating an aqueous solution of a protein, drug or other bioactive substance inside a semi-permeable membrane by are disclosed. The microcapsules are formed by interfacial coacervation under conditions where the shear forces are limited to 0-100 dynes per square centimeter at the interface. By placing the microcapsules in a high osmotic dewatering solution. the protein solution is gradually made saturated and then supersaturated. and the controlled nucleation and crystallization of the protein is achieved. The crystal-filled microcapsules prepared by this method can be conveniently harvested and stored while keeping the encapsulated crystals in essentially pristine condition due to the rugged. protective membrane. Because the membrane components themselves are x-ray transparent, large crystal-containing microcapsules can be individually selected, mounted in x-ray capillary tubes and subjected to high energy x-ray diffraction studies to determine the 3-D smucture of the protein molecules. Certain embodiments of the microcapsules of the invention have composite polymeric outer membranes which are somewhat elastic, water insoluble, permeable only to water, salts, and low molecular weight molecules and are structurally stable in fluid shear forces typically encountered in the human vascular system.

  15. The structure of liquid semiconductors, superionic conductors and glasses by neutron scattering, X-ray diffraction and extended X-ray absorption fine structure

    International Nuclear Information System (INIS)

    Buchanan, P.

    2001-09-01

    A study of the applicability of modern X-ray and neutron scattering techniques to the study of the structure of liquid semiconductors and glasses has been made. The results demonstrate how neutron scattering with isotopic substitution (NDIS), anomalous X-ray scattering and Extended X-ray Absorption Fine Structure (EXAFS) can be successfully used to elucidate the structure of materials that cannot be studied by NDIS alone. The local coordination structure of Ag 2 Se in its room temperature, superionic and liquid phases has been determined using the EXAFS technique. This EXAFS data have been combined with previously available neutron diffraction data to provide a refinement of the structure obtained through neutron diffraction alone. The structure of GeO 2 has been determined to the full partial structure factor level using a combination of anomalous X-ray scattering and neutron diffraction measurements. The data are in good agreement with previously obtained results. The partial structure factors of P 40 Se 60 and P 50 Se 50 have been determined to the first order difference level using the anomalous X-ray diffraction technique. The structure of liquid Ga 2 Te 3 has been determined to the partial structure factor level using combined neutron diffraction with isotopic substitution (NDIS) and anomalous X-ray diffraction. The structure of liquid FeSe 2 has been determined to the first order difference level using the NDIS technique alone. The structure of liquid FeTe 2 was determined at the total structure factor level using neutron diffraction in order to estimate the effect of chalcogenide ion size on the structure. The results demonstrate the feasibility of the additional structural determination techniques for disordered materials made possible through the development of third generation X-ray synchrotron sources. (author)

  16. Aspergillosis - chest x-ray (image)

    Science.gov (United States)

    ... usually occurs in immunocompromised individuals. Here, a chest x-ray shows that the fungus has invaded the lung ... are usually seen as black areas on an x-ray. The cloudiness on the left side of this ...

  17. Soft x-ray Planetary Imager

    Data.gov (United States)

    National Aeronautics and Space Administration — The project is to prototype a soft X-ray Imager for planetary applications that has the sensitivity to observe solar system sources of soft  X-ray emission. A strong...

  18. Stabilized x-ray generator power supply

    International Nuclear Information System (INIS)

    Saha, Subimal; Purushotham, K.V.; Bose, S.K.

    1986-01-01

    X-ray diffraction and X-ray fluorescence analysis are very much adopted in laboratories to determine the type and structure of the constituent compounds in solid materials, chemical composition of materials, stress developed on metals etc. These experiments need X-ray beam of fixed intensity and wave length. This can only be achieved by X-ray generator having highly stabilized tube voltage and tube current. This paper describes how X-ray tube high voltage and electron beam current are stabilized. This paper also highlights generation of X-rays, diffractometry and X-ray fluorescence analysis and their wide applications. Principle of operation for stabilizing the X-ray tube voltage and current, different protection circuits adopted, special features of the mains H.V. transformer and H.T. tank are described in this report. (author)

  19. X-ray electromagnetic application technology

    International Nuclear Information System (INIS)

    2011-01-01

    The investigating committee aimed at research on electromagnetic fields in functional devices and X-ray fibers for efficient coherent X-ray generation and their material science, high-precision manufacturing, particularly for X-ray electromagnetic application technology from January 2006 to December 2008. In this report, we describe our research results, in particular, on the topics of synchrotron radiation and free-electron laser, Saga Synchrotron Project, X-ray waveguides and waveguide-based lens-less hard-X-ray imaging, X-ray nanofocusing for capillaries and zone plates, dispersion characteristics in photonics crystal consisting of periodic atoms for nanometer waveguides, electromagnetic characteristics of grid structures for scattering fields of nano-meter electromagnetic waves and X-rays, FDTD parallel computing of fundamental scattering and attenuation characteristics of X-ray for medical imaging diagnosis, orthogonal relations of electromagnetic fields including evanescent field in dispersive medium. (author)

  20. A possible state transition in the low-mass X-ray binary XSS J12270-4859

    Science.gov (United States)

    Bassa, C. G.; Patruno, A.; Hessels, J. W. T.; Archibald, A. M.; Mahony, E. K.; Monard, B.; Keane, E. F.; Bogdanov, S.; Stappers, B. W.; Janssen, G. H.; Tendulkar, S.

    2013-12-01

    Spurred by the recent state change in the "missing link" pulsar binary system PSR J1023+0038 (ATel #5513, #5514, #5515, #5516; Stappers et al. 2013, arXiv:1311.7506; Patruno et al. 2013, arXiv:1310.7549) we report on optical, radio, X-ray and gamma-ray observations of the low-mass X-ray binary XSS J12270-4859, conducted between 2012 March 29 and 2013 December 10.

  1. Chandra X-Ray Observations of the Jovian System

    Science.gov (United States)

    Elsner, R. F.; Waite, J. H.; Crary, F.; Majeed, T.; Gladstone, G. R.; Lewis, W. S.; Ford, P. G.; Howell, R. R.; Johnson, R. E.; Bhardwaj, A.; hide

    2002-01-01

    High-spatial resolution Chandra x-ray observations have demonstrated that most of Jupiter's northern auroral x-rays come from a hot spot located significantly poleward of the latitudes connected to the inner magnetosphere. This hot spot appears fixed in magnetic latitude and longitude and coincides with a region exhibiting anomalous ultraviolet and infrared emissions. The hot spot also exhibited approximately 45 minute quasi-periodic oscillations, a period similar to those reported for high-latitude radio and energetic electron bursts observed by near-Jupiter spacecraft. These results invalidate the idea that jovian auroral x-ray emissions are mainly excited by steady precipitation of energetic heavy ions from the inner magnetosphere. Instead, the x-rays appear to result from currently unexplained processes in the outer magnetosphere that produce highly localized and highly variable emissions over an extremely wide range of wavelengths. The Chandra observations also revealed for the first time x-ray emission (about 0.1 GW) from the Io Plasma Torus, as well as very faint x-ray emission (about 1-2 MW) from the Galilean moons Io, Europa, and possibly Ganymede. The emission from the moons is almost certainly due to Kalpha emission of surface atoms (and possibly impact atoms) excited by the impact of highly energetic protons, oxygen, and sulfur atoms and ions from the Torus. The Torus emission is less well understood at present, although bremsstrahlung from the non-thermal tail of the electron distribution may provide a significant fraction. In any case, further observations, already accepted and in the process of being planned, with Chandra, some with the moderate energy resolution of the CCD camera, together with simultaneous Hubble Space Telescope observations and hopefully ground-based IRTF observations should soon provide greater insight into these various processes.

  2. Development of quantitative x-ray microtomography

    International Nuclear Information System (INIS)

    Deckman, H.W.; Dunsmuir, J.A.; D'Amico, K.L.; Ferguson, S.R.; Flannery, B.P.

    1990-01-01

    The authors have developed several x-ray microtomography systems which function as quantitative three dimensional x-ray microscopes. In this paper the authors describe the evolutionary path followed from making the first high resolution experimental microscopes to later generations which can be routinely used for investigating materials. Developing the instrumentation for reliable quantitative x-ray microscopy using synchrotron and laboratory based x-ray sources has led to other imaging modalities for obtaining temporal and spatial two dimensional information

  3. X-ray fluorescence with synchrotron radiation

    International Nuclear Information System (INIS)

    Raman, S.; Sparks, C.J. Jr.

    1978-01-01

    An experimental set-up for x-ray fluorescence analysis with synchrotron radiation was built and installed at the Stanford Synchrotron Radiation Project. X-ray spectra were taken from numerous and varied samples in order to assess the potential of synchrotron radiation as an excitation source for multielement x-ray fluorescence analysis. For many applications, the synchrotron radiation technique is shown to be superior to other x-ray fluorescence methods, especially those employing electrons and protons as excitation sources

  4. Phase-sensitive X-ray imager

    Science.gov (United States)

    Baker, Kevin Louis

    2013-01-08

    X-ray phase sensitive wave-front sensor techniques are detailed that are capable of measuring the entire two-dimensional x-ray electric field, both the amplitude and phase, with a single measurement. These Hartmann sensing and 2-D Shear interferometry wave-front sensors do not require a temporally coherent source and are therefore compatible with x-ray tubes and also with laser-produced or x-pinch x-ray sources.

  5. Element specific X-ray fluorescene microtomography

    OpenAIRE

    Günzler, Til Florian

    2003-01-01

    X-ray fluorescence is widely known as an element-specific scanning analytic tool. It is used in many fields of science and technology and has given major new insights into different problems. The relatively large penetration depth of x rays into matter makes them ideally suited for tomography. The combination of x-ray fluorescence analysis and scanning microtomography, hereafter called x-ray fluorescence microtomography, has been further developed and improved in this work. Employing the newl...

  6. X-ray diagnostics - benefits and risks

    International Nuclear Information System (INIS)

    Bartholomaeus, Melanie

    2016-01-01

    The brochure on benefits and risks of X-ray diagnostics discusses the following issues: X radiation - a pioneering discovery and medical sensation, fundamentals of X radiation, frequency of X-ray examinations in Germany in relation to CT imaging, radiation doses resulting from X-ray diagnostics, benefits of X-ray diagnostics - indication and examples, risks - measures for radiation exposure reductions, avoidance of unnecessary examinations.

  7. The Beginnings of X-ray Crystallography

    Indian Academy of Sciences (India)

    IAS Admin

    The Beginnings of X-ray Crystallography. A Profile on the Two Braggs. Those were the days when Science was hovering around the wave–particle duality. William. Henry Bragg was toying with the idea that X-rays are particles and the observation made by Max von Laue that X-rays are diffracted by crystals could indeed ...

  8. Center for X-ray Optics, 1988

    Energy Technology Data Exchange (ETDEWEB)

    1989-04-01

    This report briefly reviews the following topics: soft-x-ray imaging; reflective optics for hard x-rays; coherent XUV sources; spectroscopy with x-rays; detectors for coronary artery imaging; synchrotron-radiation optics; and support for the advanced light source.

  9. X-Ray Exam: Femur (Upper Leg)

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español X-Ray Exam: Femur (Upper Leg) KidsHealth / For Parents / X- ... Muscles, and Joints Broken Bones Getting an X-ray (Video) X-Ray (Video) View more Partner Message About Us ...

  10. X-Rays, Pregnancy and You

    Science.gov (United States)

    ... Emitting Products and Procedures Medical Imaging Medical X-ray Imaging X-Rays, Pregnancy and You Share Tweet Linkedin Pin it ... the decision with your doctor. What Kind of X-Rays Can Affect the Unborn Child? During most x- ...

  11. X-Ray Exam: Scoliosis (For Parents)

    Science.gov (United States)

    ... for Educators Search English Español X-Ray Exam: Scoliosis KidsHealth / For Parents / X-Ray Exam: Scoliosis What's in this article? What It Is Why ... You Have Questions Print What It Is A scoliosis X-ray is a relatively safe and painless ...

  12. Cryotomography x-ray microscopy state

    Science.gov (United States)

    Le Gros, Mark; Larabell, Carolyn A.

    2010-10-26

    An x-ray microscope stage enables alignment of a sample about a rotation axis to enable three dimensional tomographic imaging of the sample using an x-ray microscope. A heat exchanger assembly provides cooled gas to a sample during x-ray microscopic imaging.

  13. Student X-Ray Fluorescence Experiments

    Science.gov (United States)

    Fetzer, Homer D.; And Others

    1975-01-01

    Describes the experimental arrangement for x-ray analysis of samples which involves the following: the radioisotopic x-ray disk source; a student-built fluorescence chamber; the energy dispersive x-ray detector, linear amplifier and bias supply; and a multichannel pulse height analyzer. (GS)

  14. Electron beam parallel X-ray generator

    Science.gov (United States)

    Payne, P.

    1967-01-01

    Broad X ray source produces a highly collimated beam of low energy X rays - a beam with 2 to 5 arc minutes of divergence at energies between 1 and 6 keV in less than 5 feet. The X ray beam is generated by electron bombardment of a target from a large area electron gun.

  15. Total reflection x-ray fluorescence (TXRF)

    International Nuclear Information System (INIS)

    Hockett, R.S.

    1995-01-01

    Total reflection X-Ray Fluorescence (TXRF) is a glancing x-ray analytical technique which is used primarily to measure surface metal contamination on semiconductor substrates. This is a review of Total reflection X-Ray Fluorescence (TXRF) applications for silicon semiconductor processing. In addition, some comments are made about the future of TXRF, and in particular, synchrotron radiation TXRF (SR-TXRF)

  16. Automatic weld joint X-ray inspection

    International Nuclear Information System (INIS)

    Richter, H.U.; Linke, D.; Siems, K.D.; Kruse, H.; Schuetze, E.

    1990-01-01

    A gantry mounted robotic x-ray inspection unit has been developed for the series testing of small and medium sized welded components (pipe bends and nozzles). The unit features computer controlled positioning of the x-ray tube and x-ray image amplifier. Image quality classes 2 and even 1 could be achieved without difficulty. (author)

  17. Evidence for Precession due to Supercritical Accretion in Ultraluminous X-Ray Sources

    Science.gov (United States)

    Weng, Shan-Shan; Feng, Hua

    2018-02-01

    Most ultraluminous X-ray sources (ULXs) are thought to be supercritical accreting compact objects, where massive outflows are inevitable. Using the long-term monitoring data with the Swift X-ray Telescope, we identified a common feature in bright, hard ULXs: they display a quasi-periodic modulation in their hard X-ray band but not in their soft band. As a result, some sources show a bimodal distribution on the hardness intensity map. We argue that these model-independent results can be well interpreted in a picture that involves supercritical accretion with precession, where the hard X-ray emission from the central funnel is more or less beamed, while the soft X-rays may arise from the photosphere of the massive outflow and be nearly isotropic. It implies that precession may be ubiquitous in supercritical systems, such as the Galactic microquasar SS 433. How the hard X-rays are modulated can be used to constrain the angular distribution of the hard X-ray emission and the geometry of the accretion flow. We also find that two ULX pulsars (NGC 5907 ULX-1 and NGC 7793 P13) show similar behaviors but no bimodal distribution, which may imply that they have a different beaming shape or mechanism.

  18. Pulsating X-ray sources

    International Nuclear Information System (INIS)

    Trumper, J.

    1986-01-01

    The discovery of pulsating X-ray sources in close binary systems was one of the major achievements of the Uhuru satellite. Today one knows about two dozens of these sources with pulsational periods between 69 ms and 835 s. In most cases the X-ray source orbits an early-type star of high mass having a rather large optical luminosity. There are a few exceptions: GX1+4 is associated with a late-type (M6) giant, 4U1616-67 has a comparison of very low mass (≤ 0.1 M/sub sub solar/), and Her X-1 is a borderline case, since its counterpart HZ Her is an A-F star of -- 2/sub sub solar/. It is clear that the X-ray sources in these systems are rotating magnetized neutron stars accreting from their normal companion, probably in most cases via Roche lobe overflow which leads to the formation of an accretion disk. In some cases (e.g. Vela X-1) the accretion proceeds via a stellar wind. Pulsations occur because in the immediate vicinity of the neutron star the matter is funneled by the strong magnetic field onto the polar caps where a hot and very luminous plasma is formed. Typical luminosities are huge, namely of the order of 10/sup 37/ erg/s which are radiated at effective temperatures of -- 10/sup 8/ K. Much has been learned about these systems and about neutron stars from studies of pulse arrival times and source spectra. The author briefly summarizes some of the major results and discusses some very recent results obtained with EXOSAT

  19. XMM-Newton Observations of Four Millisecond Pulsars

    Science.gov (United States)

    Zavlin, Vyacheslav E.

    2005-01-01

    I present an analysis of the XMM-Newton observations of four millisecond pulsars, J0437-4715, J2124-3358, J1024-0719, and J0034-0534. The new data provide strong evidence of thermal emission in the X-ray flux detected from the first three objects. This thermal component is best interpreted as radiation from pulsar polar caps covered with a nonmagnetic hydrogen atmosphere. A nonthermal power-law component, dominating at energies E greater than or equal to 3 keV, can also be present in the detected X-ray emission. For PSR J0437-4715, the timing analysis reveals that the shape and pulsed fraction of the pulsar light curves are energy dependent. This, together with the results obtained from the phase-resolved spectroscopy, supports the two-component (thermal plus nonthermal) interpretation of the pulsar's X-ray radiation. Highly significant pulsations have been found in the X-ray flux of PSRs 52124-3358 and 51024-0719. For PSR 50034-0534, a possible X-ray counterpart of the radio pulsar has been suggested. The inferred properties of the detected thermal emission are compared with predictions of radio pulsar models.

  20. Identifying Bright X-Ray Beasts

    Science.gov (United States)

    Kohler, Susanna

    2017-10-01

    Ultraluminous X-ray sources (ULXs) are astronomical sources of X-rays that, while dimmer than active galactic nuclei, are nonetheless brighter than any known stellar process. What are these beasts and why do they shine so brightly?Exceeding the LimitFirst discovered in the 1980s, ULXs are rare sources that have nonetheless been found in all types of galaxies. Though the bright X-ray radiation seems likely to be coming from compact objects accreting gas, theres a problem with this theory: ULXs outshine the Eddington luminosity for stellar-mass compact objects. This means that a stellar-mass object couldnt emit this much radiation isotropically without blowing itself apart.There are two alternative explanations commonly proposed for ULXs:Rather than being accreting stellar-mass compact objects, they are accreting intermediate-mass black holes. A hypothetical black hole of 100 solar masses or more would have a much higher Eddington luminosity than a stellar-mass black hole, making the luminosities that we observe from ULXs feasible.An example of one of the common routes the authors find for a binary system to become a ULX. In this case, the binary begins as two main sequence stars. As one star evolves off the main sequence, the binary undergoes a common envelope phase and a stage of mass transfer. The star ends its life as a supernova, and the resulting neutron star then accretes matter from the main sequence star as a ULX. [Wiktorowicz et al. 2017]They are ordinary X-ray binaries (a stellar-mass compact object accreting matter from a companion star), but they are undergoing a short phase of extreme accretion. During this time, their emission is beamed into jets, making them appear brighter than the Eddington luminosity.Clues from a New DiscoveryA few years ago, a new discovery shed some light on ULXs: M82 X-2, a pulsing ULX. Two more pulsing ULXs have been discovered since then, demonstrating that at least some ULXs contain pulsars i.e., neutron stars as the

  1. Protonium X-ray spectroscopy

    CERN Document Server

    Gotta, D

    1999-01-01

    The Lyman and Balmer transitions from antiprotonic hydrogen and deuterium were studied extensively at the low-energy-antiproton ring LEAR at CERN in order to determine the strong interaction effects. A first series of experiments $9 was performed with semiconductor and gaseous X-ray detectors. In the last years of LEAR operation using a Bragg crystal spectrometer, strong interaction parameters in the 2p states of antiprotonic hydrogen and deuterium were measured $9 directly. The results of the measurements support the meson-exchange models describing the medium and long range part of the nucleon-antinucleon interaction. (39 refs).

  2. X-ray intensifying screens

    International Nuclear Information System (INIS)

    Bossomaier, T.R.J.; Sangway, P.C.

    1979-01-01

    It is claimed that stabilization of X-ray intensifying screens against discolouration and hydrolysis of lanthanum or gadolinium oxyhalide phosphors can be achieved by incorporating into the phosphor/binder formulation a compound containing free epoxy groups. Suitable epoxy compounds include gamma glycidoxy trimethoxy silane and dimethyl di(m-glycidoxy methylphenyl) methane. The oxyhalide may be activated by Tb, Tm or Yb and may be mixed with other phosphors. Plasticisers and organo-tin stabilisers for the formulation are given. Many binders are specified, preferably these should not react with the free epoxy groups. (UK)

  3. Method for spatially modulating X-ray pulses using MEMS-based X-ray optics

    Science.gov (United States)

    Lopez, Daniel; Shenoy, Gopal; Wang, Jin; Walko, Donald A.; Jung, Il-Woong; Mukhopadhyay, Deepkishore

    2015-03-10

    A method and apparatus are provided for spatially modulating X-rays or X-ray pulses using microelectromechanical systems (MEMS) based X-ray optics. A torsionally-oscillating MEMS micromirror and a method of leveraging the grazing-angle reflection property are provided to modulate X-ray pulses with a high-degree of controllability.

  4. Picosecond x-ray streak camera studies

    International Nuclear Information System (INIS)

    Kasyanov, Yu.S.; Malyutin, A.A.; Richardson, M.C.; Chevokin, V.K.

    1975-01-01

    Some initial results of direct measurement of picosecond x-ray emission from laser-produced plasmas are presented. A PIM-UMI 93 image converter tube, incorporating an x-ray sensitive photocathode, linear deflection, and three stages of image amplification was used to analyse the x-ray radiation emanating from plasmas produced from solid Ti targets by single high-intensity picosecond laser pulses. From such plasmas, the x-ray emission typically persisted for times of 60psec. However, it is shown that this detection system should be capable of resolving x-ray phenomena of much shorter duration. (author)

  5. Si(Li) X-ray detector

    International Nuclear Information System (INIS)

    Yuan Xianglin; Li Zhiyong; Hong Xiuse

    1990-08-01

    The fabrication technology of the 10∼80 mm 2 Si(Li) X-ray detectors are described and some problems concerning technology and measurement are discussed. The specifications of the detectors are shown as well. The Si(Li) X-ray detector is a kind of low energy X-ray detectors. Owing to very high energy resolution, fine linearity and high detection efficiency in the range of low energy X-rays, it is widely used in the fields of nuclear physics, medicine, geology and environmental protection, etc,. It is also a kernel component for the scanning electron microscope and X-ray fluorescence analysis systems

  6. NIKOLA TESLA AND THE X-RAY

    OpenAIRE

    Rade R. Babic

    2005-01-01

    After professor Wilhelm Konrad Röntgen published his study of an x-ray discovery (Academy Bulletin, Berlin, 08. 11. 1895.), Nikola Tesla published his first study of an x-ray on the 11th of March in 1896. (X-ray, Electrical Review). Until the 11th of August in 1897 he had published ten studies on this subject. All Tesla,s x-ray studies were experimental, which is specific to his work. Studying the nature of the x-ray, he established a new medical branch-radiology. He wrote:” There’s no doubt...

  7. Miniature x-ray point source for alignment and calibration of x-ray optics

    International Nuclear Information System (INIS)

    Price, R.H.; Boyle, M.J.; Glaros, S.S.

    1977-01-01

    A miniature x-ray point source of high brightness similar to that of Rovinsky, et al. is described. One version of the x-ray source is used to align the x-ray optics on the Argus and Shiva laser systems. A second version is used to determine the spatial and spectral transmission functions of the x-ray optics. The spatial and spectral characteristics of the x-ray emission from the x-ray point source are described. The physical constraints including size, intensity and thermal limitations, and useful lifetime are discussed. The alignment and calibration techniques for various x-ray optics and detector combinations are described

  8. X-ray and gamma radiography devices

    International Nuclear Information System (INIS)

    Abdul Nassir Ibrahim; Azali Muhammad; Ab. Razak Hamzah; Abd. Aziz Mohamed; Mohamad Pauzi Ismail

    2008-01-01

    When we are using this technique, we also must familiar with the device and instrument that used such as gamma projector, crawler, x-ray tubes and others. So this chapter discussed detailed on device used for radiography work. For the x-ray and gamma, their characteristics are same but the source to produce is a big different. X-ray produced from the machine meanwhile, gamma produce from the source such as Co-60 and IR-192. Both are electromagnetic waves. So, the reader can have some knowledge on what is x-ray tube, discrete x-ray and characteristic x-ray, how the machine works and how to control a machine, what is source for gamma emitter, how to handle the projector and lastly difference between x-ray and gamma. Of course this cannot be with the theory only, so detailed must be learned practically.

  9. X ray imaging microscope for cancer research

    Science.gov (United States)

    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.

  10. Ultraviolet and optical observations of the HDE 245770/A0535+26 system during an X-ray flare

    International Nuclear Information System (INIS)

    Giovannelli, F.; Ferrari-Toniolo, M.; Giangrande, A.; Persi, P.; Bartolini, C.; Guarnieri, A.; Piccioni, A.

    1981-01-01

    We present high and low dispersion UV spectra of HDE 245770, which is the optical counterpart of the recurrent transient X-ray pulsar A0535+26, during a decay of an X-ray flare. UBV photometric measurements and medium dispersion optical spectra were simultaneously obtained. The energy distribution of the star in the 12-10 micron range is compared with the models of Kurucz and Poeckert and Marlborough. In this phase, HDE 245770 does not show evaluable variations with respect to the quiescent X-ray phase. (orig.)

  11. Submicron X-ray diffraction

    International Nuclear Information System (INIS)

    MacDowell, Alastair; Celestre, Richard; Tamura, Nobumichi; Spolenak, Ralph; Valek, Bryan; Brown, Walter; Bravman, John; Padmore, Howard; Batterman, Boris; Patel, Jamshed

    2000-01-01

    At the Advanced Light Source in Berkeley the authors have instrumented a beam line that is devoted exclusively to x-ray micro diffraction problems. By micro diffraction they mean those classes of problems in Physics and Materials Science that require x-ray beam sizes in the sub-micron range. The instrument is for instance, capable of probing a sub-micron size volume inside micron sized aluminum metal grains buried under a silicon dioxide insulating layer. The resulting Laue pattern is collected on a large area CCD detector and automatically indexed to yield the grain orientation and deviatoric (distortional) strain tensor of this sub-micron volume. A four-crystal monochromator is then inserted into the beam, which allows monochromatic light to illuminate the same part of the sample. Measurement of diffracted photon energy allows for the determination of d spacings. The combination of white and monochromatic beam measurements allow for the determination of the total strain/stress tensor (6 components) inside each sub-micron sized illuminated volume of the sample

  12. X-Ray Detection and Processing Models for Spacecraft Navigation and Timing

    Science.gov (United States)

    Sheikh, Suneel; Hanson, John

    2013-01-01

    The current primary method of deepspace navigation is the NASA Deep Space Network (DSN). High-performance navigation is achieved using Delta Differential One-Way Range techniques that utilize simultaneous observations from multiple DSN sites, and incorporate observations of quasars near the line-of-sight to a spacecraft in order to improve the range and angle measurement accuracies. Over the past four decades, x-ray astronomers have identified a number of xray pulsars with pulsed emissions having stabilities comparable to atomic clocks. The x-ray pulsar-based navigation and time determination (XNAV) system uses phase measurements from these sources to establish autonomously the position of the detector, and thus the spacecraft, relative to a known reference frame, much as the Global Positioning System (GPS) uses phase measurements from radio signals from several satellites to establish the position of the user relative to an Earth-centered fixed frame of reference. While a GPS receiver uses an antenna to detect the radio signals, XNAV uses a detector array to capture the individual xray photons from the x-ray pulsars. The navigation solution relies on detailed xray source models, signal processing, navigation and timing algorithms, and analytical tools that form the basis of an autonomous XNAV system. Through previous XNAV development efforts, some techniques have been established to utilize a pulsar pulse time-of-arrival (TOA) measurement to correct a position estimate. One well-studied approach, based upon Kalman filter methods, optimally adjusts a dynamic orbit propagation solution based upon the offset in measured and predicted pulse TOA. In this delta position estimator scheme, previously estimated values of spacecraft position and velocity are utilized from an onboard orbit propagator. Using these estimated values, the detected arrival times at the spacecraft of pulses from a pulsar are compared to the predicted arrival times defined by the pulsar s pulse

  13. Portable X-ray reflectometer using a low power polychromatic X-ray tube

    International Nuclear Information System (INIS)

    Ohnishi, Tsunemasa; Imashuku, Susumu; Yuge, Koretaka; Kawai, Jun; Shimura, Naomi

    2014-01-01

    We developed a portable X-ray reflectometer which measures energy dispersive X-ray reflectivity using a polychromatic X-rays from a low power (a few watts) X-ray tube and a silicon drift detector. A thin Cu film on silicon substrate using the portable reflectometer was measured. A fringe pattern was shifted due to the change of the X-ray incident angle. The measured peak position of the fringe pattern was satisfactorily agreed with the calculation. (author)

  14. Full-field transmission x-ray imaging with confocal polycapillary x-ray optics

    OpenAIRE

    Sun, Tianxi; MacDonald, C. A.

    2013-01-01

    A transmission x-ray imaging setup based on a confocal combination of a polycapillary focusing x-ray optic followed by a polycapillary collimating x-ray optic was designed and demonstrated to have good resolution, better than the unmagnified pixel size and unlimited by the x-ray tube spot size. This imaging setup has potential application in x-ray imaging for small samples, for example, for histology specimens.

  15. Coherent radiation from pulsars

    International Nuclear Information System (INIS)

    Cox, J.L. Jr.

    1979-01-01

    Interaction between a relativistic electrom stream and a plasma under conditions believed to exist in pulsar magnetospheres is shown to result in the simultaneous emission of coherent curvature radiation at radio wavelengths and incoherent curvature radiation at X-ray wavelengths from the same spatial volume. It is found that such a stream can propagate through a plasma parallel to a very strong magnetic field only if its length is less than a critical length L/sub asterisk/ic. Charge induced in the plasma by the stream co-moves with the stream and has the same limitation in longitudinal extent. The resultant charge bunching is sufficient to cause the relatively low energy plasma particles to radiate at radio wavelengths coherently while the relatively high energy stream particles radiate at X-ray wavelengths incoherently as the stream-plasma system moves along curved magnetic field lines. The effective number of coherently radiating particles per bunch is estimated to be approx.10 14 --10 15 for a tupical pulsar

  16. Diffractive X-Ray Telescopes

    International Nuclear Information System (INIS)

    Skinner, G.K.; Skinner, G.K

    2010-01-01

    Diffractive X-ray telescopes using zone plates, phase Fresnel lenses, or related optical elements have the potential to provide astronomers with true imaging capability with resolution several orders of magnitude better than available in any other waveband. Lenses that would be relatively easy to fabricate could have an angular resolution of the order of micro arc seconds or even better, that would allow, for example, imaging of the distorted spacetime in the immediate vicinity of the supermassive black holes in the center of active galaxies What then is precluding their immediate adoption Extremely long focal lengths, very limited bandwidth, and difficulty stabilizing the image are the main problems. The history and status of the development of such lenses is reviewed here and the prospects for managing the challenges that they present are discussed atmospheric absorption

  17. Monitoring Baby - Listening in on the Youngest Known Pulsar

    Science.gov (United States)

    Gotthelf, Eric

    We have discovered a most remarkable young pulsar, PSR J1846-0258, in the core of a Crab-like pulsar wind nebula at the center of the bright shell-type supernova remnant Kes 75. Based on its spin-down rate and X- ray spectrum, PSR J1846-0258 is likely the youngest known rotation- powered pulsar. Compared to the Crab pulsar, however, its period, spin- down rate, and spin-down to X-ray luminosity conversion efficiency are each an order of magnitude greater, likely the result of its extreme magnetic field, above the quantum critical threshold. We propose to continue our monitoring campaign of PSR J1846-0258 to measure the braking index, characterize its timing noise, and search for evidence of glitches. This pulsar provides important insight into the evolution of the youngest NS-SNR systems.

  18. Sensors for x-ray astronomy satellite

    International Nuclear Information System (INIS)

    Makino, Fumiyoshi; Kondo, Ichiro; Nishioka, Yonero; Kameda, Yoshihiko; Kubo, Masaki.

    1980-01-01

    For the purpose of observing the cosmic X-ray, the cosmic X-ray astronomy satellite (CORSA-b, named ''Hakucho'', Japanese for cygnus,) was launched Feb. 21, 1979 by Institute of Space and Aeronautical Science, University of Tokyo. The primary objectives of the satellite are: to perform panoramic survey of the space for X-ray bursts and to perform the spectral and temporal measurement of X-ray sources. The very soft X-ray sensor for X-ray observation and the horizon sensor for spacecraft attitude sensing were developed by Toshiba Corporation under technical support by University of Tokyo and Nagoya University for ''Hakucho''. The features of these sensors are outlined in this paper. (author)

  19. Handbook of X-Ray Data

    CERN Document Server

    Zschornack, Günter

    2007-01-01

    This sourcebook is intended as an X-ray data reference for scientists and engineers working in the field of energy or wavelength dispersive X-ray spectrometry and related fields of basic and applied research, technology, or process and quality controlling. In a concise and informative manner, the most important data connected with the emission of characteristic X-ray lines are tabulated for all elements up to Z = 95 (Americium). This includes X-ray energies, emission rates and widths as well as level characteristics such as binding energies, fluorescence yields, level widths and absorption edges. The tabulated data are characterized and, in most cases, evaluated. Furthermore, all important processes and phenomena connected with the production, emission and detection of characteristic X-rays are discussed. This reference book addresses all researchers and practitioners working with X-ray radiation and fills a gap in the available literature.

  20. Diffuse interstellar bands of unprecedented strength in the line of sight towards high-mass X-ray binary

    NARCIS (Netherlands)

    Cox, N.L.J.; Kaper, L.; Foing, B.H.; Ehrenfreund, P.

    2005-01-01

    High-resolution VLT/UVES spectra of the strongly reddened O supergiant companion to the X-ray pulsar 4U 1907+09 provide a unique opportunity to study the nature of the diffuse interstellar bands (DIBs) at unprecedented strength. We detect about 180 known DIBs, of which about 25

  1. A state change in the low-mass X-ray binary XSS J12270-4859

    NARCIS (Netherlands)

    Bassa, C.G.; Patruno, A.; Hessels, J.W.T.; Keane, E.F.; Monard, B.; Mahony, E.K.; Bogdanov, S.; Corbel, S.; Edwards, P.G.; Archibald, A.M.; Janssen, G.H.; Stappers, B.W.; Tendulkar, S.

    2014-01-01

    Millisecond radio pulsars acquire their rapid rotation rates through mass and angular momentum transfer in a low-mass X-ray binary system. Recent studies of PSR J1824−2452I and PSR J1023+0038 have observationally demonstrated this link, and they have also shown that such systems can repeatedly

  2. Switching X-Ray Tubes Remotely

    Science.gov (United States)

    Bulthuis, Ronald V.

    1990-01-01

    Convenient switch and relay circuit reduces risk of accidents. Proposed switching circuit for x-ray inspection system enables operator to change electrical connections to x-ray tubes remotely. Operator simply flips switch on conveniently-located selector box to change x-ray heads. Indicator lights on selector box show whether 160 or 320-kV head connected. Relays in changeover box provides proper voltages and coolants. Chance of making wrong connections and damaging equipment eliminated.

  3. The Livermore X-ray Laser Program

    International Nuclear Information System (INIS)

    Matthews, D.L.

    1992-01-01

    I will report on the status of x-ray laser development and its applications at Livermore. I will review some of our recent results and comment on where our future research is headed including plans for developing a compact x-ray laser users facility. Finally, I will briefly summarize the results of an X-ray Laser Applications Workshop that was held in San Francisco in January 1992

  4. X-ray data booklet. Revision

    Energy Technology Data Exchange (ETDEWEB)

    Vaughan, D. (ed.)

    1986-04-01

    A compilation of data is presented. Included are properties of the elements, electron binding energies, characteristic x-ray energies, fluorescence yields for K and L shells, Auger energies, energy levels for hydrogen-, helium-, and neonlike ions, scattering factors and mass absorption coefficients, and transmission bands of selected filters. Also included are selected reprints on scattering processes, x-ray sources, optics, x-ray detectors, and synchrotron radiation facilities. (WRF)

  5. Soft x-ray streak cameras

    International Nuclear Information System (INIS)

    Stradling, G.L.

    1988-01-01

    This paper is a discussion of the development and of the current state of the art in picosecond soft x-ray streak camera technology. Accomplishments from a number of institutions are discussed. X-ray streak cameras vary from standard visible streak camera designs in the use of an x-ray transmitting window and an x-ray sensitive photocathode. The spectral sensitivity range of these instruments includes portions of the near UV and extends from the subkilovolt x- ray region to several tens of kilovolts. Attendant challenges encountered in the design and use of x-ray streak cameras include the accommodation of high-voltage and vacuum requirements, as well as manipulation of a photocathode structure which is often fragile. The x-ray transmitting window is generally too fragile to withstand atmospheric pressure, necessitating active vacuum pumping and a vacuum line of sight to the x-ray signal source. Because of the difficulty of manipulating x-ray beams with conventional optics, as is done with visible light, the size of the photocathode sensing area, access to the front of the tube, the ability to insert the streak tube into a vacuum chamber and the capability to trigger the sweep with very short internal delay times are issues uniquely relevant to x-ray streak camera use. The physics of electron imaging may place more stringent limitations on the temporal and spatial resolution obtainable with x-ray photocathodes than with the visible counterpart. Other issues which are common to the entire streak camera community also concern the x-ray streak camera users and manufacturers

  6. Applications of soft x-ray lasers

    International Nuclear Information System (INIS)

    Skinner, C.H.

    1993-01-01

    The high brightness and short pulse duration of soft x-ray lasers provide unique advantages for novel applications. Imaging of biological specimens using x-ray lasers has been demonstrated by several groups. Other applications to fields such as chemistry, material science, plasma diagnostics, and lithography are beginning to emerge. We review the current status of soft x-ray lasers from the perspective of applications, and present an overview of the applications currently being developed

  7. Arrangement for X-ray shield

    International Nuclear Information System (INIS)

    1980-01-01

    X-ray screen unit consisting of a light transmissive carrier onto which scintillation material is deposited, which is able to generate light under the influence of incident X-ray irradiation, characterised in that the X-ray screen comprises a number of sectors, wherein the surface with respect to the incident X-radiation is maintained at an acute angle. (G.C.)

  8. X-ray spot film device

    International Nuclear Information System (INIS)

    Pury, T.; Tsen, M.L.S.; Gray, F.L.; Stehr, R.E.; Konle, R.L.

    1981-01-01

    Improvements are described in an X-ray spot film device which is used in conjunction with an X-ray table to make a selected number of radiographic exposures on a single film and to perform fluoroscopic examinations. To date, the spot film devices consist of two X-ray field defining masks, one of which is moved manually. The present device is more convenient to use and speeds up the procedure. (U.K.)

  9. Atom-resolving x-ray holography

    International Nuclear Information System (INIS)

    Adams, B.; Hiort, T.; Materlik, G.; Nishino, Y.; Novikov, D. V.

    2000-01-01

    The current state of atomic resolution x-ray holography is discussed on the basis of theory and experimental results. X-ray holography is theoretically described in quantum theory. Presently-used experimental implementations are shown together with the data analysis used. Reconstructions of experimental and simulated holograms are compared for a Cu 3 Au crystal structure. Rigorous experimental realizations of pure direct and reciprocal x-ray holography methods are demonstrated, and future developments and applications of the method are suggested

  10. Synchrotron x-ray microbeam characteristics for x-ray fluorescence analysis

    International Nuclear Information System (INIS)

    Iida, Atsuo; Noma, Takashi

    1995-01-01

    X-ray fluorescence analysis using a synchrotron x-ray microprobe has become an indispensable technique for non-destructive micro-analysis. One of the most important parameters that characterize the x-ray microbeam system for x-ray fluorescence analysis is the beam size. For practical analysis, however, the photon flux, the energy resolution and the available energy range are also crucial. Three types of x-ray microbeam systems, including monochromatic and continuum excitation systems, were compared with reference to the sensitivity, the minimum detection limit and the applicability to various types of x-ray spectroscopic analysis. 16 refs., 5 figs

  11. Automatic protein structure solution from weak X-ray data

    Science.gov (United States)

    Skubák, Pavol; Pannu, Navraj S.

    2013-11-01

    Determining new protein structures from X-ray diffraction data at low resolution or with a weak anomalous signal is a difficult and often an impossible task. Here we propose a multivariate algorithm that simultaneously combines the structure determination steps. In tests on over 140 real data sets from the protein data bank, we show that this combined approach can automatically build models where current algorithms fail, including an anisotropically diffracting 3.88 Å RNA polymerase II data set. The method seamlessly automates the process, is ideal for non-specialists and provides a mathematical framework for successfully combining various sources of information in image processing.

  12. On the origin of pulsing X-ray emission of AE Aqr

    Science.gov (United States)

    Globina, V. I.; Ikhsanov, N. R.

    2017-12-01

    The cataclysmic variable AE Aquarii is a low-mass close binary system containing a red dwarf and a 33 s rotation period magnetic white dwarf which operates as a rotation-powered pulsar. The 33 s pulsations are detected in the optical, UV and X-rays. The 16.5 s harmonic is also present in the optical and UV. This pulsing emission comes from two hot spots (T p ∼ 26000 K) located in the regions of magnetic poles on the white dwarf surface. The nature of the X-ray pulsations of AE Aqr is still under discussion. No 16.5 s harmonic in X-ray is observed and the luminosity of the pulsing component in X-rays is significantly smaller than the luminosity of the pulsing component in the optical and UV. We suggest that the source of pulsing X-ray emission is also located in the magnetic pole region at the surface of the white dwarf and can be associated with a hot spot (T ∼ 106 ‑ 107 K). This spot is heated by the backflowing charged particles. However, the source of particles responsible for the heating the X-ray spot differs from the source of particles responsible for the heating the area emitting in the optical an UV.

  13. Performance of ASTRO-H Hard X-Ray Telescope (HXT)

    Science.gov (United States)

    Awaki, Hisamitsu; Kunieda, Hideyo; Ishida, Manabu; Matsumoto, Hironori; Furuzawa, Akihiro; Haba, Yohsito; Hayashi, Takayuki; Iizuka, Ryo; Ishibashi, Kazunori; Itoh, Masayuki; hide

    2016-01-01

    The Japanese X-ray Astronomy Satellite, Hitomi (ASTRO-H) carries hard X-ray imaging system, covering the energy band from 5 keV to 80 keV. The hard X-ray imaging system consists of two hard X-ray telescopes (HXT) and two hard X-ray imagers (HXI). The HXT employs tightly-nested, conically-approximated thin foil Wolter-I optics. The mirror surfaces of HXT were coated with PtC depth-graded multilayers. We carried out ground calibrations of HXTs at the synchrotron radiation facility SPring-8 BL20B2 in Japan, and found that total effective area of two HXTs was about 350 sq cm at 30 keV, and the half power diameter of HXT was about 1.9. After the launch of Hitomi, Hitomi observed several targets during the initial functional verification of the onboard instruments. The Hitomi software and calibration team (SCT) provided the Hitomis data of G21.5-0.9, a pulsar wind nebula, to the hardware team for the purpose of the instrument calibration. Through the analysis of the in-flight data, we have confirmed that the X-ray performance of HXTs in orbit was consistent with that estimated by the ground calibrations.

  14. Spectral variability of 4U1145-619 during X-ray outburst

    International Nuclear Information System (INIS)

    Cook, M.C.; Warwick, R.S.

    1987-01-01

    A series of observations of the X-ray pulsar 4U1145-619 were performed by EXOSAT during successive X-ray outbursts on this source in 1984 July and 1985 January. On all occasions the source exhibited a very hard power-law X-ray spectrum (photon spectral index approx. 1.0) with a high-energy cut-off above approx. 6 keV. The low-energy cut-off in the X-ray spectrum, in contrast to the other spectral parameters, exhibited significant variations over the observations. Optical spectroscopy of the Be star Hen 715, identified as the optical counterpart of 4U1145-619, was performed during the 1985 January X-ray outburst. The resulting spectra revealed a marked decrease in the strength of the broad blue component of the dominant Hα emission line as the X-ray outburst progressed. There was, however, no evidence for any pulse phase dependency or short-term variability in either the Hα or Hβ emission lines. (author)

  15. Extended hard-X-ray emission in the inner few parsecs of the Galaxy.

    Science.gov (United States)

    Perez, Kerstin; Hailey, Charles J; Bauer, Franz E; Krivonos, Roman A; Mori, Kaya; Baganoff, Frederick K; Barrière, Nicolas M; Boggs, Steven E; Christensen, Finn E; Craig, William W; Grefenstette, Brian W; Grindlay, Jonathan E; Harrison, Fiona A; Hong, Jaesub; Madsen, Kristin K; Nynka, Melania; Stern, Daniel; Tomsick, John A; Wik, Daniel R; Zhang, Shuo; Zhang, William W; Zoglauer, Andreas

    2015-04-30

    The Galactic Centre hosts a puzzling stellar population in its inner few parsecs, with a high abundance of surprisingly young, relatively massive stars bound within the deep potential well of the central supermassive black hole, Sagittarius A* (ref. 1). Previous studies suggest that the population of objects emitting soft X-rays (less than 10 kiloelectronvolts) within the surrounding hundreds of parsecs, as well as the population responsible for unresolved X-ray emission extending along the Galactic plane, is dominated by accreting white dwarf systems. Observations of diffuse hard-X-ray (more than 10 kiloelectronvolts) emission in the inner 10 parsecs, however, have been hampered by the limited spatial resolution of previous instruments. Here we report the presence of a distinct hard-X-ray component within the central 4 × 8 parsecs, as revealed by subarcminute-resolution images in the 20-40 kiloelectronvolt range. This emission is more sharply peaked towards the Galactic Centre than is the surface brightness of the soft-X-ray population. This could indicate a significantly more massive population of accreting white dwarfs, large populations of low-mass X-ray binaries or millisecond pulsars, or particle outflows interacting with the surrounding radiation field, dense molecular material or magnetic fields. However, all these interpretations pose significant challenges to our understanding of stellar evolution, binary formation, and cosmic-ray production in the Galactic Centre.

  16. Precision mechanical structure of an ultra-high-resolution spectrometer for inelastic X-ray scattering instrument

    Science.gov (United States)

    Shu, Deming; Shvydko, Yuri; Stoupin, Stanislav A.; Khachatryan, Ruben; Goetze, Kurt A.; Roberts, Timothy

    2015-04-14

    A method and an ultrahigh-resolution spectrometer including a precision mechanical structure for positioning inelastic X-ray scattering optics are provided. The spectrometer includes an X-ray monochromator and an X-ray analyzer, each including X-ray optics of a collimating (C) crystal, a pair of dispersing (D) element crystals, anomalous transmission filter (F) and a wavelength (W) selector crystal. A respective precision mechanical structure is provided with the X-ray monochromator and the X-ray analyzer. The precision mechanical structure includes a base plate, such as an aluminum base plate; positioning stages for D-crystal alignment; positioning stages with an incline sensor for C/F/W-crystal alignment, and the positioning stages including flexure-based high-stiffness structure.

  17. Ultrashort X-ray pulse science

    Energy Technology Data Exchange (ETDEWEB)

    Chin, Alan Hap [Univ. of California, Berkeley, CA (US). Dept. of Physics; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    1998-05-01

    A variety of phenomena involves atomic motion on the femtosecond time-scale. These phenomena have been studied using ultrashort optical pulses, which indirectly probe atomic positions through changes in optical properties. Because x-rays can more directly probe atomic positions, ultrashort x-ray pulses are better suited for the study of ultrafast structural dynamics. One approach towards generating ultrashort x-ray pulses is by 90° Thomson scattering between terawatt laser pulses and relativistic electrons. Using this technique, the author generated ~ 300 fs, 30 keV (0.4 Å) x-ray pulses. These x-ray pulses are absolutely synchronized with ultrashort laser pulses, allowing femtosecond optical pump/x-ray probe experiments to be performed. Using the right-angle Thomson scattering x-ray source, the author performed time-resolved x-ray diffraction studies of laser-perturbated InSb. These experiments revealed a delayed onset of lattice expansion. This delay is due to the energy relaxation from a dense electron-hole plasma to the lattice. The dense electron-hole plasma first undergoes Auger recombination, which reduces the carrier concentration while maintaining energy content. Longitudinal-optic (LO) phonon emission then couples energy to the lattice. LO phonon decay into acoustic phonons, and acoustic phonon propagation then causes the growth of a thermally expanded layer. Source characterization is instrumental in utilizing ultrashort x-ray pulses in time-resolved x-ray spectroscopies. By measurement of the electron beam diameter at the generation point, the pulse duration of the Thomson scattered x-rays is determined. Analysis of the Thomson scattered x-ray beam properties also provides a novel means of electron bunch characterization. Although the pulse duration is inferred for the Thomson scattering x-ray source, direct measurement is required for other x-ray pulse sources. A method based on the laser-assisted photoelectric effect (LAPE) has been demonstrated as a

  18. Symbiotic Stars in X-rays

    Science.gov (United States)

    Luna, G. J. M.; Sokoloski, J. L.; Mukai, K.; Nelson, T.

    2014-01-01

    Until recently, symbiotic binary systems in which a white dwarf accretes from a red giant were thought to be mainly a soft X-ray population. Here we describe the detection with the X-ray Telescope (XRT) on the Swift satellite of 9 white dwarf symbiotics that were not previously known to be X-ray sources and one that was previously detected as a supersoft X-ray source. The 9 new X-ray detections were the result of a survey of 41 symbiotic stars, and they increase the number of symbiotic stars known to be X-ray sources by approximately 30%. Swift/XRT detected all of the new X-ray sources at energies greater than 2 keV. Their X-ray spectra are consistent with thermal emission and fall naturally into three distinct groups. The first group contains those sources with a single, highly absorbed hard component, which we identify as probably coming from an accretion-disk boundary layer. The second group is composed of those sources with a single, soft X-ray spectral component, which likely arises in a region where low-velocity shocks produce X-ray emission, i.e. a colliding-wind region. The third group consists of those sources with both hard and soft X-ray spectral components. We also find that unlike in the optical, where rapid, stochastic brightness variations from the accretion disk typically are not seen, detectable UV flickering is a common property of symbiotic stars. Supporting our physical interpretation of the two X-ray spectral components, simultaneous Swift UV photometry shows that symbiotic stars with harder X-ray emission tend to have stronger UV flickering, which is usually associated with accretion through a disk. To place these new observations in the context of previous work on X-ray emission from symbiotic stars, we modified and extended the alpha/beta/gamma classification scheme for symbiotic-star X-ray spectra that was introduced by Muerset et al. based upon observations with the ROSAT satellite, to include a new sigma classification for sources with

  19. X-ray fluorescence in geology

    International Nuclear Information System (INIS)

    Dutra, C.V.; Gomes, C.B.

    1990-01-01

    This work is about the X-ray fluorescence aplication in geology. It's showing the X-ray origin and excitation. About the instrumentation this work shows the following: X-ray tubes, colimators, analysers crystals, detectors, amplifiers, pulse height selector, and others electronic components. By X-ray fluorescente are done quantitative and qualitative geological analysis and this work shows this analysis and its detection limits. The problems determination is the example. In this work was done yet the comparative analysis of the various instrumental methods in geochemistry. (C.G.) [pt

  20. X-ray speckle correlation interferometer

    International Nuclear Information System (INIS)

    Eisenhower, Rachel; Materlik, Gerhard

    2000-01-01

    Speckle Pattern Correlation Interferometry (SPCI) is a well-established technique in the visible-light regime for observing surface disturbances. Although not a direct imaging technique, SPCI gives full-field, high-resolution information about an object's motion. Since x-ray synchrotron radiation beamlines with high coherent flux have allowed the observation of x-ray speckle, x-ray SPCI could provide a means to measure strains and other quasi-static motions in disordered systems. This paper therefore examines the feasibility of an x-ray speckle correlation interferometer