WorldWideScience

Sample records for burst x-ray light

  1. A Burst Chasing X-ray Polarimeter

    Science.gov (United States)

    Hill, Joanne

    2007-01-01

    This viewgraph presentation reviews the rationale, design, and importance of an X-Ray Polarimeter. There is a brief discussion of Gamma Ray Bursts, followed by a review of the theories of Gamma-Ray Bursts Polarization. This leads to the question of "How do we measure the polarization?" and a discussion of the GRB x-ray emission, the photoelectric effect and photoelectric polarimetry. The requirements for the work, can only be approached using a gas detector. This leads to a discussion of a Micropattern Gas Polarimeter, and the Time-Projection Chamber (TPC) X-ray Polarimeter.

  2. X-ray bursts observed with JEM-X

    DEFF Research Database (Denmark)

    Brandt, Søren Kristian; Chenevez, Jérôme; Lund, Niels;

    2006-01-01

    We report on the search for X-ray bursts in the JEM-X X-ray monitor on INTEGRAL during the first two years of operations. More than 350 bursts from 25 different type-I X-ray burst sources were found.......We report on the search for X-ray bursts in the JEM-X X-ray monitor on INTEGRAL during the first two years of operations. More than 350 bursts from 25 different type-I X-ray burst sources were found....

  3. Dependence of X-ray Burst Models on Nuclear Masses

    CERN Document Server

    Schatz, H

    2016-01-01

    X-ray burst model predictions of light curves and final composition of the nuclear ashes are affected by uncertain nuclear physics. Nuclear masses play an important role. Significant progress has been made in measuring the masses of very neutron deficient rare isotopes along the path of the rapid proton capture process (rp-process) in X-ray bursts. This paper identifies the remaining nuclear mass uncertainties in X-ray burst models using a one zone model that takes into account the changes in temperature and density evolution caused by changes in the nuclear physics. Two types of bursts are investigated - a typical mixed H/He burst with a limited rp-process and an extreme mixed H/He burst with an extended rp-process. Only three remaining nuclear mass uncertainties affect the light curve predictions of a typical H/He burst, and only three additional masses affect the composition strongly. A larger number of mass uncertainties remains to be addressed for the extreme H/He burst. Mass uncertainties of better than...

  4. Burst Detector X-Ray IIR

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-02-01

    The Burst Detector X-Ray (BDX) instrument for the Block IIR series of Global Positioning System satellites is described. The BDX instrument can locate and characterize exoatmospheric nuclear detonations by using four sensors consisting of sets of filters over silicon diodes to detect x rays of various energies from the burst. On the BDX-IIR, a fifth sensor with a response spanning those of the other sensors confirms coincidences among the four main channels. The mechanical and electronic features of the BDX-IIR and its sensors are described. The calibrations and the system tests used in flight are presented. The commands for the BDX-IIR are given. The messages sent from the BDX-IIR are described in detail.

  5. A Correlation between the Intrinsic Brightness and Average Decay Rate of Gamma-Ray Burst X-Ray Afterglow Light Curves

    Science.gov (United States)

    Racusin, J. L.; Oates, S. R.; de Pasquale, M.; Kocevski, D.

    2016-07-01

    We present a correlation between the average temporal decay ({α }{{X},{avg},\\gt 200{{s}}}) and early-time luminosity ({L}{{X},200{{s}}}) of X-ray afterglows of gamma-ray bursts as observed by the Swift X-ray Telescope. Both quantities are measured relative to a rest-frame time of 200 s after the γ-ray trigger. The luminosity-average decay correlation does not depend on specific temporal behavior and contains one scale-independent quantity minimizing the role of selection effects. This is a complementary correlation to that discovered by Oates et al. in the optical light curves observed by the Swift Ultraviolet Optical Telescope. The correlation indicates that, on average, more luminous X-ray afterglows decay faster than less luminous ones, indicating some relative mechanism for energy dissipation. The X-ray and optical correlations are entirely consistent once corrections are applied and contamination is removed. We explore the possible biases introduced by different light-curve morphologies and observational selection effects, and how either geometrical effects or intrinsic properties of the central engine and jet could explain the observed correlation.

  6. The Extraordinary X-ray Light Curve of the Classical Nova V1494 Aquilae (1999 #2) in Outburst The Discovery of Pulsations and a "Burst"

    CERN Document Server

    Drake, J J; Starrfield, S; Butt, Y; Krautter, J; Bond, H E; Valle, M D; Gehrz, R D; Woodward, C E; Evans, A; Orio, M; Hauschildt, P H; Hernanz, M; Mukai, K; Truran, J W; Drake, Jeremy J.; Starrfield, Sumner; Butt, Yousaf; Krautter, Joachim; Woodward, Charles E.

    2003-01-01

    V1494 Aql (Nova Aql 1999 No. 2) was discovered on 2 December 1999. We obtained Chandra ACIS-I spectra on 15 April and 7 June 2000 which appear to show only emission lines. Our third observation, on 6 August, showed that its spectrum had evolved to that characteristic of a Super Soft X-ray Source. We then obtained Chandra LETG+HRC-S spectra on 28 September (8 ksec) and 1 October (17 ksec). We analyzed the X-ray light curve of our grating observations and found both a short time scale ``burst'' and oscillations. Neither of these phenomena have previously been seen in the light curve of a nova in outburst. The ``burst'' was a factor of 10 rise in X-ray counts near the middle of the second observation, and which lasted about 1000 sec; it exhibited at least two peaks, in addition to other structure. Our time series analysis of the combined 25 ksec observation shows a peak at 2500 s which is present in independent analyses of both the zeroth order image and the dispersed spectrum and is not present in similar analy...

  7. A comprehensive statistical analysis of Swift X-ray light-curves: the prompt-afterglow connection in Gamma-Ray Bursts

    CERN Document Server

    Margutti, Raffaella; Bernardini, M G; Chincarini, G

    2012-01-01

    We present a comprehensive statistical analysis of Swift X-ray light-curves of Gamma-Ray Bursts (GRBs), with more than 650 GRBs. Two questions drive this effort: (1) Does the X-ray emission retain any kind of memory of the prompt phase? (2) Where is the dividing line between long and short GRBs? We show that short GRBs decay faster, are less luminous and less energetic than long GRBs, but are interestingly characterized by very similar intrinsic absorption. Our analysis reveal the existence of a number of relations that link the X-ray to prompt parameters in long GRBs; short GRBs are outliers of the majority of these 2-parameter relations. Here we concentrate on a 3-parameter (E_pk-Egamma,iso-E_X,iso) scaling that is shared by the GRB class as a whole (short GRBs, long GRBs and X-ray Flashes -XRFs): interpreted in terms of emission efficiency, this scaling may imply that GRBs with high $E_{\\rm{pk}}$ are more efficient during their prompt emission.

  8. On the X-Ray emission of Gamma Ray Bursts

    CERN Document Server

    Dado, Shlomo; De Rújula, Alvaro

    2007-01-01

    Recent data gathered and triggered by the SWIFT satellite have greatly improved our knowledge of long-duration gamma ray bursts (GRBs) and X-ray flashes (XRFs). This is particularly the case for the X-ray data at all times. We show that the entire X-ray observations are in excellent agreement with the predictions of the `cannonball' model of GRBs and XRFs, which are based on simple physics and were published long before the launch of SWIFT. Two mechanisms underlie these predictions: inverse Compton scattering and synchrotron radiation, generally dominant at early and late times, respectively. The former mechanism provides a unified description of the gamma-ray peaks, X-ray flares and even the optical `humps' seen in some favourable cases; i.e. their very different durations, fluxes and peak-times are related precisely as predicted. The observed smooth or bumpy fast decay of the X-ray light curve is correctly described case-by-case, in minute detail. The `canonical' X-ray plateau, as well as the subsequent gra...

  9. RXTE detects X-ray bursts from Circinus X-1

    NARCIS (Netherlands)

    Linares, M.; Soleri, P.; Watts, A.; Altamirano, D.; Armas-Padilla, M.; Cavecchi, Y.; Degenaar, N.; Kalamkar, M.; Kaur, R.; van der Klis, M.; Patruno, A.; Wijnands, R.; Yang, Y.; Casella, P.; Rea, N.

    2010-01-01

    After the recent report of X-ray re-brightening (ATel #2608), RXTE has observed the peculiar neutron star X-ray binary Cir X-1 eleven times during the last two weeks (May 11-25, 2010). We report the detection of nine X-ray bursts in RXTE-PCA data, 25 years after the first -and the only previous- det

  10. INTEGRAL monitoring of unusually long X-ray bursts

    DEFF Research Database (Denmark)

    Chenevez, Jérôme; Falanga, M.; Kuulkers, E.;

    2008-01-01

    X-ray bursts are thermonuclear explosions on the surface of accreting neutron stars in X-ray binaries. As most of the known X-ray bursters are frequently observed by INTEGRAL, an international collaboration have been taking advantage of its instrumentation to specifically monitor the occurrence...

  11. Model Atmospheres for X-ray Bursting Neutron Stars

    CERN Document Server

    Medin, Zach; Calder, Alan C; Fontes, Christopher J; Fryer, Chris L; Hungerford, Aimee L

    2016-01-01

    The hydrogen and helium accreted by X-ray bursting neutron stars is periodically consumed in runaway thermonuclear reactions that cause the entire surface to glow brightly in X-rays for a few seconds. With models of the emission, the mass and radius of the neutron star can be inferred from the observations. By simultaneously probing neutron star masses and radii, X-ray bursts are one of the strongest diagnostics of the nature of matter at extremely high densities. Accurate determinations of these parameters are difficult, however, due to the highly non-ideal nature of the atmospheres where X-ray bursts occur. Observations from X-ray telescopes such as RXTE and NuStar can potentially place strong constraints on nuclear matter once uncertainties in atmosphere models have been reduced. Here we discuss current progress on modeling atmospheres of X-ray bursting neutron stars and some of the challenges still to be overcome.

  12. Timing Analysis of the Light Curve of the Dipping-Bursting X-ray Binary X1916-053

    CERN Document Server

    Chou, Y; Bloser, P F

    2001-01-01

    We present the timing analysis results for our observations of the x-ray dip source X1916-053 conducted with RXTE between February and October of 1996. Our goal was to finally measure the binary period - as either the x-ray dip period or ~1% longer optical modulation period, thereby establishing if the binary has a precessing disk (SU UMa model) or a third star (triple model). Combined with historical data (1979-96), the x-ray dip period is measured to be 3000.6508 $\\pm$ 0.0009 sec with a 2$\\sigma$ upper limit $|\\dot P| \\leq 2.06 \\times 10^{-11}$. From our quasi-simultaneous optical observations (May 14-23, 1996) and historical data (1987-96), we measure the optical modulation period to be 3027.5510 $\\pm$ 0.0052 sec with a 2$\\sigma$ upper limit $|\\dot P| \\leq 2.28 \\times 10^{-10}$. The two periods are therefore each stable (over all recorded data) and require a $3.9087 \\pm 0.0008$d beat period. This beat period, and several of its harmonics is also observed as variations in the dip shape. Phase modulation of ...

  13. Uhuru observations of 4U 1608-52 - The 'steady' X-ray source associated with the X-ray burst source in Norma

    Science.gov (United States)

    Tananbaum, H.; Chaisson, L. J.; Forman, W.; Jones, C.; Matilsky, T. A.

    1976-01-01

    Data are presented for the X-ray source 4U 1608-52, summarizing its light curve, location, and spectral parameters. Evidence is presented showing that this source is the 'steady' X-ray counterpart of the X-ray burst source in Norma. The spectrum of the 'steady' source is compared with the spectrum observed during two bursts, and it is noted that there is substantially more low-energy absorption during the bursts. The 'steady' source spectral data are used to examine the optical data, and it is concluded that if the X-ray spectrum is thermal, then a globular-cluster counterpart probably would have been detected (whereas none has been). Further X-ray and optical observations are suggested for this source, since an optical identification may be central in determining whether all X-ray bursts have a common origin and if this origin requires a globular-cluster environment.

  14. Hard X-rays and associated weak decimetric bursts

    Science.gov (United States)

    Sawant, H. S.; Lattari, C. J. B.; Benz, A. O.; Dennis, B. R.

    1990-01-01

    Results are presented of observations (made with the Hard X-Ray Burst Spectrometer on the SMM and with the Itapetinga antenna) that unambiguously show associations of hard X-ray bursts with RS-type III bursts between 16:46 UT and 16:52 UT on July 9, 1985. The comparison between the hard X-ray and the radio observations shows a clear association, in at least 13 cases, of the hard X-ray and the decimetric RS bursts. On the average, the X-ray peaks were delayed from the peak of the RS bursts at 1.6 Ghz by about 400 msec. It is shown that, if the time comparisons are made between the peak of the radio pulse and the start of the X-ray burst, the delays are consistent with an electron travel time with a velocity of about 0.3 c from the 800 MHz plasma level to the lower corona, assuming that the radio emission is at the second harmonic.

  15. Long X-ray burst monitoring with INTEGRAL

    DEFF Research Database (Denmark)

    X-ray bursts are thermonuclear explosions on the surface of accreting neutron stars in low mass X-ray binary systems. In the frame of the INTEGRAL observational Key Programme over the Galactic Center a good number of the known X-ray bursters are frequently being monitored. An international...... collaboration lead by the JEM-X team at the Danish National Space Center has proposed to exploit the improved sensitivity of the INTEGRAL instruments to investigate the observational properties and physics up to high energies of exceptional burst events lasting between a few tens of minutes and several hours...

  16. Controlling X-rays With Light

    Energy Technology Data Exchange (ETDEWEB)

    Glover, Ernie; Hertlein, Marcus; Southworth, Steve; Allison, Tom; van Tilborg, Jeroen; Kanter, Elliot; Krassig, B.; Varma, H.; Rude, Bruce; Santra, Robin; Belkacem, Ali; Young, Linda

    2010-08-02

    Ultrafast x-ray science is an exciting frontier that promises the visualization of electronic, atomic and molecular dynamics on atomic time and length scales. A largelyunexplored area of ultrafast x-ray science is the use of light to control how x-rays interact with matter. In order to extend control concepts established for long wavelengthprobes to the x-ray regime, the optical control field must drive a coherent electronic response on a timescale comparable to femtosecond core-hole lifetimes. An intense field is required to achieve this rapid response. Here an intense optical control pulse isobserved to efficiently modulate photoelectric absorption for x-rays and to create an ultrafast transparency window. We demonstrate an application of x-ray transparencyrelevant to ultrafast x-ray sources: an all-photonic temporal cross-correlation measurement of a femtosecond x-ray pulse. The ability to control x-ray/matterinteractions with light will create new opportunities at current and next-generation x-ray light sources.

  17. The INTEGRAL view of intermediate long X-ray bursts

    DEFF Research Database (Denmark)

    CONCLUSIONS Most intermediate bursts are observed from low luminosity sources and are interpreted as long pure He bursts. If no H is accreted, they are consistent with the burning of a slowly accreted, thick He layer, in Ultra Compact X-ray Binaries (UCXB) where the donor star is probably a degen...

  18. Magnetar-like X-ray bursts from an anomalous X-ray pulsar.

    Science.gov (United States)

    Gavriil, F P; Kaspi, V M; Woods, P M

    2002-09-12

    Anomalous X-ray pulsars (AXPs) are a class of rare X-ray emitting pulsars whose energy source has been perplexing for some 20 years. Unlike other X-ray emitting pulsars, AXPs cannot be powered by rotational energy or by accretion of matter from a binary companion star, hence the designation 'anomalous'. Many of the rotational and radiative properties of the AXPs are strikingly similar to those of another class of exotic objects, the soft-gamma-ray repeaters (SGRs). But the defining property of the SGRs--their low-energy-gamma-ray and X-ray bursts--has not hitherto been observed for AXPs. Soft-gamma-ray repeaters are thought to be 'magnetars', which are young neutron stars whose emission is powered by the decay of an ultra-high magnetic field; the suggestion that AXPs might also be magnetars has been controversial. Here we report two X-ray bursts, with properties similar to those of SGRs, from the direction of the anomalous X-ray pulsar 1E1048.1 - 5937. These events imply a close relationship (perhaps evolutionary) between AXPs and SGRs, with both being magnetars.

  19. MAXI observations of long X-ray bursts

    Science.gov (United States)

    Serino, Motoko; Iwakiri, Wataru; Tamagawa, Toru; Sakamoto, Takanori; Nakahira, Satoshi; Matsuoka, Masaru; Yamaoka, Kazutaka; Negoro, Hitoshi

    2016-12-01

    We report nine long X-ray bursts from neutron stars, detected with the Monitor of All-sky X-ray Image (MAXI). Some of these bursts lasted for hours, and hence are qualified as superbursts, which are prolonged thermonuclear flashes on neutron stars and are relatively rare events. MAXI observes roughly 85% of the whole sky every 92 minutes in the 2-20 keV energy band, and has detected nine bursts with a long e-folding decay time, ranging from 0.27 to 5.2 hr, since its launch in 2009 August until 2015 August. The majority of the nine events were found to originate from transient X-ray sources. The persistent luminosities of the sources, when these prolonged bursts were observed, were lower than 1% of the Eddington luminosity for five of them and lower than 20% for the rest. This trend is contrastive to the 18 superbursts observed before MAXI, all but two of which originated from bright persistent sources. The distribution of the total emitted energy, i.e., the product of e-folding time and luminosity, of these bursts clusters around 1041-1042 erg, whereas both the e-folding time and luminosity ranges for an order of magnitude. Among the nine events, two were from 4U 1850-086 during phases of relatively low persistent flux, whereas it usually exhibits standard short X-ray bursts during outbursts.

  20. K alpha line emission during solar X-ray bursts

    Science.gov (United States)

    Phillips, K. J. H.; Neupert, W. M.

    1973-01-01

    The expected flux of K alpha line emission from sulfur, argon, calcium, and iron is calculated during both thermal and nonthermal solar X-ray events. Such emission is shown to be weak during the course of most of the nonthermal hard X-ray bursts that Kane and Anderson (1970) have observed. If Compton backscattering is significant at high energies, the flux is reduced still further for disk flares, but it is noted that the strong, near-limb burst of June 26 would have produced about 100 photons /sq cm/sec of sulfur and iron K alpha emission. The impulsive hard X-ray bursts may in general be too short-lived for much K alpha emission. It may be noted that sulfur K alpha emission in particular depends sensitively on the lower-energy limit of the nonthermal electron spectrum, assuming such a sharply defined boundary exists. During soft X-ray bursts, when temperatures of a few 10 to the 7th power K are obtained, K alpha emission from certain iron ions, specifically Fe XVIII-XXIII, may be important.

  1. INTEGRAL monitoring of unusually long X-ray bursts

    DEFF Research Database (Denmark)

    of the known X-ray bursters are frequently observed by INTEGRAL, in particular in the frame of the Key Programmes. Taking advantage of the INTEGRAL instrumentation, an international collaboration led by the JEM-X team at the Danish National Space Institute has been monitoring the occurrence of uncommon burst...

  2. An accretion disk swept up by a powerful thermonuclear X-ray burst

    Science.gov (United States)

    Degenaar, Nathalie

    Type-I X-ray bursts are thermonuclear explosions occurring in the surface layers of accreting neutron stars. These events are powerful probes of the physics of neutron stars and their surrounding accretion flow. Swift recently caught a very energetic type-I X-ray burst from the neutron star IGR J17062-6143 that displayed exceptional features. Firstly, the light curve of the 18 minute long X-ray burst tail shows an episode of 10 minutes with wild X-ray intensity fluctuations. Secondly, X-ray spectral analysis revealed a highly significant emission line around 1 keV, which can be interpreted as an Fe-L shell line caused by the irradiation of cold gas. Finally, the detection of significant absorption lines and edges in the Fe-K band are strongly suggestive of the presence of hot, highly ionized gas along the line of sight. None of these features are present in the persistent emission of the source. The X-ray burst of IGR J17062-6143 shows the first unambiguous detection of atomic features at CCD resolution. The timescale of the strong intensity variations, the velocity width of the Fe-L emission line, and photo-ionization modeling of the Fe-K absorption features each independently point to swept-up gas at a radius of ~1000 km from the neutron star. The unusual X-ray light curve and spectral properties could have plausibly been caused by a disruption of the accretion disk due to the super-Eddington fluxes reached during the X-ray burst.

  3. Understanding Neutron Stars using Thermonuclear X-ray Bursts

    Science.gov (United States)

    Bhattacharyya, S.

    2007-01-01

    Studies of thermonuclear X-ray bursts can be very useful to constrain the spin rate, mass and radius of a neutron star = EOS model of high density cold matter in the neutron star cores. Extensive observation and analysis of the data from the rising portions of the bursts = modeling of burst oscillations and thermonuclear flame spreading. Theoretical study of thermonuclear flame spreading on the rapidly spinning neutron stars should be done considering all the main physical effects (including magnetic field, nuclear energy generation, Coriolis effect, strong gravity, etc.).

  4. Neutron Stars and Thermonuclear X-ray Bursts

    Science.gov (United States)

    Bhattacharyya, Sudip

    2007-01-01

    Studies of thermonuclear X-ray bursts can be very useful to constrain the spin rate, mass and radius of a neutron star approaching EOS model of high density cold matter in the neutron star cores. +k Extensive observation and analysis of the data from the rising portions of the bursts - modeling of burst oscillations and thermonuclear flame spreading. +k Theoretical study of thermonuclear flame spreading on the rapidly spinning neutron stars should be done considering all the main physical effects (including magnetic field, nuclear energy generation, Coriolis effect, strong gravity, etc.).

  5. Dependence of X-Ray Burst Models on Nuclear Reaction Rates

    Science.gov (United States)

    Cyburt, R. H.; Amthor, A. M.; Heger, A.; Johnson, E.; Keek, L.; Meisel, Z.; Schatz, H.; Smith, K.

    2016-10-01

    X-ray bursts are thermonuclear flashes on the surface of accreting neutron stars, and reliable burst models are needed to interpret observations in terms of properties of the neutron star and the binary system. We investigate the dependence of X-ray burst models on uncertainties in (p, γ), (α, γ), and (α, p) nuclear reaction rates using fully self-consistent burst models that account for the feedbacks between changes in nuclear energy generation and changes in astrophysical conditions. A two-step approach first identified sensitive nuclear reaction rates in a single-zone model with ignition conditions chosen to match calculations with a state-of-the-art 1D multi-zone model based on the Kepler stellar evolution code. All relevant reaction rates on neutron-deficient isotopes up to mass 106 were individually varied by a factor of 100 up and down. Calculations of the 84 changes in reaction rate with the highest impact were then repeated in the 1D multi-zone model. We find a number of uncertain reaction rates that affect predictions of light curves and burst ashes significantly. The results provide insights into the nuclear processes that shape observables from X-ray bursts, and guidance for future nuclear physics work to reduce nuclear uncertainties in X-ray burst models.

  6. Echo Emission From Dust Scattering and X-Ray Afterglows of Gamma-Ray Bursts

    CERN Document Server

    Shao, L; Mirabal, N

    2007-01-01

    We investigate the effect of X-ray echo emission in gamma-ray bursts (GRBs). We find that the echo emission can provide an alternative way of understanding X-ray shallow decays and jet breaks. In particular, a shallow decay followed by a "normal" decay and a further rapid decay of X-ray afterglows can be together explained as being due to the echo from prompt X-ray emission scattered by dust grains in a massive wind bubble around a GRB progenitor. We also introduce an extra temporal break in the X-ray echo emission. By fitting the afterglow light curves, we can measure the locations of the massive wind bubbles, which will bring us closer to finding the mass loss rate, wind velocity, and the age of the progenitors prior to the GRB explosions.

  7. X-ray bursts and superbursts - recent developments

    CERN Document Server

    Zand, Jean in 't

    2011-01-01

    The past decade and a half has seen many interesting new developments in X-ray burst research, both observationally and theoretically. New phenomena were discovered, such as burst oscillations and superbursts, and new regimes of thermonuclear burning identified. An important driver of the research with present and future instrumentation in the coming years is the pursuit of fundamental neutron star parameters. However, several other more direct questions are also in dire need of an answer. For instance, how are superbursts ignited and why do burst oscillations exist in burst tails? We briefly review recent developments and discuss the role that MAXI can play. Thanks to MAXI's large visibility window and large duty cycle, it is particularly well suited to investigate the recurrence of rare long duration bursts such as superbursts. An exploratory study of MAXI data is briefly presented.

  8. Maxi observations of long X-ray bursts

    CERN Document Server

    Serino, Motoko; Tamagawa, Toru; Sakamoto, Takanori; Nakahira, Satoshi; Matsuoka, Masaru; Yamaoka, Kazutaka; Negoro, Hitoshi

    2016-01-01

    We report nine long X-ray bursts from neutron stars, detected with Monitor of All-sky X-ray Image (MAXI). Some of these bursts lasted for hours, and hence are qualified as superbursts, which are prolonged thermonuclear flashes on neutron stars and are relatively rare events. MAXI observes roughly 85% of the whole sky every 92 minutes in the 2-20 keV energy band, and has detected nine bursts with a long e-folding decay time, ranging from 0.27 to 5.2 hours, since its launch in 2009 August until 2015 August. The majority of the nine events were found to originate from transient X-ray sources. The persistent luminosities of the sources, when these prolonged bursts were observed, were lower than 1% of the Eddington luminosity for five of them and lower than 20% for the rest. This trend is contrastive to the 18 superbursts observed before MAXI, all but two of which originated from bright persistent sources. The distribution of the total emitted energy, i.e., the product of e-folding time and luminosity, of these bu...

  9. Future Probes of the Neutron Star Equation of State Using X-ray Bursts

    OpenAIRE

    Strohmayer, Tod E.

    2004-01-01

    Observations with NASA's Rossi X-ray Timing Explorer (RXTE) have resulted in the discovery of fast (200 - 600 Hz), coherent X-ray intensity oscillations (hereafter, "burst oscillations") during thermonuclear X-ray bursts from 12 low mass X-ray binaries (LMXBs). It is now beyond doubt that these oscillations result from spin modulation of the thermonuclear burst flux from the neutron star surface. Among the new timing phenomena revealed by RXTE the burst oscillations are perhaps the best under...

  10. Detection of burning ashes from thermonuclear X-ray bursts

    Science.gov (United States)

    Kajava, J. J. E.; Nättilä, J.; Poutanen, J.; Cumming, A.; Suleimanov, V.; Kuulkers, E.

    2017-01-01

    When neutron stars (NS) accrete gas from low-mass binary companions, explosive nuclear burning reactions in the NS envelope fuse hydrogen and helium into heavier elements. The resulting thermonuclear (type-I) X-ray bursts produce energy spectra that are fit well with black bodies, but a significant number of burst observations show deviations from Planck spectra. Here we present our analysis of RXTE/PCA observations of X-ray bursts from the NS low-mass X-ray binary HETE J1900.1-2455. We have discovered that the non-Planckian spectra are caused by photoionization edges. The anticorrelation between the strength of the edges and the colour temperature suggests that the edges are produced by the nuclear burning ashes that have been transported upwards by convection and become exposed at the photosphere. The atmosphere model fits show that occasionally the photosphere can consist entirely of metals, and that the peculiar changes in blackbody temperature and radius can be attributed to the emergence and disappearance of metals in the photosphere. As the metals are detected already in the Eddington-limited phase, it is possible that a radiatively driven wind ejects some of the burning ashes into the interstellar space.

  11. Detection of burning ashes from thermonuclear X-ray bursts

    CERN Document Server

    Kajava, J J E; Poutanen, J; Cumming, A; Suleimanov, V; Kuulkers, E

    2016-01-01

    When neutron stars (NS) accrete gas from low-mass binary companions, explosive nuclear burning reactions in the NS envelope fuse hydrogen and helium into heavier elements. The resulting thermonuclear (type-I) X-ray bursts produce energy spectra that are fit well with black bodies, but a significant number of burst observations show deviations from Planck spectra. Here we present our analysis of RXTE/PCA observations of X-ray bursts from the NS low-mass X-ray binary HETE J1900.1-2455. We have discovered that the non-Planckian spectra are caused by photo-ionization edges. The anti-correlation between the strength of the edges and the colour temperature suggests that the edges are produced by the nuclear burning ashes that have been transported upwards by convection and become exposed at the photosphere. The atmosphere model fits show that occasionally the photosphere can consist entirely of metals, and that the peculiar changes in black body temperature and radius can be attributed to the emergence and disappea...

  12. X-ray Burst Oscillations: From Flame Spreading to the Cooling Wake

    CERN Document Server

    Mahmoodifar, Simin

    2015-01-01

    Type I X-ray bursts are thermonuclear flashes observed from the surface of accreting neutron stars in Low Mass X-ray Binaries. Oscillations have been observed during the rise and/or decay of some of these X-ray bursts. Those seen during the rise can be well explained by a spreading hot spot model, but to date there haven't been any quantitative studies that consistently track the oscillation amplitude both during the rise and decay (tail) of bursts. Here we compute the light curves and amplitudes of oscillations in X-ray burst models that realistically account for both flame spreading and subsequent cooling. We present results for two such "cooling wake" models, a "canonical" cooling model where each patch on the neutron star surface heats and cools identically, and an "asymmetric" model where parts of the star cool at different rates. We show that while canonical cooling models can generate oscillations in the tails of bursts, they cannot easily produce the highest observed modulation amplitudes. Alternative...

  13. Sensitivity of Type I X-Ray Bursts to rp-Process Reaction Rates

    CERN Document Server

    Amthor, A M; Heger, A; Sakharuk, A; Schatz, H; Smith, K; Galaviz, Daniel; Heger, Alexander; Sakharuk, Alexander; Schatz, Hendrik; Smith, Karl

    2006-01-01

    First steps have been taken in a more comprehensive study of the dependence of observables in Type I X-ray bursts on uncertain (p,gamma) reaction rates along the rp-process path. We use the multizone hydrodynamics code KEPLER which implicitly couples a full nuclear reaction network of more than 1000 isotopes, as needed, to follow structure and evolution of the X-ray burst layer and its ashes. This allows us to incorporate the full rp-process network, including all relevant nuclear reactions, and individually study changes in the X-ray burst light curves when modifying selected key nuclear reaction rates. In this work we considered all possible proton captures to nuclei with 10 < Z < 28 and N <= Z. When varying individual reaction rates within a symmetric full width uncertainty of a factor of 10000, early results for some rates show changes in the burst light curve as large as 10 percent of peak luminosity. This is very large compared to the current sensitivity of X-ray observations. More precise reac...

  14. X-RAY EMISSION AND ABSORPTION FEATURES DURING AN ENERGETIC THERMONUCLEAR X-RAY BURST FROM IGR J17062-6143

    Energy Technology Data Exchange (ETDEWEB)

    Degenaar, N.; Miller, J. M. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Wijnands, R.; Altamirano, D. [Astronomical Institute ' ' Anton Pannekoek' ' , University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands); Fabian, A. C., E-mail: degenaar@umich.edu [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 OHA (United Kingdom)

    2013-04-20

    Type-I X-ray bursts are thermonuclear explosions occurring in the surface layers of accreting neutron stars. These events are powerful probes of the physics of neutron stars and their surrounding accretion flow. We analyze a very energetic type-I X-ray burst from the neutron star low-mass X-ray binary IGR J17062-6143 that was detected with Swift on 2012 June 25. The light curve of the {approx_equal}18 minute long X-ray burst tail shows an episode of {approx_equal}10 minutes during which the intensity is strongly fluctuating by a factor of {approx_equal}3 above and below the underlying decay trend on a timescale of seconds. The X-ray spectrum reveals a highly significant emission line around {approx_equal}1 keV, which can be interpreted as an Fe-L shell line caused by the irradiation of cold gas. We also detect significant absorption lines and edges in the Fe-K band, which are strongly suggestive of the presence of hot, highly ionized gas along the line of sight. None of these features are present in the persistent X-ray spectrum of the source. The timescale of the strong intensity variations, the velocity width of the Fe-L emission line (assuming Keplerian motion), and photoionization modeling of the Fe-K absorption features each independently point to gas at a radius of {approx_equal} 10{sup 3} km as the source of these features. The unusual X-ray light curve and spectral properties could have plausibly been caused by a disruption of the accretion disk due to the super-Eddington fluxes reached during the X-ray burst.

  15. X-ray emission and absorption features during an energetic thermonuclear X-ray burst from IGR J17062-6143

    CERN Document Server

    Degenaar, N; Wijnands, R; Altamirano, D; Fabian, A C

    2012-01-01

    Type-I X-ray bursts are thermonuclear explosions occurring in the surface layers of accreting neutron stars. These events are powerful probes of the physics of neutron stars and their surrounding accretion flow. We analyze a very energetic type-I X-ray burst from the neutron star low-mass X-ray binary IGR J17062-6143 that was detected with Swift on 2012 June 25. The light curve of the ~18 min long X-ray burst tail shows an episode of ~10 min during which the intensity is strongly fluctuating by a factor of ~3 above and below the underlying decay trend, on a time scale of seconds. The X-ray spectrum reveals a highly significant emission line around ~1 keV, which can be interpreted as a Fe-L shell line caused by irradiation of cold gas. We also detect significant absorption lines and edges in the Fe-K band, which are strongly suggestive of the presence of hot, highly ionized gas along the line of sight. None of these features are present in the persistent X-ray spectrum of the source. The time scale of the stro...

  16. Computational Models of X-Ray Burst Quenching Times and 12C Nucleosynthesis Following a Superburst

    Energy Technology Data Exchange (ETDEWEB)

    Fisker, J L

    2009-03-19

    Superbursts are energetic events on neutron stars that are a thousand times more powerful than ordinary type I X-ray bursts. They are believed to be powered by a thermonuclear explosion of accumulated {sup 12}C. However, the source of this {sup 12}C remains elusive to theoretical calculations and its concentration and ignition depth are both unknown. Here we present the first computational simulations of the nucleosynthesis during the thermal decay of a superbust, where X-ray bursts are quenched. Our calculations of the quenching time verify previous analytical calculations and shed new light on the physics of stable burning at low accretion rates. We show that concentrated (X{sub {sup 12}C} {approx}> 0.40), although insufficient, amounts of {sup 12}C are generated during the several weeks following the superburst where the decaying thermal flux of the superburst stabilizes the burning of the accreted material.

  17. Modeling Gamma-Ray Burst X-Ray Flares within the Internal Shock Model

    CERN Document Server

    Maxham, Amanda

    2009-01-01

    X-ray afterglow light curves have been collected for over 400 Swift gamma-ray bursts with nearly half of them having X-ray flares superimposed on the regular afterglow decay. Evidence suggests that gamma-ray prompt emission and X-ray flares share a common origin and that at least some flares can only be explained by long-lasting central engine activity. We have developed a shell model code to address the question of how X-ray flares are produced within the framework of the internal shock model. The shell model creates randomized GRB explosions from a central engine with multiple shells and follows those shells as they collide, merge and spread, producing prompt emission and X-ray flares. We pay special attention to the time history of central engine activity, internal shocks, and observed flares, but do not calculate the shock dynamics and radiation processes in detail. Using the empirical E_p - E_iso (Amati) relation with an assumed Band function spectrum for each collision and an empirical flare temporal pr...

  18. Swift-XRT detects X-ray burst from Circinus X-1

    NARCIS (Netherlands)

    Linares, M.; Soleri, P.; Altamirano, D.; Armas-Padilla, M.; Cavecchi, Y.; Degenaar, N.; Kalamkar, M.; Kaur, R.; van der Klis, M.; Patruno, A.; Watts, A.; Wijnands, R.; Yang, Y.; Casella, P.; Rea, N.; Chakrabarty, D.; Homan, J.

    2010-01-01

    Following the recent re-brightening (ATel #2608) and RXTE-PCA detection of X-ray bursts from the peculiar X-ray binary Cir X-1 between May 15 and 25 (ATel #2643), we obtained a series of Swift-XRT observations of the field (see also ATel #2650). Swift-XRT detected an X-ray burst on 2010-05-28 at 12:

  19. Modeling Gamma-Ray Burst X-Ray Flares Within the Internal Shock Model

    Science.gov (United States)

    Maxham, Amanda; Zhang, Bing

    2009-12-01

    X-ray afterglow light curves have been collected for over 400 Swift gamma-ray bursts (GRBs) with nearly half of them having X-ray flares superimposed on the regular afterglow decay. Evidence suggests that gamma-ray prompt emission and X-ray flares share a common origin and that at least some flares can only be explained by long-lasting central engine activity. We have developed a shell model code to address the question of how X-ray flares are produced within the framework of the internal shock model. The shell model creates randomized GRB explosions from a central engine with multiple shells and follows those shells as they collide, merge, and spread, producing prompt emission and X-ray flares. We pay special attention to the time history of central engine activity, internal shocks, and observed flares, but do not calculate the shock dynamics and radiation processes in detail. Using the empirical Ep -E iso (Amati) relation with an assumed Band function spectrum for each collision and an empirical flare temporal profile, we calculate the gamma-ray (Swift/BAT band) and X-ray (Swift/XRT band) lightcurves for arbitrary central engine activity and compare the model results with the observational data. We show that the observed X-ray flare phenomenology can be explained within the internal shock model. The number, width, and occurring time of flares are then used to diagnose the central engine activity, putting constraints on the energy, ejection time, width, and number of ejected shells. We find that the observed X-ray flare time history generally reflects the time history of the central engine, which reactivates multiple times after the prompt emission phase with progressively reduced energy. The same shell model predicts an external shock X-ray afterglow component, which has a shallow decay phase due to the initial pile-up of shells onto the blast wave. However, the predicted X-ray afterglow is too bright as compared with the observed flux level, unless epsilon e is

  20. Burst-only sources: probing type I X-ray bursters at low persistent luminosities

    Energy Technology Data Exchange (ETDEWEB)

    Cornelisse, R.; Zand, J.J.M. in ' t; Kuulkers, E.; Heise, J.; Verbunt, F.; Cocchi, M.; Bazzano, A.; Natalucci, L.; Ubertini, P

    2004-06-01

    The Wide Field Cameras onboard BeppoSAX observed 9 type I X-ray bursters without detectable persistent emission around the burst. According to the standard theory of X-ray bursts these sources should be in the lowest mass-accretion regime, opening the possibility to study this regime for the first time. We compare the sources with the burst theory, and show that the evidence of a new sub-class of low mass X-ray binaries, the burst-only source, is still meagre.

  1. X-ray burst-induced spectral variability in 4U 1728-34

    Science.gov (United States)

    Kajava, J. J. E.; Sánchez-Fernández, C.; Kuulkers, E.; Poutanen, J.

    2017-03-01

    Aims: INTEGRAL has been monitoring the Galactic center region for more than a decade. Over this time it has detected hundreds of type-I X-ray bursts from the neutron star low-mass X-ray binary 4U 1728-34, also known as the slow burster. Our aim is to study the connection between the persistent X-ray spectra and the X-ray burst spectra in a broad spectral range. Methods: We performed spectral modeling of the persistent emission and the X-ray burst emission of 4U 1728-34 using data from the INTEGRAL JEM-X and IBIS/ISGRI instruments. Results: We constructed a hardness intensity diagram to track spectral state variations. In the soft state, the energy spectra are characterized by two thermal components likely coming from the accretion disc and the boundary/spreading layer, together with a weak hard X-ray tail that we detect in 4U 1728-34 for the first time in the 40 to 80 keV range. In the hard state, the source is detected up to 200 keV and the spectrum can be described by a thermal Comptonization model plus an additional component: either a powerlaw tail or reflection. By stacking 123 X-ray bursts in the hard state, we detect emission up to 80 keV during the X-ray bursts. We find that during the bursts the emission above 40 keV decreases by a factor of approximately three with respect to the persistent emission level. Conclusions: Our results suggest that the enhanced X-ray burst emission changes the spectral properties of the accretion disc in the hard state. The likely cause is an X-ray burst induced cooling of the electrons in the inner hot flow near the neutron star.

  2. Se-68 rp-process waiting point and X-ray bursts

    Science.gov (United States)

    Del Santo, M.; Schatz, H.; Lorusso, G.; Crawford, H.; Grinyer, G. F.; Meisel, Z.; Becerril, A.; Montes, F.; Pereira, J.; Smith, K.; George, S.; Bazin, D.; Mantica, P.

    2011-04-01

    The x-ray light curve of astrophysical X-ray bursts and the composition of their nuclear ashes are shaped by the effective half-life of Se-68, a rare neutron deficient isotope near the proton drip line and a waiting point in the rapid proton capture process (rp-process). We addressed the nuclear physics uncertainty in the Se-68 half-life by studying the beta-delayed particle emission of Kr-69. The experiment was performed at the National Superconducting Cyclotron Laboratory (NSCL). The rare isotope beam was produced by fragmentation of a Kr-78 primary beam, separated using the A1900 and Radio Frequency Fragment Separator, and sent to the Beta Counting Station (BCS). The remaining fragments were implanted into a 500 micron double-sided-Si-strip-detector (DSSD) to detect charged particles (fast electrons and protons) following beta decay. The measured decay curve and delayed proton spectrum will be presented and the possible implications on the energy production in X-ray bursts and mass flow along the rp-process path in the A ~ 70 region will be discussed. This work was supported in part by the National Science Foundation.

  3. X-Ray Bursts from the Transient Magnetar Candidate XTE J1810-197

    Science.gov (United States)

    Kouveliotou, Chryssa; Woods, Peter M.; Gavriil, Fotis P.; Kaspi, Victoria M.; Roberts, Mallory S. E.; Ibrahim, Alaa; Markwardt, Craig B.; Swank, Jean H.; Finger, Mark H.

    2005-01-01

    We have discovered four X-ray bursts, recorded with the Rossi X-ray Timing Explorer Proportional Counter Array between 2003 September and 2004 April, that we show to originate from the transient magnetar candidate XTE 51810-197. The burst morphologies consist of a short spike or multiple spikes lasting approx. 1 s each followed by extended tails of emission where the pulsed flux from XTE 51810-197 is significantly higher. The burst spikes are likely correlated with the pulse maxima, having a chance probability of a random phase distribution of 0.4%. The burst spectra are best fit to a blackbody with temperatures 4-8 keV, considerably harder than the persistent X-ray emission. During the X-ray tails following these bursts, the temperature rapidly cools as the flux declines, maintaining a constant emitting radius after the initial burst peak. The temporal and spectral characteristics of these bursts closely resemble the bursts seen from 1E 1048.1-5937 and a subset of the bursts detected from 1E 2259+586, thus establishing XTE J1810-197 as a magnetar candidate. The bursts detected from these three objects are sufficiently similar to one another, yet si,g&cantly differe2t from those seen from soft gamma repeaters, that they likely represent a new class of bursts from magnetar candidates exclusive (thus far) to the anomalous X-ray pulsar-like sources.

  4. Coronal type III radio bursts and their X-ray flare and interplanetary type III counterparts

    CERN Document Server

    Reid, Hamish A S

    2016-01-01

    Type III bursts and hard X-rays are both produced by flare energetic electron beams. The link between both emissions has been investigated in many previous studies, but no statistical studies have compared both coronal and interplanetary type III bursts with X-ray flares. Using coronal radio events above 100 MHz exclusively from type III bursts, we revisited long-standing questions: Do all coronal type III bursts have X-ray counterparts. What correlation, if any, occurs between radio and X-ray intensities. What X-ray and radio signatures above 100 MHz occur in connection with interplanetary type III bursts below 14 MHz. We analysed data from 2002 to 2011 starting with coronal type III bursts above 100 MHz. We used RHESSI X-ray data greater than 6 keV to make a list of 321 events that have associated type III bursts and X-ray flares, encompassing at least 28 percent of the initial sample of type III events. We examined the timings, intensities, associated GOES class, and any interplanetary radio signature. For...

  5. The Microchannel X-ray Telescope for the Gamma-Ray Burst mission SVOM

    CERN Document Server

    Gotz, D; Cordier, B; Paul, J; Evans, P; Beardmore, A; Martindale, A; Willingale, R; O'Brien, P; Basa, S; Rossin, C; Godet, O; Webb, N; Greiner, J; Nandra, K; Meidinger, N; Perinati, E; Santangelo, A; Mercier, K; Gonzalez, F

    2014-01-01

    We present the Microchannel X-ray Telescope, a new light and compact focussing telescope that will be flying on the Sino-French SVOM mission dedicated to Gamma-Ray Burst science. The MXT design is based on the coupling of square pore micro-channel plates with a low noise pnCCD. MXT will provide an effective area of about 50 cmsq, and its point spread function is expected to be better than 3.7 arc min (FWHM) on axis. The estimated sensitivity is adequate to detect all the afterglows of the SVOM GRBs, and to localize them to better then 60 arc sec after five minutes of observation.

  6. Discovery of hard X-ray emission from Type II bursts of the Rapid Burster

    CERN Document Server

    Frontera, F; Orlandini, M; Amati, L; Palazzi, E; Dal Fiume, D; Del Sordo, S; Cusumano, G; Parmar, A N; Pareschi, G; Lapidus, I; Stella, L

    2000-01-01

    We report on results of BeppoSAX Target Of Opportunity (TOO) observations of the source MXB 1730-335, also called the Rapid Burster (RB), made during its outburst of February-March 1998. We monitored the evolution of the spectral properties of the RB from the outburst decay to quiescence. During the first TOO, the X-ray light curve of the RB showed many Type II bursts and its broadband (1-100 keV) spectrum was acceptably fit with a two blackbody plus power law model. Moreover, to our knowledge, this is the first time that this source is detected beyond 30 keV.

  7. Puzzling thermonuclear burst behaviour from the transient low-mass X-ray binary IGR J17473-2721

    DEFF Research Database (Denmark)

    Chenevez, Jérôme; Altamirano, Diego; Galloway, Duncan

    2010-01-01

    We investigate the thermonuclear bursting behaviour of IGR J17473−2721, an X-ray transient that in 2008 underwent a 6-month long outburst, starting (unusually) with an X-ray burst. We detected a total of 57 thermonuclear bursts throughout the outburst with AGILE, Swift, Rossi X-ray Timing Explore...

  8. Search for Millisecond Periodicities in Type I X-ray Bursts of the Rapid Burster

    CERN Document Server

    Fox, D W; Rutledge, R E; Morgan, E H; Guerriero, R A; Bildsten, L; Van der Klis, M; Van Paradijs, J; Moore, C B; Dotani, T; Asai, K

    2000-01-01

    We have searched the rising portion of type I X-ray bursts observed from the Rapid Burster with the Rossi X-ray Timing Explorer for the presence of periodicities. The 95 per cent confidence upper limit on the average root-mean-square variation of near coherent pulsations with a width of 98 per cent significance) at 306.5 Hz.

  9. The hard X-ray shortages prompted by the clock bursts in GS 1826--238

    CERN Document Server

    Long, Ji; YuPeng, Chen; Shuang-Nan, Zhang; Diego, Torres F; Peter, Kretschmar; Jian, Li

    2013-01-01

    We report on a study of GS 1826--238 using all available {\\it RXTE} observations, concentrating on the behavior of the hard X-rays during type-I bursts. We find a hard X-ray shortage at 30--50 keV promoted by the shower of soft X-rays coming from type-I bursts. This shortage happens with a time delay after the peak of the soft flux of 3.6 $\\pm$ 1.2 seconds.The behavior of hard X-rays during bursts indicates cooling and reheating of the corona, during which a large amount of energy is required. We speculate that this energy originates from the feedback of the type-I bursts to the accretion process, resulting in a rapid temporary increase of the accretion rate.

  10. Observations of Type i X-Ray Bursts from GS 1826-238 with RXTE

    Science.gov (United States)

    Lewin, Walter

    Type I X-ray bursts are the result of thermonuclear flashes on the surface of accreting neutron stars. The spectral lines which are expected in the X-ray spectra of the bursts will allow for a direct measurement of the gravitational redshift from the surface of the neutron stars (one of the holy grails in physics). XMM-Newton has the potential of detecting such lines. We have been awarded 200 ksec observations with XMM-Newton of the X-ray burster GS 1826-238. During this time we expect to observe ten X-ray bursts and to accumulate about 40,000 high-spectral resolution burst counts with the RGS, and roughly 2 Mcounts with EPIC-PN. We are requesting simultaneous observations with RXTE to obtain essential information about the underlying continuum spectrum.

  11. Modification of gravitational redshift of x-ray burst produced by pulsar surface magnetoplasma

    Institute of Scientific and Technical Information of China (English)

    Zhu Jun; Ji Pei-Yong

    2008-01-01

    In this paper,the propagation of x-ray bursts in the magnetoplasma of pulsar magnetosphere is discussed.The electromagnetic interaction between x-ray bursts and magnetoplasma is described as some geometry.The electromagnetic effects of surface superstrong magnetic field and dynamic effects of outflowing magnetoplasma of pulsars are treated as an optical metric.The Gordon metric is introduced to represent the gravitational metric and optical metric.So the propagation of x-ray bursts in magnetoplasma of pulsars can be described as x-ray bursts transmitting in an effective space characterized by Gordon metric.The modification of gravitational redshift,attributed to the flowing magnetoplasma of pulsars,is obtained and it is shown that the modification is of redshift and can reach the same magnitude as the gravitational redshift for ordinary pulsars.

  12. X-ray bursts at extreme mass accretion rates from GX 17+2

    CERN Document Server

    Kuulkers, E; Van der Klis, M; Lewin, W H G; Méndez, M

    2002-01-01

    (abridged version) We report on ten X-ray bursts from GX 17+2 in RXTE data in 1996-2000. Three bursts were short in duration (~10 s), whereas the others lasted for ~6-25 min. Five of the long bursts showed evidence for radius expansion of the neutron star photosphere. No correlations of the burst properties with respect to the persistent X-ray spectral properties are seen, suggesting no correlation with inferred persistent mass accretion rate. The presence of short bursts in GX 17+2 and other bright X-ray sources, i.e. Cyg X-2, GX 3+1 and GX 13+1, as well as the ABSENCE of bursts in the bright X-ray sources Sco X-1, GX 5-1, GX 340+0, GX 349+2, GX 9+1 and GX 9+9 is not accounted for in the current X-ray bursts theories at the high mass accretion rates encountered in these sources. We find that in contrast to previous suggestions the persistent black-body emission does NOT arise from the same site as the burst emission. The black-body component of the persistent emission is consistent with arising in an expande...

  13. Temporal Study of Magnetar Bursts with Rossi X-ray Timing Explorer

    Science.gov (United States)

    Sasmaz Mus, Sinem; Gogus, Ersin; Kaneko, Yuki

    2016-07-01

    We performed detailed temporal analyses of all bursts observed with the Rossi X-ray Timing Explorer originated from four magnetars: SGR 1806-20, SGR 1900+14, SGR J1550-5418, and AXP 1E 2259+586. We first implemented a Bayesian block algorithm to identify bursts, and constructed Bayesian block representations of all identified bursts from these magnetars. Based on these results, we formed the burst duration distributions, and compared to those previously reported using different approach. We also performed detailed investigation of time lag between various energy intervals in order to uncover any possible time delay between soft and hard X-ray emission components.

  14. X-ray Spectroscopy of Bursts from SGR 1806-20 with RXTE

    CERN Document Server

    Strohmayer, T E; Strohmayer, Tod E.; Ibrahim, Alaa

    1998-01-01

    We report on new RXTE X-ray spectral analysis of bursts from SGR 1806-20, the most prolific SGR source known. Previous studies of bursts from this source revealed a remarkable lack of spectral variability both in single bursts as well as from burst to burst. We present here some of the first evidence for significant spectral evolution within SGR bursts. We find that optically thin thermal bremsstrahlung (OTTB) spectra including photoelectric absorption provide the best fits to most bursts, however, other models (power law, Band GRB) can also produce statistically acceptable fits. We confirm the existence of a rolloff in the photon number spectrum below 5 keV.

  15. A fundamental plane for gamma-ray bursts with X-ray plateaus

    CERN Document Server

    Dainotti, Maria Giovanna; Hernandez, Xavier; Ostrowski, Michał

    2016-01-01

    A class of long Gamma-Ray Bursts (GRBs) presenting light curves with an extended plateau phase in their X-ray afterglows obeys a correlation between the rest frame end time of the plateau, $T_a$, and its corresponding X-ray luminosity, $L_{a}$, Dainotti et al. (2008). In this work we perform an analysis of a total sample of 176 {\\it Swift} GRBs with known redshifts, exhibiting afterglow plateaus. By adding a third parameter, that is the peak luminosity in the prompt emission, $L_{peak}$, we discover the existence of a new three parameter correlation, a GRB `fundamental plane'. The scatter of data about this plane becomes smaller when a class-specific GRB sample is defined. This sample of 122 GRBs is selected from the total sample by excluding GRBs with associated Supernovae (SNe), X-ray flashes and short GRBs with extended emission. Moreover, we further limit our analysis to GRBs with lightcurves having good data coverage and almost flat plateaus, 40 GRBs forming our `gold sample'. The intrinsic scatter, $\\si...

  16. Accretion Disk Signatures in Type I X-Ray Bursts: Prospects for Future Missions

    Science.gov (United States)

    Keek, L.; Wolf, Z.; Ballantyne, D. R.

    2016-07-01

    Type I X-ray bursts and superbursts from accreting neutron stars illuminate the accretion disk and produce a reflection signal that evolves as the burst fades. Examining the evolution of reflection features in the spectra will provide insight into the burst-disk interaction, a potentially powerful probe of accretion disk physics. At present, reflection has been observed during only two bursts of exceptional duration. We investigate the detectability of reflection signatures with four of the latest well-studied X-ray observatory concepts: Hitomi, Neutron Star Interior Composition Explorer (NICER), Athena, and Large Observatory For X-ray Timing (LOFT). Burst spectra are modeled for different values for the flux, temperature, and the disk ionization parameter, which are representative for most known bursts and sources. The effective area and throughput of a Hitomi-like telescope are insufficient for characterizing burst reflection features. NICER and Athena will detect reflection signatures in Type I bursts with peak fluxes ≳10-7.5 erg cm-2 s-1 and also effectively constrain the reflection parameters for bright bursts with fluxes of ˜10-7 erg cm-2 s-1 in exposures of several seconds. Thus, these observatories will provide crucial new insight into the interaction of accretion flows and X-ray bursts. For sources with low line-of-sight absorption, the wide bandpass of these instruments allows for the detection of soft X-ray reflection features, which are sensitive to the disk metallicity and density. The large collecting area that is part of the LOFT design would revolutionize the field by tracing the evolution of the accretion geometry in detail throughout short bursts.

  17. Evidence of 1122 Hz X-ray burst oscillations from the neutron star X-ray transient XTE J1739-285

    DEFF Research Database (Denmark)

    Kaaret, P.; Prieskorn, Z.; in 't Zand, J.J.M.

    2007-01-01

    We report on millisecond variability from the X-ray transient XTE J1739-285. We detected six X-ray type I bursts and found evidence for oscillations at 1122 +/- 0.3 Hz in the brightest X-ray burst. Taking into consideration the power in the oscillations and the number of trials in the search, the...... ranging from 757 to 862 Hz. Using the brightest burst, we derive an upper limit on the source distance of about 10.6 kpc....

  18. One-dimensional Turbulence Models of Type I X-ray Bursts

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Chen [Univ. of Minnesota, Minneapolis, MN (United States)

    2016-01-06

    Type I X-ray bursts are caused by thermonuclear explosions occurring on the surface of an accreting neutron star in a binary star system. Observations and simulations of these phenomena are of great importance for understanding the fundamental properties of neutron stars and dense matter because the equation of state for cold dense matter can be constrained by the mass-radius relationship of neutron stars. During the bursts, turbulence plays a key role in mixing the fuels and driving the unstable nuclear burning process. This dissertation presents one-dimensional models of photospheric radius expansion bursts with a new approach to simulate turbulent advection. Compared with the traditional mixing length theory, the one-dimensional turbulence (ODT) model represents turbulent motions by a sequence of maps that are generated according to a stochastic process. The light curves I obtained with the ODT models are in good agreement with those of the KEPLER model in which the mixing length theory and various diffusive processes are applied. The abundance comparison, however, indicates that the differences in turbulent regions and turbulent diffusivities result in more 12C survival during the bursts in the ODT models, which can make a difference in the superbursts phenomena triggered by unstable carbon burning.

  19. ESA's X-ray space telescope proves supernovae can cause mysterious gamma-ray bursts

    Science.gov (United States)

    2002-04-01

    By analysing the afterglow of the gamma-ray burst in the X-ray light, scientists produced the first ever evidence of the presence of chemical elements which were the unmistakable remnants of a supernova explosion which had occurred just a few days before. "We can now confidently say that the death of a massive star, a supernova, was the cause of a gamma-ray burst. However we still don't know exactly how and why these bursts, the most energetic phenomena in the Universe, are triggered," says ESA astronomer Norbert Schartel, a co-author of the original paper, published today in Nature. Gamma-ray bursts were first discovered in 1967 by chance, when satellites designed to look for violations of the Nuclear Test Ban Treaty detected strong gamma-ray emissions coming from sources not in the vicinity of Earth, but from outer space. They have been a mystery ever since. They occur as often as several times a day but last for no longer than a couple of minutes, and there is no way to predict when or where the next burst will occur. Consequently they are very difficult to study. For three decades it was not even known whether the explosions were close, in our own Milky Way galaxy, or far away in distant galaxies. But astronomers set up an 'alert system'. This allows them to see the 'afterglow' of the burst before it fades away, by quickly aiming their telescopes at the precise location in the sky shortly after a detector triggers the alert. It is now clear that the bursts occur in galaxies millions of light-years away. The longest burst Technically called 'GRB 011211', it was first detected on 11 December 2001 at 19:09:21 (Universal Time), by the Italian-Dutch satellite BeppoSAX. The burst lasted for 270 seconds - the longest one observed by the satellite. A few hours afterwards, when a first analysis confirmed that a burst had indeed been registered, the BeppoSAX team alerted the rest of the astronomical community. ESA's XMM-Newton arrived on the scene 11 hours after the

  20. Future Probes of the Neutron Star Equation of State Using X-ray Bursts

    Science.gov (United States)

    Strohmayer, Tod E.

    2004-01-01

    Observations with NASA s Rossi X-ray Timing Explorer (RXTE) have resulted in the discovery of fast (200 - 600 Hz), coherent X-ray intensity oscillations (hereafter, %urstoscillations ) during thermonuclear X-ray bursts from 12 low mass X-ray binaries (LMXBs). Although many of their detailed properties remain to be fully understood, it is now beyond doubt that these oscillations result from spin modulation of the thermonuclear burst flux from the neutron star surface. Among the new timing phenomena revealed by RXTE the burst oscillations are perhaps the best understood, in the sense that many of their properties can be explained in the framework of this relatively simple model. Because of this, detailed modelling of burst oscillations can be an extremely powerful probe of neutron star structure, and thus the equation of state (EOS) of supra-nuclear density matter. Both the compactness parameter beta = GM/c(sup 2)R, and the surface velocity, nu(sub rot) = Omega(sub spin)R, are encoded in the energy-dependent amplitude and shape of the modulation pulses. The new discoveries have spurred much new theoretical work on thermonuclear burning and propagation on neutron stars, so that in the near future it is not unreasonable to think that detailed physical models of the time dependent flux from burning neutron stars will be available for comparison with the observed pulse profiles from a future, large collecting area X-ray timing observatory. In addition, recent high resolution burst spectroscopy with XMM/Newton suggests the presence of redshifted absorption lines from the neutron star surface during bursts. This leads to the possibility of using large area, high spectral resolution measurements of X-ray bursts as a precise probe of neutron star structure. In this work I will explore the precision with which constraints on neutron star structure, and hence the dense matter EOS, can be made with the implementation of such programs.

  1. X-ray burst induced spectral variability in 4U 1728-34

    CERN Document Server

    Kajava, J J E; Kuulkers, E; Poutanen, J

    2016-01-01

    Aims. INTEGRAL has been monitoring the Galactic center region for more than a decade. Over this time INTEGRAL has detected hundreds of type-I X-ray bursts from the neutron star low-mass X-ray binary 4U 1728-34, a.k.a. "the slow burster". Our aim is to study the connection between the persistent X-ray spectra and the X-ray burst spectra in a broad spectral range. Methods. We performed spectral modeling of the persistent emission and the X-ray burst emission of 4U 1728-34 using data from the INTEGRAL JEM-X and IBIS/ISGRI instruments. Results. We constructed a hardness intensity diagram to track spectral state variations. In the soft state the energy spectra are characterized by two thermal components - likely from the accretion disc and the boundary/spreading layer - together with a weak hard X-ray tail that we detect in 4U 1728-34 for the first time in the 40 to 80 keV range. In the hard state the source is detected up to 200 keV and the spectrum can be described by a thermal Comptonization model plus an addit...

  2. The WATCH solar X-ray burst catalogue

    DEFF Research Database (Denmark)

    Crosby, N.; Lund, Niels; Vilmer, N.

    1998-01-01

    The WATCH experiment aboard the GRANAT satellite provides observations of the Sun in the deka-keV range covering the years 1990 through mid-1992. An introduction to the experiment is given followed by an explanation of how the WATCH solar burst catalogue was created. The different parameters listed...

  3. Type I X-ray bursts and burst oscillations in the accreting millisecond X-ray pulsar IGR J17511-3057

    CERN Document Server

    Altamirano, D; Linares, M; Markwardt, C B; Strohmayer, T; Patruno, A

    2010-01-01

    We report the discovery of burst oscillations at the spin frequency in ten thermonuclear bursts from the accreting millisecond X-ray pulsar (AMXP) IGR J17511-3057. The burst oscillation properties are, like those from the AMXPs SAX J1808.4-3658 and XTE J1814-338, anomalous compared to burst oscillations from intermittent pulsars or non-pulsing LMXBs. Like SAX J1808.4-3658 they show frequency drifts in the rising phase rather than the tail. There is also evidence for harmonic content. Where IGR J17511-3057 is unusual compared to the other pulsars is that oscillations are not detected throughout all bursts. As accretion rate drops the bursts get brighter and their rise/decay time scales become shorter, while the oscillation amplitude falls below the detection threshold: first in the burst peak and then also in the rise. None of the bursts from IGR J17511-3057 show evidence for photospheric radius expansion (which might be expected to suppress oscillation amplitude) which allow us to set an upper limit to the di...

  4. Future Probes of the Neutron Star Equation of State Using X-ray Bursts

    CERN Document Server

    Strohmayer, T E

    2004-01-01

    Observations with NASA's Rossi X-ray Timing Explorer (RXTE) have resulted in the discovery of fast (200 - 600 Hz), coherent X-ray intensity oscillations (hereafter, "burst oscillations") during thermonuclear X-ray bursts from 12 low mass X-ray binaries (LMXBs). It is now beyond doubt that these oscillations result from spin modulation of the thermonuclear burst flux from the neutron star surface. Among the new timing phenomena revealed by RXTE the burst oscillations are perhaps the best understood, in the sense that many of their properties can be explained in the framework of this relatively simple model. Because of this, detailed modelling of burst oscillations can be an extremely powerful probe of neutron star structure, and thus the equation of state (EOS) of supra-nuclear density matter. The new discoveries have spurred much new theoretical work on thermonuclear burning and propagation on neutron stars, so that in the near future it is not unreasonable to think that detailed physical models of the time d...

  5. Nonradial g-mode oscillations in X-ray bursting neutron stars

    Science.gov (United States)

    Mcdermott, P. N.; Taam, Ronald E.

    1987-01-01

    The oscillation spectrum of nonradial g-modes in X-ray bursting neutron stars has been studied. The pulsation periods are found to be sensitive to the envelope temperature and range from about 15 ms to about 50 ms for the l = 1 g(1) mode during the X-ray burst. From a quasi-adiabatic stability analysis it is likely that a spectrum of l-pole g-modes is unstable due to the epsilon-mechanism associated with rapid alpha captures. As the thermal structure of the envelope of the neutron star changes on time scales less than 0.2 s during the rise of the X-ray burst, the oscillations are expected to be quasi-coherent during this phase. The calculated period derivatives are large during the burst and are about 1 ms/s. The pulsations are short-lived and are most likely to be seen in the immediate vicinity of the burst peak. Finally, the possible relevance of nonradial g-mode pulsations to the recently discovered quasi-periodic oscillations observed in a number of X-ray sources is discussed.

  6. A study of hard X-ray associated meter-decameter bursts observed on December 19, 1979

    Science.gov (United States)

    Kundu, M. R.; Gergely, T. E.; Kane, S. R.; Sawant, H. S.

    1986-01-01

    The results of a study of the relationship of a complex meter-decameter wavelength radio burst observed with the Clark Lake E-W and N-S interferometers, with a hard X-ray burst observed with the X-ray spectrometer aboard ISEE-3 are presented. The radio burst consisted of several type III's, reverse drift type III's, a U burst, and type II and type IV bursts. The X-ray emission was also complex. The radio as well as hard X-ray emissions were observed before the flash phase of the flare; they were not always associated and it is conjectured that this may constitute evidence for acceleration of electrons high in the corona. On the other hand, all components of the reverse drift burst were associated with hard X-ray subpeaks, indicating multiple injection of electron beams along field lines with different density gradients. While the type II burst appeared to be related to the hard X-ray burst, a detailed correspondence between individual features of the radio and hard X-ray burst emissions could not be found. The type IV burst started after all hard X-ray emissions ceased. Its source appeared to be a magnetic arch, presumably containing energetic electrons reponsible for the gyrosynchrotron radiation of type IV.

  7. Self-organized criticality in X-ray flares of gamma-ray burst afterglows

    CERN Document Server

    Wang, F Y

    2013-01-01

    X-ray flares detected in nearly half of gamma-ray burst (GRB) afterglows are one of the most intriguing phenomena in high-energy astrophysics. All the observations indicate that the central engines of bursts, after the gamma-ray emission has ended, still have long periods of activity, during which energetic explosions eject relativistic materials, leading to late-time X-ray emission. It is thus expected that X-ray flares provide important clues to the nature of the central engines of GRBs, and more importantly, unveil the physical mechanism of the flares themselves, which has so far remained mysterious. Here we report statistical results of X-ray flares of GRBs with known redshifts, and show that X-ray flares and solar flares share three statistical properties: power-law frequency distributions for energies, durations, and waiting times. All of the distributions can be well understood within the physical framework of a self-organized criticality (SOC) system. The statistical properties of X-ray flares of GRBs...

  8. ANISOTROPY OF X-RAY BURSTS FROM NEUTRON STARS WITH CONCAVE ACCRETION DISKS

    Energy Technology Data Exchange (ETDEWEB)

    He, C.-C. [College of Physics, Jilin University, Changchun 130012 (China); Keek, L., E-mail: jordanhe1994@gmail.com [CRESST and X-ray Astrophysics Laboratory NASA/GSFC, Greenbelt, MD 20771 (United States)

    2016-03-01

    Emission from neutron stars and accretion disks in low-mass X-ray binaries is anisotropic. The non-spherical shape of the disk as well as blocking of the neutron star by the disk make the observed flux dependent on the inclination angle of the disk with respect to the line of sight. This is of importance for the interpretation of thermonuclear X-ray bursts from neutron stars. Because part of the X-ray burst is reflected off the disk, the observed burst flux depends on the anisotropies for both direct emission from the neutron star and reflection off the disk. This influences measurements of source distance, mass accretion rate, and constraints on the neutron star’s equation of state. Previous predictions of the anisotropy factors assumed a geometrically flat disk. Detailed observations of two so-called superbursts allowed for the direct and the reflected burst fluxes to each be measured separately. The reflection fraction was much higher than what the anisotropies of a flat disk can account for. We create numerical models to calculate the anisotropy factors for different disk shapes, including concave disks. We present the anisotropy factors of the direct and reflected burst fluxes separately, as well as the anisotropy of the persistent flux. Reflection fractions substantially larger than unity are produced in the case where the inner accretion disk increases steeply in height, such that part of the star is blocked from view. Such a geometry could possibly be induced by the X-ray burst if X-ray heating causes the inner disk to puff up.

  9. Discovery of type-I X-ray bursts from the low-mass X-ray binary 4U 1708-40

    CERN Document Server

    Migliari, S; Belloni, T; Van der Klis, M; Fender, R P; Campana, S; Kouveliotou, C; Méndez, M; Lewin, W H G

    2003-01-01

    We report the discovery of type-I X-ray bursts from the low-mass X-ray binary 4U 1708-40 during the 100 ks observation performed by BeppoSAX on 1999 August 15-16. Six X-ray bursts have been observed. The unabsorbed 2-10 keV fluxes of the bursts range from ~ (3-9)x10^(-10) erg cm^(-2)s^(-1). A correlation between peak flux and fluence of the bursts is found, in agreement with the behaviour observed in other similar sources. There is a trend of the burst flux to increase with the time interval from the previous burst. From the value of the persistent flux we infer a mass accretion rate Mdot~7x10^(-11) Msun/yr, that may correspond to the mixed hydrogen/helium burning regime triggered by thermally unstable hydrogen. We have also analysed a BeppoSAX observation performed on 2001 August 22 and previous RXTE observations of 4U 1708-40, where no bursts have been observed; we found persistent fluxes of more than a factor of 7 higher than the persistent flux observed during the BeppoSAX observation showing X-ray bursts...

  10. X-ray Optics for BES Light Source Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Mills, Dennis [Argonne National Lab. (ANL), Argonne, IL (United States); Padmore, Howard [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Lessner, Eliane [Dept. of Energy (DOE), Washington DC (United States). Office of Science

    2013-03-27

    potentially revolutionary science involves soft excitations such as magnons and phonons; in general, these are well below the resolution that can be probed by today’s optical systems. The study of these low-energy excitations will only move forward if advances are made in high-resolution gratings for the soft X-ray energy region, and higher-resolution crystal analyzers for the hard X-ray region. In almost all the forefront areas of X-ray science today, the main limitation is our ability to focus, monochromate, and manipulate X-rays at the level required for these advanced measurements. To address these issues, the U.S. Department of Energy (DOE) Office of Basic Energy Sciences (BES) sponsored a workshop, X-ray Optics for BES Light Source Facilities, which was held March 27–29, 2013, near Washington, D.C. The workshop addressed a wide range of technical and organizational issues. Eleven working groups were formed in advance of the meeting and sought over several months to define the most pressing problems and emerging opportunities and to propose the best routes forward for a focused R&D program to solve these problems. The workshop participants identified eight principal research directions (PRDs), as follows: Development of advanced grating lithography and manufacturing for high-energy resolution techniques such as soft X-ray inelastic scattering. Development of higher-precision mirrors for brightness preservation through the use of advanced metrology in manufacturing, improvements in manufacturing techniques, and in mechanical mounting and cooling. Development of higher-accuracy optical metrology that can be used in manufacturing, verification, and testing of optomechanical systems, as well as at wavelength metrology that can be used for quantification of individual optics and alignment and testing of beamlines. Development of an integrated optical modeling and design framework that is designed and maintained specifically for X-ray optics. Development of

  11. X-ray Optics for BES Light Source Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Mills, Dennis [Argonne National Lab. (ANL), Argonne, IL (United States); Padmore, Howard [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Lessner, Eliane [Dept. of Energy (DOE), Washington DC (United States). Office of Science

    2013-03-27

    potentially revolutionary science involves soft excitations such as magnons and phonons; in general, these are well below the resolution that can be probed by today’s optical systems. The study of these low-energy excitations will only move forward if advances are made in high-resolution gratings for the soft X-ray energy region, and higher-resolution crystal analyzers for the hard X-ray region. In almost all the forefront areas of X-ray science today, the main limitation is our ability to focus, monochromate, and manipulate X-rays at the level required for these advanced measurements. To address these issues, the U.S. Department of Energy (DOE) Office of Basic Energy Sciences (BES) sponsored a workshop, X-ray Optics for BES Light Source Facilities, which was held March 27–29, 2013, near Washington, D.C. The workshop addressed a wide range of technical and organizational issues. Eleven working groups were formed in advance of the meeting and sought over several months to define the most pressing problems and emerging opportunities and to propose the best routes forward for a focused R&D program to solve these problems. The workshop participants identified eight principal research directions (PRDs), as follows: Development of advanced grating lithography and manufacturing for high-energy resolution techniques such as soft X-ray inelastic scattering. Development of higher-precision mirrors for brightness preservation through the use of advanced metrology in manufacturing, improvements in manufacturing techniques, and in mechanical mounting and cooling. Development of higher-accuracy optical metrology that can be used in manufacturing, verification, and testing of optomechanical systems, as well as at wavelength metrology that can be used for quantification of individual optics and alignment and testing of beamlines. Development of an integrated optical modeling and design framework that is designed and maintained specifically for X-ray optics. Development of

  12. Windowless microfluidic platform based on capillary burst valves for high intensity x-ray measurements

    DEFF Research Database (Denmark)

    Vig, Asger Laurberg; Haldrup, Kristoffer; Enevoldsen, Nikolaj Brandt;

    2009-01-01

    We propose and describe a microfluidic system for high intensity x-ray measurements. The required open access to a microfluidic channel is provided by an out-of-plane capillary burst valve (CBV). The functionality of the out-of-plane CBV is characterized with respect to the diameter of the window...

  13. Compact X-ray Light Source Workshop Report

    Energy Technology Data Exchange (ETDEWEB)

    Thevuthasan, Suntharampillai; Evans, James E.; Terminello, Louis J.; Koppenaal, David W.; Manke, Kristin L.; Plata, Charity

    2012-12-01

    This report, produced jointly by EMSL and FCSD, is the result of a workshop held in September 2011 that examined the utility of a compact x-ray light source (CXLS) in addressing many scientific challenges critical to advancing energy science and technology.

  14. Accretion disk signatures in Type I X-ray Bursts: prospects for future missions

    CERN Document Server

    Keek, L; Ballantyne, D R

    2016-01-01

    Type I X-ray bursts and superbursts from accreting neutron stars illuminate the accretion disk and produce a reflection signal that evolves as the burst fades. Examining the evolution of reflection features in the spectra will give insight into the burst-disk interaction, a potentially powerful probe of accretion disk physics. At present, reflection has been observed during only two bursts of exceptional duration. We investigate the detectability of reflection signatures with four of the latest well-studied X-ray observatory concepts: Hitomi, NICER, Athena, and LOFT. Burst spectra are modeled for different values for the flux, temperature, and the disk ionization parameter, which are representative for most known bursts and sources. The effective area and through-put of a Hitomi-like telescope are insufficient for characterizing burst reflection features. NICER and Athena will detect reflection signatures in Type I bursts with peak fluxes $\\ge 10^{-7.5}$ erg cm$^{-2}$ s$^{-1}$, and also effectively constrain ...

  15. Hard X-rays from Type II bursts of the Rapid Burster and its transition toward quiescence

    CERN Document Server

    Masetti, N; Stella, L; Orlandini, M; Parmar, A N; Del Sordo, S; Amati, L; Palazzi, E; Dal Fiume, D; Cusumano, G; Pareschi, G; Lapidus, I; Remillard, R A

    2000-01-01

    We report on 4 BeppoSAX Target Of Opportunity observations of MXB 1730-335, the Rapid Burster (RB), made during the 1998 February-March outburst. In the first observation, approximately 20 days after the outburst peak, the X-ray light curve showed Type II bursts at a rate of 43 per hour. Nine days later, during the second BeppoSAX pointing, only 5 Type II bursts were detected at the beginning of the observation. During the third pointing no X-ray bursts were detected and in the fourth and final observation the RB was not detected at all. Persistent emission from the RB was detected up to 10 keV during the first three pointings. The spectra of the persistent and bursting emissions below 10 keV were best fit with a model consisting of two blackbodies. An additional component (a power law) was needed to describe the 1-100 keV bursting spectrum when the persistent emission was subtracted. To our knowledge, this is the first detection of the RB beyond 20 keV. We discuss the evolution of the spectral parameters for...

  16. High-Resolution X-Ray Spectroscopy of the Bursting Pulsar GRO J1744-28

    CERN Document Server

    Degenaar, N; Harrison, F A; Kennea, J A; Kouveliotou, C; Younes, G

    2014-01-01

    The bursting pulsar GRO J1744-28 is a Galactic low-mass X-ray binary that distinguishes itself by displaying type-II X-ray bursts: brief, bright flashes of X-ray emission that likely arise from spasmodic accretion. Combined with its coherent 2.1 Hz X-ray pulsations and relatively high estimated magnetic field, it is a particularly interesting source to study the physics of accretion flows around neutron stars. Here we report on Chandra/HETG observations obtained near the peak of its bright 2014 accretion outburst. Spectral analysis suggests the presence of a broad iron emission line centered at E_l ~ 6.7 keV. Fits with a disk reflection model yield an inclination angle of i ~ 52 degrees and an inner disk radius of R_in ~ 85 GM/c^2, which is much further out than typically found for neutron star low-mass X-ray binaries. Assuming that the disk is truncated at the magnetospheric radius of the neutron star, we estimate a magnetic field strength of B ~ (2-6)E10 G. Furthermore, we identify an absorption feature nea...

  17. POLAR - novel hard X-ray polarimeter for Gamma Ray Bursts

    Science.gov (United States)

    Hajdas, Wojtek

    Our present knowledge of the Gamma Ray Bursts GRBs - the most powerful explosions in the universe after the Big Bang - links them with a birth of the black holes and localize at cosmological distances. There is also a strong evidence relating some of them with Supernovae and thus with gravitational waves. Despite of such significant role of GRBs only little is known about their mechanisms and progenitors. Existing theories still have troubles describing bursts prompt emissions while predictions of the photon polarization show large divergences. On the observational side there are just few isolated measurements of the hard X-ray polarization affected by large experimental uncertainties. Nevertheless, it became clear that determining the GRB polarization could be an ultimate step for understanding their genuine nature. To participate in this task we propose POLAR - novel instrument for hard X-ray and low energy gamma ray polarimetry. The instrument goal is to perform highly precise polarization studies from a very large number of GRBs. Measurements of the linear polarization in the GRB prompt emission at photon energies from 5 keV to 500 keV will be carried out using continuous observations of the sky. Our calculations showed that for several bursts per year the experimental precision will reach a 1 sigma level of 3 per cent. For the strongest events it will be possible to study polarization as a function of energy achieving much more detailed view of the emitting system structure. POLAR uses a uniform array of 1600 weakly shielded plastic detectors coupled with the new multi-anode photo-multipliers. The polarization measurement is based on Compton scattering and relies on detection of fast coincidences between plastic scintillator bars. The total mass (28 kg) and power requirements (30 W) are very moderate. POLAR has relatively small dimensions and it was designed to be not only non-intrusive but also highly adaptable. The qualification model is currently under

  18. Simultaneous optical and X-ray bursts from 4U/MXB 1636-53

    Science.gov (United States)

    Pedersen, H.; Lub, J.; Inoue, H.; Koyama, K.; Makishima, K.; Matsuoka, M.; Mitsuda, K.; Murakami, T.; Oda, M.; Ogawara, Y.

    1982-01-01

    Methods of obtaining information about the geometry of X-ray burster systems from simultaneous optical and X-ray observations are discussed, and such simultaneous observations of 4U/MXB 1636-53 are reported. The physical idea of an optical burst being due to reprocessing of an X-ray burst in material in the vicinity of the compact object is discussed. The resulting modification of the X-ray burst signal is described in terms of an optical response function. Delay and smearing due to radiative processes are discussed along with those due to the geometry. For 4U/MXB 1636-53, the estimated delay is 2.5 seconds, the smearing is less than four seconds, and the maximum temperature of the reprocessing region is about 75,000 K. The projected area of the reprocessing region is about 6 x 10 to the 21st square cm. The neutron star is about 1.4 solar masses, the radius of the accretion disk is greater than 1.5 lt-sec, and the mass of the Roche lobe filling companion star is less than 2.0 solar masses, corresponding to a binary period between about one and ten hours.

  19. Hard X-Ray Burst Detected From Caltech Plasma Jet Experiment Magnetic Reconnection Event

    Science.gov (United States)

    Marshall, Ryan S.; Bellan, Paul M.

    2016-10-01

    In the Caltech plasma jet experiment a 100 kA MHD driven jet becomes kink unstable leading to a Rayleigh-Taylor instability that quickly causes a magnetic reconnection event. Movies show that the Rayleigh-Taylor instability is simultaneous with voltage spikes across the electrodes that provide the current that drives the jet. Hard x-rays between 4 keV and 9 keV have now been observed using an x-ray scintillator detector mounted just outside of a kapton window on the vacuum chamber. Preliminary results indicate that the timing of the x-ray burst coincides with a voltage spike on the electrodes occurring in association with the Rayleigh-Taylor event. The x-ray signal accompanies the voltage spike and Rayleigh-Taylor event in approximately 50% of the shots. A possible explanation for why the x-ray signal is sometimes missing is that the magnetic reconnection event may be localized to a specific region of the plasma outside the line of sight of the scintillator. The x-ray signal has also been seen accompanying the voltage spike when no Rayleigh-Taylor is observed. This may be due to the interframe timing on the camera being longer than the very short duration of the Rayleigh-Taylor instability.

  20. Millihertz Oscillation Frequency Drift Predicts the Occurrence of Type I X-ray Bursts

    CERN Document Server

    Altamirano, D; Wijnandsm, R; Cumming, A

    2007-01-01

    Millihertz quasi-periodic oscillations reported in three neutron-star low mass X-ray binaries have been suggested to be a mode of marginally stable nuclear burning on the neutron star surface. In this Letter, we show that close to the transition between the island and the banana state, 4U~1636--53 shows mHz QPOs whose frequency systematically decreases with time until the oscillations disappear and a Type I X-ray burst occurs. There is a strong correlation between the QPO frequency $\

  1. The Swift capture of a long X-ray burst from XTE J1701-407

    CERN Document Server

    Linares, Manuel; Wijnands, Rudy; Soleri, Paolo; Degenaar, Nathalie; Curran, Peter A; Starling, Rhaana L C; van der Klis, Michiel

    2008-01-01

    XTE J1701-407 is a new transient X-ray source discovered on June 8th, 2008. More than one month later it showed a rare type of thermonuclear explosion: a long type I X-ray burst. We report herein the results of our study of the spectral and flux evolution during this burst, as well as the analysis of the outburst in which it took place. We find an upper limit on the distance to the source of 6.2 kpc by considering the maximum luminosity reached by the burst. We measure a total fluence of 3.5*10^{-6} erg/cm^2 throughout the ~20 minutes burst duration and a fluence of 2.6*10^{-3} erg/cm^2 during the first two months of the outburst. We show that the flux decay is best fitted by a power law (index ~1.6) along the tail of the burst. Finally, we discuss the implications of the long burst properties, and the presence of a second and shorter burst detected by Swift ten days later, for the composition of the accreted material and the heating of the burning layer.

  2. A search for thermal X-ray signatures in Gamma-Ray Bursts I: Swift bursts with optical supernovae

    CERN Document Server

    Starling, R L C; Pe'er, A; Beardmore, A P; Osborne, J P

    2012-01-01

    The X-ray spectra of Gamma-Ray Bursts can generally be described by an absorbed power law. The landmark discovery of thermal X-ray emission in addition to the power law in the unusual GRB 060218, followed by a similar discovery in GRB 100316D, showed that during the first thousand seconds after trigger the soft X-ray spectra can be complex. Both the origin and prevalence of such spectral components still evades understanding, particularly after the discovery of thermal X-ray emission in the classical GRB 090618. Possibly most importantly, these three objects are all associated with optical supernovae, begging the question of whether the thermal X-ray components could be a result of the GRB-SN connection, possibly in the shock breakout. We therefore performed a search for blackbody components in the early Swift X-ray spectra of 11 GRBs that have or may have associated optical supernovae, accurately recovering the thermal components reported in the literature for GRBs 060218, 090618 and 100316D. We present the ...

  3. Evidence that the Bursting Component of the X-ray Radiation From 3C 111 Originates in the PC-Scale Jet

    CERN Document Server

    Bell, M B

    2011-01-01

    Evidence is presented indicating that the bursting component of the X-ray radiation detected in the nuclear region of the active radio galaxy 3C 111 comes from the blobs ejected in the pc-scale jet and not from the accretion disc. After each new outburst the radio flux density associated with it increases to a peak in ~1 year and then subsides over a period of 1-2 years with the flux falling off exponentially as the blob moves outward and dissipates. Similar peaks (bursts) are seen in the X-ray light curve and a cross-correlation between the two shows a very high correlation with the X-ray peaks leading the radio peaks by ~100 days. A second cross-correlation, this time between the radio event start times and the X-ray light curve, also shows a significant correlation. When this is taken together with the long (~1 yr) delay between the start of each ejection event and its associated X-ray peak it indicates that this bursting component of the X-ray flux must be associated with the ejected blobs in the pc-scale...

  4. A CHANDRA OBSERVATION OF THE BURSTING MILLISECOND X-RAY PULSAR IGR J17511-3057

    Energy Technology Data Exchange (ETDEWEB)

    Paizis, A. [Istituto Nazionale di Astrofisica, INAF-IASF, Via Bassini 15, 20133 Milano (Italy); Nowak, M. A. [Massachusetts Institute of Technology, Kavli Institute for Astrophysics, Cambridge, MA 02139 (United States); Rodriguez, J.; Chaty, S. [Astrophysique, Instrumentation et Modelisation (AIM, UMR-E 9005 CEA/DSM-CNRS-Universite Paris Diderot) Irfu/Service d' Astrophysique, Centre de Saclay, F-91191 Gif-sur-Yvette Cedex (France); Wilms, J. [Dr. Karl Remeis-Sternwarte and Erlangen Centre for Astroparticle Physics, Universitaet Erlangen-Nuernberg, Sternwartstr. 7, 96049 Bamberg (Germany); Del Santo, M.; Ubertini, P., E-mail: ada@iasf-milano.inaf.it, E-mail: mnowak@space.mit.edu [IAPS, INAF, Via Fosso del Cavaliere 100, 00133 Rome (Italy)

    2012-08-10

    IGR J17511-3057 is a low-mass X-ray binary hosting a neutron star and is one of the few accreting millisecond X-ray pulsars with X-ray bursts. We report on a 20 ks Chandra grating observation of IGR J17511-3057, performed on 2009 September 22. We determine the most accurate X-ray position of IGR J17511-3057, {alpha}{sub J2000} = 17{sup h}51{sup m}08.{sup s}66, {delta}{sub J2000} = -30 Degree-Sign 57'41.''0 (90% uncertainty of 0.''6). During the observation, a {approx}54 s long type-I X-ray burst is detected. The persistent (non-burst) emission has an absorbed 0.5-8 keV luminosity of 1.7 Multiplication-Sign 10{sup 36} erg s{sup -1} (at 6.9 kpc) and can be well described by a thermal Comptonization model of soft, {approx}0.6 keV, seed photons upscattered by a hot corona. The type-I X-ray burst spectrum, with average luminosity over the 54 s duration L{sub 0.5-8{sub keV}} = 1.6 Multiplication-Sign 10{sup 37} erg s{sup -1}, can be well described by a blackbody with kT{sub bb} {approx} 1.6 keV and R{sub bb} {approx} 5 km. While an evolution in temperature of the blackbody can be appreciated throughout the burst (average peak kT{sub bb} = 2.5{sup +0.8}{sub -0.4} keV to tail kT{sub bb} = 1.3{sup +0.2}{sub -0.1} keV), the relative emitting surface shows no evolution. The overall persistent and type-I burst properties observed during the Chandra observation are consistent with what was previously reported during the 2009 outburst of IGR J17511-3057.

  5. Long Type I X-ray Bursts and Neutron Star Interior Physics

    CERN Document Server

    Cumming, A; in 't Zand, J J M; Page, D; Cumming, Andrew; Macbeth, Jared; Page, Dany

    2005-01-01

    Superbursts are very energetic Type I X-ray bursts discovered in recent years by long term monitoring of X-ray bursters, believed to be due to unstable ignition of carbon in the deep ocean of the neutron star. A number of "intermediate duration" bursts have also been observed, probably associated with ignition of a thick helium layer. We investigate the sensitivity of these long X-ray bursts to the thermal profile of the neutron star crust and core. We first compare cooling models of superburst lightcurves with observations, and derive constraints on the ignition mass and energy release, and then calculate ignition models for superbursts and pure helium bursts, and compare to observations. The superburst lightcurves and ignition models imply that the carbon mass fraction is approximately 20% or greater in the fuel layer, constraining models of carbon production. However, the most important result is that when Cooper pairing neutrino emission is included in the crust, the temperature is too low to support unst...

  6. The Energy Dependence of Neutron Star Surface Modes and X-ray Burst Oscillations

    CERN Document Server

    Piro, A L; Piro, Anthony L.; Bildsten, Lars

    2006-01-01

    We calculate the photon energy dependence of the pulsed amplitude of neutron star (NS) surface modes. Simple approximations demonstrate that it depends most strongly on the bursting NS surface temperature. This result compares well with full integrations that include Doppler shifts from rotation and general relativistic corrections to photon propagation. We show that the energy dependence of type I X-ray burst oscillations agrees with that of a surface mode, lending further support to the hypothesis that they originate from surface waves. The energy dependence of the pulsed emission is rather insensitive to the NS inclination, mass and radius, or type of mode, thus hindering constraints on these parameters. We also show that, for this energy-amplitude relation, the majority of the signal (relative to the noise) comes in the 2-25 keV band, so that the current burst oscillation searches with the Rossi X-Ray Timing Explorer are close to optimal. The critical test of the mode hypothesis for X-ray burst oscillatio...

  7. Numbers of Electrons in Solar Flares as Deduced from Microwave and X-Ray Bursts

    Institute of Scientific and Technical Information of China (English)

    YU Xing-Feng; YAO Jin-Xing

    2001-01-01

    We discuss whether the numbers of x-ray and radio-produced electrons in solar flares are the same. The number of radio-produced electrons that is estimated with an inhomogeneous source increases by a factor of 103 - 104because of the inhomogeneity and the decreased magnetic field (B = 120 G) of the radio source. The number of x-ray-produced electrons decreases by a factor of 10 - 30 due to the increase of the number density of ions (3 × 1010 cm-3). These are the reasons why the number of radio-produced electrons is approximately equal tothat of x-ray-produced electrons in the 1981 April 27 burst.

  8. Mass and Radius of Neutron Stars Constrained by Photospheric Radius Expansion X-ray Bursts

    Science.gov (United States)

    Kwak, Kyujin; Kim, Myungkuk; Kim, Young-Min; Lee, Chang-Hwan

    Simultaneous measurement of mass and radius of a neutron star is important because it provides strong constraint on the equation of state for nuclear matter inside a neutron star. Type I X-ray Bursts (XRBs) that have been observed in low-mass X-ray binaries sometimes show photospheric radius expansion (PRE). By combining observed fluxes, X-ray spectra, and distances of PRE XRBs and using a statistical analysis, it is possible to simultaneously constrain the mass and radius of a neutron star. However, the mass and radius of a neutron star estimated in this method depends on the opacity of accreted material. We investigate the effect of the opacity on the mass and radius estimation by taking into account the cases that the hydrogen mass fraction of accreted material has narrowly-distributed values. We present preliminary results that are investigated with three different values of hydrogen mass fraction and compare our results with previous studies.

  9. Evidence of heavy-element ashes in thermonuclear X-ray bursts with photospheric superexpansion

    CERN Document Server

    Zand, J J M in 't

    2010-01-01

    A small subset of thermonuclear X-ray bursts on neutron stars exhibit such a strong photospheric expansion that for a few seconds the photosphere is located at a radius r_ph greater than ~1000 km. Such `superexpansions' imply a large and rapid energy release, a feature characteristic of pure He burst models. Calculations have shown that during a pure He burst, the freshly synthesized heavy-element ashes of burning can be ejected in a strong radiative wind and produce significant spectral absorption features. We find 32 superexpansion bursts from 8 different systems with the following interesting features: (1) At least 7 out of 8 systems are (candidate) ultracompact X-ray binaries in which the neutron star accretes hydrogen-deficient fuel, suggesting that these bursts indeed ignite in a helium-rich layer. (2) In two bursts we detect strong absorption edges during the expansion phase. The edge energies and depths are consistent with the H-like edge of iron-peak elements with abundances greater than ~100 times s...

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

    CERN Document Server

    Ballantyne, D R

    2004-01-01

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

  11. Two-phase X-ray burst from GX 3+1 observed by INTEGRAL

    DEFF Research Database (Denmark)

    Chenevez, Jérôme; Falanga, M.F.; Brandt, Søren

    2006-01-01

    INTEGRAL detected on August 31, 2004, an unusual thermonuclear X-ray burst from the low-mass X-ray binary GX 3 3+1. Its duration was 30 min, which is between the normal burst durations for this source (less than or similar to 10 s) and the superburst observed in 1998 ( several hours). We see...... in the present case); and 3) limited carbon burning at an unusually shallow depth triggered by unstable helium ignition. Though none of these provide a satisfactory description of this uncommon event, the former one seems the most probable......., followed by a remarkable extended decay of cooling emission. We discuss three alternative schemes to explain its twofold nature: 1) unstable burning of a hydrogen hydrogen/helium layer involving an unusually large amount of hydrogen; 2) pure helium ignition at an unusually large depth ( unlikely...

  12. Comprehensive study of the X-ray flares from gamma-ray bursts observed by Swift

    CERN Document Server

    Yi, Shuang-Xi; Yu, Hai; Wang, F Y; Mu, Hui-Jun; Lv, Lian-Zhong; Liang, En-Wei

    2016-01-01

    X-ray flares are generally supposed to be produced by the later central engine activities, and may share the similar physical origin with prompt emission of gamma-ray bursts (GRBs). In this paper, we have analyzed all significant X-ray flares from the GRBs observed by {\\em Swift} from April 2005 to March 2015. The catalog contains 468 bright X-ray flares, including 200 flares with redshifts. We obtain the fitting results of X-ray flares, such as start time, peak time, duration, peak flux, fluence, peak luminosity, and mean luminosity. The peak luminosity decreases with peak time, following a power-law behavior $L_p \\propto T_{peak,z}^{-1.27}$. The flare duration increases with peak time. The 0.3-10 keV isotropic energy of X-ray flares distribution is a lognormal peaked at $10^{51.2}$ erg. We also study the frequency distributions of flare parameters, including energies, durations, peak fluxes, rise times, decay times and waiting times. Power-law distributions of energies, durations, peak fluxes, and waiting t...

  13. Multiple Plasmoid Ejections and Associated Hard X-ray Bursts in the 2000 November 24 Flare

    CERN Document Server

    Nishizuka, N; Asai, A; Shibata, K; 10.1088/0004-637X/711/2/1062

    2013-01-01

    The Soft X-ray Telescope (SXT) on board Yohkoh revealed that the ejection of X-ray emitting plasmoid is sometimes observed in a solar flare. It was found that the ejected plasmoid is strongly accelerated during a peak in the hard X-ray emission of the flare. In this paper we present an examination of the GOES X 2.3 class flare that occurred at 14.51 UT on 2000 November 24. In the SXT images we found multiple plasmoid ejections with velocities in the range of 250-1500 km/s, which showed blob-like or loop-like structures. Furthermore, we also found that each plasmoid ejection is associated with an impulsive burst of hard X-ray emission. Although some correlation between plasmoid ejection and hard X-ray emission has been discussed previously, our observation shows similar behavior for multiple plasmoid ejection such that each plasmoid ejection occurs during the strong energy release of the solar flare. As a result of temperature-emission measure analysis of such plasmoids, it was revealed that the apparent veloc...

  14. HIGH-RESOLUTION X-RAY SPECTROSCOPY OF THE BURSTING PULSAR GRO J1744-28

    Energy Technology Data Exchange (ETDEWEB)

    Degenaar, N.; Miller, J. M. [Department of Astronomy, University of Michigan, 1085 South University Avenue, Ann Arbor, MI 48109 (United States); Harrison, F. A. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Kennea, J. A. [Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802 (United States); Kouveliotou, C. [Space Science Office, ZP12, NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States); Younes, G., E-mail: degenaar@umich.edu [Universities Space Research Association, 6767 Old Madison Pike, Suite 450, Huntsville, AL 35806 (United States)

    2014-11-20

    The bursting pulsar GRO J1744-28 is a Galactic low-mass X-ray binary that distinguishes itself by displaying type-II X-ray bursts: brief, bright flashes of X-ray emission that likely arise from spasmodic accretion. Combined with its coherent 2.1 Hz X-ray pulsations and relatively high estimated magnetic field, it is a particularly interesting source to study the physics of accretion flows around neutron stars. Here we report on Chandra/High Energy Transmission Grating observations obtained near the peak of its bright 2014 accretion outburst. Spectral analysis suggests the presence of a broad iron emission line centered at E {sub l} ≅ 6.7 keV. Fits with a disk reflection model yield an inclination angle of i ≅ 52° and an inner disk radius of R {sub in} ≅ 85 GM/c {sup 2}, which is much further out than typically found for neutron star low-mass X-ray binaries. Assuming that the disk is truncated at the magnetospheric radius of the neutron star, we estimate a magnetic field strength of B ≅ (2-6) × 10{sup 10} G. Furthermore, we identify an absorption feature near ≅ 6.85 keV that could correspond to blue-shifted Fe XXV and point to a fast disk wind with an outflow velocity of v {sub out} ≅ (7.5-8.2) × 10{sup 3} km s{sup –1} (≅ 0.025c-0.027c). If the covering fraction and filling factor are large, this wind could be energetically important and perhaps account for the fact that the companion star lost significant mass while the magnetic field of the neutron star remained strong.

  15. Probing the effects of a thermonuclear X-ray burst on the neutron star accretion flow with NuSTAR

    CERN Document Server

    Degenaar, N; Chakrabarty, D; Kara, E; Altamirano, D; Miller, J M; Fabian, A C

    2016-01-01

    Observational evidence has been accumulating that thermonuclear X-ray bursts ignited on the surface of neutron stars influence the surrounding accretion flow. Here, we exploit the excellent sensitivity of NuSTAR up to 79 keV to analyze the impact of an X-ray burst on the accretion emission of the neutron star LMXB 4U 1608-52. The ~200 s long X-ray burst occurred during a hard X-ray spectral state, and had a peak intensity of ~30-50 per cent of the Eddington limit with no signs of photospheric radius expansion. Spectral analysis suggests that the accretion emission was enhanced up to a factor of ~5 during the X-ray burst. We also applied a linear unsupervised decomposition method, namely non-negative matrix factorization (NMF), to study this X-ray burst. We find that the NMF performs well in characterizing the evolution of the burst emission and is a promising technique to study changes in the underlying accretion emission in more detail than is possible through conventional spectral fitting. For the burst of ...

  16. Infrared observations of the possible X-ray counterpart to the 1992 May 1 gamma-ray burst

    NARCIS (Netherlands)

    Blaes, O; Hurt, T; Antonucci, R; Hurley, K; Smette, A

    1997-01-01

    We present the results of deep infrared imaging in J, H, and K of the quiescent X-ray source located within the 1992 May 1 gamma-ray burst error box. The field is crowded, containing both stars and galaxies, and we discuss the Likelihood that they are associated with the X-ray source. Two objects (o

  17. Dependence of X-Ray Burst Models on Nuclear Reaction Rates

    CERN Document Server

    Cyburt, R H; Heger, A; Johnson, E; Keek, L; Meisel, Z; Schatz, H; Smith, K

    2016-01-01

    X-ray bursts are thermonuclear flashes on the surface of accreting neutron stars and reliable burst models are needed to interpret observations in terms of properties of the neutron star and the binary system. We investigate the dependence of X-ray burst models on uncertainties in (p,$\\gamma$), ($\\alpha$,$\\gamma$), and ($\\alpha$,p) nuclear reaction rates using fully self-consistent burst models that account for the feedbacks between changes in nuclear energy generation and changes in astrophysical conditions. A two-step approach first identified sensitive nuclear reaction rates in a single-zone model with ignition conditions chosen to match calculations with a state-of-the-art 1D multi-zone model based on the {\\Kepler} stellar evolution code. All relevant reaction rates on neutron deficient isotopes up to mass 106 were individually varied by a factor of 100 up and down. Calculations of the 84 highest impact reaction rate changes were then repeated in the 1D multi-zone model. We find a number of uncertain reac...

  18. Time Resolved X-Ray Spectral Analysis of Class II YSOs in NGC 2264 During Optical Dips and Bursts

    Science.gov (United States)

    Guarcello, Mario Giuseppe; Flaccomio, Ettore; Micela, Giuseppina; Argiroffi, Costanza; Venuti, Laura

    2016-07-01

    Pre-Main Sequence stars are variable sources. The main mechanisms responsible for their variability are variable extinction, unsteady accretion, and rotational modulation of both hot and dark photospheric spots and X-ray active regions. In stars with disks this variability is thus related to the morphology of the inner circumstellar region (motivations of the Coordinated Synoptic Investigation of NGC2264, a set of simultaneous observations of NGC2264 with 15 different telescopes.We analyze the X-ray spectral properties of stars with disks extracted during optical bursts and dips in order to unveil the nature of these phenomena. Stars are analyzed in two different samples. In stars with variable extinction a simultaneous increase of optical extinction and X-ray absorption is searched during the optical dips; in stars with accretion bursts we search for soft X-ray emission and increasing X-ray absorption during the bursts. In 9/33 stars with variable extinction we observe simultaneous increase of X-ray absorption and optical extinction. In seven dips it is possible to calculate the NH/AV ratio in order to infer the composition of the obscuring material. In 5/27 stars with optical accretion bursts, we observe soft X-ray emission during the bursts that we associate to the emission of accreting gas. It is not surprising that these properties are not observed in all the stars with dips and bursts since favorable geometric configurations are required. The observed variable absorption during the dips is mainly due to dust-free material in accretion streams. In stars with accretion bursts we observe in average a larger soft X-ray spectral component not observed in non accreting stars. This indicates that this soft X-ray emission arises from the accretion shocks.

  19. A common stochastic process rules gamma-ray burst prompt emission and X-ray flares

    CERN Document Server

    Guidorzi, C; Frontera, F; Margutti, R; Baldeschi, A; Amati, L

    2015-01-01

    Prompt gamma-ray and early X-ray afterglow emission in gamma-ray bursts (GRBs) are characterized by a bursty behavior and are often interspersed with long quiescent times. There is compelling evidence that X-ray flares are linked to prompt gamma-rays. However, the physical mechanism that leads to the complex temporal distribution of gamma-ray pulses and X-ray flares is not understood. Here we show that the waiting time distribution (WTD) of pulses and flares exhibits a power-law tail extending over 4 decades with index ~2 and can be the manifestation of a common time-dependent Poisson process. This result is robust and is obtained on different catalogs. Surprisingly, GRBs with many (>=8) gamma-ray pulses are very unlikely to be accompanied by X-ray flares after the end of the prompt emission (3.1 sigma Gaussian confidence). These results are consistent with a simple interpretation: an hyperaccreting disk breaks up into one or a few groups of fragments, each of which is independently accreted with the same pro...

  20. Ionospheric Effects of X-Ray Solar Bursts in the Brazilian Sector

    Science.gov (United States)

    Becker-Guedes, F.; Takahashi, H.; Costa, J. E.; Otsuka, Y.

    2011-12-01

    When the solar X-ray flux in the interplanetary medium reaches values above a certain threshold, some undesired effects affecting radio communications are expected. Basically, the magnitudes of these effects depend on the X-ray peak brightness and duration, which drive the intensity of the ionosphere response when the associated electromagnetic wave hit the sunlit side of the Earth atmosphere. An important aspect defining the severity of damages to HF radio communications and LF navigation signals in a certain area is the local time when each event takes place. In order to create more accurate warnings referred to possible radio signal loss or degradation in the Brazilian sector, we analyze TEC maps obtained by a GPS network, formed by dual-frequency receivers spread all over the country, to observe ionospheric local changes during several X-ray events in the 0.1-0.8 nm range measured by GOES satellite. Considering the duration, peak brightness, and local time of the events, the final purpose of this study is to understand and predict the degree of changes suffered by the ionosphere during these X-ray bursts. We intend using these results to create a radio blackout warning product to be offered by the Brazilian space weather program named EMBRACE (Estudo e Monitoramento BRAsileiro do Clima Espacial): Brazilian Monitoring and Study of Space Weather.

  1. Bounds on Compactness for LMXB Neutron Stars from X-ray Burst Oscillations

    CERN Document Server

    Nath, N R; Swank, J H; Nath, Nitya; Strohmayer, Tod E.; Swank, Jean H.

    2001-01-01

    We have modelled X-ray burst oscillations observed with the Rossi X-ray Timing Explorer (RXTE) from two low mass X-ray binaries (LMXB): 4U 1636-53 with a frequency of 580 Hz, and 4U 1728-34 at a frequency of 363 Hz. We have computed least squares fits to the oscillations observed during the rising phase of bursts using a model which includes emission from either a single circular hot spot or a pair of circular antipodal hot spots on the surface of a neutron star. We model the spreading of the thermonuclear hot spots by assuming that the hot spot angular size grows linearly with time. We calculate the flux as a function of rotational phase from the hot spots and take into account photon deflection in the relativistic gravitational field of the neutron star assuming the exterior spacetime is the Schwarzschild metric. We find acceptable fits with our model and we use these to place constraints on the compactness of the neutron stars in these sources. For 4U 1636-53, in which detection of a 290 Hz sub-harmonic su...

  2. The Early X-ray Afterglows of Optically Bright and Dark Gamma-Ray Bursts

    Institute of Scientific and Technical Information of China (English)

    Yi-Qing Lin

    2006-01-01

    A systematic study on the early X-ray afterglows of both optically bright and dark gamma-ray bursts (B-GRBs and D-GRBs) observed by Swift is presented. Our sample includes 25 GRBs of which 13 are B-GRBs and 12 are D-GRBs. Our results show that the distributions of the X-ray afterglow fluxes (Fx), the gamma-ray fluxes (Sγ), and the ratio (Rγ,X) are similar for the two kinds of GRBs, that any observed differences should be simply statistical fluctuation. These results indicate that the progenitors of the two kinds of GRBs are of the same population with comparable total energies of explosion. The suppression of optical emission in the D-GRBs should result from circumburst but not from their central engine.

  3. X-ray flares of γ-ray bursts: Quakes of solid quark stars?

    Institute of Scientific and Technical Information of China (English)

    XU RenXin; LIANG EnWei

    2009-01-01

    A star-quake model is proposed to understand X-ray flares of both long and short γ-ray bursts (GRBs) in a solid quark star regime. Two kinds of central engines for GRBs are available if pulsar-like stars are actually (solid) quark stars, I.e., the SNE-type GRBs and the SGR-type GRBs. It is found that a quark star could be solidified about 103 to 106 s later after its birth if the critical temperature of phase transi-tion is a few Metga-electron-volts, and then s new source of free energy (I.e., elastic and gravitational ones, rather than rotational or magnetic energy) could be possible to power GRB X-ray flares.

  4. X-ray flares of γ-ray bursts: Quakes of solid quark stars?

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A star-quake model is proposed to understand X-ray flares of both long and short γ-ray bursts (GRBs) in a solid quark star regime. Two kinds of central engines for GRBs are available if pulsar-like stars are actually (solid) quark stars, i.e., the SNE-type GRBs and the SGR-type GRBs. It is found that a quark star could be solidified about 103 to 106 s later after its birth if the critical temperature of phase transi- tion is a few Metga-electron-volts, and then a new source of free energy (i.e., elastic and gravitational ones, rather than rotational or magnetic energy) could be possible to power GRB X-ray flares.

  5. A bright thermonuclear X-ray burst simultaneously observed with Chandra and RXTE

    CERN Document Server

    Zand, J J M in t; Marshall, H L; Ballantyne, D R; Jonker, P G; Paerels, F B S; Palmer, D M; Patruno, A; Weinberg, N N

    2013-01-01

    The prototypical accretion-powered millisecond pulsar SAX J1808.4-3658 was observed simultaneously with Chandra-LETGS and RXTE-PCA near the peak of a transient outburst in November 2011. A single thermonuclear (type-I) burst was detected, the brightest yet observed by Chandra from any source, and the second-brightest observed by RXTE. We found no evidence for discrete spectral features during the burst; absorption edges have been predicted to be present in such bursts, but may require a greater degree of photospheric expansion than the rather moderate expansion seen in this event (a factor of a few). These observations provide a unique data set to study an X-ray burst over a broad bandpass and at high spectral resolution (lambda/delta-lambda=200-400). We find a significant excess of photons at high and low energies compared to the standard black body spectrum. This excess is well described by a 20-fold increase of the persistent flux during the burst. We speculate that this results from burst photons being sc...

  6. The thermonuclear-flash model for X-ray burst sources - A new tool for observing neutron stars

    Science.gov (United States)

    Joss, P. C.

    1979-01-01

    The helium-flash model for X-ray burst sources, in which matter is presumed to accrete onto the surface of a neutron star, is discussed. Attention is given to the accretion process, nuclear burning, X-ray emission, and the energy released by convection as well as by radiative diffusion near the surface. The rise times of observed bursts, their spectral evolution, and the properties of the spectrally soft X-ray transients are considered. Problems in interpreting the continuum spectra are discussed, along with problems in the detection and measurement of line features in the spectra. Also considered are the ratio of time-averaged persistent luminosity to time-averaged burst luminosity, peak burst luminosities, and the possibility of detecting binary membership for burst sources.

  7. Single 100-terawatt attosecond X-ray light pulse generation

    CERN Document Server

    Xu, X R; Zhang, Y X; Lu, H Y; Zhang, H; Dromey, B; Zhu, S P; Zhou, C T; Zepf, M; He, X T

    2016-01-01

    The birth of attosecond light sources is expected to inspire a breakthrough in ultrafast optics, which may extend human real-time measurement and control techniques into atomic-scale electronic dynamics. For applications, it is essential to obtain a single attosecond pulse of high intensity, large photon energy and short duration. Here we show that single 100-terawatt attosecond X-ray light pulse with intensity ${1\\times10^{21}}\\textrm{W}/\\textrm{cm}^{{ 2}}$ and duration ${7.9} \\textrm{as}$ can be produced by intense laser irradiation on a capacitor-nanofoil target composed of two separate nanofoils. In the interaction, a strong electrostatic potential develops between two nanofoils, which drags electrons out of the second foil and piles them up in vacuum, forming an ultradense relativistic electron nanobunch. This nanobunch exists in only half a laser cycle and smears out in others, resulting in coherent synchrotron emission of a single pulse. Such an unprecedentedly giant attosecond X-ray pulse may bring us...

  8. Periodicity Analysis of X-ray Light Curves of SS 433

    Science.gov (United States)

    Jun-yi, Wang; Xiang-long, Lu; Qiu-wen, Zhao; Dian-qiao, Dong; Bao-qiang, Lao; Yang, Lu; Yan-heng, Wei; Xiao-cong, Wu; Tao, An

    2017-01-01

    SS 433 is sofar the unique X-ray binary that has the simultaneously detected orbital period, super-orbital period, and nutation period, as well as a bidirectional spiral jet. The study on its X-ray light variability is helpful for understanding the dynamic process of the system, and the correlations between the different wavebands. In this paper, two time-series analysis techniques, i.e., the Lomb-Scargle periodogram and weighted wavelet Z-transform, are employed to search for the periods in the Swift/BAT (Burst Alert Telescope) (15-50 keV) and RXTE/ASM (Rose X-ray Timing Explorer/All Sky Monitor) (1.5-3, 3- 4, and 5-12 keV) light curves of SS 433, and the Monte Carlo simulation is performed for the obtained periodical components. For the 15-50 keV energy band, five significant periodical components are detected, which are P1(∼6.29 d), P2 (∼6.54 d), P3 (∼13.08 d), P4 (∼81.50 d), and P5 (∼162.30 d). For the 3-5 and 5-12 keV energy bands, the periodical components P3 (∼13 d) and P5 (∼162 d) are detected in both energy bands. However, for the 1.5-3 keV energy band, no significant periodic signal is detected. P5 is the strongest periodic signal in the power spectrum for all the energy bands of 3-5, 5-12, and 15-50 keV, and it is consistent with the previous result obtained from the study of optical light curves. Furthermore, in combination with the radio spiral jet of SS 433, it is suggested that the X-ray and optical variability of P5 (∼162 d) is probably related to the precession of its relativistic jet. The high correlation between the X-ray and optical light curves may also imply that the X-ray and optical radiations are of the same physical origin. P3 shows a good agreement with the orbital period (∼13.07 d) obtained by the previous study, and P2 and P4 are respectively the high-frequency harmonics of P3 and P5. P1 is detected only in the power spectrum of the 15-50 keV energy band, and it is consistent with the nutation period of the system. As

  9. An impulsive solar burst observed in H-alpha, microwaves, and hard X-rays

    Science.gov (United States)

    Gary, D. E.; Tang, F.

    1985-01-01

    H-alpha, microwave, and hard X-ray observations of an unusually short duration impulsive spike burst are presented. The observations are analyzed, and it is found that the single spike is in fact composed of two separate acceleration episodes. The differences found in the time profiles for the two components stress the role of the decay rate and lead to a simple explanation for the often observed delay of the microwave peak. The approximate numbers of electrons responsible for the two types of emission are derived and compared.

  10. Classical novae and type I X-ray bursts: challenges for the 21st century

    CERN Document Server

    Parikh, A; Sala, G

    2014-01-01

    Classical nova explosions and type I X-ray bursts are the most frequent types of thermonuclear stellar explosions in the Galaxy. Both phenomena arise from thermonuclear ignition in the envelopes of accreting compact objects in close binary star systems. Detailed observations of these events have stimulated numerous studies in theoretical astrophysics and experimental nuclear physics. We discuss observational features of these phenomena and theoretical efforts to better understand the energy production and nucleosynthesis in these explosions. We also examine and summarize studies directed at identifying nuclear physics quantities with uncertainties that significantly affect model predictions.

  11. Possible hard X-ray shortages in bursts from KS 1731-260 and 4U 1705-44

    CERN Document Server

    Ji, Long; Chen, YuPeng; Zhang, Shuang-Nan; Kretschmar, Peter; Wang, Jian-Min; Li, Jian

    2014-01-01

    Aims: A hard X-ray shortage, implying the cooling of the corona, was observed during bursts of IGR J17473-272, 4U 1636-536, Aql X-1, and GS 1826-238. Apart from these four sources, we investigate here an atoll sample, in which the number of bursts for each source is larger than 5, to explore the possible additional hard X-ray shortage during {\\it Rossi X-ray timing explorer (RXTE)} era. Methods: According to the source catalog that shows type-I bursts, we analyzed all the available pointing observations of these sources carried out by the {\\it RXTE} proportional counter array (PCA). We grouped and combined the bursts according to their outburst states and searched for the possible hard X-ray shortage while bursting. Results: We found that the island states of KS 1731-260 and 4U 1705-44 show a hard X-ray shortage at significant levels of 4.5 and 4.7 $\\sigma$ and a systematic time lag of $0.9 \\pm 2.1$ s and $2.5 \\pm 2.0$ s with respect to the soft X-rays, respectively. While in their banana branches and other s...

  12. Type-I X-ray bursts reveal a fast co-evolving behavior of the corona in an X-ray binary

    CERN Document Server

    Chen, Yu-Peng; Zhang, Shuang-Nan; Li, Jian; Wang, Jian-Min

    2013-01-01

    The coronae in X-ray binaries (XRBs) still remain poorly understood, although they have been believed for a long time to play a key role in modeling the characteristic outbursts of XRBs. Type-I X-ray bursts, the thermonuclear flashes happening on the surface of a neutron star (NS), can be used as a probe to the innermost region of a NS XRB, where the corona is believed to be located very close to the NS. We report the discovery of a tiny life cycle of the corona that is promptly co-evolved with the type-I bursts superimposed on the outburst of the NS XRB IGR J17473$-$2721. This finding may serve as the first evidence of directly seeing the rapid disappearance and formation of a corona in an XRB with a cooling/heating timescale of less than a second, which can strongly constrain the accretion models in XRBs at work.

  13. X-ray detectors at the Linac Coherent Light Source.

    Science.gov (United States)

    Blaj, Gabriel; Caragiulo, Pietro; Carini, Gabriella; Carron, Sebastian; Dragone, Angelo; Freytag, Dietrich; Haller, Gunther; Hart, Philip; Hasi, Jasmine; Herbst, Ryan; Herrmann, Sven; Kenney, Chris; Markovic, Bojan; Nishimura, Kurtis; Osier, Shawn; Pines, Jack; Reese, Benjamin; Segal, Julie; Tomada, Astrid; Weaver, Matt

    2015-05-01

    Free-electron lasers (FELs) present new challenges for camera development compared with conventional light sources. At SLAC a variety of technologies are being used to match the demands of the Linac Coherent Light Source (LCLS) and to support a wide range of scientific applications. In this paper an overview of X-ray detector design requirements at FELs is presented and the various cameras in use at SLAC are described for the benefit of users planning experiments or analysts looking at data. Features and operation of the CSPAD camera, which is currently deployed at LCLS, are discussed, and the ePix family, a new generation of cameras under development at SLAC, is introduced.

  14. Periodicity Analysis of X-ray Light Curves of SS 433

    Science.gov (United States)

    Wang, J. Y.; Lu, X. L.; Zhao, Q. W.; Dong, D. Q.; Lao, B. Q.; Lu, Y.; Wei, Y. H.; Wu, X. C.; An, T.

    2016-03-01

    SS 433 is the only X-ray binary to date that was detected to have a pair of well-collimated jets, and its orbital period, super orbital period, and nutation period were all detected at the same time. The study on the periodic X-ray variabilities is helpful for understanding its dynamic process of the central engine and the correlation with other bands. In the present paper, two time series analysis techniques, Lomb-Scargle periodogram and weighted wavelet Z-transform, are employed to search for the periodicities from the Swift/BAT (Burst Alert Telescope)(15--50 keV) and RXTE/ASM (Rossi X-Ray Timing Explorer/All-Sky Monitor)(1.5--3, 3--5 and 5--12 keV) light curves of SS 433, and the Monte Carlo simulation is performed. For the 15--50 keV energy band, five significant periodic signals are detected, which are P_1(˜6.29 d), P_2 (˜6.54 d), P_3 (˜13.08 d), P_4 (˜81.50 d), and P_5 (˜162.30 d). For the 3--5 and 5--12 keV energy bands, periodic signals P_3 (˜13 d) and P_5 (˜162 d) are detected in both energy bands. However, for the 1.5--3 keV energy band, no significant periodic signal is detected. P_5 has the strongest periodic signal in the power spectrum for all the energy bands of 3--5, 5--12, and 15--50 keV, and it is consistent with that obtained by previous study in optical band. Further, due to the existence of relativistic radio jets, the X-ray and optical band variability of P_5 (˜162 d) is probably related to the precession of the relativistic jets. High coherence between X-ray and optical light curves may also imply that the X-ray and optical emissions are of the same physical origin. P_3 shows a good agreement with the orbital period (˜13.07 d) first obtained by previous study, and P_2 and P_4 are the high frequency harmonic components of P_3 and P_5, respectively. P_1 is detected from the power spectrum of 15--50 keV energy band only, and it is consistent with the systematic nutation period. As the power of energy band decreases (from hard X-ray to

  15. The cooling phase of Type-I X-ray bursts in 4U 1636-53

    CERN Document Server

    Zhang, Guobao; Altamirano, Diego

    2010-01-01

    Time-resolved spectra during the cooling phase of thermonuclear X-ray bursts in low-mass X-ray binaries (LMXBs) can be used to measure the radii and masses of neutron stars. We analyzed ~ 300 bursts of the LMXB 4U 1636-53 using data from the Rossi X-ray Timing Explorer. We divided the bursts in three groups, photospheric radius expansion (PRE), hard non-PRE and soft non-PRE bursts, based on the properties of the bursts and the state of the source at the time of the burst. For the three types of bursts, we found that the average relation between the bolometric flux and the temperature during the cooling phase of the bursts is significantly different from the canonical $F \\propto T^4$ relation that is expected if the apparent emitting area on the surface of the neutron star remains constant as the flux decreases during the decay of the bursts. We also found that a single power law cannot fit the average flux-temperature relation for any of the three types of bursts, and that the flux-temperature relation for th...

  16. Fast and slow magnetic deflagration fronts in Type I X-ray bursts

    CERN Document Server

    Cavecchi, Yuri; Watts, Anna L; Braithwaite, Jonathan

    2015-01-01

    Type I X-ray bursts are produced by thermonuclear runaways that develop on accreting neutron stars. Once one location ignites, the flame propagates across the surface of the star. Flame propagation is fundamental in order to understand burst properties like rise time and burst oscillations. Previous work quantified the effects of rotation on the front, showing that the flame propagates as a deflagration and that the front strongly resembles a hurricane. However the effect of magnetic fields was not investigated, despite the fact that magnetic fields strong enough to have an effect on the propagating flame are expected to be present on many bursters. In this paper we show how the coupling between fluid layers introduced by an initially vertical magnetic field plays a decisive role in determining the character of the fronts that are responsible for the Type I bursts. In particular, on a star spinning at 450 Hz (typical among the bursters) we test seed magnetic fields of $10^{7} - 10^{10}$ G and find that for th...

  17. The Post-Burst Awakening of the Anomalous X-ray Pulsar in Westerlund 1

    CERN Document Server

    Israel, G L; Dall'Osso, S; Muno, M P; Cummings, J; Perna, R; Stella, L

    2007-01-01

    On September 21, 2006, an intense (~10^39 erg/s) and short (20 ms) burst was detected by Swift BAT at a position consistent with that of the candidate Anomalous X-ray Pulsar, CXOU J164710.2-455216, discovered by Chandra in 2005. Swift follow-up observations began about 13 hours after the event and found the source at a 1-10keV flux level of about 4.5 x 10^-11 erg/s/cm^2, i.e. ~300 times brighter than measured 5 days earlier by XMM. We report the results obtained from Swift BAT observations of the burst and subsequent Swift XRT observations carried out during the first four months after the burst. These data are complemented with those from two XMM observations (carried out just before and after the BAT event) and four archival Chandra observations carried out between 2005 and 2007. We find a phase coherent solution for the source pulsations after the burst. The evolution of the pulse phase comprises an exponential component decaying with timescale of 1.4d which we interpret as the recovery stage following a l...

  18. The Low-High-Low Trend of Type III Radio Burst Starting Frequencies and Solar Flare Hard X-rays

    CERN Document Server

    Reid, Hamish A S; Kontar, Eduard P

    2014-01-01

    Using simultaneous X-ray and radio observations from solar flares, we investigate the link between the type III radio burst starting frequency and hard X-ray spectral index. For a proportion of events the relation derived between the starting height (frequency) of type III radio bursts and the electron beam velocity spectral index (deduced from X-rays) is used to infer the spatial properties (height and size) of the electron beam acceleration region. Both quantities can be related to the distance travelled before an electron beam becomes unstable to Langmuir waves. To obtain a list of suitable events we considered the RHESSI catalogue of X-ray flares and the Phoenix 2 catalogue of type III radio bursts. From the 200 events that showed both type III and X-ray signatures, we selected 30 events which had simultaneous emission in both wavelengths, good signal to noise in the X-ray domain and > 20 seconds duration. We find that > 50 % of the selected events show a good correlation between the starting frequencies ...

  19. X-ray bursts as a probe of the corona: the case of XRB 4U 1636-536

    CERN Document Server

    Ji, Long; Chen, YuPeng; Zhang, Shuang-Nan; Torres, Diego F; Kretschmar, Peter; Chernyakova, Masha; Li, Jian; Wang, Jian-Min

    2013-01-01

    To investigate the possible cooling of the corona by soft X-rays bursts, we have studied 114 bursts embedded in the known X-ray evolution of 4U 1636-536. We have grouped these bursts according to the ratio of the flux in the 1.5--12 keV band with respect to that in the 15--50 keV band, as monitored by RXTE/ASM and Swift/BAT, respectively. We have detected a shortage at hard X-rays while bursting. This provides hints for a corona cooling process driven by soft X-rays fed by the bursts that occurred on the surface of neutron star. The flux shortage at 30--50 keV has a time lag of 2.4$\\pm$1.5 seconds with respect to that at 2--10 keV, which is comparable to that of 0.7$\\pm$0.5 seconds reported in bursts of IGR 17473-2721. We comment on the possible origin of these phenomena and on the implications for the models on the location of the corona.

  20. INTEGRAL/JEM-X detection of a type-I X-ray burst from MAXI J1421-613

    DEFF Research Database (Denmark)

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

    2014-01-01

    During the Galactic Plane Scan performed on 2014 January 10, the two JEM-X instruments on-board INTEGRAL detected a type-I X-ray burst from the newly discovered X-ray transient MAXI J1421-613 (ATels #5750, #5751, #5759) over the 5 ks in which the source was in the instruments field of view. The o...... (translating into a luminosity of 1.3E37 erg/s at 8 kpc; 3-10 keV). We estimated a persistent flux outside the burst of 7E-10 erg/cm^2/s (3-25 keV). This detection reveals that MAXI J1421-613 is a newly discovered X-ray bursting transient source, thus hosting an accreting neutron star....

  1. Models for Flare Statistics and the Waiting-time Distribution of Solar Flare Hard X-ray Bursts

    Science.gov (United States)

    Wheatland, M. S.; Edney, S. D.

    1999-12-01

    In a previous study (Wheatland, Sturrock, McTiernan 1998), a waiting-time distribution was constructed for solar flare hard X-ray bursts observed by the ICE/ISEE-3 spacecraft. A comparison of the observed distribution with that of a time-dependent Poisson process indicated an overabundance of short waiting times (10~s -- 10~min), implying that the hard X-ray bursts are not independent events. Models for flare statistics assume or predict that flares are independent events -- in particular the avalanche model makes this specific prediction. The results of the previous study may be reconciled with the avalanche picture if individual flares produce several distinct bursts of hard X-ray emission. A detailed comparison of the avalanche model and the ICE/ISEE-3 waiting-time distribution is presented here.

  2. Magnetar-like X-Ray Bursts from a Rotation-powered Pulsar, PSR J1119-6127

    Science.gov (United States)

    Göğüş, Ersin; Lin, Lin; Kaneko, Yuki; Kouveliotou, Chryssa; Watts, Anna L.; Chakraborty, Manoneeta; Alpar, M. Ali; Huppenkothen, Daniela; Roberts, Oliver J.; Younes, George; van der Horst, Alexander J.

    2016-10-01

    Two energetic hard X-ray bursts from the rotation-powered pulsar PSR J1119-6127 recently triggered the Fermi and Swift space observatories. We have performed in-depth spectral and temporal analyses of these two events. Our extensive searches in both observatories’ data for lower luminosity bursts uncovered 10 additional events from the source. We report here on the timing and energetics of the 12 bursts from PSR J1119-6127 during its burst active phase on 2016 July 26 and 28. We also found a spectral softer X-ray flux enhancement in a post-burst episode, which shows evidence of cooling. Here we discuss the implications of these results on the nature of this unusual high-field radio pulsar, which firmly place it within the typical magnetar population.

  3. Determining Neutron Star Properties by Fitting Oblate Schwarzschild Waveforms To X-ray Burst Oscillations

    CERN Document Server

    Miller, M Coleman

    2014-01-01

    We have developed sophisticated new Bayesian analysis methods that enable us to estimate quickly the masses and radii of rapidly rotating, oblate neutron stars using the energy-resolved waveforms of their X-ray burst oscillations and to determine the uncertainties in these mass and radius estimates. We demonstrate these methods by generating and analyzing the energy-resolved burst oscillation waveforms that would be produced by a hot spot on various rapidly rotating, oblate stars, using the analytic implementation of the oblate-star Schwarzschild-spacetime (OS) approximation introduced by Morsink et al. 2007. In generating these synthetic data, we assume that 10$^6$ counts have been collected from the hot spot and that the background is $9\\times10^6$ counts. This produces a realistic modulation amplitude and a total number of counts comparable to the number that could be obtained by future space missions, by combining data from many bursts from a given star. We compute the joint posterior distribution of the ...

  4. On the average Gamma-Ray Burst X-ray flaring activity

    CERN Document Server

    Margutti, R; Duran, R Barniol; Guidorzi, C; Shen, R F; Chincarini, G

    2010-01-01

    Gamma-ray burst X-ray flares are believed to mark the late time activity of the central engine. We compute the temporal evolution of the average flare luminosity $$ in the common rest frame energy band of 44 GRBs taken from the large \\emph{Swift} 5-years data base. Our work highlights the importance of a proper consideration of the threshold of detection of flares against the contemporaneous continuous X-ray emission. In the time interval $30 \\rm{s}\\propto t^{-2.7\\pm 0.1}$; this implies that the flare isotropic energy scaling is $E_{\\rm{iso,flare}}\\propto t^{-1.7}$. The decay of the continuum underlying the flare emission closely tracks the average flare luminosity evolution, with a typical flare to steep-decay luminosity ratio which is $L_{\\rm{flare}}/L_{\\rm{steep}}=4.7$: this suggests that flares and continuum emission are deeply related to one another. We infer on the progenitor properties considering different models. According to the hyper-accreting black hole scenario, the average flare luminosity scali...

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

    CERN Document Server

    Suleimanov, V; Werner, K

    2010-01-01

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

  6. Deka-keV X-ray observations of solar bursts with WATCH/GRANAT: frequency distributions of burst parameters

    Science.gov (United States)

    Crosby, N.; Vilmer, N.; Lund, N.; Sunyaev, R.

    1998-06-01

    Solar flare observations in the deka-keV range are performed by the WATCH experiment on board the GRANAT satellite. The WATCH experiment is presented, including the energy calibration as applied in the present work. The creation of the solar burst catalogue covering two years of observation is described and some examples of solar observations are given. The estimated energy releases in the flares presented here are found to extend below the range of hard X-ray flares which were previously studied by ISEE-3 and HXRBS/SMM detectors. The X-ray emitting component cannot be exclusively explained by contributions from a thermal plasma around a few keV. Either a hotter component or a non-thermal population of particles must also be present to produce the observed deka-keV emission. The WATCH data furthermore shows that the relative contributions of these components may change during an event or from event to event and that the injection of energy contained in suprathermal electrons may occur throughout an event and not only during the rise phase. For the most energetic WATCH flares simultaneous observations performed by other experiments at higher energies further indicate that non-thermal emission can be observed as low as 10 keV. A statistical study is performed on the total WATCH solar database and frequency distributions are built on measured X-ray flare parameters. It is also investigated how the properties of these frequency distributions behave when subgroups of events defined by different ranges of parameters are considered. No correlation is found between the elapsed time interval between successive flares arising from the same active region and the peak intensity of the flare.

  7. Afterglow Observations Shed New Light on the Nature of X-ray Flashes

    CERN Document Server

    Granot, J; Perna, R; Granot, Jonathan; Ramirez-Ruiz, Enrico; Perna, Rosalba

    2005-01-01

    X-ray flashes (XRFs) and X-ray rich gamma-ray bursts (XRGRBs) share many observational characteristics with long duration GRBs, but the reason for which their prompt emission peaks at lower photon energies, $E_p$, is still under debate. Although many different models have been invoked in order to explain the lower $E_p$ values, their implications for the afterglow emission were not considered in most cases, mainly because observations of XRF afterglows have become available only recently. Here we examine the predictions of the various XRF models for the afterglow emission, and test them against the observations of XRF 030723 and XRGRB 041006, the events with the best monitored afterglow light curves in their respective class. We show that most existing XRF models are hard to reconcile with the observed afterglow light curves, which are very flat at early times. Such light curves are, however, naturally produced by a roughly uniform jet with relatively sharp edges that is viewed off-axis (i.e. from outside of ...

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

    CERN Document Server

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

    2014-01-01

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

  9. Large light X-ray optics: basic ideas and concepts

    Science.gov (United States)

    Citterio, O.; Ghigo, M.; Mazzoleni, F.; Pareschi, G.; Aschenbach, B.; Braeuninger, H.; Friedrich, P.; Hasinger, G.; Parodi, G.

    2004-01-01

    One of the main guidelines for future X-ray astronomy projects like, e.g., XEUS (ESA) and Generation-X (NASA) is to utilize grazing-incidence focusing optics with extremely large telescopes (several tens of m 2 at 1 keV), with a dramatic increase in collecting area of about two order of magnitude compared to the current X-ray telescopes. In order to avoid the problem of the source's confusion limit at low fluxes, the angular resolution required for these optics should be superb (a few arcsec at most). The enormous mirror dimensions together with the high imaging performances give rise to a number of manufacturing problems. It is basically impossible to realize so large mirrors from closed Wolter I shells which benefit from high mechanical stiffness. Instead the mirrors need to be formed as rectangular segments and a series of them will be assembled in a petal. Taking into account the realistic load capabilities of space launchers, to be able to put in orbit so large mirror modules the mass/geometric-area ratio of the optics should be very small. Finally, with a so large optics mass it would be very difficult to provide the electric power for an optics thermal active control, able to maintain the mirrors at the usual temperature of 20 °C. Therefore, very likely, the optics will instead operate in extreme thermal conditions, with the mirror temperature oscillating between -30 and -40 °C, that tends to exclude the epoxy replication approach (the mismatch between the CTE of the substrate and that of the resin would cause prohibitively large deformations of the mirror surface profiles). From these considerations light weight materials with high thermal-mechanical properties such as glass or ceramics become attractive to realize the mirrors of future Xray telescopes. In this paper, we will discuss a segments manufacturing method based on Borofloat TM glass. A series of finite element analysis concerning different aspects of the production, testing and integration of

  10. Implications of the Early X-Ray Afterglow Light Curves of Swift GRBs

    Energy Technology Data Exchange (ETDEWEB)

    Granot, Jonathan; /KIPAC, Menlo Park; Konigl, Arieh; /Chicago U., Astron. Astrophys. Ctr. /Chicago U., EFI; Piran, Tsvi; /Hebrew U.

    2006-01-17

    According to current models, gamma-ray bursts (GRBs) are produced when the energy carried by a relativistic outflow is dissipated and converted into radiation. The efficiency of this process, {epsilon}{sub {gamma}}, is one of the critical factors in any GRB model. The X-ray afterglow light curves of Swift GRBs show an early stage of flattish decay. This has been interpreted as reflecting energy injection. When combined with previous estimates, which have concluded that the kinetic energy of the late ({approx}> 10 hr) afterglow is comparable to the energy emitted in {gamma}-rays, this interpretation implies very high values of {epsilon}{sub {gamma}}, corresponding to {approx}> 90% of the initial energy being converted into {gamma}-rays. Such a high efficiency is hard to reconcile with most models, including in particular the popular internal-shocks model. We re-analyze the derivation of the kinetic energy from the afterglow X-ray flux and re-examine the resulting estimates of the efficiency. We confirm that, if the flattish decay arises from energy injection and the pre-Swift broad-band estimates of the kinetic energy are correct, then {epsilon}{sub {gamma}} {approx}> 0.9. We discuss various issues related to this result, including an alternative interpretation of the light curve in terms of a two-component outflow model, which we apply to the X-ray observations of GRB 050315. We point out, however, that another interpretation of the flattish decay--a variable X-ray afterglow efficiency (e.g., due to a time dependence of afterglow shock microphysical parameters)--is possible. We also show that direct estimates of the kinetic energy from the late X-ray afterglow flux are sensitive to the assumed values of the shock microphysical parameters and suggest that broad-band afterglow fits might have underestimated the kinetic energy (e.g., by overestimating the fraction of electrons that are accelerated to relativistic energies). Either one of these possibilities implies a

  11. QPOs from Random X-ray Bursts around Rotating Black Holes

    Science.gov (United States)

    Kukumura, Keigo; Kazanas, Demosthenes; Stephenson, Gordon

    2009-01-01

    We continue our earlier studies of quasi-periodic oscillations (QPOs) in the power spectra of accreting, rapidly-rotating black holes that originate from the geometric 'light echoes' of X-ray flares occurring within the black hole ergosphere. Our present work extends our previous treatment to three-dimensional photon emission and orbits to allow for arbitrary latitudes in the positions of the distant observers and the X-ray sources in place of the mainly equatorial positions and photon orbits of the earlier consideration. Following the trajectories of a large number of photons we calculate the response functions of a given geometry and use them to produce model light curves which we subsequently analyze to compute their power spectra and autocorrelation functions. In the case of an optically-thin environment, relevant to advection-dominated accretion flows, we consistently find QPOs at frequencies of order of approximately kHz for stellar-mass black hole candidates while order of approximately mHz for typical active galactic nuclei (approximately equal to 10(exp 7) solar mass) for a wide range of viewing angles (30 degrees to 80 degrees) from X-ray sources predominantly concentrated toward the equator within the ergosphere. As in out previous treatment, here too, the QPO signal is produced by the frame-dragging of the photons by the rapidly-rotating black hole, which results in photon 'bunches' separated by constant time-lags, the result of multiple photon orbits around the hole. Our model predicts for various source/observer configurations the robust presence of a new class of QPOs, which is inevitably generic to curved spacetime structure in rotating black hole systems.

  12. The cooling phase of Type I X-ray bursts observed with RXTE in 4U 1820–30 does not follow the canonical F / T4 relation

    NARCIS (Netherlands)

    Garc´ıa, Federico; Zhan, Guobao; M´endez, Mariano

    2013-01-01

    We analysed the complete set of bursts from the neutron-star low-mass X-ray binary 4U 1820–30 detected with the Rossi X-ray Timing Explorer (RXTE). We found that all are photospheric radius expansion bursts, and have similar duration, peak flux and fluence. From the analysis of time-resolved spectra

  13. Delays of optical bursts in simultaneous optical and X-ray observations of MXB 1636-53

    Science.gov (United States)

    Matsuoka, M.; Mitsuda, K.; Ohashi, T.; Inoue, H.; Koyama, K.; Makino, F.; Makishima, K.; Murakami, T.; Oda, M.; Ogawara, Y.

    1984-01-01

    Observations of simultaneous optical and X-ray bursts from 4U/MXB 1636-53 were made using the Hakucho burst monitor system and optical telescopes at the European Southern Observatory during 1979 and 1980. The six best cases among the 10 coinciding observations are analyzed in terms of a model in which the optical emission is the result of reprocessing of X-rays (through blackbody heating). From this analysis, the temperature (spatially averaged) and size of a reprocessor, and the smearing and delay of the optical bursts are obtained. For the maximum temperatures of the optical reprocessor, the values differ from burst to burst, ranging from about 3 x 10 to the 4th to about 10 to the 5th K. The present analysis suggests that the size of the reprocessor varies by a factor of a few. For the smearing of the optical bursts an upper limit of a few seconds is derived. The most important result of this analysis is that the delay times are not the same for all bursts. The possible constraints which these results put on a low-mass binary model of this burst source are discussed.

  14. NuSTAR observations of X-ray bursts from the magnetar 1E 1048.1–5937

    Energy Technology Data Exchange (ETDEWEB)

    An, Hongjun; Kaspi, Victoria M.; Archibald, Robert F. [Department of Physics, McGill University, Montreal, Quebec, H3A 2T8 (Canada); Beloborodov, Andrei M.; Gotthelf, Eric V.; Hailey, Charles J.; Mori, Kaya [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Kouveliotou, Chryssa [Space Science Office, ZP12, NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States); Boggs, Steven E.; Craig, William W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Christensen, Finn E. [DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Grefenstette, Brian W.; Harrison, Fiona A.; Madsen, Kristin K. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Zhang, William W. [Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2014-07-20

    We report the detection of eight bright X-ray bursts from the 6.5 s magnetar 1E 1048.1–5937, during a 2013 July observation campaign with the Nuclear Spectroscopic Telescope Array. We study the morphological and spectral properties of these bursts and their evolution with time. The bursts resulted in count rate increases by orders of magnitude, sometimes limited by the detector dead time, and showed blackbody spectra with kT ∼ 6-8 keV in the T{sub 90} duration of 1-4 s, similar to earlier bursts detected from the source. We find that the spectra during the tail of the bursts can be modeled with an absorbed blackbody with temperature decreasing with flux. The burst flux decays followed a power law of index 0.8-0.9. In the burst tail spectra, we detect a ∼13 keV emission feature, similar to those reported in previous bursts from this source as well as from other magnetars observed with the Rossi X-ray Timing Explorer. We explore possible origins of the spectral feature such as proton cyclotron emission, which implies a magnetic field strength of B ∼ 2 × 10{sup 15} G in the emission region. However, the consistency of the energy of the feature in different objects requires further explanation.

  15. NuSTAR Observations of X-Ray Bursts from the Magnetar 1E 1048.1-5937

    Science.gov (United States)

    An, Hongjun; Kaspi, Victoria M.; Beloborodov, Andrei M.; Kouveliotou, Chryssa; Archibald, Robert T.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Gotthelf, Eric V.; Stern, Daniel; Zhang, William W.

    2014-01-01

    We report the detection of eight bright X-ray bursts from the 6.5 s magnetar 1E 1048.1-5937, during a 2013 July observation campaign with the Nuclear Spectroscopic Telescope Array. We study the morphological and spectral properties of these bursts and their evolution with time. The bursts resulted in count rate increases by orders of magnitude, sometimes limited by the detector dead time, and showed blackbody spectra with kT is approx. 6-8 keV in the T90 duration of 1-4 s, similar to earlier bursts detected from the source. We find that the spectra during the tail of the bursts can be modeled with an absorbed blackbody with temperature decreasing with flux. The burst flux decays followed a power law of index 0.8-0.9. In the burst tail spectra, we detect a is approx. 13 keV emission feature, similar to those reported in previous bursts from this source as well as from other magnetars observed with the Rossi X-ray Timing Explorer.We explore possible origins of the spectral feature such as proton cyclotron emission, which implies a magnetic field strength of B is approx. 2×10(exp15) G in the emission region. However, the consistency of the energy of the feature in different objects requires further explanation.

  16. Implications of the Early X-Ray Afterglow Light Curves of Swift GRBs

    CERN Document Server

    Granot, J; Piran, T; Granot, Jonathan; Konigl, Arieh; Piran, Tsvi

    2006-01-01

    According to current models, gamma-ray bursts (GRBs) are produced when the energy carried by a relativistic outflow is dissipated and converted into radiation. The efficiency of this process, $\\epsilon_\\gamma$, is one of the critical factors in any GRB model. The X-ray afterglow light curves of Swift GRBs show an early stage of flat decay. This has been interpreted as reflecting energy injection. When combined with previous estimates, which have concluded that the kinetic energy of the late ($\\gtrsim 10$ hr) afterglow is comparable to the energy emitted in gamma-rays, this interpretation implies very high values of $\\epsilon_\\gamma \\gtrsim 0.9$. Such a high efficiency is hard to reconcile with most models, including in particular the popular internal-shocks model. We re-analyze the derivation of the kinetic energy from the afterglow X-ray flux and re-examine the resulting estimates of the efficiency. We confirm that, if the flatt decay arises from energy injection and the pre-Swift broad-band estimates of the...

  17. Tomographic analysis of the nonthermal x-ray bursts during disruption instability in the T-10 tokamak.

    Science.gov (United States)

    Savrukhin, P V; Ermolaeva, A I; Shestakov, E A; Khramenkov, A V

    2014-10-01

    Non-thermal x-ray radiation (Eγ up to 150 keV) is measured in the T-10 tokamaks during disruption instability using two sets of CdTe detectors (10 vertical and 7 horizontal view detectors). Special narrow cupper tubes collimators with lead screening and CdTe detectors integrated with amplifiers inside metallic containers provides enhanced spatial resolution of the system (r ∼ 3 cm) and assures protection from the parasitic hard x-ray (Eγ up to 1.5 MeV) and electromagnetic loads during disruption. Spatial localization of the nonthermal x-ray emissivity is reconstructed using tomographic Cormack technique with SVD matrix inversion. Analysis indicated appearance of an intensive non-thermal x-ray bursts during initial stage of the disruptions at high density. The bursts are characterized by repetitive spikes (2-3 kHz) of the x-ray emissivity from the plasma core area. Analysis indicated that the spikes can be connected with acceleration of the non-thermal electrons in enhanced longitudinal electric fields induced during energy quench at the disruption instability.

  18. NuSTAR Observations of X-ray Bursts from the Magnetar 1E 1048.1-5937

    DEFF Research Database (Denmark)

    An, Hongjun; Kaspi, Victoria M.; Beloborodov, Andrei M.

    2014-01-01

    with an absorbed blackbody with temperature decreasing with flux. The burst flux decays followed a power law of index 0.8-0.9. In the burst tail spectra, we detect a ~13 keV emission feature, similar to those reported in previous bursts from this source as well as from other magnetars observed with the Rossi X......-ray Timing Explorer. We explore possible origins of the spectral feature such as proton cyclotron emission, which implies a magnetic field strength of B ~ 2 × 1015 G in the emission region. However, the consistency of the energy of the feature in different objects requires further explanation....

  19. Helium in natal HII regions: the origin of the X-ray absorption in gamma-ray burst afterglows

    CERN Document Server

    Watson, Darach; Andersen, Anja C; Fynbo, Johan P U; Gorosabel, Javier; Hjorth, Jens; Jakobsson, Páll; Krühler, Thomas; Laursen, Peter; Leloudas, Giorgos; Malesani, Daniele

    2012-01-01

    Soft X-ray absorption in excess of Galactic is observed in the afterglows of most gamma-ray bursts (GRBs), but the correct solution to its origin has not been arrived at after more than a decade of work, preventing its use as a powerful diagnostic tool. We resolve this long-standing problem and find that He in the GRB's host HII region is responsible for most of the absorption. We show that the X-ray absorbing column density (N_Hx) is correlated with both the neutral gas column density and with the optical afterglow extinction (Av). This correlation explains the connection between dark bursts and bursts with high N_Hx values. From these correlations we exclude an origin of the X-ray absorption which is not related to the host galaxy, i.e. the intergalactic medium or intervening absorbers are not responsible. We find that the correlation with the dust column has a strong redshift evolution, whereas the correlation with the neutral gas does not. From this we conclude that the column density of the X-ray absorpt...

  20. Central compact objects, superslow X-ray pulsars, gamma-ray bursts: do they have anything to do with magnetars?

    CERN Document Server

    Tong, H

    2014-01-01

    Magnetars and many of the magnetar-related objects are summarized together and discussed. It is shown that there is an abuse of language in the use of "magnetar". Anomalous X-ray pulsars and soft gamma-ray repeaters are well-known magnetar candidates. The current so called anti-magnetar (for central compact objects), accreting magnetar (for superslow X-ray pulsars in high mass X-ray binaries), and millisecond magnetar (for the central engine of some gamma-ray bursts), they may not be real magnetars in present understandings. Their observational behaviors are not caused by the magnetic energy. Many of them are just neutron stars with strong surface dipole field. A neutron star plus strong dipole field is not a magnetar. The characteristic parameters of the neutron stars for the central engine of some gamma-ray bursts are atypical from the neutron stars in the Galaxy. Possible signature of magnetic activities in accreting systems are discussed, including repeated bursts and a hard X-ray tail. China's future har...

  1. Long Duration X-Ray Flash and X-Ray Rich Gamma Ray Burst from Low Mass Population III Star

    CERN Document Server

    Nakauchi, Daisuke; Sakamoto, Takanori; Kashiyama, Kazumi; Nakamura, Takashi

    2012-01-01

    Recent numerical simulations suggest that Population III (Pop III) stars are born with masses not larger than $\\sim 100M_\\odot$ but typically $\\sim 40M_{\\odot}$. We investigate whether such a low mass Pop III star can raise a Gamma Ray Burst (GRB) by considering the propagation of a jet, which is launched from the black hole, in the stellar envelope. It is generally believed that a super giant star is not an appropriate progenitor of a GRB, since the large envelope prevents the successful jet breakout. Especially for Pop III stars, the mass loss is not expected and the large hydrogen envelope is kept due to the low opacity envelope. We find, however, that those Pop III stars who end as blue super giants are compact enough for jets to break out the stellar envelopes successfully. We evaluate observational characters of Pop III GRBs and predict that Pop III GRBs have the duration of $\\sim 10^5$ sec in the observer frame and the peak luminosity of $\\sim 5 \\times 10^{50}{\\rm erg/sec}$. Moreover, assuming that the...

  2. Spectroscopic comparison between ultraluminous X-ray sources and magnetar bursts

    CERN Document Server

    Kajava, J J E

    2016-01-01

    Nearby galaxies host ultra-luminous X-ray sources (ULXs), whose nature remains largely unknown. Until the discovery of the first ULX pulsar, M82 X-2, the mechanism powering the large luminosities of most ULXs was thought to be super-Eddington accretion onto black holes. The ULX pulsar clearly indicates that this hypothesis is not universal, and the question arises if other ULXs are as well powered by accretion onto neutron stars. One possibility to have highly super-Eddington luminosity is by reducing the opacity by strong magnetic fields as in magnetars, as proposed for M82 X-2. To study the link between ULXs and magnetar bursts/flares, we have performed a comparative spectral study between these classes, which both emit at similar super-Eddington luminosities at around $L \\sim 10^{40}$ erg s$^{-1}$. We find that, when their spectra are fitted with dual thermal models, the long term spectral variations of ULXs are similar to short term spectral variability seen during magnetar flares. In both classes of sour...

  3. Puzzling thermonuclear burst behaviour from the transient low-mass X-ray binary IGR J17473-2721

    CERN Document Server

    Chenevez, J; Galloway, D K; Zand, J J M in 't; Kuulkers, E; Degenaar, N; Falanga, M; Del Monte, E; Evangelista, Y; Feroci, M; Costa, E

    2010-01-01

    We investigate the thermonuclear bursting behaviour of IGR J17473-2721, an X-ray transient that in 2008 underwent a six month long outburst, starting (unusually) with an X-ray burst. We detected a total of 57 thermonuclear bursts throughout the outburst with AGILE, Swift, RXTE, and INTEGRAL. The wide range of inferred accretion rates (between <1% and about 20% of the Eddington accretion rate m-dot_Edd) spanned during the outburst allows us to study changes in the nuclear burning processes and to identify up to seven different phases. The burst rate increased gradually with the accretion rate until it dropped (at a persistent flux corresponding to about 15% of m-dot_Edd) a few days before the outburst peak, after which bursts were not detected for a month. As the persistent emission subsequently decreased, the bursting activity resumed with a much lower rate than during the outburst rise. This hysteresis may arise from the thermal effect of the accretion on the surface nuclear burning processes, and the tim...

  4. Systematic Uncertainties in the Spectroscopic Measurements of Neutron-Star Masses and Radii from Thermonuclear X-ray Bursts. II. Eddington Limit

    OpenAIRE

    Guver, Tolga; Ozel, Feryal; Psaltis, Dimitrios

    2011-01-01

    Time resolved X-ray spectroscopy of thermonuclear bursts observed from low mass X-ray binaries offer a unique tool to measure neutron star masses and radii. In this paper, we continue our systematic analysis of all the X-ray bursts observed with RXTE from X-ray binaries. We determine the events which show clear evidence for photospheric radius expansion and measure the Eddington limits for these accreting neutron stars using the bolometric fluxes attained at the touchdown moments of each X-ra...

  5. X-Ray Reflection and an Exceptionally Long Thermonuclear Helium Burst from IGR J17062-6143

    Science.gov (United States)

    Keek, L.; Iwakiri, W.; Serino, M.; Ballantyne, D. R.; in’t Zand, J. J. M.; Strohmayer, T. E.

    2017-02-01

    Thermonuclear X-ray bursts from accreting neutron stars power brief but strong irradiation of their surroundings, providing a unique way to study accretion physics. We analyze MAXI/Gas Slit Camera and Swift/XRT spectra of a day-long flash observed from IGR J17062-6143 in 2015. It is a rare case of recurring bursts at a low accretion luminosity of 0.15% Eddington. Spectra from MAXI, Chandra, and NuSTAR observations taken between the 2015 burst and the previous one in 2012 are used to determine the accretion column. We find it to be consistent with the burst ignition column of 5 × 1010 g cm‑2, which indicates that it is likely powered by burning in a deep helium layer. The burst flux is observed for over a day, and decays as a straight power law: F ∝ t ‑1.15. The burst and persistent spectra are well described by thermal emission from the neutron star, Comptonization of this emission in a hot optically thin medium surrounding the star, and reflection off the photoionized accretion disk. At the burst peak, the Comptonized component disappears, when the burst may dissipate the Comptonizing gas, and it returns in the burst tail. The reflection signal suggests that the inner disk is truncated at ∼102 gravitational radii before the burst, but may move closer to the star during the burst. At the end of the burst, the flux drops below the burst cooling trend for 2 days, before returning to the pre-burst level.

  6. Testing the External Shock Model of Gamma-Ray Bursts using the Late-Time Simultaneous Optical and X-ray Afterglows

    CERN Document Server

    Urata, Yuji; Sakamoto, Takanori; Huang, Kuiyun; Zheng, Weikang; Sato, Goro; Aoki, Tsutomu; Deng, Jinsong; Ioka, Kunihito; Ip, WingHuen; Kawabata, Koji S; Lee, YiHsi; Liping, Xin; Mito, Hiroyuki; Miyata, Takashi; Nakada, Yoshikazu; Ohsugi, Takashi; Qiu, Yulei; Soyano, Takao; Tarusawa, Kenichi; Tashiro, Makoto; Uemura, Makoto; Wei, Jianyan; Yamashita, Takuya

    2007-01-01

    We study the ``normal'' decay phase of the X-ray afterglows of gamma-ray bursts (GRBs), which follows the shallow decay phase, using the events simultaneously observed in the R-band. The classical external shock model, in which neither the delayed energy injection nor time-dependency of shock micro-physics is considered, shows that the decay indices of the X-ray and R-band light curves, $\\alpha_{\\rm X}$ and $\\alpha_{\\rm O}$, obey a certain relation, and that in particular, $\\alpha_{\\rm O}-\\alpha_{\\rm X}$ should be larger than -1/4. For our selected 14 samples, we have found that 7 events violate the limit taking into account 1$\\sigma$ error, so that a fraction of events are outliers of the classical external shock model at the ``normal'' decay phase.

  7. Comparison of 30 THz impulsive burst time development to microwaves, H-alpha, EUV, and GOES soft X-rays

    CERN Document Server

    Miteva, R; Cabezas, D P; Cassiano, M M; Fernandes, L O T; Freeland, S L; Karlicky, M; Kerdraon, A; Kudaka, A S; Luoni, M L; Marcon, R; Raulin, J -P; Trottet, G; White, S M

    2015-01-01

    The recent discovery of impulsive solar burst emission in the 30 THz band is raising new interpretation challenges. One event associated with a GOES M2 class flare has been observed simultaneously in microwaves, H-alpha, EUV, and soft X-ray bands. Although these new observations confirm some features found in the two prior known events, they exhibit time profile structure discrepancies between 30 THz, microwaves, and hard X-rays (as inferred from the Neupert effect). These results suggest a more complex relationship between 30 THz emission and radiation produced at other wavelength ranges. The multiple frequency emissions in the impulsive phase are likely to be produced at a common flaring site lower in the chromosphere. The 30 THz burst emission may be either part of a nonthermal radiation mechanism or due to the rapid thermal response to a beam of high-energy particles bombarding the dense solar atmosphere.

  8. INTEGRAL detects an X-ray burst from SAX J1747.0-2853 with no detectable persistent emission

    DEFF Research Database (Denmark)

    Chenevez, Jérôme; Brandt, Søren Kristian; Kuulkers, Erik;

    2009-01-01

    A new season of observations for the INTEGRAL Galactic Bulge monitoring (see ATel #438) has started on 2009 Feb. 21st. During the latest observation between 2009 Feb 25 13:21 and 17:02 (UT) a type I X-ray burst from SAX J1747.0-2853 (1A 1743-288, aka GX .2-0.2) was detected by JEM-X at UT 14:50:5...

  9. The direct cooling tail method for X-ray burst analysis to constrain neutron star masses and radii

    Science.gov (United States)

    Suleimanov, Valery F.; Poutanen, Juri; Nättilä, Joonas; Kajava, Jari J. E.; Revnivtsev, Mikhail G.; Werner, Klaus

    2017-04-01

    Determining neutron star (NS) radii and masses can help to understand the properties of matter at supra-nuclear densities. Thermal emission during thermonuclear X-ray bursts from NSs in low-mass X-ray binaries provides a unique opportunity to study NS parameters, because of the high fluxes, large luminosity variations and the related changes in the spectral properties. The standard cooling tail method uses hot NS atmosphere models to convert the observed spectral evolution during cooling stages of X-ray bursts to the Eddington flux FEdd and the stellar angular size Ω. These are then translated to the constraints on the NS mass M and radius R. Here we present the improved, direct cooling tail method that generalizes the standard approach. First, we adjust the cooling tail method to account for the bolometric correction to the flux. Then, we fit the observed dependence of the blackbody normalization on flux with a theoretical model directly on the M-R plane by interpolating theoretical dependences to a given gravity, hence ensuring only weakly informative priors for M and R instead of FEdd and Ω. The direct cooling method is demonstrated using a photospheric radius expansion burst from SAX J1810.8-2609, which has happened when the system was in the hard state. Comparing to the standard cooling tail method, the confidence regions are shifted by 1σ towards larger radii, giving R = 11.5-13.0 km at M = 1.3-1.8 M⊙ for this NS.

  10. Bursting SN 1996cr's Bubble: Hydrodynamic and X-ray Modeling of its Circumstellar Medium

    CERN Document Server

    Dwarkadas, Vikram V; Bauer, Franz

    2010-01-01

    SN1996cr is one of the five closest SNe to explode in the past 30 years. Due to its fortuitous location in the Circinus Galaxy at ~ 3.7 Mpc, there is a wealth of recently acquired and serendipitous archival data available to piece together its evolution over the past decade, including a recent 485 ks Chandra HETG spectrum. In order to interpret this data, we have explored hydrodynamic simulations, followed by computations of simulated spectra and light curves under non-equilibrium ionization conditions, and directly compared them to the observations. Our simulated spectra manage to fit both the X-ray continuum and lines at 4 epochs satisfactorily, while our computed light curves are in good agreement with additional flux-monitoring data sets. These calculations allow us to infer the nature and structure of the circumstellar medium, the evolution of the SN shock wave, and the abundances of the ejecta and surrounding medium. The data imply that SN 1996cr exploded in a low-density medium before interacting with ...

  11. Deka-keV X-ray observations of solar bursts with WATCH/GRANAT: frequency distributions of burst parameters

    DEFF Research Database (Denmark)

    Crosby, N.; Vilmer, N.; Lund, Niels

    1998-01-01

    is described and some examples of solar observations are given. The estimated energy releases in the flares presented here are found to extend below the range of hard X-ray flares which were previously studied by ISEE-3 and HXRBS/SMM detectors. The X-ray emitting component cannot be exclusively explained...

  12. LONG-DURATION X-RAY FLASH AND X-RAY-RICH GAMMA-RAY BURSTS FROM LOW-MASS POPULATION III STARS

    Energy Technology Data Exchange (ETDEWEB)

    Nakauchi, Daisuke; Kashiyama, Kazumi; Nakamura, Takashi [Department of Physics, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502 (Japan); Suwa, Yudai [Yukawa Institute for Theoretical Physics, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502 (Japan); Sakamoto, Takanori [Center for Research and Exploration in Space Science and Technology (CRESST), NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2012-11-10

    Recent numerical simulations suggest that Population III (Pop III) stars were born with masses not larger than {approx}100 M {sub Sun} and typically {approx}40 M {sub Sun }. By self-consistently considering the jet generation and propagation in the envelope of these low-mass Pop III stars, we find that a Pop III blue supergiant star has the possibility of giving rise to a gamma-ray burst (GRB) even though it keeps a massive hydrogen envelope. We evaluate observational characteristics of Pop III GRBs and predict that Pop III GRBs have a duration of {approx}10{sup 5} s in the observer frame and a peak luminosity of {approx}5 Multiplication-Sign 10{sup 50} erg s{sup -1}. Assuming that the E {sub p}-L {sub p} (or E {sub p}-E {sub {gamma},iso}) correlation holds for Pop III GRBs, we find that the spectrum peak energy falls at approximately a few keV (or {approx}100 keV) in the observer frame. We discuss the detectability of Pop III GRBs by future satellite missions such as EXIST and Lobster. If the E {sub p}-E {sub {gamma},iso} correlation holds, we have the possibility to detect Pop III GRBs at z {approx} 9 as long-duration X-ray-rich GRBs by EXIST. Conversely, if the E {sub p}-L {sub p} correlation holds, we have the possibility to detect Pop III GRBs up to z {approx} 19 as long-duration X-ray flashes by Lobster.

  13. The optimal optical readout for the x-ray light valve—Document scanners

    OpenAIRE

    Oakham, P.; MacDougall, Robert D.; Rowlands, J. A.

    2008-01-01

    The x-ray light valve (XLV) is a novel, potentially low-cost, x-ray detector that converts an x-ray exposure into an optical image stored in a liquid crystal cell. This optical image is then transferred from the liquid crystal cell to a computer through an optical-to-digital imaging readout system. Previously, CCD-based cameras were used for the optical readout, but recently it was proposed that an inexpensive optical scanner, such as an office document scanner, is a better match to the optic...

  14. Omega Dante Soft X-Ray Power Diagnostic Component Calibration at the National Synchrotron Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, K; Weber, F; Dewald, E; Glenzer, S; Landen, O; Turner, R; Waide, P

    2004-04-15

    The Dante soft x-ray spectrometer installed on the Omega laser facility at the Laboratory for Laser Energetics, University of Rochester is a twelve-channel filter-edge defined x-ray power diagnostic. It is used to measure the absolute flux from direct drive, indirect drive (hohlraums) and other plasma sources. Calibration efforts using two beam lines, U3C (50eV-1keV) and X8A (1keV-6keV) at the National Synchrotron Light Source (NSLS) have been implemented to insure the accuracy of these measurements. We have calibrated vacuum x-ray diodes, mirrors and filters.

  15. Omega Dante soft x-ray power diagnostic component calibration at the National Synchrotron Light Source

    Science.gov (United States)

    Campbell, K. M.; Weber, F. A.; Dewald, E. L.; Glenzer, S. H.; Landen, O. L.; Turner, R. E.; Waide, P. A.

    2004-10-01

    The Dante soft x-ray spectrometer, installed on the Omega laser facility at the Laboratory for Laser Energetics, University of Rochester, is a 12-channel filter-edge defined soft x-ray power diagnostic. It is used to measure the spectrally resolved, absolute flux from direct drive, indirect drive (hohlraums) and other plasma sources. Dante component calibration efforts using two beam lines, U3C (50 eV-1 keV) and X8A (1-6 keV) at the National Synchrotron Light Source have been implemented to improve the accuracy of these measurements. We have calibrated metallic vacuum x-ray diodes, mirrors and filters.

  16. Structured x-ray beams from twisted electrons by inverse Compton scattering of laser light

    CERN Document Server

    Seipt, D; Fritzsche, S

    2014-01-01

    The inverse Compton scattering of laser light on high-energetic twisted electrons is investigated with the aim to construct spatially structured x-ray beams. In particular, we analyze how the properties of the twisted electrons, such as the topological charge and aperture angle of the electron Bessel beam, affects the energy and angular distribution of scattered x-rays. We show that with suitably chosen initial twisted electron states one can synthesize tailor-made x-ray beam profiles with a well-defined spatial structure, in a way not possible with ordinary plane-wave electron beams.

  17. The Coherent X-ray Imaging instrument at the Linac Coherent Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Mengning; Williams, Garth J.; Messerschmidt, Marc; Seibert, M. Marvin; Montanez, Paul A.; Hayes, Matt; Milathianaki, Despina; Aquila, Andrew; Hunter, Mark S.; Koglin, Jason E.; Schafer, Donald W.; Guillet, Serge; Busse, Armin; Bergan, Robert; Olson, William; Fox, Kay; Stewart, Nathaniel; Curtis, Robin; Miahnahri, Alireza Alan; Boutet, Sébastien, E-mail: sboutet@slac.stanford.edu [Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)

    2015-04-15

    Description of the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source. Recent scientific highlights illustrate the femtosecond crystallography, high power density and extreme matter capabilities of the CXI instrument. The Coherent X-ray Imaging (CXI) instrument specializes in hard X-ray, in-vacuum, high power density experiments in all areas of science. Two main sample chambers, one containing a 100 nm focus and one a 1 µm focus, are available, each with multiple diagnostics, sample injection, pump–probe and detector capabilities. The flexibility of CXI has enabled it to host a diverse range of experiments, from biological to extreme matter.

  18. The Soft X-ray Research instrument at the Linac Coherent Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Dakovski, Georgi L., E-mail: dakovski@slac.stanford.edu; Heimann, Philip; Holmes, Michael [Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Krupin, Oleg [Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); European XFEL, Notkestrasse 85, 22607 Hamburg (Germany); Minitti, Michael P.; Mitra, Ankush; Moeller, Stefan; Rowen, Michael; Schlotter, William F.; Turner, Joshua J. [Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)

    2015-04-02

    A description of the Soft X-ray Research instrument (SXR) at the Linac Coherent Light Source is given. Recent scientific highlights illustrate the wide variety of experiments and detectors that can be accommodated at SXR. The Soft X-ray Research instrument provides intense ultrashort X-ray pulses in the energy range 280–2000 eV. A diverse set of experimental stations may be installed to investigate a broad range of scientific topics such as ultrafast chemistry, highly correlated materials, magnetism, surface science, and matter under extreme conditions. A brief description of the main instrument components will be given, followed by some selected scientific highlights.

  19. Two new bursting neutron star low-mass X-ray binaries: Swift J185003.2-005627 and Swift J1922.7-1716

    CERN Document Server

    Degenaar, N; Altamirano, D; Wijnands, R

    2012-01-01

    We discuss the origin of two triggers of Swift's Burst Alert Telescope (BAT) that occurred in 2011. The triggers were identified with Swift J185003.2-005627, a previously unknown X-ray source, and the known but unclassified X-ray transient Swift J1922.7-1716. We investigate the BAT data and follow-up observations obtained with the X-ray and ultra-violet/optical telescopes to demonstrate that both triggers are consistent with thermonuclear X-ray bursts. This implies that both sources are neutron star low-mass X-ray binaries. The total duration of ~7 min and estimated energy output of ~(3-7)E39 erg, fall in between that of normal and intermediately long X-ray bursts. From the observed peaks of the X-ray bursts we estimate a distance of <3.7 kpc for Swift J185003.2-005627 and <4.8 kpc for Swift J1922.7-1716. We characterize the outburst and quiescent X-ray properties of the two sources. They have comparable average outburst luminosities of ~1E35-1E36 erg/s, and a quiescent luminosity equal to or lower than...

  20. X-ray Reflection and An Exceptionally Long Thermonuclear Helium Burst from IGR J17062-6143

    CERN Document Server

    Keek, L; Serino, M; Ballantyne, D R; Zand, J J M in 't; Strohmayer, T E

    2016-01-01

    Thermonuclear X-ray bursts from accreting neutron stars power brief but strong irradiation of their surroundings, providing a unique way to study accretion physics. We analyze MAXI/GSC and Swift/XRT spectra of an exceptionally long flash observed from IGR J17062-6143 in 2015. It is a rare case of recurring bursts at the low accretion luminosity of 0.15% Eddington. Spectra from MAXI, Chandra, and NuSTAR observations taken between the 2015 burst and the previous one in 2012 are used to determine the accretion column. We find it to be consistent with the burst ignition column of 5x10^10 g cm^-2, which indicates that it is likely powered by burning in a deep helium layer. The burst flux is observed for hours, and decays as a straight power law: F~t^-1.15. The burst and persistent spectra are well described by thermal emission from the neutron star, Comptonization of this emission in a hot optically thin medium surrounding the star, and reflection off the photoionized accretion disk. At the burst peak, the Compton...

  1. LFN, QPO and fractal dimension of X-ray light curves from black hole binaries

    Science.gov (United States)

    Prosvetov, Art; Grebenev, Sergey

    The origin of the low frequency noise (LFN) and quasi-periodic oscillations (QPO) observed in X-ray flux of Galactic black hole binaries is still not recognized in spite of multiple studies and attempts to model this phenomenon. There are known correlations between the QPO frequency, X-ray power density, X-ray flux and spectral state of the system, but there is no model that can do these dependences understandable. For the low frequency (~1 Hz) QPO we still have no even an idea capable to explain their production and don't know even what part of an accretion disc is responsible for them. Here we attempted to measure the fractal dimension of X-ray light curves of several black hole X-ray binaries and to study its correlation with the frequency of quasi periodic oscillations observed in their X-ray light-curves. The fractal dimension is a measure of the space-filling capacity of the light curves' profile. To measure the fractal dimension we used R/S method, which is fast enough and has good reputation in financial analytic and materials sciences. We found that if no QPO were observed in X-ray flux from the particular source, the fractal dimension is equal to the unique value which is independent on the source, its luminosity or its spectral state. On the other hand if QPO were detected in the flux, the fractal dimension deviated from its usual value. Also, we found a clear correlation between the QPO frequency and the fractal dimension of the emission. The relationship between these two parameters is solid but nonlinear. We believe that the analysis of X-ray light curves of black hole binaries using the fractal dimension has a good scientific potential and may provide an addition information on the geometry of accretion flow and fundamental physical parameters of the system.

  2. The direct cooling tail method for X-ray burst analysis to constrain neutron star masses and radii

    CERN Document Server

    Suleimanov, Valery F; Nättilä, Joonas; Kajava, Jari J E; Revnivtsev, Mikhail G; Werner, Klaus

    2016-01-01

    Determining neutron star (NS) radii and masses can help to understand the properties of matter at supra-nuclear densities. Thermal emission during thermonuclear X-ray bursts from NSs in low-mass X-ray binaries provides a unique opportunity to study NS parameters, because of the high fluxes, large luminosity variations and the related changes in the spectral properties. The standard cooling tail method uses hot NS atmosphere models to convert the observed spectral evolution during cooling stages of X-ray bursts to the Eddington flux F_Edd and the stellar angular size \\Omega. These are then translated to the constraints on the NS mass M and radius R. Here we present the improved, direct cooling tail method that generalises the standard approach. First, we adjust the cooling tail method to account for the bolometric correction to the flux. Then, we fit the observed dependence of the blackbody normalization on flux with a theoretical model directly on the M-R plane by interpolating theoretical dependences to a gi...

  3. On the connection of gamma-ray bursts and X-ray flashes in the BATSE and RHESSI databases

    Science.gov (United States)

    Řípa, J.; Mészáros, A.

    2016-12-01

    Classification of gamma-ray bursts (GRBs) into groups has been intensively studied by various statistical tests in previous years. It has been suggested that there was a distinct group of GRBs, beyond the long and short ones, with intermediate durations. However, such a group is not securely confirmed yet. Strangely, concerning the spectral hardness, the observations from the Swift and RHESSI satellites give different results. For the Swift/BAT database it is found that the intermediate-duration bursts might well be related to so-called X-ray flashes (XRFs). On the other hand, for the RHESSI dataset the intermediate-duration bursts seem to be spectrally too hard to be given by XRFs. The connection of the intermediate-duration bursts and XRFs for the BATSE database is not clear as well. The purpose of this article is to check the relation between XRFs and GRBs for the BATSE and RHESSI databases, respectively. We use an empirical definition of XRFs introduced by other authors earlier. For the RHESSI database we also use a transformation between the detected counts and the fluences based on the simulated detector response function. The purpose is to compare the hardnesses of GRBs with the definition of XRFs. There is a 1.3-4.2 % fraction of XRFs in the whole BATSE database. The vast majority of the BATSE short bursts are not XRFs because only 0.7-5.7 % of the short bursts can be given by XRFs. However, there is a large uncertainty in the fraction of XRFs among the intermediate-duration bursts. The fraction of 1-85 % of the BATSE intermediate-duration bursts can be related to XRFs. For the long bursts this fraction is between 1.0 % and 3.4 %. The uncertainties in these fractions are large, however it can be claimed that all BATSE intermediate-duration bursts cannot be given by XRFs. At least 79 % of RHESSI short bursts, at least 53 % of RHESSI intermediate-duration bursts, and at least 45 % of RHESSI long bursts should not be given by XRFs. A simulation of XRFs

  4. LIGHT SOURCE: TW Laser system for Thomson scattering X-ray light source at Tsinghua University

    Science.gov (United States)

    Yan, Li-Xm; Du, Ying-Chao; Du, Qiang; Li, Ren-Kai; Hua, Jian-Fei; Huang, Wen-Hui; Tang, Chuan-Xiang

    2009-06-01

    A TW (Tera Watt) laser system based on Ti:sapphire mainly for the Tsinghua Thomson scattering X-ray light source (TTX) is being built. Both UV (ultraviolet) laser pulse for driving the photocathode radio-frequency (RF) gun and the IR (infrared) laser pulse as the electron-beam-scattered-light are provided by the system. Efforts have also been made in laser pulse shaping and laser beam transport to optimize the high-brightness electron beam production by the photocathode RF gun.

  5. CORRELATION OF HARD X-RAY AND WHITE LIGHT EMISSION IN SOLAR FLARES

    Energy Technology Data Exchange (ETDEWEB)

    Kuhar, Matej; Krucker, Säm; Battaglia, Marina; Kleint, Lucia; Casadei, Diego [University of Applied Sciences and Arts Northwestern Switzerland, Bahnhofstrasse 6, 5210 Windisch (Switzerland); Oliveros, Juan Carlos Martinez; Hudson, Hugh S. [Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450 (United States)

    2016-01-01

    A statistical study of the correlation between hard X-ray and white light emission in solar flares is performed in order to search for a link between flare-accelerated electrons and white light formation. We analyze 43 flares spanning GOES classes M and X using observations from the Reuven Ramaty High Energy Solar Spectroscopic Imager and Helioseismic and Magnetic Imager. We calculate X-ray fluxes at 30 keV and white light fluxes at 6173 Å summed over the hard X-ray flare ribbons with an integration time of 45 s around the peak hard-X ray time. We find a good correlation between hard X-ray fluxes and excess white light fluxes, with a highest correlation coefficient of 0.68 for photons with energy of 30 keV. Assuming the thick target model, a similar correlation is found between the deposited power by flare-accelerated electrons and the white light fluxes. The correlation coefficient is found to be largest for energy deposition by electrons above ∼50 keV. At higher electron energies the correlation decreases gradually while a rapid decrease is seen if the energy provided by low-energy electrons is added. This suggests that flare-accelerated electrons of energy ∼50 keV are the main source for white light production.

  6. The time ending the shallow decay of the X-ray light curves of long GRBs

    CERN Document Server

    Nava, L; Ghirlanda, G; Cabrera, J I; Firmani, C; Avila-Reese, V

    2007-01-01

    The early X-ray light curve of Gamma Ray Bursts (GRBs) is complex, and shows a typical steep-flat-steep behaviour. The time T_a at which the flat (plateau) part ends may bear some important physical information, especially if it plays the same role of the so called jet break time t_jet. To this aim, stimulated by the recent analysis of Willingale et al., we have assembled a sample of GRBs of known redshifts, spectral parameters of the prompt emission, and T_a. By using T_a as a jet angle indicator, and then estimating the collimation corrected prompt energetics, we find a correlation between the latter quantity and the peak energy of the prompt emission. However, this correlation has a large dispersion, similar to the dispersion of the Amati correlation and it is not parallel to the Ghirlanda correlation. Furthermore, we show that the correlation itself results mainly from the dependence of the jet opening angle on the isotropic prompt energy, with the time T_a playing no role, contrary to what we find for th...

  7. Correlation of hard X-ray and white light emission in solar flares

    CERN Document Server

    Kuhar, Matej; Oliveros, Juan Carlos Martínez; Battaglia, Marina; Kleint, Lucia; Casadei, Diego; Hudson, Hugh S

    2015-01-01

    A statistical study of the correlation between hard X-ray and white light emission in solar flares is performed in order to search for a link between flare-accelerated electrons and white light formation. We analyze 43 flares spanning GOES classes M and X using observations from RHESSI (Reuven Ramaty High Energy Solar Spectroscopic Imager) and HMI (Helioseismic and Magnetic Imager). We calculate X-ray fluxes at 30 keV and white light fluxes at 6173 \\r{A} summed over the hard X-ray flare ribbons with an integration time of 45 seconds around the peak hard-X ray time. We find a good correlation between hard X-ray fluxes and excess white light fluxes, with a highest correlation coefficient of 0.68 for photons with energy of 30 keV. Assuming the thick target model, a similar correlation is found between the deposited power by flare-accelerated electrons and the white light fluxes. The correlation coefficient is found to be largest for energy deposition by electrons above ~50 keV. At higher electron energies the co...

  8. X-ray and optical bursts and flares in YSOs: results from a 5-day XMM-Newton monitoring campaign of L1551

    CERN Document Server

    Giardino, G; Micela, G; Reale, F; Sciortino, S; Silva, B

    2006-01-01

    We present the results of a five-day monitoring campaign with XMM-Newton of six X-ray bright young stellar objects (YSOs) in the star-forming complex L1551 in Taurus. All stars present significant variability on the five-day time scale. Modulation of the light curve on time scales comparable with the star's rotational period appeared to be present in the case of one weak-lined T Tauri star. Significant spectral variations between the 2000 and the 2004 observations were detected in the (unresolved) classical T Tauri binary system XZ Tau: a hot plasma component which was present in the X-ray spectrum in 2000 had significantly weakened in 2004. As XZ Tau N was undergoing a strong optical outburst in 2000, which had terminated since then, we speculate on the possible relationship between episodic, burst accretion, and X-ray heating. The transition object HL Tau underwent a strong flare with a complex temperature evolution, which is indicative of an event confined within a very large magnetic structure (few stella...

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

    CERN Document Server

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

    2016-01-01

    An X-ray flaring source was found near the galaxy NGC 4697. Two flares were seen, separated by four years. The flux increased by a factor of 90 on a timescale of about one minute. Both flares were very brief. There is no optical counterpart at the position of the flares, but if the source was at the distance of NGC 4697, the luminosities were 10^39 erg/s. Here we report the results of a search of archival X-ray data for 70 nearby galaxies looking for similar such flares. We found two flaring sources in globular clusters or ultra-compact dwarf companions of parent elliptical galaxies. One source flared once to a peak luminosity of 9 x 10^40 erg/s, while the other flared five times to 10^40 erg/s. All of the flare rise times were <1 minute, and they 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 gamma repeaters that hav...

  10. Generating Picosecond X-Ray Pulses with Beam Manipulation in Synchrotron Light Sources

    CERN Document Server

    Guo, Weiming; Harkay, Katherine C; Sajaev, Vadim; Yang Bing Xin

    2005-01-01

    The length of x-ray pulses generated by storage ring light sources is usually tens of picoseconds. For example, the value is 40 ps rms at the Advanced Photon Source (APS). Methods of x-ray pulse compression are of great interest at the APS. One possible method, per Zholents et al., is to tilt the electron bunch with deflecting rf cavities.* Alternately, we found that the electron bunch can develop a tilt after application of a vertical kick in the presence of nonzero chromaticity. After slicing, the x-ray pulse length is determined by the tilt angle and the vertical beam size. In principal, sub-picosecond pulses can be obtained at APS. To date we have observed 6 ps rms visible light pulses with a streak camera. Efforts are underway to attempt further compression of the x-ray pulse and to increase the brilliance. This method can be easily applied to any storage ring light sources to generate x-ray pulses up to two orders of magnitude shorter than the electron bunch length. In this paper, we will present the th...

  11. Nonthermal gamma-ray and X-ray flashes from shock breakout in gamma-ray bursts/supernovae

    CERN Document Server

    Wang, X Y; Waxman, E; Mészáros, P; Wang, Xiang-Yu; Li, Zhuo; Waxman, Eli; Meszaros, Peter

    2006-01-01

    Thermal X-ray emission which is simultaneous with the prompt gamma-rays has been detected for the first time from a supernova connected with a gamma-ray burst (GRB), namely GRB060218/SN2006aj. It has been interpreted as arising from the breakout of a mildly relativistic, radiation-dominated shock from a dense stellar wind surrounding the progenitor star. There is also evidence for the presence of a mildly relativistic ejecta in GRB980425/SN1998bw, based on its X-ray and radio afterglow. Here we study the process of repeated bulk Compton scatterings of shock breakout thermal photons by the mildly relativistic ejecta. During the shock breakout process, a fraction of the thermal photons would be repeatedly scattered between the pre-shock material and the shocked material as well as the mildly relativistic ejecta and, as a result, the thermal photons get boosted to increasingly higher energies. This bulk motion Comptonization mechanism will produce nonthermal gamma-ray and X-ray flashes, which could account for t...

  12. Determining neutron star masses and radii using energy-resolved waveforms of X-ray burst oscillations

    CERN Document Server

    Lo, Ka-Ho; Bhattacharyya, Sudip; Lamb, Frederick K

    2013-01-01

    Simultaneous, precise measurements of the mass $M$ and radius $R$ of neutron stars can yield uniquely valuable information about the still uncertain properties of cold matter at several times the density of nuclear matter. One method that could be used to measure $M$ and $R$ is to analyze the energy-dependent waveforms of the X-ray flux oscillations seen during some thermonuclear bursts from some neutron stars. These oscillations are thought to be produced by X-ray emission from hotter regions on the surface of the star that are rotating at or near the spin frequency of the star. Here we explore how well $M$ and $R$ could be determined by generating, and analyzing using Bayesian techniques, synthetic energy-resolved X-ray data that we produce assuming a future space mission having 2--30 keV energy coverage and an effective area of 10 m$^2$, such as the proposed \\textit{LOFT} or \\textit{AXTAR} missions. We find that if the hot spot is within 10$^\\circ$ of the rotation equator, both $M$ and $R$ can usually be d...

  13. ECLAIRs A microsatellite for the prompt optical and X-ray emission of Gamma-Ray Bursts

    CERN Document Server

    Barret, D

    2001-01-01

    The prompt gamma-ray emission of Gamma-Ray Bursts (GRBs) is currently interpreted in terms of radiation from electrons accelerated in internal shocks in a relativistic fireball. On the other hand, the origin of the prompt (and early afterglow) optical and X-ray emission is still debated, mostly because very few data exist for comparison with theoretical predictions. It is however commonly agreed that this emission hides important clues on the GRB physics and can be used to constrain the fireball parameters, the acceleration and emission processes and to probe the surroundings of the GRBs. ECLAIRs is a microsatellite devoted to the observation of the prompt optical and X-ray emission of GRBs. For about 150 GRBs/yr, independent of their duration, ECLAIRs will provide high time resolution high sensitivity spectral coverage from a few eV up to ~50 keV and localization to ~ 5'' in near real time. This capability is achieved by combining wide field optical and X-ray cameras sharing a common field of view (>~ 2.2 st...

  14. ECLAIRs A microsatellite to observe the prompt optical and X-ray emission of Gamma-Ray Bursts

    CERN Document Server

    Barret, D

    2003-01-01

    ECLAIRs is a French microsatellite devoted to the observation of the prompt optical and X-ray emission of GRBs. For about 100 GRBs/yr, independent of their duration, ECLAIRs will provide high time resolution high sensitivity spectral coverage from a few eV up to ~50 keV and localization to ~5 arcsec in near real time. This capability is achieved by combining wide field optical and X-ray cameras sharing a common field of view (~1/6th of the sky) with the coded-mask imaging telescopes providing the triggers and the coarse localizations of the bursts. Given the delays to start ground-based observations in response to a GRB trigger, ECLAIRs is unique in its ability to observe the early phases (the first ~20 sec) of all GRBs at optical wavelengths. Furthermore, with its mode of operation, ECLAIRs will enable to search for optical and X-ray precursors expected from theoretical grounds. Finally ECLAIRs is proposed to operate simultaneously with GLAST on a synchronous orbit. This combination will ensure broad band sp...

  15. Solving X-ray protein structures without a crystal: using X-ray Free Electron Laser, the fourth generation synchrotron light sources

    Institute of Scientific and Technical Information of China (English)

    Bo Huang

    2010-01-01

    @@ A synchrotron light source is a source of electromagnetic radiation artificially produced by specialized electron accelerators. Compared to the commonly used in-house X-ray sources, it is wavelength adjustable, much stronger and more focused. In the last two decades, synchrotron usage has become the mainstream for X-ray protein structure determination. Taking the advantage of micro-focus light beams of the third generation synchrotron, the size of a usable protein crystal for data collection decreases to micron level, which increases the rate of macromolecular structure determination to about 10 new protein data bank entries per day.

  16. The X-ray Correlation Spectroscopy instrument at the Linac Coherent Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Alonso-Mori, Roberto; Caronna, Chiara; Chollet, Matthieu; Curtis, Robin; Damiani, Daniel S.; Defever, Jim; Feng, Yiping; Flath, Daniel L.; Glownia, James M. [Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Lee, Sooheyong [Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Hasylab at DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Lemke, Henrik T.; Nelson, Silke; Bong, Eric; Sikorski, Marcin; Song, Sanghoon; Srinivasan, Venkat; Stefanescu, Daniel; Zhu, Diling; Robert, Aymeric, E-mail: aymeric@slac.stanford.edu [Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)

    2015-04-14

    A description of the X-ray Correlation Spectroscopy instrument at the Linac Coherent Light Source is presented. Recent highlights illustrate the coherence properties of the source as well as some recent dynamics measurements and future directions. The X-ray Correlation Spectroscopy instrument is dedicated to the study of dynamics in condensed matter systems using the unique coherence properties of free-electron lasers. It covers a photon energy range of 4–25 keV. The intrinsic temporal characteristics of the Linac Coherent Light Source, in particular the 120 Hz repetition rate, allow for the investigation of slow dynamics (milliseconds) by means of X-ray photon correlation spectroscopy. Double-pulse schemes could probe dynamics on the picosecond timescale. A description of the instrument capabilities and recent achievements is presented.

  17. Single particle imaging with soft x-rays at the Linac Coherent Light Source

    Science.gov (United States)

    Martin, Andrew V.; Andreasson, Jakob; Aquila, Andrew; Bajt, Saša; Barends, Thomas R. M.; Barthelmess, Miriam; Barty, Anton; Benner, W. Henry; Bostedt, Christoph; Bozek, John D.; Bucksbaum, Phillip; Caleman, Carl; Coppola, Nicola; DePonte, Daniel P.; Ekeberg, Tomas; Epp, Sascha W.; Erk, Benjamin; Farquar, George R.; Fleckenstein, Holger; Foucar, Lutz; Frank, Matthias; Gumprecht, Lars; Hampton, Christina Y.; Hantke, Max; Hartmann, Andreas; Hartmann, Elisabeth; Hartmann, Robert; Hau-Riege, Stephan P.; Hauser, Günther; Holl, Peter; Hoemke, André; Jönsson, Olof; Kassemeyer, Stephan; Kimmel, Nils; Kiskinova, Maya; Krasniqi, Faton; Krzywinski, Jacek; Liang, Mengning; Loh, Ne-Te Duane; Lomb, Lukas; Maia, Filipe R. N. C.; Marchesini, Stefano; Messerschmidt, Marc; Nass, Karol; Odic, Duško; Pedersoli, Emanuele; Reich, Christian; Rolles, Daniel; Rudek, Benedikt; Rudenko, Artem; Schmidt, Carlo; Schultz, Joachim; Seibert, M. Marvin; Shoeman, Robert L.; Sierra, Raymond G.; Soltau, Heike; Starodub, Dmitri; Steinbrener, Jan; Stellato, Francesco; Strüder, Lothar; Svenda, Martin; Tobias, Herbert; Ullrich, Joachim; Weidenspointner, Georg; Westphal, Daniel; White, Thomas A.; Williams, Garth; Hajdu, Janos; Schlichting, Ilme; Bogan, Michael J.; Chapman, Henry N.

    2011-06-01

    Results of coherent diffractive imaging experiments performed with soft X-rays (1-2 keV) at the Linac Coherent Light Source are presented. Both organic and inorganic nano-sized objects were injected into the XFEL beam as an aerosol focused with an aerodynamic lens. The high intensity and femtosecond duration of X-ray pulses produced by the Linac Coherent Light Source allow structural information to be recorded by X-ray diffraction before the particle is destroyed. Images were formed by using iterative methods to phase single shot diffraction patterns. Strategies for improving the reconstruction methods have been developed. This technique opens up exciting opportunities for biological imaging, allowing structure determination without freezing, staining or crystallization.

  18. The Definitive X-ray Light Curve of Swift J164449.3+573451

    CERN Document Server

    Mangano, V; Sbarufatti, B; Cannizzo, J K

    2015-01-01

    On March 28, 2011, the Swift Burst Alert Telescope triggered on an object that had no analog in over six years of Swift operations. Follow-up observations by the Swift X-ray Telescope (XRT) found a new, bright X-ray source covering 3 orders of magnitude in flux over the first few days, that was much more persistent (and variable) than gamma-ray burst afterglows. Ground-based spectroscopy found a redshift of 0.35, implying extremely high luminosity, with integrated isotropic-equivalent energy output in the X-ray band alone exceeding $10^{53}$ ergs in the first two weeks after discovery. Strong evidence for a collimated outflow or beamed emission was found. The observational properties of this object are unlike anything ever before observed. We interpret these unique properties as the result of emission from a relativistic jet produced in the aftermath of the tidal disruption of a main sequence star by a massive black hole (BH) in the center of the host galaxy. The source decayed slowly as the stellar remnants ...

  19. Hard X-ray bursts and DD microfusion neutrons from complex plasmas of vacuum discharge

    Indian Academy of Sciences (India)

    Yu K Kurilenkov; M Skowronek

    2003-12-01

    We create the random complex media of high-power density in low-energy nanosecond vacuum discharges. Hard X-ray emission efficiency, generation of energetic ions (∼ 1 MeV) and neutrons, trapping and releasing of fast ions and/or X-rays from interelectrode aerosol ensembles are the subject of our study. The neutrons from DD microfusion, as well as the modelling of some interstellar nuclear burning due to microexplosive nucleosynthesis are discussed. The value of neutron yield from DD fusion in interelectrode space varies and amounts to ∼ 105-107/4 per shot under ≈ 1 J of total energy deposited to create all discharge processes.

  20. X-ray and optical plateaus following the main bursts in GRBs and SNe Ⅱ-P: a hint about similar late injection behaviors?

    Institute of Scientific and Technical Information of China (English)

    Xiao-Hong Cui; Ren-Xin Xu

    2013-01-01

    We analyze the emission plateaus in the X-ray afterglow light curves of gamma-ray bursts (GRBs) and those in the optical light curves of type Ⅱ plateau supernovae (SNe Ⅱ-P) in order to study whether they have similar late energy injection behaviors.We show that correlations of bolometric energies (or luminosities) between the prompt explosions and the plateaus for the two phenomena are similar.The energy emitted by SNe Ⅱ-P are at the lower end of the range of possible energies for GRBs.The bolometric energies (or luminosities) in the prompt phase Eexpl (or Lexpl) and in the plateau phase Eplateau (or Lplateau) share relations of Eexpl ∝ E0.73±0.14plateau and Lexpl ∝ L~0.70plateau These results may indicate a similar late energy injection behavior that produces the observed plateaus in these two phenomena.

  1. Effects of a New Triple-alpha Reaction on X-ray Bursts of a Helium Accreting Neutron Star

    CERN Document Server

    Matsuo, Y; Noda, T; Saruwatari, M; Ono, M; Hashimoto, M; Fujimoto, M

    2011-01-01

    The effects of a new triple-$\\alpha$ reaction rate (OKK rate) on the helium flash of a helium accreting neutron star in a binary system have been investigated. Since the ignition points determine the properties of a thermonuclear flash of type I X-ray bursts, we examine the cases of different accretion rates, $dM/dt (\\dot{M})$, of helium from $3\\times10^{-10} M_{\\odot} \\rm yr^{-1}$ to $3\\times10^{-8} M_{\\odot} \\rm yr^{-1}$, which could cover the observed accretion rates. We find that for the cases of low accretion rates, nuclear burnings are ignited at the helium layers of rather low densities. As a consequence, helium deflagration would be triggered for all cases of lower accretion rate than $\\dot{M}\\simeq 3\\times10^{-8} M_{\\odot} \\rm yr^{-1}$. We find that OKK rate could be barely consistent with the available observations of the X-ray bursts on the helium accreting neutron star. However this coincidence is found to depend on the properties of crustal heating and the neutron star model.We suggest that OKK r...

  2. X-Rays from the Explosion Site: Fifteen Years of Light Curves of SN 1993J

    Science.gov (United States)

    Chandra, Poonam; Dwarkadas, Vikram V.; Ray, Alak; Immler, Stefan; Pooley, David

    2009-01-01

    We present a comprehensive analysis of the X-ray light curves of SN 1993J in a nearby galaxy M81. This is the only supernova other than SN 1987A, which is so extensively followed in the X-ray bands. Here we report on SN 1993J observations with the Chandra in the year 2005 and 2008, and Swift observations in 2005, 2006 and 2008. We combined these observations with all available archival data of SN 1993J, which includes ROSAT, ASCA, Chandra, and XMM-Newton, observations from 1993 April to 2006 August. In this paper we report the X-ray light curves of SN 1993J, extending up to fifteen years, in the soft (0.3-2.4 keV), hard (2-8 keV) and combined (0.3-8 keV) bands. The hard and soft-band fluxes decline at different rates initially, but after about 5 years they both undergo a t(sup -1) decline. The soft X-rays, which are initially low, start dominating after a few hundred days. We interpret that most of the emission below 8 keV is coming from the reverse shock which is radiative initially for around first 1000-2000 days and then turn into adiabatic shock. Our hydrodynamic simulation also confirms the reverse shock origin of the observed light curves. We also compare the Ha line luminosity of SN 1993J with its X-ray light curve and note that the Ha line luminosity has a fairly high fraction of the X-ray emission, indicating presence of clumps in the emitting plasma.

  3. On the Connection of Gamma-Ray Bursts and X-Ray Flashes in the BATSE and RHESSI Databases

    CERN Document Server

    Řípa, Jakub

    2016-01-01

    Classification of gamma-ray bursts (GRBs) into groups has been intensively studied by various statistical tests in previous years. It has been suggested that there was a distinct group of GRBs, beyond the long and short ones, with intermediate durations. However, such a group is not securely confirmed yet. Strangely, concerning the spectral hardness, the observations from the Swift and RHESSI satellites give different results. For the Swift/BAT database it is found that the intermediate-duration bursts might well be related to so-called X-ray flashes (XRFs). On the other hand, for the RHESSI dataset the intermediate-duration bursts seem to be spectrally too hard to be given by XRFs. The connection of the intermediate-duration bursts and XRFs for the BATSE database is not clear as well. The purpose of this article is to check the relation between XRFs and GRBs for the BATSE and RHESSI databases, respectively. We use an empirical definition of XRFs introduced by other authors earlier. For the RHESSI database we...

  4. Magnetar powered GRBs: Explaining the extended emission and X-ray plateau of short GRB light curves

    CERN Document Server

    Gompertz, B P; Wynn, G A

    2013-01-01

    Extended emission (EE) is a high-energy, early time rebrightening sometimes seen in the light curves of short gamma-ray bursts (GRBs). We present the first contiguous fits to the EE tail and the later X-ray plateau, unified within a single model. Our central engine is a magnetar surrounded by a fall-back accretion disc, formed by either the merger of two compact objects or the accretion-induced collapse of a white dwarf. During the EE phase, material is accelerated to super-Keplarian velocities and ejected from the system by the rapidly rotating ($P \\approx 1 - 10$ ms) and very strong ($10^{15}$ G) magnetic field in a process known as magnetic propellering. The X-ray plateau is modelled as magnetic dipole spin-down emission. We first explore the range of GRB phenomena that the propeller could potentially reproduce, using a series of template light curves to devise a classification scheme based on phenomology. We then obtain fits to the light curves of 9 GRBs with EE, simultaneously fitting both the propeller ...

  5. Scanning soft X-ray spectromicroscopy at the Pohang Light Source: commissioning results

    CERN Document Server

    Shin, H J

    2001-01-01

    A scanning spectromicroscopy facility has been installed at the undulator radiation beamline at the Pohang Light Source. The spectromicroscopy is operational in both the scanning transmission X-ray microscopy (STXM) and the scanning photoelectron microscopy (SPEM) modes. Currently, the measured X-ray spot size on the sample is about 0.4 mu m. The effective photon energy range of the STXM is 250-1000 eV and that of the SPEM is 400-1000 eV. The performance of the facility is presented in this report.

  6. At-wavelength metrology of x-ray optics at Diamond Light Source

    Science.gov (United States)

    Wang, Hongchang; Berujon, Sebastien; Sutter, John; Alcock, Simon G.; Sawhney, Kawal

    2014-09-01

    Modern, third-generation synchrotron radiation sources provide coherent and extremely bright beams of X-ray radiation. The successful exploitation of such beams depends to a significant extent on imperfections and misalignment of the optics employed on the beamlines. This issue becomes even more critical with the increasing use of active optics, and the desire to achieve diffraction-limited and coherence-preserving X-ray beams. In recent years, significant progress has been made to improve optic testing and optimization techniques, especially those using X-rays for so-called atwavelength metrology. These in-situ and at-wavelength metrology methods can be used not only to optimize the performance of X-ray optics, but also to correct and minimize the collective distortions of upstream beamline optics, including monochromators, and transmission windows. An overview of at-wavelength metrology techniques implemented at Diamond Light Source is presented, including grating interferometry and X-ray near-field speckle based techniques. Representative examples of the application of these techniques are also given, including in-situ and atwavelength calibration and optimization of: active, piezo bimorph mirrors; Kirkpatrick-Baez (KB) mirrors; and refractive optics such as compound refractive lenses.

  7. Burst and Persistent Emission Properties during the Recent Active Episode of the Anomalous X-Ray Pulsar 1E 1841-045

    Science.gov (United States)

    Lin, Lin; Kouveliotou, Chryssa; Gogus, Ersin; van der Horst, Alexander J.; Watts, Anna L.; Baring, Matthew G.; Kaneko, Yuki; Wijers, Ralph A. M. J.; Woods, Peter M.; Barthelmy, Scott; Burgess, J. Michael; Chaplin, Vandiver; Gehrels, Neil; Goldstein, Adam; Granot, Jonathan; Guiriec, Sylvain; Mcenery, Julie; Preece, Robert D.; Tierney, David; van der Klis, Michiel; von Kienlin, Andreas; Zhang, Shuang Nan

    2011-01-01

    SWift/BAT detected the first burst from 1E 1841-045 in May 2010 with intermittent burst activity recorded through at least July 2011. Here we present Swift and Fermi/GBM observations of this burst activity and search for correlated changes to the persistent X-ray emission of the source. The T90 durations of the bursts range between 18 - 140 ms, comparable to other magnetar burst durations, while the energy released in each burst ranges between (0.8-25) x 1038 erg, which is in the low side of SGR bursts. We find that the bursting activity did not have a significant effect on the persistent flux level of the source. We argue that the mechanism leading to this sporadic burst activity in IE 1841-045 might not involve large scale restructuring (either crustal or magnetospheric) as seen in other magnetar sources.

  8. Burst and Persistent Emission Properties during the Recent Active Episode of the Anomalous X-ray Pulsar 1E 1841-045

    CERN Document Server

    Lin, Lin; Gogus, Ersin; van der Horst, Alexander J; Watts, Anna L; Baring, Matthew G; Kaneko, Yuki; Wijers, Ralph A M J; Woods, Peter M; Barthelmy, Scott; Burgess, J Michael; Chaplin, Vandiver; Gehrels, Neil; Goldstein, Adam; Granot, Jonathan; Guiriec, Sylvain; Mcenery, Julie; Preece, Robert D; Tierney, David; van der Klis, Michiel; von Kienlin, Andreas; Zhang, Shuang Nan

    2011-01-01

    Swift/BAT detected the first burst from 1E 1841-045 in May 2010 with intermittent burst activity recorded through at least July 2011. Here we present Swift and Fermi/GBM observations of this burst activity and search for correlated changes to the persistent X-ray emission of the source. The T90 durations of the bursts range between 18-140 ms, comparable to other magnetar burst durations, while the energy released in each burst ranges between (0.8 - 25)E38 erg, which is in the low side of SGR bursts. We find that the bursting activity did not have a significant effect on the persistent flux level of the source. We argue that the mechanism leading to this sporadic burst activity in 1E 1841-045 might not involve large scale restructuring (either crustal or magnetospheric) as seen in other magnetar sources.

  9. Temperature Measurement during Thermonuclear X-ray Bursts with BeppoSAX

    CERN Document Server

    Beri, Aru; Orlandini, Mauro; Maitra, Chandreyee

    2015-01-01

    We have carried out a study of temperature evolution during thermonuclear bursts in LMXBs using broad band data from two instruments onboard BeppoSAX, the MECS and the PDS. However, instead of applying the standard technique of time resolved spectroscopy, we have determined the temperature in small time intervals using the ratio of count rates in the two instruments assuming a blackbody nature of burst emission and different interstellar absorption for different sources. Data from a total of twelve observations of six sources were analysed during which 22 bursts were detected. We have obtained temperatures as high as ~3.0 keV, even when there is no evidence of photospheric radius expansion. These high temperatures were observed in the sources within different broadband spectral states (soft and hard).

  10. The dependence of gamma-ray burst X-ray column densities on the model for Galactic hydrogen

    CERN Document Server

    Arcodia, Riccardo; Salvaterra, Ruben

    2016-01-01

    We study the X-ray absorption of a complete sample of 99 bright Swift gamma-ray bursts. Over the last few years, a strong correlation between the intrinsic X-ray absorbing column density (N_H(z)) and the redshift was found. This absorption excess in high-z GRBs is now thought to be due to the overlooked contribution of the absorption along the intergalactic medium, by means of both intervening objects and the diffuse warm-hot intergalactic medium along the line of sight. In this work we neglect the absorption along the IGM, because our purpose is to study the eventual effect of a radical change in the Galactic absorption model on the N_H(z) distribution. Therefore, we derive the intrinsic absorbing column densities using two different Galactic absorption models, the Leiden Argentine Bonn HI survey and the more recent model including molecular hydrogen. We find that, if on the one hand the new Galactic model considerably affects the single column density values, on the other hand there is no drastic change in ...

  11. Magnetically driven winds from differentially rotating neutron stars and X-ray afterglows of short gamma-ray bursts

    CERN Document Server

    Siegel, Daniel M; Rezzolla, Luciano

    2014-01-01

    Besides being among the most promising sources of gravitational waves, merging neutron-star binaries also represent a leading scenario to explain the phenomenology of short gamma-ray bursts (SGRBs). Recent observations have revealed a large subclass of SGRBs with roughly constant luminosity in their X-ray afterglows lasting 10-10^4 s. These features are generally taken as evidence for a long-lived central engine powered by the magnetic spin-down of a uniformly rotating magnetized object. We propose a different scenario in which the central engine powering the X-ray emission is a differentially rotating hypermassive neutron star (HMNS) that launches a quasi-isotropic and baryon-loaded wind driven by the magnetic field built-up through differential rotation. Our model is supported by long-term, three-dimensional, general-relativistic and ideal magnetohydrodynamic simulations showing that this isotropic emission is a very robust feature. For a given HMNS, the presence of a collimated component depends sensitivel...

  12. MAGNETICALLY DRIVEN WINDS FROM DIFFERENTIALLY ROTATING NEUTRON STARS AND X-RAY AFTERGLOWS OF SHORT GAMMA-RAY BURSTS

    Energy Technology Data Exchange (ETDEWEB)

    Siegel, Daniel M.; Ciolfi, Riccardo; Rezzolla, Luciano [Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, D-14476 Potsdam-Golm (Germany)

    2014-04-10

    Besides being among the most promising sources of gravitational waves, merging neutron star binaries also represent a leading scenario to explain the phenomenology of short gamma-ray bursts (SGRBs). Recent observations have revealed a large subclass of SGRBs with roughly constant luminosity in their X-ray afterglows, lasting 10-10{sup 4} s. These features are generally taken as evidence of a long-lived central engine powered by the magnetic spin-down of a uniformly rotating, magnetized object. We propose a different scenario in which the central engine powering the X-ray emission is a differentially rotating hypermassive neutron star (HMNS) that launches a quasi-isotropic and baryon-loaded wind driven by the magnetic field, which is built-up through differential rotation. Our model is supported by long-term, three-dimensional, general-relativistic, and ideal magnetohydrodynamic simulations, showing that this isotropic emission is a very robust feature. For a given HMNS, the presence of a collimated component depends sensitively on the initial magnetic field geometry, while the stationary electromagnetic luminosity depends only on the magnetic energy initially stored in the system. We show that our model is compatible with the observed timescales and luminosities and express the latter in terms of a simple scaling relation.

  13. Toward Femtosecond X-ray Spectroscopy at the Advanced Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Chong, Henry Herng Wei [Univ. of California, Berkeley, CA (United States)

    2004-01-01

    The realization of tunable, ultrashort pulse x-ray sources promises to open new venues of science and to shed new light on long-standing problems in condensed matter physics and chemistry. Fundamentally new information can now be accessed. Used in a pump-probe spectroscopy, ultrashort x-ray pulses provide a means to monitor atomic rearrangement and changes in electronic structure in condensed-matter and chemical systems on the physically-limiting time-scales of atomic motion. This opens the way for the study of fast structural dynamics and the role they play in phase transitions, chemical reactions and the emergence of exotic properties in materials with strongly interacting degrees of freedom. The ultrashort pulse x-ray source developed at the Advanced Light Source at the Lawrence Berkeley Laboratory is based on electron slicing in storage rings, and generates ~100 femtosecond pulses of synchrotron radiation spanning wavelengths from the far-infrared to the hard x-ray region of the electromagnetic spectrum. The tunability of the source allows for the adaptation of a broad range of static x-ray spectroscopies to useful pump-probe measurements. Initial experiments are attempted on transition metal complexes that exhibit relatively large structural changes upon photo-excitation and which have excited-state evolution determined by strongly interacting structural, electronic and magnetic degrees of freedom. Specifically, iron(II) complexes undergo a spin-crossover transition upon optical irradiation. The dynamics of the transition involve a metal-to-ligand charge transfer, a ΔS=2 change in magnetic moment and 10% bond dilation in the first coordination shell of the iron. Studies of the electronic dynamics are studied with time-resolved optical absorption measurements. The current progress of time-resolved structural studies to complete the picture of the spin-crossover transition is presented.

  14. Toward Femtosecond X-ray Spectroscopy at the Advanced Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Chong, Henry Herng Wei

    2004-04-16

    The realization of tunable, ultrashort pulse x-ray sources promises to open new venues of science and to shed new light on long-standing problems in condensed matter physics and chemistry. Fundamentally new information can now be accessed. Used in a pump-probe spectroscopy, ultrashort x-ray pulses provide a means to monitor atomic rearrangement and changes in electronic structure in condensed-matter and chemical systems on the physically-limiting time-scales of atomic motion. This opens the way for the study of fast structural dynamics and the role they play in phase transitions, chemical reactions and the emergence of exotic properties in materials with strongly interacting degrees of freedom. The ultrashort pulse x-ray source developed at the Advanced Light Source at the Lawrence Berkeley Laboratory is based on electron slicing in storage rings, and generates {approx}100 femtosecond pulses of synchrotron radiation spanning wavelengths from the far-infrared to the hard x-ray region of the electromagnetic spectrum. The tunability of the source allows for the adaptation of a broad range of static x-ray spectroscopies to useful pump-probe measurements. Initial experiments are attempted on transition metal complexes that exhibit relatively large structural changes upon photo-excitation and which have excited-state evolution determined by strongly interacting structural, electronic and magnetic degrees of freedom. Specifically, iron(II) complexes undergo a spin-crossover transition upon optical irradiation. The dynamics of the transition involve a metal-to-ligand charge transfer, a {Delta}S=2 change in magnetic moment and 10% bond dilation in the first coordination shell of the iron. Studies of the electronic dynamics are studied with time-resolved optical absorption measurements. The current progress of time-resolved structural studies to complete the picture of the spin-crossover transition is presented.

  15. High-resolution x-ray photoemission electron microscopy at the Advanced Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Stammler, T.; Anders, S.; Padmore, H.A. [Lawrence Berkeley National Lab., CA (United States); Stoehr, J. [IBM Almaden Research Center, San Jose, CA (United States); Scheinfein, M. [Arizona State Univ., Tempe, AZ (United States). Dept. of Physics and Astronomy; Ade, H. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Physics

    1998-12-31

    X-ray Photoemission Electron Microscopy (X-PEEM) is a full-field imaging technique where the sample is illuminated by an x-ray beam and the photoemitted electrons are imaged on a screen by means of an electron optics. It therefore combines two well-established materials analysis techniques--photoemission electron microscopy (PEEM) and x-ray spectroscopy such as near edge x-ray absorption fine structure (NEXAFS) spectroscopy. This combination opens a wide field of new applications in materials research and has proven to be a powerful tool to investigate simultaneously topological, elemental, chemical state, and magnetic properties of surfaces, thin films, and multilayers at high spatial resolution. A new X-PEEM installed at the bend magnet beamline 7.3.1.1 at the Advanced Light Source (ALS) is designed for a spatial resolution of 20 nm and is currently under commissioning. An overview of the ongoing experimental program using X-PEEM in the field of materials research at the ALS is given by elemental and chemical bonding contrast imaging of hard disk coatings and sliders, field emission studies on diamond films as possible candidates for field-emission flat-panel displays, and the study of dewetting and decomposition phenomena of thin polymer blends and bilayers.

  16. Supersoft X-ray Light Curve of RS Oph -- The White Dwarf Mass is Now Increasing

    CERN Document Server

    Kato, Mariko; Luna, Gerardo Juan Manuel

    2008-01-01

    The recurrent nova RS Ophiuchi, one of the candidates for Type Ia supernova progenitors, underwent the sixth recorded outburst in February 2006. We report a complete light curve of supersoft X-ray that is obtained for the first time. A numerical table of X-ray data is provided. The supersoft X-ray flux emerges about 30 days after the optical peak and continues until about 85 days when the optical flux shows the final decline. Such a long duration of supersoft X-ray phase can be naturally understood by our model in which a significant amount of helium layer piles up beneath the hydrogen burning zone during the outburst, suggesting that the white dwarf mass is effectively growing up. We have estimated the white dwarf mass in RS Oph to be 1.35 \\pm 0.01 M_\\sun and its growth rate to be about (0.5-1) \\times 10^{-7} M_\\sun yr^{-1} in average.

  17. National Synchrotron Light Source users manual: Guide to the VUV and x-ray beam lines

    Energy Technology Data Exchange (ETDEWEB)

    Gmuer, N.F.; White-DePace, S.M. (eds.)

    1987-08-01

    The success of the National Synchrotron Light Source in the years to come will be based, in large part, on the size of the users community and the diversity of the scientific disciplines represented by these users. In order to promote this philosophy, this National Synchrotron Light Source (NSLS) Users Manual: Guide to the VUV and X-Ray Beam Lines, has been published. This manual serves a number of purposes. In an effort to attract new research, it will present to the scientific community-at-large the current and projected architecture and capabilities of the various VUV and x-ray beam lines and storage rings. We anticipate that this publication will be updated periodically in order to keep pace with the constant changes at the NSLS.

  18. Quasi-Periodic Oscillations in the X-ray Light Curves of Blazars

    Indian Academy of Sciences (India)

    Paul J. Wiita

    2011-03-01

    Any quasi-periodic variations discovered in blazar light curves would contain important information on the location and nature of the processes within the emission regions. In non-blazar active galactic nuclei, particularly Seyfert galaxies, any such fluctuations are very likely to be associated with the accretion disks, but in blazars they would almost certainly have to emanate from jets. This brief review summarizes recent claims for the presence of quasi-periodic variability in the X-ray emission of several AGN, focusing on blazars. Although no individual claim of the presence of a QPO in AGN X-ray light curves is absolutely convincing, there are some good cases for the presence of QPOs, including the Narrow Line Seyfert 1 galaxy, RE J1034+396, the quasar, 3C 273 and the BL Lac, PKS 2155−304.

  19. The LOFT perspective on neutron star thermonuclear bursts: White paper in support of the mission concept of the large observatory for X-ray timing

    Energy Technology Data Exchange (ETDEWEB)

    in' t Zand, J. J.M. [SRON Netherlands Institute for Space Research, Utrecht (The Netherlands); Malone, Christopher M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Altamirano, D. [Univ. of Southampton, Southampton (United Kingdom); Ballantyne, D. R. [Georgia Inst. of Technology, Atlanta, GA (United States); Bhattacharyya, S. [Tata Institute of Fundamental Research, Mumbai (India); Brown, E. F. [Michigan State Univ., East Lansing, MI (United States); Cavecchi, Y. [Univ. of Amsterdam, Amsterdam (The Netherlands); Chakrabarty, D. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Chenevez, J. [Technical Univ. of Denmark, Lyngby (Denmark); Cumming, A. [McGill Univ., Montreal, QC (Canada); Degenaar, N. [Univ. of Cambridge, Cambridge (United Kingdom); Falanga, M. [International Space Science Institute, Bern (Switzerland); Galloway, D. K. [Monash Univ., VIC (Australia); Heger, A. [Monash Univ., VIC (Australia); Jose, J. [Univ. Politecnica de Catalunya, Barcelona (Spain); Institut d' Estudis Espacials de Catalunya, Barcelona (Spain); Keek, L. [Georgia Institute of Technology, Atlanta, GA (United States); Linares, M. [Univ. de La Laguna, Tenerife (Spain); Mahmoodifar, S. [Univ. of Maryland, College Park, MD (United States); Mendez, M. [Univ. of Groningen, Groningen (The Netherlands); Miller, M. C. [Univ. of Maryland, College Park, MD (United States); Paerels, F. B. S. [Columbia Astrophysics Lab., New York, NY (United States); Poutanen, J. [Univ. of Turku, Piikkio (Finland); Rozanska, A. [N. Copernicus Astronomical Center PAS, Warsaw (Poland); Schatz, H. [National Superconducting Cyclotron Laboratory at Michigan State University; Serino, M. [Institute of Physical and Chemical Research (RIKEN); Strohmayer, T. E. [NASA' s Goddard Space Flight Center, Greenbelt, MD (United States); Suleimanov, V. F. [Univ. Tubingen, Tubingen (Germany); Thielemann, F. -K. [Univ. Basel, Basel (Switzerland); Watts, A. L. [Univ. of Amsterdam, Amsterdam (The Netherlands); Weinberg, N. N. [Massachusetts Institute of Technology, Cambridge, MA (United States); Woosley, S. E. [Univ. of California, Santa Cruz, CA (United States); Yu, W. [Chinese Academy of Sciences (CAS), Shanghai (China); Zhang, S. [Institute of High-Energy Physics, Beijing (China); Zingale, M. [Stony Brook Univ., Stony Brook, NY (United States)

    2015-01-14

    The Large Area Detector (LAD) on the Large Observatory For X-ray Timing ( LOFT ), with a 8.5 m 2 photon- collecting area in the 2–30 keV bandpass at CCD-class spectral resolving power (λ/Δλ = 10 – 100), is designed for optimum performance on bright X-ray sources. Thus, it is well-suited to study thermonuclear X-ray bursts from Galactic neutron stars. These bursts will typically yield 2 x 105 photon detections per second in the LAD, which is at least 15 times more than with any other instrument past, current or anticipated. The Wide Field Monitor (WFM) foreseen for LOFT uniquely combines 2–50 keV imaging with large (30%) prompt sky coverage. This will enable the detection of tens of thousands of thermonuclear X-ray bursts during a 3-yr mission, including tens of superbursts. Both numbers are similar or more than the current database gathered in 50 years of X-ray astronomy.

  20. X-ray light valve (XLV): a novel detectors' technology for digital mammography

    Science.gov (United States)

    Marcovici, Sorin; Sukhovatkin, Vlad; Oakham, Peter

    2014-03-01

    A novel method, based on X-ray Light Valve (XLV) technology, is proposed for making good image quality yet inexpensive flat panel detectors for digital mammography. The digital mammography markets, particularly in the developing countries, demand quality machines at substantially lower prices than the ones available today. Continuous pressure is applied on x-ray detectors' manufacturers to reduce the flat panel detectors' prices. XLV presents a unique opportunity to achieve the needed price - performance characteristics for direct conversion, x-ray detectors. The XLV based detectors combine the proven, superior, spatial resolution of a-Se with the simplicity and low cost of liquid crystals and optical scanning. The x-ray quanta absorbed by a 200 μm a-Se produce electron - hole pairs that move under an electric field to the top and bottom of a-Se layer. This 2D charge distribution creates at the interface with the liquid crystals a continuous (analog) charge image corresponding to the impinging radiation's information. Under the influence of local electrical charges next to them, the liquid crystals twist proportionally to the charges and vary their light reflectivity. A scanning light source illuminates the liquid crystals while an associated, pixilated photo-detector, having a 42 μm pixel size, captures the light reflected by the liquid crystals and converts it in16 bit words that are transmitted to the machine for image processing and display. The paper will describe a novel XLV, 25 cm x 30 cm, flat panel detector structure and its underlying physics as well as its preliminary performance measured on several engineering prototypes. In particular, the paper will present the results of measuring XLV detectors' DQE, MTF, dynamic range, low contrast resolution and dynamic behavior. Finally, the paper will introduce the new, low cost, XLV detector based, digital mammography machine under development at XLV Diagnostics Inc.

  1. Proposal to DOE Basic Energy Sciences: Ultrafast X-ray science facility at the Advanced Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Schoenlein, Robert W.; Falcone, Roger W.; Abela, R.; Alivisatos, A.P.; Belkacem, A.; Berrah, N.; Bozek, J.; Bressler, C.; Cavalleri, A.; Chergui, M.; Glover, T.E.; Heimann, P.A.; Hepburn, J.; Larsson, J.; Lee, R.W.; McCusker, J.; Padmore, H.A.; Pattison, P.; Pratt, S.T.; Shank, C.V.; Wark, J.; Chang, Z.; Robin, D.W.; Schlueter, R.D.; Zholents, A.A.; Zolotorev, M.S.

    2001-12-12

    We propose to develop a true user facility for ultrafast x-ray science at the Advanced Light Source. This facility will be unique in the world, and will fill a critical need for the growing ultrafast x-ray research community. The development of this facility builds upon the expertise from long-standing research efforts in ultrafast x-ray spectroscopy and the development of femtosecond x-ray sources and techniques at both the Lawrence Berkeley National Laboratory and at U.C. Berkeley. In particular, the technical feasibility of a femtosecond x-ray beamline at the ALS has already been demonstrated, and existing ultrafast laser technology will enable such a beamline to operate near the practical limit for femtosecond x-ray flux and brightness from a 3rd generation synchrotron.

  2. Two types of softening detected in X-ray afterglows of Swift bursts: internal and external shock origins?

    CERN Document Server

    Qin, Y -P; Fan, J H; Lu, R -J

    2008-01-01

    The softening process observed in the steep decay phase of early X-ray afterglows of Swift bursts has remained a puzzle since its discovery. The softening process can also be observed in the later phase of the bursts and its cause has also been unknown. Recently, it was suggested that, influenced by the curvature effect, emission from high latitudes would shift the Band function spectrum from higher energy band to lower band, and this would give rise to the observed softening process accompanied by a steep decay of the flux density. The curvature effect scenario predicts that the terminating time of the softening process would be correlated with the duration of the process. In this paper, based on the data from the UNLV GRB group web-site, we found an obvious correlation between the two quantities. In addition, we found that the softening process can be divided into two classes: the early type softening ($t_{s,max}\\leq "4000"s$) and the late type softening ($t_{s,max} > "4000"s$). The two types of softening s...

  3. Evidence for a jet contribution to the optical/infrared light of neutron star X-ray binaries

    NARCIS (Netherlands)

    Russell, D.M.; Fender, R.P.; Jonker, P.G.

    2007-01-01

    Optical/near-infrared (optical/NIR, OIR) light from low-mass neutron star X-ray binaries (NSXBs) in outburst is traditionally thought to be thermal emission from the accretion disc. Here we present a comprehensive collection of quasi-simultaneous OIR and X-ray data from 19 low magnetic field NSXBs,

  4. Evaluating scintillator performance in time-resolved hard X-ray studies at synchrotron light sources

    Energy Technology Data Exchange (ETDEWEB)

    Rutherford, Michael E.; Chapman, David J.; White, Thomas G. [Imperial College London, London (United Kingdom); Drakopoulos, Michael [Diamond Light Source, I12 Joint Engineering, Environmental, Processing (JEEP) Beamline, Didcot, Oxfordshire (United Kingdom); Rack, Alexander [European Synchrotron Radiation Facility, Grenoble (France); Eakins, Daniel E., E-mail: d.eakins@imperial.ac.uk [Imperial College London, London (United Kingdom)

    2016-03-24

    Scintillator performance in time-resolved, hard, indirect detection X-ray studies on the sub-microsecond timescale at synchrotron light sources is reviewed, modelled and examined experimentally. LYSO:Ce is found to be the only commercially available crystal suitable for these experiments. The short pulse duration, small effective source size and high flux of synchrotron radiation is ideally suited for probing a wide range of transient deformation processes in materials under extreme conditions. In this paper, the challenges of high-resolution time-resolved indirect X-ray detection are reviewed in the context of dynamic synchrotron experiments. In particular, the discussion is targeted at two-dimensional integrating detector methods, such as those focused on dynamic radiography and diffraction experiments. The response of a scintillator to periodic synchrotron X-ray excitation is modelled and validated against experimental data collected at the Diamond Light Source (DLS) and European Synchrotron Radiation Facility (ESRF). An upper bound on the dynamic range accessible in a time-resolved experiment for a given bunch separation is calculated for a range of scintillators. New bunch structures are suggested for DLS and ESRF using the highest-performing commercially available crystal LYSO:Ce, allowing time-resolved experiments with an interframe time of 189 ns and a maximum dynamic range of 98 (6.6 bits)

  5. Tracking the motion of charges in a terahertz light field byfemtosecond X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Cavalleri, A.; Wall, S.; Simpson, C.; Statz, E.; Ward, D.W.; Nelson, K.A.; Rini, M.; Schoenlein, R.W.

    2006-07-01

    In condensed matter, light propagation near resonances isdescribed in terms of polaritons, electro-mechanical excitations in whichthe time-dependent electric field is coupled to the oscillation ofcharged masses. This description under pins our understanding of themacroscopic optical properties of solids, liquids and plasmas, as well asof their dispersion with frequency. In ferroelectric materials, terahertzradiation propagates by driving infrared-active lattice vibrations,resulting in phononpolariton waves. Electro-optic sampling withfemtosecond optical pulses can measure the time-dependent electricalpolarization, providing a phase-sensitive analogue to optical Ramanscattering. Here we use femtosecond time-resolved X-ray diffraction, aphase-sensitive analogue to inelastic X-ray scattering, to measure thecorresponding displacements of ions in ferroelectric lithium tantalate,LiTaO3. Amplitude and phase of all degrees of freedom in a light fieldare thus directly measured in the time domain. Notably, extension ofother X-ray techniques to the femtosecond timescale (for example,magnetic or anomalous scattering) would allow for studies in complexsystems, where electric fields couple to multiple degrees offreedom.

  6. A Superbend X-Ray Microdiffraction Beamline at the Advanced Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Tamura, N.; Kunz, M.; Chen, K.; Celestre, R.S.; MacDowell, A.A.; Warwick, T.

    2009-03-10

    Beamline 12.3.2 at the Advanced Light Source is a newly commissioned beamline dedicated to x-ray microdiffraction. It operates in both monochromatic and polychromatic radiation mode. The facility uses a superconducting bending magnet source to deliver an X-ray spectrum ranging from 5 to 22 keV. The beam is focused down to {approx} 1 um size at the sample position using a pair of elliptically bent Kirkpatrick-Baez mirrors enclosed in a vacuum box. The sample placed on high precision stages can be raster-scanned under the microbeam while a diffraction pattern is taken at each step. The arrays of diffraction patterns are then analyzed to derive distribution maps of phases, strain/stress and/or plastic deformation inside the sample.

  7. On the Anticorrelation Between Galaxy Light Concentration and X-ray-to-Optical Flux Ratio

    CERN Document Server

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

    2009-01-01

    Active Galactic Nuclei (AGN) play an important role in many aspects of the modern cosmology, and of particular interest is the issue of the interplay between AGN and their host galaxy. Using X-ray and optical data sets, we have explored the properties of a large sample of AGNs in the Subaru/XMM-Newton Deep Survey (SXDS) field, and studied their evolution in relation with the evolution of their host galaxy. We present here an anticorrelation between X-ray-to-optical flux ratio (X/O) and galaxy light concentration (C), which has been found for the first time and might suggest that early type galaxies, having poor matter supply to feed the AGN activity, have lower Eddington rates than those of late type galaxies.

  8. Luminescence imaging of water during irradiation of X-ray photons lower energy than Cerenkov- light threshold

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Seiichi; Koyama, Shuji; Komori, Masataka [Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine (Japan); Toshito, Toshiyuki [Department of Proton Therapy Physics, Nagoya Proton Therapy Center, Nagoya City West Medical Center (Japan)

    2016-10-01

    Luminescence imaging of water using X-ray photon irradiation at energy lower than maximum energy of ~200 keV is thought to be impossible because the secondary electrons produced in this energy range do not emit Cerenkov- light. Contrary to this consensus assumption, we show that the luminescence imaging of water can be achieved by X-ray irradiation at energy lower than 120 keV. We placed water phantoms on a table with a conventional X-ray imaging system, and luminescence images of these phantoms were measured with a high-sensitivity, cooled charge coupled device (CCD) camera during X-ray photon irradiation at energy below 120 keV. We also carried out such imaging of an acrylic block and plastic scintillator. The luminescence images of water phantoms taken during X-ray photon irradiation clearly showed X-ray photon distribution. The intensity of the X-ray photon images of the phantom increased almost proportionally to the number of X-ray irradiations. Lower-energy X-ray photon irradiation showed lower-intensity luminescence at the deeper parts of the phantom due to the higher X-ray absorption in the water phantom. Furthermore, lower-intensity luminescence also appeared at the deeper parts of the acrylic phantom due to its higher density than water. The intensity of the luminescence for water was 0.005% of that for plastic scintillator. Luminescence imaging of water during X-ray photon irradiation at energy lower than 120 keV was possible. This luminescence imaging method is promising for dose estimation in X-ray imaging systems.

  9. TW Laser system for Thomson scattering X-ray light source at Tsinghua University

    Institute of Scientific and Technical Information of China (English)

    YAN Li-Xin; DU Ying-Chao; DU Qiang; LI Ren-Kai; HUA Jian-Fei; HUANG Wen-Hui; TANG Chuan-Xiang

    2009-01-01

    A TW(Tera Watt)laser system based on Ti:sapphire mainly for the Tsinghua Thomson scattering X-ray light source(TTX)is being built.Both UV(ultraviolet)laser pulse for driving the photocathode radiofrequency(RF)gun and the IR(infrared)laser pulse as the electron-beam-scattered-light are provided by the system.Efforts have also been made in laser pulse shaping and laser beam transport to optimize the high-brightness electron beam production by the photocathode RF gun.

  10. THERMAL EMISSION IN THE EARLY X-RAY AFTERGLOWS OF GAMMA-RAY BURSTS: FOLLOWING THE PROMPT PHASE TO LATE TIMES

    Energy Technology Data Exchange (ETDEWEB)

    Friis, Mette [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, 107 Reykjavik (Iceland); Watson, Darach, E-mail: mef4@hi.is, E-mail: darach@dark-cosmology.dk [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark)

    2013-07-01

    Thermal radiation, peaking in soft X-rays, has now been detected in a handful of gamma-ray burst (GRB) afterglows and has to date been interpreted as shock break-out of the GRB's progenitor star. We present a search for thermal emission in the early X-ray afterglows of a sample of Swift bursts selected by their brightness in X-rays at early times. We identify a clear thermal component in eight GRBs and track the evolution. We show that at least some of the emission must come from highly relativistic material since two show an apparent super-luminal expansion of the thermal component. Furthermore, we determine very large luminosities and high temperatures for many of the components-too high to originate in a supernova shock break-out. Instead, we suggest that the component may be modeled as late photospheric emission from the jet, linking it to the apparently thermal component observed in the prompt emission of some GRBs at gamma-ray and hard X-ray energies. By comparing the parameters from the prompt emission and the early afterglow emission, we find that the results are compatible with the interpretation that we are observing the prompt quasi-thermal emission component in soft X-rays at a later point in its evolution.

  11. A Jet Break in the X-ray Light Curve of Short GRB 111020A: Implications for Energetics and Rates

    CERN Document Server

    Fong, Wen-fai; Margutti, Raffaella; Zauderer, B Ashley; Troja, Eleonora; Czekala, Ian; Chornock, Ryan; Gehrels, Neil; Sakamoto, Takanori; Fox, Derek B; Podsiadlowski, Philipp

    2012-01-01

    We present broad-band observations of the afterglow and environment of the short GRB 111020A. An extensive X-ray light curve from Swift/XRT, XMM-Newton and Chandra, spanning ~100 seconds to 10 days after the burst, reveals a significant break at t~2 days with pre- and post-break decline rates of alphaX,1 ~ -0.78 and alphaX,224.4 mag at 18 hours after the burst, and reveal a potential host galaxy with i~24.3 mag. The sub-arcsecond localization from Chandra provides a precise offset of 0.80"+/-0.11" (1-sigma) from this galaxy corresponding to an offset of 5-7 kpc for z=0.5-1.5. We find a high excess neutral Hydrogen column density of (7.5+/-2.0)e21 cm^(-2) (z=0). Our observations demonstrate that a growing fraction of short GRBs are collimated which may lead to a true event rate of >100-1000 Gpc^(-3) yr^(-1), in good agreement with the NS-NS merger rate of ~200-3000 Gpc^(-3) yr^(-1). This consistency is promising for coincident short GRB-gravitational wave searches in the forthcoming era of Advanced LIGO/VIRGO.

  12. The Coherent X-ray Imaging (CXI) Instrument at the Linac Coherent Light Source (LCLS)

    Energy Technology Data Exchange (ETDEWEB)

    Boutet, Sebastien; Williams, Garth J.; /SLAC

    2011-08-16

    The Linac Coherent Light Source (LCLS) has become the first ever operational hard X-ray Free Electron Laser in 2009. It will operate as a user facility capable of delivering unique research opportunities in multiple fields of science. The LCLS and the LCLS Ultrafast Science Instruments (LUSI) construction projects are developing instruments designed to make full use of the capabilities afforded by the LCLS beam. One such instrument is being designed to utilize the LCLS coherent beam to image with high resolution any sub-micron object. This instrument is called the Coherent X-ray Imaging (CXI) instrument. This instrument will provide a flexible optical system capable of tailoring key beam parameters for the users. A suite of shot-to-shot diagnostics will also be provided to characterize the beam on every pulse. The provided instrumentation will include multi-purpose sample environments, sample delivery and a custom detector capable of collecting 2D data at 120 Hz. In this article, the LCLS will be briefly introduced along with the technique of Coherent X-ray Diffractive Imaging (CXDI). A few examples of scientific opportunities using the CXI instrument will be described. Finally, the conceptual layout of the instrument will be presented along with a description of the key requirements for the overall system and specific devices required.

  13. NuSTAR OBSERVATION OF A TYPE I X-RAY BURST FROM GRS 1741.9-2853

    Energy Technology Data Exchange (ETDEWEB)

    Barrière, Nicolas M.; Krivonos, Roman; Tomsick, John A.; Boggs, Steven E.; Craig, William W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Bachetti, Matteo [Institut de Recherche en Astrophysique et Plantologie, UMR 5277, Toulouse (France); Chakrabarty, Deepto [MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Christensen, Finn E. [National Space Institute, Technical University of Denmark, Copenhagen (Denmark); Hailey, Charles J.; Mori, Kaya [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Harrison, Fiona A. [Cahill Center for Astronomy and Astrophysics, Caltech, Pasadena, CA 91125 (United States); Hong, Jaesub [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Zhang, William W., E-mail: barriere@ssl.berkeley.edu [X-ray Astrophysics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2015-02-01

    We report on two NuSTAR observations of GRS 1741.9-2853, a faint neutron star (NS) low-mass X-ray binary burster located 10' away from the Galactic center. NuSTAR detected the source serendipitously as it was emerging from quiescence: its luminosity was 6 × 10{sup 34} erg s{sup –1} on 2013 July 31 and 5 × 10{sup 35} erg s{sup –1} in a second observation on 2013 August 3. A bright, 800 s long, H-triggered mixed H/He thermonuclear Type I burst with mild photospheric radius expansion (PRE) was present during the second observation. Assuming that the luminosity during the PRE was at the Eddington level, an H mass fraction X = 0.7 in the atmosphere, and an NS mass M = 1.4 M {sub ☉}, we determine a new lower limit on the distance for this source of 6.3 ± 0.5 kpc. Combining with previous upper limits, this places GRS 1741.9-2853 at a distance of 7 kpc. Energy independent (achromatic) variability is observed during the cooling of the NS, which could result from the disturbance of the inner accretion disk by the burst. The large dynamic range of this burst reveals a long power-law decay tail. We also detect, at a 95.6% confidence level (1.7σ), a narrow absorption line at 5.46 ± 0.10 keV during the PRE phase of the burst, reminiscent of the detection by Waki et al. We propose that the line, if real, is formed in the wind above the photosphere of the NS by a resonant Kα transition from H-like Cr gravitationally redshifted by a factor 1 + z = 1.09, corresponding to a radius range of 29.0-41.4 km for a mass range of 1.4-2.0 M {sub ☉}.

  14. Modeling the X-ray light curves of Cygnus X-3. Possible role of the jet

    CERN Document Server

    Vilhu, Osmi

    2012-01-01

    Context: Physics behind the soft X-ray light curve asymmetries in Cygnus X-3, a well-known microquasar, was studied. AIMS: Observable effects of the jet close to the line-of-sight were investigated and interpreted within the frame of light curve physics. METHODS: The path of a hypothetical imprint of the jet, advected by the WR-wind, was computed and its crossing with the line-of-sight during the binary orbit determined. We explore the possibility that physically this 'imprint' is a formation of dense clumps triggered by jet bow shocks in the wind ("clumpy trail"). Models for X-ray continuum and emission line light curves were constructed using two absorbers: mass columns along the line-of-sight of i) the WR wind and ii) the clumpy trail, as seen from the compact star. These model light curves were compared with the observed ones from the RXTE/ASM (continuum) and Chandra/HETG (emission lines). Results: We show that the shapes of the Cygnus X-3 light curves can be explained by the two absorbers using the incli...

  15. NuSTAR observation of a Type I X-ray burst from GRS 1741.9-2853

    CERN Document Server

    Barrière, Nicolas M; Tomsick, John A; Bachetti, Matteo; Boggs, Steven E; Chakrabarty, Deepto; Christensen, Finn E; Craig, William W; Hailey, Charles J; Harrison, Fiona A; Hong, Jaesub; Mori, Kaya; Stern, Daniel; Zhang, William W

    2014-01-01

    We report on two NuSTAR observations of GRS 1741.9-2853, a faint neutron star low mass X-ray binary burster located 10' away from the Galactic center. NuSTAR detected the source serendipitously as it was emerging from quiescence: its luminosity was $6\\times 10^{34}$ erg~s$^{-1}$ on 2013 July 31, and $5\\times 10^{35}$ erg~s$^{-1}$ in a second observation on 2013 August 3. A bright, 800-s long, H-triggered mixed H/He thermonuclear Type I burst with mild photospheric radius expansion (PRE) was present during the second observation. Assuming that the luminosity during the PRE was at the Eddington level, a H mass fraction $X=0.7$ in the atmosphere, and a neutron star mass $M=1.4 M_{\\odot}$, we determine a new lower limit on the distance for this source of $6.3 \\pm 0.5$ kpc. Combining with previous upper limits, this places GRS 1741.9-2853 at a distance of 7 kpc. Energy independent (achromatic) variability is observed during the cooling of the neutron star, which could result from the disturbance of the inner accre...

  16. Flame Propagation on the Surfaces of Rapidly Rotating Neutron Stars during Type I X-ray Bursts

    CERN Document Server

    Cavecchi, Yuri; Braithwaite, Jonathan; Levin, Yuri

    2012-01-01

    We present the first vertically resolved hydrodynamic simulations of a laterally propagating, deflagrating flame in the thin helium ocean of a rotating accreting neutron star. We use a new hydrodynamics solver tailored to deal with the large discrepancy in horizontal and vertical length scales typical of neutron star oceans, and which filters out sound waves that would otherwise limit our timesteps. We find that the flame moves horizontally with velocities of order $10^5$ cm s$^{-1}$, crossing the ocean in few seconds, broadly consistent with the rise times of Type I X-ray bursts. We address the open question of what drives flame propagation, and find that heat is transported from burning to unburnt fuel by a combination of top-to-bottom conduction and mixing driven by a baroclinic instability. The speed of the flame propagation is therefore a sensitive function of the ocean conductivity and spin: we explore this dependence for an astrophysically relevant range of parameters and find that in general flame pro...

  17. Observational Signatures of High-Energy Emission during the Shallow Decay Phase of Gamma-Ray Burst X-Ray Afterglows

    Science.gov (United States)

    Yu, Y. W.; Liu, X. W.; Dai, Z. G.

    2007-12-01

    The widely existing shallow decay phase of the X-ray afterglows of gamma-ray bursts (GRBs) is generally accepted to be due to long-lasting energy injection. The outflows carrying the injecting energy, based on the component that is dominant in energy, fall into two possible types: baryon-dominated and lepton-dominated ones. The former type of outflow could be ejecta that is ejected during the prompt phase of a GRB and consists of a series of baryonic shells with a distribution of Lorentz factors, and the latter type could be an electron-positron pair wind that is driven by the postburst central engine. We here provide a unified description for the dynamics of fireballs based on these two types of energy injection and calculate the corresponding high-energy photon emission by considering synchrotron radiation and inverse Compton scattering (including synchrotron self-Compton and combined inverse Compton) of electrons. We find that, in the two energy-injection models, there is a plateau (even a hump) in high-energy light curves during the X-ray shallow decay phase. In particular, a considerable fraction of the injecting energy in the lepton-dominated model can be shared by the long-lasting reverse shock since it is relativistic. Furthermore, almost all of the energy of the reverse shock is carried by leptons, and thus, the inverse Compton emission is enhanced dramatically. Therefore, this model predicts more significant high-energy afterglow emission than the baryon-dominated model. We argue that these observational signatures would be used to discriminate between different energy-injection models in the upcoming Gamma-Ray Large Area Space Telescope (GLAST) era.

  18. High Resolution X-Ray and Light Scattering Studies of Bilayer Smectic A Compounds

    DEFF Research Database (Denmark)

    Litster, J. D.; Als-Nielsen, Jens Aage; Birgeneau, R. J.;

    1979-01-01

    We summarize the results of high resolution X-ray and light scattering studies of the smectic A-nematic transition in cyanobenzylidene-octyloxyaniline, octyloxy-cyanobiphenyl, and octyl-cyanobiphenyl. Pretransitional behavior in the nematic phase is essentially consistent with the He4 analogue pr...... proposed by de Gennes with subtle effects arising from the lack of true long range order in the smectic phase. Elastic constants in the smectic phase show anomalous behavior probably associated with the logarithmically divergent phase fluctuations....

  19. The cooling phase of Type I X-ray bursts observed with RXTE in 4U 1820-30 does not follow the canonical F - T^4 relation

    CERN Document Server

    García, Federico; Méndez, Mariano

    2013-01-01

    We analysed the complete set of bursts from the neutron-star low-mass X-ray binary 4U 1820-30 detected with the Rossi X-ray Timing Explorer (RXTE). We found that all are photospheric radius expansion bursts, and have similar duration, peak flux and fluence. From the analysis of time-resolved spectra during the cooling phase of the bursts, we found that the relation between the bolometric flux and the temperature is very different from the canonical F - T^4 relation that is expected if the apparent emitting area on the surface of the neutron star remains constant. The flux-temperature relation can be fitted using a broken power law, with indices 2.0$\\pm$0.3 and 5.72$\\pm$0.06. The departure from the F - T^4 relation during the cooling phase of the X-ray bursts in 4U 1820-30 could be due to changes in the emitting area of the neutron star while the atmosphere cools-down, variations in the colour-correction factor due to chemical evolution, or the presence of a source of heat, e.g. residual hydrogen nuclear burni...

  20. High-resolution soft X-ray beamline ADRESS at the Swiss Light Source for resonant inelastic X-ray scattering and angle-resolved photoelectron spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    Strocov, V. N., E-mail: vladimir.strocov@psi.ch; Schmitt, T.; Flechsig, U.; Schmidt, T.; Imhof, A.; Chen, Q.; Raabe, J. [Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland); Betemps, R.; Zimoch, D.; Krempasky, J. [Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland); Wang, X. [Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland); Institut de Physique de la Matiére Condensé, Ecole Polytechnique Fédéderale de Lausanne (Switzerland); Grioni, M. [Institut de Physique de la Matiére Condensé, Ecole Polytechnique Fédéderale de Lausanne (Switzerland); Piazzalunga, A. [Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland); Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy); Patthey, L. [Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland)

    2010-09-01

    Concepts and technical realization of the high-resolution soft X-ray beamline ADRESS at the Swiss Light Source are described. Optimization of the optical scheme for high resolution and photon flux as well as diagnostics tools and alignment strategies are discussed. The concepts and technical realisation of the high-resolution soft X-ray beamline ADRESS operating in the energy range from 300 to 1600 eV and intended for resonant inelastic X-ray scattering (RIXS) and angle-resolved photoelectron spectroscopy (ARPES) are described. The photon source is an undulator of novel fixed-gap design where longitudinal movement of permanent magnetic arrays controls not only the light polarization (including circular and 0–180° rotatable linear polarizations) but also the energy without changing the gap. The beamline optics is based on the well established scheme of plane-grating monochromator operating in collimated light. The ultimate resolving power E/ΔE is above 33000 at 1 keV photon energy. The choice of blazed versus lamellar gratings and optimization of their profile parameters is described. Owing to glancing angles on the mirrors as well as optimized groove densities and profiles of the gratings, the beamline is capable of delivering high photon flux up to 1 × 10{sup 13} photons s{sup −1} (0.01% BW){sup −1} at 1 keV. Ellipsoidal refocusing optics used for the RIXS endstation demagnifies the vertical spot size down to 4 µm, which allows slitless operation and thus maximal transmission of the high-resolution RIXS spectrometer delivering E/ΔE > 11000 at 1 keV photon energy. Apart from the beamline optics, an overview of the control system is given, the diagnostics and software tools are described, and strategies used for the optical alignment are discussed. An introduction to the concepts and instrumental realisation of the ARPES and RIXS endstations is given.

  1. Phase shifts and nonellipsoidal light curves: Challenges from mass determinations in x-ray binary stars

    Science.gov (United States)

    Cantrell, Andrew Glenn

    We consider two types of anomalous observations which have arisen from efforts to measure dynamical masses of X-ray binary stars: (1) Radial velocity curves which seemingly show the primary and the secondary out of antiphase in most systems, and (2) The observation of double-waved light curves which deviate significantly from the ellipsoidal modulations expected for a Roche lobe filling star. We consider both problems with the joint goals of understanding the physical origins of the anomalous observations, and using this understanding to allow robust dynamical determinations of mass in X-ray binary systems. In our analysis of phase-shifted radial velocity curves, we discuss a comprehensive sample of X-ray binaries with published phase-shifted radial velocity curves. We show that the most commonly adopted explanation for phase shifts is contradicted by many observations, and consider instead a generalized form of a model proposed by Smak in 1970. We show that this model is well supported by a range of observations, including some systems which had previously been considered anomalous. We lay the groundwork for the derivation of mass ratios based on our explanation for phase shifts, and we discuss the work necessary to produce more detailed physical models of the phase shift. In our analysis of non-ellipsoidal light curves, we focus on the very well-studied system A0620-00. We present new VIH SMARTS photometry spanning 1999-2007, and supplement this with a comprehensive collection of archival data obtained since 1981. We show that A0620-00 undergoes optical state changes within X-ray quiescence and argue that not all quiescent data should be used for determinations of the inclination. We identify twelve light curves which may reliably be used for determining the inclination. We show that the accretion disk contributes significantly to all twelve curves and is the dominant source of nonellipsoidal variations. We derive the disk fraction for each of the twelve curves

  2. Hydrodynamics associated to the X-ray light curve of A0620-00

    CERN Document Server

    Coronado, Y

    2014-01-01

    From 1975 to 1976, an outburst was detected in the light curve of the X-ray transient A0620-00 using the Ariel V and SAS-3 experiments. In this letter we model the outburst with the hydrodynamical model proposed by Mendoza et al. (2009). The physical model is constructed assumming basic mass and momentum conservation laws associated to the motion of the shock waves developed inside the expanding relativistic jet of the source. These internal shock waves are produced as a result of periodic variations of the inyected mass and velocity of the flow at the base of the jet. The observations of this X-ray light curve present two clear bumps. The first one is modelled assuming periodic variations of the inyected velocity at the base of the jet, while the second one can either be modelled by a further velocity oscillations, or by a periodic variation of the mass injection rate at the base of the jet at a latter time. The fitting of the data fixes different parameters of the model, such as the mean mass injection rate...

  3. Hydrodynamics associated to the X-ray light curve of A0620-00

    Science.gov (United States)

    Coronado, Y.; Mendoza, S.

    2015-12-01

    From 1975 to 1976, an outburst was detected in the light curve of the X-ray transient A0620-00 using the Ariel V and SAS-3 experiments. In this article we model the outburst with the hydrodynamical model proposed by Mendoza et al. (Mon. Not. R. Astron. Soc. 395:1403, 2009). The physical model is constructed assuming basic mass and momentum conservation laws associated to the motion of the shock waves developed inside the expanding relativistic jet of the source. These internal shock waves are produced as a result of periodic variations of the injected mass and velocity of the flow at the base of the jet. The observations of this X-ray light curve present two clear bumps. The first one is modelled assuming periodic variations of the injected velocity at the base of the jet, while the second one can either be modelled by further velocity oscillations, or by a periodic variation of the mass injection rate at the base of the jet at a latter time. This latter model is statistically more significant for the observed data, than the former. The fitting of the data fixes different parameters of the model, such as the mean mass injection rate at the base of the jet and the oscillation frequency of the flow as measured on the rest frame of the central source.

  4. Stress manipulated coating for figure reshape of light weight X-ray telescope mirrors

    Science.gov (United States)

    Yao, Youwei; Wang, Xiaoli; Cao, Jian; Graham, Michael E.; Vaynman, Semyon; Grogans, Shannon E.; Cao, Yifang; Ulmer, Melville P.

    2015-09-01

    We present our idea to correct the surface profile of X-ray telescope mirrors by employing a spatially distributed variable stress coating. Future X-ray telescope missions require light weight optics with an angular resolution ≤. 1" . However, the typical desired thickness of a light weight mirror shell is ≤ 0.4mm, and to date such thin shelled mirrors that have been fabricated cannot meet the required figure accuracy. Therefore most the common approach is to modify the figure of the initially produced mirror shell. In this paper, we describe one such approach. Our approach uses a DC magnetron sputtering process with a variable electrical bias. The end result is a locally variable stress which has the potential to improve the figure of the initially fabricated thin . In this work we report out first results. These include: reproducibility, important technical details of the coating process, and the results of stability tests on several samples monitored. Further, as a proof of concept, we applied a coating with a modulated bias to demonstrate the feasibility to manipulate the surface profile.

  5. Examination of the role of the $^{14}$O($\\alpha$,$p$)$^{17}$F reaction rate in type I x-ray bursts

    CERN Document Server

    Hu, J; Parikh, A; Xu, S W; Yamaguchi, H; Kahl, D; Ma, P; Su, J; Wang, H W; Nakao, T; Wakabayashi, Y; Teranishi, T; Hahn, K I; Moon, J Y; Jung, H S; Hashimoto, T; Chen, A A; Irvine, D; Lee, C S; Kubono, S

    2014-01-01

    The $^{14}$O($\\alpha$,$p$)$^{17}$F reaction is one of the key reactions involved in the breakout from the hot-CNO cycle to the rp-process in type I x-ray bursts (XRBs). The resonant properties in the compound nucleus $^{18}$Ne have been investigated through resonant elastic scattering of $^{17}$F+$p$. The radioactive $^{17}$F beam was separated by the CNS Radioactive Ion Beam separator (CRIB) and bombarded a thick H$_2$ gas target at 3.6 MeV/nucleon. The recoiling light particles were measured by three ${\\Delta}$E-E silicon telescopes at laboratory angles of $\\theta$$_{lab}$$\\approx$3$^\\circ$, 10$^\\circ$ and 18$^\\circ$, respectively. Five resonances at $E_{x}$=6.15, 6.28, 6.35, 6.85, and 7.05 MeV were observed in the excitation functions, and their spin-parities have been determined based on an $R$-matrix analysis. In particular, $J^{\\pi}$=1$^-$ was firmly assigned to the 6.15-MeV state which dominates the thermonuclear $^{14}$O($\\alpha$,$p$)$^{17}$F rate below 2 GK. As well, a possible new excited state in $...

  6. Properties of resonant states in 18Ne relevant to key 14O(alpha,p)17F breakout reaction in type I x-ray bursts

    CERN Document Server

    Hu, J; Parikh, A; Xu, S W; Yamaguchi, H; Kahl, D; Ma, P; Su, J; Wang, H W; Nakao, T; Wakabayashi, Y; Teranishi, T; Hahn, K I; Moon, J Y; Sung, H S; Hashimoto, T; Chen, A A; Irvine, D; Lee, C S; Kubono, S

    2014-01-01

    The $^{14}$O($\\alpha$,$p$)$^{17}$F reaction is one of the key reactions involved in the breakout from the hot-CNO cycle to the rp-process in type I x-ray bursts. The resonant properties in the compound nucleus $^{18}$Ne have been investigated through resonant elastic scattering of $^{17}$F+$p$. The radioactive $^{17}$F beam was separated by the CNS Radioactive Ion Beam separator (CRIB) and bombarded a thick H$_2$ gas target at 3.6 MeV/nucleon. The recoiling light particles were measured by using three ${\\Delta}$E-E silicon telescopes at laboratory angles of $\\theta$$_{lab}$$\\approx$3$^\\circ$, 10$^\\circ$ and 18$^\\circ$, respectively. Five resonances at $E_{x}$=6.15, 6.28, 6.35, 6.85, and 7.05 MeV were observed in the excitation functions. Based on an $R$-matrix analysis, $J^{\\pi}$=1$^-$ was firmly assigned to the 6.15-MeV state. This state dominates the thermonuclear $^{14}$O($\\alpha$,$p$)$^{17}$F rate below 1 GK. We have also confirmed the existence and spin-parities of three states between 6.1 and 6.4 MeV. A...

  7. Models of Type I X-ray Bursts from GS 1826-24: A Probe of rp-Process Hydrogen Burning

    CERN Document Server

    Heger, Alexander; Galloway, Duncan K; Woosley, Stanford E

    2007-01-01

    The X-ray burster GS 1826-24 shows extremely regular Type I X-ray bursts whose energetics and recurrence times agree well with thermonuclear ignition models. We present calculations of sequences of burst lightcurves using multizone models which follow the rp-process nucleosynthesis with an extensive nuclear reaction network. The theoretical and observed burst lightcurves show remarkable agreement. The models naturally explain the slow ~5s rise and long ~100s tails of these bursts, as well as their dependence on mass accretion rate. This comparison provides further evidence for solar metallicity in the accreted material in this source, and constrains the distance to the source. The main difference is that the observed lightcurves do not show the distinct two-stage rise of the models. This may reflect the time for burning to spread over the stellar surface, or may indicate that our treatment of heat transport or nuclear physics needs to be revised. The trends in burst properties with accretion rate are well-rep...

  8. Nanoscale thermal, acoustic, and magnetic dynamics probed with soft x-ray light

    Science.gov (United States)

    Siemens, Mark E.

    This thesis discusses the application of coherent, ultrafast beams of soft x-ray light from high-order harmonic generation (HHG) to study thermal, acoustic, and magnetic processes in nanostructures. This short-wavelength light is a uniquely powerful probe of surface dynamics since it has both a very short wavelength and duration. First, this thesis reports the first observation and quantitative measurements of the transition from diffusive to ballistic thermal transport for the case of heat flow away from a heated nanostructure into a bulk substrate. This measurement provides insight into the fundamentals of thermal energy transport away from nanoscale hot spots, and demonstrates a fundamental limit to the energy dissipation capability of nanostructures. Further, we propose a straightforward correction to the Fourier law for heat diffusion, necessary for thermal management in nanoelectronics, nano-enabled energy systems, nanomanufacturing, and nanomedicine. Second, this work discusses dynamic measurements of ultra-high frequency surface acoustic waves (SAW) and the first SAW dispersion measurement in a nanostructured system. These results are directly applicable to adhesion and thickness diagnostics of very thin films. Finally, this thesis reports the first use of light from HHG to study magnetic orientation. Using the transverse magneto-optic Kerr effect and soft x-ray light near the M-absorption edges of Fe, Co, and Ni, magnetic asymmetries up to 8% are observed from thin Permalloy (Ni80Fe20) films. This signal is 1-2 orders of magnitude higher than that observed using optical methods, showing great promise for dynamic imaging of domain flipping at the 100 nm level.

  9. Development of Resonant Soft X-ray Scattering for Polymer Systems at Advanced Light Source

    Science.gov (United States)

    Wang, Cheng; Hexemer, Alexander; Nasiatka, James; Chan, Elaine; Padmore, Howard

    2010-03-01

    It is envisioned that many polymer applications will rely on the heterogeneous morphologies of polymer blends or block copolymers to yield specific functional properties, such as organic light-emitting diodes and photovoltaics. Over the past few years, it has been strongly demonstrated that scattering at soft x-ray energies near the carbon K-edge yields chemically specific and enhanced contrast, thereby enabling structural studies of heterogeneous polymer films with thicknesses of only tens of nanometers. Resonant soft x-ray scattering (RSoXS) will provide the capability for a high-resolution chemical probe with interfacial sensitivity. We will discuss here the development of a dedicated RSoXS setup at the ALS Beamline 11.0.1, which is an elliptically polarized undulator beamline that covers the energy range of 200-1300 eV. It can accommodate a large variety of thin film samples and scattering geometries, including transmission, specular and off-specular reflection, as well as grazing incidence geometries, that will enable users to study both laterally- and depth-resolved structures. The generality, strength, and ease of RSoXS will have significant and immediate impacts in many areas of polymer science and technology. This will be achieved through systematic, collaborative studies of materials with potentially high impact applications.

  10. Synchrotron X-Ray Microdiffraction Studies of Electromigration in Interconnect lines at the Advanced Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Tamura, Nobumichi; Chen, Kai; Kunz, Martin

    2009-05-01

    Synchrotron polychromatic X-ray microdiffraction is a particularly suitable technique to study in situ the effect of electromigration in metal interconnects as add spatial resolution to grain orientation and strain sensitivity. This technique has been extensively used at the Advanced Light Source to monitor changes in aluminum and copper interconnect test structures while high-density current is passed into them during accelerated tests at elevated temperature. One of the principal findings is the observation of electromigration-induced plasticity in the metal lines that appear during the very early stages of electromigration. In some of the lines, high density of geometrically necessary dislocation are formed leading to additional diffusion paths causing an enhancement of electromigration effect at test temperature. This paper presents an overview of the principal results obtained from X-ray microdiffraction studies of electromigration effects on aluminum and copper interconnects at the ALS throughout continuous efforts that spanned over a decade (1998-2008) from approximately 40 weeks of combined beamtime.

  11. Evaluating scintillator performance in time-resolved hard X-ray studies at synchrotron light sources.

    Science.gov (United States)

    Rutherford, Michael E; Chapman, David J; White, Thomas G; Drakopoulos, Michael; Rack, Alexander; Eakins, Daniel E

    2016-05-01

    The short pulse duration, small effective source size and high flux of synchrotron radiation is ideally suited for probing a wide range of transient deformation processes in materials under extreme conditions. In this paper, the challenges of high-resolution time-resolved indirect X-ray detection are reviewed in the context of dynamic synchrotron experiments. In particular, the discussion is targeted at two-dimensional integrating detector methods, such as those focused on dynamic radiography and diffraction experiments. The response of a scintillator to periodic synchrotron X-ray excitation is modelled and validated against experimental data collected at the Diamond Light Source (DLS) and European Synchrotron Radiation Facility (ESRF). An upper bound on the dynamic range accessible in a time-resolved experiment for a given bunch separation is calculated for a range of scintillators. New bunch structures are suggested for DLS and ESRF using the highest-performing commercially available crystal LYSO:Ce, allowing time-resolved experiments with an interframe time of 189 ns and a maximum dynamic range of 98 (6.6 bits).

  12. Demonstration of a time-resolved x-ray scattering instrument utilizing the full-repetition rate of x-ray pulses at the Pohang Light Source

    Science.gov (United States)

    Jo, Wonhyuk; Eom, Intae; Landahl, Eric C.; Lee, Sooheyong; Yu, Chung-Jong

    2016-03-01

    We report on the development of a new experimental instrument for time-resolved x-ray scattering (TRXS) at the Pohang Light Source (PLS-II). It operates with a photon energy ranging from 5 to 18 keV. It is equipped with an amplified Ti:sappahire femtosecond laser, optical diagnostics, and laser beam delivery for pump-probe experiments. A high-speed single-element detector and high trigger-rate oscilloscope are used for rapid data acquisition. While this instrument is capable of measuring sub-nanosecond dynamics using standard laser pump/x-ray probe techniques, it also takes advantage of the dense 500 MHz standard fill pattern in the PLS-II storage ring to efficiently record nano-to-micro-second dynamics simultaneously. We demonstrate this capability by measuring both the (fast) impulsive strain and (slower) thermal recovery dynamics of a crystalline InSb sample following intense ultrafast laser excitation. Exploiting the full repetition rate of the storage ring results in a significant improvement in data collection rates compared to conventional bunch-tagging methods.

  13. Analytical computation of stray light in nested mirror modules for x-ray telescopes

    Science.gov (United States)

    Spiga, Daniele

    2015-09-01

    Stray light in X-ray telescopes are a well-known issue. Unlike rays focused via a double reflection by usual grazing-incidence geometries such as the Wolter-I, stray rays coming from off-axis sources are reflected only once by either the parabolic or the hyperbolic segment. Although not focused, stray light may represent a major source of background and ghost images especially when observing a field of faint sources in the vicinities of another, more intense, just outside the field of view of the telescope. The stray light problem is faced by mounting a pre-collimator in front of the mirror module, in order to shade a part of the reflective surfaces that may give rise to singly-reflected rays. Studying the expected stray light impact, and consequently designing a pre-collimator, is a typical ray-tracing problem, usually time and computation consuming, especially if we consider that rays propagate throughout a densely nested structure. This in turn requires one to pay attention to all the possible obstructions, increasing the complexity of the simulation. In contrast, approaching the problems of stray light calculation from an analytical viewpoint largely simplifies the problem, and may also ease the task of designing an effective pre-collimator. In this work we expose an analytical formalism that can be used to compute the stray light in a nested optical module in a fast and effective way, accounting for obstruction effects.

  14. Synchrotron X-Ray Microdiffraction Studies of Electromigration in Interconnect lines at the Advanced Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Tamura, Nobumichi; Chen, Kai; Kunz, Martin

    2009-12-01

    Synchrotron polychromatic X-ray microdiffraction is a particularly suitable technique to study in situ the effect of electromigration in metal interconnects as add spatial resolution to grain orientation and strain sensitivity. This technique has been extensively used at the Advanced Light Source to monitor changes in aluminum and copper interconnect test structures while high-density current is passed into them during accelerated tests at elevated temperature. One of the principal findings is the observation of electromigration-induced plasticity in the metal lines that appear during the very early stages of electromigration. In some of the lines, high density of geometrically necessary dislocation are formed leading to additional diffusion paths causing an enhancement of electromigration effect at test temperature.

  15. Fast X-ray imaging at beamline I13L at Diamond Light Source

    Science.gov (United States)

    De Fanis, A.; Pešić, Z. D.; Wagner, U.; Rau, C.

    2013-03-01

    The imaging branch of the dual-branch beamline I13L at Diamond Light Source has been operational since April 2012. This branch is dedicated to hard X-ray imaging (in-line phase contrast radiography and tomography, and full-field microscopy), with energies in the ranges 6-30keV. At present we aim to achieve spatial resolution of the order of 1 μm over a field of view of l-20mm2. This branch aims to excel at imaging experiment of fast dynamic processes, where it is of interest to have short exposure times and high frame rates. To accommodate for this, we prepared for the beamline to operate with "pink" beam to provide higher flux, an efficient detection system, and rapid data acquisition, transfer, and saving to storage. This contributed paper describes the present situation and illustrate the author's goal for the mid-future.

  16. X-RAY IRRADIATION OF H{sub 2}O + CO ICE MIXTURES WITH SYNCHROTRON LIGHT

    Energy Technology Data Exchange (ETDEWEB)

    Jiménez-Escobar, A.; Ciaravella, A.; Micela, G.; Cecchi-Pestellini, C. [INAF–Osservatorio Astronomico di Palermo, P.za Parlamento 1, I-90134 Palermo (Italy); Chen, Y.-J.; Huang, C.-H., E-mail: jimenezea@astropa.inaf.it, E-mail: ciarave@astropa.inaf.it, E-mail: giusi@astropa.inaf.it, E-mail: cecchi-pestellini@astropa.inaf.it, E-mail: asperchen@phy.ncu.edu.tw, E-mail: 101222023@cc.ncu.edu.tw [Department of Physics, National Central University, Jhongli District, Taoyuan City 32054, Taiwan (China)

    2016-03-20

    We irradiated a (4:1) mixture of water and carbon monoxide with soft X-rays of energies up to 1.2 keV. The experiments were performed using the spherical grating monochromator beamline at National Synchrotron Radiation Research Center in Taiwan. Both monochromatic (300 and 900 eV) and broader energy fluxes (250–1200 eV) were employed. During the irradiation, the H{sub 2}O + CO mixture was ionized, excited, and fragmented, producing a number of reactive species. The composition of the ice has been monitored throughout both the irradiation and warm-up phases. We identified several products, which can be related through a plausible chemical reaction scheme. Such chemistry is initiated by the injection of energetic photoelectrons that produce multiple ionization events generating a secondary electron cascade. The results have been discussed in light of a model for protoplanetary disks around young solar-type stars.

  17. Synchrotron Vacuum Ultraviolet Light and Soft X-Ray Radiation Effects on Aluminized Teflon FEP Investigated

    Science.gov (United States)

    Dever, Joyce A.; Townsend, Jacqueline A.; Gaier, James R.; Jalics, Alice I.

    1999-01-01

    Since the Hubble Space Telescope (HST) was deployed in low Earth orbit in April 1990, two servicing missions have been conducted to upgrade its scientific capabilities. Minor cracking of second-surface metalized Teflon FEP (DuPont; fluorinated ethylene propylene) surfaces from multilayer insulation (MLI) was first observed upon close examination of samples with high solar exposure retrieved during the first servicing mission, which was conducted 3.6 years after deployment. During the second HST servicing mission, 6.8 years after deployment, astronaut observations and photographic documentation revealed significant cracks in the Teflon FEP layer of the MLI on both the solar- and anti-solar-facing surfaces of the telescope. NASA Goddard Space Flight Center directed the efforts of the Hubble Space Telescope MLI Failure Review Board, whose goals included identifying the low-Earth-orbit environmental constituent(s) responsible for the cracking and embrittling of Teflon FEP which was observed during the second servicing mission. The NASA Lewis Research Center provided significant support to this effort. Because soft x-ray radiation from solar flares had been considered as a possible cause for the degradation of the mechanical properties of Teflon FEP (ref. 1), the effects of soft xray radiation and vacuum ultraviolet light on Teflon FEP were investigated. In this Lewisled effort, samples of Teflon FEP with a 100-nm layer of vapor-deposited aluminum (VDA) on the backside were exposed to synchrotron radiation of various vacuum ultraviolet and soft x-ray wavelengths between 18 nm (69 eV) and 0.65 nm (1900 eV). Synchrotron radiation exposures were conducted using the National Synchrotron Light Source at Brookhaven National Laboratory. Samples of FEP/VDA were exposed with the FEP surface facing the synchrotron beam. Doses and fluences were compared with those estimated for the 20-yr Hubble Space Telescope mission.

  18. Next Generation Astronomical X-ray Optics: High Angular Resolution, Light Weight, and Low Production Cost

    Science.gov (United States)

    Zhang. W. W.; Biskach, M. P.; Blake, P. N.; Chan, K. W.; Gaskin, J. A.; Hong, M. L.; Jones, W. D.; Kolos, L. D.; Mazzarella, J. R.; McClelland, R. S.; O'Dell, S. L.; Saha, T. T.; Sharpe, M. V.

    2012-01-01

    X-ray astronomy depends on the availability of telescopes with high resolution and large photon collecting areas. Since x-ray observation can only be carried out above the atmosphere, these telescopes must be necessarily lightweight. Compounding the lightweight requirement is that an x-ray telescope consists of many nested concentric shells, which further require that x-ray mirrors must also be geometrically thin to achieve high packing efficiency. This double lightweight and geometrically thin requirement poses significant technical challenges in fabricating the mirrors and in integrating them into mirror assemblies. This paper reports on the approach, strategy and status of our x-ray optics development program whose objective is to meet these technical challenges at modest cost to enable future x-ray missions, including small Explorer missions in the near term, probe class missions in the medium term, and large flagship missions in the long term.

  19. BURST FLUENCE DISTRIBUTIONS OF SOFT GAMMA REPEATERS 1806-20 AND 1900+14 IN THE ROSSI X-RAY TIMING EXPLORER PCA ERA

    Energy Technology Data Exchange (ETDEWEB)

    Prieskorn, Zachary; Kaaret, Philip, E-mail: prieskorn@psu.edu [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States)

    2012-08-10

    We study the fluence distributions of over 3040 bursts from SGR 1806-20 and over 1963 bursts from SGR 1900+14 using the complete set of observations available from the Rossi X-Ray Timing Explorer/Proportional Counter Array through 2011 March. Cumulative event distributions are presented for both sources and are fitted with single and broken power laws as well as an exponential cutoff. The distributions are best fitted by a broken power law with exponential cutoff; however the statistical significance of the cutoff is not high and the upper portion of the broken power law can be explained as the expected number of false bursts due to random noise fluctuations. Event distributions are also examined in high and low burst rate regimes and power-law indices are found to be consistent, independent of the burst rate. The contribution function of the event fluence is calculated. This distribution shows that the energy released in the soft gamma repeater (SGR) bursts is dominated by the most powerful events for both sources. The power-law nature of these distributions combined with the dominant energy dissipation of the system occurring in the large, less frequent bursts is indicative of a self-organized critical system, as suggested by Gogus et al. in 1999.

  20. Next Generation X-ray Optics: High Angular Resolution, Light Weight, and Low Production Cost

    Science.gov (United States)

    Zhang, William

    2014-08-01

    Every conceivable future x-ray astronomical mission would require x-ray optics. These optics must meet the three-fold requirements of angular resolution, effective area, and cost.In this poster we will present the rationale, technical approach, and status of an x-ray optics technology development program that has been underway at Goddard Space Flight Center and Marshall Space Flight Center.

  1. Analytical computation of stray light in nested mirror modules for X-ray telescopes

    CERN Document Server

    Spiga, Daniele

    2016-01-01

    Stray light in X-ray telescopes is a well-known issue. Unlike rays focused via a double reflection by usual grazing-incidence geometries such as the Wolter-I, stray rays coming from off-axis sources are reflected only once by either the parabolic or the hyperbolic segment. Although not focused, stray light may represent a major source of background and ghost images especially when observing a field of faint sources in the vicinities of another, more intense, just outside the field of view of the telescope. The stray light problem is faced by mounting a pre-collimator in front of the mirror module, in order to shade a part of the reflective surfaces that may give rise to singly-reflected rays. Studying the expected stray light impact, and consequently designing a pre-collimator, is a typical ray-tracing problem, usually time and computation consuming, especially if we consider that rays propagate throughout a densely nested structure. This in turn requires one to pay attention to all the possible obstructions,...

  2. Development of a microsecond X-ray protein footprinting facility at the Advanced Light Source

    Science.gov (United States)

    Gupta, Sayan; Celestre, Richard; Petzold, Christopher J.; Chance, Mark R.; Ralston, Corie

    2014-01-01

    X-ray footprinting (XF) is an important structural biology tool used to determine macromolecular conformations and dynamics of both nucleic acids and proteins in solution on a wide range of timescales. With the impending shut-down of the National Synchrotron Light Source, it is ever more important that this tool continues to be developed at other synchrotron facilities to accommodate XF users. Toward this end, a collaborative XF program has been initiated at the Advanced Light Source using the white-light bending-magnet beamlines 5.3.1 and 3.2.1. Accessibility of the microsecond time regime for protein footprinting is demonstrated at beamline 5.3.1 using the high flux density provided by a focusing mirror in combination with a micro-capillary flow cell. It is further reported that, by saturating samples with nitrous oxide, the radiolytic labeling efficiency is increased and the imprints of bound versus bulk water can be distinguished. These results both demonstrate the suitability of the Advanced Light Source as a second home for the XF experiment, and pave the way for obtaining high-quality structural data on complex protein samples and dynamics information on the microsecond timescale. PMID:24971962

  3. An Explanation for the Different X-ray to Optical Column Densities in the Environments of Gamma Ray Bursts: A Progenitor Embedded in a Dense Medium

    CERN Document Server

    Krongold, Yair

    2013-01-01

    We study the > 10 ratios in the X-ray to optical column densities inferred from afterglow spectra of Gamma Ray Bursts due to gas surrounding their progenitors. We present time-evolving photoionization calculations for these afterglows and explore different conditions for their environment. We find that homogenous models of the environment (constant density) predict X-ray columns similar to those found in the optical spectra, with the bulk of the opacity being produced by neutral material at large distances from the burst. This result is independent of gas density or metallicity. Only models assuming a progenitor immersed in a dense (10^(2-4) cm-3) cloud of gas (with radius ~10 pc), with a strong, declining gradient of density for the surrounding interstellar medium are able to account for the large X-ray to optical column density ratios. However, to avoid an unphysical correlation between the size of this cloud, and the size of the ionization front produced by the GRB, the models also require that the circumb...

  4. New Directions in X-Ray Light Sources or Fiat Lux: what's under the dome and watching atoms with x-rays (LBNL Summer Lecture Series)

    Energy Technology Data Exchange (ETDEWEB)

    Falcone, Roger

    2008-07-15

    Summer Lecture Series 2008: Molecular movies of chemical reactions and material phase transformations need a strobe of x-rays, the penetrating light that reveals how atoms and molecules assemble in chemical and biological systems and complex materials. Roger Falcone, Director of the Advanced Light Source,will discuss a new generation of x ray sources that will enable a new science of atomic dynamics on ultrafast timescales.

  5. DEVELOPMENTS IN SYNCHROTRON X-RAY COMPUTED MICROTOMOGRAPHY AT THE NATIONAL SYNCHROTRON LIGHT SOURCE.

    Energy Technology Data Exchange (ETDEWEB)

    DOWD,B.A.

    1999-07-23

    Last year, the X27A beamline at the National Synchrotron Light Source (NSLS) became dedicated solely to X-Ray Computed Microtomography (XCMT). This is a third-generation instrument capable of producing tomographic volumes of 1-2 micron resolution over a 2-3mm field of view. Recent enhancements will be discussed. These have focused on two issues: the desire for real-time data acquisition and processing and the need for highly monochromatic beam (.1 % energy bandpass). The latter will permit k-edge subtraction studies and will provide improved image contrast from below the Cr (6 keV) up to the Cs (36 keV) k-edge. A range of applications that benefit from these improvements will be discussed as well. These two goals are somewhat counterproductive, however; higher monochromaticity yields a lower flux forcing longer data acquisition times. To balance the two, a more efficient scintillator for X-ray conversion is being developed. Some testing of a prototype scintillator has been performed; preliminary results will be presented here. In the meantime, data reconstruction times have been reduced, and the entire tomographic acquisition, reconstruction and volume rendering process streamlined to make efficient use of synchrotron beam time. A Fast Filtered Back Transform (FFBT) reconstruction program recently developed helped to reduce the time to reconstruct a volume of 150 x 150 x 250 pixels{sup 3} (over 5 million voxels) from the raw camera data to 1.5 minutes on a dual R10,000 CPU. With these improvements, one can now obtain a ''quick look'' of a small tomographic volume ({approximately}10{sup 6}voxels) in just over 15 minutes from the start of data acquisition.

  6. LIGHT SOURCE: Spot size diagnostics for flash radiographic X-ray sources at LAPA

    Science.gov (United States)

    Li, Cheng-Gang; Li, Qin; Shi, Jin-Shui; Deng, Jian-Jun

    2009-06-01

    Spot size is one of the parameters to characterize the performance of a radiographic X-ray source. It determines the degree of blurring due to magnification directly. In recent years, a variety of measurement methods have been used to diagnose X-ray spot size at Laboratory of Accelerator Physics and Application (LAPA). Computer simulations and experiments showed that using a rolled-edge to measure the spot size are more accurate, and the intensity distribution of X-ray source was obtained by a device with a square aperture. Experimental and simulation results on a flash X-ray source at our laboratory are presented and discussed in this paper. In addition, a new method for time resolved diagnostics of X-ray spot size is introduced too.

  7. X-ray spectroscopy of light kaonic atoms – new results and perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Marton, J. [Stefan-Meyer-Institut für subatomare Physik, Boltzmanngasse 3, 1090 Wien (Austria); Bazzi, M. [INFN, Laboratori Nazionali di Frascati, C.P. 13, Via E. Fermi 40, I-00044 Frascati (Roma) (Italy); Beer, G. [Dep. of Physics and Astronomy, University of Victoria, P.O.Box 3055, Victoria B.C. Canada V8W3P6 (Canada); Berucci, C. [INFN, Laboratori Nazionali di Frascati, C.P. 13, Via E. Fermi 40, I-00044 Frascati (Roma) (Italy); Bombelli, L. [Politecnico di Milano, Dip. di Elettronica e Informazione, Piazza L. da Vinci, 32 I-20133 Milano (Italy); Bragadireanu, A.M. [INFN, Laboratori Nazionali di Frascati, C.P. 13, Via E. Fermi 40, I-00044 Frascati (Roma) (Italy); IFIN-HH, P.O. box MG-6, R76900 Magurele, Bucharest (Romania); Cargnelli, M. [Stefan-Meyer-Institut für subatomare Physik, Boltzmanngasse 3, 1090 Wien (Austria); Curceanu, C. [INFN, Laboratori Nazionali di Frascati, C.P. 13, Via E. Fermi 40, I-00044 Frascati (Roma) (Italy); D' Uffizi, A.; Fiorini, C.; Frizzi, T. [Politecnico di Milano, Dip. di Elettronica e Informazione, Piazza L. da Vinci, 32 I-20133 Milano (Italy); Ghio, F. [INFN Sez. di Roma I and Instituto Superiore di Sanita I-00161, Roma (Italy); Guaraldo, C. [INFN, Laboratori Nazionali di Frascati, C.P. 13, Via E. Fermi 40, I-00044 Frascati (Roma) (Italy); Hayano, R. [University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo (Japan); Iliescu, M. [INFN, Laboratori Nazionali di Frascati, C.P. 13, Via E. Fermi 40, I-00044 Frascati (Roma) (Italy); Ishiwatari, T. [Stefan-Meyer-Institut für subatomare Physik, Boltzmanngasse 3, 1090 Wien (Austria); Iwasaki, M. [RIKEN, Institute of Physical and Chemical Research, Saitama (Japan); and others

    2012-12-15

    The antikaon interaction on nucleons and nuclei in the low-energy regime is neither simple nor well understood. Rather direct access to this field is provided by x-ray spectroscopy of light kaonic atoms like kaonic hydrogen, deuterium and helium isotopes. A series of precision measurements on kaonic atoms was performed very successfully by the SIDDHARTA Collaboration at the DAΦNE electron-positron collider at LNF-INFN (Frascati, Italy). Consequently, new precision data on the strong interaction observables (i.e. energy shift and broadening of low-lying atomic states) were delivered having an important impact on the theory of low-energy QCD with strangeness. Presently, the follow-up experiment, SIDDHARTA-2, is in preparation, aiming at a determination of the strong interaction observables in kaonic deuterium as the highest priority; other type of measurements (light and heavier kaonic atoms) are as well foreseen. With the kaonic deuterium data the antikaon-nucleon isospin-resolved scattering lengths can be extracted for the first time. An overview of the progress and present status of experimental studies and an outlook to future perspectives in this fascinating research field is given.

  8. AN EXPLANATION FOR THE DIFFERENT X-RAY TO OPTICAL COLUMN DENSITIES IN THE ENVIRONMENTS OF GAMMA RAY BURSTS: A PROGENITOR EMBEDDED IN A DENSE MEDIUM

    Energy Technology Data Exchange (ETDEWEB)

    Krongold, Yair [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-264, 04510 Mexico DF (Mexico); Prochaska, J. Xavier, E-mail: xavier@ucolick.org [Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)

    2013-09-10

    We study the {approx}> 10 ratios in the X-ray to optical column densities inferred from afterglow spectra of gamma ray bursts (GRBs) due to gas surrounding their progenitors. We present time-evolving photoionization calculations for these afterglows and explore different conditions of their environment. We find that homogenous models of the environment (constant density) predict X-ray columns similar to those found in the optical spectra, with the bulk of the opacity being produced by neutral material at large distances from the burst. This result is independent of gas density or metallicity. Only models assuming a progenitor immersed in a dense ({approx}10{sup 2-4} cm{sup -3}) cloud of gas (with radius {approx}10 pc), with a strong, declining gradient of density for the surrounding interstellar medium (ISM) are able to account for the large X-ray to optical column density ratios. However, to avoid an unphysical correlation between the size of this cloud and the size of the ionization front produced by the GRB, the models also require that the circumburst medium is already ionized prior to the burst. The inferred cloud masses are {approx}< 10{sup 6} M{sub Sun }, even if low metallicities in the medium are assumed (Z {approx} 0.1 Z{sub Sun }). These cloud properties are consistent with those found in giant molecular clouds and our results support a scenario in which the progenitors reside within intense star formation regions of galaxies. Finally, we show that modeling over large samples of GRB afterglows may offer strong constraints on the range of properties in these clouds, and the host galaxy ISM.

  9. LIGHT SOURCE: A simulation study of Tsinghua Thomson scattering X-ray source

    Science.gov (United States)

    Tang, Chuan-Xiang; Li, Ren-Kai; Huang, Wen-Hui; Chen, Huai-Bi; Du, Ying-Chao; Du, Qiang; Du, Tai-Bin; He, Xiao-Zhong; Hua, Jian-Fei; Lin, Yu-Zhen; Qian, Hou-Jun; Shi, Jia-Ru; Xiang, Dao; Yan, Li-Xin; Yu, Pei-Cheng

    2009-06-01

    Thomson scattering X-ray sources are compact and affordable facilities that produce short duration, high brightness X-ray pulses enabling new experimental capacities in ultra-fast science studies, and also medical and industrial applications. Such a facility has been built at the Accelerator Laboratory of Tsinghua University, and upgrade is in progress. In this paper, we present a proposed layout of the upgrade with design parameters by simulation, aiming at high X-ray pulses flux and brightness, and also enabling advanced dynamics studies and applications of the electron beam. Design and construction status of main subsystems are also presented.

  10. All-diamond optical assemblies for a beam-multiplexing X-ray monochromator at the Linac Coherent Light Source

    CERN Document Server

    Stoupin, S; Blank, V D; Shvyd'ko, Yu V; Goetze, K; Assoufid, L; Polyakov, S N; Kuznetsov, M S; Kornilov, N V; Katsoudas, J; Alonso-Mori, R; Chollet, M; Feng, Y; Glownia, J M; Lemke, H; Robert, A; Song, S; Sikorski, M; Zhu, D

    2014-01-01

    A double-crystal diamond (111) monochromator recently implemented at the Linac Coherent Light Source (LCLS) enables splitting of the primary X-ray beam into a pink (transmitted) and a monochromatic (reflected) branch. The first monochromator crystal with a thickness of 100 um provides sufficient X-ray transmittance to enable simultaneous operation of two beamlines. Here we report on the design, fabrication, and X-ray characterization of the first and second (300-um-thick) crystals utilized in the monochromator and the optical assemblies holding these crystals. Each crystal plate has a region of about 5 X 2 mm2 with low defect concentration, sufficient for use in X-ray optics at the LCLS. The optical assemblies holding the crystals were designed to provide mounting on a rigid substrate and to minimize mounting-induced crystal strain. The induced strain was evaluated using double-crystal X-ray topography and was found to be small over the 5 X 2 mm2 working regions of the crystals.

  11. Coherent diffraction of single Rice Dwarf virus particles using hard X-rays at the Linac Coherent Light Source

    Science.gov (United States)

    Munke, Anna; Andreasson, Jakob; Aquila, Andrew; Awel, Salah; Ayyer, Kartik; Barty, Anton; Bean, Richard J.; Berntsen, Peter; Bielecki, Johan; Boutet, Sébastien; Bucher, Maximilian; Chapman, Henry N.; Daurer, Benedikt J.; DeMirci, Hasan; Elser, Veit; Fromme, Petra; Hajdu, Janos; Hantke, Max F.; Higashiura, Akifumi; Hogue, Brenda G.; Hosseinizadeh, Ahmad; Kim, Yoonhee; Kirian, Richard A.; Reddy, Hemanth K.N.; Lan, Ti-Yen; Larsson, Daniel S.D.; Liu, Haiguang; Loh, N. Duane; Maia, Filipe R.N.C.; Mancuso, Adrian P.; Mühlig, Kerstin; Nakagawa, Atsushi; Nam, Daewoong; Nelson, Garrett; Nettelblad, Carl; Okamoto, Kenta; Ourmazd, Abbas; Rose, Max; van der Schot, Gijs; Schwander, Peter; Seibert, M. Marvin; Sellberg, Jonas A.; Sierra, Raymond G.; Song, Changyong; Svenda, Martin; Timneanu, Nicusor; Vartanyants, Ivan A.; Westphal, Daniel; Wiedorn, Max O.; Williams, Garth J.; Xavier, Paulraj Lourdu; Yoon, Chun Hong; Zook, James

    2016-01-01

    Single particle diffractive imaging data from Rice Dwarf Virus (RDV) were recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS). RDV was chosen as it is a well-characterized model system, useful for proof-of-principle experiments, system optimization and algorithm development. RDV, an icosahedral virus of about 70 nm in diameter, was aerosolized and injected into the approximately 0.1 μm diameter focused hard X-ray beam at the CXI instrument of LCLS. Diffraction patterns from RDV with signal to 5.9 Ångström were recorded. The diffraction data are available through the Coherent X-ray Imaging Data Bank (CXIDB) as a resource for algorithm development, the contents of which are described here. PMID:27478984

  12. Coherent diffraction of single Rice Dwarf virus particles using hard X-rays at the Linac Coherent Light Source.

    Science.gov (United States)

    Munke, Anna; Andreasson, Jakob; Aquila, Andrew; Awel, Salah; Ayyer, Kartik; Barty, Anton; Bean, Richard J; Berntsen, Peter; Bielecki, Johan; Boutet, Sébastien; Bucher, Maximilian; Chapman, Henry N; Daurer, Benedikt J; DeMirci, Hasan; Elser, Veit; Fromme, Petra; Hajdu, Janos; Hantke, Max F; Higashiura, Akifumi; Hogue, Brenda G; Hosseinizadeh, Ahmad; Kim, Yoonhee; Kirian, Richard A; Reddy, Hemanth K N; Lan, Ti-Yen; Larsson, Daniel S D; Liu, Haiguang; Loh, N Duane; Maia, Filipe R N C; Mancuso, Adrian P; Mühlig, Kerstin; Nakagawa, Atsushi; Nam, Daewoong; Nelson, Garrett; Nettelblad, Carl; Okamoto, Kenta; Ourmazd, Abbas; Rose, Max; van der Schot, Gijs; Schwander, Peter; Seibert, M Marvin; Sellberg, Jonas A; Sierra, Raymond G; Song, Changyong; Svenda, Martin; Timneanu, Nicusor; Vartanyants, Ivan A; Westphal, Daniel; Wiedorn, Max O; Williams, Garth J; Xavier, Paulraj Lourdu; Yoon, Chun Hong; Zook, James

    2016-08-01

    Single particle diffractive imaging data from Rice Dwarf Virus (RDV) were recorded using the Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS). RDV was chosen as it is a well-characterized model system, useful for proof-of-principle experiments, system optimization and algorithm development. RDV, an icosahedral virus of about 70 nm in diameter, was aerosolized and injected into the approximately 0.1 μm diameter focused hard X-ray beam at the CXI instrument of LCLS. Diffraction patterns from RDV with signal to 5.9 Ångström were recorded. The diffraction data are available through the Coherent X-ray Imaging Data Bank (CXIDB) as a resource for algorithm development, the contents of which are described here.

  13. National Synchrotron Light Source user`s manual: Guide to the VUV and x-ray beamlines. Fifth edition

    Energy Technology Data Exchange (ETDEWEB)

    Gmuer, N.F. [ed.

    1993-04-01

    The success of the National Synchrotron Light Source is based, in large part, on the size of the user community and the diversity of the scientific and technical disciplines represented by these users. As evidence of this success, the VUV Ring has just celebrated its 10th anniversary and the X-ray Ring will do the same in 1995. In order to enhance this success, the NSLS User`s Manual: Guide to the VUV and X-Ray Beamlines - Fifth Edition, is being published. This Manual presents to the scientific community-at-large the current and projected architecture, capabilities and research programs of the various VUV and X-ray beamlines. Also detailed is the research and computer equipment a General User can expect to find and use at each beamline when working at the NSLS. The Manual is updated periodically in order to keep pace with the constant changes on these beamlines.

  14. Combining THz laser excitation with resonant soft X-ray scattering at the Linac Coherent Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Turner, Joshua J., E-mail: joshuat@slac.stanford.edu; Dakovski, Georgi L.; Hoffmann, Matthias C. [Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Hwang, Harold Y. [Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Zarem, Alex; Schlotter, William F.; Moeller, Stefan; Minitti, Michael P. [Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Staub, Urs [Swiss Light Source, Paul Scherrer Institut, 5232 Villigen (Switzerland); Johnson, Steven [ETH Zurich, Institute for Quantum Electronics, Wolfgang-Pauli-Strasse 16, 8093 Zurich (Switzerland); Mitra, Ankush; Swiggers, Michele; Noonan, Peter; Curiel, G. Ivan; Holmes, Michael [Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)

    2015-04-11

    This paper describes new instrumentation developments at the LCLS for materials studies using THz laser excitation and resonant soft X-ray scattering. This paper describes the development of new instrumentation at the Linac Coherent Light Source for conducting THz excitation experiments in an ultra high vacuum environment probed by soft X-ray diffraction. This consists of a cantilevered, fully motorized mirror system which can provide 600 kV cm{sup −1} electric field strengths across the sample and an X-ray detector that can span the full Ewald sphere with in-vacuum motion. The scientific applications motivated by this development, the details of the instrument, and spectra demonstrating the field strengths achieved using this newly developed system are discussed.

  15. Studying nanomagnets and magnetic heterostructures with X-ray PEEM at the Swiss Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Le Guyader, Loiec; Kleibert, Armin [Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Fraile Rodriguez, Arantxa [Departament de Fisica Fonamental and Institut de Nanociencia i Nanotecnologia (IN2UB), Universitat de Barcelona, 08028 Barcelona (Spain); El Moussaoui, Souliman; Balan, Ana; Buzzi, Michele; Raabe, Joerg [Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Nolting, Frithjof, E-mail: frithjof.nolting@psi.ch [Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Time resolved PEEM set up using a femtosecond laser as the pump pulse. Black-Right-Pointing-Pointer Magnetization vectometry based on advanced computer algorithms enables the determination of the in-plane and out-of-plane magnetization directions in micro and nanostructures. Black-Right-Pointing-Pointer Special sample holders allow measurements in applied magnetic fields to study the hysteresis loop of nanoparticles and to image in up to 40 mT out-of-plane magnetic fields. -- Abstract: Polarization dependent X-ray absorption spectroscopy and microscopy enables the element selective investigation of magnetic systems at the nanoscale. At the Swiss Light Source a photoemission electron microscope is used for the study of a broad variety of systems. Here, a review of recent activities is presented with a focus on instrumental and analytical developments. A new procedure for the 3 dimensional determination of the magnetization vector has been developed, and is demonstrated for GdFeCo microstructures displaying in-plane and out-of-plane domains, and sub-20 nm Fe nanoparticles. The recent progress for measurements in applied magnetic fields is presented and a new set-up for time-resolved measurements employing femtosecond laser pulses is described.

  16. A statistical correlation of sunquakes based on their seismic, white light, and X-ray emission

    CERN Document Server

    Buitrago-Casas, J C; Lindsey, C; Calvo-Mozo, B; Krucker, S; Glesener, L; Zharkov, S

    2015-01-01

    Several mechanisms have been proposed to explain the transient seis- mic emission, i.e., sunquakes, from some solar flares. Some theories associate high-energy electrons and/or white-light emission with sunquakes. High-energy charged particles and their subsequent heating of the photosphere and/or chro- mosphere could induce acoustic waves in the solar interior. We carried out a correlative study of solar flares with emission in hard-X rays (HXRs), enhanced continuum emission at 6173{\\AA}, and transient seismic emission. We selected those flares observed by RHESSI (Reuven Ramaty High Energy Solar Spectroscopic Imager) with a considerable flux above 50 keV between January 1, 2010 and June 26, 2014. We then used data from the Helioseismic and Magnetic Imager onboard the Solar Dynamic Observatory (SDO/HMI) to search for excess visible continuum emission and new sunquakes not previously reported. We found a total of 18 sunquakes out of 75 investigated. All of the sunquakes were associated with a enhancement of th...

  17. Light-induced atom desorption from glass surfaces characterized by X-ray photoelectron spectroscopy

    Science.gov (United States)

    Kumagai, Ryo; Hatakeyama, Atsushi

    2016-07-01

    We analyzed the surfaces of vitreous silica (quartz) and borosilicate glass (Pyrex) substrates exposed to rubidium (Rb) vapor by X-ray photoelectron spectroscopy (XPS) to understand the surface conditions of alkali metal vapor cells. XPS spectra indicated that Rb atoms adopted different bonding states in quartz and Pyrex. Furthermore, Rb atoms in quartz remained in the near-surface region, while they diffused into the bulk in Pyrex. For these characterized surfaces, we measured light-induced atom desorption (LIAD) of Rb atoms. Clear differences in time evolution, photon energy dependence, and substrate temperature dependence were found; the decay of LIAD by continuous ultraviolet irradiation for quartz was faster than that for Pyrex, a monotonic increase in LIAD with increasing photon energy from 1.8 to 4.3 eV was more prominent for quartz, and LIAD from quartz was more efficient at higher temperatures in the range from 300 to 580 K, while that from Pyrex was almost independent of temperature.

  18. Characterization of the X-ray light curve of the gamma Cas-like B1e star HD110432

    CERN Document Server

    Smith, Myron A; Motch, Christian

    2012-01-01

    HD 110432 (BZ Cru; B1Ve) is the brightest member of a small group of "gamma Cas analogs" that emit copious hard X-ray flux, punctuated by ubiquitous "flares." To characterize the X-ray time history of this star, we made a series of six RXTE multi-visit observations in 2010 and an extended observation with the XMM-Newton in 2007. We analyzed these new light curves along with three older XMM-Newton observations from 2002--2003. Distributed over five months, the RXTE observations were designed to search for long X-ray modulations over a few months. These observations indeed suggest the presence of a long cycle with P = 226 days and an amplitude of a factor of two. We also used X-ray light curves constructed from XMM-Newton observations to characterize the lifetimes, strengths, and interflare intervals of 1615 flare-like events in the light curves. After accounting for false positive events, we infer the presence of 955 (2002-2003) and 386 (2007) events we identified as flares. Similarly, as a control we measured...

  19. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... radiation like light or radio waves. X-rays pass through most objects, including the body. Once it ... organs, allow more of the x-rays to pass through them. As a result, bones appear white ...

  20. Light Dawns on Dark Gamma-ray Bursts

    Science.gov (United States)

    2010-12-01

    Gamma-ray bursts are among the most energetic events in the Universe, but some appear curiously faint in visible light. The biggest study to date of these so-called dark gamma-ray bursts, using the GROND instrument on the 2.2-metre MPG/ESO telescope at La Silla in Chile, has found that these gigantic explosions don't require exotic explanations. Their faintness is now fully explained by a combination of causes, the most important of which is the presence of dust between the Earth and the explosion. Gamma-ray bursts (GRBs), fleeting events that last from less than a second to several minutes, are detected by orbiting observatories that can pick up their high energy radiation. Thirteen years ago, however, astronomers discovered a longer-lasting stream of less energetic radiation coming from these violent outbursts, which can last for weeks or even years after the initial explosion. Astronomers call this the burst's afterglow. While all gamma-ray bursts [1] have afterglows that give off X-rays, only about half of them were found to give off visible light, with the rest remaining mysteriously dark. Some astronomers suspected that these dark afterglows could be examples of a whole new class of gamma-ray bursts, while others thought that they might all be at very great distances. Previous studies had suggested that obscuring dust between the burst and us might also explain why they were so dim. "Studying afterglows is vital to further our understanding of the objects that become gamma-ray bursts and what they tell us about star formation in the early Universe," says the study's lead author Jochen Greiner from the Max-Planck Institute for Extraterrestrial Physics in Garching bei München, Germany. NASA launched the Swift satellite at the end of 2004. From its orbit above the Earth's atmosphere it can detect gamma-ray bursts and immediately relay their positions to other observatories so that the afterglows could be studied. In the new study, astronomers combined Swift

  1. Sub-nanosecond time-resolved ambient-pressure X-ray photoelectron spectroscopy setup for pulsed and constant wave X-ray light sources.

    Science.gov (United States)

    Shavorskiy, Andrey; Neppl, Stefan; Slaughter, Daniel S; Cryan, James P; Siefermann, Katrin R; Weise, Fabian; Lin, Ming-Fu; Bacellar, Camila; Ziemkiewicz, Michael P; Zegkinoglou, Ioannis; Fraund, Matthew W; Khurmi, Champak; Hertlein, Marcus P; Wright, Travis W; Huse, Nils; Schoenlein, Robert W; Tyliszczak, Tolek; Coslovich, Giacomo; Robinson, Joseph; Kaindl, Robert A; Rude, Bruce S; Ölsner, Andreas; Mähl, Sven; Bluhm, Hendrik; Gessner, Oliver

    2014-09-01

    An apparatus for sub-nanosecond time-resolved ambient-pressure X-ray photoelectron spectroscopy studies with pulsed and constant wave X-ray light sources is presented. A differentially pumped hemispherical electron analyzer is equipped with a delay-line detector that simultaneously records the position and arrival time of every single electron at the exit aperture of the hemisphere with ~0.1 mm spatial resolution and ~150 ps temporal accuracy. The kinetic energies of the photoelectrons are encoded in the hit positions along the dispersive axis of the two-dimensional detector. Pump-probe time-delays are provided by the electron arrival times relative to the pump pulse timing. An average time-resolution of (780 ± 20) ps (FWHM) is demonstrated for a hemisphere pass energy E(p) = 150 eV and an electron kinetic energy range KE = 503-508 eV. The time-resolution of the setup is limited by the electron time-of-flight (TOF) spread related to the electron trajectory distribution within the analyzer hemisphere and within the electrostatic lens system that images the interaction volume onto the hemisphere entrance slit. The TOF spread for electrons with KE = 430 eV varies between ~9 ns at a pass energy of 50 eV and ~1 ns at pass energies between 200 eV and 400 eV. The correlation between the retarding ratio and the TOF spread is evaluated by means of both analytical descriptions of the electron trajectories within the analyzer hemisphere and computer simulations of the entire trajectories including the electrostatic lens system. In agreement with previous studies, we find that the by far dominant contribution to the TOF spread is acquired within the hemisphere. However, both experiment and computer simulations show that the lens system indirectly affects the time resolution of the setup to a significant extent by inducing a strong dependence of the angular spread of electron trajectories entering the hemisphere on the retarding ratio. The scaling of the angular spread with

  2. X-ray shout echoing through space

    Science.gov (United States)

    2004-01-01

    observatories around the world were pointing their instruments at this mysterious source in the sky, named GRB 031203, in the attempt to decipher its nature. Also ESA's X-ray observatory, XMM-Newton, joined the hunt and observed the source in detail, using its on-board European Photon Imaging Camera (EPIC). The fading X-ray emission from GRB 031203 - called the `afterglow' - is clearly seen in XMM-Newton's images. But much more stunning are the two rings, centred on the afterglow, which appear to expand thousand times faster than the speed of light. Dr. Simon Vaughan, of the University of Leicester, United Kingdom, leads an international team of scientists studying GRB 031203. He explains that these rings are what astronomers call an `echo'. They form when the X-rays from the distant gamma-ray burst shine on a layer of dust in our own Galaxy. "The dust scatters some of the X-rays, causing XMM-Newton to observe these rings, much in the same way as fog scatters the light from a car's headlights," said Vaughan. Although the afterglow is the brightest feature seen in XMM-Newton's images, the expanding echo is much more spectacular. "It is like a shout in a cathedral," Vaughan said. "The shout of the gamma-ray burst is louder, but the Galactic reverberation, seen as the rings, is much more beautiful." The rings seem to expand because the X-rays scattered by dust farther from the direction of GRB 031203 take longer to reach us than those hitting the dust closer to the line of sight. However, nothing can move faster than light. "This is precisely what we expect because of the finite speed of light," said Vaughan. "The rate of expansion that we see is just a visual effect." He and his colleagues explain that we see two rings because there are two thin sheets of dust between the source of the gamma-ray burst and Earth, one closer to us creating the wider ring and one further away where the smaller ring is formed. Since they know precisely at what speed the X-ray light travels in space

  3. Experimental measurements of the O15(alpha,gamma)Ne19 reaction rate vs. observations of type I X-ray bursts

    CERN Document Server

    Fisker, J L; Görres, J; Wiescher, M; Cooper, R L; Fisker, Jacob Lund; Tan, Wanpeng; Goerres, Joachim; Wiescher, Michael; Cooper, Randall L.

    2007-01-01

    Neutron stars in close binary star systems often accrete matter from their companion stars. Thermonuclear ignition of the accreted material in the atmosphere of the neutron star leads to a thermonuclear explosion which is observed as an X-ray burst occurring periodically between hours and days depending on the accretion rate. The ignition conditions are characterized by a sensitive interplay between the continuously accreting fuel supply and depletion by nuclear burning via the hot CNO cycles. Therefore the ignition depends critically on the hot CNO breakout reaction O15(alpha,gamma)Ne19 that regulates the flow between the beta-limited hot CNO cycle and the rapid proton capture process. Until recently, the O15(alpha,gamma)Ne19 reaction rate was not known experimentally and the theoretical estimates carried significant uncertainties. In this paper we report on the astrophysical consequences of the first measurement of this reaction rate on the thermonuclear instability that leads to type I X-ray bursts on accr...

  4. BURST TAILS FROM SGR J1550–5418 OBSERVED WITH THE ROSSI X-RAY TIMING EXPLORER

    Energy Technology Data Exchange (ETDEWEB)

    Muş, Sinem Şaşmaz; Gögüş, Ersin; Kaneko, Yuki; Chakraborty, Manoneeta; Aydın, Berk, E-mail: sinemsmus@sabanciuniv.edu [Sabancı University, Faculty of Engineering and Natural Sciences, Orhanlı Tuzla 34956 Istanbul (Turkey)

    2015-07-01

    We present the results of our extensive search using the Bayesian block method for long tails following short bursts from a magnetar, SGR J1550–5418, over all RXTE observations of the source. We identified four bursts with extended tails, most of which occurred during its 2009 burst active episode. The durations of tails range between ∼13 s and over 3 ks, which are much longer than the typical duration of bursts. We performed detailed spectral and temporal analyses of the burst tails. We find that the spectra of three tails show a thermal nature with a trend of cooling throughout the tail. We compare the results of our investigations with the properties of four other extended tails detected from SGR 1900+14 and SGR 1806–20 and suggest a scenario for the origin of the tail in the framework of the magnetar model.

  5. Lord of the Rings: A Kinematic Distance to Circinus X-1 from a Giant X-Ray Light Echo

    CERN Document Server

    Heinz, Sebastian; Braiding, Catherine; Brandt, William N; Jonker, Peter G; Sell, Paul; Fender, Robert P; Nowak, Michael A; Schulz, Norbert S

    2015-01-01

    Circinus X-1 exhibited a bright X-ray flare in late 2013. Follow-up observations with Chandra and XMM-Newton from 40 to 80 days after the flare reveal a bright X-ray light echo in the form of four well-defined rings with radii from 5 to 13 arcminutes, growing in radius with time. The large fluence of the flare and the large column density of interstellar dust towards Circinus X-1 make this the largest and brightest set of rings from an X-ray light echo observed to date. By deconvolving the radial intensity profile of the echo with the MAXI X-ray lightcurve of the flare we reconstruct the dust distribution towards Circinus X-1 into four distinct dust concentrations. By comparing the peak in scattering intensity with the peak intensity in CO maps of molecular clouds from the Mopra Southern Galactic Plane CO Survey we identify the two innermost rings with clouds at radial velocity ~ -74 km/s and ~ -81 km/s, respectively. We identify a prominent band of foreground photoelectric absorption with a lane of CO gas at...

  6. The Height of a White-Light Flare and its Hard X-Ray Sources

    Science.gov (United States)

    Oliveros, Juan-Carlos Martinez; Hudson, Hugh S.; Hurford, Gordon J.; Kriucker, Saem; Lin, R. P.; Lindsey, Charles; Couvidat, Sebastien; Schou, Jesper; Thompson, W. T.

    2012-01-01

    We describe observations of a white-light (WL) flare (SOL2011-02-24T07:35:00, M3.5) close to the limb of the Sun, from which we obtain estimates of the heights of the optical continuum sources and those of the associated hard X-ray (HXR) sources. For this purpose, we use HXR images from the Reuven Ramaty High Energy Spectroscopic Imager and optical images at 6173 Ang. from the Solar Dynamics Observatory.We find that the centroids of the impulsive-phase emissions in WL and HXRs (30 -80 keV) match closely in central distance (angular displacement from Sun center), within uncertainties of order 0".2. This directly implies a common source height for these radiations, strengthening the connection between visible flare continuum formation and the accelerated electrons. We also estimate the absolute heights of these emissions as vertical distances from Sun center. Such a direct estimation has not been done previously, to our knowledge. Using a simultaneous 195 Ang. image from the Solar-Terrestrial RElations Observatory spacecraft to identify the heliographic coordinates of the flare footpoints, we determine mean heights above the photosphere (as normally defined; tau = 1 at 5000 Ang.) of 305 +/- 170 km and 195 +/- 70 km, respectively, for the centroids of the HXR and WL footpoint sources of the flare. These heights are unexpectedly low in the atmosphere, and are consistent with the expected locations of tau = 1 for the 6173 Ang and the approx 40 keV photons observed, respectively.

  7. Karl Jaspers' phenomenology in the light of histological and X-ray metaphors.

    Science.gov (United States)

    Vlasova, Olga Alexandrovna; Beveridge, Allan

    2014-03-01

    The study considers the origins of Karl Jaspers' phenomenology. What did phenomenology mean to Jaspers and what was his personal perspective? What metaphors did he associate with it? This paper describes his phenomenological method by using the metaphors of histology and the X-ray. This perspective enables a better understanding, not only of the origins and essence of his phenomenology but also of its value for Jaspers himself. In Jaspers' daily life, he would have been familiar with microscopes and X-ray machines.

  8. Joint Spectral Analysis for Early Bright X-ray Flares of -Ray Bursts with Swift BAT and XRT Data

    Indian Academy of Sciences (India)

    Fang-Kun Peng; You-Dong Hu; Xiang-Gao Wang; Rui-Jing Lu; En-Wei Liang

    2014-09-01

    A joint spectral analysis for early bright X-ray flares that were simultaneously observed with Swift BAT and XRT are present. Both BAT and XRT lightcurves of these flares are correlated. Our joint spectral analysis shows that the radiations in the two energy bands are from the same spectral component, which can be well fitted with a single power-law. Except for the flares in GRBs 060904B and 100906A, the photon spectral indices are < 2.0, indicating the peak energies (p) of the prompt -rays should be above the high energy end of the BAT band.

  9. 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.

  10. Atomic physics with hard X-rays from high brilliance synchrotron light sources

    Energy Technology Data Exchange (ETDEWEB)

    Southworth, S.; Gemmell, D.

    1996-08-01

    A century after the discovery of x rays, the experimental capability for studying atomic structure and dynamics with hard, bright synchrotron radiation is increasing remarkably. Tempting opportunities arise for experiments on many-body effects, aspects of fundamental photon-atom interaction processes, and relativistic and quantum-electrodynamic phenomena. Some of these possibilities are surveyed in general terms.

  11. Inner Disk Structure of Dwarf Novae in the Light of X-ray Observations

    CERN Document Server

    Balman, S

    2014-01-01

    Diversity of the X-ray observations of dwarf nova are still not fully understood. I review the X-ray spectral characteristics of dwarf novae during the quiescence in general explained by cooling flow models and the outburst spectra that show hard X-ray emission dominantly with few sources that reveal soft X-ray/EUV blackbody emission. The nature of aperiodic time variability of brightness of dwarf novae shows band limited noise, which can be adequately described in the framework of the model of propagating fluctuations. The frequency of the break (1-6 mHz) indicates inner disk truncation of the optically thick disk with a range of radii (3.0-10.0)$\\times$10$^{9}$ cm. The RXTE and optical (RTT150) data of SS Cyg in outburst and quiescence reveal that the inner disk radius moves towards the white dwarf and receeds as the outburst declines to quiescence. A preliminary analysis of SU UMa indicates a similar behaviour. In addition, I find that the outburst spectra of WZ Sge shows two component spectrum of only har...

  12. Revisiting Evidence of Chaos in X-ray Light Curves: The Case of GRS 1915+105

    CERN Document Server

    Mannattil, Manu; Chakraborty, Sagar

    2016-01-01

    Nonlinear time series analysis has been widely used to search for signatures of low-dimensional chaos in light curves emanating from astrophysical bodies. A particularly popular example is the microquasar GRS 1915+105, whose irregular but systematic X-ray variability has been well studied using data acquired by the Rossi X-ray Timing Explorer (RXTE). With a view to building simpler models of X-ray variability, attempts have been made to classify the light curves of GRS 1915+105 as chaotic or stochastic. Contrary to some of the earlier suggestions, after careful analysis, we find no evidence for chaos or determinism in any of the GRS 1915+105 classes. The dearth of long and stationary data sets representing all the different variability classes of GRS 1915+105 make it a poor candidate for analysis using nonlinear time series techniques. We conclude that either very exhaustive data analysis with sufficiently long and stationary light curves should be performed keeping all the pitfalls of nonlinear time series a...

  13. Systematic Uncertainties in the Spectroscopic Measurements of Neutron-Star Masses and Radii from Thermonuclear X-ray Bursts. III. Absolute Flux Calibration

    CERN Document Server

    Guver, Tolga; Marshall, Herman; Psaltis, Dimitrios; Guainazzi, Matteo; Diaz-Trigo, Maria

    2015-01-01

    Many techniques for measuring neutron star radii rely on absolute flux measurements in the X-rays. As a result, one of the fundamental uncertainties in these spectroscopic measurements arises from the absolute flux calibrations of the detectors being used. Using the stable X-ray burster, GS 1826-238, and its simultaneous observations by Chandra HETG/ACIS-S and RXTE/PCA as well as by XMM-Newton EPIC-pn and RXTE/PCA, we quantify the degree of uncertainty in the flux calibration by assessing the differences between the measured fluxes during bursts. We find that the RXTE/PCA and the Chandra gratings measurements agree with each other within their formal uncertainties, increasing our confidence in these flux measurements. In contrast, XMM-Newton EPIC-pn measures 14.0$\\pm$0.3% less flux than the RXTE/PCA. This is consistent with the previously reported discrepancy with the flux measurements of EPIC-pn, compared to EPIC-MOS1, MOS2 and ACIS-S detectors. We also address the calibration uncertainty in the RXTE/PCA int...

  14. Multidimensional Modeling of Type I X-ray Bursts. II. Two-Dimensional Convection in a Mixed H/He Accretor

    CERN Document Server

    Malone, C M; Nonaka, A; Almgren, A S; Bell, J B

    2014-01-01

    Type I X-ray Bursts (XRBs) are thermonuclear explosions of accreted material on the surfaces of a neutron stars in low mass X-ray binaries. Prior to the ignition of a subsonic burning front, runaway burning at the base of the accreted layer drives convection that mixes fuel and heavy-element ashes. In this second paper in a series, we explore the behavior of this low Mach number convection in mixed hydrogen/helium layers on the surface of a neutron star using two-dimensional simulations with the Maestro code. Maestro takes advantage of the highly subsonic flow field by filtering dynamically unimportant sound waves while retaining local compressibility effects, such as those due to stratification and energy release from nuclear reactions. In these preliminary calculations, we find that the rp-process approximate network creates a convective region that is split into two layers. While this splitting appears artificial due to the approximations of the network regarding nuclear flow out of the breakout reaction 1...

  15. Intermediate long X-ray bursts from the ultra-compact binary candidate SLX1737-282

    DEFF Research Database (Denmark)

    Falanga, M.; Chenevez, Jérôme; Cumming, A.

    2008-01-01

    emission in the 3-100 keV energy band is studied with the INTEGRAL data. Results: The persistent emission is measured to be 0.5% Eddington luminosity. From the photospheric radius expansion observed during at least one burst we derive the source distance at 7.3 kpc assuming a pure helium atmosphere...

  16. The influence of the energy emitted by solar flare soft X-ray bursts on the propagation of their associated interplanetary shock waves

    Science.gov (United States)

    Pinter, S.; Dryer, M.

    1985-01-01

    The relationship between the thermal energy released from 29 solar flares and the propagation features of their associated interplanetary shock waves that were detected at 1 AU is investigated. The 29 interplanetary shock waves were identified unambiguously and their tracking from each solar flare was deduced by tracking their associated interplanetary type-II radio emission. The thermal energy released in the solar flares was estimated from the time-intensity profiles of 1-8 A soft X-ray bursts from each flare. A good relationship is found between the flares' thermal energy with the IP shock-waves' transient velocity and arrival time at the earth - that is, the largest flare energy released is associated with the faster shock waves. Finally, a possible scenario of formation of a shock wave during the early phase of the flare and its propagation features is discussed.

  17. Measurement of the 18Ne(a,p_0)21Na reaction cross section in the burning energy region for X-ray bursts

    CERN Document Server

    Salter, P J C; Davinson, T; Falou, H Al; Chen, A; Davids, B; Fulton, B R; Galinski, N; Howell, D; Lotay, G; Machule, P; Murphy, A StJ; Ruiz, C; Sjue, S; Taggart, M; Walden, P; Woods, P J

    2012-01-01

    The 18Ne(a,p)21Na reaction provides one of the main HCNO-breakout routes into the rp-process in X-ray bursts. The 18Ne(a,p_0)21Na reaction cross section has been measured for the first time in the Gamow energy region for peak temperatures T=2GK using the time-reversal approach in inverse kinematics. The astrophysical rate for ground-state to ground-state transitions was found to be a factor of 2 lower than Hauser-Feshbach theoretical predictions. Our reduced rate will affect the physical conditions under which breakout from the HCNO cycles occurs via the 18Ne(a,p)21Na reaction.

  18. Developments in synchrotron x-ray micro-tomography for in-situ materials analysis at the Advanced Light Source

    Science.gov (United States)

    Barnard, Harold S.; MacDowell, A. A.; Parkinson, D. Y.; Venkatakrishnan, S. V.; Panerai, F.; Mansour, N. N.

    2016-10-01

    The Advanced Light Source (ALS) is a third-generation synchrotron X-ray source that operates as a user facility with more than 40 beamlines hosting over 2000 users per year. Synchrotron sources like the ALS provide high quality X-ray beams, with flux that is several orders of magnitude higher than lab-based sources. This is particularly advantageous for dynamic applications because it allows for high-speed, high-resolution imaging and microscale tomography. The hard X-ray beamline 8.3.2 at the Advanced Light Source enables imaging of samples at high temperatures and pressures, with mechanical loading and other realistic conditions using environmental test cells. These test cells enable experimental observation of samples undergoing dynamic microstructural changes in-situ. We present recent instrumentation developments that allow for continuous tomography with scan rates approaching 1 Hz per 3D image. In addition, our use of iterative reconstruction techniques allows for improved image quality despite fewer images and low exposure times used during fast tomography compared to traditional Fourier reconstruction methods.

  19. X-ray optics design studies for the SLAC 1.5-15 A Linac Coherent Light Source (LCLS)

    CERN Document Server

    Tatchyn, R; Boyce, R; Fassò, A; Montgomery, J; Vylet, V; Walz, D; Yotam, R; Freund, A K; Howells, M

    1999-01-01

    In recent years, a number of systematic studies have been carried out on the design and R and D aspects of X-ray free-electron laser (XRFEL) schemes based on driving highly compressed electron bunches from a multi-GeV linac through long (30 m - 100+ m) undulators. These sources, when operated in the self-amplified spontaneous emission (SASE) mode, feature singularly high peak output power densities and frequently unprecedented combinations of phase-space and output-parameter values. This has led to correspondingly pivotal design challenges and opportunities for the optical materials, systems, components, and experimental configurations for transporting and utilizing this radiation. In this paper we summarize the design and R and D status of the X-ray optics section of the SLAC Linac Coherent Light Source (LCLS), a 1.5 Angstrom SASE FEL driven by the last kilometer of the SLAC 3-kilometer S-band linac.

  20. Enhancement of x-ray yields from heteronuclear cluster plasmas irradiated by intense laser light

    Energy Technology Data Exchange (ETDEWEB)

    Jha, J; Mathur, D; Krishnamurthy, M [Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400 005 (India)

    2005-09-28

    We report a new method to enhance the x-ray emission from nano-cluster plasmas formed upon irradiation by intense femtosecond-duration laser pulses. Our experiments demonstrate that when Ar clusters are doped with H{sub 2}O the time-integrated yield of Ar K x-ray emission is enhanced by approximately 12-fold in comparison to that obtained from pure Ar clusters under otherwise identical experimental conditions. A significant alteration in the time-dependent electron density is achieved by the presence of an H{sub 2}O dopant, and this could be the possible reason for the enhancement that is observed. (letter to the editor)

  1. Emphysema early diagnosis using X-ray diffraction enhanced imaging at synchrotron light source

    OpenAIRE

    Dong, Linan; Li, Jun; Jian, Wushuai; Zhang, Lu; Wu, Mingshu; Shi, Hongli; Luo, Shuqian

    2014-01-01

    Background Chronic obstructive pulmonary disease (COPD) is one of the leading causes of morbidity and mortality worldwide, and emphysema is a common component of COPD. Currently, it is very difficult to detect early stage emphysema using conventional radiographic imaging without contrast agents, because the change in X-ray attenuation is not detectable with absorption-based radiography. Compared with the absorption-based CT, phase contrast imaging has more advantages in soft tissue imaging, b...

  2. The pre-collimator for the ASTRO-H x-ray telescopes: shielding from stray lights

    Science.gov (United States)

    Mori, Hideyuki; Maeda, Yoshitomo; Ishida, Manabu; Sato, Takuro; Ichihara, Kou; Tomikawa, Kazuki; Kunieda, Hideyo; Tawara, Yuzuru; Sugita, Satoshi; Watanabe, Tsuyoshi; Torii, Tatsuharu; Tachibana, Kenji; Awaki, Hisamitsu; Okajima, Takashi; Mochida, Masayuki; Kawabata, Eiji

    2012-09-01

    We report recent progresses on the fabrication of pre-collimators (PCs). The PCs are designed to mitigate stray lights for X-ray telescopes to be onboard ASTRO-H. Each PC consists of cylindrical aluminum shells (blades) wiht varying radii of 60-225 mm, alignment frames to guilde the blade positions, and the bade housing body. The alignment frame and the housing are made of Aluminum 6061 and 7075 alloy, respectively. Heat-forming process is introduced to the production to stabilize the blade shape in orbit. Precise curvature of radius (tolerance of 1mm) and the linearity along with the direction of incident X-rays (P.V. shell to reduce off-axis X-ray photons that leads to a "ghost" image within the detector field of view. In September 2010, the PC design--its height, thickness, and material of blades--was fixed and we produced the engineering model (EM) for the Soft X-ray Telescopes (SXTs). Since then, vibration tests for the EM PC unit are carried out twice, verifying that the PC has sufficient structural strength to withstand severe conditions during its launch. The EM PC is also installed onto the SXT mirror housing fabricated at the NASA's GSFC to validate our PC assembly method without any loss of thetelescope's effective aperture area. Since August 2011, we have been manusfacturing the PC blades for the flight models. We hereby show the manufacturing processes and also results of stray-light measurement without PCs for the SXT EM (obtained at ISAS 30m beamline facility) and the HXT FM (obtained at SPring-8 synchrotron radiation facility).

  3. The X-ray light curve of the massive colliding wind Wolf-Rayet + O binary WR 21a

    Science.gov (United States)

    Gosset, Eric; Nazé, Yaël

    2016-05-01

    Our dedicated XMM-Newton monitoring, as well as archival Chandra and Swift datasets, were used to examine the behaviour of the WN5h+O3V binary WR 21a at high energies. For most of the orbit, the X-ray emission exhibits few variations. However, an increase in strength of the emission is seen before periastron, following a 1 /D relative trend, where D is the separation between both components. This increase is rapidly followed by a decline due to strong absorption as the Wolf-Rayet (WR) comes in front. The fitted local absorption value appears to be coherent with a mass-loss rate of about 1 × 10-5 M⊙ yr-1 for the WR component. However, absorption is not the only parameter affecting the X-ray emission at periastron as even the hard X-ray emission decreases, suggesting a possible collapse of the colliding wind region near to or onto the photosphere of the companion just before or at periastron. An eclipse may appear as another potential scenario, but it would be in apparent contradiction with several lines of evidence, notably the width of the dip in the X-ray light curve and the absence of variations in the UV light curve. Afterwards, the emission slowly recovers, with a strong hysteresis effect. The observed behaviour is compatible with predictions from general wind-wind collision models although the absorption increase is too shallow. Based on observations collected at ESO as well as with Swift, Chandra, and the ESA science mission XMM-Newton, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and the USA (NASA).

  4. NuSTAR Observation Of A Type I X-Ray Burst From GRS 1741.9-2853

    DEFF Research Database (Denmark)

    Barriere, Nicolas M.; Krivonos, Roman; Tomsick, John A.

    2015-01-01

    of the burst, reminiscent of the detection by Waki et al. We propose that the line, if real, is formed in the wind above the photosphere of the NS by a resonant K alpha transition from H-like Cr gravitationally redshifted by a factor 1 + z = 1.09, corresponding to a radius range of 29.0-41.4 km for a mass...

  5. Use of a Synchrotron Radiation X-Ray Microprobe for Elemental Analysis at the National Synchrotron Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, B. M.

    1980-04-01

    The National Synchrotron Light Source (NSLS) is a facility consisting of a 700 MeV and a 2.5 GeV electron storage ring and dedicated to providing synchrotron radiation in the energy range from the vacuum ultraviolet to high energy x rays. Some of the properties of synchrotron radiation that contribute to its usefulness for x-ray fluorescence are: a continuous, tunable energy spectrum, strong collimation in the horizontal plane, high polarization in the storage ring plane, and relatively low energy deposition. The highest priority is for the development of an x-ray microprobe beam line capable of trace analysis in the parts per million range with spatial resolution as low as one micrometer. An eventual capability for bulk sample analysis is also planned with sensitivities in the more favorable cases being as low as 50 parts per billion in dry biological tissue. The microprobe technique has application to a variety of fields including the geological, medical, materials and environmental sciences. Examples of investigations include multielemental trace analysis across grain boundaries for the study of diffusion and cooling processes in geological and materials sciences samples; in leukocytes and other types of individual cells for studying the relationship between trace element concentrations and disease or nutrition; and in individual particles in air pollution samples.

  6. X-ray imaging of subsurface dynamics in high-Z materials at the Diamond Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Eakins, D. E., E-mail: d.eakins@imperial.ac.uk; Chapman, D. J. [Institute of Shock Physics, Imperial College London, London SW7 2BZ (United Kingdom)

    2014-12-15

    In this paper, we describe a new approach enabling study of subsurface dynamics in high-Z materials using the unique combination of high-energy synchrotron X-rays, a hybrid bunch structure, and a new dynamic loading platform. We detail the design and operation of the purpose-built, portable small bore gas-gun, which was installed on the I12 high-energy beamline at the Diamond Light Source and used to drive compression waves into solid and porous metal targets. Using a hybrid bunch structure and broadband X-ray pulses of up to 300 keV, radiographic snapshots were captured during various dynamic deformation processes in cm-scale specimens, thereby contributing to a more complete understanding of the evolution of mesoscale damage. Importantly, we highlight strategies for overcoming the challenges associated with using high-energy X-rays, and suggest areas for improvement needed to advance dynamic imaging through large-scale samples of relevance to engineering scenarios. These preliminary measurements demonstrate the feasibility of probing highly transient phenomena using the presented methodology.

  7. X-ray imaging of subsurface dynamics in high-Z materials at the Diamond Light Source

    Science.gov (United States)

    Eakins, D. E.; Chapman, D. J.

    2014-12-01

    In this paper, we describe a new approach enabling study of subsurface dynamics in high-Z materials using the unique combination of high-energy synchrotron X-rays, a hybrid bunch structure, and a new dynamic loading platform. We detail the design and operation of the purpose-built, portable small bore gas-gun, which was installed on the I12 high-energy beamline at the Diamond Light Source and used to drive compression waves into solid and porous metal targets. Using a hybrid bunch structure and broadband X-ray pulses of up to 300 keV, radiographic snapshots were captured during various dynamic deformation processes in cm-scale specimens, thereby contributing to a more complete understanding of the evolution of mesoscale damage. Importantly, we highlight strategies for overcoming the challenges associated with using high-energy X-rays, and suggest areas for improvement needed to advance dynamic imaging through large-scale samples of relevance to engineering scenarios. These preliminary measurements demonstrate the feasibility of probing highly transient phenomena using the presented methodology.

  8. X-ray imaging of subsurface dynamics in high-Z materials at the Diamond Light Source.

    Science.gov (United States)

    Eakins, D E; Chapman, D J

    2014-12-01

    In this paper, we describe a new approach enabling study of subsurface dynamics in high-Z materials using the unique combination of high-energy synchrotron X-rays, a hybrid bunch structure, and a new dynamic loading platform. We detail the design and operation of the purpose-built, portable small bore gas-gun, which was installed on the I12 high-energy beamline at the Diamond Light Source and used to drive compression waves into solid and porous metal targets. Using a hybrid bunch structure and broadband X-ray pulses of up to 300 keV, radiographic snapshots were captured during various dynamic deformation processes in cm-scale specimens, thereby contributing to a more complete understanding of the evolution of mesoscale damage. Importantly, we highlight strategies for overcoming the challenges associated with using high-energy X-rays, and suggest areas for improvement needed to advance dynamic imaging through large-scale samples of relevance to engineering scenarios. These preliminary measurements demonstrate the feasibility of probing highly transient phenomena using the presented methodology.

  9. Toward Control of Matter: Basic Energy Science Needs for a New Class of X-Ray Light Sources

    Energy Technology Data Exchange (ETDEWEB)

    Arenholz, Elke; Belkacem, Ali; Cocke, Lew; Corlett, John; Falcone, Roger; Fischer, Peter; Fleming, Graham; Gessner, Oliver; Hasan, M. Zahid; Hussain, Zahid; Kevan, Steve; Kirz, Janos; McCurdy, Bill; Nelson, Keith; Neumark, Dan; Nilsson, Anders; Siegmann, Hans; Stocks, Malcolm; Schafer, Ken; Schoenlein, Robert; Spence, John; Weber, Thorsten

    2008-09-24

    Over the past quarter century, light-source user facilities have transformed research in areas ranging from gas-phase chemical dynamics to materials characterization. The ever-improving capabilities of these facilities have revolutionized our ability to study the electronic structure and dynamics of atoms, molecules, and even the most complex new materials, to understand catalytic reactions, to visualize magnetic domains, and to solve protein structures. Yet these outstanding facilities still have limitations well understood by their thousands of users. Accordingly, over the past several years, many proposals and conceptual designs for"next-generation" x-ray light sources have been developed around the world. In order to survey the scientific problems that might be addressed specifically by those new light sources operating below a photon energy of about 3 keV and to identify the scientific requirements that should drive the design of such facilities, a workshop"Science for a New Class of Soft X-Ray Light Sources" was held in Berkeley in October 2007. From an analysisof the most compelling scientific questions that could be identified and the experimental requirements for answering them, we set out to define, without regard to the specific technologies upon which they might be based, the capabilities such light sources would have to deliver in order to dramatically advance the state of research in the areas represented in the programs of the Department of Energy's Office of Basic Energy Sciences (BES). This report is based on the workshop presentations and discussions.

  10. Absence of interaction between X-rays and UV light in inducing ouabain- and thioguanine-resistant mutants in Chinese hamster cells.

    Science.gov (United States)

    Cleaver, J E

    1978-11-01

    Chinese hamster ovary cells were irradiated with X-rays at times from 0 to 17 h before being irradiated with ultraviolet (UV) light. No synergism was observed between the two radiations for the production of mutants resistant to either ouabain or 6-thioguanine. These experiments were designed to test whether X-rays induced an error-prone repair system that would increase the frequency of mutations produced by UV light, but no such system was detected.

  11. Search for the light dark matter with an X-ray spectrometer

    CERN Document Server

    Boyarsky, A; Neronov, A; Ruchayskiy, O; Boyarsky, Alexey; Herder, Jan Willem den; Neronov, Andrey; Ruchayskiy, Oleg

    2007-01-01

    Sterile neutrinos with the mass in the keV range are interesting warm dark matter (WDM) candidates. The restrictions on their parameters (mass and mixing angle) obtained by current X-ray missions (XMM-Newton or Chandra) can only be improved by less than an order of magnitude in the near future. Therefore the new strategy of search is needed. We compare the sensitivities of existing and planned X-ray missions for the detection of WDM particles with the mass ~1-20 keV. We show that existing technology allows an improvement in sensitivity by a factor of 100. Namely, two different designs can achieve such an improvement: [A] a spectrometer with the high spectral resolving power of 0.1%, wide (steradian) field of view, with small effective area of about cm^2 (which can be achieved without focusing optics) or [B] the same type of spectrometer with a smaller (degree) field of view but with a much larger effective area of 10^3 cm^2 (achieved with the help of focusing optics). To illustrate the use of the "type A" des...

  12. Light-induced changes in an alkali metal atomic vapor cell coating studied by X-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hibberd, A. M.; Bernasek, S. L. [Department of Chemistry, Princeton University, Princeton, New Jersey 08544 (United States); Seltzer, S. J. [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Balabas, M. V. [Department of Physics, Saint-Petersburg State University, St. Petersburg 198504 (Russian Federation); Morse, M. [Department of Materials Science Engineering, Boise State University, Boise, Idaho 83725 (United States); Budker, D. [Department of Physics, University of California, Berkeley, California 94720-7300 (United States); Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2013-09-07

    The light-induced desorption of Rb atoms from a paraffin coating is studied with depth-profiling X-ray photoelectron spectroscopy (XPS) using tunable synchrotron radiation. Following Rb exposure, shifts of the C1s signal to higher binding energies, as well as the appearance of lower binding energy components in the O1s region, were observed. These effects were diminished after irradiation with desorbing light. Additionally, following desorbing-light irradiation, changes in the depth-dependent concentration of carbon were observed. These observations offer an insight into the microscopic changes that occur during light-induced atomic desorption and demonstrate the utility of XPS in understanding atom-coating interactions.

  13. VUV and X-ray coherent light with tunable polarization from single-pass free-electron lasers

    CERN Document Server

    Spezzani, C; Diviacco, B; Ferrari, E; Geloni, G; Karantzoulis, E; Mahieu, B; Vento, M; De Ninno, G

    2011-01-01

    Tunable polarization over a wide spectral range is a required feature of light sources employed to investigate the properties of local symmetry in both condensed and low-density matter. Among new-generation sources, free-electron lasers possess a unique combination of very attractive features, as they allow to generate powerful and coherent ultra-short optical pulses in the VUV and X-ray spectral range. However, the question remains open about the possibility to freely vary the light polarization of a free-electron laser, when the latter is operated in the so-called nonlinear harmonic-generation regime. In such configuration, one collects the harmonics of the free-electron laser fundamental emission, gaining access to the shortest possible wavelengths the device can generate. In this letter we provide the first experimental characterization of the polarization of the harmonic light produced by a free-electron laser and we demonstrate a method to obtain tunable polarization in the VUV and X-ray spectral range....

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

    Science.gov (United States)

    Langer, S. H.; Petrosian, V.

    1976-01-01

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

  15. High-precision soft x-ray polarimeter at Diamond Light Source

    Science.gov (United States)

    Wang, H.; Dhesi, S. S.; Maccherozzi, F.; Cavill, S.; Shepherd, E.; Yuan, F.; Deshmukh, R.; Scott, S.; van der Laan, G.; Sawhney, K. J. S.

    2011-12-01

    The development and performance of a high-precision polarimeter for the polarization analysis in the soft x-ray region is presented. This versatile, high-vacuum compatible instrument is supported on a hexapod to simplify the alignment with a resolution less than 5 μrad, and can be moved with its own independent control system easily between different beamlines and synchrotron facilities. The polarimeter can also be used for the characterization of reflection and transmission properties of optical elements. A W/B4C multilayer phase retarder was used to characterize the polarization state up to 1200 eV. A fast and accurate alignment procedure was developed, and complete polarization analysis of the APPLE II undulator at 712 eV has been performed.

  16. High-precision soft x-ray polarimeter at Diamond Light Source.

    Science.gov (United States)

    Wang, H; Dhesi, S S; Maccherozzi, F; Cavill, S; Shepherd, E; Yuan, F; Deshmukh, R; Scott, S; van der Laan, G; Sawhney, K J S

    2011-12-01

    The development and performance of a high-precision polarimeter for the polarization analysis in the soft x-ray region is presented. This versatile, high-vacuum compatible instrument is supported on a hexapod to simplify the alignment with a resolution less than 5 μrad, and can be moved with its own independent control system easily between different beamlines and synchrotron facilities. The polarimeter can also be used for the characterization of reflection and transmission properties of optical elements. A W/B(4)C multilayer phase retarder was used to characterize the polarization state up to 1200 eV. A fast and accurate alignment procedure was developed, and complete polarization analysis of the APPLE II undulator at 712 eV has been performed.

  17. National synchrotron light source user's manual: Guide to the VUV and x-ray beamlines: Third edition

    Energy Technology Data Exchange (ETDEWEB)

    Gmuer, N.F.; Thomlinson, W.; White-DePace, S.

    1989-01-01

    This report contains information on the following topics: A Word on the Writing of Beamline Descriptions; Beamline Equipment Utilization for General Users; the Vacuum Ultraviolet (VUV) Storage Ring and Beamlines; VUV Beamline Descriptions--An Explanation; VUV Beamline Descriptions; X-Ray Storage Ring and Beamlines; X-Ray Beamline Descriptions--An Explanation; and X-Ray Beamline Descriptions.

  18. 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 ...

  19. 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 ...

  20. Soft X-ray Extended Emissions of Short Gamma-Ray Bursts as Electromagnetic Counterparts of Compact Binary Mergers; Possible Origin and Detectability

    CERN Document Server

    Nakamura, Takashi; Nakauchi, Daisuke; Suwa, Yudai; Sakamoto, Takanori; Kawai, Nobuyuki

    2013-01-01

    We investigate the possible origin of extended emissions (EE) of short gamma-ray bursts (SGRBs) with an isotropic energy of $\\sim 10^{50\\mbox{-}51} \\ \\rm erg$ and a duration of $\\sim 100 \\ \\rm s$, based on the compact binary (neutron star (NS)-NS or NS-black hole (BH)) merger scenario. We analyze the evolution of magnetized neutrino-dominated accretion disks of mass $\\sim 0.1 \\ M_\\odot$ around BHs formed after the mergers, and estimate the power of relativistic outflows via the Blandford-Znajek (BZ) process. We show that a rotation energy of the BH up to $\\sim 10^{53} \\ \\rm erg$ can be extracted with a time scale of $\\sim 100 \\ \\rm s$ with a disk viscosity parameter of $\\alpha \\sim 0.01$. Such a BZ power dissipates by clashing with non-relativistic pre-ejected matter of mass $M \\sim 10^{-(2\\mbox{-}4)} \\ M_\\odot$, and form a mildly relativistic fireball. We show that the dissipative photospheric emissions from such fireballs are likely in soft X-ray band ($1\\mbox{-}10 \\ \\rm keV$) for $M \\sim 10^{-2} M_\\odot$ p...

  1. Correlative cryogenic tomography of cells using light and soft x-rays.

    Science.gov (United States)

    Smith, Elizabeth A; Cinquin, Bertrand P; Do, Myan; McDermott, Gerry; Le Gros, Mark A; Larabell, Carolyn A

    2014-08-01

    Correlated imaging is the process of imaging a specimen with two complementary modalities, and then combining the two data sets to create a highly informative, composite view. A recent implementation of this concept has been the combination of soft x-ray tomography (SXT) with fluorescence cryogenic microscopy (FCM). SXT-FCM is used to visualize cells that are held in a near-native, cryopreserved. The resultant images are, therefore, highly representative of both the cellular architecture and molecular organization in vivo. SXT quantitatively visualizes the cell and sub-cellular structures; FCM images the spatial distribution of fluorescently labeled molecules. Here, we review the characteristics of SXT-FCM, and briefly discuss how this method compares with existing correlative imaging techniques. We also describe how the incorporation of a cryo-rotation stage into a cryogenic fluorescence microscope allows acquisition of fluorescence cryogenic tomography (FCT) data. FCT is optimally suited for correlation with SXT, since both techniques image the specimen in 3-D, potentially with similar, isotropic spatial resolution.

  2. First results of the resonant inelastic X-ray scattering station at the ADRESS beamline at the Swiss Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, Thorsten; Strocov, Vladimir; Schlappa, Justina; Patthey, Luc [Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Ghiringhelli, Giacomo; Piazzalunga, Andrea; Dallera, Claudia; Braicovich, Lucio [Politecnico di Milano (Italy); Wang, Xiaoqiang; Grioni, Marco [EPFL Lausanne (Switzerland)

    2008-07-01

    Resonant inelastic X-ray scattering (RIXS) is a powerful bulk-sensitive probe of the electronic structure of condensed matter with atomic and orbital sensitivity. It is an unique tool for determining the energy and symmetry of charge neutral electronic excitations (e.g. crystal field or spin-flip excitations) in strongly correlated materials. The ADvanced RESonant Spectroscopies (ADRESS) beamline at the Swiss Light Source (SLS) features advanced instrumentation for RIXS. This year it will be complemented by instrumentation for Angle-Resolved Photoelectron Spectroscopy. The RIXS station is equipped with a spectrometer (resolving power {approx}12000 for 1 keV) so-called SAXES (Super Advanced X-ray Emission Spectrograph) based on a variable line spacing spherical grating. The RIXS station is open since spring 2007 and was undergoing the operation tests during the 2nd half of 2007. We report on first results obtained with RIXS on transition metal monoxides (NiO, MnO and CuO) as reference compounds. These results demonstrate the capability of this set-up for RIXS studies on strongly correlated materials with unprecedented ultra-high resolution.

  3. Soft X-ray optics

    CERN Document Server

    Spiller, Eberhard A

    1993-01-01

    This text describes optics mainly in the 10 to 500 angstrom wavelength region. These wavelengths are 50 to 100 times shorter than those for visible light and 50 to 100 times longer than the wavelengths of medical x rays or x-ray diffraction from natural crystals. There have been substantial advances during the last 20 years, which one can see as an extension of optical technology to shorter wavelengths or as an extension of x-ray diffraction to longer wavelengths. Artificial diffracting structures like zone plates and multilayer mirrors are replacing the natural crystals of x-ray diffraction.

  4. Soft X-rays shedding light on thin-film solar cell surfaces and interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bär, M., E-mail: marcus.baer@helmholtz-berlin.de [Solar Energy Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), D-14109 Berlin (Germany); Institut für Physik und Chemie, Brandenburgische Technische Universität Cottbus, D-03046 Cottbus (Germany); Department of Chemistry, University of Nevada, Las Vegas (UNLV), Las Vegas, NV 89154 (United States); Pookpanratana, S. [Department of Chemistry, University of Nevada, Las Vegas (UNLV), Las Vegas, NV 89154 (United States); Weinhardt, L. [Department of Chemistry, University of Nevada, Las Vegas (UNLV), Las Vegas, NV 89154 (United States); Institute for Photon Science and Synchrotron Radiation, Karlsruhe Institute of Technology (KIT), D-76344 Eggenstein-Leopoldshafen (Germany); ANKA Synchrotron Radiation Facility, Karlsruhe Institute of Technology, D-76344 Eggenstein-Leopoldshafen (Germany); Wilks, R.G.; Schubert, B.A.; Marsen, B.; Unold, T. [Solar Energy Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), D-14109 Berlin (Germany); Blum, M.; Krause, S. [Department of Chemistry, University of Nevada, Las Vegas (UNLV), Las Vegas, NV 89154 (United States); Zhang, Y. [Department of Chemistry, University of Nevada, Las Vegas (UNLV), Las Vegas, NV 89154 (United States); Department of Physics, Xiamen University, Xiamen, Fujian 361005 (China); Ranasinghe, A. [Department of Chemistry, University of Nevada, Las Vegas (UNLV), Las Vegas, NV 89154 (United States); Ramanathan, K.; Repins, I.; Contreras, M.A. [National Renewable Energy Laboratory (NREL), Golden, CO 80401 (United States); Nishiwaki, S. [Institute for Energy Conversion (IEC), University of Delaware, Newark, DE 19716 (United States); and others

    2013-10-15

    Highlights: ► S/Se gradient-driven chemical interaction at the CdS/CIG(S)Se interface. ► Depth-dependent band gap in chalcopyrites. ► Band alignment at the CdS/Cu{sub 2}ZnSnS{sub 4} solar cell heterojunction. ► Post-deposition treatment induces intermixing in the CdTe/CdS solar cell structure. -- Abstract: Thin-film solar cells based on compound semiconductors consist of a multilayer structure with various interfaces and contain a multitude of elements and impurities, etc. A rapid progress of these photovoltaic technologies can only be achieved by an insight-driven optimization/development. Hence it is crucial to characterize and understand the relationship between the chemical and electronic properties of these components. This paper reviews some examples of our recent work characterizing compound semiconductor thin films using laboratory- and synchrotron-based electron and soft X-ray spectroscopic characterization methods. It is demonstrated how these different analytical techniques are extraordinarily powerful to reveal the material characteristics from many different perspectives, ultimately resulting in a comprehensive picture of the related electronic and chemical properties. As examples, the paper will discuss the electronic surface structure of chalcopyrite thin-film solar cell absorbers, the chemical structure of the CdS/chalcopyrite interface, present the band alignment at the CdS/kesterite interface, and report on how post-deposition treatments cause chemical interaction/interdiffusion processes in CdTe/CdS thin-film solar cell structures.

  5. X-ray plateaus followed by sharp drops in GRBs 060413, 060522,060607A and 080330: Further evidences for central engine afterglow from gamma-ray bursts

    Institute of Scientific and Technical Information of China (English)

    Xiao-Hui Zhang

    2009-01-01

    The X-ray afterglows of GRBs 060413, 060522, 060607A and 080330 are characterized by a plateau followed by a very sharp drop. The plateau could be explained within the framework of the external forward shock model but the sharp drop can not.We interpret the plateau as the afterglows of magnetized central engines, plausibly magnetars. In this model, the X-ray afterglows are powered by the internal magnetic energy dissipation and the sudden drop is caused by the collapse of the magnetar. Accordingly,the X-ray plateau photons should have a high linear polarization, which can be tested by future X-ray polarimetry.

  6. Heavy concerns about the light axino explanation of the 3.5 keV X-ray line

    Directory of Open Access Journals (Sweden)

    Stefano Colucci

    2015-11-01

    Full Text Available An unidentified 3.5 keV line from X-ray observations of galaxy clusters has been reported recently. Although still under scrutiny, decaying dark matter could be responsible for this signal. We investigate whether an axino with a mass of 7 keV could explain the line, keeping the discussion as model independent as possible. We point out several obstacles, which were overlooked in the literature, and which make the axino an unlikely candidate. The only viable scenario predicts a light metastable neutralino, with a mass between 0.1 and 10 GeV and a lifetime between 10−3 and 104 s.

  7. Light and Small-Angle X-Ray Diffraction from Opal-Like Structures: Transition from Two- to Three-Dimensional Regimes and Effects of Disorder

    NARCIS (Netherlands)

    Samusev, A.K.; Samusev, K.B.; Sinev, I.S.; Rybin, M.V.; Limonov, M.F.; Grigoryeva, N.A.; Grigoryeva, S.V.; Petukhov, A.V.

    2012-01-01

    Conclusions To summarize, in this chapter diffraction of light and x-rays on opal-like structures is considered. New methodological approaches to collection, processing, and interpretation of experimental data are presented. In particular, a novel representation of the light diffraction data in the

  8. Revealing a hard X-ray spectral component reverberating within one light hour of the central Supermassive Black Hole in Ark 564

    CERN Document Server

    Giustini, M; Reeves, J N; Miller, L; Legg, E; Kraemer, S B; George, I M

    2015-01-01

    Ark 564 (z=0.0247) is an X-ray bright NLS1. By using advanced X-ray timing techniques, Legg et al. (2012) discovered an excess of "delayed" emission in the hard X-ray band (4-7.5 keV) following about 1000 seconds after "flaring" light in the soft X-ray band (0.4-1 keV). We report on the X-ray spectral analysis of eight XMM-Newton and one Suzaku observation of Ark 564. High-resolution spectroscopy was performed with the RGS in the soft X-ray band, while broad-band spectroscopy was performed with the EPIC-pn and XIS/PIN instruments. We analysed time-averaged, flux-selected, and time-resolved spectra. Despite the large variability in flux, the broad band spectral shape of Ark 564 is not dramatically varying and can be reproduced either by a superposition of a power law and a blackbody emission, or by a Comptonized power law emission model. High resolution spectroscopy revealed the presence of ionised gas along the line of sight at the systemic redshift of the source, with a low column density and a range of ioni...

  9. X-ray imaging and imaging spectroscopy of fusion plasmas and light-source experiments with spherical optics and pixel array detectors

    Science.gov (United States)

    Hill, K. W.; Bitter, M.; Delgado-Aparicio, L.; Pablant, N. A.; Beiersdorfer, P.; Sanchez del Rio, M.; Zhang, L.

    2012-10-01

    High resolution (λ/Δλ ~10,000) 1D imaging x-ray spectroscopy using a spherically bent crystal and a 2D hybrid pixelarray detector (PAD) is used world wide for Doppler measurements of ion-temperature (Ti) and plasma flow-velocityprofiles in magnetic confinement fusion (MCF) plasmas. Meter sized plasmas are diagnosed with cm spatial resolution and 10 ms time resolution. This concept can also be used as a diagnostic of small sources, such as inertial confinement fusion (ICF) plasmas and targets on x-ray light source beam lines, with spatial resolution of microns. A new concept of using matched pairs of spherically bent crystals for monochromatic stigmatic 2D x-ray imaging of mm sized sources offers the possibility of spatial resolution of microns and large solid angle, relative to that achieved with pinhole imaging. Other potential applications of the 2D imaging schemes include x-ray lithography and x-ray microscopy for biological and materials science research. Measurements from MFE plasmas, as well as laboratory experiments and ray tracing computations validating the 1D imaging spectroscopy and 2D x-ray imaging techniques will be presented.

  10. Does There Exist a Relationship Between Acoustic and White-Light Emission in Hard-X ray Solar Flares?

    Science.gov (United States)

    Buitrago-Casas, J. C.; Martinez Oliveros, J. C.; Glesener, L.; Krucker, S.; Calvo-Mozo, B.

    2014-12-01

    Several mechanisms have been proposed to explain the observed seismicity during some solar flares. One theory associates high-energy electrons and white-light emission with sunquakes. This relationship is based on the back-warming model, where high-energy electrons and their subsequent heating of the photosphere induce acoustic waves in the solar interior. We carried out a correlative study of solar flares with emission in hard-X rays (HXRs) above 50 keV, enhanced white light emission at 6573Å, and acoustic sources. We selected those flares observed by RHESSI (Reuven Ramaty High Energy Solar Spectroscopic Imager) with a considerable flux in the 50-100 and 100-300 keV bands between January 1, 2010 and June 26, 2014. Additionally, we restricted the sample to flares close to disk center where it is observationally easiest to detect a sunquake. We then used data from the Helioseismic and Magnetic Imager onboard the Solar Dynamic Observatory (SDO/HMI) to search for white-light emission and helioseismic signatures. Finally, we calculated a coefficient of correlation for this set of dichotomic observables. We discuss the phenomenological connectivity between these physical quantities and the observational difficulties of detecting seismic signals and white-light radiation with terrestrial and space-borne observations.

  11. Blue light-dependent changes in loosely bound calcium in Arabidopsis mesophyll cells: an X-ray microanalysis study.

    Science.gov (United States)

    Łabuz, Justyna; Samardakiewicz, Sławomir; Hermanowicz, Paweł; Wyroba, Elżbieta; Pilarska, Maria; Gabryś, Halina

    2016-06-01

    Calcium is involved in the signal transduction pathway from phototropins, the blue light photoreceptor kinases which mediate chloroplast movements. The chloroplast accumulation response in low light is controlled by both phot1 and phot2, while only phot2 is involved in avoidance movement induced by strong light. Phototropins elevate cytosolic Ca(2+) after activation by blue light. In higher plants, both types of chloroplast responses depend on Ca(2+), and internal calcium stores seem to be crucial for these processes. Yet, the calcium signatures generated after the perception of blue light by phototropins are not well understood. To characterize the localization of calcium in Arabidopsis mesophyll cells, loosely bound (exchangeable) Ca(2+) was precipitated with potassium pyroantimonate and analyzed by transmission electron microscopy followed by energy-dispersive X-ray microanalysis. In dark-adapted wild-type Arabidopsis leaves, calcium precipitates were observed at the cell wall, where they formed spherical structures. After strong blue light irradiation, calcium at the apoplast prevailed, and bigger, multilayer precipitates were found. Spherical calcium precipitates were also detected at the tonoplast. After red light treatment as a control, the precipitates at the cell wall were smaller and less numerous. In the phot2 and phot1phot2 mutants, calcium patterns were different from those of wild-type plants. In both mutants, no elevation of calcium after blue light treatment was observed at the cell periphery (including the cell wall and a fragment of cytoplasm). This result confirms the involvement of phototropin2 in the regulation of Ca(2+) homeostasis in mesophyll cells.

  12. A dedicated superbend x-ray microdiffraction beamline for materials, geo-, and environmental sciences at the advanced light source

    Energy Technology Data Exchange (ETDEWEB)

    Advanced Light Source; Kunz, Martin; Tamura, Nobumichi; Chen, Kai; MacDowell, Alastair A.; Celestre, Richard S.; Church, Matthew M.; Fakra, Sirine; Domning, Edward E.; Glossinger, James M.; Kirschman, Jonathan L.; Morrison, Gregory Y.; Plate, Dave W.; Smith, Brian V.; Warwick, Tony; Padmore, Howard A.; Ustundag, Ersan; Yashchuk, Valeriy V.

    2009-03-24

    A new facility for microdiffraction strain measurements and microfluorescence mapping has been built on beamline 12.3.2 at the advanced light source of the Lawrence Berkeley National Laboratory. This beamline benefits from the hard x-radiation generated by a 6 T superconducting bending magnet (superbend) This provides a hard x-ray spectrum from 5 to 22 keV and a flux within a 1 mu m spot of ~;;5x109 photons/ s (0.1percent bandwidth at 8 keV). The radiation is relayed from the superbend source to a focus in the experimental hutch by a toroidal mirror. The focus spot is tailored bytwo pairs of adjustable slits, which serve as secondary source point. Inside the lead hutch, a pair of Kirkpatrick-Baez (KB) mirrors placed in a vacuum tank refocuses the secondary slit source onto the sample position. A new KB-bending mechanism with active temperature stabilization allows for more reproducible and stable mirror bending and thus mirror focusing. Focus spots around 1 um are routinely achieved and allow a variety of experiments, which have in common the need of spatial resolution. The effective spatial resolution (~;;0.2 mu m) is limited by a convolution of beam size, scan-stage resolution, and stage stability. A four-bounce monochromator consisting of two channel-cut Si(111) crystals placed between the secondary source and KB-mirrors allows for easy changes between white-beam and monochromatic experiments while maintaining a fixed beam position. High resolution stage scans are performed while recording a fluorescence emission signal or an x-ray diffraction signal coming from either a monochromatic or a white focused beam. The former allows for elemental mapping, whereas the latter is used to produce two-dimensional maps of crystal-phases, -orientation, -texture, and -strain/stress. Typically achieved strain resolution is in the order of 5x10-5 strain units. Accurate sample positioning in the x-ray focus spot is achieved with a commercial laser-triangulation unit. A Si

  13. Science Goals and First Light Analysis from the Miniature X-ray Solar Spectrometer (MinXSS) CubeSat

    Science.gov (United States)

    Caspi, Amir; Woods, Thomas N.; Warren, Harry; Chamberlin, Phillip C.; Jones, Andrew; Mason, James; McTiernan, James; Moore, Christopher; Palo, Scott; Solomon, Stanley

    2016-05-01

    The Miniature X-ray Solar Spectrometer (MinXSS) is a 3U CubeSat with deployment from the ISS planned in Q2 2016. Its goal is to measure the solar soft X-ray (SXR) spectral irradiance, an observational signature of hot plasma in the solar corona. Over the last few decades, there have been very few spectrally resolved observations from ~0.2 to ~4 keV (~0.3-6 nm). This range is sensitive to high-temperature plasma and contains many spectral lines (e.g., Mg, Si, Fe, S, Ar), the abundances of which probe plasma transport and provide valuable constraints on plasma heating mechanisms during both flares and quiescence. This solar SXR emission is primarily absorbed in the E-region of Earth's ionosphere, and the subsequently driven dynamical processes are still poorly understood, in large part because the energy distribution of the incident SXRs is not yet well characterized.MinXSS flies a miniature commercial off-the-shelf soft X-ray (SXR) spectrometer, the Amptek X123-SDD. The silicon drift detector has 0.5 mm fully depleted thickness and a 25 mm^2 physical area, with a ~16 micron Be entrance window; with on-board thermoelectric cooling and pulse pile-up rejection, it is sensitive to solar SXRs from ~0.5 to 30 keV with ~0.15 keV FWHM resolution. MinXSS also includes a broadband SXR photometer, providing an integrated intensity over a similar energy range for comparison, cross-calibration, and additional data, especially useful during more intense flares at the upper end of the X123 dynamic range.We present the MinXSS science goals for studying hot plasma in the solar corona, including impulsive flare heating and quiescent coronal heating, and the impact of the resultant SXR emission on Earth's ionosphere, thermosphere, and mesosphere. We present analysis of MinXSS first light results (depending on deployment date from the ISS), as well as modeling and predictions of future observations over the MinXSS 6-12 month mission lifetime.

  14. REACTION RATES OF {sup 64}Ge(p,γ){sup 65}As AND {sup 65}As(p,γ){sup 66}Se AND THE EXTENT OF NUCLEOSYNTHESIS IN TYPE I X-RAY BURSTS

    Energy Technology Data Exchange (ETDEWEB)

    Lam, Y. H.; He, J. J.; Wang, M.; Zhang, Y. H.; Zhou, X. H.; Xu, H. S. [Key Laboratory of High Precision Nuclear Spectroscopy, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Parikh, A. [Departament de Física i Enginyeria Nuclear, EUETIB, Universitat Politècnica de Catalunya, Barcelona E-08036 (Spain); Schatz, H.; Brown, B. A. [Department of Physics and Astronomy and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824-1321 (United States); Guo, B., E-mail: jianjunhe@impcas.ac.cn, E-mail: anuj.r.parikh@upc.edu, E-mail: schatz@nscl.msu.edu [China Institute of Atomic Energy, P.O. Box 275(10), Beijing 102413 (China)

    2016-02-10

    The extent of nucleosynthesis in models of type I X-ray bursts (XRBs) and the associated impact on the energy released in these explosive events are sensitive to nuclear masses and reaction rates around the {sup 64}Ge waiting point. Using the well known mass of {sup 64}Ge, the recently measured {sup 65}As mass, and large-scale shell model calculations, we have determined new thermonuclear rates of the {sup 64}Ge(p,γ){sup 65}As and {sup 65}As(p,γ){sup 66}Se reactions with reliable uncertainties. The new reaction rates differ significantly from previously published rates. Using the new data, we analyze the impact of the new rates and the remaining nuclear physics uncertainties on the {sup 64}Ge waiting point in a number of representative one-zone XRB models. We find that in contrast to previous work, when all relevant uncertainties are considered, a strong {sup 64}Ge rp-process waiting point cannot be ruled out. The nuclear physics uncertainties strongly affect XRB model predictions of the synthesis of {sup 64}Zn, the synthesis of nuclei beyond A = 64, the energy generation, and the burst light curve. We also identify key nuclear uncertainties that need to be addressed to determine the role of the {sup 64}Ge waiting point in XRBs. These include the remaining uncertainty in the {sup 65}As mass, the uncertainty of the {sup 66}Se mass, and the remaining uncertainty in the {sup 65}As(p,γ){sup 66}Se reaction rate, which mainly originates from uncertain resonance energies.

  15. Radiation-damage-free quantum crystallography and resolution-enhanced x-ray imaging techniques using quantum multipath interference of thermal light

    CERN Document Server

    Li, Zheng; Medvedev, Nikita; Wang, Fenglin; Chapman, Henry N; Shih, Yanhua

    2016-01-01

    Using higher order coherence of thermal light sources, we can achieve enhancement of resolution of standard x-ray imaging techniques, such as x-ray diffraction and phase contrast imaging. The cost of implementing such schemes is minimal comparing to the schemes using entangled two-photon pairs. The proposed diffractive quan- tum crystallography using multipath interference of thermal light can be eventually free of radiation damage, because the diffraction pattern could be formed by using low energy photons of optical wavelength. Thus it is promising to apply the proposed quantum crystallography scheme to nanocrystalline or non-crystalline samples that are too difficult to be crystallized.

  16. Pulse Phase Dependence of the Magnetar Bursts

    Indian Academy of Sciences (India)

    Chetana Jain; Anjan Dutta; Biswajit Paul

    2007-12-01

    We report here results from a study of X-ray bursts from 3 magnetar candidates (SGR 1806–20, SGR 1900+14 and AXP 1E 2259+586). We have searched for a pulse phase dependence of the X-ray burst rate from these sources. X-ray light curves were obtained with the Proportional Counter Array on-board the Rossi X-ray Timing Explorer during the periods of intense burst activity in these sources. On detailed analysis of the three sources, we found a very significant burst rate for all pulsar phases. However, some locations appear to produce bursts slightly more often, rendering the non-isotropic distribution. Only in the case of SGR 1900+14, there is a clear pulse phase dependence of burst rate.

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

    Institute of Scientific and Technical Information of China (English)

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

    2000-01-01

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

  18. Light output measurements and computational models of microcolumnar CsI scintillators for x-ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Nillius, Peter, E-mail: nillius@mi.physics.kth.se; Klamra, Wlodek; Danielsson, Mats [Royal Institute of Technology (KTH), Stockholm SE-100 44 (Sweden); Sibczynski, Pawel [National Centre for Nuclear Research, Otwock 05-400 (Poland); Sharma, Diksha; Badano, Aldo [Division of Imaging, Diagnostics, and Software Reliability, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, FDA, Silver Spring, Maryland 20993 (United States)

    2015-02-15

    Purpose: The authors report on measurements of light output and spatial resolution of microcolumnar CsI:Tl scintillator detectors for x-ray imaging. In addition, the authors discuss the results of simulations aimed at analyzing the results of synchrotron and sealed-source exposures with respect to the contributions of light transport to the total light output. Methods: The authors measured light output from a 490-μm CsI:Tl scintillator screen using two setups. First, the authors used a photomultiplier tube (PMT) to measure the response of the scintillator to sealed-source exposures. Second, the authors performed imaging experiments with a 27-keV monoenergetic synchrotron beam and a slit to calculate the total signal generated in terms of optical photons per keV. The results of both methods are compared to simulations obtained with hybridMANTIS, a coupled x-ray, electron, and optical photon Monte Carlo transport package. The authors report line response (LR) and light output for a range of linear absorption coefficients and describe a model that fits at the same time the light output and the blur measurements. Comparing the experimental results with the simulations, the authors obtained an estimate of the absorption coefficient for the model that provides good agreement with the experimentally measured LR. Finally, the authors report light output simulation results and their dependence on scintillator thickness and reflectivity of the backing surface. Results: The slit images from the synchrotron were analyzed to obtain a total light output of 48 keV{sup −1} while measurements using the fast PMT instrument setup and sealed-sources reported a light output of 28 keV{sup −1}. The authors attribute the difference in light output estimates between the two methods to the difference in time constants between the camera and PMT measurements. Simulation structures were designed to match the light output measured with the camera while providing good agreement with the

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

    Science.gov (United States)

    Langer, S. H.; Petrosian, V.

    1977-01-01

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

  20. Chest X Ray?

    Science.gov (United States)

    ... this page from the NHLBI on Twitter. Chest X Ray A chest x ray is a fast and painless imaging test ... tissue scarring, called fibrosis. Doctors may use chest x rays to see how well certain treatments are ...

  1. X-Rays

    Science.gov (United States)

    X-rays are a type of radiation called electromagnetic waves. X-ray imaging creates pictures of the inside of ... different amounts of radiation. Calcium in bones absorbs x-rays the most, so bones look white. Fat ...

  2. Medical X-Rays

    Science.gov (United States)

    ... Benefits The discovery of X-rays and the invention of CT represented major advances in medicine. X- ... in X-ray and CT Examinations — X-ray definition, dose measurement, safety precautions, risk, and consideration with ...

  3. Comparison of the time behavior in the separation of light and heavy materials in X-ray backscattered method as a diagnostic tool in inspection

    Energy Technology Data Exchange (ETDEWEB)

    Faezeh, Rahmani, E-mail: FRahmani@kntu.ac.ir [Department of Physics, K.N. Toosi University of Technology, Tehran (Iran, Islamic Republic of); Sepideh Sadat, Azimi [Radiation Application Department, Shahid Beheshti University, Tehran (Iran, Islamic Republic of); Esmaiel, Bayat; Vahid, Dost Mohammadi [Nuclear Science and Technology Research Institute (NSTR), Tehran (Iran, Islamic Republic of)

    2016-03-11

    X-ray backscattered method based on Compton backscattering is used in the inspection field. In contrast to transmission method, source and detectors are positioned on one side of the target, so in the situation that transmission inspection is difficult, X-ray backscattered method can be provided suitable data in the inspection field. Also, detection of hidden explosives and narcotic materials are very difficult or impossible in transmission methods. High intensity backscattered beam from light materials (low-Z), such as explosives and narcotics, in comparison to the heavy materials (high-Z), made this method as the strong technique in inspection. X-ray and gamma photons scattered by the light material (such as PE and PTFE) as well as heavy material (such as Fe and Cu) were studied using MCNPX2.6 Monte Carlo code. The results showed that rise time of pulse from light materials are slower than that of from heavy materials due to multi scattering of low energy photons in the light ones, so time expansion would occur in signals from light elements. If measurement is possible, the difference in time behavior can be used as a novel method in complementary diagnostic tool beside the use of pulse height in X-ray backscattered method.

  4. Effect of Aberration of Light in X-ray Free Electron Lasers

    CERN Document Server

    Geloni, Gianluca; Saldin, Evgeni

    2015-01-01

    We discuss the physics of a microbunched electron beam kicked by the dipole field of a corrector magnet by describing the kinematics of coherent undulator radiation after the kick. Particle tracking shows that the electron beam direction changes after the kick, while the orientation of the microbunching wavefront stays unvaried. Therefore, electrons motion and wavefront normal have different directions. Coherent radiation emission in a downstream undulator is expected to be dramatically suppressed as soon as the kick angle becomes larger than the divergence of the output radiation. In fact, according to conventional treatments, coherent radiation is emitted along the normal to the microbunching wavefront. Here we show that kinematics predicts a surprising effect. Namely, a description of coherent undulator radiation in the laboratory frame yields the radical notion that, due light aberration, strong coherent radiation is produced along the direction of the kick. We hold a recent FEL study made at the LCLS as ...

  5. Synchrotron Small-Angle X-Ray Scattering Investigation on Integral Membrane Protein Light-Harvesting Complex LH2 from Photosynthetic Bacterium Rhodopseudomonas Acidophila

    Institute of Scientific and Technical Information of China (English)

    DU Lu-Chao; WENG Yu-Xiang; HONG Xin-Guo; XIAN Ding-Chang; Kobayashi Katsumi

    2006-01-01

    @@ Structures of membrane protein in solution are different from that in crystal phase. We present the primary results of small angle x-ray scattering (SAXS) resolved topological structures of a light harvesting antenna membrane protein complex LH2 from photosynthetic bacteria Rhodopseudomonas acidophila in detergent solution for the first time. Our results show that the elliptical shape of the LH2 complex in solution clearly deviates from its circular structure in crystal phase determined by x-ray diffraction. This result provides an insight into the structure and function interplay in LH2.

  6. Evolution and Activity in the Solar Corona: A Comparison of Coronal and Chromospheric Structures Seen in Soft X-Rays, White Light and H-Alpha Emission

    Science.gov (United States)

    Bagenal, Fran

    2001-01-01

    The work completed under this project, 'Evolution and Activity in the Solar Corona: A Comparison of Coronal and Chromospheric Structures Seen in Soft X-Rays, White Light and H-Alpha Emission', includes the following presentations: (1) Analysis of H-alpha Observations of High-altitude Coronal Condensations; (2) Multi-spectral Imaging of Coronal Activity; (3) Measurement and Modeling of Soft X-ray Loop Arcades; (4) A Study of the Origin and Dynamics of CMEs; and various poster presentations and thesis dissertations.

  7. Single shot spatial and temporal coherence properties of the SLAC Linac Coherent Light Source in the hard x-ray regime.

    Science.gov (United States)

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

    2012-01-13

    We measured the transverse and longitudinal coherence properties of the Linac Coherent Light Source (LCLS) at SLAC in the hard x-ray regime at 9 keV photon energy on a single shot basis. Speckle patterns recorded in the forward direction from colloidal nanoparticles yielded the transverse coherence properties of the focused LCLS beam. Speckle patterns from a gold nanopowder recorded with atomic resolution allowed us to measure the shot-to-shot variations of the spectral properties of the x-ray beam. The focused beam is in the transverse direction fully coherent with a mode number close to 1. The average number of longitudinal modes behind the Si(111) monochromator is about 14.5 and the average coherence time τ(c)=(2.0±1.0) fc. The data suggest a mean x-ray pulse duration of (29±14)  fs behind the monochromator for (100±14) fc electron pulses.

  8. Confirming the 115.5-day periodicity in the X-ray light curve of ULX NGC 5408 X-1

    Institute of Scientific and Technical Information of China (English)

    Xu Han; Tao An; Jun-Yi Wang; Ji-Ming Lin; Ming-Jie Xie; Hai-Guang Xu; Xiao-Yu Hong; Sandor Frey

    2012-01-01

    The Swift/XRT light curve of the ultraluminous X-ray source NGC 5408 X-1 was re-analyzed with two new numerical approaches,the Weighted Wavelet Ztransform and CLEANest,and the results are different from previous studies.Both techniques detected a prominent periodicity with a time scale of 115.5 ± 1.5 days,in excellent agreement with the detection of the same periodicity first reported by Strohmayer.Monte Carlo simulations were employed to test the statisitical confidence of the 115.5-day periodicity,yielding a statistical significance of > 99.98% (or >3.8σ).The robust detection of the 115.5-day quasi-periodic oscillations,if they are due to the orbital motion of the binary,would infer a mass of a few thousand M⊙ for the central black hole,implying there is an intermediate-mass black hole in NGC 5408 X-1.

  9. Special pattern of endochondral ossification in human laryngeal cartilages: X-ray and light-microscopic studies on thyroid cartilage.

    Science.gov (United States)

    Claassen, Horst; Schicht, Martin; Sel, Saadettin; Paulsen, Friedrich

    2014-04-01

    Endochondral ossification is a process that also occurs in the skeleton of the larynx. Differences in the ossification mechanism in comparison to growth plates are not understood until now. To get deeper insights into this process, human thyroid cartilage was investigated by the use of X-rays and a series of light-microscopic stainings. A statistical analysis of mineralization was done by scanning areas of mineralized cartilage and of ossification. We detected a special mode of endochondral ossification which differs from the processes in growth plates. Thyroid cartilage ossifies very slowly and in a gender-specific manner. Compared with age-matched women, bone formation in thyroid cartilage of men is significantly higher in the age group 41-60 years. Endochondral ossification is prepared by internal changes of extracellular matrix leading to areas of asbestoid fibers with ingrowing cartilage canals. In contrast to growth plates, bone is deposited on large areas of mineralized cartilage, which appear at the rims of cartilage canals. Furthermore, primary parallel fibered bone was observed which was deposited on woven bone. The predominant bone type is cancellous bone with trabeculae, whereas compact bone with Haversian systems was seldom found. Trabeculae contain a great number of reversal and arresting lines meaning that the former were often reconstructed and that bone formation was arrested and resumed again with advancing age. It is hypothesized that throughout life trabeculae of ossified thyroid cartilage undergo adaptation to different loads due to the use of voice.

  10. Evidence of Bulk Acceleration of the GRB X-Ray Flare Emission Region

    Science.gov (United States)

    Uhm, Z. Lucas; Zhang, Bing

    2016-06-01

    Applying our recently developed generalized version of the high-latitude emission theory to the observations of X-ray flares in gamma-ray bursts (GRBs), here we present clear observational evidence that the X-ray flare emission region is undergoing rapid bulk acceleration as the photons are emitted. We show that both the observed X-ray flare light curves and the photon index evolution curves can be simultaneously reproduced within a simple physical model invoking synchrotron radiation in an accelerating emission region far from the GRB central engine. Such an acceleration process demands an additional energy dissipation source other than kinetic energy, which points toward a significant Poynting flux in the emission region of X-ray flares. As the X-ray flares are believed to share a similar physical mechanism as the GRB prompt emission, our finding here hints that the GRB prompt emission jets may also carry a significant Poynting flux in their emitting region.

  11. X-ray pulsar rush in 1998

    Energy Technology Data Exchange (ETDEWEB)

    Imanishi, K.; Tsujimoto, K.; Nishiuchi, Mamiko; Yokogawa, J.; Koyama, K. [Kyoto Univ., Faculty of Science, Kyoto (Japan)

    1999-08-01

    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 {approx} 10{sup 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)

  12. Solar flare hard and soft x ray relationship determined from SMM HXRBS and BCS data

    Science.gov (United States)

    Toot, G. David

    1989-01-01

    The exact nature of the solar flare process is still somewhat a mystery. A key element to understanding flares if the relationship between the hard x rays emitted by the most energetic portions of the flare and the soft x rays from other areas and times. This relationship was studied by comparing hard x ray light curved from the Hard X-Ray Burst Spectrometer (HXRBS) with the soft x ray light curve and its derivation from the Bent Crystal Spectrometer (BCS) which is part of the X-Ray Polychrometer (XRP), these instruments being on the Solar Maximum Mission spacecraft (SMM). Data sample was taken from flares observed with the above instruments during 1980, the peak of the previous maximum of solar activity. Flares were chosen based on complete coverage of the event by several instruments. The HXRBS data covers the x ray spectrum from about 25 keV to about 440 keV in 15 spectral channels, while the BCS data used covers a region of the Spectrum around 3 angstroms including emission from the Ca XIX ion. Both sets of data were summed over their spectral ranges and plotted against time at a maximum time resolution of around 3 seconds. The most popular theory of flares holds that a beam of electrons produces the hard x rays by bremsstrahlung while the soft x rays are the thermal response to this energy deposition. The question is whether the rate of change of soft x ray emission might reflect the variability of the electron beam and hence the variability of the hard x rays. To address this, we took the time derivative of the soft x ray light curve and compared it to the hard flares, 12 of them showed very closed agreement between the soft x ray derivative and the hard x ray light curve. The other five did not show this behavior but were similar to each other in general soft x ray behavior. Efforts to determine basic differences between the two kinds of flares continue. In addition the behavior of soft x ray temperature of flares was examined.

  13. INTEGRAL monitoring of the X-ray burster XTE J1739-285

    DEFF Research Database (Denmark)

    Sánchez-Fernández, C.; Kuulkers, E.; Chenevez, Jérôme;

    2008-01-01

    XTE J1739-285 is a recurrent X-ray transient first discovered by INTEGRAL as an X-ray burster. We have carried out a systematic search for X-ray bursts at various levels of accretion rate onto the Neutron Star surface during the source outbursts in 2005 and 2006. A total of 25 X-ray bursts were f...

  14. Discovery of periodic dips in the light curve of GX 13+1: the X-ray orbital ephemeris of the source

    CERN Document Server

    Iaria, R; Burderi, L; Riggio, A; D'Ai, A; Robba, N R

    2013-01-01

    The bright low-mass X-ray binary (LMXB) GX 13+1 is one of the most peculiar Galactic binary systems. A periodicity of 24.27 d with a formal statistical error of 0.03 d was observed in its power spectrum density obtained with RXTE All Sky Monitor (ASM) data spanning 14 years. Starting from a recent study, indicating GX 13+1 as a possible dipping source candidate, we systematically searched for periodic dips in the X-ray light curves of GX 13+1 from 1996 up to 2013 using RXTE/ASM, and MAXI data to determine for the first time the X-ray orbital ephemeris of GX 13+1. We searched for a periodic signal in the ASM and MAXI light curves, finding a common periodicity of 24.53 d. We folded the 1.3-5 keV and 5-12.1 keV ASM light curves and the 2-4 and 4-10 keV MAXI light curves at the period of 24.53 d finding a periodic dip. To refine the value of the period we used the timing technique dividing the ASM light curve in eight intervals and the MAXI light curve in two intervals, obtaining four and two dip arrival times fr...

  15. Shallow Decay of X-ray Afterglows in Short GRBs: Energy Injection from a Millisecond Magnetar?

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    With the successful launch of Swift satellite, more and more data of early X-ray afterglows from short gamma-ray bursts have been collected. Some interesting features such as unusual afterglow light curves and unexpected X-ray flares are revealed. Especially, in some cases, there is a flat segment in the X-ray afterglow light curve. Here we present a simplified model in which we believe that the flattening part is due to energy injection from the central engine. We assume that this energy injection arises from the magnetic dipole radiation of a millisecond pulsar formed after the merger of two neutron stars. We check this model with the short GRB 060313. Our numerical results suggest that energy injection from a millisecond magnetar could make part of the X-ray afterglow light curve flat.

  16. Simultaneous X-ray and Ultraviolet spectroscopy of the Seyfert galaxy NGC 5548. III. X-ray time variability

    CERN Document Server

    Kaastra, J S; Crenshaw, D M; Krämer, S B; Arav, N; George, I M; Liedahl, D A; Van der Meer, R L J; Paerels, F B S; Turner, T J; Yaqoob, T

    2004-01-01

    The Seyfert 1 galaxy NGC 5548 was observed for a week by Chandra using both the HETGS and LETGS spectrometers. In this paper we study the time variability of the continuum radiation. During our observation, the source showed a gradual increase in flux over four days, followed by a rapid decrease and flattening of the light curve afterwards. Superimposed upon these relatively slow variations several short duration bursts or quasi-periodic oscillations occured with a typical duration of several hours and separation between 0.6-0.9 days. The bursts show a delay of the hard X-rays with respect to the soft X-rays of a few hours. We interprete these bursts as due to a rotating, fluctuating hot spot at approximately 10 gravitational radii; the time delay of the hard X-rays from the bursts agree with the canonical picture of Inverse Compton scattering of the soft accretion disk photons on a hot medium that is relatively close to the central black hole.

  17. High resolution x-ray Thomson scattering measurements from cryogenic hydrogen jets using the linac coherent light source

    Science.gov (United States)

    Fletcher, L. B.; Zastrau, U.; Galtier, E.; Gamboa, E. J.; Goede, S.; Schumaker, W.; Ravasio, A.; Gauthier, M.; MacDonald, M. J.; Chen, Z.; Granados, E.; Lee, H. J.; Fry, A.; Kim, J. B.; Roedel, C.; Mishra, R.; Pelka, A.; Kraus, D.; Barbrel, B.; Döppner, T.; Glenzer, S. H.

    2016-11-01

    We present the first spectrally resolved measurements of x-rays scattered from cryogenic hydrogen jets in the single photon counting limit. The 120 Hz capabilities of the LCLS, together with a novel hydrogen jet design [J. B. Kim et al., Rev. Sci. Instrum. (these proceedings)], allow for the ability to record a near background free spectrum. Such high-dynamic-range x-ray scattering measurements enable a platform to study ultra-fast, laser-driven, heating dynamics of hydrogen plasmas. This measurement has been achieved using two highly annealed pyrolytic graphite crystal spectrometers to spectrally resolve 5.5 keV x-rays elastically and inelastically scattered from cryogenic hydrogen and focused on Cornell-SLAC pixel array detectors [S. Herrmann et al., Nucl. Instrum. Methods Phys. Res., Sect. A 718, 550 (2013)].

  18. Light collection enhancement of the digital x-ray detector using Gd 2O 2S:Tb and CsI:Tl phosphors in the aspect of nano-scale light dispersions

    Science.gov (United States)

    Woo, Taeho; Kim, Taewoo

    2012-01-01

    The nano-scopic light collection is investigated for the Active Matrix Flat-Panel Imagers (AMFPIs). The simulations using two kinds of screens are shown for light collection of x-rays. Enhancement of the light collection is accomplished by the microlens system incorporated with x-ray detector. For digital radiographic and mammographic applications, indirect detection imagers use Gd 2O 2S:Tb or CsI:Tl scintillation screens to convert the x-ray into visible photons. The light collection efficiencies for Gd 2O 2S and CsI are obtained. In Gd 2O 2S, the 27 kVp and 82 μm are the highest light collection cases in both Lambertian and Isotropic geometries. In CsI, 20 keV and 150 μm case have the highest light collection efficiency. So, x-ray energy and scintillator thicknesses are considered as the optimized light collection. The optimum thickness and x-ray energy combination are used for the detector of this study. In this paper, it is concluded that the screens between 17 kVp and 25 kVp have higher light collections, which could be considered as the clinical purposes if it is necessary. This energy range is compared with other energy cases, which are examined in the study.

  19. Characterization of spatially resolved high resolution x-ray spectrometers for high energy density physics and light source experiments.

    Science.gov (United States)

    Hill, K W; Bitter, M; Delgado-Aparacio, L; Efthimion, P; Pablant, N A; Lu, J; Beiersdorfer, P; Chen, H; Magee, E

    2014-11-01

    A high resolution 1D imaging x-ray spectrometer concept comprising a spherically bent crystal and a 2D pixelated detector is being optimized for diagnostics of small sources such as high energy density physics (HEDP) and synchrotron radiation or x-ray free electron laser experiments. This instrument is used on tokamak experiments for Doppler measurements of ion temperature and plasma flow velocity profiles. Laboratory measurements demonstrate a resolving power, E/ΔE of order 10,000 and spatial resolution better than 10 μm. Initial tests of the high resolution instrument on HEDP plasmas are being performed.

  20. Probing the emission physics and weak/soft population of Gamma-Ray Bursts with LOFT. White Paper in Support of the Mission Concept of the Large Observatory for X-ray Timing

    DEFF Research Database (Denmark)

    Amati, L.; Stratta, G.; Atteia, J.L.

    of ultra- dense matter in neutron stars? Does matter orbiting close to the event horizon follow the predictions of general relativity? These goals are elaborated in the mission Yellow Book ( http://sci.esa.int/loft/ 53447-loft-yellow-book/ ) describing the LOFT mission as proposed in M3, which closely...... science case, but also for many other open questions in astrophysics. LOFT ’s primary instrument is the Large Area Detector (LAD), a 8 . 5 m 2 instrument operating in the 2–30 keV energy range, which will revolutionise studies of Galactic and extragalactic X-ray sources down to their fundamental time...... with an on-board alert system for the detection and rapid broadcasting to the ground of celestial bright and fast outbursts of X-rays (particularly, Gamma-ray Bursts). This paper is one of twelve White Papers that illustrate the unique potential of LOFT as an X-ray observatory in a variety of astrophysical...

  1. X-ray and visible light transmission as two-dimensional, full-field moisture-sensing techniques: A preliminary comparison

    Energy Technology Data Exchange (ETDEWEB)

    Tidwell, V.C.; Glass, R.J.

    1992-01-21

    Two independent high-resolution moisture-sensing techniques, x-ray absorption and light transmission, have been developed for use in two-dimensional, thin-slab experimental systems. The techniques yield full-field measurement capabilities with exceptional resolution of moisture content in time and space. These techniques represent powerful tools for the experimentalist to investigate processes governing unsaturated flow and transport through fractured and nonfractured porous media. Evaluation of these techniques has been accomplished by direct comparison of data obtained by means of the x-ray and light techniques as well as comparison with data collected by gravimetric and gamma-ray densitometry techniques. Results show excellent agreement between data collected by the four moisture-content measurement techniques. This program was established to support the Yucca Mountain Site Characterization Project.

  2. X-ray dose detector based on color changing of light-emitting polymer–metal complex hybrid material.

    OpenAIRE

    2012-01-01

    We report on the design, fabrication and performance of a poly (2-methoxy-5(2_-ethylhexyloxy)- p-phenylenevinylene)/tris-(8-hydroxyquinoline)aluminum (MEH-PPV/Alq3) X-ray dose detector for improving safety for cancer patients shortly before radiation therapy. The detector consists of an inexpen-sive (

  3. Abdominal x-ray

    Science.gov (United States)

    ... are, or may be, pregnant. Alternative Names Abdominal film; X-ray - abdomen; Flat plate; KUB x-ray ... Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also ...

  4. Extremity x-ray

    Science.gov (United States)

    ... degenerative) Bone tumor Broken bone (fracture) Dislocated bone Osteomyelitis (infection) Arthritis Other conditions for which the test ... Bone tumor Bone x-ray Broken bone Clubfoot Osteomyelitis X-ray Review Date 7/3/2016 Updated ...

  5. Centroiding and point response function measurements of the mirror/detector combination for the x-ray telescope on the SWIFT gamma-ray burst explorer

    Science.gov (United States)

    Ambrosi, Richard M.; Abbey, Anthony F.; Hutchinson, Ian; Willingale, Richard; Campana, Sergio; Cusumano, G.; Burkert, Wolfgang; Wells, Alan A.; Short, Alexander T.; Citterio, Oberto; Ghigo, Mauro; Tagliaferri, G.; Braeuninger, Heinrich W.

    2002-01-01

    The essential optical components of the Swift X-ray Telescope (XRT) are already developed items. They are: the flight spare x-ray mirror from the JET-X/Spectrum-X program and a MOS CCD (CCD22) of the type currently operating in orbit as part of the EPIC focal plane camera on the XMM- Newton. The JET-X mirrors were first calibrated at the Max Plank Institute for Extraterrestrial Physics' (MPE) Panter facility, Garching, Germany in 1996. Half energy widths (HEW) of 16 arc seconds at 1.5 keV were confirmed for the two flight mirrors and the flight spare. The calibration of the flight spare was repeated at Panter in July 2000 in order to establish whether any changes had occurred during the four years that the mirror had been in storage at the OAB, Milan, Italy. This results reported in this paper, confirm that the resolution of the JET-X mirrors has remained stable over this storage period. In an extension of this test program, the flight spare EPIC camera was installed at the focus of the JET-X mirror to simulate the optical system of the Swift X-ray telescope. On-axis and off-axis point spread functions (PSFs) were measured and calibration data sets were used to obtain centroid positions of X-ray point sources. The results confirmed Swift's ability to determine the centroid positions of sources at 100mCrab brightness to better than 1 arc second and provided a calibration of the centroiding process as a function of source flux and off axis angle. The presence of background events in the image frame introduced errors in the centroiding process, making the choice of centroiding algorithm important. Algorithm performance and the trade-off between processing speed and centroiding accuracy were investigated.

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

    Science.gov (United States)

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

    2017-02-01

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

  7. Self-attenuation artifacts and correction factors of light element measurements by X-ray analysis: Implication for mineral dust composition studies

    Science.gov (United States)

    Formenti, P.; Nava, S.; Prati, P.; Chevaillier, S.; Klaver, A.; Lafon, S.; Mazzei, F.; Calzolai, G.; Chiari, M.

    2010-01-01

    On a global scale, mineral dust is one of the major components of atmospheric aerosols and has important effects on the radiative budget of the atmosphere and thus on climate forcing. An accurate measurement of the concentration of crustal elements, namely Na, Mg, Al, Si, K, Ca, Ti, and Fe, is mandatory for the study of desert aerosols. The concentration of light elements, when measured by X-ray emission techniques such as X-ray fluorescence (XRF) and particle-induced X-ray emission (PIXE), can be underestimated owing to self-absorption of the emitted soft X-rays inside aerosol particles. In this work, we analyzed dust samples collected in field campaigns and samples produced in the laboratory using dust of known composition. Measurements have been conducted with PIXE and energy-dispersive XRF (ED-XRF), together with an attenuation-free technique such as particle-induced gamma-ray emission (PIGE) and attenuation corrected wavelength-dispersive XRF (WD-XRF) by internal standard calibration. We focus on the determination of Al and present results of a PIXE versus PIGE intercomparison. Aluminum concentration was measured with both techniques in dust samples collected by aircraft sampling over western Africa during winter 2006 and summer 2007. An underestimation of the Al concentration determined by PIXE was observed (up to 40%), and it was compared with the results of a simple calculation using basic physics and the size distribution of the collected aerosol. Similar attenuation was observed for Mg, Al, and Si in the laboratory samples analyzed by ED-XRF and WD-XRF. In order to use concentration ratios involving light elements as tracers of the region of emission of the sampled dust, these artifacts (i.e., underestimation of the concentration of light elements) induced by self-attenuation should be properly considered and corrected.

  8. Development and calibration of mirrors and gratings for the soft x-ray materials science beamline at the Linac Coherent Light Source free-electron laser.

    Science.gov (United States)

    Soufli, Regina; Fernández-Perea, Mónica; Baker, Sherry L; Robinson, Jeff C; Gullikson, Eric M; Heimann, Philip; Yashchuk, Valeriy V; McKinney, Wayne R; Schlotter, William F; Rowen, Michael

    2012-04-20

    This work discusses the development and calibration of the x-ray reflective and diffractive elements for the Soft X-ray Materials Science (SXR) beamline of the Linac Coherent Light Source (LCLS) free-electron laser (FEL), designed for operation in the 500 to 2000 eV region. The surface topography of three Si mirror substrates and two Si diffraction grating substrates was examined by atomic force microscopy (AFM) and optical profilometry. The figure of the mirror substrates was also verified via surface slope measurements with a long trace profiler. A boron carbide (B4C) coating especially optimized for the LCLS FEL conditions was deposited on all SXR mirrors and gratings. Coating thickness uniformity of 0.14 nm root mean square (rms) across clear apertures extending to 205 mm length was demonstrated for all elements, as required to preserve the coherent wavefront of the LCLS source. The reflective performance of the mirrors and the diffraction efficiency of the gratings were calibrated at beamline 6.3.2 at the Advanced Light Source synchrotron. To verify the integrity of the nanometer-scale grating structure, the grating topography was examined by AFM before and after coating. This is to our knowledge the first time B4C-coated diffraction gratings are demonstrated for operation in the soft x-ray region.

  9. X-Ray Supernovae

    CERN Document Server

    Immler, S; Immler, Stefan; Lewin, Walter H.G.

    2002-01-01

    We present a review of X-ray observations of supernovae (SNe). By observing the (~0.1--100 keV) X-ray emission from young SNe, physical key parameters such as the circumstellar matter (CSM) density, mass-loss rate of the progenitor and temperature of the outgoing and reverse shock can be derived as a function of time. Despite intensive search over the last ~25 years, only 15 SNe have been detected in X-rays. We review the individual X-ray observations of these SNe and discuss their implications as to our understanding of the physical processes giving rise to the X-ray emission.

  10. LOBSTER - New Space X-Ray telescopes

    Energy Technology Data Exchange (ETDEWEB)

    Hudec, R. [Astronomical Institute, Academy of Sciences of the Czech Republic, CZ-251 65 Ondrejov (Czech Republic); Pina, L. [Faculty of Nuclear Science, Czech Technical University, Prague (Czech Republic); Simon, V. [Astronomical Institute, Academy of Sciences of the Czech Republic, CZ-251 65 Ondrejov (Czech Republic); Sveda, L. [Faculty of Nuclear Science, Czech Technical University, Prague (Czech Republic); Inneman, A.; Semencova, V. [Center for Advanced X-ray Technologies, Reflex, Prague (Czech Republic); Skulinova, M. [Astronomical Institute, Academy of Sciences of the Czech Republic, CZ-251 65 Ondrejov (Czech Republic)

    2007-04-15

    We discuss the technological and scientific aspects of fully innovative very wide-field X-ray telescopes with high sensitivity. The prototypes of Lobster telescopes designed, developed and tested are very promising, allowing the proposals for space projects with very wide-field Lobster Eye X-ray optics to be considered for the first time. The novel telescopes will monitor the sky with unprecedented sensitivity and angular resolution of order of 1 arcmin. They are expected to contribute essentially to study of various astrophysical objects such as AGN, SNe, Gamma-ray bursts (GRBs), X-ray flashes (XRFs), galactic binary sources, stars, CVs, X-ray novae, various transient sources, etc. For example, the Lobster optics based X-ray All Sky Monitor is capable to detect around 20 GRBs and 8 XRFs yearly and this will surely significantly contribute to the related science.

  11. The response of silicon PNCCD sensors with aluminium on-chip filter to visible light, UV- and X-ray radiation

    Energy Technology Data Exchange (ETDEWEB)

    Granato, Stefanie

    2012-10-18

    There are various scientific applications, from astronomical observations to free electron lasers, that make use of X-ray semiconductor detectors like PNCCDs. The PNCCD is a pixelized semiconductor detector for simultaneous X-ray imaging and spectroscopy. For the seven PNCCD cameras of the eROSITA space telescope, a radiation entrance window including an on-chip optical blocking filter has been designed. The blocking filter is a necessity to minimize electron generation by visible light and UV radiation affecting X-ray spectroscopy. A PNCCD with such a blocking filter has not been used so far in astronomy. The following work deals with the analysis of the response of PNCCDs with on-chip filter. This includes the study of photon absorption and emission processes as well as the transport of electrons inside the detector entrance window. Furthermore it comprises the experimental characterization of the detector properties regarding the attenuation of light as well as their X-ray spectral redistribution function and quantum efficiency. With the ability to reveal the involved physical processes, the PNCCD is subject of analysis and measurement device at the same time. In addition to the results of the measurements, simulations of the solid state physics inside the detector are presented. A Geant4 Monte-Carlo code is extended by the treatment of charge loss in the entrance window and is verified by comparison with experimental data. Reproducing the chain of processes from photon absorption to charge collection, this work provides a detailed understanding of the formation of PNCCD spectra. The spectral features observed in the measurements are attributed to their point of origin inside the detector volume and explained by the model. The findings of this work allow high precision analysis of spectra of silicon detectors, e.g. of the eROSITA data, based on the presented detailed spectral response model.

  12. The X-ray light curve of the massive colliding wind Wolf-Rayet + O binary WR21a

    CERN Document Server

    Gosset, Eric

    2016-01-01

    Our dedicated XMM-Newton monitoring, as well as archival Chandra and Swift datasets, were used to examine the behaviour of the WN5h+O3V binary WR21a at high energies. For most of the orbit, the X-ray emission exhibits few variations. However, an increase in strength of the emission is seen before periastron, following a 1/D relative trend, where D is the separation between both components. This increase is rapidly followed by a decline due to strong absorption as the Wolf-Rayet (WR) comes in front. The fitted local absorption value appears to be coherent with a mass-loss rate of about 1x10^{-5} M_sol/yr for the WR component. However, absorption is not the only parameter affecting the X-ray emission at periastron as even the hard X-ray emission decreases, suggesting a possible collapse of the colliding wind region near to or onto the photosphere of the companion just before or at periastron. An eclipse may appear as another potential scenario, but it would be in apparent contradiction with several lines of evi...

  13. Minimum X-ray source size for a lamppost corona in light-bending models for AGN

    Science.gov (United States)

    Dovciak, M.; Done, C.

    2015-07-01

    The `lamppost' model is often used to describe the X-ray source geometry in AGN, where an infinitesimal point source is located on the black hole spin axis. This is especially invoked for Narrow Line Seyfert 1 galaxies, where an extremely broad iron line seen in episodes of low X-ray flux can be explained by extremely strong relativistic effects as the source approaches the black hole horizon. However, the source must also be large enough to intercept sufficient seed photons from the disc to make the hard X-ray Compton continuum which produces the observed iron line/reflected spectrum. This size scale also sets the minimum height of the corona in order that the source can fit above the event horizon. We calculate this using a fully relativistic ray tracing code, and apply to the most extreme NLS1, 1H0707-495. The inferred source size is too big for it to be at a height of less than one gravitational radius above the horizon.

  14. Minimum X-ray source size for a lamp-post corona in light-bending models for AGN

    CERN Document Server

    Dovciak, Michal

    2015-01-01

    The lamppost model is often used to describe the X-ray source geometry in AGN, where an infinitesimal point source is located on the black hole spin axis. This is especially invoked for Narrow Line Seyfert 1 (NLS1) galaxies, where an extremely broad iron line seen in episodes of low X-ray flux can both be explained by extremely strong relativistic effects as the source approaches the black hole horizon. The most extreme spectrum seen from the NLS1 1H0707-495 requires that the source is less than 1Rg above the event horizon in this geometry. However, the source must also be large enough to intercept sufficient seed photons from the disk to make the hard X-ray Compton continuum which produces the observed iron line/reflected spectrum. We use a fully relativistic ray tracing code to show that this implies that the source must be substantially larger than 1Rg in 1H0707-495 if the disk is the source of seed photons. Hence the source cannot fit as close as 1Rg to the horizon, so the observed spectrum and variabilit...

  15. Point spread function and centroiding accuracy measurements with the JET-X mirror and MOS CCD detector of the Swift gamma ray burst explorer's X-ray telescope

    Science.gov (United States)

    Ambrosi, R. M.; Abbey, A. F.; Hutchinson, I. B.; Willingale, R.; Wells, A.; Short, A. D. T.; Campana, S.; Citterio, O.; Tagliaferri, G.; Burkert, W.; Brauninger, H.

    2002-08-01

    The optical components of the Swift X-ray telescope (XRT) are already developed items. They are the flight spare X-ray mirror from the JET-X/Spectrum-X program and an MOS CCD (CCD22) of the type currently operating in orbit as part of the EPIC focal plane camera on XMM-Newton (SPIE 4140 (2000) 64). The JET-X mirrors were first calibrated at the Max Plank Institute for Extraterrestrial Physics' (MPE) Panter facility, Garching, Germany in 1996 (SPIE 2805 (1996) 56; SPIE 3114 (1997) 392). Half-energy widths of 16arcsec at 1.5keV were confirmed for the two flight mirrors and the flight spare. The calibration of the flight spare was repeated at Panter in July 2000 in order to establish whether any changes had occurred during the 4yr that the mirror had been in storage at the OAB, Milan, Italy. The results reported in this paper confirm that the resolution of the JET-X mirrors has remained stable over this storage period. In an extension of this test program, the flight spare EPIC camera was installed at the focus of the JET-X mirror to simulate the optical system of the Swift XRT. Tolerances in the mirror focal length, the on-axis and off-axis point spread functions were measured and calibration data sets were used to obtain centroid positions of X-ray point sources. The results confirmed Swift's ability to determine the centroid positions of sources at 100mCrab brightness to better than 1arcsec and provided a calibration of the centroiding process as a function of source flux and off-axis angle. The presence of background events in the image frame introduced errors in the centroiding process and this was accounted for by reducing the sampling area used for the centroiding algorithm.

  16. A CORRELATED STUDY OF OPTICAL AND X-RAY AFTERGLOWS OF GRBs

    Energy Technology Data Exchange (ETDEWEB)

    Li, Liang; Ryde, Felix [Department of Physics, KTH Royal Institute of Technology, SE-106 91 Stockholm (Sweden); Wu, Xue-Feng [Chinese Center for Antarctic Astronomy, Chinese Academy of Sciences, Nanjing 210008 (China); Huang, Yong-Feng; Tang, Qing-Wen; Geng, Jin-Jun [Department of Astronomy, Nanjing University, Nanjing 210093, Jiangsu (China); Wang, Xiang-Gao; Liang, En-Wei [GXU-NAOC Center for Astrophysics and Space Sciences, Department of Physics, Guangxi University, Nanjing 530004 (China); Liang, Yun-Feng [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Zhang, Bin-Bin [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Wang, Yu [Dip. di Fisica and ICRA, Sapienza Universit di Roma, Piazzale Aldo Moro 5, I-00185 Rome (Italy); Wei, Jian-Yan [National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012 (China); Zhang, Bing, E-mail: fryde@kth.se, E-mail: liang.li@fysik.su.se [Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154 (United States)

    2015-05-20

    We study an extensive sample of 87 gamma-ray bursts (GRBs) for which there are well-sampled and simultaneous optical and X-ray light curves. We extract the cleanest possible signal of the afterglow component and compare the temporal behaviors of the X-ray light curve, observed by Swift XRT, and optical data, observed by UVOT and ground-based telescopes for each individual burst. Overall we find that 62% of the GRBs are consistent with the standard afterglow model. When more advanced modeling is invoked, up to 91% of the bursts in our sample may be consistent with the external-shock model. A large fraction of these bursts are consistent with occurring in a constant interstellar density medium (61%) while only 39% of them occur in a wind-like medium. Only nine cases have afterglow light curves that exactly match the standard fireball model prediction, having a single power-law decay in both energy bands that are observed during their entire duration. In particular, for the bursts with chromatic behavior, additional model assumptions must be made over limited segments of the light curves in order for these bursts to fully agree with the external-shock model. Interestingly, for 54% of the X-ray and 40% of the optical band observations, the end of the shallow decay (t{sup ∼−0.5}) period coincides with the jet-break (t{sup ∼−p}) time, causing an abrupt change in decay slope. The fraction of the burst that is consistent with the external-shock model is independent of the observational epochs in the rest frame of GRBs. Moreover, no cases can be explained by the cooling frequency crossing the X-ray or optical band.

  17. Cryogenic coherent X-ray diffraction imaging of biological samples at SACLA: a correlative approach with cryo-electron and light microscopy.

    Science.gov (United States)

    Takayama, Yuki; Yonekura, Koji

    2016-03-01

    Coherent X-ray diffraction imaging at cryogenic temperature (cryo-CXDI) allows the analysis of internal structures of unstained, non-crystalline, whole biological samples in micrometre to sub-micrometre dimensions. Targets include cells and cell organelles. This approach involves preparing frozen-hydrated samples under controlled humidity, transferring the samples to a cryo-stage inside a vacuum chamber of a diffractometer, and then exposing the samples to coherent X-rays. Since 2012, cryo-coherent diffraction imaging (CDI) experiments have been carried out with the X-ray free-electron laser (XFEL) at the SPring-8 Ångstrom Compact free-electron LAser (SACLA) facility in Japan. Complementary use of cryo-electron microscopy and/or light microscopy is highly beneficial for both pre-checking samples and studying the integrity or nature of the sample. This article reports the authors' experience in cryo-XFEL-CDI of biological cells and organelles at SACLA, and describes an attempt towards reliable and higher-resolution reconstructions, including signal enhancement with strong scatterers and Patterson-search phasing.

  18. X-ray counterpart of gravitational waves due to binary neutron star mergers: light curves, luminosity functions, and event rate densities

    CERN Document Server

    Sun, Hui; Gao, He

    2016-01-01

    Zhang (2013) proposed a type of GRB-less X-ray transient associated with double neutron star (NS-NS) mergers under the conjecture of a rapidly-spinning magnetar merger product with the line of sight off the short GRB beam. We investigate possible light curves of these transients by considering different observer's viewing angles, including looking into a free zone where the emission due to direct dissipation of the magnetar wind is observable, and a trapped zone where X-rays are initially trapped by the ejecta launched during the merger, but later become transparent when the ejecta become optically thin. We perform Monte Carlo simulations to calculate the peak luminosity function (LF) and event rate density of these X-ray transients. By considering that a fraction of massive neutron stars may be supra-massive and collapse into black holes after a certain time, we investigate how the predicted luminosity functions depend on the equation of state (EoS) of the central object. In general, the luminosity functions...

  19. 1SXPS: A Deep Swift X-Ray Telescope Point Source Catalog with Light Curves and Spectra

    Science.gov (United States)

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

    2013-01-01

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

  20. LIGHT SOURCE: Optics for the lattice of the compact storage ring for a Compton X-ray source

    Science.gov (United States)

    Yu, Pei-Cheng; Wang, Yu; Shen, Xiao-Zhe; Huang, Wen-Hui; Yan, Li-Xin; Du, Ying-Chao; Li, Ren-Kai; Tang, Chuan-Xiang

    2009-06-01

    We present two types of optics for the lattice of a compact storage ring for a Compton X-ray source. The optics design for different operation modes of the storage ring are discussed in detail. For the pulse mode optics, an IBS-suppression scheme is applied to optimize the optics for lower IBS emittance growth rate; as for the steady mode, the method to control momentum compact factor is adopted [Gladkikh P, Phys. Rev. ST Accel. Beams 8, 050702] to obtain stability of the electron beam.

  1. X-Ray Polarimetry

    CERN Document Server

    Kaaret, Philip

    2014-01-01

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

  2. 1SXPS: A deep Swift X-ray Telescope point source catalog with light curves and spectra

    CERN Document Server

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

    2013-01-01

    We present the 1SXPS (Swift-XRT Point Source) catalog of 151,524 X-ray point-sources detected by the Swift-XRT in 8 years of operation. The catalog covers 1905 square degrees distributed approximately uniformly on the sky. We analyze the data in two ways. First we consider all observations individually, for which we have a typical sensitivity of ~3e-13 erg/cm2/s (0.3--10 keV). Then we co-add all data covering the same location on the sky: these images have a typical sensitivity of ~9e-14 erg/cm2/s (0.3--10 keV). Our sky coverage is nearly 2.5 times that of 3XMM-DR4, although the catalog is a factor of ~1.5 less sensitive. The median position error is 5.5" (90% confidence), including systematics. Our source detection method improves on that used in previous XRT catalogs and we report >68,000 new X-ray sources. The goals and observing strategy of the Swift satellite allow us to probe source variability on multiple timescales, and we find ~30,000 variable objects in our catalog. For every source we give position...

  3. Molecular weight–gyration radius relation of globular proteins: a comparison of light scattering, small-angle X-ray scattering and structure-based data

    Science.gov (United States)

    Smilgies, Detlef-M.; Folta-Stogniew, Ewa

    2015-01-01

    The molecular weight–gyration radius relation for a number of globular proteins based on experimental light scattering data is compared with small-angle X-ray scattering data recently published by Mylonas & Svergun [J. Appl. Cryst. (2007 ▸), 40, s245–s249]. In addition, other recent experimental data and theoretical calculations are reviewed. It is found that the M W–R g relation for the globular proteins is well represented by a power law with an exponent of 0.37 (2). PMID:26500468

  4. The Swift/BAT Hard X-ray Transient Monitor

    CERN Document Server

    Krimm, Hans A; Corbet, Robin H D; Perlman, Aaron B; Romano, Patrizia; Kennea, Jamie A; Bloom, Joshua S; Barthelmy, Scott D; Baumgartner, Wayne H; Cummings, James R; Gehrels, Neil; Lien, Amy Y; Markwardt, Craig B; Palmer, David M; Sakamoto, Taka; Stamatikos, Michael; Ukwatta, Tilan N

    2013-01-01

    The Swift/Burst Alert Telescope (BAT) hard X-ray transient monitor provides near real-time coverage of the X-ray sky in the energy range 15-50 keV. The BAT observes 88% of the sky each day with a detection sensitivity of 5.3 mCrab for a full-day observation and a time resolution as fine as 64 seconds. The three main purposes of the monitor are (1) the discovery of new transient X-ray sources, (2) the detection of outbursts or other changes in the flux of known X-ray sources, and (3) the generation of light curves of more than 900 sources spanning over eight years. The primary interface for the BAT transient monitor is a public web page. Between 2005 February 12 and 2013 April 30, 245 sources have been detected in the monitor, 146 of them persistent and 99 detected only in outburst. Among these sources, 17 were previously unknown and were discovered in the transient monitor. In this paper, we discuss the methodology and the data processing and filtering for the BAT transient monitor and review its sensitivity ...

  5. New lanthanide complexes for sensitized visible and near-IR light emission: synthesis, 1H NMR, and X-ray structural investigation and photophysical properties.

    Science.gov (United States)

    Quici, Silvio; Marzanni, Giovanni; Forni, Alessandra; Accorsi, Gianluca; Barigelletti, Francesco

    2004-02-23

    We describe the syntheses, the 1H NMR studies in CD3OD and D2O as solvent, the X-ray characterization, and the luminescence properties in D2O solution of the two complexes Eu.1 and Er.1, where 1 is a dipartite ligand that includes (i) a 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A) unit serving as hosting site for the metal center; and (ii) a phenanthroline unit which plays the role of light antenna for the sensitization process of the metal centered luminescence. In a previous report (Inorg. Chem. 2002, 41, 2777), we have shown that for Eu.1 there are no water molecules within the first coordination sphere. X-ray and 1H NMR results reported here are consistent with full saturation of the nine coordination sites within the Eu.1 and Er.1 complexes. In addition, these studies provide important details regarding the conformations, square antiprism (SAP) and twisted square antiprism (TSAP), adopted in solution by these complexes. The luminescence results are consistent with both an effective intersystem crossing (ISC) at the light absorbing phenanthroline unit (lambda(exc) = 278 nm) and an effective energy transfer (en) process from the phenanthroline donor to the cation acceptor (with unit or close to unit efficiency for both steps). In D2O solvent, the overall sensitization efficiency, phi(se), is 0.3 and 5 x 10(-6), for Eu.1 (main luminescence peaks at 585, 612, 699 nm) and Er.1 (luminescence peak at 1530 nm), respectively. The photophysical properties of both complexes are discussed with reference to their structural features as elucidated by the obtained 1H NMR and X-ray results.

  6. Dental x-rays

    Science.gov (United States)

    ... X-rays are a form of high energy electromagnetic radiation. The x-rays penetrate the body to form ... for detecting cavities, unless the decay is very advanced and deep. Many ... The amount of radiation given off during the procedure is less than ...

  7. Visualizing Cell Architecture and Molecular Location Using Soft X-Ray Tomography and Correlated Cryo-Light Microscopy

    Science.gov (United States)

    McDermott, Gerry; Le Gros, Mark A.; Larabell, Carolyn A.

    2012-05-01

    Living cells are structured to create a range of microenvironments that support specific chemical reactions and processes. Understanding how cells function therefore requires detailed knowledge of both the subcellular architecture and the location of specific molecules within this framework. Here we review the development of two correlated cellular imaging techniques that fulfill this need. Cells are first imaged using cryogenic fluorescence microscopy to determine the location of molecules of interest that have been labeled with fluorescent tags. The same specimen is then imaged using soft X-ray tomography to generate a high-contrast, 3D reconstruction of the cells. Data from the two modalities are then combined to produce a composite, information-rich view of the cell. This correlated imaging approach can be applied across the spectrum of problems encountered in cell biology, from basic research to biotechnological and biomedical applications such as the optimization of biofuels and the development of new pharmaceuticals.

  8. LIGHT SOURCE: RF deflecting cavity for bunch length measurement in Tsinghua Thomson scattering X-ray source

    Science.gov (United States)

    Shi, Jia-Ru; Chen, Huai-Bi; Tang, Chuan-Xiang; Huang, Wen-Hui; Du, Ying-Chao; Zheng, Shu-Xin; Ren, Li

    2009-06-01

    An RF deflecting cavity used for bunch length measurement has been designed and fabricated at Tsinghua University for the Thomson Scattering X-Ray Source. The cavity is a 2856 MHz, π-mode, 3-cell standing-wave cavity, to diagnose the 3.5 MeV beam produced by photocathode electron gun. With a larger power source, the same cavity will again be used to measure the accelerated beam with energy of 50 MeV before colliding with the laser pulse. The RF design using MAFIA for both the cavity shape and the power coupler is reviewed, followed by presenting the fabrication procedure and bench measurement results of two cavities.

  9. X-ray imaging by partially coherent synchrotron light. Application to metallic alloys, tooth dentin and natural rock

    Energy Technology Data Exchange (ETDEWEB)

    Zabler, Simon Andreas

    2007-10-09

    The hard spectrum which is available on the BAMline at Berlin's synchrotron BESSY offers the rare opportunity to perform high-resolution X-ray imaging experiments with a partially coherent beam. This thesis work reports on the development of a new tomography system, including Fresnel-propagated imaging, and its application to three specific materials science problems from the fields of engineering materials, biology and earth science. Static and dynamic 2D and 3D images were recorded from a variety of aluminum-based alloys. Coarsening of particle agglomerates (at high solid volume fraction) in liquid solution, as well as rheological properties of semi-solid alloys are thus characterized. Dentin is characterized by a quasi-parallel arrangement of micrometer-sized tubules. This work shows how high-resolution 3D images of water-immersed tooth dentin are recorded, and detailed simulations of the optical wave propagation reveal that Fresnel-images contain additional information about the dense cuff of peritubular dentin surrounding the tubules. The cuff thickness can be extrapolated from the interference fringes that form the propagated images of tubules. Absorption and Fresnel-propagated X-ray tomography are applied to measure samples of different rocks before and after mechanical compression nondestructively. In a first approach, limestone and greywacke are investigated, representing two sedimentary rocks of different grain size. Basalt and granite are tested in a second approach to compare different rock types. Development of cracks is observed in all materials, leading to fracture when increasing mechanical load is applied. In this work, relatively small mm-sized samples are used in order to test a classical fracture model wherein micro-flaws initiate the formation of larger cracks. For the first time, Fresnel-propagated imaging is applied to rock samples, highlighting micrometer-sized intergranular porosity as well as different material phases. The latter is

  10. X-Ray-powered Macronovae

    Science.gov (United States)

    Kisaka, Shota; Ioka, Kunihito; Nakar, Ehud

    2016-02-01

    A macronova (or kilonova) was observed as an infrared excess several days after the short gamma-ray burst GRB 130603B. Although the r-process radioactivity is widely discussed as an energy source, it requires a huge mass of ejecta from a neutron star (NS) binary merger. We propose a new model in which the X-ray excess gives rise to the simultaneously observed infrared excess via thermal re-emission, and explore what constraints this would place on the mass and velocity of the ejecta. This X-ray-powered model explains both the X-ray and infrared excesses with a single energy source such as the central engine like a black hole, and allows for a broader parameter region than the previous models, in particular a smaller ejecta mass ˜ {10}-3{--}{10}-2{M}⊙ and higher iron abundance mixed as suggested by general relativistic simulations for typical NS-NS mergers. We also discuss the other macronova candidates in GRB 060614 and GRB 080503, and the implications for the search of electromagnetic counterparts to gravitational waves.

  11. X-Ray Surveys

    CERN Document Server

    Giommi, P; Perri, M

    1998-01-01

    A review of recent developments in the field of X-ray surveys, especially in the hard (2-10 and 5-10 keV) bands, is given. A new detailed comparison between the measurements in the hard band and extrapolations from ROSAT counts, that takes into proper account the observed distribution of spectral slopes, is presented. Direct comparisons between deep ROSAT and BeppoSAX images show that most hard X-ray sources are also detected at soft X-ray energies. This may indicate that heavily cutoff sources, that should not be detectable in the ROSAT band but are expected in large numbers from unified AGN schemes, are in fact detected because of the emerging of either non-nuclear components, or of reflected, or partially transmitted nuclear X-rays. These soft components may complicate the estimation of the soft X-ray luminosity function and cosmological evolution of AGN.

  12. In Depth Analyses of LEDs by a Combination of X-ray Computed Tomography (CT) and Light Microscopy (LM) Correlated with Scanning Electron Microscopy (SEM).

    Science.gov (United States)

    Meyer, Jörg; Thomas, Christian; Tappe, Frank; Ogbazghi, Tekie

    2016-06-16

    In failure analysis, device characterization and reverse engineering of light emitting diodes (LEDs), and similar electronic components of micro-characterization, plays an important role. Commonly, different techniques like X-ray computed tomography (CT), light microscopy (LM) and scanning electron microscopy (SEM) are used separately. Similarly, the results have to be treated for each technique independently. Here a comprehensive study is shown which demonstrates the potentials leveraged by linking CT, LM and SEM. In depth characterization is performed on a white emitting LED, which can be operated throughout all characterization steps. Major advantages are: planned preparation of defined cross sections, correlation of optical properties to structural and compositional information, as well as reliable identification of different functional regions. This results from the breadth of information available from identical regions of interest (ROIs): polarization contrast, bright and dark-field LM images, as well as optical images of the LED cross section in operation. This is supplemented by SEM imaging techniques and micro-analysis using energy dispersive X-ray spectroscopy.

  13. 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.

    2010-01-01

    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

  14. High Energy Vision: Processing X-rays

    CERN Document Server

    DePasquale, Joseph; Edmonds, Peter

    2015-01-01

    Astronomy is by nature a visual science. The high quality imagery produced by the world's observatories can be a key to effectively engaging with the public and helping to inspire the next generation of scientists. Creating compelling astronomical imagery can, however, be particularly challenging in the non-optical wavelength regimes. In the case of X-ray astronomy, where the amount of light available to create an image is severely limited, it is necessary to employ sophisticated image processing algorithms to translate light beyond human vision into imagery that is aesthetically pleasing while still being scientifically accurate. This paper provides a brief overview of the history of X-ray astronomy leading to the deployment of NASA's Chandra X-ray Observatory, followed by an examination of the specific challenges posed by processing X-ray imagery. The authors then explore image processing techniques used to mitigate such processing challenges in order to create effective public imagery for X-ray astronomy. ...

  15. Novel X-ray telescopes for wide-field X-ray monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Hudec, R. [Academy of science of Czech Republic, Ondrejov (Czech Republic); Inneman, A. [Centre for advanced X-ray technologies Reflex sro, Prague (Czech Republic); Pina, L.; Sveda, L. [Czech Technical Univ., Prague (Czech Republic). Faculty of Nuclear Science

    2005-07-15

    We report on fully innovative very wide-field of view X-ray telescopes with high sensitivity as well as large field of view. The prototypes are very promising, allowing the proposals for space projects with very wide-field Lobster-eye X-ray optics to be considered. The novel telescopes will monitor the sky with unprecedented sensitivity and angular resolution of order of 1 arcmin. They are expected to contribute essentially to study and to understand various astrophysical objects such as AGN, SNe, Gamma-ray bursts (GRBs), X-ray flashes (XRFs), galactic binary sources, stars, CVs, X-ray novae, various transient sources, etc. The Lobster optics based X-ray All Sky Monitor is capable to detect around 20 GRBs and 8 XRFs yearly and this will surely significantly contribute to the related science.

  16. Nanosecond x-ray Laue diffraction apparatus suitable for laser shock compression experiments.

    Science.gov (United States)

    Suggit, Matthew; Kimminau, Giles; Hawreliak, James; Remington, Bruce; Park, Nigel; Wark, Justin

    2010-08-01

    We have used nanosecond bursts of x-rays emitted from a laser-produced plasma, comprised of a mixture of mid-Z elements, to produce a quasiwhite-light spectrum suitable for performing Laue diffraction from single crystals. The laser-produced plasma emits x-rays ranging in energy from 3 to in excess of 10 keV, and is sufficiently bright for single shot nanosecond diffraction patterns to be recorded. The geometry is suitable for the study of laser-shocked crystals, and single-shot diffraction patterns from both unshocked and shocked silicon crystals are presented.

  17. Ultra-precision fabrication of 500 mm long and laterally graded Ru/C multilayer mirrors for X-ray light sources.

    Science.gov (United States)

    Störmer, M; Gabrisch, H; Horstmann, C; Heidorn, U; Hertlein, F; Wiesmann, J; Siewert, F; Rack, A

    2016-05-01

    X-ray mirrors are needed for beam shaping and monochromatization at advanced research light sources, for instance, free-electron lasers and synchrotron sources. Such mirrors consist of a substrate and a coating. The shape accuracy of the substrate and the layer precision of the coating are the crucial parameters that determine the beam properties required for various applications. In principal, the selection of the layer materials determines the mirror reflectivity. A single layer mirror offers high reflectivity in the range of total external reflection, whereas the reflectivity is reduced considerably above the critical angle. A periodic multilayer can enhance the reflectivity at higher angles due to Bragg reflection. Here, the selection of a suitable combination of layer materials is essential to achieve a high flux at distinct photon energies, which is often required for applications such as microtomography, diffraction, or protein crystallography. This contribution presents the current development of a Ru/C multilayer mirror prepared by magnetron sputtering with a sputtering facility that was designed in-house at the Helmholtz-Zentrum Geesthacht. The deposition conditions were optimized in order to achieve ultra-high precision and high flux in future mirrors. Input for the improved deposition parameters came from investigations by transmission electron microscopy. The X-ray optical properties were investigated by means of X-ray reflectometry using Cu- and Mo-radiation. The change of the multilayer d-spacing over the mirror dimensions and the variation of the Bragg angles were determined. The results demonstrate the ability to precisely control the variation in thickness over the whole mirror length of 500 mm thus achieving picometer-precision in the meter-range.

  18. Microfocussing of synchrotron X-rays using X-ray refractive lens developed at Indus-2 deep X-ray lithography beamline

    Indian Academy of Sciences (India)

    V P Dhamgaye; M K Tiwari; K J S Sawhney; G S Lodha

    2014-07-01

    X-ray lenses are fabricated in polymethyl methacrylate using deep X-ray lithography beamline of Indus-2. The focussing performance of these lenses is evaluated using Indus-2 and Diamond Light Source Ltd. The process steps for the fabrication of X-ray lenses and microfocussing at 10 keV at moderate and low emittance sources are compared.

  19. X-ray spectral properties of accretion discs in X-ray binaries

    Energy Technology Data Exchange (ETDEWEB)

    White, N.E.; Stella, L.; Parmar, A.N.

    1988-01-01

    Exosat observations are used to compare the spectral properties of the persistent emission from a number of X-ray burst sources, high-luminosity low-mass X-ray binaries (LMXRB) and galactic black hole candidates with various models for X-ray emission from an accretion disk surrounding a compact object in a binary system. It is shown that only a Comptonization model provides a good fit to all of the spectra considered. The fits to the spectra of the high-luminosity LMXRB systems necessitate an additional blackbody component with a luminosity 16 to 34 percent that from the Comptonized component. 82 references.

  20. X-ray lasers

    CERN Document Server

    Elton, Raymond C

    2012-01-01

    The first in its field, this book is both an introduction to x-ray lasers and a how-to guide for specialists. It provides new entrants and others interested in the field with a comprehensive overview and describes useful examples of analysis and experiments as background and guidance for researchers undertaking new laser designs. In one succinct volume, X-Ray Lasers collects the knowledge and experience gained in two decades of x-ray laser development and conveys the exciting challenges and possibilities still to come._Add on for longer version of blurb_M>The reader is first introduced

  1. Accelerator-driven X-ray Sources

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Dinh Cong [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-09

    After an introduction which mentions x-ray tubes and storage rings and gives a brief review of special relativity, the subject is treated under the following topics and subtopics: synchrotron radiation (bending magnet radiation, wiggler radiation, undulator radiation, brightness and brilliance definition, synchrotron radiation facilities), x-ray free-electron lasers (linac-driven X-ray FEL, FEL interactions, self-amplified spontaneous emission (SASE), SASE self-seeding, fourth-generation light source facilities), and other X-ray sources (energy recovery linacs, Inverse Compton scattering, laser wakefield accelerator driven X-ray sources. In summary, accelerator-based light sources cover the entire electromagnetic spectrum. Synchrotron radiation (bending magnet, wiggler and undulator radiation) has unique properties that can be tailored to the users’ needs: bending magnet and wiggler radiation is broadband, undulator radiation has narrow spectral lines. X-ray FELs are the brightest coherent X-ray sources with high photon flux, femtosecond pulses, full transverse coherence, partial temporal coherence (SASE), and narrow spectral lines with seeding techniques. New developments in electron accelerators and radiation production can potentially lead to more compact sources of coherent X-rays.

  2. The internal structure of Early Cambrian fossil embryo Olivooides revealed in the light of Synchrotron X-ray Tomographic Microscopy

    Institute of Scientific and Technical Information of China (English)

    CHEN Fang; DONG XiPing

    2008-01-01

    Countless fossil embryo Olivooides and the hatched larvae, juveniles and adults (the latter two kinds are Punctatus) are recovered by means of acid maceration from the fine-crystalline to medium-crystalline phosphatic limestone and phosphatic micrite of Early Cambrian Kuanchuanpu Formation at the Shizhonggou section, near Kuanchuanpu Village, Ningqiang County, Shaanxi Province, China. Using the technique of Synchrotron X-ray Tomographic Microscopy, the 3D internal structure of Olivooides and Punctatus is reconstructed. The morphological and statistic analyses are also given to the stellae structure of Olivooides and Punctatus, which indicates that this structure is a result of adaptive evolution to a lifestyle of fast-attaching after hatching, probably with the function of mucilage secretion. The internal structure of Punctatus is described and discussed. The ovum-like structure, a common internal feature of Punctatus, is considered as the taphonomic structure, rather than eggs or other biological structure. This structure is thought to be formed after the burial of the animal and before or during the mineralization. The original internal structure of Punctatus is assumed to be tabulae-filled, with soft body grown on them.

  3. Hard X-ray Spectral Investigations of Gamma-ray Bursts, 120521C and 130606A, at High-redshift z~6

    CERN Document Server

    Yasuda, Tetsuya; Enomoto, Junich; Tashiro, Makoto S

    2016-01-01

    This study presents the temporal and spectral analysis of the prompt emission of two high-redshift gamma-ray bursts (GRBs), 120521C at $z\\sim6$ and 130606A at $z\\sim5.91$, which were performed using the Swift-XRT/BAT and the Suzaku-WAM simultaneously. Based on follow-up XRT observations, the longest durations of the prompt emissions were approximately $80$ s (120521C) and $360$ s (130606A) in the rest frame of each GRB, which are categorized as long-duration GRBs, but are insufficiently long compared with the predicted duration of GRBs that originate from first-generation stars. Because of the wide bandpass of the instruments covering the ranges of 15 keV--5 MeV (BAT-WAM) and 0.3 keV--5.0 MeV (XRT-BAT-WAM), we successfully determined the $\

  4. Investigation of magnetically smart films applied to correct the surface profile of light weight X-ray optics in two directions

    Science.gov (United States)

    Wang, Xiaoli; Yao, Youwei; Cao, Jian; Vaynman, Semyon; Graham, Michael E.; Liu, Tianchen; Ulmer, M. P.

    2015-09-01

    Our goal is to improve initially fabricated X-ray optics figures by applying a magnetic field to drive a magnetic smart material (MSM) coating on the non-reflecting side of the mirror. The consequent deformation of the surface should be three-dimensional. Here we will report on the results of working with a glass sample of 50x50x0.2 mm that has been coated with MSMs. The coated glass can be deformed in 3 dimensions and its surface profile was measured under our Zygo NewView white light interferometer (WLI). The driving magnetic field was produced via a pseudo-magnetic write head made up of two permanent magnet posts. The magnet posts were moved about the bottom of the glass sample with a 3-d computer controlled translation stage. The system allowed four degrees of freedom of motion, i.e., up and down, side to side, back and forth, and rotation of the posts (3.175 mm diameter) about the vertical axis to allow us to change the orientation of the magnetic field in the (horizontal) plane of the sample. We established a finite element analysis (FEA) model to predict deformations and compare with the observed results in order to guide the application of the magnetically controlled MSMs to improve the future X-ray optics figures.

  5. X-Ray Diffraction.

    Science.gov (United States)

    Smith, D. K.; Smith, K. L.

    1980-01-01

    Reviews applications in research and analytical characterization of compounds and materials in the field of X-ray diffraction, emphasizing new developments in applications and instrumentation in both single crystal and powder diffraction. Cites 414 references. (CS)

  6. Pelvis x-ray

    Science.gov (United States)

    X-ray - pelvis ... Tumors Degenerative conditions of bones in the hips, pelvis, and upper legs ... hip joint Tumors of the bones of the pelvis Sacroiliitis (inflammation of the area where the sacrum ...

  7. X-ray - skeleton

    Science.gov (United States)

    ... x-ray particles pass through the body. A computer or special film records the images. Structures that ... M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health ...

  8. Bone x-ray

    Science.gov (United States)

    ... or broken bone Bone tumors Degenerative bone conditions Osteomyelitis (inflammation of the bone caused by an infection) ... Multiple myeloma Osgood-Schlatter disease Osteogenesis imperfecta Osteomalacia Osteomyelitis Paget disease of the bone Rickets X-ray ...

  9. Hand x-ray

    Science.gov (United States)

    ... include fractures, bone tumors , degenerative bone conditions, and osteomyelitis (inflammation of the bone caused by an infection). ... chap 46. Read More Bone tumor Broken bone Osteomyelitis X-ray Review Date 9/8/2014 Updated ...

  10. Chest X-Ray

    Medline Plus

    Full Text Available ... breath, persistent cough, fever, chest pain or injury. It may also be useful to help diagnose and ... have some concerns about chest x-rays. However, it’s important to consider the likelihood of benefit to ...

  11. Tuberculosis, advanced - chest x-rays (image)

    Science.gov (United States)

    Tuberculosis is an infectious disease that causes inflammation, the formation of tubercules and other growths within tissue, ... death. These chest x-rays show advanced pulmonary tuberculosis. There are multiple light areas (opacities) of varying ...

  12. 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 ...

  13. 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 ...

  14. Decay phases of Swift X-ray afterglows and the forward-shock model.

    Science.gov (United States)

    Panaitescu, A

    2007-05-15

    The X-ray flux of the gamma-ray burst (GRB) afterglows monitored by the Swift satellite from January 2005 to July 2006 displays one to four phases of flux power-law decay. In chronological order, they are: the GRB tail, the 'hump', the standard decay and the post-jet-break decay. More than half of the GRB tails can be identified with the large-angle emission produced during the burst (but arriving later at observer). The remaining, slower GRB tails imply that the gamma-ray mechanism continues to radiate after the burst, as also suggested by the frequent occurrence of X-ray flares during the burst tail. The several GRB tails exhibiting a slow unbroken power-law decay until 100ks must be attributed to the forward shock. In fact, the decay of most GRB tails is also consistent with that of the forward-shock emission from a narrow jet. The X-ray light-curve hump may be due to an increase of the kinetic energy per solid angle of the forward-shock region visible to the observer, caused by either the transfer of energy from ejecta to the forward shock or the emergence of the emission from an outflow seen from a location outside the jet opening. The decay following the X-ray light-curve hump is consistent with the emission from an adiabatic blast wave but, contrary to expectations, the light-curve decay index and spectral slope during this phase are not correlated. The X-ray light curves of two dozens X-ray afterglows that followed for more than a week do not exhibit a jet break, in contrast with the behaviour of pre-Swift optical afterglows, which displayed jet breaks at 0.5-2 days. Nevertheless, the X-ray light curves of several Swift afterglows show a second steepening break at 0.4-3 days that is consistent with the break expected for a jet when its edge becomes visible to the observer.

  15. X-ray enhancement and long-term evolution of swift J1822.3–1606

    Energy Technology Data Exchange (ETDEWEB)

    Benli, Onur; Çalışkan, Ş.; Ertan, Ü.; Alpar, M. A. [Sabancı University, Orhanlı-Tuzla, İstanbul 34956 (Turkey); Trümper, J. E. [Max-Planck-Institut für extraterrestrische Physik, Geissenbachstrasse, 85740 Garching bei München (Germany); Kylafis, N. D., E-mail: onurbenli@sabanciuniv.edu [Physics Department and Institute of Theoretical and Computational Physics, University of Crete, 71003 Heraklion, Crete (Greece)

    2013-12-01

    We investigate the X-ray enhancement and the long-term evolution of the recently discovered second 'low-B magnetar' Swift J1822.3-1606 in the frame of the fallback disk model. During a soft gamma burst episode, the inner disk matter is pushed back to larger radii, forming a density gradient at the inner disk. Subsequent relaxation of the inner disk could account for the observed X-ray enhancement light curve of Swift J1822.3-1606. We obtain model fits to the X-ray data with basic disk parameters similar to those employed to explain the X-ray outburst light curves of other anomalous X-ray pulsars and soft gamma repeaters. The long period (8.4 s) of the neutron star can be reached by the effect of the disk torques in the long-term accretion phase ((1-3) × 10{sup 5} yr). The currently ongoing X-ray enhancement could be due to a transient accretion epoch, or the source could still be in the accretion phase in quiescence. Considering these different possibilities, we determine the model curves that could represent the long-term rotational and the X-ray luminosity evolution of Swift J1822.3-1606, which constrain the strength of the magnetic dipole field to the range of (1-2) × 10{sup 12} G on the surface of the neutron star.

  16. Measurement of coherence length and incoherent source size of hard x-ray undulator beamline at Pohang Light Source-II

    Energy Technology Data Exchange (ETDEWEB)

    Park, So Yeong; Hong, Chung Ki [Department of Physics, POSTECH, Pohang 790-784 (Korea, Republic of); Lim, Jun, E-mail: limjun@postech.ac.kr [Pohang Accelerator Laboratory, POSTECH, Pohang 790-784 (Korea, Republic of)

    2014-04-15

    We measured the spatial coherence length and incoherent source size of a hard x-ray undulator beamline at Pohang Light Source-II, the stored electron energy of which has been increased from 2.5 GeV to 3 GeV. The coherence length was determined by single-slit measurement of the visibility of the Fresnel diffraction pattern. The correlated incoherent source size was cross-checked for three different optics: the single slit, beryllium parabolic compound refractive lenses, and the Fresnel zone plate. We concluded that the undulator beamline has an effective incoherent source size (FWHM) of 540 μm (horizontal) × 50 μm (vertical)

  17. Thallium magnesium chloride: A high light yield, large effective atomic number, intrinsically activated crystalline scintillator for X-ray and gamma-ray detection

    Science.gov (United States)

    Fujimoto, Yutaka; Koshimizu, Masanori; Yanagida, Takayuki; Okada, Go; Saeki, Keiichiro; Asai, Keisuke

    2016-09-01

    We report the luminescence and the scintillation properties of a newly developed thallium magnesium chloride (TlMgCl3) crystal. The crystal sample can be easily fabricated from the melt using the Bridgman method. The photoluminescence band appeared near the wavelength of 405 nm under excitation at 230 nm. An X-ray-induced scintillation spectrum showed an intense emission band near the wavelength of 405 nm. The decay time constant was estimated to be approximately 60 ns (∼25%) and 350 ns (∼75%) using a bi-exponential fitting. The scintillation light yield reached 46,000 photons/MeV with an energy resolution of 5% at 662 keV.

  18. Phosphor Scanner For Imaging X-Ray Diffraction

    Science.gov (United States)

    Carter, Daniel C.; Hecht, Diana L.; Witherow, William K.

    1992-01-01

    Improved optoelectronic scanning apparatus generates digitized image of x-ray image recorded in phosphor. Scanning fiber-optic probe supplies laser light stimulating luminescence in areas of phosphor exposed to x rays. Luminescence passes through probe and fiber to integrating sphere and photomultiplier. Sensitivity and resolution exceed previously available scanners. Intended for use in x-ray crystallography, medical radiography, and molecular biology.

  19. X-ray Pulsars

    CERN Document Server

    Walter, Roland

    2016-01-01

    X-ray pulsars shine thanks to the conversion of the gravitational energy of accreted material to X-ray radiation. The accretion rate is modulated by geometrical and hydrodynamical effects in the stellar wind of the pulsar companions and/or by instabilities in accretion discs. Wind driven flows are highly unstable close to neutron stars and responsible for X-ray variability by factors $10^3$ on time scale of hours. Disk driven flows feature slower state transitions and quasi periodic oscillations related to orbital motion and precession or resonance. On shorter time scales, and closer to the surface of the neutron star, X-ray variability is dominated by the interactions of the accreting flow with the spinning magnetosphere. When the pulsar magnetic field is large, the flow is confined in a relatively narrow accretion column, whose geometrical properties drive the observed X-ray emission. In low magnetized systems, an increasing accretion rate allows the ignition of powerful explosive thermonuclear burning at t...

  20. Synchronized ion acceleration by ultraintense slow light and electron source for x-ray production from low-density targets

    Science.gov (United States)

    Brantov, A. V.; Bychenkov, V. Yu

    2017-03-01

    Synchronized proton acceleration by ultraintense slow light in a low-density target Brantov et al (2016 Phys. Rev. Lett. 116 085004) is studied for a circularly polarized laser pulse. This study demonstrates the advantage of circularly polarized light compared with linearly polarized light used for high-energy proton generation. At the same time, high-energy electron production for gamma-ray generation is not sensitive to the polarization of the laser pulse. Both the proton and the electron sources are considered in application to petawatt-class lasers.

  1. Light speed variation from gamma ray burst GRB 160509A

    Science.gov (United States)

    Xu, Haowei; Ma, Bo-Qiang

    2016-09-01

    It is postulated in Einstein's relativity that the speed of light in vacuum is a constant for all observers. However, the effect of quantum gravity could bring an energy dependence of light speed. Even a tiny speed variation, when amplified by the cosmological distance, may be revealed by the observed time lags between photons with different energies from astrophysical sources. From the newly detected long gamma ray burst GRB 160509A, we find evidence to support the prediction for a linear form modification of light speed in cosmological space.

  2. Light speed variation from gamma ray burst GRB 160509A

    CERN Document Server

    Xu, Haowei

    2016-01-01

    It is postulated in Einstein's relativity that the speed of light in vacuum is a constant for all observers. However, the effect of quantum gravity could bring an energy dependence of light speed. Even a tiny speed variation, when amplified by the cosmological distance, may be revealed by the observed time lags between photons with different energies from astrophysical sources. From the newly detected long gamma ray burst GRB~160509A, we find evidence to support the prediction for a linear form modification of light speed in cosmological space.

  3. The pH induced sol-gel transition in skim milk revisited. A detailed study using time-resolved light and x-ray scattering experiments.

    Science.gov (United States)

    Moitzi, Christian; Menzel, Andreas; Schurtenberger, Peter; Stradner, Anna

    2011-03-15

    We present a detailed study of the evolution of the size, structure and stability of casein micelles upon acidification of skim milk typically applied in yogurt-making processes using a combination of time-resolved light and small-angle X-ray scattering experiments. While most of the available light scattering studies on casein acidification have been restricted to transparent and therefore highly diluted samples, we now profit from a newly developed multiangle 3D light scattering instrument, which allows for time-resolved measurements in highly turbid samples. Our experiments clearly demonstrate the presence of two parallel pH-dependent processes, micellar reassembly and aggregation. Using a systematic investigation of the effect of casein concentration, acidification rate, and ionic strength, we are able to decouple these two processes and obtain detailed information about the pH-induced restructuration of the casein micelle structure that occurs prior to destabilization. Moreover, our experiments also unambiguously demonstrate that these micellar reassembly processes are highly concentration dependent, and that typical light scattering studies conducted under highly diluted conditions are resulting in findings that may not be relevant for the situation encountered in industrial processes at higher concentrations. Experiments conducted with covalently cross-linked micelles, where the pH-induced reassembly has been suppressed, further confirm our findings.

  4. The return of the bursts: Thermonuclear flashes from Circinus X-1

    CERN Document Server

    Linares, M; Altamirano, D; Soleri, P; Degenaar, N; Yang, Y; Wijnands, R; Casella, P; Homan, J; Chakrabarty, D; Rea, N; Armas-Padilla, M; Cavecchi, Y; Kalamkar, M; Kaur, R; Patruno, A; van der Klis, M

    2010-01-01

    We report the detection of 15 X-ray bursts with RXTE and Swift observations of the peculiar X-ray binary Circinus X-1 during its May 2010 X-ray re-brightening. These are the first X-ray bursts observed from the source after the initial discovery by Tennant and collaborators, twenty-five years ago. By studying their spectral evolution, we firmly identify nine of the bursts as type I (thermonuclear) X-ray bursts. We obtain an arcsecond location of the bursts that confirms once and for all the identification of Cir X-1 as a type I X-ray burst source, and therefore as a low magnetic field accreting neutron star. The first five bursts observed by RXTE are weak and show approximately symmetric light curves, without detectable signs of cooling along the burst decay. We discuss their possible nature. Finally, we explore a scenario to explain why Cir X-1 shows thermonuclear bursts now but not in the past, when it was extensively observed and accreting at a similar rate.

  5. X-Ray Protection

    Science.gov (United States)

    1955-01-01

    15,000. • When developed In Kodak liquid X-ray developer for 5 min at a temperature of 200 C. b Film sensitivities vary with photon energy by the...for example temporomandibular -joint exposures where a skin dose of 25 r or more may be obtained during a single exposure with 65 kvp, 1.5 mm aluminum...communication. W. J. Updegrave, Temporomandibular articulation-X-ray examina- tion, Dental Radiography and Photography 26, No. 3, 41 (1953). H. 0. Wyckoff, R. J

  6. Lacquer polishing of X-ray optics

    Science.gov (United States)

    Catura, R. C.; Joki, E. G.; Roethig, D. T.; Brookover, W. J.

    1987-01-01

    Techniques for polishing figured X-ray optics by a lacquer-coating process are described. This acrylic lacquer coating has been applied with an optical quality of an eighth-wave in red light and very effectively covers surface roughness with spatial wavelengths less than about 0.2 mm. Tungsten films have been deposited on the lacquer coatings to provide highly efficient X-ray reflectivity.

  7. 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.; van der Klis, M.; Watts, A.; Wijnands, R.; Linares, M.; Casella, P.; Rea, N.; Soleri, P.; Markwardt, C.; Strohmayer, T.; Heinke, C.

    2010-01-01

    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,

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

    CERN Document Server

    D'Aì, A; La Parola, V; Segreto, A

    2016-01-01

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

  9. A Monte Carlo study of x-ray fluorescence in x-ray detectors.

    Science.gov (United States)

    Boone, J M; Seibert, J A; Sabol, J M; Tecotzky, M

    1999-06-01

    Advances in digital x-ray detector systems have led to a renewed interest in the performance of x-ray phosphors and other detector materials. Indirect flat panel x-ray detector and charged coupled device (CCD) systems require a more technologically challenging geometry, whereby the x-ray beam is incident on the front side of the scintillator, and the light produced must diffuse to the back surface of the screen to reach the photoreceptor. Direct detector systems based on selenium have also enjoyed a growing interest, both commercially and academically. Monte Carlo simulation techniques were used to study the x-ray scattering (Rayleigh and Compton) and the more prevalent x-ray fluorescence properties of seven different x-ray detector materials, Gd2O2S, CsI, Se, BaFBr, YTaO4, CaWO4, and ThO2. The redistribution of x-ray energy, back towards the x-ray source, in a forward direction through the detector, and lateral reabsorption in the detector was computed under monoenergetic conditions (1 keV to 130 keV by 1 keV intervals) with five detector thicknesses, 30, 60, 90, 120, and 150 mg/cm2 (Se was studied from 30 to 1000 mg/cm2). The radial distribution (related to the point spread function) of reabsorbed x-ray energy was also determined. Representative results are as follows: At 55 keV, more (31.3%) of the incident x-ray energy escaped from a 90 mg/cm2Gd2O2S detector than was absorbed (27.9%). Approximately 1% of the total absorbed energy was reabsorbed greater than 0.5 mm from the primary interaction, for 90 mg/cm2 CsI exposed at 100 kVp. The ratio of reabsorbed secondary (fluorescence + scatter) radiation to the primary radiation absorbed in the detectors (90 mg/cm2) (S/P) was determined as 10%, 16%, 2%, 12%, 3%, 3%, and 0.3% for a 100 kVp tungsten anode x-ray spectrum, for the Gd2O2S, CsI, Se, BaFBr, YTaO4, CaWO4, and ThO2 detectors, respectively. The results indicate significant x-ray fluorescent escape and reabsorption in common x-ray detectors. These findings

  10. X-ray microscopy as an approach to increasing accuracy and efficiency of serial block-face imaging for correlated light and electron microscopy of biological specimens.

    Science.gov (United States)

    Bushong, Eric A; Johnson, Donald D; Kim, Keun-Young; Terada, Masako; Hatori, Megumi; Peltier, Steven T; Panda, Satchidananda; Merkle, Arno; Ellisman, Mark H

    2015-02-01

    The recently developed three-dimensional electron microscopic (EM) method of serial block-face scanning electron microscopy (SBEM) has rapidly established itself as a powerful imaging approach. Volume EM imaging with this scanning electron microscopy (SEM) method requires intense staining of biological specimens with heavy metals to allow sufficient back-scatter electron signal and also to render specimens sufficiently conductive to control charging artifacts. These more extreme heavy metal staining protocols render specimens light opaque and make it much more difficult to track and identify regions of interest (ROIs) for the SBEM imaging process than for a typical thin section transmission electron microscopy correlative light and electron microscopy study. We present a strategy employing X-ray microscopy (XRM) both for tracking ROIs and for increasing the efficiency of the workflow used for typical projects undertaken with SBEM. XRM was found to reveal an impressive level of detail in tissue heavily stained for SBEM imaging, allowing for the identification of tissue landmarks that can be subsequently used to guide data collection in the SEM. Furthermore, specific labeling of individual cells using diaminobenzidine is detectable in XRM volumes. We demonstrate that tungsten carbide particles or upconverting nanophosphor particles can be used as fiducial markers to further increase the precision and efficiency of SBEM imaging.

  11. Crystallization and preliminary X-ray diffraction analysis of the peripheral light-harvesting complex LH2 from Marichromatium purpuratum.

    Science.gov (United States)

    Cranston, Laura J; Roszak, Aleksander W; Cogdell, Richard J

    2014-06-01

    LH2 from the purple photosynthetic bacterium Marichromatium (formerly known as Chromatium) purpuratum is an integral membrane pigment-protein complex that is involved in harvesting light energy and transferring it to the LH1-RC `core' complex. The purified LH2 complex was crystallized using the sitting-drop vapour-diffusion method at 294 K. The crystals diffracted to a resolution of 6 Å using synchrotron radiation and belonged to the tetragonal space group I4, with unit-cell parameters a=b=109.36, c=80.45 Å. The data appeared to be twinned, producing apparent diffraction symmetry I422. The tetragonal symmetry of the unit cell and diffraction for the crystals of the LH2 complex from this species reveal that this complex is an octamer.

  12. Research and development for X-ray optics and diagnostics on the linac coherent light source (LCLS)

    CERN Document Server

    Wootton, A; Barbee, T W; Bionta, R; Jankowski, A; London, R; Ryutov, D; Shepherd, R; Shlyaptsev, V; Tatchyn, R; Toor, A

    2002-01-01

    The Linac Coherent Light Source is a 1.5-15 A-wavelength free-electron laser (FEL), currently proposed for the Stanford Linear Accelerator Center. The photon output consists of high brightness, transversely coherent pulses with duration <300 fs, together with a broad spontaneous spectrum with total power comparable to the coherent output. The output fluence, and pulse duration, pose special challenges for optical component and diagnostic designs. We first discuss the specific requirements for the initial scientific experiments, and our proposed solutions. We then describe the supporting research and development program that includes: experimental and theoretical material damage studies; high-resolution multilayer design, fabrication, and testing; replicated closed-form optics design and manufacturing; BeB manufacturing; and low-Z Fresnel lens design, fabrication and testing. Finally, some novel concepts for optical components are presented.

  13. Ultrafast Spin-State Dynamics in Transition-Metal Complexes Triggered by Soft-X-Ray Light

    Science.gov (United States)

    Wang, Huihui; Bokarev, Sergey I.; Aziz, Saadullah G.; Kühn, Oliver

    2017-01-01

    Recent advances in attosecond physics provide access to the correlated motion of valence and core electrons on their intrinsic timescales. For valence excitations, processes related to the electron spin are usually driven by nuclear motion. For core-excited states, where the core hole has a nonzero angular momentum, spin-orbit coupling is strong enough to drive spin flips on a much shorter time scale. Here, unprecedented short spin crossover is demonstrated for L -edge (2 p →3 d ) excited states of a prototypical Fe(II) complex. It occurs on a time scale, which is faster than the core-hole lifetime of about 4 fs and can be manipulated by the excitation conditions. A detailed analysis of such phenomena will help to gain a fundamental understanding of spin-crossover processes and establish the basis for their control by light.

  14. Light speed variation from gamma-ray bursts

    CERN Document Server

    Xu, Haowei

    2016-01-01

    The effect of quantum gravity can bring a tiny light speed variation which is detectable through energetic photons propagating from gamma ray bursts (GRBs) to an observer such as the space observatory. Through an analysis of the energetic photon data of the GRBs observed by the Fermi Gamma-ray Space Telescope (FGST), we reveal a surprising regularity of the observed time lags between photons of different energies with respect to the Lorentz violation factor due to the light speed energy dependence. Such regularity suggests a linear form correction of the light speed $v(E)=c(1-E/E_{\\rm LV})$, where $E$ is the photon energy and $E_{\\rm LV}=(3.60 \\pm 0.26) \\times 10^{17}~ \\rm GeV$ is the Lorentz violation scale measured by the energetic photon data of GRBs. The results support an energy dependence of the light speed in cosmological space.

  15. Nonrelativistic quantum X-ray physics

    CERN Document Server

    Hau-Riege, Stefan P

    2015-01-01

    Providing a solid theoretical background in photon-matter interaction, Nonrelativistic Quantum X-Ray Physics enables readers to understand experiments performed at XFEL-facilities and x-ray synchrotrons. As a result, after reading this book, scientists and students will be able to outline and perform calculations of some important x-ray-matter interaction processes. Key features of the contents are that the scope reaches beyond the dipole approximation when necessary and that it includes short-pulse interactions. To aid the reader in this transition, some relevant examples are discussed in detail, while non-relativistic quantum electrodynamics help readers to obtain an in-depth understanding of the formalisms and processes. The text presupposes a basic (undergraduate-level) understanding of mechanics, electrodynamics, and quantum mechanics. However, more specialized concepts in these fields are introduced and the reader is directed to appropriate references. While primarily benefiting users of x-ray light-sou...

  16. Very Early Optical Afterglows for Geometric Models of X-ray Flashes and X-ray Rich GRBs

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    If X-ray flashes (XRFs) and X-ray rich Gamma-ray Bursts (XRRGs) have the same origin as the Gamma-ray bursts (GRBs) but are viewed off-center from structured jets, their early afterglows may differ from those of GRBs, and when the ultra-relativistic outflow interacts with the surrounding medium, there are two shocks formed, a forward shock (FS), and a reverse shock (RS). We calculate numerically the early afterglow powered by uniform jets, Gaussian jets and power-law jets in the forward-reverse shock scenario. A set of differential equations govern the dynamical evolution. The synchrotron self-Compton effect has been taken into account in the calculation. In the uniform jets, the very early afterglows of XRRGs and XRFs are significantly lower than the GRBs and the observed peak times of RS emission are later in the interstellar medium environment. The RS components in XRRGs and XRFs are difficult to detect, but in the stellar wind environment, the reduction of the very early flux and the delay of the RS peak time are not so remarkable. In nonuniform jets (Gaussian and power-law jets), where there are emission materials on the line of sight, the very early light curve resembles equivalent isotropic ejecta in general although the RS flux decay index shows notable deviations if the RS is relativistic (in stellar wind).

  17. XMM-Newton observations of OY Car III: OM light curve modelling, X-ray timing and spectral studies

    CERN Document Server

    Hakala, P; Hakala, Pasi; Ramsay, Gavin

    2003-01-01

    We revisit the XMM-Newton observations of the dwarf nova OY Car taken in July 2000 which occured shortly after an outburst. Ramsay et al (2001a) found a prominent energy dependent modulation at a period of 2240 sec: this modulation was only seen for app. 1/3 of the observation duration. In our new analysis, we examine this time interval in greater detail. In addition to the 2240 sec period we find evidence for other periods, the most prominent being near 3500 sec. Both these modulations are most likely due to changes in photoelectric absorption over this period: this is supported by phase-resolved spectroscopy. This may indicate the presence of matter above the accretion disc or a presence of a magnetic accretion curtain. In this case the 2240 sec period could represent a spin period of the white dwarf and the 3500 sec period a beat period between the spin and orbital periods. We also model the B band and UV eclipse profiles and light curves using a new technique to map the spatial extent of the accretion dis...

  18. X-ray bursters and the X-ray sources of the galactic bulge

    Science.gov (United States)

    Lewin, W. H. G.; Joss, P. C.

    1981-01-01

    An attempt is made to distill from observational and theoretical information on the galactic bulge X-ray sources in general, and on the X-ray burst sources in particular, those aspects which seem to have the greatest relevance to the understanding of these sources. Galactic bulge sources appear to be collapsed objects of roughly solar mass, in most cases neutron stars, which are accreting matter from low-mass stellar companions. Type I bursts seem to result from thermonuclear flashes in the surface layers of some of these neutron stars, while the type II bursts from the Rapid Burster are almost certainly due to an instability in the accretion flow onto a neutron star. It is concluded that the studies cited offer a new and powerful observational handle on the fundamental properties of neutron stars and of the interacting binary systems in which they are often contained.

  19. X-ray Observations of Neutron Star Binaries: Evidence for Millisecond Spins

    OpenAIRE

    Strohmayer, Tod E.

    2001-01-01

    High amplitude X-ray brightness oscillations during thermonuclear X-ray bursts were discovered with the Rossi X-ray Timing Explorer (RXTE) in early 1996. Spectral and timing evidence strongly supports the conclusion that these oscillations are caused by rotational modulation of the burst emission and that they reveal the spin frequency of neutron stars in low mass X-ray binaries (LMXB), a long sought goal of X-ray astronomy. I briefly review the status of our knowledge of these oscillations. ...

  20. Two distinct phases of hard x-ray emissions in a solar eruptive flare

    CERN Document Server

    Joshi, Bhuwan; Cho, K -S; Bong, S -C; Moon, Y -J; Lee, Jeongwoo; Somov, B V; Manoharan, P K; Kim, Y -H

    2008-01-01

    We present a detailed analysis of the evolution of an M7.6 flare that occurred near the south-east limb on October 24, 2003 utilizing a multi-wavelength data set. Preflare images at TRACE 195 A show that the bright and complex system of coronal loops already existed at the flaring site. The X-ray light curves clearly reveal two phases of flare evolution. The emission during the first phase is seen in GOES and RHESSI measurements at energies below 25 keV, while the second phase is evident in all the X-ray energies as high as 300 keV. The first phase is gradual whereas the second phase shows impulsive emission with several individual hard X-ray bursts. The first phase starts with the appearance of an X-ray loop-top (LT) source in RHESSI images below 25 keV. About 5 minute later, the TRACE 195 A images show an intense emission that is cospatial with RHESSI LT source. This hot and diffuse TRACE emission is attributed to the existence of 15-20 MK plasma, heated directly from the primary energy source. Both X-ray a...

  1. X-Ray Astronomy

    Science.gov (United States)

    Wu, S. T.

    2000-01-01

    Dr. S. N. Zhang has lead a seven member group (Dr. Yuxin Feng, Mr. XuejunSun, Mr. Yongzhong Chen, Mr. Jun Lin, Mr. Yangsen Yao, and Ms. Xiaoling Zhang). This group has carried out the following activities: continued data analysis from space astrophysical missions CGRO, RXTE, ASCA and Chandra. Significant scientific results have been produced as results of their work. They discovered the three-layered accretion disk structure around black holes in X-ray binaries; their paper on this discovery is to appear in the prestigious Science magazine. They have also developed a new method for energy spectral analysis of black hole X-ray binaries; four papers on this topics were presented at the most recent Atlanta AAS meeting. They have also carried Monte-Carlo simulations of X-ray detectors, in support to the hardware development efforts at Marshall Space Flight Center (MSFC). These computation-intensive simulations have been carried out entirely on the computers at UAH. They have also carried out extensive simulations for astrophysical applications, taking advantage of the Monte-Carlo simulation codes developed previously at MSFC and further improved at UAH for detector simulations. One refereed paper and one contribution to conference proceedings have been resulted from this effort.

  2. X-ray Flashes from Off-axis Nonuniform Jets

    Institute of Scientific and Technical Information of China (English)

    Zhi-Ping Jin; Da-Ming Wei

    2004-01-01

    It has been widely believed that the outflows in gamma-ray bursts are jetted and some jets may have structures like ∈(θ) ∝θ-κ. We check the possibility that X-ray flashes come from such jets. Both qualitative and quantitative analyses have shown that this model can reproduce most of the observational features of both X-ray flashes and gamma-ray bursts. Using the usual parameters of gamma-ray bursts, we have carried out numerical calculations for both uniform and nonuniform jets, of their fluxes, spectra and peak energies. It seems that nonuniform jets are more appropriate to these observational properties than uniform jets. We have also shown that in our model the observational ratio of gamma-ray bursts to X-ray flashes is about a few units.

  3. Hard X-ray emission from neutron star X-ray binaries

    Energy Technology Data Exchange (ETDEWEB)

    Di Salvo, T.; Santangelo, A.; Segreto, A

    2004-06-01

    In this paper we review our current knowledge of the hard X-ray emission properties of accreting X-ray Binary Pulsars and old accreting neutron stars in Low Mass X-ray Binaries in light of 7 years of BeppoSAX and RXTE observations. The paper is divided in two parts. In the first part we review the more recent findings on the phase-dependent broad band continua and cyclotron resonance scattering features observed in many systems of the X-ray Binary Pulsar class. In the second part we review the hard X-ray emission of LMXRB focussing on the hard X-ray components extending up to energies of a few hundred keV that have been clearly detected in sources of both the atoll and Z classes. The presence and characteristics of these hard emission components are then discussed in relation to source properties and spectral state. We, also, briefly mention models that have been proposed for the hard X-ray emission of neutron star X-ray binaries.

  4. The Cambridge-Cambridge X-ray Serendipity Survey: I X-ray luminous galaxies

    Science.gov (United States)

    Boyle, B. J.; Mcmahon, R. G.; Wilkes, B. J.; Elvis, M.

    1994-01-01

    We report on the first results obtained from a new optical identification program of 123 faint X-ray sources with S(0.5-2 keV) greater than 2 x 10(exp -14) erg/s/sq cm serendipitously detected in ROSAT PSPC pointed observations. We have spectroscopically identified the optical counterparts to more than 100 sources in this survey. Although the majority of the sample (68 objects) are QSO's, we have also identified 12 narrow emission line galaxies which have extreme X-ray luminosities (10(exp 42) less than L(sub X) less than 10(exp 43.5) erg/s). Subsequent spectroscopy reveals them to be a mixture of star-burst galaxies and Seyfert 2 galaxies in approximately equal numbers. Combined with potentially similar objects identified in the Einstein Extended Medium Sensitivity Survey, these X-ray luminous galaxies exhibit a rate of cosmological evolution, L(sub X) varies as (1 + z)(exp 2.5 +/- 1.0), consistent with that derived for X-ray QSO's. This evolution, coupled with the steep slope determined for the faint end of the X-ray luminosity function (Phi(L(sub X)) varies as L(sub X)(exp -1.9)), implies that such objects could comprise 15-35% of the soft (1-2 keV) X-ray background.

  5. Effective interaction of charged platelets in aqueous solution: investigations of colloid laponite suspensions by static light scattering and small-angle x-ray scattering.

    Science.gov (United States)

    Li, Li; Harnau, L; Rosenfeldt, S; Ballauff, M

    2005-11-01

    We study dilute aqueous solutions of charged disklike mineral particles (laponite) by a combination of static light scattering (SLS) and small-angle x-ray scattering (SAXS). Laponite solutions are known to form gels above a certain critical concentration that must be described as nonequilibrium states. Here we focus on the investigation by SLS and SAXS at concentrations below gelation (cLaponite platelets as well as the structure factor describing their interaction at finite concentration. A detailed analysis of the combined sets of data proves that the solutions are in a well-defined equilibrium state. Moreover, this analysis demonstrates the internal consistency and accuracy of the scattering functions obtained at finite concentrations. We find that laponite particles interact through an effective pair potential that is attractive on short range but repulsive on longer range. This finding demonstrates that Laponite solutions exhibit only a limited stability at the concentration of added salt used herein. Raising the ionic strength to 0.005M already leads to slow flocculation as is evidenced from the enhanced scattering intensity at smallest scattering angles. All data strongly suggest that the gelation occurring at higher concentration is related to aggregation.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-05-21

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

  7. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... fracture. guide orthopedic surgery, such as spine repair/fusion, joint replacement and fracture reductions. look for injury, ... and Media Arthritis X-ray, Interventional Radiology and Nuclear Medicine Radiation Safety Images related to X-ray ( ...

  8. Abdomen X-Ray (Radiography)

    Science.gov (United States)

    ... Professions Site Index A-Z X-ray (Radiography) - Abdomen Abdominal x-ray uses a very small dose ... to produce pictures of the inside of the abdominal cavity. It is used to evaluate the stomach, liver, ...

  9. Bone X-Ray (Radiography)

    Medline Plus

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

  10. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... patient. top of page How does the procedure work? X-rays are a form of radiation like ... very controlled x-ray beams and dose control methods to minimize stray (scatter) radiation. This ensures that ...

  11. Panoramic Dental X-Ray

    Science.gov (United States)

    ... Physician Resources Professions Site Index A-Z Panoramic Dental X-ray Panoramic dental x-ray uses a ... Your e-mail address: Personal message (optional): Bees: Wax: Notice: RadiologyInfo respects your privacy. Information entered here ...

  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. 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.

  14. 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 ...

  15. Uhuru observations of the Norma X-ray burster

    Science.gov (United States)

    Grindlay, J.; Gursky, H.

    1976-01-01

    Four X-ray bursts consistent with a single source in Norma are reported which were discovered by reexamining Uhuru data obtained between 1970 and 1973. The temporal and spectral characteristics of the bursts are described and shown to be similar to those displayed by bursts from the globular cluster NGC 6224. An error box of the source location is given, and it is found that both the position and intensity of the four bursts are consistent with those of 10 bursts detected by the Vela satellites in 1976. It is concluded that the source is the same as that observed by the Vela and is an X-ray burster with characteristics similar to those of certain other bursters. XB 1608-52 is suggested as the designation of this burster, possible burst models are considered, and it is noted that the error box of the present source contains an identified globular cluster.

  16. 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.

  17. X-Ray Exam: Hip

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Hip KidsHealth > For Parents > X-Ray Exam: Hip A A A What's in ... español Radiografía: cadera What It Is A hip X-ray is a safe and painless test that ...

  18. X-Ray Exam: Finger

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Finger KidsHealth > For Parents > X-Ray Exam: Finger A A A What's in ... español Radiografía: dedo What It Is A finger X-ray is a safe and painless test that ...

  19. X-Ray Exam: Foot

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Foot KidsHealth > For Parents > X-Ray Exam: Foot A A A What's in ... español Radiografía: pie What It Is A foot X-ray is a safe and painless test that ...

  20. X-Ray Exam: Wrist

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Wrist KidsHealth > For Parents > X-Ray Exam: Wrist A A A What's in ... español Radiografía: muñeca What It Is A wrist X-ray is a safe and painless test that ...

  1. X-Ray Exam: Ankle

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Ankle KidsHealth > For Parents > X-Ray Exam: Ankle A A A What's in ... español Radiografía: tobillo What It Is An ankle X-ray is a safe and painless test that ...

  2. X-Ray Exam: Pelvis

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Pelvis KidsHealth > For Parents > X-Ray Exam: Pelvis A A A What's in ... español Radiografía: pelvis What It Is A pelvis X-ray is a safe and painless test that ...

  3. X-Ray Exam: Forearm

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Forearm KidsHealth > For Parents > X-Ray Exam: Forearm A A A What's in ... español Radiografía: brazo What It Is A forearm X-ray is a safe and painless test that ...

  4. X-ray selected BALQSOs

    CERN Document Server

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

    2016-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Martin; /SLAC

    2010-12-16

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

  6. GRB 060714: No Clear Dividing Line Between Prompt Emission and X-ray Flares

    CERN Document Server

    Krimm, H A; Marshal, F; Perri, M; Barthelmy, S D; Burrows, D N; Gehrels, N; Mészáros, P; Morris, D

    2007-01-01

    The long gamma-ray burst GRB 060714 was observed to exhibit a series of five X-ray flares beginning ~70 s after the burst trigger T0 and continuing until T0 + ~200 s. The first two flares were detected by the Burst Alert Telescope (BAT) on the Swift satellite, before Swift had slewed to the burst location, while the last three flares were strongly detected by the X-Ray Telescope (XRT) but only weakly detected by the BAT. This burst provides an unusual opportunity to track a complete sequence of flares over a wide energy range. The flares were very similar in their light curve morphology, showing power-law rise and fall components, and in most cases significant sub-structure. The flares also showed strong evolution with time, both spectrally and temporally. The small time scale and large amplitude variability observed are incompatible with an external shock origin for the flares, and support instead late time sporadic activity either of the central source or of localized dissipation events within the outflow. ...

  7. X-ray today

    Energy Technology Data Exchange (ETDEWEB)

    Neitzel, U. [Philips Medical Systems, Hamburg (Germany)

    2001-09-01

    The interest attracted by the new imaging modalities tends to overshadow the continuing importance of projection radiography and fluoroscopy. Nevertheless, projection techniques still represent by far the greatest proportion of diagnostic imaging examinations, and play an essential role in the growing number of advanced interventional procedures. This article describes some of the latest developments in X-ray imaging technology, using two products from the Philips range as examples: the Integris Allura cardiovascular system with 3D image reconstruction, and the BV Pulsera: a high-end, multi-functional mobile C-arm system with cardiac capabilities. (orig.)

  8. SMM x ray polychromator

    Science.gov (United States)

    Saba, J. L. R.

    1993-01-01

    The objective of the X-ray Polychromator (XRP) experiment was to study the physical properties of solar flare plasma and its relation to the parent active region to understand better the flare mechanism and related solar activity. Observations were made to determine the temperature, density, and dynamic structure of the pre-flare and flare plasma as a function of wavelength, space and time, the extent to which the flare plasma departs from thermal equilibrium, and the variation of this departure with time. The experiment also determines the temperature and density structure of active regions and flare-induced changes in the regions.

  9. X-Ray Detector Simulations - Oral Presentation

    Energy Technology Data Exchange (ETDEWEB)

    Tina, Adrienne [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-20

    The free-electron laser at LCLS produces X-Rays that are used in several facilities. This light source is so bright and quick that we are capable of producing movies of objects like proteins. But making these movies would not be possible without a device that can detect the X-Rays and produce images. We need X-Ray cameras. The challenges LCLS faces include the X-Rays’ high repetition rate of 120 Hz, short pulses that can reach 200 femto-seconds, and extreme peak brightness. We need detectors that are compatible with this light source, but before they can be used in the facilities, they must first be characterized. My project was to do just that, by making a computer simulation program. My presentation discusses the individual detectors I simulated, the details of my program, and how my project will help determine which detector is most useful for a specific experiment.

  10. High-resolution detectors for soft X-ray spectroscopy

    OpenAIRE

    Soman, Matthew

    2014-01-01

    Resonant Inelastic X-ray Scattering (RIXS) is a modern soft X-ray spectroscopy technique used to investigate the structure of and excitations in materials. It requires high resolution spectrometers and a brilliant, tunable, X-ray source and therefore is carried out at spectrometers such as SAXES at the Swiss Light Source Light, a synchrotron at the Paul Scherrer Institut.\\ud \\ud SAXES uses a grating to disperse X-rays scattered from a sample across a position sensitive detector, a Charge-Coup...

  11. Reductive and oxidative degradation of iopamidol, iodinated X-ray contrast media, by Fe(III)-oxalate under UV and visible light treatment.

    Science.gov (United States)

    Zhao, Cen; Arroyo-Mora, Luis E; DeCaprio, Anthony P; Sharma, Virender K; Dionysiou, Dionysios D; O'Shea, Kevin E

    2014-12-15

    Iopamidol, widely employed as iodinated X-ray contrast media (ICM), is readily degraded in a Fe(III)-oxalate photochemical system under UV (350 nm) and visible light (450 nm) irradiation. The degradation is nicely modeled by pseudo first order kinetics. The rates of hydroxyl radical (OH) production for Fe(III)-oxalate/H2O2/UV (350 nm) and Fe(III)-oxalate/H2O2/visible (450 nm) systems were 1.19 ± 0.12 and 0.30 ± 0.01 μM/min, respectively. The steady-state concentration of hydroxyl radical (OH) for the Fe(III)-oxalate/H2O2/UV (350 nm) conditions was 10.88 ± 1.13 × 10(-14) M and 2.7 ± 0.1 × 10(-14) M for the Fe(III)-oxalate/H2O2/visible (450 nm). The rate of superoxide anion radical (O2(-)) production under Fe(III)-oxalate/H2O2/UV (350 nm) was 0.19 ± 0.02 μM/min with a steady-state concentration of 5.43 ± 0.473 × 10(-10) M. Detailed product studies using liquid chromatography coupled to Q-TOF/MS demonstrate both reduction (multiple dehalogenations) and oxidation (aromatic ring and side chains) contribute to the degradation pathways. The reduction processes appear to be initiated by the carbon dioxide anion radical (CO2(-)) while oxidation processes are consistent with OH initiated reaction pathways. Unlike most advanced oxidation processes the Fe(III)-oxalate/H2O2/photochemical system can initiate to both reductive and oxidative degradation processes. The observed reductive dehalogenation is an attractive remediation strategy for halogenated organic compounds as the process can dramatically reduce the formation of the problematic disinfection by-products often associated with oxidative treatment processes.

  12. 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

    Science.gov (United States)

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

    2010-06-01

    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, 58, Altamirano et al. 2008, ApJL 674, 45 and Gavriil et al. 2007, ApJ 669, 22). On June 12th, 2010 (10h 13m 00s UT), a ~10 ks long pointed RXTE observation was performed.

  13. Low energy x-ray spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Woodruff, W.R.

    1981-06-05

    A subkilovolt spectrometer has been produced to permit high-energy-resolution, time-dependent x-ray intensity measurements. The diffracting element is a curved mica (d = 9.95A) crystal. To preclude higher order (n > 1) diffractions, a carbon x-ray mirror that reflects only photons with energies less than approx. 1.1 keV is utilized ahead of the diffracting element. The nominal energy range of interest is 800 to 900 eV. The diffracted photons are detected by a gold-surface photoelectric diode designed to have a very good frequency response, and whose current is recorded on an oscilloscope. A thin, aluminium light barrier is placed between the diffracting crystal and the photoelectric diode detector to keep any uv generated on or scattered by the crystal from illuminating the detector. High spectral energy resolution is provided by many photocathodes between 8- and 50-eV wide placed serially along the diffracted x-ray beam at the detector position. The spectrometer was calibrated for energy and energy dispersion using the Ni L..cap alpha../sub 1/ /sub 2/ lines produced in the LLNL IONAC accelerator and in third order using a molybdenum target x-ray tube. For the latter calibration the carbon mirror was replaced by one surfaced with rhodium to raise the cut-off energy to about 3 keV. The carbon mirror reflection dependence on energy was measured using one of our Henke x-ray sources. The curved mica crystal diffraction efficiency was measured on our Low-Energy x-ray (LEX) machine. The spectrometer performs well although some changes in the way the x-ray mirror is held are desirable. 16 figures.

  14. X-ray Properties of an Unbiased Hard X-ray Detected Sample of AGN

    Science.gov (United States)

    Winter, Lisa M.; Mushotzky, Richard F.; Tueller, Jack; Markwardt, Craig

    2007-01-01

    The SWIFT gamma ray observatory's Burst Alert Telescope (BAT) has detected a sample of active galactic nuclei (AGN) based solely on their hard X-ray flux (14-195keV). In this paper, we present for the first time XMM-Newton X-ray spectra for 22 BAT AGXs with no previously analyzed X-ray spectra. If our sources are a representative sample of the BAT AGN, as we claim, our results present for the first time global X-ray properties of an unbiased towards absorption (n(sub H) = 0.03), AGN sample. We find 9/22 low absorption (n(sub H) 2.0 keV. Five of the complex sources (NGC 612, ESO 362-G018, MRK 417, ESO 506-G027, and NGC 6860) are classified as Compton-thick candidates. Further, we find four more sources (SWIFT J0641.3+3257, SWIFT J0911.2+4533, SWIFT J1200.8+0650, and NGC 4992) with properties consistent with the hidden/buried AGN reported by Ueda et al. (2007). Finally, we include a comparison of the XMM EPIC spectra with available SWIFT X-ray Telescope (XRT) observations. From these comparisons, we find 6/16 sources with varying column densities, 6/16 sources with varying power law indices, and 13/16 sources with varying fluxes, over periods of hours to months. Flux and power law index are correlated for objects where both parameters vary.

  15. Nonlinear X-ray Compton Scattering

    CERN Document Server

    Fuchs, Matthias; Chen, Jian; Ghimire, Shambhu; Shwartz, Sharon; Kozina, Michael; Jiang, Mason; Henighan, Thomas; Bray, Crystal; Ndabashimiye, Georges; Bucksbaum, P H; Feng, Yiping; Herrmann, Sven; Carini, Gabriella; Pines, Jack; Hart, Philip; Kenney, Christopher; Guillet, Serge; Boutet, Sebastien; Williams, Garth; Messerschmidt, Marc; Seibert, Marvin; Moeller, Stefan; Hastings, Jerome B; Reis, David A

    2015-01-01

    X-ray scattering is a weak linear probe of matter. It is primarily sensitive to the position of electrons and their momentum distribution. Elastic X-ray scattering forms the basis of atomic structural determination while inelastic Compton scattering is often used as a spectroscopic probe of both single-particle excitations and collective modes. X-ray free-electron lasers (XFELs) are unique tools for studying matter on its natural time and length scales due to their bright and coherent ultrashort pulses. However, in the focus of an XFEL the assumption of a weak linear probe breaks down, and nonlinear light-matter interactions can become ubiquitous. The field can be sufficiently high that even non-resonant multiphoton interactions at hard X-rays wavelengths become relevant. Here we report the observation of one of the most fundamental nonlinear X-ray-matter interactions, the simultaneous Compton scattering of two identical photons producing a single photon at nearly twice the photon energy. We measure scattered...

  16. Ultrafast X-Ray Coherent Control

    Energy Technology Data Exchange (ETDEWEB)

    Reis, David

    2009-05-01

    This main purpose of this grant was to develop the nascent eld of ultrafast x-ray science using accelerator-based sources, and originally developed from an idea that a laser could modulate the di racting properties of a x-ray di racting crystal on a fast enough time scale to switch out in time a shorter slice from the already short x-ray pulses from a synchrotron. The research was carried out primarily at the Advanced Photon Source (APS) sector 7 at Argonne National Laboratory and the Sub-Picosecond Pulse Source (SPPS) at SLAC; in anticipation of the Linac Coherent Light Source (LCLS) x-ray free electron laser that became operational in 2009 at SLAC (all National User Facilities operated by BES). The research centered on the generation, control and measurement of atomic-scale dynamics in atomic, molecular optical and condensed matter systems with temporal and spatial resolution . It helped develop the ultrafast physics, techniques and scienti c case for using the unprecedented characteristics of the LCLS. The project has been very successful with results have been disseminated widely and in top journals, have been well cited in the eld, and have laid the foundation for many experiments being performed on the LCLS, the world's rst hard x-ray free electron laser.

  17. 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…

  18. X-ray instrumentation for SR beamlines

    CERN Document Server

    Kovalchuk, M V; Zheludeva, S I; Aleshko-Ozhevsky, O P; Arutynyan, E H; Kheiker, D M; Kreines, A Y; Lider, V V; Pashaev, E M; Shilina, N Y; Shishkov, V A

    2000-01-01

    The main possibilities and parameters of experimental X-ray stations are presented: 'Protein crystallography', 'X-ray structure analysis', 'High-precision X-ray optics', 'X-ray crystallography and material science', 'X-ray topography', 'Photoelectron X-ray standing wave' that are being installed at Kurchatov SR source by A.V. Shubnikov Institute of Crystallography.

  19. 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.

  20. X-ray Fluorescence Sectioning

    CERN Document Server

    Cong, Wenxiang

    2012-01-01

    In this paper, we propose an x-ray fluorescence imaging system for elemental analysis. The key idea is what we call "x-ray fluorescence sectioning". Specifically, a slit collimator in front of an x-ray tube is used to shape x-rays into a fan-beam to illuminate a planar section of an object. Then, relevant elements such as gold nanoparticles on the fan-beam plane are excited to generate x-ray fluorescence signals. One or more 2D spectral detectors are placed to face the fan-beam plane and directly measure x-ray fluorescence data. Detector elements are so collimated that each element only sees a unique area element on the fan-beam plane and records the x-ray fluorescence signal accordingly. The measured 2D x-ray fluorescence data can be refined in reference to the attenuation characteristics of the object and the divergence of the beam for accurate elemental mapping. This x-ray fluorescence sectioning system promises fast fluorescence tomographic imaging without a complex inverse procedure. The design can be ad...

  1. X-Ray Attenuation Cell

    Energy Technology Data Exchange (ETDEWEB)

    Ryutov, D.; Toor, A.

    2000-03-03

    To minimize the pulse-to-pulse variation, the LCLS FEL must operate at saturation, i.e. 10 orders of magnitude brighter spectral brilliance than 3rd-generation light sources. At this intensity, ultra-high vacuums and windowless transport are required. Many of the experiments, however, will need to be conducted at a much lower intensity thereby requiring a reliable means to reduce the x-ray intensity by many orders of magnitude without increasing the pulse-to-pulse variation. In this report we consider a possible solution for controlled attenuation of the LCLS x-ray radiation. We suggest using for this purpose a windowless gas-filled cell with the differential pumping. Although this scheme is easily realizable in principle, it has to be demonstrated that the attenuator can be made short enough to be practical and that the gas loads delivered to the vacuum line of sight (LOS) are acceptable. We are not going to present a final, optimized design. Instead, we will provide a preliminary analysis showing that the whole concept is robust and is worth further study. The spatial structure of the LCLS x-ray pulse at the location of the attenuator is shown in Fig. 1. The central high-intensity component, due to the FEL, has a FWHM of {approx}100 {micro}m. A second component, due to the undulator's broad band spontaneous radiation is seen as a much lower intensity ''halo'' with a FWHM of 1 mm. We discuss two versions of the attenuation cell. The first is directed towards a controlled attenuation of the FEL up to the 4 orders of magnitude in the intensity, with the spontaneous radiation halo being eliminated by collimators. In the second version, the spontaneous radiation is not sacrificed but the FEL component (as well as the first harmonic of the spontaneous radiation) gets attenuated by a more modest factor up to 100. We will make all the estimates assuming that the gas used in the attenuator is Xenon and that the energy of the FEL is 8.25 keV. At

  2. Systems and methods for detecting x-rays

    Science.gov (United States)

    Bross, Alan D.; Mellott, Kerry L.; Pla-Dalmau, Anna

    2006-05-02

    Systems and methods for detecting x-rays are disclosed herein. One or more x-ray-sensitive scintillators can be configured from a plurality of heavy element nano-sized particles and a plastic material, such as polystyrene. As will be explained in greater detail herein, the heavy element nano-sized particles (e.g., PbWO4) can be compounded into the plastic material with at least one dopant that permits the plastic material to scintillate. X-rays interact with the heavy element nano-sized particles to produce electrons that can deposit energy in the x-ray sensitive scintillator, which in turn can produce light.

  3. X-ray analysis and optical studies of Dy{sup 3+} doped NaSrB{sub 5}O{sub 9} microstructures for white light generation

    Energy Technology Data Exchange (ETDEWEB)

    Dillip, G.R. [School of Mechanical Engineering and Technology, Yeungnam University, Gyeongsan 712-749 (Korea, Republic of); Ramesh, B.; Madhukar Reddy, C.; Mallikarjuna, K.; Ravi, O. [Department of Physics, Sri Venkateswara University, Tirupati 517 502 (India); Dhoble, S.J. [Department of Physics, RTM Nagpur University, Nagpur 440 033 (India); Joo, S.W. [School of Mechanical Engineering and Technology, Yeungnam University, Gyeongsan 712-749 (Korea, Republic of); Raju, B. Deva Prasad, E-mail: drdevaprasadraju@gmail.com [Department of Future Studies, Sri Venkateswara University, Tirupati 517 502 (India)

    2014-12-05

    Highlights: • NaSrB{sub 5}O{sub 9}:Dy{sup 3+} microstructures were synthesized by solid state reaction. • Crystallite size and lattice strain was estimated by W–H analysis. • Plate-like morphology with monoclinic structure is identified by SEM images. • Highest lifetimes of 931 μS were obtained for this system. - Abstract: A white light emitting phosphor NaSrB{sub 5}O{sub 9}:Dy{sup 3+} was synthesized by a conventional solid state reaction method. The structure of the phosphors was analyzed by powder X-ray diffraction (XRD), revealing that the phosphors crystallized in monoclinic crystal structure with the space group (P2{sub 1}/c). Williamson–Hall (W–H) analysis was used to study the individual contributions of crystallite sizes and lattice strain on the peak broadening of NaSrB{sub 5}O{sub 9}:Dy{sup 3+} phosphors. Monoclinic microstructures of nearly plate-like morphologies were observed in the FE-SEM images. Upon near-UV excitation wavelength (390 nm), the blue emission at ∼482 nm ({sup 6}H{sub 15/2}) and yellow emission at ∼584 nm ({sup 6}H{sub 13/2}) were observed in the phosphors. The critical quenching concentration of Dy{sup 3+} in NaSrB{sub 5}O{sub 9} phosphor was found to be 3 at.% with the critical distance (R{sub c}) of ∼22.30 Å and the corresponding concentration quenching mechanism was testified to be the exchange interaction between the dopant Dy{sup 3+} ions. In order to investigate the application in white LEDs, the Commission International de l’Eclairage (CIE) chromaticity coordinates, color temperature and decay curve measurements of Dy{sup 3+} ions doped NaSrB{sub 5}O{sub 9} phosphors were carried out. The yellow to blue (Y/B) emission integrated intensity ratio is maximum (∼0.9) for all the concentrations, suggesting that the phosphors favor for white illumination.

  4. Broadband turbulent spectra in gamma-ray burst light curves

    Energy Technology Data Exchange (ETDEWEB)

    Van Putten, Maurice H. P. M. [Astronomy and Space Science, Sejong University, 98 Gunja-Dong Gwangin-gu, Seoul 143-747 (Korea, Republic of); Guidorzi, Cristiano; Frontera, Filippo, E-mail: mvp@sejong.ac.kr [Department of Physics and Earth Sciences, University of Ferrara, Via Saragat 1, I-44122 Ferrara (Italy)

    2014-05-10

    Broadband power density spectra offer a window to understanding turbulent behavior in the emission mechanism and, at the highest frequencies, in the putative inner engines powering long gamma-ray bursts (GRBs). We describe a chirp search method alongside Fourier analysis for signal detection in the Poisson noise-dominated, 2 kHz sampled, BeppoSAX light curves. An efficient numerical implementation is described in O(Nnlog n) operations, where N is the number of chirp templates and n is the length of the light-curve time series, suited for embarrassingly parallel processing. For the detection of individual chirps over a 1 s duration, the method is one order of magnitude more sensitive in signal-to-noise ratio than Fourier analysis. The Fourier-chirp spectra of GRB 010408 and GRB 970816 show a continuation of the spectral slope with up to 1 kHz of turbulence identified in low-frequency Fourier analysis. The same continuation is observed in an average spectrum of 42 bright, long GRBs. An outlook on a similar analysis of upcoming gravitational wave data is included.

  5. Ultrafast AMO physics at the LCLS x-ray FEL

    Directory of Open Access Journals (Sweden)

    Bucksbaum P.H.

    2013-08-01

    Full Text Available The Linac Coherent Light Source at the SLAC National Accelerator Laboratory, Stanford University, began operation in 2009 as the world's first hard x-ray free electron laser. Early experiments have concentrated on atomic physics, and have demonstrated several key features of the ultrafast high field x-ray-atom interaction. This paper reviews some of these early results.

  6. An extremely luminous X-ray outburst at the birth of a supernova.

    Science.gov (United States)

    Soderberg, A M; Berger, E; Page, K L; Schady, P; Parrent, J; Pooley, D; Wang, X-Y; Ofek, E O; Cucchiara, A; Rau, A; Waxman, E; Simon, J D; Bock, D C-J; Milne, P A; Page, M J; Barentine, J C; Barthelmy, S D; Beardmore, A P; Bietenholz, M F; Brown, P; Burrows, A; Burrows, D N; Bryngelson, G; Byrngelson, G; Cenko, S B; Chandra, P; Cummings, J R; Fox, D B; Gal-Yam, A; Gehrels, N; Immler, S; Kasliwal, M; Kong, A K H; Krimm, H A; Kulkarni, S R; Maccarone, T J; Mészáros, P; Nakar, E; O'Brien, P T; Overzier, R A; de Pasquale, M; Racusin, J; Rea, N; York, D G

    2008-05-22

    Massive stars end their short lives in spectacular explosions--supernovae--that synthesize new elements and drive galaxy evolution. Historically, supernovae were discovered mainly through their 'delayed' optical light (some days after the burst of neutrinos that marks the actual event), preventing observations in the first moments following the explosion. As a result, the progenitors of some supernovae and the events leading up to their violent demise remain intensely debated. Here we report the serendipitous discovery of a supernova at the time of the explosion, marked by an extremely luminous X-ray outburst. We attribute the outburst to the 'break-out' of the supernova shock wave from the progenitor star, and show that the inferred rate of such events agrees with that of all core-collapse supernovae. We predict that future wide-field X-ray surveys will catch each year hundreds of supernovae in the act of exploding.

  7. Strain and lattice orientation distribution in SiN/Ge complementary metal–oxide–semiconductor compatible light emitting microstructures by quick x-ray nano-diffraction microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chahine, G. A.; Schülli, T. U. [European Synchrotron ESRF, Grenoble 38043 (France); Zoellner, M. H.; Guha, S.; Reich, C.; Zaumseil, P.; Capellini, G. [IHP-Leibniz Institute for Innovative Microelectronics, Frankfurt (Germany); Richard, M.-I. [European Synchrotron ESRF, Grenoble 38043 (France); Aix-Marseille Université, CNRS, IM2NP UMR 7334, Marseille 13397 (France); Schroeder, T. [IHP-Leibniz Institute for Innovative Microelectronics, Frankfurt (Germany); Institute of Physics and Chemistry, Brandenburg Technical University, Cottbus 03046 (Germany)

    2015-02-16

    This paper presents a study of the spatial distribution of strain and lattice orientation in CMOS-fabricated strained Ge microstripes using high resolution x-ray micro-diffraction. The recently developed model-free characterization tool, based on a quick scanning x-ray diffraction microscopy technique can image strain down to levels of 10{sup −5} (Δa/a) with a spatial resolution of ∼0.5 μm. Strain and lattice tilt are extracted using the strain and orientation calculation software package X-SOCS. The obtained results are compared with the biaxial strain distribution obtained by lattice parameter-sensitive μ-Raman and μ-photoluminescence measurements. The experimental data are interpreted with the help of finite element modeling of the strain relaxation dynamics in the investigated structures.

  8. New insights into the quasi-periodic X-ray burster GS 0836-429

    Science.gov (United States)

    Aranzana, E.; Sánchez-Fernández, C.; Kuulkers, E.

    2016-02-01

    GS 0836-429 is a neutron star X-ray transient that displays Type-I X-ray bursts. In 2003 and 2004 it experienced two outbursts in X-rays. We present here an analysis of the system's bursting properties during these outbursts. We studied the evolution of the 2003-2004 outbursts in soft X-rays using RXTE (2.5-12 keV; ASM) and in hard X-rays with INTEGRAL (17-80 keV, IBIS/ISGRI). Using data from the JEM-X monitor onboard INTEGRAL, we studied the bursting properties of the source. We detected 61 Type-I X-ray bursts during the 2004 outburst and confirm that the source displayed a quasi-periodic burst recurrence time of about 2.3 h. We improve the characterisation of the fuel composition, as well as the description of the typical burst durations and fluences. We estimate the average value of α to be 49 ± 3, which describes the ratio of the gravitational energy released between bursts to the nuclear energy released in an X-ray burst. Both this value and the observed burst profiles indicate a regime of a mixed He/H runaway triggered by unstable helium ignition. In addition, we report the detection of four series of double bursts, with burst recurrence times of ≤20 min. The secondary bursts are always shorter and less energetic than the primary and typical bursts from the source. The measured recurrence time in double bursts is too short to allow the accretion of enough fresh material, which is needed to trigger a Type-I X-ray burst. This suggests the presence of leftover, unburned material from the preceding burst, which gets ignited on a time scale of minutes. The energies and time scales of the secondary bursts suggest a lower fraction of hydrogen compared to that estimated for the primary bursts. The persistent emission was roughly constant during the period when the Type I X-ray bursts were detected. We derive an average accretion rate during our observations of ṁ ~ 8% ṁEdd. The spectrum of the persistent emission during these observations can be fit with a non

  9. An Old Story in New Light: X-Ray Powder Diffraction Provides Novel Insights into a Long-Known Organic Solid-State Rearrangement Reaction

    OpenAIRE

    Halasz, Ivan; Cindro, Nikola; Dinnebier, Robert E; Vančik, Hrvoj

    2013-01-01

    The first in situ diffraction study of the long-known solid-state rearrangement of p-bromobenzeneazotribenzoylmethane is reported. This proof-of-principle study demonstrates how modern laboratory X-ray powder diffraction, accompanied by up-to-date processing tools, can be used to monitor and describe mechanisms of organic solid-state reactions while it also underpins its necessity for structural characterisation of in situ formed crystalline phases. (doi: 10.5562/cca2127)

  10. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... bone absorbs much of the radiation while soft tissue, such as muscle, fat and organs, allow more of the x-rays to pass through them. As a result, bones appear white on the x-ray, soft tissue shows up in shades of gray and air ...

  11. X-Ray Diffraction Apparatus

    Science.gov (United States)

    Blake, David F. (Inventor); Bryson, Charles (Inventor); Freund, Friedmann (Inventor)

    1996-01-01

    An x-ray diffraction apparatus for use in analyzing the x-ray diffraction pattern of a sample is introduced. The apparatus includes a beam source for generating a collimated x-ray beam having one or more discrete x-ray energies, a holder for holding the sample to be analyzed in the path of the beam, and a charge-coupled device having an array of pixels for detecting, in one or more selected photon energy ranges, x-ray diffraction photons produced by irradiating such a sample with said beam. The CCD is coupled to an output unit which receives input information relating to the energies of photons striking each pixel in the CCD, and constructs the diffraction pattern of photons within a selected energy range striking the CCD.

  12. Focusing X-Ray Telescopes

    Science.gov (United States)

    O'Dell, Stephen; Brissenden, Roger; Davis, William; Elsner, Ronald; Elvis, Martin; Freeman, Mark; Gaetz, Terrance; Gorenstein, Paul; Gubarev, Mikhall; Jerlus, Diab; Juda, Michael; Kolodziejczak, Jeffrey; Murray, Stephen; Petre, Robert; Podgorski, William; Ramsey, Brian; Reid, Paul; Saha, Timo; Wolk, Scott; Troller-McKinstry, Susan; Weisskopf, Martin; Wilke, Rudeger; Zhang, William

    2010-01-01

    During the half-century history of x-ray astronomy, focusing x-ray telescopes, through increased effective area and finer angular resolution, have improved sensitivity by 8 orders of magnitude. Here, we review previous and current x-ray-telescope missions. Next, we describe the planned next-generation x-ray-astronomy facility, the International X-ray Observatory (IXO). We conclude with an overview of a concept for the next next-generation facility, Generation X. Its scientific objectives will require very large areas (about 10,000 sq m) of highly-nested, lightweight grazing-incidence mirrors, with exceptional (about 0.1-arcsec) resolution. Achieving this angular resolution with lightweight mirrors will likely require on-orbit adjustment of alignment and figure.

  13. 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.

  14. Low- and room-temperature X-ray structures of protein kinase A ternary complexes shed new light on its activity

    Energy Technology Data Exchange (ETDEWEB)

    Kovalevsky, Andrey Y., E-mail: ayk@lanl.gov; Johnson, Hanna [Los Alamos National Laboratory, PO Box 1663, MS M888, Los Alamos, NM 87545 (United States); Hanson, B. Leif [University of Toledo, 2801 West Bancroft Street, Toledo, OH 43606 (United States); Waltman, Mary Jo; Fisher, S. Zoe [Los Alamos National Laboratory, PO Box 1663, MS M888, Los Alamos, NM 87545 (United States); Taylor, Susan [University of San Diego, 9500 Gilman Drive, Leichtag 415, La Jolla, CA 92093 (United States); Langan, Paul [Oak Ridge National Laboratory, PO Box 2008, MS 6475, Oak Ridge, TN 37831 (United States); Los Alamos National Laboratory, PO Box 1663, MS M888, Los Alamos, NM 87545 (United States)

    2012-07-01

    ATP bound in the active site of protein kinase A is readily hydrolysed to ADP and free phosphate by X-ray irradiation at room temperature. The phosphate ion observed in the active site causes a dramatic conformational change of the bound peptide inhibitor. Post-translational protein phosphorylation by protein kinase A (PKA) is a ubiquitous signalling mechanism which regulates many cellular processes. A low-temperature X-ray structure of the ternary complex of the PKA catalytic subunit (PKAc) with ATP and a 20-residue peptidic inhibitor (IP20) at the physiological Mg{sup 2+} concentration of ∼0.5 mM (LT PKA–MgATP–IP20) revealed a single metal ion in the active site. The lack of a second metal in LT PKA–MgATP–IP20 renders the β- and γ-phosphoryl groups of ATP very flexible, with high thermal B factors. Thus, the second metal is crucial for tight positioning of the terminal phosphoryl group for transfer to a substrate, as demonstrated by comparison of the former structure with that of the LT PKA–Mg{sub 2}ATP–IP20 complex obtained at high Mg{sup 2+} concentration. In addition to its kinase activity, PKAc is also able to slowly catalyze the hydrolysis of ATP using a water molecule as a substrate. It was found that ATP can be readily and completely hydrolyzed to ADP and a free phosphate ion in the crystals of the ternary complex PKA–Mg{sub 2}ATP–IP20 by X-ray irradiation at room temperature. The cleavage of ATP may be aided by X-ray-generated free hydroxyl radicals, a very reactive chemical species, which move rapidly through the crystal at room temperature. The phosphate anion is clearly visible in the electron-density maps; it remains in the active site but slides about 2 Å from its position in ATP towards Ala21 of IP20, which mimics the phosphorylation site. The phosphate thus pushes the peptidic inhibitor away from the product ADP, while resulting in dramatic conformational changes of the terminal residues 24 and 25 of IP20. X-ray structures of

  15. X-ray variability with WFXT: AGNs, transients and more

    CERN Document Server

    Paolillo, Maurizio; Allevato, Viola; de Martino, Domitilla; della Valle, Massimo; Papadakis, Iossif; Gilli, Roberto; Tozzi, Paolo

    2010-01-01

    The Wide Field X-ray Telescope (WFXT) is a proposed mission with a high survey speed, due to the combination of large field of view (FOV) and effective area, i.e. grasp, and sharp PSF across the whole FOV. These characteristics make it suitable to detect a large number of variable and transient X-ray sources during its operating lifetime. Here we present estimates of the WFXT capabilities in the time domain, allowing to study the variability of thousand of AGNs with significant detail, as well as to constrain the rates and properties of hundreds of distant, faint and/or rare objects such as X-ray Flashes/faint GRBs, Tidal Disruption Events, ULXs, Type-I bursts etc. The planned WFXT extragalactic surveys will thus allow to trace variable and transient X-ray populations over large cosmological volumes.

  16. X-ray monitoring optical elements

    Energy Technology Data Exchange (ETDEWEB)

    Stoupin, Stanislav; Shvydko, Yury; Katsoudas, John; Blank, Vladimir D.; Terentyev, Sergey A.

    2016-12-27

    An X-ray article and method for analyzing hard X-rays which have interacted with a test system. The X-ray article is operative to diffract or otherwise process X-rays from an input X-ray beam which have interacted with the test system and at the same time provide an electrical circuit adapted to collect photoelectrons emitted from an X-ray optical element of the X-ray article to analyze features of the test system.

  17. X-ray diagnostics for TFTR

    Energy Technology Data Exchange (ETDEWEB)

    von Goeler, S.; Hill, K.W.; Bitter, M.

    1982-12-01

    A short description of the x-ray diagnostic preparation for the TFTR tokamak is given. The x-ray equipment consists of the limiter x-ray monitoring system, the soft x-ray pulse-height-analysis-system, the soft x-ray imaging system and the x-ray crystal spectrometer. Particular attention is given to the radiation protection of the x-ray systems from the neutron environment.

  18. Observationally constraining gravitational wave emission from short gamma-ray burst remnants

    CERN Document Server

    Lasky, Paul D

    2015-01-01

    Observations of short gamma-ray bursts indicate ongoing energy injection following the prompt emission, with the most likely candidate being the birth of a rapidly rotating, highly magnetised neutron star. We utilise X-ray observations of the burst remnant to constrain properties of the nascent neutron star, including its magnetic field-induced ellipticity and the saturation amplitude of various oscillation modes. Moreover, we derive strict upper limits on the gravitational wave emission from these objects by looking only at the X-ray light curve, showing the burst remnants are unlikely to be detected in the near future using ground-based gravitational wave interferometers such as Advanced LIGO.

  19. Unraveling the redox behavior of a CoMoS hydrodesulfurization catalyst : A scanning transmission X-ray microscopy study in the tender X-ray range

    NARCIS (Netherlands)

    Al Samarai, Mustafa; Meirer, Florian; Karunakaran, Chithra; Wang, Jian; Vogt, Eelco T C; Zandbergen, Henny W.; Weber, Thomas; Weckhuysen, Bert M.; De Groot, Frank M F

    2015-01-01

    We visualize the elemental zoning in an alumina-supported cobalt molybdenum sulfide (CoMoS) catalyst with scanning transmission X-ray microscopy (STXM). We use the Canadian Light Source beamline 10-ID's (SM) unique combination of soft X-ray and tender X-ray STXM to determine the spatial variation of

  20. New insights into the quasi-periodic X-ray burster GS 0836-429

    CERN Document Server

    Aranzana, E; Kuulkers, E

    2015-01-01

    GS 0836-429 is a neutron star X-ray transient that displays Type-I X-ray bursts. In 2003 and 2004 it experienced two outbursts in X-rays. We present here an analysis of the system bursting properties during these outbursts. We studied the evolution of the 2003-2004 outbursts in soft X-rays using RXTE (2.5-12 keV; ASM), and in hard X-rays with INTEGRAL (17-80 keV, IBIS/ISGRI). Using data from the JEM-X monitor onboard INTEGRAL we detected 61 Type-I X-ray bursts, and confirm that the source displayed a quasi-periodic burst recurrence time of about 2.3 hours. We improve the characterization of the fuel composition, as well as the description of the typical burst durations and fluences. We estimate the average value of $\\alpha$ to be $49\\pm\\,3$. This value together with the observed burst profiles indicate a regime of a mixed He/H runaway triggered by unstable helium ignition. In addition, we report the detection of four series of double bursts, with burst recurrence times of $\\leq\\,20$ minutes. The measured recu...

  1. Supernova sheds light on gamma-ray bursts

    CERN Multimedia

    2003-01-01

    On 29 March the HETE-II satellite detected the most violent explosion in the universe to date - an enormous burst of gamma rays. Observers across the world recorded and studied the event. It appears to prove that gamma ray bursts originate in supernovae (1 page)

  2. 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...

  3. Extensive multiband study of the X-ray rich GRB 050408. A likely off-axis event with an intense energy injection

    CERN Document Server

    De Postigo, A U; Johannesson, G; Gorosabel, J; Sokolov, V V; Castro-Tirado, A J; Balega, Y Y; Spiridonova, O I; Jelinek, M; Guziy, S; Pérez-Ramírez, D; Hjorth, J; Laursen, P; Bersier, D; Pandey, S B; Bremer, M; Monfardini, A; Huang, K Y; Urata, Y; Ip, W H; Tamagawa, T; Kinoshita, D; Mizuno, T; Arai, Y; Yamagishi, H; Soyano, T; Usui, F; Tashiro, M; Abe, K; Onda, K; Aslan, Z; Khamitov, I; Ozisik, T; Kiziloglu, U; Bikmaev, I; Sakhibullin, N A; Burenin, R; Pavlinsky, M; Sunyaev, R; Bhattacharya, D; Kamble, A P; Chandra, C H I; Trushkin, S A; Balega, Yu.Yu.

    2006-01-01

    Aims. Understand the shape and implications of the multiband light curve of GRB 050408, an X-ray rich (XRR) burst. Methods. We present a multiband optical light curve, covering the time from the onset of the gamma-ray event to several months after, when we only detect the host galaxy. Together with X-ray, millimetre and radio observations we compile what, to our knowledge, is the most complete multiband coverage of an XRR burst afterglow to date. Results. The optical and X-ray light curve is characterised by an early flattening and an intense bump peaking around 6 days after the burst onset. We explain the former by an off-axis viewed jet, in agreement with the predictions made for XRR by some models, and the latter with an energy injection equivalent in intensity to the initial shock. The analysis of the spectral flux distribution reveals an extinction compatible with a low chemical enrichment surrounding the burst. Together with the detection of an underlying starburst host galaxy we can strengthen the link...

  4. X-ray microscopy of human malaria

    Energy Technology Data Exchange (ETDEWEB)

    Magowan, C.; Brown, J.T.; Mohandas, N.; Meyer-Ilse, W. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)

    1997-04-01

    Associations between intracellular organisms and host cells are complex and particularly difficult to examine. X-ray microscopy provides transmission images of subcellular structures in intact cells at resolutions superior to available methodologies. The spatial resolution is 50-60nm with a 1 micron depth of focus, superior to anything achievable with light microscopy. Image contrast is generated by differences in photoelectric absorption by the atoms in different areas (i.e. subcellular structures) throughout the full thickness of the sample. Absorption due to carbon dominates among all the elements in the sample at 2.4 nm x-ray wavelength. Thus images show features or structures, in a way not usually seen by other types of microscopy. The authors used soft x-ray microscopy to investigate structural development of Plasmodium falciparum malaria parasites in normal and genetically abnormal erythrocytes, and in infected erythrocytes treated with compounds that have anti-malarial effects. X-ray microscopy showed newly elaborated structures in the cytosol of unstained, intact erythrocytes, redistribution of mass (carbon) in infected erythrocytes, and aberrant parasite morphology. Better understanding of the process of intracellular parasite maturation and the interactions between the parasite and its host erythrocyte can help define new approaches to the control of this deadly disease.

  5. X-ray Observations of Neutron Star Binaries Evidence for Millisecond Spins

    CERN Document Server

    Strohmayer, T E

    2001-01-01

    High amplitude X-ray brightness oscillations during thermonuclear X-ray bursts were discovered with the Rossi X-ray Timing Explorer (RXTE) in early 1996. Spectral and timing evidence strongly supports the conclusion that these oscillations are caused by rotational modulation of the burst emission and that they reveal the spin frequency of neutron stars in low mass X-ray binaries (LMXB), a long sought goal of X-ray astronomy. I briefly review the status of our knowledge of these oscillations. So far 10 neutron star systems have been observed to produce burst oscillations, interestingly, the observed frequencies cluster in a fairly narrow range from about 300 - 600 Hz, well below the break-up frequency for most modern neutron star equations of state (EOS). This has led to suggestions that their spin frequencies may be limited by the loss of angular momentum due to gravitational wave emission. Connections with gravity wave rotational instabilities will be briefly described.

  6. Adiabatic expansion, early x-ray data and the central engine in GRBs

    CERN Document Server

    Duran, R Barniol

    2008-01-01

    The Swift satellite early x-ray data shows a very steep decay in most of the Gamma-Ray Bursts light curves. This decay is either produced by the rapidly declining continuation of the central engine activity or by some left-over radiation starting right after the central engine shuts off. The latter scenario consists of the emission from an "ember" that cools via adiabatic expansion and, if the jet angle is larger than the inverse of the source Lorentz factor, the large angle emission. In this work, we calculate the temporal and spectral properties of the emission from such a cooling ember, providing a new treatment for the micro-physics of the adiabatic expansion. We compare the theoretical expectations of the adiabatic expansion (and the large angle emission) with the current observations of the early x-ray data and find that only about 20% of our sample of 107 bursts is potentially consistent with this model. This leads us to believe that, for most bursts, the central engine does not turn off completely dur...

  7. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... are easily accessible and are frequently compared to current x-ray images for diagnosis and disease management. ... of North America, Inc. (RSNA). To help ensure current and accurate information, we do not permit copying ...

  8. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... patients and physicians. Because x-ray imaging is fast and easy, it is particularly useful in emergency ... diagnosis and treatment of the individual patient's condition. Ultrasound imaging, which uses sound waves instead of ionizing ...

  9. X-Ray Assembler Data

    Data.gov (United States)

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

  10. CELESTIAL X-RAY SOURCES.

    Science.gov (United States)

    sources, (4) the physical conditions in the pulsating x-ray source in the Crab Nebula , and (5) miscellaneous related topics. A bibliography of all work performed under the contract is given. (Author)

  11. Bone X-Ray (Radiography)

    Medline Plus

    Full Text Available ... ionizing radiation to produce pictures of any bone in the body. It is commonly used to diagnose ... bone x-ray makes images of any bone in the body, including the hand, wrist, arm, elbow, ...

  12. Bone X-Ray (Radiography)

    Science.gov (United States)

    ... bony fragments following treatment of a fracture. guide orthopedic surgery, such as spine repair/fusion, joint replacement ... A portable x-ray machine is a compact apparatus that can be taken to the patient in ...

  13. 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? ... these links. About Us | Contact Us | FAQ | Privacy | Terms of Use | Links | Site Map Copyright © 2017 Radiological ...

  14. A pacemaker with P = 2.48 h modulated the generator of flares in the X-ray light curve of Sgr A* in the year 2012

    Science.gov (United States)

    Leibowitz, Elia

    2017-01-01

    In an intensive observational campaign in the nine month duration of Chandra X-ray Visionary Project that was conducted in the year 2012, 39 large X-ray flares of Sgr A* were recorded. An analysis of the times of the observed flares reveals that the 39 flares are separated in time by intervals that are grouped around integer numbers times 0.10333 days. This time interval is thus the period of a uniform grid of equally spaced points on the time axis. The grouping of the flares around tic marks of this grid is derived from the data with at least a 3.2 σ level of statistical significance. No signal of any period can be found among 22 flares recorded by Chandra in the years 2013-2014. If the 0.10333 day period is that of a nearly circular Keplerian orbit around the blackhole at the center of the Galaxy, its radius is at 7.6 Schwarzschild radii. Large flares were more likely to be triggered when the agent responsible for their outbursts was near the peri-center phase of its slightly eccentric orbit.

  15. A Pacemaker with P=2.48 hour Modulated the Generator of Flares in the X-ray Light Curve of Sgr A* in the year 2012

    CERN Document Server

    Leibowitz, Elia M

    2016-01-01

    In an intensive observational campaign in the 9 month duration of Chandra X-ray Visionary Project that was conducted in the year 2012, 39 large X-ray flares of Sgr A* were recorded. An analysis of the times of the observed flares reveals that the 39 flares are separated in time by intervals that are grouped around integer numbers times 0.10333 days. This time interval is thus the period of a uniform grid of equally spaced points on the time axis. The grouping of the flares around tic marks of this grid is derived from the data with at least a 3.2 {\\sigma} level of statistical significance. No signal of any period can be found among 22 flares recorded by Chandra in the years 2013-2014. If the 0.10333 d period is that of a nearly circular Keplerian orbit around the blackhole at the center of the Galaxy, its radius is at 7.6 Schwarzschild radii. Large flares were more likely to be triggered when the agent responsible for their outbursts was near the peri-center phase of its slightly eccentric orbit.

  16. Effects of variability of X-ray binaries on the X-ray luminosity functions of Milky Way

    Science.gov (United States)

    Islam, Nazma; Paul, Biswajit

    2016-08-01

    The X-ray luminosity functions of galaxies have become a useful tool for population studies of X-ray binaries in them. The availability of long term light-curves of X-ray binaries with the All Sky X-ray Monitors opens up the possibility of constructing X-ray luminosity functions, by also including the intensity variation effects of the galactic X-ray binaries. We have constructed multiple realizations of the X-ray luminosity functions (XLFs) of Milky Way, using the long term light-curves of sources obtained in the 2-10 keV energy band with the RXTE-ASM. The observed spread seen in the value of slope of both HMXB and LMXB XLFs are due to inclusion of variable luminosities of X-ray binaries in construction of these XLFs as well as finite sample effects. XLFs constructed for galactic HMXBs in the luminosity range 1036-1039 erg/sec is described by a power-law model with a mean power-law index of -0.48 and a spread due to variability of HMXBs as 0.19. XLFs constructed for galactic LMXBs in the luminosity range 1036-1039 erg/sec has a shape of cut-off power-law with mean power-law index of -0.31 and a spread due to variability of LMXBs as 0.07.

  17. Effects of variability of X-ray binaries on the X-ray luminosity functions of Milky Way

    CERN Document Server

    Islam, Nazma

    2016-01-01

    The X-ray luminosity functions of galaxies have become a useful tool for population studies of X-ray binaries in them. The availability of long term light-curves of X-ray binaries with the All Sky X-ray Monitors opens up the possibility of constructing X-ray luminosity functions, by also including the intensity variation effects of the galactic X-ray binaries. We have constructed multiple realizations of the X-ray luminosity functions (XLFs) of Milky Way, using the long term light-curves of sources obtained in the 2-10 keV energy band with the RXTE-ASM. The observed spread seen in the value of slope of both HMXB and LMXB XLFs are due to inclusion of variable luminosities of X-ray binaries in construction of these XLFs as well as finite sample effects. XLFs constructed for galactic HMXBs in the luminosity range 10^{36} - 10^{39} erg/sec is described by a power-law model with a mean power-law index of -0.48 and a spread due to variability of HMXBs as 0.19. XLFs constructed for galactic LMXBs in the luminosity r...

  18. Applications of Indirect Imaging techniques in X-ray binaries

    CERN Document Server

    Harlaftis, E T

    2000-01-01

    A review is given on aspects of indirect imaging techniques in X-ray binaries which are used as diagnostics tools for probing the X-ray dominated accretion disc physics. These techniques utilize observed properties such as the emission line profile variability, the time delays between simultaneous optical/X-ray light curves curves, the light curves of eclipsing systems and the pulsed emission from the compact object in order to reconstruct the accretion disc's line emissivity (Doppler tomography), the irradiated disc and heated secondary (echo mapping), the outer disc structure (modified eclipse mapping) and the accreting regions onto the compact object, respectively.

  19. 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.

  20. X-ray fluorescence holography

    CERN Document Server

    Hayashi, K; Takahashi, Y

    2003-01-01

    X-ray fluorescence holography (XFH) is a new structural analysis method of determining a 3D atomic arrangement around fluorescing atoms. We developed an XFH apparatus using advanced X-ray techniques and succeeded in obtaining high-quality hologram data. Furthermore, we introduced applications to the structural analysis of a thin film and the environment around dopants and, discussed the quantitative analysis of local lattice distortion. (author)